Science method

Crystallization - Science method

The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
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Is it a good idea to try to achieve binding of my protein to a ligand by soaking, even though the Kd of the interaction is in the mM range?
I have many drops with the crystallised apo-protein from the optimisation that form nice single crystals, unfortunately using the same conditions again but with the ligand for co-crystallisation I do not have crystals for all ligands.
Would it be a good idea to test soaking with the native crystals by putting them in the same solution + an excess of ligand (around 50mM)?
Do you have any suggestions?
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Pisapia Luca Would you happen to know if the binding of the ligand disrupts the crystal contacts? Also to what kind of solution is the ligand solubilized in?
Since you are not getting crystals while co-crystallizing, it could be that something in the solution is inhibiting nucleation, or the ligand is disturbing the crystals formation by interfering with the crystals contacts.
Talking about concentration, its all relative to the experiment and the soaking compound. 50mM is not "high", but I would recommend doing is multiple time point of soaking, starting from few minutes and going up from there (15, 30, 45, 120, etc). Observe how the crystals look in the soaking solution. If they become malformed, its either much of a shock for the crystals or the compound is disrupting the packing.
You can alternatively try less concentration for longer time.
For co-crystallization experiment, could you try to first add the ligand to the crystallization plate and let to dry. Then add your protein/precipitant ontop of the dried drop. This can sometimes help with co-crystallization. Although, my experience is with smaller molecules.
Another thing you could try is to do microseeding experiment with co-crystallization with the ligand. Take your best looking drop with crystals, and resuspend them to the precipitant solution before crushing them(either by vortexing or harsh pipetting). One drop for some 10-20µl of motherliquid. You can then make 1/10, 1/50 or so dilutions from this. Add the microseed solution to your co-crystallization drop. For example if you have a 300nl drop(protein+precipitant+ligand), you could add 20µl of the diluted microseed solution.
Hope you find any of this helpful.
Regards,
Mikko Hynönen
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I have purified protein using affinity and ion exchange, in both of the buffers i used ph of 7.9, while concentrating in buffer exchange, i changed the ph to 7.5 and concentrated upto 5.4 mg/ml and set up for crystallization. will the change in ph affect the crystallization process ? my protein ideal ph is 7.4
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It's not clear what your question is. Do you have any results for the other pH such that you expect a change in the lower pH? If not, there is no way to predict how the pH in your protein solution will affect the crystallization. Even more so without knowing the concentration of your buffer, since you usually mix the protein solution with the crystal screen buffers leading to a variable final pH over a wide range. Last not least, what does "ideal pH of 7.4" for your protein mean? Highest stability, best crystallization condition or do you mean the pI of your protein?
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Hello every one,
I have seen somewhere that there is a critical size for ceramic additive particles (specifically BG) for making composite with semicrystalline polymer (specifically PCL). Above that size, the polymer's crystallinity increases and below that size, the polymer's crystallinity decreases. Is there any reference describing or proving this phenomenon?
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Dear Majid Sohrabian, not only size that affect the crystallization kinetics, also shape and concentration (sometimes refered as saturation):
The fourth parameter include any imposed work/stress on the system: flow, mixing, pressure.
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I am trying to cocrystalize my protein with a sugar ligand, for this protein in particular I obtain only clusters, I tried to play around the pH( from 4,5 to 8,5) using the condition with clusters but nothing. I am wondering if I need to perform an SEC on my protein to get rid of some contaminants that can affect my crystallization. If you have any suggestion that can help me, I will be happy to try.
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I would call this showers, rather than clusters,
If you haven't already SEC your protein before setting up trays, i would do.
Also, you may need to optimise the condition you have further to move the crystals from showers to clusters.
But, as Annemarie Honegger has linked to you can try to break off pieces, loop those individually to shoot as single crystals.
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solution mediated transformation of calcium sulfate dihydarate to hemihydrate
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@all
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"I am trying to crystallize my protein, Pqsd, and have several attempted to , but I have not obtained crystals. use screen jcsb plus, PACT, SG screen, Structure screen etc.
Here are the conditions I am using:
  1. Washing Buffer: 300 mM NaCl, 25 mM Tris (pH 7.5)
  2. Dialysis Buffer: 150 mM NaCl, 20 mM Tris (pH 7.5), 1 mM EDTA, 1 mM DTT
I have purified the protein, but despite multiple trials, I am unable to obtain crystals.
Key Information:
  • Protein concentration: [7mg/ml to 10mg/ml]
  • Temperature: 20°C.
  • No crystals are forming, and I’ve tested multiple conditions.
Could you help troubleshoot what could be causing the lack of crystallization or suggest alternative approaches? Specifically, should I modify my buffer composition, or try other crystallization techniques or screening conditions?"
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Is this the protein you are referring to?
If so, there are three structures in the PDB: 3H76, 3H77, 3H78, and the associated publication
lists the following conditions:
"ultimately, a mixture containing 0.16 M MgCl2·8H2O, 0.08 M Tris HCl, 24% w/v Polyethylene Glycol 4000, and 20% v/v glycerol (pH 8.5) yielded the best results. Needle shaped (0.1x 0.2x 0.4 mm) crystals were typically obtained after ~2 days. Ligand bound structures were obtained by incubating PqsD or the Cys112Ala mutant with 7.5 mM ACoA at ambient temperature for 15 minutes prior to mixing with the crystallization solution. Optimized conditions differed slightly from that which yielded the best unliganded PqsD crystals and contained 21% PEG 3350, 0.2 M MgCl2·8H2O and 0.1 M Tris HCl (pH 8.5). Crystals reached a suitable size in ~2 days. Attempts to grow crystals in complex with malonyl-CoA or DHQ were not successful."
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RNA isolation from the plant leaf samples.
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You are near the saturation point with 4M stock solution of GT. Slightly warming up should get it into solution; or as the previous author suggested, just use a lower stock concentration and recalculate your dilution.
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There is no specific range i got from DSC analysis. I searched in many research papers but still didn't get any clue about possible defending reason for crystallization temperature ranges between 250 to 320°C.
It's urgent
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Dear @Özgün but i m discussing about only crystallization temperature....is that justified...with urea formaldehyde matrix which have glass transition temperature 150°c and fiber decomposition at 300°c by TGA results
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Technically, Cold crystallizaion and Heating crystallization is measured, seperately and have differnt value. Some materials found Tc(Heating crystallization) but not found Tcc(cold crystallizaiton) in DSC analysis
I would ask Which thermal behavior makes two values different?
As far as I know, the shift of Tcc peak to right means the enhanced crystallization rate.
Then, I would like to know if the shift of Tc to right means decreased crystallization rate or not.
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Cold crystallization refers to the process where a substance crystallizes upon cooling from a temperature where it was in an amorphous or supercooled state.
Heating crystallization involves dissolving a substance in a solvent at an elevated temperature and then allowing it to crystallize as the solution cools down or as the solvent evaporates.
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I am reaching out to inquire about water benchmark values for specific processes within the potash industry, namely carnallite decomposition, sylvinite washing, and vacuum-cooling crystallization. As part of my research, I am interested in obtaining water benchmark values expressed in cubic meters of water per ton of potash product. I would greatly appreciate any insights or data you could provide on this matter.
Additionally, I am seeking water benchmark values for the phosphate mining industry, specifically expressed in cubic meters of water per ton of rock phosphate product. If you have any information or resources related to water benchmarking in the phosphate mining sector, I would be grateful for your assistance.
Furthermore, I am interested in exploring water benchmarking software for the potash and phosphate mining industry. If you are aware of any software solutions or companies offering such tools, I would appreciate your recommendations or insights.
If you are unable to assist with my inquiries directly, I would be grateful if you could direct me to any relevant information sources, publications, or industry contacts where I may find the information I am seeking. Many thanks.
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It offers a robust solution for measuring water benchmarks and managing environmental data in the potash and phosphate mining industry
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My initial attempts to separate the diastereomers through crystallization were unsuccessful. Since diastereomers have different physical properties, I was thinking of making the different forms and screening with different solvents to at least to enrich one. Among the different forms one is making the hydrated form and go-ahead. Since my molecule is amorphous in nature, even XRPD didn’t differentiate between anhydrous and hydrous.
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The definitive technique would be TGA to distinguish anhydrous from hydrated, which will be supported by molecular vibrating spectroscopy such as Raman FTIR.
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I am working on a variety of DNA and RNA structures (generally quite short 20-40bp) and I have seen some worrying results around stability. I understand the nature of the solution will affect the structures ie ice crystallization, pH etc but I was just wondering what others have used and why? Obviously there's Glycerol, trehalose etc any off the shelf solutions others can recommend before I spend the money?
Thanks
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RNA can be subject to self hydrolysis by its reactive 2'-OH group on its ribose sugar moiety at basic pH > 7. The hydrolysis seems to be magnesium enhanced so inclusion of EDTA to 1 mM in 10 - 20 mM Tris buffer chelates away the magnesium. Some people recommend acidic buffers. I have never actually worked with RNA directly. You also have to watch out for RNAse which is a nasty contaminant enzyme that enzyme that can survive an autoclave.
DNA is pretty difficult to destroy. It can be destroyed by DNAse but fortunately DNase doesn't survive an autoclave. Scientists have extracted DNA from thousand year old mummies so DNA is quite stable under extreme conditions.
DNA can be stored at -20C and RNA probably should be stored at -80C. I don't think ice crystal formation is even an concern for RNA and DNA. The concern is enzymatic or pH or metal driven hydrolysis.
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I want to know about the fundamentals of dating magnetite, how magnetite can be used for geochronology, and the methods and instruments used for measuring the time of magnetite crystallisation, especially in sedimentary iron deposits like banded iron formations (BIFs).
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Hi Radhika
The following paper provides an overview of the principles and potential applications of magnetite U-Pb dating. Hope this helps
Best
Amal
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Hello,
I am trying to estimate the thermal expansion of a semi-crystallin polymer (PEEK) with different degrees of crystallization. I couldn't find any rescources on this topic. Did somebody also encounter this specific problem? I'm just trying to get some orientation on how the degree of crystallinity effects thermal expansion to model it with isotropic material data.
Kind regards!
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If you have access to Ansys's material modules, they have a homogenised version of the material properties which includes a thermal expansion coefficient, vary it by a little up or down to see how it matches pre-existing data or how it fits your model. The other option is to contact Dr Jorgen Bergstrom (https://www.researchgate.net/profile/Jorgen-Bergstrom) @JorgenBergstrom for advice.
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Hi everyone!
my protein crystals like as follow(picture1),aithough they can grow bigger,but seem not to be a single crystal, and without good three-dimensional forms. how should i optimize them? could anyone give me some advices?
thanks!
my crystallizton condition are as follow:
protein concentration :10mg/ml
drop ration: 1:1
temp: 4 ℃
crystallization buffer: 0.1M Tris-HCl,0.2M(NH4)2SO4、25%PEG 3350、1mM NiCl2
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also you can try aging, where the smal crystals dissolve and incorporate in the bigger ones. Your crystals look like to be precipitate on a very fast way. try do add the precipiting agent slower in the solution. and dont forget the suggestion from Adron to seed the solution
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Hey so far i know that usually to calculate the percentage crystallinity of a polymer sample the enthalpy of melting is compared to the one of a theoretical 100% crystalline sample of the same polymer. My melting peak is very broad and probalby influenced by other factors aswell, my crystallization-peak however has a very clear start and end point.
That is why i want to use the crystallization-peak instead of the melting peak. I also know that the delta H of crystallization and of melting of the same polymer sample is usually not the same.
My additional question is, is there some sort of relationship between those two? For example the crystallization peak is the melting peak times a material constant or something like that?
I feel like the values will not be that comparable if i dont use the melting peak for the calculation can someone help me out?
I put a screenshot of the heating cycle (red curve) from -70 to 220 degrees and the cooling cycle (blue curve) from 220 to -50. Both at 10K/min.
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Palanichamy Perumal That sounds very interisting, i would love to try that. Unfortunately i do not have access to a machine for ultrasonic transit time/velocity measurements. I only have a DSC available to perform my measurements.
Thank you anyway.
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I frequently observe that any ruthenium complex that is crystallized turns into an oily, sticky substance. Additionally, the surface of crystals frequently has some depositions. How can this be resolved?
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Hey there Sanchita Das! Now, that's an interesting issue you've got with those ruthenium complexes. You Sanchita Das know, the crystallization process can indeed be a bit tricky, and it seems like you're encountering some stickiness and deposits on the crystal surface.
First off, let me say, this isn't an uncommon problem, and it often boils down to the specific conditions during crystallization. One potential culprit could be impurities or solvent residues, which might be affecting the crystalline structure.
Now, here's my suggestion: try optimizing your crystallization conditions. Ensure your solvent is ultra-pure, and maybe experiment with different crystallization methods. Adjusting factors like temperature, concentration, and even the rate of solvent evaporation could make a significant difference.
Additionally, consider using a suitable anti-solvent or co-solvent to enhance crystallinity and reduce stickiness. It's all about finding that sweet spot in the experimental parameters.
But hey Sanchita Das, the world of chemistry can be a bit unpredictable, right? Sometimes it's a bit of trial and error. Let me know how these suggestions work out for you Sanchita Das, and we can brainstorm some more if needed!
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why poly lactic acid doesn't have crystallization point in DSC
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Dear friend Je MIN Jung
Poly lactic acid (PLA) is a biodegradable and bioactive thermoplastic made from renewable resources, such as corn starch or sugarcane. The absence of a clear crystallization peak for PLA in Differential Scanning Calorimetry (DSC) is an interesting aspect tied to its polymer structure and behavior.
PLA has both amorphous and crystalline regions in its structure. The absence of a distinct crystallization peak in DSC can be attributed to a few factors:
1. **Amorphous Nature**: PLA tends to have a significant amorphous phase. Amorphous regions lack long-range order, and therefore, they do not exhibit a sharp melting or crystallization peak in DSC.
2. **Rapid Crystallization**: PLA has a relatively fast crystallization rate. In DSC, this can sometimes appear as a broad, less-defined crystallization region rather than a distinct peak.
3. **Multiple Polymorphs**: PLA can exist in different crystalline forms or polymorphs, each with its own distinct melting temperature. This diversity in crystalline structures can result in a broader or more diffuse thermal transition.
4. **Chain Stereoregularity**: The stereoregularity of the polymer chains in PLA affects its crystalline properties. PLA can have both L-lactide and D-lactide units, and the arrangement of these units can influence the crystallization behavior.
5. **Processing Conditions**: The conditions under which PLA is processed, such as the cooling rate during fabrication, can impact its crystallinity and the appearance of peaks in DSC.
It's worth noting that while PLA might not exhibit a sharp crystallization peak in DSC, it does have a distinct glass transition temperature (Tg) and melting temperature (Tm) associated with its amorphous and crystalline phases, respectively.
In summary, PLA's behavior in DSC is complex and influenced by its amorphous nature, rapid crystallization, polymorphism, and processing conditions. The absence of a clear crystallization peak in DSC does not mean PLA doesn't crystallize; rather, it crystallizes in a way that may not be as easily distinguishable in this particular analytical technique.
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A first order approximation of nucleation and growth, Avrami equation can be generalized to higher and fractional dimensions with knowledge of volume and surface area of hyperspheres as well as Gamma function. Experimentally fitted fractional dimensions of Avrami equation is interpreted as predominant dimensionality of growth dimension (e.g. dimension 2.3 means mainly two-dimensional growth of crystals with somewhat inclination to three-dimensional growth), but can the same be interpreted as fractal dimension and hence an indicator of self-similarity scale for crystal growth? What is standard interpretation of avrami equation with dimensionality higher than three if experimentally found?(with explanation)
In this discussion, the dimensionality of growth of avrami equation is value of n-1 in
ln(-ln(1-Y))= ln K +n ln t
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So I've been sorting through a collection of old microscope slides once used for teaching. I came across 12 slides of cockroach mouthparts mounted in what I believe is Canadian balsam, but they've gone completely opaque. The slides look a bit sparkly, so maybe some kind of crystallisation has occurred, but under the microscope it looks like a mess of fibres. We have hundreds of slide mounted in Canada balsam but no others look like this. I have no other information about the slides but I know nothing new has been added to this collection in at least 10 years so they are likely much older. I'm more curious than anything, does anyone have any ideas what might have happened?
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Hello Sarah,
this might be a kind of fungus growing under the cover slide. This phenomenon is well known from old lens groups that have been cemented with canada balsam, and that looks similar.
Kind regards,
Klaus
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Have I taken my area correctly to find the enthalpy of fusion Hm , so here the percentage crystallinty be Hm/Hm0 or i should consider the peak before the melting peak also and use the Hm-Hc/hm0 formula . Is this an example of cold crystallisation ?
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The degree of crystallinity of a sample can be determined from its DSC heating curve by calculating the enthalpy of fusion (Hm) and comparing it to the enthalpy of fusion of a 100% crystalline sample (Hm0). The degree of crystallinity is then calculated using the following equation:
Degree of crystallinity (%) = Hm / Hm0 * 100%
The enthalpy of fusion is calculated by integrating the area under the melting peak on the DSC heating curve. In the heating curve you provided, the melting peak is the sharp peak at around 165°C. To calculate the enthalpy of fusion, you would need to integrate the area under this peak from the onset to the end of melting.
Is your area correct?
It is difficult to say for sure whether your area is correct without seeing the entire DSC heating curve. However, based on the image you provided, it appears that you have integrated the area under the melting peak correctly.
Should you consider the peak before the melting peak?
The peak before the melting peak is likely due to cold crystallization. Cold crystallization is a process where polymer chains that have not crystallized during cooling crystallize during heating. The enthalpy of cold crystallization is typically much smaller than the enthalpy of melting. Therefore, you can usually ignore the peak before the melting peak when calculating the degree of crystallinity.
Is this an example of cold crystallization?
Yes, the peak before the melting peak in your DSC heating curve is likely due to cold crystallization.
Overall, I think you are on the right track to calculate the degree of crystallinity of your sample. To get the most accurate results, you should integrate the area under the melting peak from the onset to the end of melting using a DSC data analysis software.
Good luck
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  • New PLA-based materials need to be developed to allow a good balance between environment-friendliness and product properties for engineering/durable applications.
  • The blending of bio-based, brittle, and mostly amorphous PLA with semi-crystalline PAs (bio-sourced (e.g., PA11), or not (PA12)) has been reported to lead to high-performance materials (toughness, ductility, increased HDT and better thermal resistance, others).
  • The low crystallinity of PLA is believed to strongly influence its final properties and to limit the applications of PLA-based products.
  • Why not, the use of PLA (NA/nucleating agent) with high crystallization ability, to tune up the properties of PLA/PA blends !?
  • Our paper aims to show the experimental pathways followed to produce novel PLA/PA blends using PLA(NA) characterized by improved crystallization kinetics (impressive degree of crystallinity). Moreover, it highlights with the possibility to tailor the morphology and properties of PLA/PA blends with special compatibilizers, such as epoxy styrene-acrylate oligomers.
Murariu, M.; Arzoumanian, T.; Paint, Y.; Murariu, O.; Raquez, J.-M. and Dubois, Ph.
Engineered polylactide (PLA)–polyamide (PA) blends for durable applications: 1. PLA with high crystallization ability to tune up the properties of PLA/PA12 blends, European Journal of Materials 2022, DOI: 10.1080/26889277.2022.2113986
The authors would like to share this contribution and have your opinion about the approach developed in this paper! Thank you.
(NB: Paper available open access, European Journal of Materials, Taylor & Francis Group https://www.tandfonline.com/doi/epdf/10.1080/26889277.2022.2113986?needAccess=true&role=button).
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Hello Marius, I though you was retired :)
I agree that PLA / PA are scientifically very interesting. We publish a few paper on these blends. For instance, we find that nanofibrillar microstructures are easily formed / controled) and that the compatibility could be tuned. I will also try to publish a paper on peculiar crystallization effects at PLA / PA interfaces. By the future, probably investigate their piezoelectric properties. Anyway, this subject is still alive. However, I guess that industrial application are more complicated by now...
Best regards,
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If a doped a material in a matrix. Its glass transition temperature and crystallization temperature decreases compared to the matrix but activation energy increases (Kissinger, Moynihan). Please give me the explanation for increased activation energy with decreased Tg and Tc.
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I personally have not much experience with crystallization studies, but i suggest studied by professor Vyazovkin, e.g, the most recent one
to start with. Besides, the general comment on kinetics is that mentioned methods (Kissinger, Moynihan) should be used only for preliminary assessment, the final kinetic models should rely on more advanced kinetic technoques (see the ICTAC Kinetic commitee recommendations)
Best,
NM
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Hi.
I am working on the Raman spectroscopy for cancer cell lines.
For that, we seed cancer cell on the CaF2 window , fix it and contains it in the PBS. We observe the cells without coverslip.
When we see the cell in the PBS, it was fine but after taking it out of the PBS and drying, it seems like the pictures below: some crystallizations and something black dots? on the cells
What I was thought is, it is the dried salt from the PBS but I'm not sure.
So my question is
1. What is the reason in the picture below happen.
2. What should I do if I want to avoid question 1. problem?
3. Is there anything special procedure needed for the cell sample without coverslip?
Thank you
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@Joshua Depiver
Thank you for your kind answers!!
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I have a DSC result run from -90oC to 100oC in a heat/cool/heat cycle.
Tg, crystallisation and melting peaks are observed in the heat run. However the cool run, the crystallisation peaks are not reflected. What is the course of this from the polymer?
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Is there a special reason why you would use 2K/min instead of the standard 10K/min? I suggest you to use higher heating/cooling rates (10K/min or even 20K/min), a sampel weight of 10mg, N2 atmossphere and an alumnium crucible. This will amplify the heatflux signal at the transition temperatures and shift them a bit (as described above).
If your material is like the one in this paper , you will decrease the nucleus density of your material substatially as you keep the material for quite a long time above Tm. This will reduce the cristallisation peak (the melting peak reversed), especially when cooling with such slow rates. So maybe stop at a lower temperature when heating (comapre with your heating results).
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Solvent System
crystallisation technique
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According to a post on **ResearchGate**, the best method to grow crystals for organic heterocyclic compounds is to first dissolve the compound in either ethyl acetate or acetonitrile or DMF by warming, allow it to cool in the freezer for 24 hours or more time. You will get the crystals (https://www.researchgate.net/post/Can_anyone_please_suggest_the_best_method_to_grow_the_crystals_for_organic_compounds).
Another method that works well is to dissolve 50-100 mg of each compound in small (5 mL) vials in the minimum amount of organic polar solvent (https://www.researchgate.net/post/Can_anyone_please_suggest_the_best_method_to_grow_the_crystals_for_organic_compounds).
The **Center for Xray Crystallography** suggests that evaporation is the most common methodology for crystal growth. This involves simply evaporating solvent from the solution of the compound until saturation is reached and crystals form. However, this method is not the best and often leads to ugly crystals since the crystals tend to grow on the surface of the vessel (https://xray.chem.ufl.edu/helpful-information/crystal-growing-tips/).
I hope this information helps you. Let me know if you have any other questions.
Source:
(2) Crystal Growing Tips - The Center for Xray Crystallography. https://xray.chem.ufl.edu/helpful-information/crystal-growing-tips/.
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Dear colleagues! Have you ever studied Zr52.5 Cu32.5 Al10 Fe5 ? Could you share your experience if you have? I am interested in its phases.
I am studying the crystallization of this alloy from an amorphous state when heated, I cannot decipher the XRD analysis.
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Thnx for your answer!
To evaluate crystallization, I annealed the amorphous film and sample after hpt at the temperature of the first crystallization peak on the dsc curve. It was possible to determine the phases separated in the film. However, after deformation, the pattern has changed and I cannot figure out which phase is crystallizing. In my databases, there is no such position of intensity peaks.
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Why does Nylon, like Polyamide 66, have higher crystallization temperature after processing? We have tested the DSC (cooling rate: 20℃/min) of the Neat Polyamide 66 chips (without additives), the DSC shows the crystallization temperature is 208℃, but after extrusion or injection molding, the DSC results of the extrudates or injection molding bars show the crystallization temperature up to 230℃. Is this because of the reduction of the molecular weight after processing? But we have test the relative viscosity before and after processing, and show no significant difference.
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Claude Le Gressus Thank you very much. There is one paper attached studied this phenomenon. I do not know the conclusion of this paper is correct or not. I will do some experiments to check out.
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Hi all, I set up the crystallization of protein-DNA complex for initial screen and found one crystal cluster appeared in a condition (0.1M HEPES pH7.0, 0.2CaCl2·2H2O, 45% MPD). Afterwards I added 10% glycerol and seed to optimize the crystal but it still turned out crystal clusters. How can I improve it into regular single crystals?
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I have abundoned that field research long ago and cannot help you much.
Prabal Dasgupta
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"I am conducting a study on PLA/PCL blends and need to determine the crystallization temperature of PCL using DSC data. Which cooling cycle data should I select to obtain this information, the first or second?"
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The crystallization temperature of polycaprolactone (PCL) is an important parameter for determining its physical properties and processing capabilities.
Obtaining this temperature requires a diligent approach to experimentation and data analysis. One method involves utilizing differential scanning calorimetry (DSC), where the sample is heated at a constant rate while simultaneously measuring the heat flow.
The crystallization temperature is then determined by observing the endothermic and exothermic peaks, which represent the melting and cooling processes respectively.
It is crucial to select appropriate heating rates and sample sizes, as well as calibrating equipment properly for accurate results. The obtained data can then be analyzed using various mathematical models, such as Hoffman-Lauritzen or Ozawa methods, to determine the degree of crystallinity and other mechanical properties of PCL. In conclusion, obtaining the crystallization temperature of PCL is a meticulous process that requires proper equipment and techniques to yield reliable results.
Hope you find what you ask about
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In many research articles, it has been observed that 50/100/500 mL of solvent is commonly used for synthesizing metal oxide nanoparticles. While the metal precursors are soluble in a lesser volume of solvent than the amount used, it remains unclear why more solvent volume is used than what is necessary to dissolve the metal precursors.
Are there any correlations between solvent volume and supersaturation, nucleation, crystal growth or Ostwald ripening in nanoparticle formation?
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To obtain metal oxide nanoparticles, the sol (metal hydroxide)-gel (metal oxide) method is used. First, a sol (metal hydroxide) is obtained. It dissolves much worse than its salt predecessors. To avoid overexpenditure of the reagent and undesirable side reactions, dilute solutions are taken. Focus on the value of the solubility product of the hydroxide.
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My compound is soluble in THF ,DCM and Toluene .I am doing small scale crystallization in 5 ml vial taking 10 -20 mg of solid compound in each vial. I have already tried THF, THF/Pentane, DCM, DCM/Pentane, Toluene, Toluene/ Pentane combinations. In case of Toluene, I am getting ppt. In case of THF and DCM, even after 2nd and 3rd pentane layering I am not getting anything, not even ppt. Now what could be the solution ?What are the things that I should try ? I will highly value each of your suggestions.
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If you have already tried several solvent combinations for your small-scale crystallization and have not been successful, there are a few additional things you can try.
Firstly, you can try adjusting the temperature during the crystallization process. Lowering the temperature can sometimes help induce crystallization. You can also try adding a small amount of seed crystal to the solution to encourage crystallization.
Secondly, you can try a two-solvent crystallization method. This involves dissolving the compound in a solvent that is a good solvent at a high temperature but a poor solvent at a lower temperature (such as THF) and then adding a second solvent that is a poor solvent for the compound at all temperatures (such as hexane or heptane). By slowly cooling the solution, the good solvent will gradually become less effective at dissolving the compound, which will start to precipitate out of the solution due to the presence of the poor solvent. You can then filter the crystals and wash them with the poor solvent to remove any remaining impurities.
Finally, you can try a different technique such as slow evaporation or anti-solvent precipitation. Slow evaporation involves allowing the solvent to slowly evaporate over time, which can sometimes induce crystallization. Anti-solvent precipitation involves adding a poor solvent to the solution to induce precipitation of the compound.
It is important to note that the best method for crystallization will depend on the specific compound and its properties, so it may require some experimentation to find the most effective approach. Additionally, it may be helpful to consult with colleagues or experts in the field for additional guidance and suggestions.
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Except adding a small amount of oxygen or increasing the pressure of the growth atmosphere, are there any other methods to inhibit the volatilization of Ga to maintain stable crystal growth conditions?
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We have grown GaSb bulk crystals by vertical directional solidification process (VDS-Process) in a vacuum sealed an ampoule. Check, whether it is suitable for your work, articles are on RG.
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The crystallization procedure has different stages like induction, transition, and crystal growth.
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Time zero?
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hi everyone
I have simulated crystal growth in population equations with constant growth rate by Fluent, my results are bad. In the log-normal number density diagram, the value at the peak is smaller than the standard and is created faster than the specified time. Can anyone help me?
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solving PBE in Fluent is a complex task, have you double checked the user-defined subroutine ( UDF) that describes the particle interactions, such as nucleation, growth, and coagulation.
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Solved
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Your question os too generic, and o Hope these information may help you
There are several característics of a cristal like size, crystallinity, shape etc. Sodium chloride normally is cubic. X Ray can be used to determine crystallinity. Particle size distribution can bê measured by sieving pra by laser diffraction. MEV is useful to identify physical aspects.
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Hi all!
Is anyone aware of a model protein that crystallizes, albeit slowly? (~3-6 weeks)
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Protein crystal growth affected by temperature, pH, protein solution stability, saturation, nucleation, impurities and so on. Decreasing the temperature during nucleation works to slow down the crystal growth. And one should try above mentioned parameters.
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I am looking to test activity of my crystallized protein so I am interested to know weather protein can be extracted from crystal state without damaging the viability of particular protein? and how it can be done?
Looking forward to receive helpful suggestions.
Thanks
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You can simply dissolve some of the crystals in a small volume of a suitable buffer for the activity measurement. You can measure the protein concentration of the solution, if needed to determine the specific activity.
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Hi all,
I am looking for references about measuring crystallisation and metling enthalpy of pure water with differential scanning calorimetry (DSC).
Although this seems to be quite a straightforward job, are there any challenges associated with it?
Moreover, how can the presence of ions/proteins/biological membrane fragments, dissolved in water, affect the enthalpy of those phase transitions?
With many thanks
Best
Filippo
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Yes exactly, and it is well explained in one of the attached files. It adds also that the induction of crystals formation for sure will not be the same as in the reference enthalpy you refered to, because of many factors. This may include the environmental conditions, the instrument used and its accuracy (expected high compared to old instruments), the specimen holder (nature and geometrical form), and possibly others, all contribute to the obtained values. However as a general view, the values are not so far from each other. Good Luck in your work
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I isolated a crystalline solid that appears to be a sugar. I need to purify it but I cannot recrystallize it because it is only soluble in water. When concentrating it, it always ends up becoming a molasses and never crystallizes. Its not sucrose or any other common monosaccharide.
How could I achieve recrystallization of this solid?
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Eduard Rusanov Thank you very much! I'll try to refrigerate the mixture and see if anything precipitates.
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self‐assembly in the crystalization process.
The origin and the first study in the field of self‐assembly
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Dear Mohammad,
I suggest to clearly define what you mean by "self-assembly".
The problem is that this term has been very often used in completely non-specific way, just to boost the importance of a paper or report. I call this buzz-wording. Imho this term should not be used for:
1) the assembly of ions in a crystal lattice
2) any simple bond formation of a coordinative or covalent bond
Personally, I find the term "self" misleading as in many cases, the researchers are driving the assembly clearly in just one way. Or there is only one way of aggregation of the ions or molecules.
I would use the term "selective assembly" if there are more than one possibility to form an aggregate or a crystal or a complex and one way is selective over the others.
If there is only one way how the particles (ions, ligands, molecules) can assemble, then there is no extra word like "self" needed, and we should call this specifically "coordination", "forming of H bond", "crystallisation" depending what forces finally keep the particles together.
Best
AXEL
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Here, this is the method :
"D-Fructose (2.16 g) is dissolved in water (4 ml) at room temperature. Boric acid (0.372 g) is then added to the thus prepared Solution, and upon its dissolving calcium carbonate (0.246 g) is added in Small portions. After carbon dioxide evolution has ceased, acetone (99%, p.a. quality; 20 ml) is added to the reaction mixture, whereupon a colorleSS oil Separates at the bottom of the reaction vessel. Two layers are separated using a separatory funnel, and the lower layer (crude boron complex) is treated again with acetone (20 MI). Upon standing at room tem perature for one hour, the mixture is triturated using a glass rod to induce crystallization, and the oil slowly Solidifies. This produces a white crystalline solid. "
I did exactly the same things written here but crystallization never occurs. Any idea ?
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Of course, grinding is necessary to cause/start the crystallization of the oil, because small glass particles can serve as a seed for the crystal formation process. It is likely that crystallization does not occur because, for example, the temperature in your laboratory is too high! try putting the vessel in a cool place, such as a refrigerator.
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Hi everyone, I'm trying to crystallize a truncated DNA-binding domain of a transcription factor (Nuclear Factor I X) but its DNA-binding affinity is not optimal, therefore the complex is not very stable and its crystallization is quite tricky. I was wondering if there is one or more compounds that are known to favour DNA-protein interaction in such a way to promote complex formation and to make it more stable.
If you need more informations to answer this question, please just ask. Thank you!
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It might help to include a divalent cation such as Mg2+ to neutralize the charge on the DNA backbone, if there is electrostatic repulsion. On the other hand, it might be better to minimize the ionic strength (salt concentration) as much as possible to favor ionic interactions.
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Hey guys. I'm working with speed vac at the moment. But I don't know if it's the best way to concentrate the sample. Another question is whether it is normal for the sample to become viscous when more concentrated. One more question: sometimes the sample becomes saturated with other components of the buffer when it reaches a certain concentration. Can I dissolve it with water to undo the precipitation? Is there quantitative or qualitative loss of protein when it occurs?
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Dear Laiana,
As far as I know, speed vac is optimal for nucleic acid concenetration. In our lab, to concentrate proteins either for crystallization or for other applications, we use Amicon Ultra centrifuge filters. They exist with different cut-off sizes, depending on the MW of your protein. You want to use a cut-off that is smaller than the MW of your protein of course.
Regarding the precipitation event, I don't think you will be able to recover the precipitate just dissolving it in water, since it got out of solution because of its insolubility in water. Eventually, when precipitation occurs, you have a quantitative loss of your protein for sure. Instead, I wouldn't say that you would have a qualitative loss, but consider the possibility that your protein precipitated because of some unfolding/musfolding event.
I hope this will help you, good luck!
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Two pieces filled (by inner CaCo3 crystallization) that look like: either two vertebrae or a calcite filling of karst veins. Can you give your opinion on these two forms of fossil or mineral?
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Thank you
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My DSC curve (Figure1) do not show a horizontal shape. It may be related to the calibration, even though we recently calibrated the instrument.
In any case, the software offers an option in the settings tab: DSC/DTA Horizontal on/off (Figure 2). Using this mode, the curve changes to what I would expect and what is reported in the literature (Figure 3). Does this setting affect my analysis (glass transition, ...)? Can I rely on this setting to perform my analysis?
The glass transition isn't clearly visible in my curve (Figure 1), but when I apply DSC horizontal mode, I can clearly see it (Figure 3).
If I can use this setting, how/where should I set the segment (Figure 4)??
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"... My DSC curve (Figure1) do not show a horizontal shape. It may be related to the calibration, even though we recently calibrated the instrument.
Is this (Fig. 1) the blank line???
You can take your measurements without using the settings tab: DSC/DTA Horizontal in off !! And then subtract the blank line from the curve.
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I am synthesizing coumarin-3-carboxylic acid but products are not pure. I have done crystallization to purify them , they are still impure .Besides GC and HPLC , what other techniques should I use for purification.
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Hello, i did H&E staining using cryosection.
However, there are so many holes in myofiber.
Here is my protocol.
No fixation for myofiber staining
1. Dissection - skeletal muscles
2. Embed into O.C.T using liquid nitrogen
3. After completely frozen, stored at -80c before using
4. Put it into -20c cryostats 20 mins before sectioning.
5. Cut to 10μm thickness
However, it is really hard to cut without getting holes, even though the blade is brand new.
Is the problem of water crystalization or freezing time?
Please help me.
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The holes seem to have formed due to ice crystals rupturing the tissue. If the experimental animal wasn't perfused with saline followed by PFA, I would recommend a post-fixation of the tissue.
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I am performing experiments with optical cryomicroscopy. My samples seem to get crystallized upon cooling at -110 degrees celsius. Also, I am able to see some crystal structures when I freeze a thin layer of the sample.
But when I passed the cross polarised light through the frozen droplet of the sample I am not able to see any image. As seen in previous articles if the sample is crystallized, I should be able to see a bright light with the structure of dendrite formation in the droplet by using the cross polarised light.
So maybe my sample is amorphous and some amount of crystals are growing on top of it as it is very concentrated (around 50 Wt%) or it is homogenously freezing?
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Yes
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Where the solution was mixed at different hours
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Dear Fatma Zeribi thank you for posting this interesting technical question on RG. I think it is rather difficult to give you a qualified answer because you did not specify what your reaction system is. Certainly it could be that longer stirring / reaction times e.g. in sol-gel processes give higher yields of titanium dioxide. In this context please have a look at the following potentially useful literature reference which might help you in your analysis:
Reactive crystallization: from mixing to control of kinetics by additives
This paper is freely accessible as public full text (please see the attached pdf file).
Good luck with your research!
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We put titanium dissopropoxide bis (acetylacetonate) in a freezing section for 1 day. Now the chemical is crystallized and segregated with the solvent. It won't go to a mixed state by itself. What do we do to recover the chemical?
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Dear Mikhail,
thank you for sharing this interesting chemical problem with the RG community. Commercially available titanium-disopropoxide-bis(acetylacetonate) normally comes as a 75% solution in iso-propanol. Chances are that in your case the compound just crystallized out of the solution upon standing over night in the freezer. Thus I think that slight warming of the bottle in hot water (ca. 40-50 °C) will leed to re-dissolution of the compound and formation of a clear solution again. If it does not dissolve again, this could be an indication the moisture has been sucked in and some hydrolysis has taken place.
Good luck with your work
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In the literature three crystalline forms (alpha, beta and gamma) have been reported for PLA. As I learnt they have different crystallization behaviour. Using the DSC technique, with a 'heat-cool-heat' programme in some samples, during cooling, I am observing a 'double peak' of crystallization, may it be connected with different crystal morphologies in the case of alpha and beta or what it can be? While conducting an experiment with quench those are not observed in cold crystallization. Also I'm not sure am I on the right way of understaning this. Thank you.
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Jaime Orellana Barrasa thank you for your thoughtful answer. Kind regards, MJY
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I need some literature about the role of ammonia in the vs2 crystal growth during the hydrothermal process. Can anybody help? Thanks
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Hello Hafiz,
sorry to see that your very interesting technical question has not yet received any expert answers. The hydrothermal synthesis of vanadium disulfide (VS2) can be achieved by reaction of sodium orthovanadate (Na3VO4x12H2O) with thioacetamide (TAA) in water. In the course of the hydrothermal reaction at 160 °C, ammonia is liberated which leads to formation of the unstable intermediate precursor compound of the composition VS2·NH3. In this material, ammonia in intercalated between VS2 sheets. This has been described in detail in the following fundamental research article:
Metallic Few-Layered VS2 Ultrathin Nanosheets: High Two-Dimensional Conductivity for In-Plane Supercapacitors
You can easily request the full text of this paper from one of the authors directly via RG (if you can't access it through your institution).
The intercalated ammonia subsequently assists in the exfoliation of VS2 nanosheets as reported in the following relevant literature references:
Vanadium Disulfide Nanosheets Synthesized by Facile Liquid-Phase Exfoliation for Ammonia Detection with High Selectivity
and
Emerging Layered Metallic Vanadium Disulfide for Rechargeable Metal-Ion Batteries: Progress and Opportunities
Unfortunately these articles have also not been posted as public full texts on RG. However, here too you can easily contact the corresponding authors via RG and request the full texts.
I hope this helps. Good luck with your research work!
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What is the concentration of the surfactants used in the protein isolation, purification and crystallisation of proteins and what is the basis for selecting the surfactant concentration in the different steps in proteomics?
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Dear Subhrajit Mohanty sorry to see that your very interesting technical question has not yet received any expert answers. Personally, I'm not an expert in this field enough to give you a qualified answer. My suggestion would be to search the "Publications" and "Questions" sections of RG for relevant literature refernces and for closely related questions which have been asked earlier on RG. Moreover, please have a look at the following potentially useful review article which might help you in your analysis:
Successful amphiphiles as the key to crystallization of membrane proteins: Bridging theory and practice
This article has been posted by te authors as public full text on RG so that you can freely download it as pdf file.
I hope this helps. Good luck with your work!
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After synthesis, I kept it for crystalization in the oven for 5-7 days. I have a few questions related to this:
1) Does sonication time affect the edges of MOF
2) at what stage do we take samples for TEM: after synthesis or after crystalization
3) Amount (weight) of MOF used to prepare the TEM grid
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1. Ultrasound creates areas of compression and tension in the material and therefore the processing time affects the inside and edge of the sample
2. TEM measures the distances between the electron planes of a crystal by Bragg scattering. Therefore, you need to wait for crystallization
3.There is a grid size. Why even more?
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When I was growing a single crystal recently, I found that the flux Sn residue on the surface of the single crystal was very serious. I repeated centrifugation, but it still didn't seem to work. I then soaked the single crystal with dilute hydrochloric acid (10%), but the single crystal is corroded. I think I should further improve the crystal growth process, so I wonder if there is any special way to overcome flux residue during crystal centrifugation. If you know, please let me know, thanks a lot.
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There are certain ways to minimize the flux on the surface of crystals.
1. Removing the flux at a little higher temperature. For example, you are using the Sn flux (melting point 231 C), so remove flux at 500-550 C followed by centrifuge at sufficiently higher rpm (~2000-3000 rpm is good).
2. Decrease the flux quantity.
3. Slowing down the crystallization process can also help in getting a good-quality crystal.
4. After centrifuge, use the dil HCl solution and sonication for a few minutes followed by sonication with ethanol/acetone. Repeat the process 3-5 times. The first sonication in dil HCl solution is a test rxn, to check whether it is affecting your crystals or not.
5. The SnCl2 is a white-colored compound. So you can stop the sonication with dil HCl when you observe when there is no change in a color beyond which HCl will start to attack the crystal itself.
For crystal growth, you may also refer to the following article as well.
The metal flux: A preparative tool for the exploration of intermetallic compounds
Hoping this will help.
Cheers
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Is there any optimum quantity of cristobalite (in terms of percentage) for a silica-based core to meet the requirements of turbine blade investment casting? How can I control this crystallization process?
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Dear Jose Antonio Reglero Ruiz I'm certainly not a proven expert in this field enough to provide a qualified answer to your interesting question. However, I very often made the experience that it can be quite helful using the "Publications" section of RG directly as a valuable source of information. For example, please have a look at the following potentially useful literature references which might help you in your analysis:
Investigation on Cristobalite Crystallization in Silica-Based Ceramic Cores for Investment Casting
and
Effects of Alumina on Cristobalite Crystallization and Properties of Silica-Based Ceramic Cores
Unfortunately these articles have not yet been posted as public full texts on RG. However, in both cases some or all of the authors have RG profiles. Thus you can easily contact the corresponding author via RG and request the full text. Perhaps you can even discuss your question directly with one of them.
I hope this helps. Good luck with your work!
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In social drinking scenarios, my preference has always been "on the rocks", but the ex/in-plosion mentioned in the title is quite new to me. I feel it's due to unusual crystallization or air trapped or whatever, as I pour water on remnants of broken ice in the tray. Can anybody give me a scientific explanation of it?
Thanks.
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In general, Dear Rad Maythil
What happens is a first-order transition from one state of matter to another one, which implies energy, that energy has to go somewhere. The explosion is part of that energy converted into sound energy (sound waves).
I rather would say that is some coalescence of drops of water that finally come together but in a very fast fashion. Probably I am wrong, but nothing else comes to my mind now.
Interesting question.
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Hi all,
I'm working on a protein complex crystallization. Luckily, I got some large thin layer crystals in following condition (Na cacodylate, ~10% PEG3350). However, when I tried to harvest these crystals, I found that they are very soft (just like the SDS PAGE?). Does anyone have the similar experience?
Btw, I have tried different temperatures, various PEG compositions and even additive screening, but I failed to obtain any better crystals (no diffraction pattern). How can I optimize the condition?
Thanks in advance.
Here is the crystal(?) image:
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It seems to be crystal but the quality of them is not good because their shapes are quite irregular. Irregular shape sometimes claims the protein molecules can not stack well with each other, which can explain why your crystal is soft. Of course, it is possible that these crystals are not protein, just other chemical like PEG. You can pick up one to run SDS-PAGE assay to test whether they are protein.
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One of the main hurdles which prevent the wide-scale adoption of cryonics as a valid medical technology is the issue of water crystallization in cells which lead to cell rupture. Have there been any advances made in literature recently to address this issue? Would appreciate links to survey articles, if available. Thanks
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Dear Rafiq Bodalal . This is really a very interesting topic. Suggest you read this paper. I found it very interesting
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What is the type of nucleation in Polypropylene composites containing carbon black (less than 3 wt.%) during crystallisation and recrystallisation?
Is it homogeneous, heterogeneous, secondary nucleation?
Specifically in the laser transmission welding process.
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Dear Foram Dave, it is well known that nucleation reduces spherolites size, hence important enhancement of properties are imparted to a polymer known by its high and large crystalline size domains. Please have a look at the following attached paper. My Regards
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Recently I stored two samples (Cell culture supernatant) collected on two consecutive days ( i.e. day 5 and Day 6) and stored in -20 0C, But after 7 days when I saw the samples, One sample is crystallized (as expected due to low temperature) but whereas other sample is still in liquid state, I'd like to know the possible reason for this ?
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Dissolved solutes like salt and DMSO can reduce the freezing point of a solution. Are the cell culture supernatants treated with anything or different in any way ? Else, it could be a technical issue. Change the place where you kept the samples to freeze and see.
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Hello,
I am trying to fit the atom. I tried to match PEG to density, because my crystallization condition contains PEG. But I can see the appearance of negative density after refinement. What other atom I should try ? The Electron density map is attached.
Thanks
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Thank you George Minasov for answering my question.
But, no calcium/magnesium was used in the crystallization conditions or in the protein purification buffer.
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my peptide molecule having free acid and gunidine group ,How can we crystallize and what are the best solvents for crystallization ?
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Hello everyone,
I am looking for fundamental level book for crystallization and its controlling parameters.
Could you please suggest any good recommended book ??
Please note: My area of research is *Struvite recovery from waste water* ?
Many thanks
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Dear OvGU fellow Salman Amjad, thanks for posting this interesting technical question on RG. There are several review articles and books available about this topic available. I would recommend to have a look at the following articles:
PHOSPHORUS RECOVERY FROM WASTEWATER BY STRUVITE CRYSTALLISATION: A REVIEW
and
Phosphorus recovery from wastewater by struvite crystallization: Property of aggregates
This paper is not freely available as public full text on RG. However, two of the authors have RG profiles. Thus you can easily contact one of them directly via RG and request the full text from him.
Also please check:
Phosphorus recovery from wastewater through struvite formation in fluidized bed reactors: a sustainable approach
(please see the attached pdf file)
I hope this helps. Good luck with you work and best wishes, Frank Edelmann
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How to extract peaks from X-ray test to calculate the crystallization ratio% of the material
  As well as the size of the crystal.?
When examining X-ray diffraction of any material, are you given the standard to x-ray with the examination?
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These two questions have been asked and extensively discussed here on RG, as well as other online resources, such as educational sites. A search for the two questions separately should give plenty of details for you.
If you feel annoyed that I don't bother to look for you and provide links, imagine how we feel when the question asker could easily do this for himself.
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Dear all
what is the new and HOT promising diluted magnetic semiconductor materials, that can have ferromagnetic and semiconductor properties close to room temperature? Wich not very difficult to realize (based on typical crystal growth techniques, availability of source)
My question is directed for research purposes, not necessarily for commercial applications.
Please share your knowledge. Additionally, If you know a good paper for this question, please tell me.
Thank you in advance.
Best regards.
Ismail
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Ferromagnetic chalcopyrites II-IV-V2 have Tc ~ 310-350 K and a diamond-like crystal structure compatible with Si and III-V semiconductors. Transition metal doping is possible in these materials over the entire range of concentrations from 0 to 100%. Here are two relevant references:
(1) Room temperature ferromagnetism in novel diluted magnetic semiconductor Cd1-xMnxGeP2, Jpn. J. Appl. Phys. 39(10A), L949-51 (2000);
(2) Magnetic and optical phenomena in nonlinear optical crystals ZnGeP2 and CdGeP2, J. Optical Society Am. B 22 (9), 1884-1898 (2005).
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Hi, recently I tried to do crystallization of a transaminase from Serratia sp. however, when analyzed I couldn't find Schift base or substrate in the active site nearby putative active site (K residue), but found PMP thus I predicted that the substrate was reacted during preparation and released as keto-amine. I was told that PLP-Glutamate or whatever amino acid can be synthesized before being mixed with protein before crystallization to make it observed in the structure. If you would like to share how the protocol for producing PLP-AA, it would be really appreciated. Thank you
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I found the method by myself ( ) and already try this method and got PLP-Glu for crystallization. 10 micromolar addition for the crystallization may be enough, I still hope to get a good crystal.
Thank you
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We know that amorphous polymers having the potential to crystallize can show peaks at DSC heat flow diagrams. The question is, does a polymer such as PLA, PET, etc. with a little amount of crystallinity (lower than its potential) show the same cold crystallization behavior?
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Dear Eren Dikmen, please have a look at the following RG thread and the other documents. My Regards