Science topic

Acids - Science topic

Acids are chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. (Grant & Hackh's Chemical Dictionary, 5th ed)
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How is polylactic acid used in medicine?
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Used in tissue engineering or regenerative medicine, cardiovascular implants, dental niches, drug carriers, orthopedic interventions, cancer therapy, skin and tendon healing, and for medical tools equipment
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I am synthesizing choline geranate, an ionic liquid.
Before synthesis, I need to recrystallize geranic acid (85%), but I am having difficulty understanding the recrystallization method.
According to the research paper, recrystallization should be performed at -80°C.
To achieve this, I set up a water bath with acetone and dry ice to maintain -80°C and prepared a saturated solution of geranic acid in acetone at a 7:3 ratio. This allowed me to observe a solid precipitate forming through recrystallization.
However, I am unsure how to remove the acetone and isomers in this process. When I tried using filter paper for filtration, the geranic acid quickly dissolved.
Since this is my first time conducting this experiment, I would appreciate any advice on how to proceed with this step.
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First you can generate data of Metastable Zone Width (MSZW) of crystallization and estimate the cooling rate.
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Dear RG community,
I am looking to use magnetic colloids which are to be further dispersed in a polymer. To avoid agglomeration, I want to functionalize them using Oelic acid. I would appreciate if someone can point towards the exact procedure or a correct way of doing so. Also what purity grade oelic acid one needs to use (technical, culture, analytical etc.)
Thank you in advance
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The functionalization of a solid particle relies basically on the ability of the surface of the particle and the chemical you are aiming to functionalize with, to react together, with the aim of bonding, in your case, the oleic acid to the colloid. The way of doing it will depend specifically on that basically: on the chemistry that will be involved to link the acid to the surface of the particle. Since the oleic acid is exactly that, an acid, a way would be to explore a little bit the chemistry of the acid groups (how do they react, what other groups are needed, etc.). Also, knowing a bit more about the surface chemical groups of your particles would also be beneficial.
Hope it helps!
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Bonjour Mme Lemosquet,
Je suis salarié dans l'entreprise INNOVAL et en charge du support technique RUMINAL auprès des conseillers d'élevage.
J'ai des difficultés à comprendre le fonctionnement de RUMINAL concernant l'évaluation des apports en acides aminés digestibles et à savoir comment manipuler les données "aliments" et les indicateurs fournis par le logiciel.
Je souhaiterais avoir des informations de la part de la ou des personnes responsables du mode de calcul.
Pouvez-vous me dire qui est le.la référent.e INRAE sur ce sujet ? Mon seul contact RUMINAL est Pierre Nozière. Dois-je le contacter ou une autre personne (vous?) peut m'aider ?
Cordialement,
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Bonjour,
Merci beaucoup pour votre réponse rapide.
J'ai réussi à joindre Sophie Lemosquet qui va me répondre prochainement.
Cordialement,
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How are ester bonds hydrolyzed in a polylactic acid molecule?
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The hydrolysis of ester bond in PLA backbone chains created new end group, carboxyl and hydroxyl end group. Poly (lactic acid) (PLA) is well known for their biodegradability and bioresorbable properties and these
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Price? environment protection biodegradable?
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Polylactic acid (PLA) is 100% biodegradable and compostable, breaking down into non-toxic byproducts, making it environmentally friendly. Additionally, its production has a lower carbon footprint compared to traditional plastics, promoting sustainability and safety in applications like food packaging and medical uses.
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What are the specific steps for the preparation of polylactic acid by the two-step method?
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Nowadays, the most often utilized procedure is a two-step process that involves lactic acid oligomerization and depolymerization to generate lactide. To generate PLA, however, ring polymerization needs high-purity lactide, which can only be produced with high temperature, vacuum, and energy input during lactide manufacture.
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What role do terminal carboxyl groups play in the degradation of polylactic acid?
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Polylactic acid (PLA) is a biodegradable and bioactive thermoplastic aliphatic polyester derived from renewable resources, typically corn starch or sugarcane. The degradation of PLA occurs through a combination of hydrolysis and oxidation, and the terminal carboxyl groups play a significant role in this process. Here’s how:
  1. Catalytic Effect: The terminal carboxyl groups in PLA can act as catalysts for the polymer’s hydrolytic degradation. The carboxyl group can protonate water molecules, making them more reactive and thereby facilitating the attack on the ester bonds within the polymer chain.
  2. Chain Scission: The carboxyl groups can also directly participate in chain scission reactions. The free carboxyl group can react with the ester linkage in the polymer backbone, leading to the formation of shorter polymer chains.
  3. Lower Activation Energy: The presence of carboxyl groups can lower the activation energy required for the hydrolysis reaction to occur. This makes the degradation process more facile and faster.
  4. pH Sensitivity: The degradation rate of PLA can be influenced by the pH of the environment. Carboxyl groups can protonate or deprotonate depending on the pH, which affects their reactivity and the rate of degradation. In acidic conditions, the carboxyl groups are protonated and may be less reactive, while in basic conditions, they can be deprotonated and more readily participate in degradation reactions.
  5. Water Absorption: Carboxyl groups can enhance the water absorption of PLA, which is a critical step in the hydrolysis process. Water molecules can penetrate the polymer matrix more easily due to the polar nature of the carboxyl groups, leading to increased degradation.
  6. Microbial Degradation: Terminal carboxyl groups can also play a role in the microbial degradation of PLA. Certain enzymes produced by microorganisms can recognize and bind to the carboxyl groups, facilitating the degradation of the polymer by breaking down the ester bonds.
  7. Crosslinking: In some cases, carboxyl groups can participate in crosslinking reactions, which can initially slow down the degradation process by creating a more robust polymer network. However, once the crosslinks are broken, the degradation process can accelerate.
In summary, the terminal carboxyl groups in PLA are important for initiating and accelerating the degradation process by acting as catalysts, lowering the activation energy for hydrolysis, and influencing the polymer’s interaction with water and microbial enzymes. The degradation rate and mechanism can be significantly affected by the presence and reactivity of these functional groups.
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Is it possible to determine total sulphur in plant material from microwave acid digestion with nitric acid?
Thank you.
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Matthew is correct that there may be some S loss as volatiles and he has good experience with the ICP measurement of S in the digests.
If ICP is not able to be used there are other methods that work reasonably well but are more labour intensive
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What are the characteristics of the method for preparing high molecular weight polylactic acid by reaction extrusion?
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Reactive extrusion for preparing high molecular weight polylactic acid continuously enhances material properties through controlled temperature, functionalization, and chain extension. This method offers environmental benefits and improves mechanical strength and thermal stability.
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For failure analysis, sometimes parts received contains fully rusted fracture surface and surrounding areas. Is there an acid solution out there for soaking the parts or spraying solution to the corroded area to remove the corrosion products and obtain a clean surface for analysis?
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In our lab we use commercial products based on orthophosphoric acid. However, it should be remembered that after this a protective oxide film is created on the surface. If you need to examine the surface structure, this can be a problem.Recently I tried using a cheaper option - citric acid. It takes more time. However, there is an effect.
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We analyzed WSC to used method of phenol-sulfuric acid by spectrophotometer, and we calculated calibration curve. what do I need do next step? I don't know what I need do after this calculation. please help me
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A calibration curve, or standard curve is a graph of the signal (such as absorbance) on the y-axis versus the concentration of the analyte on the x-axis.
To use the curve to measure the concentration of the analyte in a sample of unknown analyte concentration, the same measurement is made on the sample as was made to produce the calibration curve. Then, read horizontally across from the y-axis absorbance measurement to the curve, and vertically down to the x-axis to read the analyte concentration.
If the calibration curve is a straight line, you can use math instead. Use linear regression to obtain the equation Y= MX+B of the calibration curve. Then, to obtain the analyte concentration of the sample use the equation X=(Y-B)/M.
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I am working on extracting tartaric acid from archaeological samples. So far, I’ve tried using MeOH/DCM and BF3/Butanol/Cyclohexane, but was not successful for real samples. I was able to get tartaric acid peak in GC-MS for fresh wine. Does anyone have suggestions on how to improve the extraction efficiency or alternative methods that might work better?
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To enhance the extraction and detection of tartaric acid from archaeological samples, several adjustments to your methodology and alternative approaches may increase efficiency. Given the degraded and complex nature of archaeological samples, standard solvent extraction methods that work for fresh samples (such as MeOH/DCM) may not yield sufficient results due to interference from decomposition products and environmental contaminants.
One possible improvement could be in modifying your solvent system. While MeOH/DCM is often used, alternative solvents such as acetonitrile, which is known to have a better affinity for organic acids, could offer improved extraction results, especially for trace acids like tartaric acid. Additionally, using formic acid as a solvent modifier might enhance the solubility of organic acids, further aiding in their recovery from archaeological matrices (Salvador et al., 2010).
Solid-phase extraction (SPE) is another method worth considering, as it is frequently used to concentrate and purify target compounds from complex matrices, such as those encountered in archaeological contexts. C18 SPE cartridges or ion-exchange resins could be particularly effective for isolating tartaric acid and other organic acids from environmental degradation products (Martins et al., 2008).
The derivatization process before GC-MS analysis is crucial for detecting organic acids like tartaric acid. While BF3/Butanol derivatization is commonly used, you might consider using trimethylsilylation (TMS) for your GC-MS work. TMS derivatization has been shown to increase the sensitivity of GC-MS for detecting trace acids in complex samples, and may improve tartaric acid detection in your archaeological samples (González et al., 2004).
If GC-MS is still not providing sufficient results, high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) or liquid chromatography-mass spectrometry (LC-MS) should be explored. These techniques are more sensitive and specific for detecting organic acids and have been successfully applied to detecting tartaric acid and other compounds in degraded samples (Kornblum et al., 2013). This could provide an advantage when working with the lower concentrations of tartaric acid typically present in archaeological material.
Furthermore, it is possible that the tartaric acid in your samples is tightly bound within complex residues, making it difficult to extract using traditional methods. In such cases, thermal desorption, followed by trapping and analysis, may offer a method to release and quantify tartaric acid without requiring solvent extraction (Cappellini et al., 2012).
In conclusion, you should consider adjusting your solvent system, employing SPE, modifying the derivatization technique, or even exploring HPLC-MS or LC-MS to improve the extraction and detection of tartaric acid from archaeological samples. These techniques have proven effective in similar complex matrices and may provide the sensitivity required for such trace analyses.
References:
Salvador, M. et al. (2010). Improved Extraction Methods for Organic Acids from Complex Matrices. Journal of Chromatography A.
Martins, A. et al. (2008). Solid Phase Extraction in Archaeological Residue Analysis. Analytical Chemistry.
González, C. et al. (2004). Improved Sensitivity in Organic Acid Analysis by GC-MS using Trimethylsilylation. Analytical Biochemistry.
Kornblum, R. et al. (2013). Applications of LC-MS in Organic Acid Identification in Archaeological Samples. Journal of Archaeological Science.
Cappellini, E. et al. (2012). Thermal Desorption in Archaeological Residue Analysis. Science.
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I recently performed a gas chromatography-mass spectrometry (GC-MS) analysis on a propolis sample and identified allocholic acid among its constituents. Considering that allocholic acid is a secondary bile acid primarily associated with mammals, I was intrigued by its detection in a product sourced from bees. Is the occurrence of allocholic acid in propolis a common phenomenon, or might this finding be influenced by specific botanical sources or distinct regional variations in propolis composition? Additionally, could there be potential interactions with the bees' microbiome or enzymatic activities that might account for this observation? I would greatly appreciate any insights or references to similar reports.
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Allocholic acid is an organic acid, it can be found in many organic environments. As is known, bees prepare propolis from tree resin, which is a waste product of trees. And bile is synthesized in the liver, which is also an excretory organ.
With respect, Pashayan S.A.
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As I claimed in my adsorption mechanism they adsorbed into the pore of MIl-101(Cr). How can I do it?
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Using a dialysis membrane with well-known pore sizes can help you estimate the size or molecular weight of organic dyes.
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Hi scientists,
The color of my samples in Phenol-Sulfuric Acid method turns into a bluish-greenish color after I add the sulfuric acid (5:1) to the sample containing phenol 5% (1:1).
This have happened several times, can anyone help me?
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thanks for your consideration Dr Balamurugan Krishnamoorthy
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Problem: reaction mixture has a black tar like texture so that it is not forming layers while doing workup with DCM and water+sodium carbonate anhydrous.
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Does it dissolve in DCM? If not, use different solvent like ethyl acetate or toluene for workup. If yes, does it mix with sodium carbonate solution (hence not layers)? If yes, you need to polarise aqueous layer more, like with salt. If no, you mean you have no reaction with sodium carbonate solution? If your acid is weak, you might not see bubbles, but it doesn't mean it didn't work, or maybe you need more vigorous stirring. If it still doesn't work, try adding tertiary base like triethylamine and do a flash chromatography run in low polarity system with triethylamine. Then your picoline derivative will likely come off before ionic salt of acid present. Make sure to check on TLC first though.
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I have seen in literature people using buffers such as PBS with pH 7.4, and dilute it with acid or base to create lower pHs like 2, 3,4 or higher pHs , will it still be called a buffer once buffering capacity is lost?
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Different buffers at the same pH can result in different effects on the function of your experiment. This could be due to the chemical composition and/or the ionic strength and/or the counterion. A good practice would be to test different buffer substances at the same pH to see if such an effect is occurring.
It isn't really possible to use a single buffer component for a very broad range of pH. There are some buffer systems that can cover a wide pH range by combining multiple components with different pKas.
Bis-tris-propane is an organic buffer that has a broad useful pH range of 6 to 9.5 due to having 2 pKas. Phosphate has multiple pKas (2.1, 7.2, and 12.7), allowing it to be used over 3 different pH ranges, but there are gaps in coverage.
The suitable pH range for a buffer is within 1 pH unit of the pKa, preferably 0.5 unit.
Some useful information about individual buffers and some two-component buffers can be found here:
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How can I prepare 3,5-dinitrosalicylic acid (DNSA) reagent used in Alpha Amylase Inhibition Assay? Any reference paper is available?
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Miller, G.L. (1959) titled "Use of Dinitrosalicylic Acid Reagent for Determination of Reducing Sugar" in Analytical Chemistry, 31(3), 426-428.
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Hello everyone. I have been struggling a lot with my western blots. I am treating my cells with short chain fatty acids and then extracting my proteins using RIPA/protease inhibitor lysis buffer. after that I am qualifying my proteins using Lowry assay, I am trying my best to avoid bubbles and to get accurate results.
the proteins I am trying to detect are vimentin and beta catenin. Migration assays and real time PCRs as well as previous results strongly demonstrate that there will be down-regulation of these proteins in response to the treatment.
when it comes to western I am struggling with equal loading since actin bands are looking inconsistent (especially in the control I am getting thin bands and with other samples as well). and the westerns have not been giving the expected results. I have repeated the westerns many times and I am still struggling... Can someone please help and suggest if there might be anything wrong with the quantification, cell seeding (working on SKOV and PA-1) or loading (although I doubt since previous westerns have given really good results).
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You said "previous westerns have given really good results". What are the main differences between previous westerns and problematic ones?
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I use BG11 to cultivate PCC.6803, and bubble with 3%-4% CO2.
20mM Tris-Hcl(pH8.0) were used to buffering the culture pH.
But after clutivate 2 days, when I test the pH of the culture, the pH always be around 6.5, and it's always acidic.
I guess the reason is the bubbling CO2, to make the culture acidic.
So what can I do to maintain the pH around 7.5-8?
Any suggestion would be highly appreciated.
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Using pH feedback control to supply CO2; generally speaking, a supply rate of 4% is considered too high.
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Hello
What should be done to separate and identify organic acids in HPC when their RetTime is the same?Like oxalic acid with Propanoic Acid.or acids that have a very close RetTime.
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Oxalic acid and Propionic Acid are hydrophilic, so make sure your column is for hydrophilic compounds. I have BioBasic™ AX HPLC Columns. I hope it helps.
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Hi, I'm learning about methods to separate acids and organic matter and trying to establish an experiment integrating DD and AR. While I was doing my research few questions popped in my head:
1. On what scale can these respective technologies can be conducted? If I am to separate H2SO4 from H2SO4-Glucose Mix on which rate can I extract it? 10L/day, 100L/day 100m3/ day? The pump specifications may change due to this so I'm asking this question.
2. What are some common practices in the industry to handle strong acids of different concentrations? H2SO4 is strongly acidic, and the piping/tubing, and the machines responsible for diffusion dialysis and acid retardation should also be able to withstand strong acids right? PTFE and 904L steel comes to mind are there other materials available to withstand corrosion?
3. What are some common resins used for Acid retardation? Seems like there is a wide array of materials and different companies depending on the region.
Thank you so much for taking your time to read this questions and answering them :)
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Hello!
It's great to hear about your interest in separating acids and organic matter using Diffusion Dialysis (DD) and Acid Retardation (AR).
Let's address your questions one by one:
Scale of Technologies for Separation:Diffusion Dialysis (DD) and Acid Retardation (AR) can both be scaled to various extents depending on the application. For DD, the scale can range from laboratory setups of just a few liters per day to industrial applications that can handle hundreds or even thousands of cubic meters per day.
The scale primarily depends on the number and size of the diffusion membranes and the overall design of the system.Specifically for H2SO4 from a H2SO4-Glucose Mix, it's feasible to start at a laboratory scale (e.g., 10L/day) and scale up to industrial applications (100m³/day or more).
The pump and piping specifications will indeed need to be adjusted based on the scale to ensure adequate flow rates and pressure handling capabilities.
Handling Strong Acids in Industrial Settings:Materials Resistant to Strong Acids: You're correct in considering materials like PTFE (Polytetrafluoroethylene) and 904L stainless steel, as they offer excellent resistance to corrosion by strong acids, including sulfuric acid.
Other Materials: Other materials that can withstand strong acids include:Glass-lined steel is often used for reactors and storage tanks.Titanium and Hastelloy alloys are also known for their superior acid resistance and are used in components exposed to highly corrosive environments.PVC and CPVC can be used for piping in less intensive conditions, although they are generally less durable than metals like 904L stainless steel or alloys.
Gasket and Sealing Materials: It's also important to choose the right gasket and sealing materials such as Viton or other fluoropolymer-based compounds, which have good acid resistance.
Common Resins for Acid Retardation:Resins Used in Acid Retardation: The choice of resin largely depends on the specific application and the types of ions or molecules being separated.
Commonly used resins include:Strong base anion exchange resins: These are often used when dealing with strong acids as they can exchange their chloride or hydroxide ions for sulfate ions, thus retarding the acid.
Weak base anion exchange resins: These may be used when the complete removal of the acid is not necessary, or when dealing with weaker acids.
Specialty resins: Some applications might require resins tailored for specific ion preferences or those that can operate under particular temperature or pressure conditions.
Regional Availability: The availability and choice of specific brands or types of resins can vary by region, with companies like Dow Chemical, Lanxess, and Purolite being major global suppliers of ion-exchange resins.Your research sounds intriguing, and the specifics you've considered (like materials resistance and resin selection) are crucial for setting up a successful experiment.
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I'm exploring the development of a material that dissolves in basic pH environments but remains stable in acidic pH conditions. I'd like to start a discussion on the feasibility of this concept, potential materials that could fit these criteria, and the challenges we might face in achieving this balance. Any insights or suggestions?
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Developing a material that dissolves in basic pH while remaining stable in acidic conditions is feasible but challenging. Potential candidates include amphoteric compounds, pH-sensitive polymers, and organic salts. Key challenges involve ensuring stability across pH ranges, controlling dissolution rates, and addressing environmental and economic factors.
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We are preparing one solution of different organic acids, but our target ph is 4.5, but due to acid nature of solution its pH ranging below 1.2-1.5. We tried to balance the ph with KOH, NaOH but both are not suitable, its start precipitating. Is there any other alternate and plants safe chemicals are thare to balance it ..?
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Ammonia
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The Acid aging in paper samples
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@Natalia Podlesnaia Thanks for your help and interest
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Suppose edema or high urea than what to do
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I shall reply just measurements for Euric acid testing how increased ,decreased and again increased,which I tell now combination treatment of Homeopathy and allopathic medicine 💊.
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I am working with amolecule which only soluble in acid or bases.
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It is possible, In pharma also many API / intermediates isolated in acid or base.
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Penconazole
1. CGA 132465
2. CGA 190503
3. CGA 127841
Fluopyram
1. AE C656948-benzamide
2. AE C656948-pyridyl-acetic acid
3. AE C656948-carboxylic acid
I have searched on sigma aldrich as well as on dr. erhenstofer site but i did not find any results.
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Thank you sir Chen Jingwen
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"What is the best pH for the preparation of a Schiff base from guanine and salicylaldehyde?"
And what is the mechanism in acidic and basic medium?
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Formation of Schiff base works best at neutral pH.
Alkaline conditions may result in the conversion of guanine into xanthine by hydrolysis of the 2-amino group of guanine.
Acid conditions may slow down the formation of the Schiff Base by protonation of the 2-amino group which is the driving force of the Schiff base formation.
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What's your suggestion for converting a heavy organic alcohol to its corresponding acid (via oxidation or dehydrogenation)?
Your industrial experience is appreciated.
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Check if you can find a metal oxide catalyte for oxidation.
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and chloroformate. But it takes 10 days to compete the reaction. How can I shorten the time of the reaction?
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Be careful with competition between cyclization and step-growth polymerization
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I want to replicate the third step, but there seems to be no reaction in an alkaline environment. However, sodium hydroxide is used in the literature. Should I switch to an acidic environment
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Depending on what the protecting group and the R's are, that looks awfully sterically hindered. My guess is that the base is removing the proton, but the action of the carbanion is not getting to the aldehyde carbon.
I assume you have water around since you are trying sodium hydroxide, water in the solvent is going to hydrogen bond to all those oxygen, making the steric situation even worse.
I suspect acid catalysis might be similar. It would protonate all those oxygens and all the surrounding positive charge would not help the situation. It might help to get out of hydrogen-bonding solvent with a non-aqueous base, but getting around steric problems could still be difficult. Since I don't know your protecting groups, I cannot speak to that, but I would keep them as small as possible too.
Having the ortho oxygens cannot help as they will repulse the anion with their lone electrons.
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I have synthesized CaFeO3 three times using metal nitrates through sol-gel method but each time XRD analysis show that its peaks match with Ca2Fe2O5. Metal to acid ratio is 1:1.38. I've also tried adding ethylene glycol.
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by which acid can we replace sulfamic acid to eliminate nitrite in a soil extract to determine the nitrate content by the DEVARDA method
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Unless you have high nitrite concentrations, e.g., around fertiliser bands, or conversion of nitrite is inhibited, nitrite concentrations are typically negligible. In any event, nitrite is readily determined colorimetrically.
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i was preparing gelmA by already reported method. but im unabke to seperate side product methacrylic acid and unreacted methacrylic anhydride. we donot have dialysing membrane facility nor we have lyophilization technique. kindly tell there alternatives
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I have taken around 100 mg of sample for digestion and final volume was 50 ml. But the acid concentration was too high in the sample so I had to dilute it again. I have taken 1 ml from the 50 ml solution and diluted it again to 50 ml. What will be my final dilution factor?
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The formula to calculate the dilution factor for ICP-MS analysis is:
DF = Vf / Vs
Where:
DF is the dilution factor
Vf is the final volume after dilution
Vs is the initial sample volume or weight
For example, if 100 mg of sample is diluted to 50 mL, the dilution factor would be:
DF = 50 mL / 0.1 mL = 500
If that 50 mL solution is then further diluted by taking 1 mL and diluting it to 50 mL, the overall dilution factor would be:
DF = (50 mL / 1 mL) . (50 mL / 0.1 mL) = 50 * 500 = 25,000
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Hi all,
I'm working on some acid-mediated sol-gel syntheses to make metal oxides. I have a few formulations working using only acetic acid, and metal-alkoxide precursors. However for some formulations, I need a pH lower than acetic acid can achieve alone and I'm unsure what alternatives to look for
Using fluorinated analogs of acetic (trifluoroacetic) did successfully work to lower the pH of the sol-gel and form smaller clusters, but also formed metal-fluoride species in the final products
Using formic acid appeared to work, but caused precipitation later on (too polar).
So basically I'm looking for an organic or mostly-organic acid to mix into acetic acid, to lower the solution pH without forming metal salts as a byproduct. Any suggestions?
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Citric acid is a weak organic acid that can effectively alter the pH level of solutions without causing the precipitation issues associated with formic acid. It is commonly used in various applications, including dyeing and food preservation, and could serve as a suitable option to achieve the desired pH reduction in your formulations.
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Use of thioglycolic acid as a stabiliser during the synthesis of nanoparticles
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Zhao Zhang, To remove sulfur from the surface of nanoparticles, solvents such as ethanol, dimethyl sulfoxide (DMSO), and water can be used for washing, along with ultrasonication and centrifugation. However, it's important to note that thioglycolic acid used as a stabilizer during synthesis can introduce sulfur onto the nanoparticle surface.
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While the purpose of adding acid types into the PVA plasticizer when making gel electrolytes in supercapacitors is for conductivity, what are the other purposes? So why do we add acid? Why do we add specifically sulfuric and phosphoric acid? Or KOH is added, is there a review or article explaining their purpose? I would appreciate it if you could share what you know, if you have any. There are interpretations of the electrochemical results when different gels are used. But I would like an article or rewiev on why they are used. In other words, it's a bit like the history of gel electrolytes, etc...
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Hey there Di̇lek Vatansever! Great question. So, why do we add acids like sulfuric and phosphoric acid into gel electrolytes used in supercapacitors? Well, beyond just enhancing conductivity, these acids serve a few key purposes.
First off, they aid in the formation of a stable gel structure. This is crucial for maintaining the integrity of the electrolyte and preventing leakage or degradation over time.
Secondly, these acids can help optimize the pH level of the electrolyte, ensuring optimal performance of the supercapacitor. They create an environment conducive to efficient ion transport and charge storage.
Now, as for why sulfuric and phosphoric acids are specifically chosen, it comes down to their chemical properties and compatibility with the other components of the supercapacitor. These acids offer desirable conductivity and stability characteristics that make them ideal for this application.
Regarding KOH, it's often used in different types of electrolytes, particularly aqueous ones, due to its high conductivity and low cost. However, in the context of gel electrolytes for supercapacitors, its use might be less common compared to sulfuric and phosphoric acids.
As for a review or article discussing the purpose of these acids in gel electrolytes, I'd suggest looking into electrochemical journals or materials science publications. There should be plenty of research articles out there delving into the intricacies of gel electrolytes and their applications in supercapacitors.
If you Di̇lek Vatansever need more specific references or further insights, feel free to ask! Always happy to help out a fellow researcher.
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I am trying to detect organic acids on my waters LC, which is equipped with a W410 refractor index detector. I am using a Aminex HPX-87H Column which is supposed to work to separate organic acids. I’m not sure if I’m missing something in my method settings but I am not detecting anything at all. If anyone has any insight that would be greatly appreciated
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Both, HPX-87H column and RI detector should be suitable for separation and detection of organic acids. However, I don't know either, if something is missing in method as I don't know your method. If you could provide some more information like solvent composition, standard concentrations, maybe a chromatogram, that'd be helpful.
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I have synthesized GO using a modified Hummer's method as follows: 0.125 g of graphite fine powder and 0.125 g of sodium nitrate were mixed followed by the addition of 5.75 ml of concentrated sulphuric acid under constant stirring for 10 min (in an ice bath). After that, 0.775 g of potassium permanganate was added gradually to the mixture (in an ice bath) and stirred for 10 min - the mixture color turned to dark green. Then, the reaction mixture was transferred to a pre-heated oil bath and stirred at 35 °C for 1 h. The obtained mixture was diluted by the addition of 10 ml of DI water, then heated up to 90 °C for 30 min. Again 25 ml of DI water was added. Last, 1 ml H2O2 was added to terminate the reaction -the mixture turned to earthy yellow. I washed the product with distilled water and dried it at oven 60 °C for 24 h -the resulting product is a little bit sticky black solid.
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Why I got two peak for graphene oxide one at 11.2 degree and one at 12 degree
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I want to synthesis sodium polyacrylate 40% solution in water in order to use it as dispersing agent for CaCO3. i have acrylic acid, NaOH and potassium persulfate as initiator. any one can help me in the order of adding materials to the flask, reaction temperature, time and if it is possible to do this reaction at room temperature after initiators are turning into free radicals at 60°C?
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im looking for a chain transfer agent for that reaction in order to obtain a low viscose low molecular weight product. do you know any one?
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I would like to double hydrolysis of an agricultural residue using sulphuric acid. The problem lies in the preparation of solvent dilution. Thank you
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Mix 1 volume of 72% sulfuric acid with 23 volumes of water (resulting in a 24-fold dilution). This is a simplified version of the well-known formula V1N1=V2N2
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At our lab we are trying to develop new dyes for different applications, and we need information about the stomach acidity of Galleria mellonella model.
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My objective is to find the binding affinity of divalent metal ions with polyacrylic acid (PAA) by Isothermal Titration Calorimetry. In this experiment, I need to prepare 2mM of PAA. The 2mM should be in monomer concentration terms. So, How do I calculate how much mass of polyacrylic acid do I need to measure if the average molecular weight(Mw) of choosen polyacrylic acid is 12000. If someone knows, please tell me in detail with mass calculation strategies.
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The answer is perfect for beginners to learn about it Thank you so much for your nice reply.
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My objective is to find the binding affinity of divalent metal ions with polyacrylic acid (PAA) by Isothermal Titration Calorimetry. In this experiment, I need to prepare 2mM of PAA. The 2mM should be in monomer concentration terms. So, How do I calculate how much mass of polyacrylic acid do I need to measure if the average molecular weight(Mw) of choosen polyacrylic acid is 12000. If someone knows, please tell me in detail with mass calculation strategies.
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Dear Siyanand Kumar Chaudhary, find the average degree of polymerization by deviding 12000 by the mass of the repeating unit which is the same as that of the monomer. What you find is the number of COOH acid group per chain. If you know chain end groups, more accuracy will be brought to your calculation, since the MW weight you are using is not too high to neglect the mass of the chain end-groups. Once you determine the equivalent of COOH groups, then you can prepare any concentration. The one you are targetting is too low, you can reach it by dilution of a known small concentration. By the way, the binding energies or affinity of PAA to metal ions was studied extensively decades ago, good bibliographic research is to be done on PAA polyelectrolytes to avoid repeating what was already done. My Regards
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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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Hello, I am currently conducting my Bachelor on a organic synthesis. Here, I first form an acid chloride by the addition of thionyl chloride and Dimethylformamide (which together form the Vilsmeier-Haack reagent) to my starting product (4-hydroxyphenylacetic acid) at room temperature. After, I add Triethylamine (a proton scavenger) and a dimethylamine HCl salt, the latter of which should react with the acid chloride in a amidation reaction. However, upon addition of the DMA.HCl nothing seems to occur and a IR-spec analysis of the final product shows a molecule reminiscent of polyethylene terephthalate (PET). This finding makes me think that there might be a polymerization reaction going on in which the acid chloride reacts with the hydroxy group of 4-hydroxyphenylacetic acid. This would also be able to explain as to why the DMA.HCl would not react in the mixture as all the acid chlorides would have polymerized before the amidation could occur.
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Dear Tom,
Maybe you should protect the hydroxyl group before amidation? Otherwise, the starting material 4-hydroxyphenylacetic acid will undergo esterification with itself.
Or you can use EDCI/DMAP/Et3N to amidate them instead?
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Hello everyone, recently I am trying to synthesize a dipeptide with a Coumarin derivative of Tryptophan, and the problem is it doesn't contribute in reaction at all.
Tryptophan itself in the same condition participated in reaction but the coumarin derivative does not contribute.
I have tried different agents such as TBTU and DIC/HOBt with PH=8
I tried activating the acid with N-hydroxysuccinimide but it didn't help.
What other parameters I can try or change?
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1) Check if you are using necessary protecting steps. When you say that trp "under the same conditions" gives a precipitate, be aware that any a-amino acid will give a diketopiperazine:
{2 RCH(NH2)CO2H -> R2C4H4N2O2
This would be expected to give a ppt with most amino acids trp so the result with trp by itself tells you nothing about the other reaction partners.
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2) There are many coumarin derivatives. Please specify how the coumarin is linked to trp: for example it can be an ester with a coumarin [3-, 4-,5-,6-,7-, or 8-] hydroxy derivative, or else an N-linked carboxy derivative of caboxy-substitued can link to the amino group through an amide link.
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Hello, everybody.
I am looking to add a DNAse treatment step to my bacterial lysis (gram-negative) procedure for crude enzyme extraction because my lysate always ends up being too viscous. We only have Zymo Research DNAse I in the lab and its information sheet says not to "avoid phosphate buffer and calcium chelators". However, I am using a chemical lysis procedure using Promega Cell Culture Lysis Reagent (following their bacterial lysis protocol) since we do not have a sonicator available. According to their information sheet, CCLR has 25mM Tris-phosphate (pH 7.8) and 2mM 1,2-diaminocyclohexane-N,N,N´,N´-tetraacetic acid. Does anyone know if adding DNAse I to my lysate will still work?
I am not sure of the composition of Zymo's DNA digestion buffer, but I was thinking of supplementing divalent ions to the lysate to counter the 2mM chelating agent in the lysis buffer. However, I am not too sure how to circumvent the phosphate problem. I am not sure how phosphate affects DNAse activity exactly. On the other hand, Thermofisher has a protocol for removing DNA from protein extracts (extracted using lysis reagent in phosphate buffer) using DNAse I. Will the phosphate component of my buffer significantly affect the activity of the DNAse?
Any insight on this matter will be greatly appreciated. Tips on how to solve the viscosity problem altogether are also greatly appreciated.
Thanks
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The following are the conditions when DNase I activity can be affected.
1. DNase I activity is influenced by divalent ions. DNase I has 10 times greater activity in buffer containing both Mg2+ and Ca2+ than either metal alone. Calcium is required to maintain structure and activity of DNase I. Trace amounts of Ca2+ may be present at sufficient concentration for DNase I to be active, but using calcium-free buffers or removal of Ca2+ by adding EGTA can reduce DNase I activity to undetectable levels.
2. DNase I is inhibited by metal chelators, monovalent metal ions such as Na and K (i.e., ≥ 100mM NaCl), SDS even at concentrations below 0.1%, reducing agents and ionic strength above 50-100mM.
3. DNase I is inactivated by heating to 65°C for 10 minutes in the presence of EGTA or EDTA.
4. DNase I is sensitive to physical denaturation. So, mix gently by inverting tube. Do not vortex.
If one uses PBS as an example to be used as the buffer, then monovalent ions present in PBS like sodium and potassium ions will inhibit DNase I activity as they will occupy any of the potential binding sites.
The contents of (1X) PBS are as follows.
137mM NaCl,
2.7mM KCl,
10mM Na2HPO4, and
1.8mM KH2PO4
However, the inhibition of DNase I can be reversed by adding divalent ions. This effect is related to the ionic strength of the system as well as to the positive charge present on the protein. I have not come across anything about phosphate on DNase I activity.
I feel you should give it a try since you also mentioned about the Thermofisher protocol for removing DNA using DNase I from protein extracts (extracted using lysis reagent in phosphate buffer). But do supplement divalent ions to the lysate.
Best.
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I have synthesized a sensor, which has sulphonic acid grp (-SO3H) and Boronic acid as well in it. And has a Molar mass of around 899 and also has an amide bond in it.. I am using Reverse phase HPLC to purify using ACN and Water(0.1%) as mobile phase. As I separate the compounds of one peak, the next very day it is splitting into two peaks in the chromatogram. Is TFA creating a problem? I could not figure it out. Should I need to use a buffer as an additive instead of TFA? Which buffer and how much is good for use? Could you please suggest?
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Hello, better with anion suppression Ion chromatography with NaCO3 and NaHCO3 mix 0.25M in water.
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I'm using the vanillin-sulphuric acid method to cuantify saponins but the colour that I observe is yellow instead of red-purple.
The method I follow from the literature is:
- 1 ml of sample extract + 0.25 ml 8% (v/v) vanillin in methanol + 2.5 ml 72% H2SO4
- Incubate mixture in 70ºC water bath for 15 min and then in ice for 5 min.
- Read absorbance at 560 nm.
Any sugestion or solution for this problem?
Thanks!
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The method you follow is correct. However, the saponin concentration must be high, more than 300 ppm, for the colour to develop. At lower concentrations, it does look yellow.
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Hi,
I am getting elevated results in my starch analysis. It is about 2-3 % higher than usual. We have not changed anything. We are getting the same results over and over. I have checked the 0.309M HCL, and it is perfect. Does anyone know why it sometimes reads higher?
When we put it into a boiling shaking water bath, we agitate it constantly. I have even tried not agitating it and I get the same values.
I have made the acid up a few times and checked it and it is fine.
The water baths temp is correct.
We filter it using 5-8um filter paper as we have in the past.
Thank you.
Kind regards,
Rob
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Hi Peter and Joseph,
Thank you very much for the detailed replies and time you have both given me.
I have been doing the starch myself, and then I did it with another analyst (I thought I was doing something wrong and needed someone to point out an obvious error in what I was doing - unfortunalty the error wasn't found). The repeatability and reproducibilty percentages are high. We are running a pet food starch from FAPAS in each run as a QC and a potato flakes sample. The pure starch is a good idea to run as well it in place of one of the others.
However, the megazyme method might be the best option moving forward. We have used Megazyme before for starch damage so I am familiar with how they work.
I will order a kit in next week and give it a go.
To you both, thank you again. Your help and expertise are very much appreciated.
Kind regards,
Robert
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Does dissolving the scaffolds in acid work to quantify that using spectrophotometer? or should i wait till the whole of the curcumin is released in the suspension media (PBS or curcumin solvent- ethanol).
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Dear Pavithra Pattabiraman, try extraction. In the following paper it is mentioned how to do that. My Regards
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[(CH3)3NCH2CH2OH]+Cl- + CH3CHCOOH + HOC(CH2CO2H)2 -> ???
2-Hydroxy-N,N,N-trimethylethanaminium chloride + 2-hydroxypropanoic acid + 2-hydroxypropane-1,2,3-tricarboxylic acid -> ???
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The chemical equation you've provided represents the reaction between choline chloride [(CH₃)₃NCH₂CH₂OH]Cl⁻, acetic acid (CH₃CHCOOH), and citric acid (HOC(CH₂CO₂H)₂). Here's the balanced equation for the reaction:
[(CH₃)₃NCH₂CH₂OH]Cl⁻ + CH₃CHCOOH + HOC(CH₂CO₂H)₂ → [(CH₃)₃NCH₂CH₂OC(CH₂CO₂H)₂]Cl⁻ + H₂O + HCl
In this reaction, choline chloride reacts with acetic acid and citric acid to form a product in which the choline chloride molecule is esterified by one of the carboxylic acid groups of citric acid. The balanced equation indicates the formation of the ester [(CH₃)₃NCH₂CH₂OC(CH₂CO₂H)₂]Cl⁻, water (H₂O), and hydrochloric acid (HCl) as products.
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Hello,
I am generating brain organoids. Some media require vitamin B27 +A, but we currently have vitamin B27 minus A vitamin. How bad will it be if we use B27 minus A instead of B27 + vitamin A? We also have retinoic acid. Would it be appropriate if B27 minus A were added (and how much)?
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since B-27 Plus supplement promotes survival and maturation of primary neurons.
B-27 Supplement Minus is identical to B-27 Supplement except for the removal of antioxidant components.
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Hi, I have to prepare the YCFA culture broth and do a bacterial growth test with each of the bile acids, however I am unable to dissolve the acids (lithocholic and ursodeoxycholic), any suggestions on how I could dissolve them? Also, would these acids degrade if I autoclave them?
I would greatly appreciate your advice
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Hello, Bile acids is not so easy to dilute in water actually it forma suspension as in bile acids main fraction is C24 fatty acids. The solubility will increase if you use warm water. Better to use membrane filtration 0.22-0.45 nm than autoclave to avoid degradation og bile acids.
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Please provide information on where I can purchase a 150 kDa, 500 kDa, 1000 KDa and 5000 KDa molecular weight cutoff membrane? for separation of ferulic acid (194 mwt) form mixtue of sample. where almost other molecular wt cut of is ranginng form 100 - 150.
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ok! I will check thank you for your time.
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What are the differences between 50 mM glycine-hydrochloric acid buffer (pH 3) and 100 mM glycine-hydrochloric acid buffer (pH 3), especially regarding osmotic pressure? Why do they have the same pH value but different glycine concentrations.If I need to use it to wash cell , which concentration of glycine buffer is closer to isotonic, thereby ensuring cell survival?
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The difference in glycine concentration results in a difference in buffering capacity, the ability of the solution to resist a change in pH when acid or base is added. The higher concentration solution has greater buffering capacity. For glycine at acidic pH, the pKa of the buffering group (the carboxylate) is about 2.3, so the solution will resist a decrease in pH better than it will resist an increase.
The osmotic pressure is proportional to the concentration of molecules or ions. Isotonic saline has a concentration of 0.9 weight % of NaCl, which is 154 mM NaCl. NaCl is fully dissociated into ions in solution, and therefore 154 mM NaCl has an osmolarity of 308 mOsm, due to the presence of 154 mM each Na+ and Cl-.
The osmolarity calculation for the glycine-HCl pH 3 buffer is tricky. Simplistically, the osmolarity of glycine-HCl is 3 times the molarity, since it is composed of 3 species (glycine, H+ and Cl-). However, this isn't exactly true, since some of the H+ is consumed to form protonated glycine. At pH 3, about 18% of the glycine is protonated on the carboxylate group, so the osmolarity would be a bit less than 3 times the glycine HCl concentration. Another complication is that additional HCl may have been added to bring the pH down to 3, increasing the osmolarity by twice the concentration of HCl added.
Overall, I would expect the 100 mM solution to be closer to isotonic than the 50 mM solution. I'm assuming that the amount of HCl added to lower the pH to 3 was relatively small, since the pKa of the carboxylate group is about 2.3. If it's very important to know the osmolarity of the pH 3 glycine-HCl buffer, I'd suggest looking for an osmometer instrument.
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I would like to calculate the volume from certain concentration,
people used 100 µL of 2 g/L solution then add to 100 ml acidic solution. how much volume should be if I will use concentration of 40 mg/L which will be added to 25 ml solution? Please write the calculations in details. Thanks
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Rania Mobarak I suggest for you to use: ratio and proportion, direct and inverse proportionality to calculate your unknown quantity. Firstly, convert milligram units into gram units or vice-versa, then proceed with your math manipulation to find the unknown quantity, using simple algebraic math manipulation.
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I am facing a reproducibility issue. I am measuring the specific capacitance for my sample (carbide based). I am getting pseudocapacitive behavior in CV curves. The first time while measuring GCD i am getting around 100 F/g at 1 A/g current density, but when i try to repeat the same i am not getting the same value. Moreover the GCD curve is not triangular shape.
Electrolyte used is 1M Sulphuric acid
Mass loading is from 1.3 to 1.8 mg/cm2
Potential window is from -0.1 V to 0.4 V
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Alvena Shahid Thank you for your reply, will check it out
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I used TBAPF6 electrolyte for CV study but it generated anion of my compound. Please suggest me which electrolyte would be suitable for cyclic voltametric study of mild acidic organic compounds?
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TBAPF6/Dichlomethane has too low conductivity. It's advised to use at least 10% CH3CN in dichloromethane to run CV
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How much quantity of sulphuric acid is required for acid hydrolysis of chemically purified cellulose powder to produce crystalline nanocellulose?
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You are very welcome. Good luck with your research!
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PGA solvents are toxic and I need a better approach to create films with this polymer.
In advance, Thank you for you time and consideration.
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A novel melt-foaming strategy using supercritical carbon dioxide can prepare porous PGA scaffolds with controllable morphology and outstanding mechanical properties without toxic solvents. Bioabsorbable poly(glycolide-co-lactide) fibers show increased crystallinity, higher tensile strength, and reduced heat shrinkage after post-annealing, supporting cleavage-induced crystallization. Also, PGA crystals and fibers exhibit high elastic anisotropy due to their planar zigzag conformation, with a tensile chain modulus of 294 GPa and a longitudinal shear modulus of 6 GPa.
Therefore, In vitro hydrolytic degradation of poly(glycolic acid) reveals a two-stage degradation mechanism, with irradiation decreasing this mechanism and resulting in a monotonic degradation profile at 20 Mrads. It is also worth noting that the buffering in a phosphate-buffered physiological saline solution accelerates the degradation of poly(glycolic acid) structures, potentially due to the presence of Na2HPO4, which removes degradation products and accelerates tensile strength loss.
Please see this researches that might be useful:
· Novel fabricating process for porous polyglycolic acid scaffolds by melt-foaming using supercritical carbon dioxide, ACS Biomaterials Science & Engineering, 2017. DOI: 10.1021/acsbiomaterials.7b00692
Best regards,
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Respected Researchers
Kindly explain the below mentioned formula for the calculation of TAN. I am not able to understand 4 in this formula.
Thanks in advance
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It contains the concentration of the titrand and possible dilution factors. You need to look at the exact analytical procedure behind the formula.
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45ml of 55% w/v sulphuric acid was taken. To hydrolyze 1gram of bleached mango wood cellulose. On addition of this powder to the sulphuric acid at 45°C , the mixture turned dark black! Whereas other article suggest that nanocellulose suspension should have been whitish? Why is it so?
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Sulfuric acid solutions with high concentration usually carbonize organic compounds.
Can you share an article you follow?
My colleagues have had experience with selective hydrolyzation of amorphous part of cellulose and production of microcrystalline cellulose from different kind of sources.
But concentrations were 0,050-0,1% HCl or similar
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Preparation of EDTA-
Citric acid solution in water.
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They do not react chemically.
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I have come across a suggestion to use HF and HNO3 mixture. But exact ratio is not clarified. What should be the exact ratio of these two acids to smoothly pickle Ni sheets? Any impurity in form of oxides must be absent before electrodeposition.
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Hi Lucky,
Thought am not sure the reason in choosing these 2 strong acid to work in your processing for pre-cleaning of Nickel sheets.
*** Watching the environmental issue as HF is never an easy item to control.
Suggestion to verify the purity of your Ni-sheet.. Avoid trace impurities may lead you to undesired-finishing, such as micro-pitting.
You may select the best optional of formulating picking-acidic solution at best concentration for surface pre-clean, b4 even to start electroplating processing.
Good luck.
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Hello, I have nylon fabric dyed with Acid dye. I need to prove for part of my project, is it possible or not possible, the reaction between dye molecules absorbed in nylon fabric with water molecules when the fabric is immersed in water. I hope someone helps me to find the best answer to this question.
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Normally the acid dye attaches to the Nylon by electrostatic forces (negatively charged dye SO3- and the material is positively charged NH3+), so in water there will be no reaction with water because the chemical potential of the dye is weaker on the fiber than in water.
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Hello everyone,
I need to use a final concentration of 90ng/uL of BSU polymerase in a final volume of 50uL. The NEB BSU polymerase specification sheet indicates 5ng/uL as the stock concentration. How do I convert units/uL to ng/uL knowing that one unit is defined as the amount of enzyme that incorporates 10 nmol of dNTP into acid insoluble material in 30 minutes at 37°C.
I am not 100% sure but I know that:
Specific activity (units/ng) = 5 U/μl / 10 nmol
To convert nmol to ng, we need to know the molecular weight of dNTP. Assuming an average molecular weight of 330 g/mol for a single nucleotide, we can calculate the specific activity in units/ng as follows:
Specific activity (units/ng) = 5 U/μl / (10 nmol x 330 g/mol)
and... if this is correct... then what?
Thanks a lot :)
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I believe you meant to write that the stock concentration is 5 U/µL. You can't convert this to an enzyme concentration of 90 ng/µL unless you know the specific activity (e.g., in U/mg) of the stock solution. 90 ng/µL refers to the protein concentration, not the nucleotide concentration that is produced by the reaction.
The specific activity may be written on the label or in the product information sheet or certificate analysis for the particular lot of the product that you received. This information may be available on-line from NEB. Once you know the specific activity, the conversion is simple.
For example, suppose the specific activity is 1,000 U/mg.
You need 90 ng/µL = 90 x 10-6 mg/µL
90 x 10-6 mg/µL x 1,000 U/mg = 0.09 U/µL
Since the stock solution is 5 U/µL you must dilute by a factor of 5/0.09 = 55.6-fold into the reaction.
Or, you could do it this way, using the same example specific activity of 1000 U/mg:
(5 U/µL) / (1000 U/mg) = 0.005 mg/µL = 5 µg/µL = 5000 ng/µL
The required dilution factor is 5000/90 = 55.6
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1. Oleic acid
Oleic acid is classified in a long chain acid. Should we keep in the acid storage cabinet? or keep in the general storage cabinet? which one would like to recommend?
2. Triethylamine
Triethylamine is classified in both "flammable" and "base". So, should we keep in the flammable cabinet? or keep in the base storage cabinet? which one would like to recommend?
would you give me an answer with reference articles?
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Oleic acid is not considered much of a threat as an acid. I looked at several sites online and could not even find a pka for it. I did find pka for some saturated acids
in the bilayer and they are essentially neutral. So that would go in general storage.
Triethyl amine is a strong base as organic bases go. https://www.masterorganicchemistry.com/2017/04/18/basicity-of-amines-and-pkah/
It is not a strong base compared to KOH or NaOH. My opinion is that it is not a strong enough base to be stored with those. I would put it in the flammable liquids cabinet.
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What are the possible ways of rectifying a lack of fit test showing up as significant. Context: Optimization of lignocellulosic biomass acid hydrolysis (dilute acid) mediated by nanoparticles
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Which steps, materials, temperature or stirring contain this process? Is there any publish or book? I want to materials make up only sulphuric acid and pyrrole monomer. Because my materials are unsufficient.. Thank you for your attention.
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Alvena Shahid thank you for your clear answering.
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I intend to modify a media, to better access de potential of bacteria (Pseudomonas and Bacillus) to produce organic acids in solid medium.
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Italo Alves Freire I think you can find many answers in works on solid-state fermentation:
Chundakkadu Krishna (2005) Solid-State Fermentation Systems—An Overview, Critical Reviews in Biotechnology, 25:1-2, 1-30, DOI: 10.1080/07388550590925383
Michael Mattey (1992) The Production of Organic Acids, Critical Reviews in Biotechnology, 12:1-2, 87-132, DOI: 10.3109/07388559209069189
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Hi!
I have a bacterial strain that changes the pH of the broth making it acidic. I want to get a knock-out mutant that is unable to lower the pH.
Since I'm using transposon mutagenesis without finding the transformant I want, I was considering to analyse the annotated reference genome to find the genes involved.
Honestly, I don't know where to start from.
I mean: should I look into the methabolic pathway using Kegg database or there are better ways to dig into the genome? Shoul I look for genes involved in the production of acidic compunds? How?
Any advice is appreciated.
Thanks!
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Would buffering the media not also be a solution?