Selecting particular columns from large datasets (csv) using R Studio?

So I have large number of csv files (100+) in a directory with same structure and column names. The data is in time series and there are approx 30 columns/file. However i only want to aggregate...

08 February 2021 245 5 View

How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for Metabarcoding?

I'm working on pollen DNA metabarcoding to identify the floral composition of honey. How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for the...

28 December 2020 9,132 1 View

How to add two vertical and parallel Fresnel reflection coefficients to retrieve overall reflection coefficient for a right hand circular wave?

I have a problem in which a right hand circular polarized wave (GPS wave) encounters an ideal smooth plane obliquely, and then is reflected off that. To solve this kind of problems, the wave is...

28 December 2020 2,271 3 View

Which is better to focus on teaching or research for a good academic life and Why?

Which is better to focus on teaching or research for For a good academic life and Why?

26 December 2020 5,737 9 View

Is ag paste suitable for back contact on silicon wafer? or i should deposit al on the back surface using pvd or plasma sputtering?

Fabricating silicon solar cell

22 December 2020 4,906 7 View

Which renewable source is the best ?

wind hydro solar etc.

21 December 2020 6,360 16 View

Why is light pure energy?

light is pure because the light is the simplest electromagnetic construct but the energy of any object is also of the same kind.

20 December 2020 207 4 View

How to handle Missing Values for Skipped Questions (Systematic Missing) in R ?

10 December 2020 435 4 View

What is the best industrial emulsifier to make silicon oil in water emulsion?

I need to make long-lasting stable emulsions of 6 wt. % percent silicon oil in DI water. The previousely made emulsions using Tween and Span Emulsifiers did not remain stable after a week.

31 October 2020 3,568 3 View

Carbon Emission calculation factors ?

I am thinking about writing a paper on carbon emissions based on electricity consumption data from some buildings. From a research perspective, which factors should i specially focus while...

09 October 2020 4,142 3 View

What is Nano technology with coronavirus helpe the human..and is it nano mterals removal of covid19?

I anwar by adsorption or reaction ..but it is either more method...

02 March 2021 4,811 2 View

How to compare different concentrations of nanoparticles for characterization from ICP-MS?

I took measurements of different concentrations of 15 nm and 5 nm Au nano particle solutions. I'm trying to determine which concentration I measured gives the best reading overall. I also...

02 March 2021 7,626 1 View

1 nm thick MgO thin-film to be deposited on Si wafer using thermal evaporation. What will be the optimum deposition conditions?

Favourable conditions of base pressure, rate of deposition. Also, by which characterisation technique to be used to verify the thickness of the deposited film.

28 February 2021 3,640 3 View

LEDs on Vis Light photo degradation of MB water sol via N doped TiO2 in a mini flume?

Good day to all, I have no experience with light emitting diodes. I am building a glass mini flume to demonstrate the photo degradation of Methylene Blue in water running over self cleaning...

26 February 2021 4,026 5 View

Zno nano particles colour changed from white to grey in process of calcination any suggestions?

In the formation of Zno nano particles process, after drying at 120 degree C, my zno nano particles are completely white but when i calcine it for 450 degree C it converts into grey colour. i...

26 February 2021 2,435 4 View

Is there an ideal incubation time of RGO-modified SPCE before subsequent use, i.e., electrochemical characterization or further modification?

I notice that upon washing and air-drying of my RGO/SPCE surface and characterizing again via DPV, the current response towards ferricyanide probe significantly decreases. My worry is that the...

22 February 2021 5,324 3 View

How can I measure the thickness of thin layers deposited on textured glass susbtrates?

I want to measure the thickness of aluminum oxide and titanium oxide layers deposited on textured glass substates. The layer thicknesses are typically below 100nm.

21 February 2021 5,465 4 View

What is the best etching method for Mg-Ca alloy?

I have used Picral etchant (4.2 g Picric acid, 10 mL Acetic acid, 70 mL Ethanol, 10 mL distilled water) but it didn't work. Is there any alternative?

21 February 2021 2,558 5 View

QPCR tubes for Roche Lightcycler Nano?

We own a small cPCR thermal cycler from Roche, Lightcycler Nano, which is convenient for backup quick runs. Recently, Roche has discontinued the plastics for it and they offer no alternative from...

17 February 2021 8,694 5 View

Charmm/GROMACS Residue 'ZN' not found in residue topology database?

I am trying to do some MD simulations of a protein with zinc ions. I am trying to use a charmm forcefield (I have tried 2017 and 2021) and Gromacs. I get an error when doing pdb2gmx Residue 'ZN'...

12 February 2021 9,367 2 View