ResearchGate Q&A lets scientists and researchers exchange questions and answers relating to their research expertise, including areas such as techniques and methodologies.
Browse by research topic to find out what others in your field are discussing.
- Can you recommend a method to time hydrogels gelation in small volumes?
I am looking for a reliable method for measuring hydrogel gelation time – one that gives more accurate results than tilting a gel until it appears to have finished gelling, or pipetting up and down until the gel doesn't pass through the pipette tip any longer.
Being able to measure viscosity would be an added bonus, but the priority is gelation time.
There are many basic looking gelation timers available (e.g. Gardco) but they use disposable paper cups that require a large sample size. Has anyone adapted one of these to be able to use a smaller sample size, e.g. as little as 1–2 mL?
Does anyone have experience using a more sophisticated piece of equipment, such as the HAAKE Viscotester 550 Rotational Viscometer in the link below? If so, would they recommend it?
You're technique sounds very interesting - Can you explain a little more about how it works or link me to an article on it?Following
- Any suggestions for plasmid/vector with both luciferase or GFP expressing and also HRE for expression of protein under hypoxic conditions?
Any suggestions for plasmid/vector with both luciferase or GFP expressing and also HRE for expression of protein under hypoxic condition. It is to construct bacteria that bioluminescence and also produces protein under hypoxic condition.
Excuse me,I don't think I actually catch what you mean here. But I'd wonder what plasmid do you use?Do you mean that you want to produce proteins in bacteira under hypoxia?Following
- Can anybody suggest where I can get different strains of Cowpea rhizobium (Bradyrhizobium strains)?
I am planning to conduct some experiments to measure nitrogen fixation in cowpea using a microbial biosensor and looking for Bradyrhizobium strains which nodulate cowpea. I am also wondering whether there are any Bradyrhizobium mutant (nif-), which inhibit nitrogen fixation in cowpea. Thank you.
Thanks for the replyFollowing
- How long it is need when spinup a CLM4CN model using my own atmospheric forcing, if I started with a previous simulated initial condition?
For example, I was trying to get a initial condition for the date of 1998-01-01. If I firstly ran a case using the default forcing CLM4.0CN to get the initial condition of 1998-01-01. And then using my own atmospheric forcing to drive the initial condition as the spinup, how long do I need to spinup the model?Following
- Why quenching under pressure is not widely used yet?
Quenching under pressure in liquid media allows governing of phase transformation in steels. It can be used for creation of nano - bainitic microstructure in large steel parts due to very fast cooling of surface layers. Probably, it will be widely used in the future in forging shops where forging and quenching could be combined. Such approach increases significantly strength of steel with the simultaneous improvement of its plastic properties.Following
- Which comes first, Creation or Innovation?
To be innovative you have to be creative.
Sajjad, Plato defined creativity in the Symposium. He used the word, poíesis, and said it was the process of making being out of nothing. Now, innovation, as I understand the word, means existing within a previous state ("in"), and without renouncing that state, making something "new" ("novum") within it. This is not strictly bringing into being a something that previously was nothingness.Following
- What is the least surface tension is possible with water? Which is best way to decrease the surface tension? Surfactant or boiling?
Does contact angle same in same surface tension of soap water and boiling water solutions?
Thank you Mr. Radomir I Slavchov for your answer. Cricitical temperature of water is 374°C. I need to get the least possibility in liquid state. We can reduce the surface tension by heat treatment or by surfactant. Does contact angle same in same surface tension of soap water and boiling water solutions on a similar solid substrate?Following
- How would government regulations impact the intrinsic motivation of a teacher?
As a progressive move, the Malaysian government has made the implementation of Outcome Based Education (OBE) compulsory in the country’s Higher Education Institutions thus requiring a major shift in the teaching paradigm.
Thanks very much Mr. Daugherty and Mr. Karlkoff.Following
- How can I decrease molecular weight of gelatin?
Dear all, I want to have liquid phase gelatin at room temperature with concentration of 5 Wt%. So I need to decrease the molecular weight of gelatin to 5 KDa. Please help me to achieve that. Thanks a lot.
Great suggestions so far, but I'll add another: Sonolysis - You can fragment gelatin into lower molecular weights (more soluble) using a sonicator.
Be aware, the proteolysis, hydrolysis and sonolysis suggestions will reduce your MW and make the gelatin soluble at high concentrations, but it will also reduce your gel strength and Bloom number.Following
- Can somebody provide me these two papers?
1. Differential Phosphoproteome Analysis of K562 Cells Exposed to 3'-Azido- 3'-Deoxythymidine (AZT). Current Proteomics, Volume 9, Number 1, April 2012, pp. 40-54(15)
2. Phosphoproteomic profiling of arsenite-treated human small airway epithelial cells.Oncology Reports, Volume 23, Number 2, 2010, pp. 405-412(8)Following
- Higher storage modulus, what does it means?
If there are 2 materials, the first one has higher storage modulus, what does it means? This is related to hydrogel. If one hydrogel has higher storage modulus, is it means that it can't swell quickly?
And what does it means to has decreasement in the storage modulus a long with increasement of temperature?
Hi there, the storage modulus is an indication of your hydrogel's ability to store deformation energy in an elastic manner. This is directly related to the extent of cross-linking, the higher the degree of cross-linking the greater the storage modulus. Swelling is also directly related to the degree of cross-linking, the more cross-linking the more swelling will be restricted.
So the answer to your first question, higher storage modulus means less swelling (assuming you re comparing hydrogels of the same type with different degrees of swelling).
If you are observing a decrease in the storage modulus with increasing temperature, it is most probably a result of non-chemical/covalent cross-links weakening.
It would be extra helpful to diagnose if you could provide more details on the type of hydrogel and cross-linker.Following
- May i know what is the significant of the value of heating value HHV and LHV for bio-oil?
pyrolysis of biomass producing bio-oil, and usually we will check the heating value for the bio-oil.Following
- I want to wish everyone a Merry Christmas and a prosperous 2015! How about a break in the works?
Another year is coming to an end and I want to wish everyone a Merry Christmas and a prosperous 2015!
As I am Carioca and I live in a beautiful city, here I leave a picture of my land in the celebration of this world party!
I am awaiting a little city of each of you too!
Thanks and the same to you AndreaFollowing
- Why are we all so forgetful? Is the crisis of economics over?
Only 5 years ago, most of economists questioned the present state of economics. See, for example, Victor A. Beker's analysis "On the Economic Crisis and the Crisis of Economics." http://www.economics-ejournal.org/economics/discussionpapers/2010-18
Paul Frimpong discusses in his recent blog post "Crisis of economics or Economic Crisis?" Part 1 and Part 2 http://www.modernghana.com/news/573340/1/crisis-of-economics-or-economic-crisis-part-1.html "what is the new economic thinking approach?" But this is rather an exception. Major scheme of economics did not change at all and we are beginning to forget the crisis which lies in the depth of economic science. Why are we all so forgetful? Is the crisis of economics over?
Bernard H Casey and all other readers
Newspaper is reporting rapid depreciation of Russian ruble. Some described it a "free fall." If Russia come to default, side effects will be great. I remind of the effectual bankruptcy of LTCM. It was the story of 19898.
One year before, there was Asian Financia Crisis. The crisis started by the attack of hedge funds on Thai Baht and spread to many Asian countries as an epidemics. Similar syndrome is appearing as the general fall of many Asian currencies.
Yes, Bernard. There is now a possibility of a second GFC (Global Financial Crisis).Following
- In pediatric population, is it possible to apply caloric test as a part of vertigo assessment?
It is well known that caloric test is one of vertigo investigations in adult population. is it the same for assessing a dizzy pediatric patient?
yes it can be ued.Following
- How to break gold-thiol bond?
Just curious, if a moiety has been attached to gold surface via thiol bond; then:
1. under what conditions it can be separated?
2. Is this bonding strong?Following
- How do I depolymerize natural rubber latex?
I am working on functionalization of natural rubber latex. I found out that it was difficult to functionalize high molecular weight polymer chain. Some recommended to depolymerize or cut NR chain. May I ask for recommendation of paper that report about method to do this?
@CC: since you mention functionalization of natural rubber, do you want to preserve the unsaturations in natural rubber polymer chains for later reactions? Bleach can add polar groups I think so you'll get a functional group, just wondering what functional group you wanted.Following
- How is the migration/invasion assay performed for non-adherent cell lines?
Medulloblastoma cell line D341 grows in a non-adherant fashion in clumps. They can be made into a single cell suspension using trituration. However, they do not invade in a Boyden chamber matrigel invasion assay. What are the other methods to carry out migration/invasion assay?
If you can get your cells to grow onto some sort of matrix, you can surround the matrix with type I collagen and hope they migrate out - worth a try and it is not that difficult; from the Fred Grinnell lab:
- Lona Do asked a question in Hospital architecture:Impact of sustainable hospital design on patients's treatment processes?
Hospitals, like all buildings, are both shaped by people and capable of shaping occupants’ behaviours and feelings (Gieryn, 2002). They are complex places that are simultaneously physical, social and symbolic environments (Gesler et al., 2004) The architecture of hospitals is, therefore, inextricably bound up with the forms of medical theorizing and medical practice which were operant at the hour of their construction and, what is more, all subsequent modifications to hospital design can be seen as a product of alterations in medical discourse,” Prior claims.
Hence somehow it has been believed that hospital designs effect to the patients's treatment processes. However which factors are having the best positive impacts on patients and how can we maximise their contributions?Following
- Can anyone help me which cells to consider as migrated cells, cells on the membrane or cells in the lower chamber?
I have some problem in migration assay. In the migration assay, which cells are better to consider as migrated cells, cells on the outer surface of membrane ( transwell insert ) or the cells transferred to lower chamber?Following
- Can anyone suggest how to find Electrical Conductivity of Electrochemical (Polyaniline deposited sulfonated PEEK) Membranes using Gamry Potentiostat?
I have deposited Polyaniline on sulfonated PEEK membranes through In situ solution polymerization. I want to calculate electrical conductivity using Gamry Potentiostat.
If your resistance is high in kilo ohms and above, you can go for two terminal measurement also instead of four terminal measurements suggested above. For this purpose make good electrical contacts at two places on your film and measure current at an applied voltage. If you are in megaohms resistance range and above, mount your film in a metallic sample holder with vacuum inside for electromagnetic shielding.Following
- How can I make a good single layer graphene film?
I made some graphene films using CVD technique. But Raman analysis showing no 2D. How can I make a good single layer graphene film and what are those precautions I have to maintain?
Thanks Kranthi Kumar for your answer, and of course everyone here know about exfoliation techniques … Rather, I mentioned this new method because it allows patterning graphene where you want, which is a little more difficult to do from exfoliation I think.Following
- Can any one suggest me a research paper on Drug toxicity ?
It should be a paper from a journal which has Impact factor 5 or above 5.
- Does “spin” imply physical rotation?
The “spin” of an electron or other fundamental particle is often described as “intrinsic angular momentum”. This terminology is required because a point particle or Planck length vibrating string cannot possess ½ ħ of angular momentum. Larger objects such as molecules or electrons in atomic orbitals possess quantized angular momentum which can be demonstrated to involve physical rotation. For example, a carbon monoxide molecule in a vacuum can only rotate at integer multiples of 115 GHz which is integer multiples of ½ ħ. Therefore, do you believe that fundamental particles have a physical angular momentum that is currently not understood? Alternatively, is "intrinsic angular momentum" an accurate description of spin because it is a quantum mechanical property that does not involve physical rotation?
I recommend looking up "spherical rotation" (as distinct from cylindrical rotation) which has been shown to explain all electron properties in a tensile medium.Following
- How can I maintain the LNCaP cells properly?
I am maintaining LNCaP cells and facing various problems. I was observing black dots in my culture previously.so, I re -filtered media and started growing fresh cells. That problem ended there , but during trypsinization , I always see those dots, but now they goes after changing the media of cells 2-3 times. Does these black dots normally appear in LNCaP cells during trypsinization or this is due to some handling error? secondly, when I subculture these cells, their distribution do not remain uniform all over the 100mm plate despite of my sincere efforts to equally distribute the cells after plating in new plates ? what can be the reason for this? somebody has suggested me that ,this is due to the clumping of cells. so, if this is the case how to avoid this thing? It is generally said to pipette up and down the cells to break the clumps. so, How many times this should be done to make sure that single cell suspension is ready ...Thirdly, how much trypsin I should use for 100 mm plate and for how long and how much complete media to use to inactivate trypsin? and after trypsinization, some protocols says to tap cells and some strictly says not to tap the cells? so, what should I do? and lastly, I need to change the media of cells after every 24 hrs. at around 40-50 % confluency, but ATCC suggest twice per week. Does this rapid exhaustion of media is also a problem? Please do suggest me to overcome these problems.Following
- Can I do a case study with a supernormal case?
As far as I know, most of the case studies are based on clinical cases. I wonder whether it is acceptable to do a case study with a supernormal participant. I searched it with Google, but found nothing. Have you seen some studies related to supernormal cases?
Thanks a lot, Fiona. Take care of yourself.
I may have find it.
How to do your Case Study: A Guide for Students and Researchers
- Which software do you prefer for Text Analytics (SPSS vs. RapidMiner)?
Researchers interested in data mining can decide between SPSS Text Analytics for Surveys or open source softwares like RapidMiner and specific modules on R language. Which one do you think is better accepted by the academic community?Following
- How can I quantify the density and stability of amine groups formed on the surface of plastic optical fibers?
This is with regards to PMMA surface modification.
If you just want a measure of how many amines you've introduced, try the ninhydrin assay. It's quick, cheap and sensitive. If you want to map out the density on the surface, then as Andreas suggests your best option is to label with something you can visualise (e.g. a fluorophore).Following
- Should the effluent of secondary treatment of pulp and paper plant be reused for irrigation?
A free chlorine plant of pulp and paper will be installed near Orinoco River and the effluent has to be reuse because it not will be discharge to the river, the concentration of BOD wil low but the COD will be around 800 mg/L and the real color will be high too. The secondary treatment will be an activated sludge process selector type.
Colleague Ashutosh is raising a good point and I do agree that chlorination of C rich effluent could potentially produce chlorinated hydrocarbons. From a risk assessment viewpoint I still maintain that any such discharges are less risky to land than that to water.
From an environmental risk assessment viewpoint soils can buffer wastewater with high BODs but most receiving waters cannot unless 'dilution' is the only solution. High C disposal to soil will be beneficial to soils but detrimental to freshwater or seawater environment. Moreover, as for potentially harmful chemicals, for example chlorophenols are volatile (which means this is one of the loss processes) and can be biodegraded by soil microbes (i.e.not all chlorinated hydrocarbons are considered as persistent). Even if they are persistent (potentially take a long time to breakdown) the question should be whether the chemicals can enter the food chain, i.e. taken up by crops/pasture.
Yes, a small trial should answer some of these questions.Following