What is acidic component that is present in crude oil ? How is crude oil acidic in nature?

According to EN 12353:2013 microorganisms used in a laboratory must be stored under -70ºC or lyophilized. I'm currently working in a cosmetics laboratory that uses microorganisms such as P. Aureginosa, C. Albicans, etc. in several microbiologic tests. We buy microorganism stocks from a supplier, which arrive lyophilized and need to be stored according to the laboratory practices implemented, however, we don't have a way to store these in temperatures under -20 °C, so is it possible to store microorganisms at this temperature?

I'm working on predicting solar power output using machine learning, but I can't find a public dabases of solar power output with 1 minute step.

I only find databases with 1 hour step, and an other databases of irradiance with 1 minute step. So I decided to use this databases to calculate the power solar output for each 1 minute, and then use the results to train my machine learning model...

I've seen that there's a linear model that we can use to calculate the power solar output using irradiance.

Does anyone know how to find it ? or another solution ?

Hello to whomever is reading this.

I am working on HPLC analysis of anthocyanins in sweet potato leaves and tubers.

One of the methods I have found requires a mobile phase solvent of "5% formic acid in acetonitrile/water 1:1 v:v".

Do they mean 5% formic acid in acetonitrile 1:1 v:v?

Also, how do I prepare 5% formic acid from 98-100% formic acid? Do I just use C₁V₁ = C₂V₂?

Thank you for your help!

I just confused about heat generation and surface temperature of battery when I connect between parallel and series. Can anyone told me?

There are two types of mathematical models: Deterministic and Stochastic.

Explain them with proper examples.

I have two solutions of Polyethersulfone with different solvent. In one solution the viscosity increased up to shear rate of 1(1/s) and by increasing the shear rate viscosity is become constant. at high polymer concentration solution, the viscosity decreased at high shear rate(1000 1/s). How I can explain this behavior?

Hello Everyone,

The professor who I am working with has got an email from Biomedical Journal of Scientific & Technical Research (Biomedres) asking to support with "an opinion/mini review/case report, we hope 2-page article isn’t time taken for eminent author like you" (Angela Roy| Associate Editor).

To me it seems like a fake journal or one of those predator journals.

How can I check whether it is a predator journal and not a scheme?

Has anybody received "invitations" from this Journal before?

Thank you very much

Dear all, In machine learning, the most common way of splitting a dataset to obtain the training and test datasets is to randomly allocate the cases into one or the other taking into consideration the predefined p% of cases to be included in the test set. This approach will lead in some cases, particularly when using small datasets, to unbalanced training and test sets, that is, the training set may not contain extreme values of the predicted variable and/or combinations of the input variables. After training, the "whichever" learning algorithm is being used, will have, most likely, poor prediction ability and as a consequence a smaller applicability domain.

In what circumstances you decide not to randomly assign the cases but to force some of them to be present in the training set?

Do you, for instance, stratify your dataset into classes/bins reflecting the value of the variable(s) to be predicted and allocate a certain p% of cases of each class into the test set and (1-p%) onto the Test set, instead of randomly selecting the p% cases from the whole dataset? Do you stratify according to the predicted value or according to the input variables values?

Regards, Luis

I want to learn the COMSOL Multiphysics software (To be specific optical and heat transfer module). Can anybody suggest me a good tutorial to learn from beginning. I have checked some of the example (included in the application library) but I could not able to understand all the steps.

Thank You