Detectors - Science topic

Yes, size and zeta are different. IF you have a ZS90 then they detect at different scattering angles. zeta is in forward angle. size is at 90 degree angle.

If you are a novice to the Zetasizer you might find this video tutorial helpful:

Thank you for your answer Poorya Rahdar Poorya Rahdar

Do both detectors have the same parameters? Are both collectors equal? Are you using two equal columns with the same measurement parameters? The difference is too large and that's not logical. both detectors and columns with the same conditions of measurement should bring approximately the same chromatograms with approximately the same results.

Dear Hamed Sabouri ,

thanks for feedback.

You still apply voltage to the detector; otherwise you would not see any peak; but the voltage may be too small.

Please have a look at the manual and/or the specifications of the detector for the HV value. Such values are in the range of about 1500 to 2000V.

So please increase your HV in a few 50V steps, and see whether the background gets smaller and the 60keV peak gets narrower.

Good luck and

best regards

G.M.

For detecting metals on the human body, effective techniques include:

These approaches enhance the accuracy and effectiveness of metal detection on or near the human body.

Trazendo uma atualização Fabio Dossi :

Em System Parameter tem informações sobre Gnio radius(mm), Distance between Ds and X-ray Focus(mm) (ver imagens anexas).

Próxima semana estarei novamente no laboratório e verificarei com o técnico outras opções.

William Bray Thanks for your helpful advice.

Glucose should seperate just fine on just C18. or you could try something crazy like Chirobiotic-T. but that column is very expensive.

Have you been able to solve the problem?

Dear Johan K. Fremerey ,

This morning I answered your question first. It seems that the reply was not sent due to my carelessness.

That's about all it contained:

This whole LIGO gravitational wave narrative is a huge hoax. I have been four weeks in China, came back yesterday (2024.10.13). There were opportunities to perform simple experiments that could be used to prove that the prediction of the my theory of gravity gives a positive result.

and quoted the wise remark of the late W.W. Engelhardt from:

How do they know that the velocity of light is unaffected when "spacetime" is "compressed"?'

Regards,

Laszlo

'

Derivatization of glucose to introduce chromophores could improve PDA detection. 1-Phenyl-3-Methyl-5-Pyrazolone (PMP) is a common reagent for derivatizing glucose. It reacts with the reducing ends of glucose, forming stable products that absorb strongly in the UV range (typically around 245-250 nm).

The glucose is reacted with PMP in alkaline conditions (e.g., with sodium hydroxide), and the resulting derivatives are stable for HPLC analysis.

You can use a C18 reverse-phase column after derivatization. Since PMP makes the glucose derivatives more hydrophobic, a C18 column would provide good retention and separation.

A typical mobile phase might be acetonitrile with water or a buffer system (e.g., phosphate buffer) for gradient or isocratic elution.

*Fluorescence Lifetime Measurement (FLIM)*

Principle:

1. Excitation: Diode laser emits continuous wave (CW) light.

2. Fluorescence: Sample emits fluorescence in response.

3. Lifetime measurement: Detect changes in fluorescence intensity over time.

Setup:

1. Diode laser (cw)

2. Sample chamber

3. Photodetector (e.g., PMT, APD)

4. Data acquisition system

Measurement steps:

1. Illuminate sample with cw diode laser.

2. Detect fluorescence signal.

3. Measure fluorescence intensity decay.

4. Analyze decay curve to extract lifetime.

*Lifetime calculation:*

1. Exponential fitting: Fit decay curve to exponential function.

2. Lifetime (τ) calculation: τ = 1 / (decay rate)

*Advantages:*

1. High sensitivity

2. Fast measurement

3. Non-invasive

*Applications:*

1. Biomedical research (e.g., protein binding, cell imaging)

2. Materials science (e.g., quantum dots, nanocrystals)

3. Photovoltaics (e.g., solar cell efficiency)

*Diode laser specifications:*

1. Wavelength (e.g., 405 nm, 633 nm)

2. Power (e.g., 10 mW, 100 mW)

3. Stability (e.g., <1% intensity fluctuation)

*Common fluorescence lifetime ranges:*

1. Biological samples: 1-10 ns

2. Organic materials: 1-100 ns

3. Inorganic materials: 10-1000 ns

Create a method with a flow of zero (0.0), detector lamps OFF and add it to the sequence of methods.

In general, in chromatography, detectors are essential for identifying and quantifying the compounds that come out of the chromatography column. They convert the physical or chemical properties of these compounds into a measurable signal, which is then analyzed to determine the presence and concentration of each substance. The following are some of the types of detectors commonly used in chromatography: 1. Ultraviolet and visible detectors: These detectors measure the absorption of ultraviolet or visible light by compounds as they pass through the detector. They are widely used because many organic compounds absorb ultraviolet or visible light, making this method versatile and relatively straightforward. 2. Fluorescence: Detects compounds that glow when exposed to specific wavelengths of light. Common Uses: Highly sensitive and selective; used for compounds that are naturally fluorescent or can be derived to be fluorescent.

BSI also sells the CR-39 through Amazon now.

The link below shows an electron microscope large area mapping of the CR-39 that has been exposed to Am-241

So it seems you have two issues, both detection and separation? Maybe the free online booklet "A Practical Guide to HILIC" (available on ResearchGate, although it quite some years since we wrote it) could be a source of useful tips for you? For the separation I recommend you stick with acetonitrile since methanol tend to give too much hydrogen bonding thus competing with the HILIC retention mechanisms and weakening the immobilized water layer that contributes to retention. You might need 70-90% acetonitrile for sufficient retention (more ACN = higher retention). Salt levels often need to be higher in HILIC compared to reversed phase due to the electron rich nature of separated compounds and the stationary phases. For detection; can you find glycerol in UV or RI without the column? In UV you might need lower wavelengths, but in RI there is often not much to do other than having a sensitive detector and increasing the concentration of the analyte. Also keep the temperature stable to avoid drift in RI.

Thanks, Markus for your help.

I have uploaded a document with screenshots of the refinement with some magnifications in some areas so you can see the profile of the peaks. Also, I have set the SRT that I am using to refine the profile.

Finally, the LaB6 is a NIST660C.

A diode-array-detector ("DAD"), photodiode-array-detector ("PDA") and multi-wavelength-detector ("MWD") are usually the same type of variable wavelength UV/VIS detector, with the names "DAD" and "PDA" names used interchangeably by different vendors. They are ALL UV/VIS detectors where the user can acquire multiple UV/VIS wavelengths at the same time (usually 5 to 8 different or "Multiple" signals) which is mandatory when performing basic HPLC method development on compounds with chromophores. The "DAD" and "PDA" have one additional feature that the "MWD" does not. In addition to being able to acquire multiple wavelengths, the "DAD" and "PDA" also can acquire full scanning data across the entire range of wavelengths (e.g. 190nm to 800nm). This powerful feature allows you to 'see' / detect sample peak absorbance across ALL wavelengths during each analysis run. For method development and/or any type of QC analysis, this comprehensive 3D data provides the user with additional information regarding the possible presence of impurities (a null test), qualitative ID and/or the presence or absence of specific compounds. A requirement for any type of professional analysis by HPLC or LC-MS (inline DAD plus MS offers one of the best detector configurations for HPLC analysis as neither detector is "universal" and neither detector can detector all compounds present. Having both in-line detectors, used with appropriate methods and training, provides additional orthogonal information).

Yes, the described method using a Thermal Conductivity Detector (TCD)

Both, HPX-87H column and RI detector should be suitable for separation and detection of organic acids. However, I don't know either, if something is missing in method as I don't know your method. If you could provide some more information like solvent composition, standard concentrations, maybe a chromatogram, that'd be helpful.

I'm seeing everything you are seeing with this poorly designed instrument, except for column bleed (which is probably something else).

Become an O-ring Guru. Order your O-rings (all of them, because you'll find the cold trap O-ring is equally irritating...I use many different types of cold trap packing material, so I change them out often) from Parker O-rings; they go sell through distributors and they have many distributors. Paying an arm and a leg through Perkin Elmer isn't necessary.

Also, I don't use Tenax; it creates too much trash for my liking and the temp is too low before it does produce trash.

Get creative and find the packing material that works for you. After all, most materials will trap compounds at -30 degrees celsius and you don't need material that strongly selects via size or intramolecular forces in the cold trap. Keep it simple....for example, I calibrate using 420-600 micron glass beads in my desorb tubes and cold trap. I don't need the complication of desorption efficiency unless it is imposed upon me. Plus, you can run a high trap temp with glass beads and clean them if you accidentally get a stubborn compound stuck to it.

What is the retention time for the peak in acetonitrile? What is the retention time in methanol?

"Ghost" peaks come from contaminants. Null runs without injections showing the peak tends to rule out the injector as a source of the peak. The peak seems very reproducible.

One source of ghost peaks are contaminants in solvents. It could be the formic acid or water, you still saw the peak when you tried methanol which suggests the acetonitrile might not be the source.

If you post a chromatogram, it would be helpful.

there Are MANY orders of magnitude difference in sensitivity ( I guess more than 10) between the LIGO experiment and your Lecher line. Although there exist some basic similarities.And please remember the very old Michselson experiment about the absence of aether (anisotropies)

Dear mahsa

Is there any leakage from the flow cell ?

second, try to replace the column ..what the result ?

Last , try to reverse the detector connections (outlet in the inlet ) then flush with isopropanol (HPLC grade) for about 5 min .. then reconnect the system in the correct direction ..

yes the manual as many others are available on:

DigiKey an electronic reseller has the fiber optics cables needed to connect the different units to the SCL-10A for $13 rather than ~$50.

The cable is: Broadcom fiber optic HFBR-RMD001z

Good luck

Efficiency refers to the proportion of particles detected, without any dimension (unit), but sensitivity is defined as the amount of current, voltage, or charge that a detector or detection system can obtain per unit radiation physical quantity (detection object) of a certain radiation field when operating in a linear dynamic range, and therefore has a dimension (unit) of physical quantity.

Yes, it is better to know if the compound is volatile and thermally stable before you can run direct GC-MS . Also, run UV spectra from 200-400 nm to check if it has any absorbance in the range. If non-active you can only use HPLC with an ELSD detector to determine the purity first. There are other ways to find the structure such as NMR.

G. Knoll, Radiation Detection and Measurement:

Thanks for answer! But there is a difficulty to turn on this function..

Thanks, task has be completed. Cheers

See this paper . Its clearly explained. CR-39 is sensitive to alpha radiation of both radon and thoron. therefore it can not be directly done with only one CR-39. but the idea in this paper is they use two cr-39 enclosed in plastic boxes. one has a sponge surrounding the chip. this stops the Thoron from diffusing into it, thus it only measure alpha from radon. The other measure alpha from both radon and thoron. There is an equation that takes the difference and give the thoron concentration

Dear Dr Vijay Arjun Bagul

Since my lab have no OPA and the order is still in process, thus, I came up with the idea to find another possibility to analyze SMM without OPA.

I found several references that analyzed SMM without OPA, I followed those papers but I'm still failed.

The consciousness of the universe is a different matter (I posted a question on this several years ago) to a supreme being which simply reflects human society. The idea of course that that being is specifically here for humankind, an inconsequential being surely in such a vast universe, gives clear evidence of its falseness.

Certainly, troubleshooting a CAD (Corona Discharge) detector that is not working properly can be challenging, but there are several common issues and steps you can take to diagnose and potentially resolve the problem. Here are some troubleshooting steps:

1. Check for Power Supply Issues:

- Ensure that the CAD detector is receiving the correct power supply voltage and current as specified in the instrument's manual.

- Verify that all power connections are secure and that there are no loose or damaged cables.

2. Inspect Gas Flow:

- Check the gas flow rate and pressure. Inadequate or unstable gas flow can affect the performance of the CAD detector.

- Inspect the gas lines and connections for leaks or blockages.

3. Clean the Electrodes:

- The CAD detector typically has two electrodes. One electrode generates the corona discharge, and the other detects ions.

- If the electrodes are dirty or contaminated, it can affect the detector's performance. Clean them carefully following the instrument's manual.

4. Check for Contaminants:

- Contaminants in the sample or carrier gas can interfere with the CAD detector's operation. Ensure that the sample is clean and free from contaminants.

5. Calibrate the Detector:

- Recalibrate the CAD detector according to the instrument's calibration procedure. Incorrect calibration can lead to inaccurate results.

6. Inspect and Replace Consumables:

- Some components in the CAD detector, such as the corona discharge needle or collector electrode, may need regular replacement. Check if any consumables are overdue for replacement.

7. Review Data and Settings:

- Examine the data output from the detector to see if there are any unusual patterns or signals.

- Verify that the instrument settings and parameters are correctly configured.

8. Check for Interference:

- Some substances in the sample may produce interference with the CAD detector. Review the sample composition and the possibility of interferences.

9. Consult the User Manual:

- The user manual for your specific CAD detector model will often have troubleshooting guides and recommended maintenance procedures. Refer to it for detailed instructions.

10. Contact Technical Support:

- If you have tried the above steps and the issue persists, it may be necessary to contact the manufacturer's technical support or a specialized technician for further assistance.

Remember that working with analytical instruments like CAD detectors requires care and precision. Always follow safety guidelines and the manufacturer's recommendations when troubleshooting or performing maintenance. Additionally, document your troubleshooting steps and any changes made to the instrument to aid in future diagnostics and maintenance.

Leonid Vesselov Thank you very much.

If you are working in vacuum, the conventional methods are to accelerate them first (to increase their energy) and then use something like a multi-channel plate. This typically will only determine if they are present or not--it does not directly measure their energy. If you search for work measuring the recoil protons from neutron beta decay you will probably find good discussions of the issues.

Sorry, I am a gas-solid surface guy and the things I can tell you about solution are things you hopefully have already learned yourself.

Yes, you often can. It has less to do with what brand and model the other instruments are and more to do with the chromatography software you use to collect and analyze the data with (The "CDS"). Depending on the data output format of the FLD detector and the expected data input format needed by the instrument, you may need to use an A/D converter. The FLD detector's output will need to be connected to the "other" system (this is usually the easy part). *While most detectors can be used in this way, you may not have full software control over FLD excitation and emission wavelengths. Check with your CDS vendor's documentation to find out which FLD it supports and is compatible with.

Dear Olivier Briot ,

please see for at least for the North East detector:

'-250V' at the type label

Best regards

G.M.

Please FIRST provide your DETAILED HPLC method and a chromatogram for useful suggestions.

Nikhil Verma

In XРS ( X-ray photoelectron spectroscopy) measures the binding energy of electrons with a nucleus when irradiated with monochromatic radiation, which appear as a result of the photoelectric effect.

Scanning electron microscope (SEM). The incident electrons interact with the atoms in the sample, creating various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned as a bitmap and the position of the beam is combined with the intensity of the detected signal to produce an image.

Energy dispersive X-ray spectroscopy(EDX). The electron beam is focused on the sample and transfers electrons from one shell to another. This releases X-rays. The amount and energy of the x-rays emitted by the sample can be measured using an energy dispersive spectrometer. Since the energies of X-rays characterize the difference in energy between the two shells and the atomic structure of the emitting element, EDS makes it possible to measure the elemental composition of the sample.

XRD identification of materials based on their diffraction pattern. The sample is irradiated with X-rays and the intensity of the rays leaving the sample is measured depending on the angles of the crystal lattice.

Adding noise to the images can be considered as a form of data augmentation. It can help the model generalize better by introducing more variability into the training data, making it more robust to variations in the input images. This also reduces the risk of overfitting the model to your training data.

Sorry for the delay in response. When monitoring sand in deep water subsea wells using an Acoustic Sand Detector (ASD), there are a few threshold values that can be used to indicate the presence of sand versus fluid flow. However, it's important to note that these thresholds may vary depending on the specific well conditions and the type of ASD being used.

Generally, an ASD will produce an output signal that represents the amplitude of the acoustic signal reflected from the wellbore. When sand is present in the fluid flow, it can cause a higher amplitude signal due to the reflection of acoustic waves from the sand particles. This signal can be analyzed to determine the amount and size distribution of sand particles present.

One threshold that can be used is the Sand Rate Threshold, which is the amplitude level at which the ASD output signal is considered to represent sand flow rather than fluid flow. This threshold value can vary depending on the specific ASD used, the well conditions, and the desired sensitivity of the sand monitoring system.

Another threshold that can be used is the Sand Alarm Threshold, which is a higher amplitude level at which an alarm signal is triggered to alert operators of high sand production rates. This threshold value is typically set based on the maximum acceptable sand production rate for the well, and can also vary depending on the specific well conditions and ASD being used.

It's important to note that these threshold values are not fixed and may need to be adjusted over time as the well conditions change. Additionally, it's important to have a good understanding of the specific ASD being used and its limitations to accurately interpret the output signals and make informed decisions about sand production rates in deep water subsea wells.

Typically, the 488/8 filter is used for FSC or SSC

There are various methods that have been used to create lie detectors using machine learning. One of the common approaches is based on physiological signals such as heart rate, blood pressure, respiration rate, skin conductance, and facial expressions. These signals are known to change when a person is lying or under stress. Machine learning algorithms can be trained on these physiological signals to detect patterns or changes that are indicative of lying.

Did the VWD work before on the SAME EXACT SYSTEM ? If so, then manually configure it. Delete the VWD module from the software configuration, then re-boot computer. After refresh, add the correct module back to the existing configuration screen and re-check.

If you obtained this module from someone or somewhere else and installed it into your system recently (and have not previously verified that the VWD is working properly), then there is a long list of possibilities to check. *One item worth checking BEFORE you use the VWD is check the current firmware versions installed on the module. The firwmare on the module must be compatible with both the CDS and the OTHER HPLC modules in the stack configuration. **Agilent provides all of the various firmware compatibility charts and files free of charge on their websites for download.

It is better to to communicate service engineer.

It depends on several things, we have done (single) scans of up to 10mm in size. With stitching (automatically moving the stage and make many scans), you can go much larger. A problem with the huge scans is the significant spatial distortions, particularly the trapezium distortion. Also, the pattern center shift correction needs to be properly calibrated for these large scans, to avoid misindexing at the edges.

"Reference" will be the background signal generated from light passing through your mobile phase solution. "Sample" will be the signal generated from well, the "sample" in the flow cell. These two values allow us to generate ONE final signal, the output signal which is what is normally recorded.

Muhammad Usman Hadi, I appreciate the response you gave. Yes, I'm aware of it. Actually, I'm interested in the equation (attached as an image). For example, what information do we gain if we change the parameter (N-K+1) in the equation (for ZF) to N (for MRC)? Second, how can we draw the asymptote from the equation when standard BER vs. SNIR commands are typically used in MATLAB simulations even for BER calculations with imperfect channel state information and equations (such as the one in the image for an imperfect channel) are not simulated for BER?

Hi there,

without knowing the details of your simulation I will say that this is a deep penetration problem. Meaning that the strong attenuation does not let many photons to reach your tallies. In fact, this is the reason why the tally uncertainty increases with distance. Related to that, MCNPX does not account for background "noise" or radiation; everything has to be modeled. If you search for "variation reduction" techniques you will get some ideas how to decrease the uncertainties (meaning weight windows, source biasing, importances). As a first step, you should look at the F5 tallies and the "flux-to-dose" conversion factors, included in MCNP. The latter will give you a more meaningful dose calculation for use in radiation protection. I hope this helps.

Good luck,

dimitris

Thank you Gerhard Martens ,but I already found this link on internet, this is only the first 9 pages.

I already contacted the manufacture, with no success, they only want to sell a new one...

The negative peak might arise from the contamination of your carrier gas. Try to use pure helium as your carrier gas.

Victor Alexandrovich Nikolaev thank you very much. This information was very helpful.

It is difficult to me

Gerhard Martens and sir, thank you for your valuable answer.

1) Gerhard Martens sir, I am not worrying about the plagairism of my work. My concern was about something else. Yes, we write multiple papers on the same research topic.

2) Yes sir, I know preprint does not have any value and significance. I just wanted to clear my query.

My concern (query) : I had written a paper (without any mathematics) which is currently under review. Its preprint is already available online. If somehow my paper gets rejected and I dont want to send the same paper to some other journal but want to add few more things like mathematical modeling and few more results and changing its title. Will it create a problem because almost 85% of the paper will match with the preprint available? I hope I am able to put my query in the best possible way. It means I will add few more things in that preprint before submitting it to some other journal. Can I do it or I can not change anything in that preprint?

Frank Lloyd

No special clinical need or product measurement.

Thought it could have been a blank control in some metabolic intervention experiments.

There are no data on insulin levels in indigenous mice population within their normal food environment, rather than WT one produced in the lab.

Reason: similar comparison can be projected between two human populations.

Hi Cruz.

Check this out:

I have solved my negative peaks problem regulating the valve.

This is a random emission.it does not have an alpha emission.

The technique described in this work can be used to interrogate such FBGs. All depends on the bandwidth of each peak and the separation between them.

Regards

A more sophisticated way to obtain isolates the scattering contributions is to analyze the trajectory of an MD simulation that most effectively captures the dynamics of your material system.

Once you can come up with an MD model that does so, you can computationally carry out the XPCS and extract an approximate signal. Here is a paper I've recently written to address the same:

The thin window (e.g. Be) and the electrical contact are different and separate.

The role of the window is to protect the Ge crystal from the atmosphere. It is a part of the wall of the protective chamber around the detector. There is no contact between the window and the crystal, as written by Gerhard Mertens.

The dead layer is a layer of doped Ge that plays the role of an electrode and is not able to detect radiation, but contributes to the filtration of soft X-rays.

Hi Sławomir,

If you email direct at greg.cawthray@uwa.edu.au i may be able to assist.

Regards

Greg

These three articles will help you find the answer

The bigger problem is perhaps the high price for the reference substance spheroidenone. Among others 10mg offered by Toronto Research Chemicals may become the best choice. You can test the purity the same time you prepare for your concentration-response correlation curve. The mass spectrum in the attached file has been made by GC-MS analysis. Isn't it to prefer before struggling with HPLC-MS?? It depends of course on your application and type of sample.

The Kerr rotation is measured through reflection, the Faraday effect through transmission. There are ``tricks" to enhance the signal, but the former is a surface effect, so the angle of rotation is independent of the thickness of the sample, the latter is a volume effect, so the angle is proportional to the thickness of the sample. This is part of any course in electromagntism.

See

Hi Celia Diaz Pines you are correct. Basically AFDD has a controller which senses the harmonics to detect the presence of arcs. When arc is detected the controller send command to trip. Such controllers can be designed for DC side as well, by studying the nature of DC arcs and feeding this info in the controller circuit.

GetGlobalTime will provide the amount of time elapsed from the beginning of the simulation. For time of flight, you may need to compute the difference in time between two events. You should thus have at least 2 detectors that are operating in coincidence.

I know of a Chemist that is here in Ipoh, Perak, Malaysia.

I'm to go see him about a sample I think is contaminated.

I need to know what is what of it & take a sample to him for test and leave the sample with him to tell me after he has tested it.