Science topics: Chemistry
Science topic

Chemistry - Science topic

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds.
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I am looking for a easy-to-use software, which can generate analogues based on one structure. I do not need to teach it what kind of activity compound has, I just need to have the structures generated so I can run it though QSAR (which was already set based on 80 compounds).
Does anyone have experience with this?
I would be grateful for any recommendations.
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Gentleman, thank you very much for your answers. They helped me a lot and I already moved foreward with my research.
I really appreciate for the help.
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Chemical Informations
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Melting point of thiophene is −38 °C, it is liquid at room temperature. It smells like benzene, but the fumes are best avoided due to toxicity.
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I prepare a chitosan solution in acetic acid (0.5 M). Some of the small threads are remained in the solution. In literature it is reported that solution is filtered before using. I want to know which filter is suitable for the filtration of chitosan solution?
Thanks
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You can use-Whatman 1 cellulose fibre filter paper - pyramid folded - diameter 125 mm- grade 1
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Hi
I am using copper nitrate salt for my experiments. After 2 years, the salt crystals turned into liquid.
I am using copper nitrate trihydrate salt. Kindly let me know how can i store copper nitrate salt for long term?
Thank you
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Hello Noor Ul Ain ,
Your copper nitrate trihydrate is a deliquescent salt, which means that it will absorb water from the atmosphere and eventually liquify. The only way to slow down this process is to store the bottle containing the salt in a sealed descicator backfilled with dry nitrogen gas. Every time you take out and open the bottle to use some of the salt, you should backfill the bottle with dry nitrigen gas before you screw the bottle lid back on and place the sealed bottle back in the descicator, which you refill with dry nitrogen gas.
Regards,
Tom Cuff
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I have performed drug repositioning to find antifungal activity. I need to explain the possible causes of why some drugs had antifungal activity and others did not. any suggestions?
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Can you be more specific? What is "repositioning" and to what "drugs" do you refer?
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There is some guide or ranking of the better congress of soils and chemical science?
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Since you're located in a pacific country, maybe check out if the PacifiChem has the right segment for you.
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Is there any good chemistry book about heavy metal precipitation/ extraction via chemical / chelate method?
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i don't know
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Hello, I am fairly new to gromacs and molecular dynamics. I want to simulate thiols for starters for some applications and I want to generate the topology file for thiol. I found the PDB and ITP files for sulfanyl from ATB -
and I tried to use ‘pdb2gmx’. I have read up on the documentation but I can’t get it to work. I am stuck on how to modify a forcefield or how to simply create a new one for the molecule. Any help on how to generate the topology and gro files would be appreciated. Thanks
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Hi, you already got the topology file (itp), so you don't need topology.
In your case, just create the protein topology using pdb2gmx and then combine it later. YOu should follow this tutorial:
Just consider the thiol group as a ligand. If you have downloaded it from the ATB, then, I hope the structure and charges are already optimized.
Good luck.
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In the Column treatment of aqueous solution of Chromium Removal by Adsorption
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Treating bark with acid (HCl) first and then with base (NaOH) second is a common method for isolating plant compounds for analysis or extraction, such as tannins, lignin, and cellulose. This method is known as acid-base treatment or A/B extraction.
The reason for this order of treatment is that acid treatment hydrolyzes and breaks down the plant cell walls, making the cell contents more accessible for extraction. Acid treatment can also help to remove impurities, such as pigments and waxes, from the sample.
After acid treatment, the sample is then neutralized with a base, typically sodium hydroxide (NaOH), to restore the pH to a neutral or slightly alkaline state. The neutralization step is important to prevent the acid from interfering with subsequent analytical techniques or reactions.
The use of acid and base treatments in this order allows for selective extraction of different plant compounds based on their solubility and chemical properties. For example, tannins are more soluble in acidic solutions, while lignin and cellulose are more soluble in basic solutions.
Treating the bark with base first would result in a saponification reaction, where the ester linkages in the plant compounds would be hydrolyzed by the base, resulting in a loss of their original structure and properties. Therefore, treating the bark with acid first and then with base is the preferred order for A/B extraction of plant compounds from bark.
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What is the effect of diluent in nitrosamine recovery?
Candesartan Cilexitil is insoluble in water but we are getting good recovery in water and not in methanol for certain nitrosamines (NDIPA, NDPA). Can anyone suggest chemistry behind that?
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The effect of diluent on nitrosamine recovery can vary depending on the specific diluent used and the chemical properties of the nitrosamines and drug substance. In some cases, the presence of certain solvents or diluents can enhance the recovery of nitrosamines, while in other cases, they can have the opposite effect and decrease the recovery.
Regarding your specific question about candesartan cilexetil, the reason why you are getting good recovery of certain nitrosamines in water but not in methanol could be due to differences in the solubility and chemical properties of the drug substance and nitrosamines in the two solvents.
Candesartan cilexetil is generally considered to be insoluble in water, but it is possible that certain impurities or components in the drug substance could be soluble in water and thus affect the recovery of nitrosamines. On the other hand, methanol is a more polar solvent that may interact differently with the drug substance and nitrosamines.
In addition, the specific nitrosamines in question, NDIPA and NDPA, have different chemical structures and properties, which could affect their solubility and recovery in different solvents. Without more detailed information about the specific experimental conditions and methods being used, it is difficult to provide a definitive answer.
However, in general, factors such as solvent polarity, pH, and temperature can all affect the solubility and recovery of nitrosamines and other impurities during the extraction process. Careful selection of appropriate solvents and optimization of extraction conditions are important to ensure accurate and reliable measurements of nitrosamines and other impurities in drug substances.
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Although formed over thousands of years, carbonate ramps forming where ocean sediments accumulate multicellular algae may be affected by ocean chemistry in such a way as to have a unique morphology.
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Hi Tristan, in my experience with carbonate ramps the role of algae would be secondary to other factors that would, in fact, control the type and distribution of algae. These factors would include the slope of the surface that the ramp grows on and climatic conditions. One good outcrop example comes to mind that you might want to check out: The Permian San Andres (note: not a misspelling of San Andreas) carbonates occur as a series of ramps that gradually give way upward into a rimmed shelf capped by the famous Capitan Reef of Guadalupe Mountains National Park. The literature is voluminous so you could research the role of algae in the ramps vs. rimmed shelves and maybe see something no one has thought of before. Cheers!
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How are deep ocean currents affected by these types of occurences? How is the ocean chemistry equilibrating alobg these geographies?
Do current terrestrial models incorporate data and equations to reflect these types of changes to a static estimation of the biosphere?
Do climate model researchers incorporate models of ecological regions underwater?
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Hydrothermal vents and lava flows can affect upwelling and ocean currents in a number of ways.
Hydrothermal vents are underwater geysers that release hot, mineral-rich water into the ocean. The heat and chemicals released by these vents can create a unique ecosystem that supports a variety of marine life. The heat can also contribute to upwelling, which is the process by which deep, nutrient-rich water rises to the surface. This can have a significant impact on ocean currents, as upwelling can alter the temperature and salinity of the water, affecting the direction and strength of currents.
Lava flows, on the other hand, can create new land masses or alter existing ones, which can also have an impact on ocean currents. For example, the formation of new islands or the alteration of coastlines can affect the direction and strength of currents, as well as the distribution of nutrients and other materials in the water.
The ocean chemistry in these areas is also affected by the release of heat and minerals from hydrothermal vents and the alteration of land masses from lava flows. These changes can create unique chemical environments that support certain types of marine life and affect the overall chemical balance of the ocean in those regions.
Current terrestrial models do incorporate data and equations to reflect the impact of hydrothermal vents and lava flows on the biosphere. However, the extent to which these models incorporate data on deep ocean currents and the impact of underwater ecological regions on climate models may vary.
Climate model researchers do incorporate models of ecological regions underwater, as these regions can play a significant role in the overall climate system. However, there is still much to be learned about the complex interactions between deep ocean currents, underwater ecosystems, and climate change. Ongoing research and data collection are necessary to improve our understanding of these processes and incorporate them into climate models.
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Advantages and disadvantages of teaching chemistry through elective courses. Increasing students' interest in chemistry through elective courses. Organization of elective courses in chemistry. Scientific-pedagogical basis of creating the elective course "Polymer materials". Scientific-pedagogical basis of creating the elective course "Ion exchange materials".
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Hai KS
The effectiveness of teaching chemistry through elective courses depends on many factors, such as the quality and relevance of the course material and the qualifications and enthusiasm of the instructor. Some benefits of teaching through electives include engaging students in the subject, developing students' critical thinking skills, and encouraging independent learning. Disadvantages include unequal distribution of resources and an inability to keep up with the latest developments in the field. To ensure the success of elective courses in chemistry, it is necessary to have a clear scientific-pedagogical basis for their development. This basis should include a thorough introduction to the topics covered in the course and a discussion of their associated practical applications. It is also important to consider course goals and expectations, as well as students' prior knowledge and existing skills. Finally, it is important to create engaging and interactive activities that capture students' interest and motivate them to learn.
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Como es posible solubilizar una membrana de colágeno sin perder la propiedad química del colágeno?
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Extracción de colágeno sin perder las propiedades químicas. Cada método tiene ventajas y desventajas. Piensa que necesitas usar al menos dos métodos. Incluyo adjunto un artículo que compara una "solubilización" ácida y enzimática. Se incluyen varios métodos de caracterización.
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I am a PhD student in Chemistry.
  • For drawing chemical structures, I have tried using some random softwares like Kingdraw, etc, but the GUI does not seem appealing and not easy to use overall.
  • I have used sometimes the well-known softwares such as ChemDraw and ChemSketch in someone else's device, but I am unable to install them on my device in a straight-forward manner.
  • I am looking for the list of the best drawing tools (softwares/freewares) which are easily accessible and will faciliate to draw better quality chemical structures, good enough for publications in peer-reviewed journals.
  • Your help, suggestions, feedbacks, links are highly valued and appreciated from my end.
With Many thanks,
Janaki Devi Somasundaram
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Dear Janaki Devi Somasundaram
If you need use the software for organic chemical structures i advise https://biomodel.uah.es/en/DIY/JSME/draw.es.htm from Alcalá University, many times I used for draw and was really usefull, is free and you can use online don't need download.
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Good morning everyone. They know some pages about virtual chemistry laboratories, with special attention to high school education.
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I am a researcher in chemistry, in which I have to use Pd as a catalyst. In every reaction, I have to change the millimoles of the reactants. But I can't understand how to calculate the millimoles of catalyst that should be used in a reaction according to millimoles of reactants or according to millimoles of the reactant on which the catalyst is attached during the reaction mechanism.
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One is using 5 or 10 % Pd on carbon to conduct hydrogenation of a number of functional groups in substances, then other factors are the solvent; the hydrogen pressure one provides to the Parr apparatus (and conduct the shaking in a constant way). One can calculate the amount but Pd/C is a catalyst which means that after reaction it will be present in almost quantitative way. I would advise to check the literature and take into account the amount of Pd/C which is reasonable. At the limit if you would use equal millimoles Pd/C and substrate, your reaction might not proceed quicker. In making 100 substances during my Ph.D I have always used say 50-100 mg for 20-25 g of substrate (I NEVER calculated millimoles). One reaction I recall is the conversion of 4-nitro-anthranilic acid to 4-amino-anthranilic acid with Pd/C in ethanol overnight at 3 bar hydrogen overnight.
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Hi there,
I know that some UK universities can provide PhD by publications in medical sciences, but I cannot have idea about which universities worldwide that provide PhD by publications in chemistry.
Please let me know if there is any information
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What you are searching for is a so-called "cumulative doctoral thesis" [or in German "kumulative Promotion"]. There are some universities which offer it as an option, although I am not aware of any database on the issue.
If you have it as an option, it's probably a nice thing, but publications in general aren't plannable before your PhD work assuming you don't set a low bar for your research, so you must always stay ready to write a monography thesis.
In any case, I wouldn't recommend making that the top priority for choosing which group you join. The major criteria should be (a) that the topic is interesting enough for you to spend several yours of your life on it and (b) that the group you join is decently managed.
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Please spread the word: Folding at Home (https://foldingathome.org/) is an extremely powerful supercomputer composed of thousands of home computers around the world. It tries to simulate protein folding to Fight diseases. We can increase its power even further by simply running its small program on our computers and donating the spare (already unused and wasted) capacity of our computers to their supercomputation.
After all, a great part of our work (which is surfing the web, writing texts and stuff, communicating, etc.) never needs more than a tiny percent of the huge capacity of our modern CPUs and GPUs. So it would be very helpful if we could donate the rest of their capacity [that is currently going to waste] to such "distributed supercomputer" projects and help find cures for diseases.
The program runs at a very low priority in the background and uses some of the capacity of our computers. By default, it is set to use the least amount of EXCESS (already wasted) computational power. It is very easy to use. But if someone is interested in tweaking it, it can be configured too via both simple and advanced modes. For example, the program can be set to run only when the computer is idle (as the default mode) or even while working. It can be configured to work intensively or very mildly (as the default mode). The CPU or GPU can each be disabled or set to work only when the operating system is idle, independent of the other.
Please spread the word; for example, start by sharing this very post with your contacts.
Also give them feedback and suggestions to improve their software. Or directly contribute to their project.
Folding at Home's Forum: https://foldingforum.org/index.php
Folding at Home's GitHub: https://github.com/FoldingAtHome
Additionally, see other distributed supercomputers used for fighting disease:
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Vahid Rakhshan I will definitely spread the word about this amazing initiative. It's great to know that we can contribute to such a noble cause by simply utilizing our excess computer power. Thank you for bringing this opportunity to my attention. Let's join hands in making a difference in the fight against diseases.
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I am currently planning some lab work that requires me to dissolve tris(2,20 -bipyridyl) ruthenium(III) chloride hexahydrate dye in a solvent in order develop a calibration curve relating phosphorescence lifetime and quencher concentration (In this case O2 is the quencher). I'm currently trying to figure out what solvent is best for the application. My background is in biomedical engineering and not chemistry, so my reasonably basic knowledge chemistry is not much help!
I had considered water as a solvent but figured the presence of dissolved O2 would potentially lead to inaccuracies in the oxygen concentration for the calibration curve. If I used a Schlenk line of nitrogen to remove the dissolved O2, would degassed water be a viable option for the solvent?
In regards to mixing O2 with the solvent and maintaining a desired O2 concentration within the solution, I have read articles where a mass flow controller was used to achieve desired O2 concentration, can anyone confirm this method? Any suggestions / guidance is greatly appreciated!
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I would not recommend to add [Ru(II)(bpy)3]2+ to your sample. Illumination of your sample with 454 nm light will result in an extremely complex photochemically initiated processes in your sample. In commercially available O2-sensors the sample is separated from [Ru(II)(bpy)3]2+ solution by a membrane. Such a sensor is a pretty complex device but not very expensive (several hundred US$).
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I’d like to determine the monomer conversion through gel fraction. The experimental process I read in some papers was described in a simple way, omitting some details. I wonder how to filter the soluble substances and the insoluble one? In what way?
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Measuring the gel fraction is important in determining the monomer conversion in polymerization processes. The gel fraction is defined as the fraction of the polymerized material that has formed a three-dimensional network, which is insoluble in the solvent used for polymerization.
  1. Filter the reaction mixture: After the complete polymerization reaction, the mixture is filtered to separate the insoluble gel from the soluble monomers and other reaction by-products. This can be done using filter paper or a filtering centrifuge. To measure the gel fraction, the following steps can be taken:
  2. Wash the gel: The filtered gel is then washed with the solvent used for polymerization to remove any residual monomers and other soluble substances. This can be done by repeatedly resuspending the gel in the solvent and filtering it.
  3. Dry the gel: After washing, the gel is dried in an oven or vacuum drier to remove any remaining solvent.
  4. Weigh the gel: Finally, the dried gel is weighed to determine the gel fraction. The gel fraction is calculated as the gel's weight divided by the reaction mixture's total weight.
It is important to note that the gel fraction can be affected by various factors, such as the type and amount of initiator used, the temperature and pressure conditions, and the molecular weight of the polymer. Therefore, it is important to carefully control these variables and standardize the measurement procedure to ensure accurate and reproducible results.
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I want to deacetylate the chitosan in sodium hydroxide (50 % w/w) solution. Does that mean 50 g NaOH in 50 mL of distilled water? What should be the appropriate time and temperature for the complete process? There are different temperatures and times are reported in literature.
Thank you for your help!
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The reaction time and the temprature depends on the level of deacetylation that you would like to achieve. If you let your mixture react longer then the level of deacetylation will be higher.
You might need to experiment a bit till you get a product that has the desired characteristics. Or if you have a procedure for a product with the desired characteristics in the literature then you can simply follow that and get some good results.
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I am trying to optimise an organic molecule using Avogadro software, and when I draw the molecule according to the correct sterochemistry (some bonds coming towards the screen and some going away from the screen) whenever I optimise the molecule using one of the forcefields the stereo chemistry starts to change and therefore some bonds face the wrong plane, is there a way to optimise the molecule without changing its stereochemistry in avogadro software?
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Hi Wares,
This is very odd, and I have yet to experience such a problem. I guess that we are talking about point chirality where a carbon atom is a stereogenic center, and not axial or planar chirality? Could you share the molecule that you're talking about? Maybe that could give some insight into the issue.
Also, I would suggest you not to use molecular mechanics for the optimization (Avogadro offers only MM), but rather semiempirical methods or, even better, some DFT calculations. For semiempirical calculations, you could try ArgusLab software, it is free and fairly easy to use. It is getting a bit dated by now, but you'll get somewhat reasonable structures (for sure better than MM optimization). Also, MOPAC is a good software if you have some experience using it, but otherwise, I'd suggest using ArgusLab. However, DFT is the way to go if you need good structures. There are some free software packages (such as NWChem or GAMESS), and you could use Avogadro as a graphical interface.
Hope this helps.
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I made several reactions with 3,5-Dinitrobenzoyl chloride. When I looked at similar reactions for this substance, no heat was ever given in the reaction (even though heat increases the yield).
The interesting thing is that this substance turns black as soon as the heat is given to the reaction environment. Due to the fact that, theoretically, the polymerization of this material is impossible. Do you know the reason why they do not give heat to this material?
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If we have a crystal with a coordination number of five, triangular bipyramidal(TBP) and square pyramid(SP) are expected. An intermediate state may also be obtained due to Barry's pseudo-rotation. But if the crystal data did not match any of the structures and the shape deviation was excessive, what structure should be reported? I also used the following formula, but it didn't work. What structure should I report?
•Pictures from reference, Chemistry of coordination compounds by M.M.Pouramini, N.Safari, K.Darzinezhad
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Applying the Addison parameter τ5 (a geometric parameter permitting the identification of the geometry around the central atom whether it is trigonal bipyramidal or square pyramidal) to describe the coordination polyhedron.
τ5 = (β-α)/60
where β and α are the two largest ligand–metal–ligand angles of the coordination sphere (τ = 0 for an ideal square pyramidal geometry and τ = 1 for an ideal trigonal bipyramidal geometry)
Refrences :
Hchicha, K., Korb, M., Badraoui, R., & Naïli, H. (2021). A novel sulfate-bridged binuclear copper (II) complex: Structure, optical, ADMET and in vivo approach in a murine model of bone metastasis. New Journal of Chemistry, 45(31), 13775-13784.
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Using DFT, I have a graphene system with Nitrogen doping. It is well known that the nitrogen covalent bonds with 3 sp2 hybridized carbon atoms. When placing this system on top of an Silica which contains Si surface atoms having sp3 hybridization (Si has one free electron), the Nitrogen creates a covalent bond with Si.
My question is, what happens to the lone pairs in nitrogen ? How can it bind with the electron in Si even though it has lone pairs.
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No, nitrogen in graphene cannot form covalent bonds through one of its lone pairs. Nitrogen atoms in graphene are typically incorporated as nitrogen doping and form pyridinic nitrogen, which only has one N-C bond, rather than covalent bonds.
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The m
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Your cyclic peptide also includes a thiazole.
Check
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in the matter of measuring the content of a certain component in botanical chemistry
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The dry weight of the plant is determined based on the certain amounts of live/wet plant biomass and is variable (the physical, chemical and biomechanical processes are carried out in its content). The dry extract of the plant will undergo a physical phase change after the initial extraction based on a series of special post-processing in accordance with the relevant protocols.
Regards
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How many grams of K2Cr2O7 to dissolve it in 1 liter Distilled water to obtain 50 ppm of Chromium? to become aqueous solution, Is there a specific equation to apply? Thanks
Ali
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Errami Ahmed answer is correct. 52 is the atomic weight of Cr and 294.18 is the molecular weigh of potassium dichromate. 2 is the stechiometric conversion factor.
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is it possible to calculate photoelectron Circular dichroism (PECD) using quantum chemistry?
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Photoelectron circular dichroism (PECD) is a phenomenon that occurs when a molecule is irradiated with circularly polarized light, resulting in a difference in the yield of photoelectrons emitted from the molecule depending on the handedness of the circular polarization. PECD can be used to study the chiral properties of molecules, and is sensitive to the electronic and geometric structure of the molecule.
To calculate PECD using quantum chemistry, one can use a multi-reference configuration interaction (MRCI) approach, which is a method for treating electron correlation in molecules. MRCI calculations can be used to calculate the transition dipole moments for different electronic states, which are needed to calculate the PECD signal.
Another approach is time-dependent density functional theory (TD-DFT) which is a first-principle method to calculate PECD signal. TD-DFT can be used to calculate the transition dipole moments, and the PECD signal can be calculated by comparing the transition dipole moments for different electronic states.
It is important to note that the PECD signal is usually very small and difficult to measure experimentally and so it is important to use high level of theory and a good basis set to obtain accurate results.
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Hello,
I need to take the sodium nucleotide salts I have available in my lab and modify them to instead contain some more exotic counterions. Can I do this by binding my nucleotides to a strong anion exchange resin, washing, and eluting with a salt of my preferred counter ion?
Thanks very much!
Nikhil
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You can do either of two things:
1. First, convert a Dowex cation exchanging resin, H+ form, to the desired ionic form by washing with 0.5-1M solution of a salt containing the desired cation followed by the extensive washing of the resin with water. Next, pass, at a slow flow rate, an aqueous solution of your nucleotide through a column containing min. 10-fold excess of the resin prepared as above and wash the column with several volumes of water to complete the elution of the nucleotide. Freeze-drying will give you your nucleotide in the desired ionic form.
2. If your nucleotide is retained on a C18 reverse phase column, you can dissolve the nucleotide in a solution containing the desired cation and apply the solution to the column. Next, wash the column with 3 volumes 0.1 M aqueous solution of the salt containing the desired cation. Next, wash the column with water, min 1 column volume. Finally, elute the nucleotide with 10-15% aq acetonitrile and evaporate the eluate to dryness. It would be advantageous to monitor the UV absorbance of all eluates by an on-line detector and collect only the UV-absorbing fractions. Not all nucleotides are retained by C18 reverse phase, particularly in the step of washing with water. If you decide to use this method make sure to check all eluted fractions.
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I want to prepare 2% solution of chitosan using 0.5 M acetic acid but need to adjust pH to 4. How can I do that? I added NaOH to the chitosan solution, precipitates were formed in chitosan solution.
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In case you want to consider an acetic acid / sodium acetate buffer solution:
The pKa of acetic acid is 4.75, from what we can only expect fair pH buffering effect between approx. 3.75 to 5.75. The pH of acetic acid / sodium acetate buffer solutions can be simply calculated based on the Henderson-Hasselbalch equation, after the molar concentrations of acetic acid (Ca) and sodium acetate salt (Cs) at the buffer solution: pH = pKa + log10(Cs/Ca); what can be generally expected to hold for Ca > 100Ka. A possible derivation for this equation, along with a justification for the stated minimum concentration limit for its validity, can be found elsewhere at this forum: https://www.researchgate.net/post/pH_calculation_of_a_mixture_of_formic_acid_NaOH_and_water
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Some Oxford Nanopore kits have Primers with 5 ' modification that provide ligation to adapters without the need for ligases (ligase-free method), as in 16S barcoding kits. Does anyone know what modification this is or the chemistry involved in the process? I'm very grateful if anyone can help me with this information. Thanks.
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I'm also concerned about this because the Nanopore's Barcode recognition often goes wrong
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If I want to synthesize the product shown in the image, would it be faster to use option A as the starting material or option B. My goal is to synthesize the product in the space of 4-5 hours, which is the best option to use? also what reagents should be used for the synthesis? i was thinking of mixing the starting material with dry methanol and then adding TMSCl while the solution is in an ice bath then removing the mixture from the ice bath and stirring till the reaction is complete. the issue I have is that this reaction usually would take much longer to complete. what is the best way to approach this problem?
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Hi, the starting material doesn't matter. I would use the unprotected amino acid (its way more cheaper), add dry methanol and at least 5 eq of TMSCl. Starting with an ice bath and after 30 min stirring raise to 40 °C for 2-3 h. Check the reaction progess via TLC. Good luck.
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Some researchers say the type of surface electrical charges effects on pH value of the reaction medium and thus the adsorption and removal process , when pH value increases, the overall surface electrical charge on the adsorbents become negative and adsorption process decreases, while if pH value decreases, surface electrical charge become positive and adsorption process increases
Malkoc, E.;Nuhoglu, Y. and Abali,Y. (2006). “Cr (VI) Adsorption by Waste Acorn of Quercus ithaburensis in Fixed Beds: Prediction of Breakthrough Curves,” Chemical Engineering Journal, 119(1): pp. 61-68.
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At lower pH, the adsorption backpedal by H+ ion factor or proton factor and at higher pH, adsorption hampered because of yhe metallic ions start to precipitate as metallic hydroxide or metallic oxide. So it is looking good the pH value near between 4-6, and you should have to study for optimum pH for the removal of particular metal like Cr.
On contrast, time mainly find out the breakthrough time for column study is not so easy like batch study. Here you need to conduct a lot of trial and also need to modeling of Thomas model, Adam-Bohart model, Yoon-Nelson model for the much more accurate BTC curve.
Thank you.
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I admitted as an undergraduate to multiple universities in Arizona and Colorado! I have been actively looking for admission to the university to continuously prepare me as an investigator/innovation scientist in mineral exploration by building my foundational knowledge in metallurgy, chemistry, control systems engineering, geochemistry, geophysics, etc. These might be included in my coursework. My focus may be on "control system engineering" compared to "geoscience," as I want to spend my effort investigating sensor innovation using metallurgy, geophysics, chemistry, etc. for mineral exploration. Precisely, investigative research will be on creating "detection technology for purposing of Mining exploration and extraction" So, I'm confused with two queries: 1. Which university would be the best option based on my research interests? 2. Which major and region for internship/ real time research job corresponds to what I'm actually looking for?
Hope you already understand I’ve applied many universities with getting rejection that didn’t also find exact research team yet I’m looking. Thank you so much.
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Dear Saifur Rahman Khan and Al,
lI wish you Happy New Year: success in your spiritual achievement, good health and prosperity for it!
I found the next on the facbook (https://www.facebook.com/USGSVolcanoes):
'A volcanologist is a person who studies volcanoes, but there are many different specialties within the field of volcanology. Which interests you and what steps should you take to achieve your goal? Find out more in #VolcanoWatch.
Earthquakes are one primary tool used to study volcanoes. A volcano seismologist studies the earthquakes that are generated as magma moves through Earth’s crust.
A volcano geodesist studies the deformation, or change in shape, of a volcano caused by the movement of magma and gases beneath the surface. Many features of volcanoes can be studied from space, as well, using satellite sensors. Tools like these provide clues about the state of the volcano.
Geologists and geochemists study the composition of lavas and gases to understand the source and style of the eruption. Measuring gas emissions is especially important, as the vog (volcanic air pollution) caused by toxic volcanic gases can contribute to breathing problems, acid rain, and agricultural problems downwind, especially during long-lived eruptions.
If you are interested in becoming a volcanologist, you’ll need to work toward a bachelor’s degree, preferably in a STEM field (Science, Technology, Engineering, and Math). Volcanologists frequently pursue degrees in geology, chemistry, physics, and/or mathematics, but that is not always the case. Oceanography, computer science, engineering, environmental science are all potential pathways, and the list goes on. Explore different fields to find what interests you most.
After achieving a bachelor’s degree, consider options for advanced degrees like a Masters or Doctorate. Many advanced degree programs in the sciences are funded, meaning tuition may be waived, and you might get a stipend for doing the work. Basically, you get paid instead of having to pay for school, and you gain valuable work experience at the same time.
You might consider working for the USGS or other agencies and companies. You have seen many photos of HVO scientists working during the eruptions of Mauna Loa and Kīlauea. The National Park Service also offers a variety of positions for people with either bachelor’s or advanced degrees, such as park geologists, archaeologists, botanists, guides, interpretive rangers, and law enforcement rangers. Science writing and journalism are also excellent ways to explore the excitement of volcanology, natural disasters, and cutting-edge science, while encouraging those passions in others. Similarly, eco- and geo-tourism are great ways to get close to the action and work outdoors, while also meeting, educating, and inspiring people from all over the world. Careers in emergency management will have you helping people stay informed during crises.
Check out usajobs.gov for positions within the federal government. There is even a special section for students and recent grads.
Volcano Activity Updates
#MaunaLoa is not erupting. Webcam imagery shows weak, residual incandescence intermittently in the inactive Northeast Rift Zone fissure 3 lava flow at night. Seismicity remains low and ground deformation rates have decreased. Sulfur dioxide (SO2) emission rates are at background levels. For Mauna Loa monitoring data, see: https://www.usgs.gov/volcanoes/mauna-loa/monitoring-data.
#Kilauea is not erupting. Lava supply to the Halemaʻumaʻu lava lake in Hawai‘i Volcanoes National Park ceased on December 9. Sulfur dioxide emission rates have decreased to near pre-eruption background levels and were last measured at approximately 200 tonnes per day (t/d) on December 14. Seismicity is elevated but stable, with few earthquakes. Over the past week, summit tiltmeters recorded several deflation-inflation (DI) events. For Kīlauea monitoring data, see https://www.usgs.gov/.../past-week-monitoring-data-kilauea.
There were three earthquakes with 3 or more felt reports in the Hawaiian Islands during the past week: a M3.3 earthquake 14 km (8 mi) S of Fern Forest at 7 km (4 mi) depth on Dec. 27 at 4:33 a.m. HST, a M3.4 earthquake 7 km (4 mi) WSW of Volcano at 2 km (1 mi) depth on Dec. 24 at 8:31 p.m. HST, and a M2.5 earthquake 1 km (0 mi) S of Mountain View at 11 km (7 mi) depth on Dec. 24 at 9:57 a.m. HST.
In the photo, an HVO technician adjusts a volcanic gas analysis instrument that was specifically designed for this Unoccupied Aircraft System (UAS) unit, which carries three one-liter analysis bags. The instrument transmits gas concentration information in real-time during the flight at Kīlauea summit. USGS has special use permits from the National Park Service to conduct official UAS missions as part of HVO's mission to monitor active volcanoes in Hawaii, assess their hazards, issue warnings, and advance scientific understanding to reduce impacts of volcanic eruptions. Launching, landing, or operating an unoccupied aircraft from or on lands and waters administered by the National Park Service within the boundaries of Hawai‘i Volcanoes National Park is prohibited under 36 CFR § 1.5 - Closures and public use limits.
USGS image taken January 14, 2022 by M. Warren.
#USGS #HVO #HawaiianVolcanoObservatory'
Maybe it can help you!
Regards,
Laszlo
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Hello All! I am working on a project that uses stable isotope analysis (C and N) to look at the diets of California reef fishes. I am going to be collecting Liver and White muscle tissue. It was suggested to me to use 20ml borosilicate glass scintillation vials (urea caps with polyurethane lined caps/not foil lined) for my tissues. I will be freezing the tissue samples in the vials and drying them in a 65C drying oven in them as well. The issue I am running into is that every brand of vials are back ordered for about 4 months no matter where I look.
So I wanted to see if 1. Anyone in the southern California/greater LA Area had vials I could buy off of them to use. Or 2. If anyone knew of a substitute I could use. It has been suggested that I could hand make aluminum foil packets, pre combust them, and store/dry the tissue in those. However, I would prefer the glass vials for both, organization/storage sake as well as I will eventual be grinding the powder into a powder and vials would be less likely to fail with the powder.
Thank you in advance for any advice!
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It is not uncommon for certain lab supplies to be in high demand or backordered due to various reasons such as an increase in demand for certain types of research or supply chain disruptions. In such cases, it may be helpful to try reaching out to the manufacturer or distributor directly to see if they can provide any information on when the vials will be back in stock. Additionally, you can try looking for alternative suppliers or checking with local scientific supply companies to see if they have any borosilicate glass vials in stock.
Alternatively, you could consider using other types of containers for storing and drying your tissue samples. For example, you could use pre-combusted aluminum foil packets as you mentioned, or you could try using pre-combusted tin capsules or pre-combusted glass vials. It is important to ensure that the containers you use are properly combusted and clean to avoid contamination of your samples.
It is also worth noting that the type of container you use may depend on the specific requirements of your stable isotope analysis method. It is always a good idea to consult with your laboratory or the manufacturer of the stable isotope analysis equipment to ensure that the container you choose is suitable for your specific application.
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Greeting,
When I tried to remotely accessed the scopus database by login into my institution id, it kept bring me back to the scopus preview. I tried cleaning the cache, reinstall the browser, using other internet and etc. But, none of it is working. As you can see in the image. It kept appeared in scopus preview.
Please help..
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To reach the Scopus document search module, you should use academic IPs. If your institute has been listed in the Scopus database, you have permission to search documents in Scopus. It is not free of charge, and your university should pay its share to Scopus to provide this service for its academic researchers.
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Hey,
I'm looking for an article that explains that inductive and resonative effects are components of pi bonds. That is what my PI claims.
Thanks.
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We have a substance. We study it using physical methods and determine that its molecules have a dipole moment , they are polarized under the action of an external electromagnetic field ... We determine the structure of the molecule. We compare with other molecules and come to the conclusion that in some molecules the electron density shifts under the action of a magnetic field along a chain of sigma bonds (inductive effect). For other molecules, the electron density shifts along the chain of pi bonds (resonant effect). Bonds between atoms in molecules are primary, while inductive and resonant effects are secondary.
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Hi everyone!
I project to measure levels of total phenolic compounds in peppers following the method of the Folin-Ciocalteu's reagent, and I am going to calculate them by reading absorbance using gallic acid as a standard.
Nevertheless, I am confused about what wavelenght should be setted: while some authors read absorbance at 765 nm (Dogan et al., 2018; Kupina et al., 2018); others read it at 760 nm (Ghasemnezhad et al., 2011); 750 nm (Toledo-Martín et al., 2015; Lwin et al., 2022) or even 725 nm (Vega-Gálvez et al., 2009).
I would be grateful if someone could give me some light about this.
Thanks to everyone in advance.
Pablo
Literature cited:
Dogan, A.; et al. (2016). Comparison of pesticide-free and conventional production systems on postharvest quality and nutritional parameters of peppers in different storage conditions. Scientia Horticulturae 207: 104-116.
Ghasemnezhad, M.; et al. (2011). Variation in phenolic compounds, ascorbic acid and antioxidant activity of five coloured bell pepper (Capsicum annum) fruits at two different harvest times. Journal of Functional Foods 3: 44-49.
Kupina, S.; et al. (2018). Determination of total phenolic content using the Foling-C assay: Single-Laboratory validation, First Action 2017.13. Journal of AOAC International 101 (5): 1466-1472.
Lwin, H.P.; et al. (2022). Perforated modified atmosphere packaging differentially affects the fruit quality attributes and targeted major metabolites in bell pepper cultivars stored at ambient temperature. Scientia Horticulturae 301: 111131.
Toledo-Martín, E.M; et al. (2015). Application of visible/near-infrared reflectance spectroscopy for predicting internal and external quality in pepper. Journal of the Science of Food and Agriculture 96: 3114-3125.
Vega-Gálvez, A.; et al. (2009). Effect of air-drying temperature on physico-chemical properties, antioxidant capacity, colour and total phenolic content of red pepper (Capsicum annuum, L. var. Hungarian). Food Chemistry 117: 647-653.
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From the one hand, the use of suitable solvents in the mobile/mobility phase coupled with sample preparation instructions, using the column and the detector related to the type of secondary metabolite and the degree of polarity and non-polarity of the solvent particles and the resulting bonds should be considered. On the other hand, having the standards of considered compounds helps the process of isolation and identification of compounds phenolics and flavonoids. Eventually, It should be noted that setting the appropriate temperature program and effective wavelengths (280-320) must also be applied till would be made the best result.
Regards
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I will use DFT calculation tool, MedeA VASP, for calculating Gibbs free energy of gas phase and solid phase.
I know that gas phase calculation using VASP may be uncorrect. But I can't use Gaussian because of the budget.
MedeA VASP Phonon module gives below data
1)Cv : vibrational heat capacity at constant volume 2)E_vib(T)=E(T)-E(0) : the change in vibrational internal energy from 0 K, where E(0) = E_elec + ZPE is the electronic energy of formation E_elec plus the zero point energy ZPE 3)S(T) : the vibrational entropy at temperature T 4)-(A(T)-E(0)) : the change in the vibrational Helmholtz free energy from 0 K 5)E(T) : the electronic energy of formation plus the vibrational internal energy, so this term is E_elec + ZPE + E_vib(T)
6)A(T) : the electronic plus vibrational Helmholtz free energy, E(T) - T.S(T)
and my questions are
1)How can I calculate Gibbs free energy for gases and solids from these data?
(I know that in a gas we can regard the internal energy as the sum of the electronic, translational, rotational, and vibrational energies. And We just get electronic and vibrational energy. Also, How can I consider PV term?)
2)How accurate is the VASP transition state and thermodynamic calculation for gas?
(I will calculate reactions for CVD reaction. ex)SiH4+SiH4->SiH6+H2, Si(wafer)+SiH4->Si+H2, etc.)
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As you mentioned it. The gas phase in VASP may be incorrect. An easy way to do the solid phase and gas phase could be:
1. Solid phase: compute the vibrational frequencies of the system. With that, you could calculate the enthalpy=U+KbT+H_vib., and then the Gibss as H-TS ( )
2. Gas phase: You could follow the tutorial of ORCA (free software: https://www.orcasoftware.de/tutorials_orca/prop/thermo.html). You must construct a good (and representative) model of your system in gas phase.
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Usually, plant phenols are best extracted with solvents like methanol and ethanol. But I would like to know if the extraction is carried out with water, how much usually is the efficiency of that extraction??
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alcohols like methanol and ethanol are the best solvents to extract phenolic compounds. but these can also be extracted with water but it depends on the part of the plant drug used (leaves, flowers, roots ........) you must also do a bibliographic research on the optimization of the various extracts used on your plant in order to obtain the best yield in polyphenols. good luck
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Irrational numbers are uncomputable with probability one. In that sense, numerical, they do not belong to nature. Animals cannot calculate it, nor humans, nor machines.
But algebra can deal with irrational numbers. Algebra deals with unknowns and indeterminates, exactly.
This would mean that a simple bee or fish can do algebra? No, this means, given the simple expression of their brains, that a higher entity is able to command them to do algebra. The same for humans and machines. We must be able also to do quantum computing, and beyond, also that way.
Thus, no one (animals, humans, extraterrestrials in the NASA search, and machines) is limited by their expressions, and all obey a higher entity, commanding through a network from the top down -- which entity we call God, and Jesus called Father.
This means that God holds all the dice. That also means that we can learn by mimicking nature. Even a wasp can teach us the medicinal properties of a passion fruit flower to lower aggression. Animals, no surprise, can self-medicate, knowing no biology or chemistry.
There is, then, no “personal” sense of algebra. It just is a combination of arithmetic operations.There is no “algebra in my sense” -- there is only one sense, the one mathematical sense that has made sense physically, for ages. I do not feel free to change it, and did not.
But we can reveal new facets of it. In that, we have already revealed several exact algebraic expressions for irrational numbers. Of course, the task is not even enumerable, but it is worth compiling, for the weary traveler. Any suggestions are welcome.
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We need to be optimistic, because that is the lesson from nature. An animal can self-medicate, obeying natural laws in chemistry that are unknown to animals. A tree grows when pruned, so we can see this pandemic as an opportunity. Let's grow, nature is not a zero-sum game!
Irrational numbers and mathematical real-numbers are uncomputable, with probability 1.
But irrational numbers can be calculated exactly in algebra a and that is how animals are able to calculate-- in a network of thoughts.
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In the following article's ESI, it seems that in situ decomposition of 2,5-Dihydroxy-1,4-benzoquinone (DHBQ) lead to the formation of oxalate under hydrothermal conditions.
Can someone explain the mechanism/pathway behind it?
Ref.: Science 374, 1464 (2021)
Please correct me if I am wrong by any chance.
Thanks in advance.
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You may also see the retrosynthesis pathway from scifinder
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I want to apply Post-doc Chemistry in Turkey. Can anyone suggest me a University in Turkey???
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Koç university, Sabancı university (more suitable for interdisciplinary subjects), Boğaziçi university and METU.
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Hello! What are the oldest literary sources you know that would mention pharmaceutical salts? I am aware of the first cocrystal [benzoquinone + hydroquinone] (1:1) investigated in 1844, but I could not find any mention of the first (or even the first described) pharmaceutical salt (Wohler, F. Untersuchungen über das Chinon / F. Wohler // Ann. Chem. Pharm. – 1844. – V. 51. – P. 145-163). If you know of such sources, please share them. Thanks in advance
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Interesting situation. As soon as I write a question here, I immediately find the answer. Here are some papers on pharmaceutical salts (responding to my comment above): 1) 10.1016/j.ijpharm.2021.120993; 2) 10.1016/j.jddst.2021.102913
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I would like to generate a *.sdf file like those posted NIST Chemistry Webbook from a *.log or *.chk Gaussian 16 file and cannot immediately find how to do this. Many thanks for helping me.
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Hi Ioan, Gaussview can help you.
Best wishes,
Quang
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Which software is best for making high-quality graphs? Origin or Excel? Thank you
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origin
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Mehlich-3, 20 L final volume:
0.2 M acetic acid (230 mL concentrated glacial acetic acid, ACS)
0.25 M NH4NO3 (400 g ammonium nitrate, ACS)
0.015 M NH4F (11.1 g ammonium fluoride, ACS)
0.013 N HNO3 (16.5 mL concentrated nitric acid, ACS)
0.001 M EDTA (5.85 g EDTA free acid, ACS)
Purpose: Soil nutrient extraction for boron, copper, zinc, phosphorus, iron, manganese, magnesium, potassium, calcium, and sulfur to be measured by ICP-OES.
Once all compounds are combined and dissolved, my Mehlich-3 extractant has a pH of approximately 3.2 instead of the pH 2.5 the SOP I'm following indicates the extractant should be. Should the unadjusted pH of the extractant be 2.5 and, if not, what acid would be appropriate to adjust the pH without impacting extractant performance?
Some preparation instructions suggest making a 3.75 M NH4F + 0.25 M EDTA free acid stock solution and adding a volume of that rather than adding NH4F and EDTA directly to the extractant as I'm doing above but I've never managed to get the EDTA to dissolve after dissolving the NH4F using that approach.
Thank you!
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Formic Acid maybe. It is used in LC-MS.
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Good day,
If anyone can assist me, please. How do you measure ammonium and nitrogen from urine? what is the best simple method for someone who is new in chemistry if you can recommend the site where I can find the experiment of measuring ammonium and nitrogen would really appreciate it.
Thanks
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Hello,
in order to determine ammonium, i find that the Nessler method of determining ammonium should be suitable for you. As suggested in Paul Milham's answer, it is a colorimetric assay. It has the advantage of being easy to perform (no need to heat, for urine there should be no need to correct the pH and the reaction is fast) and sensitive. Don't hesitate to ask if you have any questions. Good luck.
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How long does it take to a journal indexed in the "Emerging Sources Citation Index" get an Impact Factor? What is the future of journals indexed in Emerging Sources Citation Index?
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Clarivate announced that starting with 2023 ESCI-indexed journals will also be assigned an impact factor. See: https://clarivate.com/blog/clarivate-announces-changes-to-the-2023-journal-citation-reports-release/
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We can test an antagonist e.g. at 10uM with varying concentrations of agonist. We can then use Schild/gaddum equation to find a KD (also known as KB) for the antagonist.
If i was to change antagonist concentration to some other concentration like 100nM, but test with same agonist, will the KD calculated for the antagonist change or not
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The Ki value of a ligand is normalized by the affinity of the radioligand for the protein of interest (Cheng Prusoff equation). Likewise, the functionally calculated Kb value is normalized to the EC50 of the agonist and the concentration of agonist used (described by Cheng in the Power Issue article that Tomasz referred to). In this case, it's best to run the EC50 calculation for each independent assay as a control. As long as the IC50 is well defined by complete competition, the calculated Ki or Kb value should be robust and consistent across varying concentrations of radioligand or agonist.
Ideally, though, you wouldn't want a completely saturating concentration of radioligand or agonist (stick to ~Kd/EC50) to ensure full competition.
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If someone is granted with utility model can he/she claim it to be granted a Patent?
Is it legally acceptable?
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It would depend on the jurisdiction because patents are national rights as are utility models. Many countries don't have utility models and there are some which have what are called "petty patents" which are like utility models. I am only qualified to advise on UK law (and it would be a criminal offense under the UK Patent Act to mark a product so as to claim to have a UK patent if you didn't have a UK patent), but the rule of thumb for every jurisdiction must be to act honestly and reasonably. So if you have a German Utility Model then say you have a German Utility Model, if you have an Indian Patent Application, then claim you have an Indian Patent Application, etc etc
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Data augmentation techniques drastically improved AI models while dealing with images and text, however, it is not so obvious how to translate these approaches to chemistry and materials science. What methods do you know and how legal do you think they are?
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When I was looking into data augmentation techniques, I came across SMILES enumeration for molecules.
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I have some flyash and want to leach out Al2O3 and SiO2 using NaOH. IS there any additive which can help me to improve rate of leaching or dissolution .
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Under some circumstances there are a few organic acid ions such as oxalate, glycolate that marginally assist in silicate leaching but I am not sure if they would work in your case. However, if you find nothing else, they might be worth investigating.
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We talk about the round oval shape objects. Grid is 15 um. We supossed some kind of drug crystals, but patient has no special medication.
Chemistry:
blood 2+
leukocytes 2+
pH 7.0
SG 1.009
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Fat droplets? Check with polarized light. https://www.labce.com/spg2087066_oil_or_fat_droplets.aspx
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Hello everyone. I need a little help here.
can we use essential oils to reduce chlorinous odor in a hypochlorous acid solution without decreasing free chlorine or pH value? any toughts and propositions are much appreciated
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The reduction in odor is likely due to chlorination of essential oil constituents. Why are you using hypochlorite? As biocide pH should be ~6.5. Are you measuring av Cl ?
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Hi, I need to make an optical window 0.5 - 1mm thick and 6 mm in diameter from PMMA. I would really want to master the skill of production instead of buying some slug or film sheet because later would need to modify the shape ( make a wedge instead of a plane window ) and so on.
I am planning to make a mold using a 3d printed circular part ( see the drawing attached ) wedged between two microscope slides.
We gave it a try and made a sample, but at that time we didnt have the vacuum chamber and poured the pmma into the could mold. ( see the picture attached )
The problem is that the fist sample was quite large and separated from the glass rather easily, which is not the case for smaller sample. The second problem is bubbles.
Could you please suggest the exact step by step scheme to follow ( the concentration, temperature mode, time frames and so on ) to improve our results and obtain bubble free sample which can be safely parted from the mold after the hardening.
What I have:
1. Methyl methacrylate (CAS Number: 80-62-6) from sigmaaldrich
2. Azobisisobutyronitrile (CAS Number:78-67-1) from sigmaaldrich
3. magnetic stirrer hot plate, beakers, vacuum chamber, heating chamber
Thanks a lot in advance.
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Hello Georgy,
the first step is to produce a prepolymer with short chains of pmma. You have to figure out your iniator yield to get reproductive bubble free polymers. There are numerous literatur about these topic. At first glance I would recommend a smaller amount of AIBN for prepolymerisation and a thorough degassing of the slightly thickening batch (stirring, vacuum, cooling, ...).
With best regards
Carsten
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I have synthesized cerium oxide nanoparticles (CeO2 NPs) using the combustion method. My attempts to functionalize the NPs using the APTES have failed so far. After APTES functionalization, the particles are not stable; they settle rapidly. I would greatly appreciate it if someone could propose a solution and reason to the problem.
#Nanoparticles #chemistry.
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Before functionalizing your nanoparticle, you must expose your nanoparticles to a flux of NH3 (Ammonia) to create hydroxyl groups (OH) on it. After that, it will be easy to functionalize your silane ATPES.
good luck
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Hello Scholars,
I am an undergraduate at the University of Cross River State, Nigeria currently pursuing a microbiology program. For familiarity and enhanced understanding of the course, I wish to seek recommendations on the virtual/simulation laboratory software that would be very helpful to me and my colleagues. With my interest in research too, I will be pleased if a research simulator is recommended to help widen my understanding of Microbiological research.
Your recommendations would go a long way to significantly contribute to my academic career as well as my colleagues.
Thank you
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Thermofisher Scientific has a virtual lab training option on cell culture. You can check here: https://www.thermofisher.com/bd/en/home/global/forms/cell-culture-basics.html
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I'm finding some cationic molecules like below.
I tried finding on www.sigmaaldrich.com , but couldn't find anything.
Where can I buy some molecules like this?
ref)Ikeda, Taichi, and Yoshitaka Matsushita. "Tetrahedral Tetra-cationic ionic liquids." Chemistry Letters 49.1 (2020): 14-16.
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if you got the cas you can try http://www.chemexper.com/ they search over different chemical companies, but such kind of systems can get quite expensive.
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I will be working on a slow-release fertilizer for my undergraduate thesis, but I am confused about how other authors measure cumulative nitrogen release for a time interval (including the instruments and calculations)?
More exactly how they measure the exact nitrogen released each time.
Please provide a step-by-step process for a rapid water test.
-Thank you for helping a chemistry student.
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Not something I've done but the idea is to have a stirred cell which contains the fertiliser suspended in water, and continuous/timed sampling connected to an analysis system (e.g., spectrophotometer, conductivity cell ....)
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I wonder if the removal of pi bond and the addition of heteroatoms such as halogens would increase or decrease the energy gap between the ground state and excited state of the electrons.
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After the first step of an electrophilic addition reaction an intermediate (carbonium ion) is formed (with a much higher energy). There are no more pi-electons.
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We are living in a world where recently Artificial intelligence is being used in many applications for prediction of many events and things. We all know that the amount and balance of certain Chemicals in the brain have a role in causing us think creative , feel emotional or happy etc. I would like to learn the valuable opinions of Scientists on what specific roles Chemistry would have in creating human conciousness ?
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Thank you Jerry, very helpful reference and information
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Salt has an ionic bond. It's chemically bonded. So, when it dissolves in water, the ionic bond is somewhat lost. But, people argue that it is a physical change because-:
a) The mixture of salt and water can be separated by evaporation.
b) No new substance is formed.( how though? isn't salty water completely different from just water or salt alone?)
c) There is no energy produced. (but then again when we tear paper, the ripping creates some energy...so how is there no energy in a physical change?)
Thank you in advance,
B.P.
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Dissolution can cause hydration reaction with creation of charged and uncharged complexes. Example: gypsum dissolution
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thanks in advance on sharing the method
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Please find the attached article - Determination of Chloride Content in Cementitious Materials. (It may be helpful)
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I am evaluating the options, especially in the true open-source world, for making reliable calculations with high-accuracy using quantum correlation methods.
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You might want to consider ORCA or PSI4 depending on what you want to do. ORCA is very good for high accuracy correlated methods.
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I synthesized a molecule. I want to know what are the self-assembled structures possible for it through hydrogen bonding.
If possible, please suggest me some free software available (installation-based or online)
Any relevant suggestions are highly appreciated. Thanks.
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Using GROMACS to perform molecular dynamics simulation is a very good choice. GROMACS is quite fast, flexible and meantime freely available.
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Hello, I recently discovered via GC-MS that my sample contains crown ether. This was really unexpected. I would like to know how to isolate these compounds for further analysis. I appreciate any paper suggestions or personal tips!
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In aqueous media? I'd try solid phase extraction onto reverse phase. Wash with water, then wash with steps of increasing concentration of acetonitrile in water.
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Who is your nominate for the chemistry and physics Nobel prize?
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My guess in the field of tissue engineering is Robert Langer from MIT. For the Chemistry Nobel Prize.
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Chemistry question: I've received compounds to dissolve at 10uM. They sent MW, FW, and mg amts for each. Some cpds MW=FW, but others have "salts" added, and those have FW>MW. Should I use MW or FW to convert the mg amt to moles for calculations to achieve uM solutions?
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It depends on what the experiment is determining. For instance if the experiment required analyzing perchlorate (anion) and you were given sodium perchlorate salt to dissolve you would need to "subtract" the sodium to determine the uM concentration of perchlorate anion in the solution. In the above example if you were not to correct for the salt and just used the MW to determine perchlorate concentration in your solution you would be ~19% off. 0.1231g of NaClO4 is equivalent to 0.1000g of ClO4 anion. So it makes a big difference - especially if you are using the solution for an analytical standard, or for instrument calibration. We could dive into this deeper if you gave us more information. You can always calculate it both ways as well, unless the experiment requires a specific concentration - then you would need to know up front if you should prepare the solution based on the anion concentration.
regards and hope you come up with the correct solution :)
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Please Suggest me research topic for bachelor degree of chemistry
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Nischal
Do you have a mentor/professor to guide you? You should!
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self‐assembly in the crystalization process.
The origin and the first study in the field of self‐assembly
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Dear Mohammad,
I suggest to clearly define what you mean by "self-assembly".
The problem is that this term has been very often used in completely non-specific way, just to boost the importance of a paper or report. I call this buzz-wording. Imho this term should not be used for:
1) the assembly of ions in a crystal lattice
2) any simple bond formation of a coordinative or covalent bond
Personally, I find the term "self" misleading as in many cases, the researchers are driving the assembly clearly in just one way. Or there is only one way of aggregation of the ions or molecules.
I would use the term "selective assembly" if there are more than one possibility to form an aggregate or a crystal or a complex and one way is selective over the others.
If there is only one way how the particles (ions, ligands, molecules) can assemble, then there is no extra word like "self" needed, and we should call this specifically "coordination", "forming of H bond", "crystallisation" depending what forces finally keep the particles together.
Best
AXEL
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Hello everyone, I have a question about COD (Chemical Oxygen Demand) electrolysis of organic compounds. When doing the COD analysis of the initial sample before treatment, why did it produce a high COD level? what factors in the COD level caused the initial COD level to be very high?
Meanwhile, after being electrolyzed (after treatment), the COD level decreased, what caused the COD level to decrease and were there any structural changes that occurred related to the reagents in the electrolysis process (organic compounds, electrolyte, additional H2O2, COD reagents) .
So, for example, the sample is acetaminophen
Before treatment (acetaminophen + aquades), why was the COD level of the acetaminophen sample so high? what causes the high value? and why after treatment, the COD level of acetaminophen decreased? what causes the COD level of acetaminophen decrease? Are there any structural changes that occur in acetaminophen related to the reagents associated with the electrolysis process after treatment? if there is a change, what kind of change and how?
Thanks in advance.
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