Crystallization - Science method

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

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.

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.

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.

Yes, the peak before the melting peak in your DSC heating curve is likely due to cold crystallization.

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,

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

@Joshua Depiver

Thank you for your kind answers!!

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).

Dear friend Sheetal Tresa Fernandes

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:

(1) Can anyone please suggest the best method to grow the crystals for .... https://www.researchgate.net/post/Can_anyone_please_suggest_the_best_method_to_grow_the_crystals_for_organic_compounds.

(2) Crystal Growing Tips - The Center for Xray Crystallography. https://xray.chem.ufl.edu/helpful-information/crystal-growing-tips/.

Marcella Bini Andreas Leineweber

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.

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.

Igneous rocks are rocks formed from the crystallization of a liquid (molten rock). Igneous rocks may be divided into two categories. Intrusive or plutonic rocks crystallize from magma beneath the earth's surface. Extrusive or volcanic rocks crystallize from lava at the earth's surface. Rock becomes buried deep underground. Intense heat and pressure melt the rock into magma. The magma cools and solidifies into Igneous Rock.

I have abundoned that field research long ago and cannot help you much.

Prabal Dasgupta

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

Amid Laxman Sadgar

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.

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.

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.

Time zero?

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.

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.

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.

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.

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

Eduard Rusanov Thank you very much! I'll try to refrigerate the mixture and see if anything precipitates.

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

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.

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.

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!

Thank you

"... 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.

Also check please the following useful RG links:

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.

Yes

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:

This paper is freely accessible as public full text (please see the attached pdf file).

Good luck with your research!

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

Jaime Orellana thank you for your thoughtful answer. Kind regards, MJY

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:

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:

and

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!

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:

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!

Rahul Verma

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?

Hi Ziming Wu

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

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:

and

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!

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.

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.

Dear Rafiq Bodalal . This is really a very interesting topic. Suggest you read this paper. I found it very interesting

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

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.

Thank you George Minasov for answering my question.

But, no calcium/magnesium was used in the crystallization conditions or in the protein purification buffer.

Vishnuvardhan Nomula check..

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:

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:

(please see the attached pdf file)

I hope this helps. Good luck with you work and best wishes, Frank Edelmann

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.

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).

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

Dear Eren Dikmen, please have a look at the following RG thread and the other documents. My Regards

Chian Heng Lee ,yes, all of my samples match the diffraction pattern of SrB6, having no significant change in the lattice parameter, thus the same space group. Also, as part of our experimental process, we get rid of oxides using an acid wash of HCl/H2O, which makes interesting the overall results of Li concentration.

Because of the low solubility of the ligands and the difficulty to grow crystals of coordination polymers, ay idea and suggestion?.

Dear Tanya Srivastava this is a very interesting and important technical question. In this context please have a look at the following potentially useful literature references which might help you in your analysis:

and

Fortunately the first articles has been posted by the authors as public full text on RG, so that you can freely download it as pdf file. The author of the second paper is an RG member. Thus you can easily contact him via RG and request the full text directly from this author.

Good luck with your work and please stay safe and healthy!

Dear Flo Do thanks for sharing this interesting technical question with the RG community and sorry to see that it has not yet received any expert answers. I'm not familiar enough with the experimental setup, but my initial thought was if you can't just use distilled water to keep the humidity stable in your closed chamber? In any case I would try to avoid any dissolved salts. Instead of using salts you can perhaps use a mixture of e.g. glycerol and water.

Good luck with your work and best wishes, Frank Edelmann

I am old-fashioned (geology-mineralogy-chemistry-advanced-level geosciences, .e.g., isotopes).. Therefore, in this case where only a chemical ratio forms centerpiece of a discussion of such a far-reaching issue, I can only respond in a way like that:

"One swallow does not make summer"

HGD

Hi Frederik Link,

Hard to tell what is going on since lysozyme crystallizes very easily.

First, I would dissolve the lysozyme and leave it for a while (maybe sonicate a little?) to ensure complete dissolution.

Maybe measuring the pH of your mixture could indicate that something is off; if the pH is too far from ~5 (the pH of your sodium acetate buffer), this could possibly lead to the precipitation in the drops.

Another idea is to check the lysozyme concentration by absorbance. If, by accident, you are using a too higher concentration, this could lead to precipitation.

I would also run an SDS-PAGE gel (or MS, even better) to check the purity of your lysozyme powders.

Best,

Italo Cavini

Hello Deepak, this is clearly an important technical question which is of broad general interest to many other RG members as well. Virtually every organic or inrganic chemist is frequently faced with the problem of how to grow single-crystals of new compounds which are suitable for X-ray diffraction. Quite often this is more an art than just a technique. There are many different ways you can try the crystallization, such as cooling of saturated solutions in suitable solvents of solvent mixtures, layering with anti-solvents, solvent diffusion techniques, sublimation etc.

For some general information about this important issue please have a look at the attached guides to crystallization. These will provide you with an initial overview. I hope this helps. Good luck with your crystallization and best wishes, Frank Edelmann

Nakia,

If you would like to look professional in crystallography, I would recommend to reindex your data in the proper space group, P21212.

there are only P222, P21212, P2221, P212121.

In the case P21212 and P2221 you can reindex your data to have properly chosen 21 and 2 fold axes.

Good luck!

Dear Po-Hsi Lin thank you for posting this interesting technical question on RG. The ion exchange as suggested by Florian Morsbach is perhaps the most elegant method for preparing the free phenylbutyric acid from sodium phenylbutyrate. If you are not familiar with the use of ion exchangers, you can also add HCl or sulfuric acid until the solution is acidic, and then extract the free acid with diethyl ether (3 times). Dry the extract with anhydrous Na₂SO₄ or MgSO₄ over night, filter, and evaporate the filtrate using a rotary evaporator. The residue can be purified by distillation under vacuum as described in the attached literature reference. When the sample is pure, it will crystallize at room temperature (melting point 46–48 °C).

Good luck and best wishes, Frank Edelmann

Dear Sidarth, many thanks for asking this very interesting technical question on RG. Crystallization of yttrium nitrate hexahydrate is quite simple and straightforward. First of all make sure that you have a clear solution in water. If some turbidity persists, you can add a small amount of nitric acid to redissolve any insoluble material. It is no problem if the solution is slightly acidic. Then place the solution in a beaker (in the fume hood) and heat it to boiling on a hot plate while you stir it with a magnetic stirring bar to evaporate the water. As soon as the first solid material appears on the surface, stop heating, remove the stirring bar and let the solution cool to room temperature over night. This will lead to copious formation of crystals. You can isolate them by decanting the supernatant and dry them on filter paper. Further cooling of the supernatant solution to 0 °C can lead to an additional amount of crystals.

Good luck with your work and best wishes, Frank Edelmann

You write: ".I use the proper conditions for the protein" - You cannot assume that a modified construct (e.g. His-tagged) will crystallise under the same conditions than the unmodified one. Very small changes in a protein can have a large effect on its behaviour in crystallisation trials, be it due to the modification interfering directly with a crucial crystal contact, or due to a more global effect on solubility, e.g. by altering the isoelectric point of the protein, protein stability, etc.

If a structure of the non-tagged protein is already available, you can check how the tag is located relative to the observed crystal contacts, and assess if it could be accommodated in the lattice - in this case, there is a good chance that proper conditions for the purification can be found by fine-screening around the conditions conductive to crystallisation of the un-tagged protein. If the tag directly interferes with crystal contacts, you would have to find a different crystal packing, that means having to do a wide screen for new conditions for the altered protein.

@Ali Mohammadnejad what should be the heating temperature and heating time.

Hello, the endothermic peak at room temeprature is probably due to melting of the crystalline regions. EPDM is a copolymer containing ethylene sections that can crystallize: depending on the lenght of the ethylene sections, large or small crystallites can form. The size of crystallites affects the melting temperature, which can fall in the room temperature region. Concerning the exothermic peak, it is likely due to cold crystallization of the amourphous polyethylene regions. Upon heating, amorphous sections can gain enough thermal energy to rearrange in a crystalline form, and the relevant energy exchange is the reason for your peak.

Post a spectrum for better evaluation!

It is not an effective mass gain, it is the impulsion effect of the hot gas inside the thermobalance oven. You must correct the mass sign with the curve corresponding to the blank test (both empty crucibles or containing an alumina suitable for the effect, stable for T<1200ºC).

Hi Yanmei Peng , Have found any suitable software? I am also looking for a possible software to simulate salt crystallization and have come across this question of yours.

The stock solution should be stored at -20 °C in aliquots. By thawing small volume it will prevent formation of crystals.