Science topic

Powders - Science topic

Substances made up of an aggregation of small particles, as that obtained by grinding or trituration of a solid drug. In pharmacy it is a form in which substances are administered. (From Dorland, 28th ed)
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When dealing with the fabrication of Ceramic membrane using Fly Ash & Clay or Kaolin, using sodium silicate as binding agent it breaks & turns into powder at room temperature after sintering at 800°C. Which binding agent is suitable to avoid the turning of membrane into powder form after sintering?
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Exactly, that's what we have not covered. As the calcination also helps in greater binding strength later on along with impurities removal. Thank you Sir for providing valuable answer & filling on my gap..
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Hi all,
I am working on creating my complete media for VSMC. I have to reconstitute 50mg of ascorbic acid in 10ml H2O (or base media) and then add 2.5ml into my final volume of 250ml complete culture media. How do I ensure the ascorbic acid is sterile when adding to my media after weighing out the product and dissolving the powder into solution?
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Hello Ashley,
After having prepared 50mg of ascorbic acid in 10ml sterile H2O/ base media, filter sterilize the ascorbic acid solution using 0.22 μm syringe filter and then add 2.5ml of this sterile ascorbic acid solution to the final volume of 250 ml of complete culture media. This will ensure that the ascorbic acid is sterile when added to the media.
Best.
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how i can droplet liquid binder into particles powder during ANSYS fluent
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What problem are you having in ANSYS with the VOF (Volume of Fluid) model? You can clarify details such as the type of simulation, dimensions, or error messages you are seeing, and I will help you as much as I can.
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Cerium oxide are predominantly used for the polishing powder. Do we have any other available composite or engineering materials which can be used to achieve these fine polishing of glass surfaces efficiently?
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Borosilicate glass when reexamined has been found to have the tendency to be grinded into very fine particles of very nano particles in nature when blended with enough quartz has a capacity of polishing the surfacess of optical wares.
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If I synthesize Nickel doped ZnO powder (powder & thin film) by sol-gel method, by those samples which applications I can target? All scientific answers/explanations are highly appreciated. Thank you!
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Nickel-doped ZnO (Ni:ZnO) materials, whether in powder or thin film form, have a variety of applications due to their unique properties.
  1. Transparent Conducting Electrodes: Ni:ZnO thin films are used in devices requiring transparent electrodes, such as touch screens and solar cells.
  2. Spintronics Devices: The ferromagnetic properties of Ni:ZnO make it suitable for spintronics applications, which utilize electron spin for data storage and transfer.
  3. Photocatalysts: Ni:ZnO is effective in photocatalytic applications, such as in environmental cleanup and water treatment.
  4. Gas Sensors: The material's sensitivity to gases makes it useful in gas sensing applications.
  5. Light Emitting Diodes (LEDs): Ni:ZnO can be used in LEDs, especially for near-infrared light emission.
  6. Biomedical Applications: Due to its antibacterial properties, Ni:ZnO is used in some biomedical applications, such as wound healing and drug delivery.
Kindly go through some literature for further clarity.
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I have synthesized carbon dots from banana peels and I am unable to obtain completely dried brown powder (as read in literature). It is very oily even after oven drying and freeze-drying. Can anybody suggest what may be reason and how to obtain the carbon dots in powder form?
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Thank you Roopkumar Sangubotla . But I have tried this too, this also yielded oily substance
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I have a gas atomised powder. I want to use it in laser powder bed fusion. I will use vibratory siever to sieve the powder. What sizes of sieves do I need?
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For sieving gas atomized powder for laser powder bed fusion, use these sieve sizes:
  1. Mesh 40 (425 µm): Removes oversized particles.
  2. Mesh 60 (250 µm): Captures larger agglomerates.
  3. Mesh 80 (180 µm): Refines powder size.
  4. Mesh 100 (150 µm): Ensures optimal particle range.
Consider a finer sieve (like Mesh 200) for very fine particles if needed. Adjust based on your specific powder and application requirements.
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I am working on a project on culture of protease producing bacteria
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Please, could you tell me the recipe you use for milk agar plates ? I mean directly, not a reference to publication.
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I want to measure the oxygen concentration in Aluminum oxide powder in ppm. Can anyone suggest how it can be accurately measured?
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Hello there.
You can use the inert gas fusion technique, which allows you measure the O2 concentration. I've used LECO brand equipment, but I'm sure there're other options too. The drawback is that it will burn your samples. I hope you'll find a solution.
Best,
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Hello colleagues,
I am currently working on the development of soil stabilization techniques using metallic tailing powder as a key component. I have completed a research article on this topic and am looking for collaborators or experts in the fields of soil mechanics, geotechnical engineering, or materials science to review and provide feedback on my work.
If anyone is interested in collaborating or reviewing the article, I would greatly appreciate your insights and suggestions to enhance the quality and impact of the research. Please feel free to reach out to me. Thank you!
Best regards,
Wisal Ahmad
Institute of Urban Environment Chinese Academy Of Sciences.
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Wisal Ahmad I am willing to collaborate with you on this but I also agree with Bashar Alibrahim
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Since the requirement of desired phytochemical in larger volume for various analytical process which requires higher amounts of certain sample in a pure state. Hence, i need to know how much of powderized, crude sample has to be loaded in the thimble to be condensed and obtained as pure sample in concentrated state.
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When 15 to 20 grams of plant leaf powder is placed in the thimble, the final yield after fully evaporating the solvent is typically only 3-4 grams of extract.
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Dear friends, what size of copper powder is suitable for forming alloys with other metals for use in the HMFOR coupled with CO2 reduction? Which transition metal makes alloys with copper powder for this application?
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Hi Elmineh, sharing of my past learning, FYI.
My suggestion for you is begin with a directional-matrix study on
the 'Mixed Ratio' of diff. sizes, such as Big/small ratio; but not a single size alone.
To exam & select the prefer performance Ratio of mixed-sizes.
Following to design the details of what is best fit into your experimental scale.
Good luck.
Cheers!
DA
===
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I prepared a graphene using Sonication assisted LPG. and this is a raman spectrum for a powder sample of this graphitic material, how can i estimate the number of layers using the 2D band Data?
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If I look at this, it looks like it has only 5-6 data points per peak. I would be fine with a coarse peak intensity ratio from this, but I wouldn't use this for shape analysis.
Here you see the degree of detail required for a shape analysis:
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I mixed tungsten and titanium and sintered it in cylinder shape diameter 50mm with thickness 4mm. I would like to observe the fracture morphology under SEM. But to study the fracture morphology first I need to break it. WTi is very hard material. I unable to do tensile or compression test to break as the sample is too small. Is there any way to break it like using chemical or how? In published paper they do not mentioned in details how they break it.
Thank you in advance,
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Jp Wu Nice suggestion. Thank you for your reply.
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Powder samples are likely to contaminate the chamber and damage the pump possibly during pumping and venting steps. Is there a way to prepare powder samples so that they can be processed in the RTP system?
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Можно незначительно увлажнять порошковую смесь, а затем это вещество возгонять при термообработке( спекании).
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Hi, I'm currently working with salmonella biofilms and the pure culture is enclosed in a freeze dried powder, can any one suggest how I can suggest how I can achieve this?
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chicken powder and wheat flour based baked sticks
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The shelf life of chicken powder-based baked products, like baked sticks made with wheat flour and chicken powder, varies based on:
  1. Ingredients: Quality and type of chicken powder and other ingredients.
  2. Packaging: Proper, air-tight packaging can extend shelf life.
  3. Storage Conditions: Cool, dry storage conditions are ideal.
  4. Preservation Techniques: Use of preservatives and stabilizers.
General Shelf Life:
  • Unopened Packaging: Typically 6 to 12 months.
  • Opened Packaging: Generally 1 to 3 months.
For accurate shelf life, conduct stability tests, including microbiological, sensory, and chemical analyses. Consult food scientists for precise evaluation.
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Dear Colleagues,
Here, I need your consideration in choosing the results of FTIR results. Since, I have some raw data on my materials (clay powder based photocatalyst), I got the FTIR without treatment, baselined, and ATR. Which one should I choose for graph plot? This is my first time use ATR-added FTIR instrument.
Thank you for your time.
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Dear Mr. Abdul Zahir
Thank you for the answer. Unfortunately, I want to know more about: what the most important data should I chose between these two (only baseline and ATR mode), if i have analyzed the samples only with baseline mode and ATR mode?
I am looking for a respond from you.
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Hi there, I am trying to coat a 96-well round bottom plate with poly-HEMA as part of my spheroid assay protocol. I dissolved 20 mg/ml of poly-HEMA in 95% ethanol and added 100 microliters of this suspension to each well.
The protocol I am following recommends to leave the plate to sit in the tissue culture hood (sterile) at room temperature for 24 hours or in the 37 degree celsius incubator for 24-72 hours with the lid ajar.
When I tried this, the outside wells had dried up to the point where we could see white powder residue at the bottom of the well. The inner-most wells were still in solution and had not dried.
I threw this plate out and tried again, this time with the lid on during the drying time, as opposed to ajar. It has been 3 days and we still do not see any drying occuring.
What does the polyHEMA-coated wells look like when optimally dry? How do you know when the polyHEMA has dried and the plate is ready for cell-seeding? How do you dry the plate so that all wells are drying at a constant rate?
Thank you in advance!
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Hi, make sure all Polyhema crystal mixed well in ethanol. After adding polyhama heat the mix and when you see bubble ghen shake for 10 seconds and repeat until all crystal disolve perfectly, and once you put polyhema in the plate, make sure its cover the whole plate and keep the plate at 55 Degree Celsius shaker oven for over night to completely eveporate the solvent. Then you got uniform plate with no residues,
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dispersion of silver nanoparticle powder
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You can disperse nanoparticles in your essential oil. It seems that you have problems with the stability of the suspension. Make it more viscous by adding a polymer that will not spoil other desirable properties of the suspension.
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What qualitative analysis i need to perform before doing the quantative analysis?
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I act in this way:
  1. Checking and getting to know the data
  2. Coding and categorization
  3. Theme development
  4. Identify relationships and patterns
  5. Validation and triangulation
  6. Background analysis
  7. Development of theory or application
  8. Data reduction
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I saw in an article that the prepared plant aqueous extract was filtered with a suitable filter paper and then diluted to a certain extent and used directly in experiments. Of course, it is normal to work this way. However, is it correct to express the results in μL/mL? However, how could they have calculated how much to dilute the aqueous extract since it was used directly in the experiment, because a stock solution was not prepared since the extracts were not in powder form?
I also saw such a procedure in another study: "2 g of the plants were weighed and 100 ml of distilled water at 100 ° C was added to them and left to infuse for 10 minutes. After the infusion process was finished, it was filtered through filter paper and the supernatant part was stored at 4 ° C for use in experimental studies." However, while doing the experiments, how could this liquid extract be prepared in concentrations of "1 ml of plant extract with concentrations of 50, 250, 500, 750 and 1000 μg/μl" and 20 µl of plant extracts (0, 10, 50, 250, 500, 1000 µg/ml) in these ratios? Because this extract is in liquid form, so in order to dilute it in µg/ml, doesn't it need to remove the solvent of the extract and turn the extracts into powder?
I am asking these questions because I will be conducting a study on herbal teas and will be using the tea extracts I have prepared in liquid form. Therefore, I need to know the correct method for their use.
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In the context of bioactivity studies using aqueous plant extracts in liquid form, it is imperative to consider the appropriate expression of concentrations and the preparation of test solutions. It is common practice to process plant extracts without evaporating the solvent, thereby maintaining the extract in a liquid state. In such cases, it is appropriate to express concentrations in microlitres per millilitre. This unit represents the volume of extract added to a given volume of medium, which is common practice when testing liquid extracts directly without isolation of individual bioactive components.
A major challenge is the accurate preparation of these extracts for experimental use, particularly when concentrations need to be expressed in units such as µg/µL or µg/mL. Regardless of the liquid state of the extract, dilution to specified concentrations can be achieved without converting the extract to a powdered form. This is known as serial dilution, where the initial extract is treated as a concentrated solution and diluted progressively with water or an alternative solvent. Such dilutions are straightforward when working with volume-to-volume (v/v) ratios, commonly expressed as microlitres of extract per millilitre of solvent.
It is of utmost importance to quantify the dry weight of bioactive compounds in the liquid extract in order to express the concentration in µg/µL or µg/mL. This can be achieved by chemical analysis methods such as gravimetric analysis, spectrophotometry or chromatographic techniques that determine the concentration of specific compounds in the original extract. In the absence of precise knowledge of the mass of bioactive compounds, the concentration can be estimated on the basis of the total soluble solids or active constituents, which can be measured directly in the liquid extract.
For example, if chemical analysis indicates that 1 mL of the liquid extract contains 1000 µg of bioactive compounds, subsequent dilutions can be made accordingly. To prepare a solution with a final concentration of 100 µg/mL, 0.1 mL of extract must be mixed with 0.9 mL of solvent. This approach ensures that accurate and reproducible concentrations can be achieved for bioactivity assays, even without drying the extract.
In summary, when working with liquid extracts, it is both appropriate and widely accepted to express results in µL/mL. However, conversion to µg/ml or similar units requires prior quantification of the active components in the extract. To ensure accurate and consistent experimental conditions, especially when dealing with complex herbal infusions or tea extracts in bioactivity studies, it is essential to employ proper chemical analysis and to follow careful dilution protocols.
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Please explain micro carbon technology?
I have illustrated how Activated carbon works.three types powder, granular and micro carbon
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Microcarbon of 1-100 µm size can be obtained in various mills from ordinary activated carbon.
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Hello,
I am trying to spray dry my material (hydrophilic) using PVA, but yield is the problem. During drying, my PVA material is sticking inside the drying chamber as it as film forming property. Can anyone help me how to avoid this and increase the yield of powder in cyclone?
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The answer to this question is very simple: the atomized droplets may only reach the walls of the tower when they are dry.
In industry, this is achieved by making the tower large, but laboratory systems are far too small to allow the droplets to travel a long distance.
If you have a small tower available, the only option is to optimize the spray nozzle to produce smaller droplets and lower productivity. A high temperature in the upper part of the tower can also help a little.
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what methods/ analysis does it include?
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One can get information from qualitative analysis in powder XRD including crystallographic information.
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In my lab, we receive dry DNA constructs in a 96 well format plate. We resuspend the DNA using a pipette, adding solvent down each row. I want to use an instrument with a 96channel head to dispense solvent into all the wells at the same time, with tips hovering over the wells instead of dipping into the wells, so that I may re-use the tips. I need to check for splashing or well-to-well contamination due to the use of this instrument.
My idea is to use a powdered form of fluorescein sodium salt, put it in a 96 well plate in a checkerboard format, use the instrument to dispense solvent into all the wells, ensure the dye is dissolved, and then use a plate reader to check for absorption or fluorescence between the wells with dye, and blank wells. Does this experiment make sense? If there is no splashing or well to well contamination due to the 96channel head, I should expect to see fluorescence/ distinct absorbance maxima for the wells with dye while those with only solvent, should not have fluorescence/ different absorption peaks. Also is there a good way to measure out equal but quite small quantities of this dry powder form dye into a plate.
Basically, I need to resuspend a dry material and then take some sort of measurement between blanks/controls and the resuspended material and I need to test this cheaply.
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Continuing on Adam B Shapiro answer I will suggest going 10-fold to 100-fold higher in the wells containing fluorescein in the beginning and adding a buffer to the ones that don't. Simply because if a splash occurs it will be of small volume.
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Typical mold powder compositions(wt%) are given as
SiO2=33, CaO=20, MgO=1.5, Al2O3=6.0, Na2O=10.5, K2O=1.5, Fe2O3=2.5, MnO=0.1, Cfree=20.5, CO2=6.5, Ctotal=22.0, F=5.0.
For estimating CaF2 wt% in mold powder, should I calculate stoichiometric CaF2 based on F wt% present in mold powder.
If yes, than CaO wt% have to reduce to compensate Ca present in CaF2.
In that case, basicity of mold powder also decreases since CaO wt% will reduce.
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Hello,
CaF2 is formed according to the stoichiometric ratio between F and Ca. This is 2.05 times by %weight. So, 5% F means 10.27 % CaF2. Due to Ca bound as CaF2, the amount of CaO decreases and becomes 12.62%.
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I run mechanochemical reactions that involves the use of a large amount of catalyst (1:1 molar ratio to the reactant). When I try to understand the effect of amount of catalyst on the reaction, I find it very hard to get consistent results when I control the the ball to powder mass ratio (I am using the same number of balls, but keeping the total powder mass the same while adjusting the mass between the reactant and catalyst). This makes me think that I should probably control ball to powder volume. However, even though I know the rough bulk volume of two things at the beginning, the powder volume will always increase by an unknown amount once it is milled. So how should I control my reaction??
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It is not easy to define the controls of your reaction. Don't think you can use a simple control or two to define your experiments. Breifly, you should consider the controls of mass, volume, particle size distribution (PSD), surface property (not all inclusive) of catalyst and reactant, as well as their ratios to define your reactions.
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I am searching for HPLC method to estimate Mirtazapine but i want to avoid HPLC-buffers as a mobile phase component. So, I am looking for alternative HPLC-solvent (acetonitrile, methanol etc.) mobile phase.
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Try using ACN, MeOH, Water with pH modifires like TFA, Formic acid, OPA, Ammonia, Acetic acid (all HPLC/LCMS Grade). pH modifires conc. starting from 0.05 % either in single or both mobile phases. Also, make sure which column you are using, Normal or Reverse C18.
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I am working on powder metallurgy, and during the compaction process, the powder does not pelletize and remains in its powder form. To address this issue, I am considering using binders to improve the compaction process.
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Syed Abbas Raza Im using uniaxial pressing with max 500 MPa. Thankyou for the tips and info! This is very helpfulll
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What is the value of the elastic modulus for marble dust powder and rice husk ash?
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the exact elastic modulus values for marble dust powder and rice husk ash are not typically measured in isolation, their inclusion in composite materials like concrete can significantly enhance the composite's mechanical properties, including the elastic modulus.
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I have to compare the FTIR of the two samples, one is in powder form and other one is the powder dispersed in IPA or water. Both are same material, so how the bond will change
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if powder was dispersed not dissolved in the carrier medium, the bond structures by FTIR should be the same, but with some extra peaks of the dispersed sample, i.e. from the carrier molecules.
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except liquid nitrogen, how to make plastic powder?
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Without cryogenic a plastic pulverizer machine, also known as a plastic mill or grinder, is a mechanical device used to grind plastic materials into fine powders or particles of course you can make powder from plastic or change plastic to powder into different particle size by hashing plastic and crushing otherwise the powder metallurgy is process which is used to change the shape of metal from powder to part according to die of forming. The plastic polarizer machine are available in various size depending upon the requirements.
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I am trying to load curcumin emulsion in 4% chitosan gel but i don not know how many mg powder is needed ?
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The authors of the article did not report the content of curcumin in the emulsion with Tween (surfactant). Apparently they think this is their trade secret. Therefore, you need to select the concentrations for the study yourself.
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Good evening, I would like to evaluate the heavy metal content in bird feathers. Can I keep my samples in powder form ? and can I use other tubes than Teflon for digestion?
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I'm asking because I can't get the teflon tubes, so I'm looking for something to replace them with. Thank you for your answer.
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Need an exact or approximate percentage of water absorption for marble dust or powder and Quarry dust compared to fine aggregate.
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I humbly request an answer to this question. Why is the water absorption rate for quarry dust (0.60mm) higher?
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fiber powders will be used as a reinforcement.
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Yes, polystyrene can be used as a matrix in a hybrid composite. Polystyrene, being a versatile and widely used polymer, offers several advantageous properties such as ease of processing, good mechanical strength, and chemical resistance.
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I am using fibroblast growth factor, purchased in powder form.
What suitable substance should be added to get it in a liquid form? Thanks
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excuse me. Icant help you this question. because I study on powder metalurgy and stress analysis and manufacture and CAD/CAM. If any quetion on this area or another I can help you. yu can sand me email or watsapp +905355164982
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We have been lyophilizing several nanoparticles like iron oxide, cerium oxide to get powder sample. However, for gold nanoparticles and any other NPs with gold, they turn sticky after lyophilizing instead of forming powder. Literatures mention they took XRD but I didn't find much on how they prepared the powder sample. One of the literatures suggested using filter paper but nothing really collected in the filter paper when filtered. Any suggestion on how I could get powder GNP for XRD?
Thank you!
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Shaila Thakur I'll try centrifuging the GNP. I've performed XRD with the sticky material and I can see a bulk gold phase but there are many additional peaks that I cannot account for. Thanks for the suggestion.
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After finish the synthesis of nanoparticles.and nanoplates of silver how to take out those as solid/powder form from the solution. Please give a solution of u already done that and succeeded by that
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Use centrifuge to separate the solids form liquid and dry it.
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I synthesise intermetallic compounds through nickel and aluminium powders. But the pure powder after synthesis is difficult to obtain. Especially the presence of aluminium oxide very seriously affects the purity of intermetallic compounds. I tried to pass hydrogen during the synthesis to make the aluminium oxide to be reduced. But aluminium is known to be more reducing than hydrogen. Unless hydrogen is plasma. So how do I reduce aluminium oxide.
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The problem with dissolving aluminum oxide using acids is that the metallic components of the mixture are dissolved in these acids before the aluminum oxide.
The only solution to the problem of Al2O3 contamination, in my opinion, is to reduce the formation of this contamination during powder synthesis. Two things help with this: the best possible vacuum or the purest argon (better than 99.999%). Adding hydrogen is counterproductive because it cannot reduce Al2O3 and is usually not as clean as argon (hydrogen with a purity of over 99.999% is very expensive and is rarely available). In contrast, "normal" hydrogen with a purity of 99.5% brings with it far too much oxygen, which causes additional Al2O3 formation.
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Hello,
I have bought some mitomycin C in powder. On the instructions, it is said first to dilute the powder in a few drops of ethanol, then in the solvent of choice. But there are many options.
Can I directly dissolve the powder in ethanol (concentration of 1 mg/mL)? Would the solution still be usable? Or is there a better solvent?
Can the solution be stored at -20 degrees?
Thank you
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Dear Michael
How long it can be stored at -20 if I dissolve in water? Thanks
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Hello, there,
I'd be interested in the particle powder made from PEG 1500 or other solid-like form of polyethylene glycol with low temperature of melting.
Do you know any companies fabricating such a powder or you are able to fabricate it in the laboratory scale for the research?
Thanks in advance!
Rafał
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My gut feeling is that you could try to freeze it followed by grinding, provided there is no concern of properties affected by this treatment.
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I am trying to obtain the instrumental broadening from my XRD equipment, and before buying a LaB6 NIST standard I wanted to try the KCl method from Scardi et al (1994). This method consists on sieving the KCl and treating it thermically to obtain a useful standard.
Regarding this I have two doubts:
  • How can I check if the KCl sample I have analysed is suitable for the instrumental broadening removal?
  • Do you think this procedure (done in the paper for a Bragg-Brentano geometry) is suitable also for GIXRD?
The software I am using is the HighScore Plus.
Reference:
Scardi, P.; Lutterotti, L.; Maistrelli, P. Experimental Determination of the Instrumental Broadening in the Bragg–Brentano Geometry. Powder Diffr 1994, 9(3), 180–186. https://doi.org/10.1017/S0885715600019187.
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Khagesh Tanwar thanks! I'll check it out, sure Si NIST standard is a good choice for my research.
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I am currently using API4000 from SCIEX and I have a problem with some unknown contamination.
I can see some white powder surrounding the orifice of the curtain plate and some unknown powdery stuff on the inner surface of ion source housing.
We are suspecting that the powder / contamination is from the water because the mobile phase filter in the water mobile phase is turning yellow pretty quickly. But we've been using the same HPLC grade water for years, and it's our first time having this issue.
Can anyone please tell me what the possible causes are?
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Dirk Siekmeier Have you tried using deionized water? I always thought HPLC grade water is cleaner than distilled water.. Maybe I should try using distilled water!
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I would like to do an insilico study in a medicated milk. So planning to do LCMS for identifying the phytoconstituents of the same. But the experts suggested to extract the protein and fat portion and do the LCMS. Is there any other methods to use the medicated milk as a whole for LCMS. Is it possible to use the formulation as a lyophilized powder and reconstitute it with methanol for analysis?
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Thank you so much for giving me a clear answer.
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When using the absorption spectrum to determine the absorption coefficient (Alpha), do the calculation methods differ between powder samples and thin films? If there are differences, what are the main distinctions in the methods used for each type of sample? How is the absorption coefficient (Alpha) calculated from the absorbance for both powders and thin films? Please explain the key considerations and techniques used in the analysis for each type of sample, including how to handle optical interferences and the effect of sample thickness in thin films compared to powder samples.
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Yes, the methods of calculating the absorption coefficient (α) from absorbance can differ between powder samples and thin films due to differences in their physical properties and how light interacts with these materials.
Absorption Coefficient (α) Calculation
General Formula
The absorption coefficient (α) can be calculated using the Beer-Lambert law:
A=α⋅d
where:
• A is the absorbance (dimensionless),
• α is the absorption coefficient (cm−1),
• d is the thickness of the sample (cm).
From this, the absorption coefficient can be derived as:
α=A/d
Thin Films:
For thin films, the calculation is more straightforward because the sample thickness is usually well-defined and uniform.
Key Considerations for Thin Films:
1. Thickness (d): Precise measurement of film thickness is crucial. Techniques such as ellipsometry or profilometry are often used to measure thickness.
2. Optical Interferences: Thin films can exhibit interference effects due to multiple reflections within the film. These effects can create oscillations in the absorption spectrum. Careful analysis is needed to account for these interferences.
3. Refractive Index: The refractive index of the film and the substrate can influence the absorption measurements. Knowing these indices helps in correcting for reflection losses.
4. Uniformity: Ensuring the film is uniform across the sample area to avoid variations in the absorbance measurements.
Powders:
For powder samples, the situation is more complex because powders do not have a well-defined thickness and light scattering plays a significant role.
Key Considerations for Powders:
1. Effective Path Length (d): The effective path length in a powder sample is less well-defined than in thin films. It can be estimated using the packing density and the sample thickness, but it's an approximation.
2. Scattering: Powders scatter light, which complicates the direct application of Beer-Lambert law. Scattering needs to be accounted for, often by using integrating spheres to measure diffuse reflectance and transmittance.
3. Sample Preparation: The sample's homogeneity and packing density can influence absorbance measurements. Ensuring consistent sample preparation is essential.
4. Kubelka-Munk Theory: This theory is often used to analyze the absorption of powders. It relates the reflectance and absorption coefficients, accounting for scattering:
K=αS
α= (1−R)^2/2R
where:
• K is the absorption coefficient,
• S is the scattering coefficient, and
• R is the reflectance.
Techniques for Each Sample Type
Thin Films:
• Spectrophotometry: Direct measurement of transmittance and reflectance.
• Ellipsometry: Provides thickness and optical constants.
• Interference Correction: Analytical or numerical methods to account for interference effects.
Powders:
• Integrating Sphere: Measures total transmittance and reflectance, reducing the impact of scattering.
• Diffuse Reflectance Spectroscopy (DRS): Analyzes the reflected light from powders to determine absorption and scattering.
• Kubelka-Munk Analysis: Converts reflectance data to absorption coefficients.
Practical Steps for Calculation:
Thin Films:
1. Measure the absorbance spectrum using a spectrophotometer.
2. Measure the film thickness using an appropriate technique.
3. Correct for any interference effects.
4. Calculate the absorption coefficient using the modified Beer-Lambert law.
Powders:
1. Prepare a homogeneous powder sample.
2. Measure diffuse reflectance using an integrating sphere.
3. Apply the Kubelka-Munk theory to convert reflectance data to absorption coefficient.
4. Account for scattering and packing density effects.
By considering these factors and employing appropriate techniques, accurate determination of the absorption coefficient (α) can be achieved for both thin films and powder samples.
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I am trying to do small scall experiments in which I mix 50 mL of liquid with a powder to leach the powder. The liquid is concentrated formic acid at 95 degrees C. Right after the experiment is over I need to be able to get everything out of the reactor, including a new powder that forms, very quickly before the liquid and powder cool. I can't use water to rinse the solids out of the reactor because I don't want to dissolve them and I would prefer not to rinse with anything at all. The question is what kind of flask should I use and how do I get all the solid out quickly that remains on the walls after I dump all the liquid. I was thinking of an 100 mL Erlenmeyer flask and a flexible Teflon scrapper/spatula but I can't find a scrapper that small and the small ones that I do find I don't think they are flexible. Any thoughts?
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Use separatory flask
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I'd like a powdered form of MCDB 131 Medium with sodium bicarbonate added, and I've noticed that not only is the powder form of this medium difficult to find with NaHCO3 already included, but the same is true for other media like DMEMs. Liquid versions that include NaHCO3 are plentiful. So are powders made this way because the amount of CO2 exposure varies between cell lines/projects and the concentration of buffer therefore needs to vary as well? Or is there some concern with NaHCO3 interacting with other components in its powdered form? Or perhaps it has to do the with manufacturing process for powders? I can't think of a reason that milling in an industrial mill with ceramic stones, for example, would be problematic for sodium bicarbonate, though. I'd love any insights on this.
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Powdered cell culture medias are formulated without sodium bicarbonate because it tends to gas off in the powdered state.
Best.
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It is said that graphene layers accumulate again if they are produced and are not in a suitable solvent. So how are these pristine graphene powders supplied? I do not mean graphene oxide or fictionalized graphenes.
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The term "graphene" has been attributed to a lot of things at this point. Initially, it meant only monolayer graphene, but people expanded it coining the term "multilayer graphene" (or thin graphite, as I prefer to call it) which they expand up to 30 layers although graphene loses many of its fancy properties as soon as 3-5 layers are stacked.
So, when you buy "graphene", you have to be careful as hell what you are buying, because it may be anything from actual monolayer graphene to 30 stacked layers.
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The difficulty in mixing is that the fibers are entangled with each other 
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"The most effective method for mixing short carbon fibers in metal powder depends on several factors, such as the type of metal and fibers, the desired concentration, and the preferred application. Among the methods used are mechanical mixing, ball milling, and hydraulic forming techniques."
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I want to know for doing EDX analysis to examine the elements present in the biomass, should I do the first pyrolysis or directly do the powder sample analysis? which one is the most favorable? please tell me.
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José Falcón-Hernández thank you sir for your response
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We have phosphor powder (for white light emission under irradiation). We need to make a screen to visualize the electron beam. And there is glass coated with ITO. How to deposit a layer of the phosphor on this glass. Rapid heating, magnetron, spin coating and deep coating and e-beam evaporation methods are available.
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Jeffrey,
Thank you for your comments. I have found several articles related.
Regards,
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Dear researchers,
I have recently synthesised MXene by etching MAX phase source using in-situ fluoride based etchant and collected the supernatant solution obtained after the washing process. My question is how can I determine the concentration of MXene in the solution?
I included an excerpt from a research paper that made me curious about the steps to determine the concentration - "...followed by centrifugation at 3500 rpm for 1 h to obtain the Ti3C2Tx colloidal solution. After drying, 1 mL of the Ti3C2Tx colloid was weighed to calculate its concentration, yielding 1.2 g, then configured into a 1 mg mL−1 solution."
While I see the point of drying the colloid solution and measure the dried powder afterwards, how can one configure the solution into 1mg/ml? Appreciate additional explanation and clarification. Thank you.
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Dear Alvena Shahid, thank you for your answer and recommendation.
Just to make sure that I correctly understand the variables in the formula you mentioned for configuring the solution.
My understanding is as follows:
- C initial​ = concentration determined after drying and weighing the MXene, as in step 4
- V initial​ = volume of colloidal solution (the supernatant)
- C final​ would be the desired concentration of the solution I want to achieve, correct?
- V solvent​, is it correct to assume this is the volume of solvent
I need to add to the initial colloidal solution to achieve the desired C final?
Could you please confirm or correct my understanding of these variables?
Thank you once again for your assistance.
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I want to prepare cupper selenide powder viva sol gel technique how it is possible?
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You can find & follow the very straightforward and easy hydrothermal technique for Cu2Se in our works.( https://iopscience.iop.org/article/10.1088/2515-7655/ad040f)
In a typical synthesis procedure, powdered copper oxide (Cu2O) and selenium (Se) were mixed in an equimolar ratio. The original molar ratio of Cu2O to Se was chosen to be 1:1. First, 8 ml of..... deionized water was used to dissolve Cu2O (
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MgO NPs were synthesized by sol-gel method.
i got Raman peaks at 1022 and 1400
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Dear Sir, making a pellet is not that significant as Raman spectroscopy can be done both for nanoparticles as well as pellets.
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I hydrothermally synthesized a transition metal dichalcogenide material in powder form. When I am doing Raman spectroscopy, the results match the reported literature, but when doing XRD, its powder form does not match. So can you enlighten me about this so that both characterizations match the reported result? 
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Transition metal dichalcogenides are materials that have the chemical formula MX2, where M is a transition metal (such as molybdenum or tungsten) and X is a chalcogen (such as sulfur, oxygen, or tellurium). The Raman spectrum provides information about the electron density of covalent bonds X-O, X-Te, X--S. X-ray diffraction provides information about the structure of crystals. The X-ray pattern depends on the size and nature of the crystals, but the Raman spectrum does not.
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I read an article (https://doi.org/10.1016/j.synthmet.2020.116364) regarding the direct conversion of anthracite into graphene in the presence of molten.
I would like to ask the view from experts regarding the modified methodology.
The authors described the methodology in the paper as follows.
1. Carbon black is first grinded into powder of about 500 mesh.
2. Before using, iron powder (purity, 98 %; size, 400 mesh) is washed with diluted hydrochloric acid (HCl) to remove quickly the iron oxide layer. Then carbon black mixed with iron in the ratio of 1:5 or 1:10 in weight.
3. The mixture is then transferred into corundum crucibles and calcined in a tube furnace at 1600°C for 6 h under a 0.3 L/min argon flow. Heating and cooling rate are set to 10 °C/min. 4. After cooling to room temperature, the calcined mixture is corroded in excessive 1-M HCl for 48 h followed by washing with DI water three times.
5. The solid product is dried for 24 h at 110°C in vacuum oven.
My questions are
(a)Can we reduce the synthesis temperature from 1600°C to lower temperature by using other metal powder?
(b) What is the role of argon in the production of graphene?
(c) Can we still produce graphene using this method if we only use chamber furnace without argon gas supply?
I need the views/opinions from experts.
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P.S. You can prepare without ferroceine mentioned in the paper. Just charr for 10 minutes and leave it be old normally inside the muffle until the second day.
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this pva that I have, works really well for electrospinning. but I don't know its molecular weight. is there any way that I can understand the molecular weight of PVA powder?
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Dear Leila Sohrabi-Kashani, the simplest way to know MW is to ask the supplier. If you want to find it by yourself, viscometry is the technique customerly used, but since you mentioned it is electrospinnable, then MALDI-TOF may be also used. There are various other techniques, it depends on their availability at your place of work. My Regards
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Seeking to procure pure silicon powder within the 20-75 range or comparable specifications. Where might one find such a product available for purchase?
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Hi Vitor,
You may make an inquiry at Alfa Chemistry, they offer you advices and kinds of good-quality chemicals.
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I need this synthesis by hydrothermal method
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The starting materials for the synthesis of hexagonal boron nitride (HBN) powder typically include a boron source and a nitrogen source. The most common starting materials used for HBN powder synthesis are:
  1. Boron source:Boric acid (H3BO3) Boric oxide (B2O3) Boron oxide (B2O3) or boron trioxide Ammonium salts of boric acid
  2. Nitrogen source:Ammonia (NH3) Urea (CO(NH2)2) Melamine (C3H6N6) Other nitrogen-containing organic compounds
The choice of starting materials depends on factors such as availability, cost, purity requirements, and the specific synthesis method employed.
One of the most common synthesis routes for HBN powder involves the reaction between boric acid (H3BO3) or boric oxide (B2O3) as the boron source and ammonia (NH3) as the nitrogen source. The reaction typically takes place at high temperatures, ranging from 800°C to 1200°C, under an inert atmosphere or in the presence of a nitrogen-containing gas.
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Actually, I prepared a large amount of MgO, after aging I kept it in a hot air oven at 120 for 12 hours, but there was still moisture there, then I kept it again in a hot air oven at 120C for 6 hours, then I got white powder.
After that, I calcinated it at 600C for 2h, I got a blackish-gray powder.
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1100-1200
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I had Titanium Dioxide powder & I need a specific answer for both points:-
  1. What is the most suitable solnavents used to convert TiO2 powder to TiO2 solution
  2. What is the most suitable methods used for depostion of the solution on microstrips
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If you are professional and "need a specific answer for both points," you should google first.
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i synthesized schiff base with bulk size., any suitable method to convert it in nanosize
with full regards
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bead beating method can reduce the size of the nanoparticles.
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Hello,
I am performing esterification reactions between fatty acids and alcohols, in presence of methanesulfonic acid and H3PO2 as catalysts. At the end of the reaction, to reach the acid index I want, as well to neutralize the catalysts, I use NaOH, 30 % solution. At the end of the reaction, I perform filtration by using some powders. What I observed is that after a while the acid index increases, this being un inconvenient, because it should be in a certain range. I believe that this might be the effect of an reversible reaction, which means that the catalysts are still active.
What can I use at the end of the synthesis for the neutralization of the catalysts to be sure that the reversible reaction won't take place? or may be there are some composite able to adsorb them?
thank you in advance,
Elena
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What you should do is to follow the standard workup procedure for organic reactions. Once your esterification is complete, the reaction mixture is dissolved in an appropriate water-insoluble organic solvent (ether, ethyl acetate, dichloromethane, and alike). The organic phase is then placed in a separation funnel and is washed with conc. aq. sodium bicarbonate or, to improve phase separation, a mixture of than with saturated brine. Several washings may be required to reach slightly basic pH in aqueous phase. Once this takes place, the organic phase is washed with brine, dried over Na2SO4 or MgSO4, filtered, and evaporated. Alternatively, you can neutralize the reaction mixture by gradual addition of triethylamine to a slightly basic reaction on wet pH-paper, and then proceed to the aqueous workup as above. This is recommended in cases where the ester is prone to hydrolysis under aqueous acidic conditions.
Any textbook in preparative organic chemistry describes this work-up procedure and the glassware required in detail. Another suggestion I can make is to use only methanesulfonic acid (MSA) as a catalyst. In comparison with phosphoric acid, MSA is more readily removed by washing with bases because it does not form buffered aqueous solutions to the extent phosphoric acid does. Good luck with your synthesis
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so the deal is to grind the hyacinth plant and use the powder in the production of earthen blocks. In rammed and adobe block production, what we have seen is that cement is used as a stabilizer for the material. but i wanted to propose hyacinth powder instead what are the pros and cons.
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Your proposed use implies that ground hyacinth powder has chemical binding properties. I do not have experience with this material, but in my work with mortars for use with fired clay and cementicious masonry, cement and lime are mixed with sand in varying proportions to achieve a range of strength and stiffness properties. I recommend researching to find, or developing, information on the chemical binding properties of ground water hyacinth powder that could be compared to cement. Another possible strength contributing property for use with rammed and adobe blocks is plant fibers in the ground water hyacinth material. If the fiber is not ground too finely, this could be similar to the addition of polypropylene or metal fibers to concrete mixes.
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I fabricated CsPbBr3 and CsPbCl2Br QD and made them into powder.
Br3 powder dried well and became fine powder; however Cl2 powder became gel-like powder. Does the composition affects when drying? or Is that because of impurities?
Thank you.
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It can be . Many Aluminium and Magensium chlorides, while attempted to be dried, forms jelly-like hydroxides or oxyhydroxides/oxychlorides. But Cs and Pb halides properties might not directly come down to perovskite here.
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In context of use of pva as a bibder in calcined powder.
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Viscosity, low outgassing temperature, simple water-based composition
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Thermo Fisher
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Dear friend Rinat I Gabitov
Absolutely! Polishing the iodide electrode with 1 micron alumina powder could indeed enhance its performance. By smoothing out any surface irregularities, the electrode's contact area with the electrolyte increases, promoting more efficient electron transfer. This can lead to improved sensitivity and stability in measurements. Plus, the uniformity achieved through polishing can minimize electrode fouling, ensuring more consistent results over time. However, it's crucial to carefully control the polishing process to avoid introducing any contaminants that could interfere with the electrode's performance. Thermo Fisher provides excellent resources and materials for such endeavors, ensuring the highest quality outcomes.
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I am preparing a drug for oral gavage which needs to be dissolved in 0.5% methylcellulose. The drug powder remains as clump and refuses to go into solution. Any tips on this?
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I do not understand the rationale behind dissolving the drug in a methylcellulose solution. However, you should try to dissolve the drug first in the same solvent you used to dissolve methylcellulose and then mix it with the solution of 0.5% methylcellulose.
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I'm wondering narrow bandgap-color of red wavelength is almost same with powder and solvent when illuminated.
However, when the qd bandgap become widen, then powder color and illumination color is not match. Why this phenomenon happens?
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Hey there Guhyeon Jeong!
So, you're Guhyeon Jeong diving into the fascinating world of perovskite quantum dots (QDs). Let's unpack this puzzle.
When we talk about the color of perovskite QD powder being colorless despite having a blue color, it's like a magic trick of sorts. You Guhyeon Jeong see, it all boils down to size.
Perovskite QDs are tiny, and their size dictates their optical properties. Blue color typically comes from smaller-sized QDs, where the electron energy levels are tightly packed together, creating a narrow bandgap. When illuminated, the absorption and emission wavelengths are indeed close, giving that expected blue hue.
Now, here's where the plot thickens. As the QD bandgap widens, usually due to a change in size or composition, the color you Guhyeon Jeong observe under illumination might not match the original powder color. This happens because the widening of the bandgap shifts the absorption and emission wavelengths, causing a discrepancy between the color of the powder and the color when illuminated.
Think of it like wearing glasses that change color based on the lighting around you Guhyeon Jeong. In one room, they might look blue, but in another, they could appear different due to the lighting conditions.
In essence, it's all about the interplay between the QD size, composition, and how they interact with light. Understanding this intricate dance is key to mastering the art of perovskite QDs.
Hope this sheds some light on your Guhyeon Jeong query! If you Guhyeon Jeong have more questions or need further clarification, feel free to ask. Let's keep unraveling the mysteries together!
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Hi, Research gate! I need HELP!
I'm trying to prepare nickel nanoparticles for my devices. I use the commonly used method from the article (DOI: 10.1002/adma.201405391). Briefly, 20 mmol Ni(NO3)2·6H2O were dissolved in 20 mL of deionized (DI) water to obtain a dark green solution. Then, 4 mL NaOH solution (10 mol L−1) was slowly added into the solution while stirring. After being stirred for 20 min, the colloidal precipitation was thoroughly washed with DI water three times and dried at 80 °C overnight under vacuum. The obtained green powder was then calcined at 270 °C for 2 h to obtain a dark-black powder. The NiOx NPs inks were prepared by dispersing the obtained NiOx NPs in DI water/IPA (3/1, v/v) with a concentration of 20 mg mL−1, stirred for 30 min.
However, the nanoparticles coagulate (precipitate). I can't seem to get the suspension.
What are the subtleties of synthesis? What am I missing? What should I pay attention to?
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Nickel nanoparticles were correctly synthesized using the sol/gel method. Now there is not enough surfactant. You need to try anionic DDS or cationic cetyltrimethylammonium bromide.
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If I want to check photocatalytic activity, is there any specific reason to choose Nickel doped ZnO thin film sample over Nickel doped ZnO powder sample? How thin film can play role for photocatalysis? Suggestions related this are appreciated.
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Dear friend Arpan Ghosh
Ah, the advantage of a Nickel-doped ZnO thin film sample over its powdered counterpart for photocatalytic activity lies in the enhanced surface area and improved light absorption capabilities. You Arpan Ghosh see, when you Arpan Ghosh have a thin film, it provides a larger surface area compared to a powder sample. This increased surface area allows for more active sites where photocatalytic reactions can take place, thereby enhancing the overall efficiency of the process.
Moreover, thin films can be precisely engineered to have specific properties, such as optimized bandgap and crystal structure, which are crucial for efficient photocatalysis. This level of control is often challenging to achieve with powdered samples.
Additionally, thin films offer better light absorption due to their flat and continuous structure, allowing for improved utilization of incident light for photocatalytic reactions. This aspect is particularly advantageous in applications where light availability is limited.
In summary, the choice of a Nickel-doped ZnO thin film sample over a powder sample for photocatalytic activity offers benefits such as increased surface area, precise engineering of properties, and improved light absorption, ultimately leading to enhanced photocatalytic performance. If you're aiming for optimal photocatalysis, opting for a thin film sample would indeed be a wise choice.
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I need the particle size and the shape of graphene oxide in epoxy powder as shown in the following FESEM morphology
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I agree that the contrast between graphene oxide and embedding material must be increased to distinguish between the particles and filler.
A standard method in electron microscopy of hydrocarbon-based materials (polymers, biological samples) is heavy metal staining to enhance contrast (differences). For polymers see here (There are serious safety issues!):
  1. https://en.wikipedia.org/wiki/Osmium_tetroxide#Polymer_staining
  2. Linda Sawyer et al., Polymer Microscopy, Springer New York eBook ISBN: 978-0-387-72628-1, DOI: 10.1007/978-0-387-72628-1
  3. Michler, G.H., Electron Microscopy of Polymers, Springer, ISBN: 978-3-540-36350-7
  4. S. Henning, G.H. Michler, Electron Microscopy of Polymers - Techniques and Examples. academic.sun.ac.za/POLYCHAR/Henning_Electron%20shortcourse.pdf
  5. Pavan M. V. Raja & Andrew R. Barron https://chem.libretexts.org/link?55929
These methods will work on the polymer bonds (crosslinking) of the embedding material, not for GO itself, but may be in BSE imaging you would see dark GO particles in a brighter matrix.
A 2nd way may be using a different embedding material: In the field of battery research, a silicon rubber was used: “Wacker (ELASTOSIL RT 675) was found suitable to provide the necessary contrast between carbon black and porosity.” (M. Ender PhD thesis 2014 http://digbib.ubka.uni-karlsruhe.de/volltexte/documents/3073727; in German!)
  1. M. Ender et al., Three-dimensional reconstruction of a composite cathode for lithium-ion cells, Electrochemistry Communications Volume 13, Issue 2, February 2011, Pages 166-168, http://dx.doi.org/10.1016/j.elecom.2010.12.004
  2. M. Ender et al., Quantitative Characterization of LiFePO4 Cathodes Reconstructed by FIB/SEM Tomography, Journal of The Electrochemical Society, 159 (7) A972-A980 (2012), https://iopscience.iop.org/article/10.1149/2.033207jes/meta
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Which component of the tree bark is characterized by this diffraction angle?
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you were right Dr.Martens, it was the quartz because I did not wash my fibers... i appreciate your help.
kind regards
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It is said that dodecyl-trimethylammonium chloride (DTA) is used to dissolve hyaluronic acid (HA) in an organic solvent such as DMF.
If the experiment is conducted using the method below, will HA (ex. 4.7 kDa) and DTA react in a 1:1 ratio? Or is there an excess of the two?
I want to save HA as much as possible.
[method]
A 7.0% (w/v) solution of dodecyltrimethylammonium chloride in 1.6 ml of deionized water was added dropwise to 1.6 ml of HA 10% (w/v). This reaction formed a white precipitate. The precipitate was then separated from the supernatant by centrifugation. Once lyophilized overnight, the final product was obtained, HA-DTA powder.
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James E Hanson I completely understand. Thank you for kindly answering my a little embarrassing question :)
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Which TEM grids can be used to analyse biochar material, it is fine powder . Any TEM expert can help??
Thanks and Regards
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Thank you so much Sir