The researchers from Vienna have also noted:
* “NIR spectra were acquired in the wavelength range of 1100-2300nm by means of a transflectance probe for measurements in liquid samples.”
* “For building of regression models a genetic algorithm has been applied for variable selection, and partial least-squares (PLS) regression for creation of linear models.”
* “A realistic estimation of the prediction performance of the models was obtained by a repeated double cross-validation (rdCV).”
* “Reduced data sets with only 15 variables showed improved prediction qualities, in comparison with models containing 235 variables, particularly for the determination of the ethanol concentration in distillation residues (stillages).”
* “The squared correlation coefficient, R(2), between the concentrations obtained by HPLC analysis and the concentrations derived from NIR data (using 15 selected wavelengths, test set samples) was 0.999 for ethanol in stillage, and 0.977 for glucose in mash.”
* “The standard deviation of prediction errors, SEP, obtained from test set samples was 0.6gL(-1) for ethanol (2% of the mean ethanol concentration), and 2.0gL(-1) for glucose (9.6% of the mean glucose concentration).”
5/29/09
5/21/09
Sample cell for hand-held impedance spectroscopy device
Disclosed herein is a sample cell for use in conjunction with an impedance spectroscopy analysis device having two electrodes extending therefrom. The sample cell is attachable to and detachable from the analysis device and includes a housing having an input port for receiving a fluid sample to be tested. The sample cell also includes two spaced apart parallel plates within the housing and in contact with the fluid sample, wherein when the sample cell is attached to the analysis device, each of the two electrodes contacts a respective one of the plates such that an excitation signal can be provided from the analysis device via the electrodes and the plates to excite the fluid sample, and a response signal indicative of the fluid sample can be communicated via the plates and the electrodes to the analysis device.
5/20/09
Portable forensic tool identified for human hair analysis
Analysis of human hair at a crime scene may be possible with a portable technique adapted by Queensland University of Technology researcher Sarina Brandes.
The technique, called Near Infrared Spectroscopy (NIRS), has the advantage of being readily available and Ms Brandes has demonstrated it could be used to analyse hair for forensic purposes.
A chemistry Masters researcher, Ms Brandes said this method was independent of analysis of DNA, which could break down quite quickly, especially at disaster scenes such as after a tsunami.
Her supervisor, Dr Serge Kokot, who has researched the forensic possibilities of human hair analysis for the past 12 years, said human hair could survive relatively harsh environments, where DNA couldn't.
"NIRS has been found to need only a few millimetres of a single hair for analysis, but until now, we have not had the ready capacity to apply this technology in harsh environments," Dr Kokot said.
"Ms Brandes' achievement is several fold: it opens the door for on-field measurements; it provides a method for analysis of hair after immersion in water, and it also has the advantage to readily differentiate a naturally coloured hair from that treated with a hair dye to give a similar colour."
Dr Kokot said Ms Brandes' technique could obtain the infrared profile from only a tiny part of a strand of hair and then interpret this profile using specialised mathematical methods to compare it with similar profiles collected from suitable reference hair samples.
"The results can be displayed in an easily understood diagram and/or the profiles can be rank-ordered and the position of the tested hair can be established relative to the reference samples," he said.
"In this manner, Sarina's technique can establish a person's gender, race and whether they had chemically treated their hair, as well as what the original hair colour was."
Dr Kokot said the use of Ms Brandes' research could help to identify victims of natural disasters, like tsunamis, where hair has been in water.
"Other useful spin-offs have been that Sarina's technique can also identify what type of water the hair was found in, like sea water, and how long the hair had been immersed in it," he said.
"Hair found at a crime scene could be matched against hair found in a comb of the victim which can be used as the reference sample, or it can be compared against hairs from suspects in a similar manner."
Dr Kokot said portable NIRS instruments were available and could be used at a crime or disaster scene.
The technique, called Near Infrared Spectroscopy (NIRS), has the advantage of being readily available and Ms Brandes has demonstrated it could be used to analyse hair for forensic purposes.
A chemistry Masters researcher, Ms Brandes said this method was independent of analysis of DNA, which could break down quite quickly, especially at disaster scenes such as after a tsunami.
Her supervisor, Dr Serge Kokot, who has researched the forensic possibilities of human hair analysis for the past 12 years, said human hair could survive relatively harsh environments, where DNA couldn't.
"NIRS has been found to need only a few millimetres of a single hair for analysis, but until now, we have not had the ready capacity to apply this technology in harsh environments," Dr Kokot said.
"Ms Brandes' achievement is several fold: it opens the door for on-field measurements; it provides a method for analysis of hair after immersion in water, and it also has the advantage to readily differentiate a naturally coloured hair from that treated with a hair dye to give a similar colour."
Dr Kokot said Ms Brandes' technique could obtain the infrared profile from only a tiny part of a strand of hair and then interpret this profile using specialised mathematical methods to compare it with similar profiles collected from suitable reference hair samples.
"The results can be displayed in an easily understood diagram and/or the profiles can be rank-ordered and the position of the tested hair can be established relative to the reference samples," he said.
"In this manner, Sarina's technique can establish a person's gender, race and whether they had chemically treated their hair, as well as what the original hair colour was."
Dr Kokot said the use of Ms Brandes' research could help to identify victims of natural disasters, like tsunamis, where hair has been in water.
"Other useful spin-offs have been that Sarina's technique can also identify what type of water the hair was found in, like sea water, and how long the hair had been immersed in it," he said.
"Hair found at a crime scene could be matched against hair found in a comb of the victim which can be used as the reference sample, or it can be compared against hairs from suspects in a similar manner."
Dr Kokot said portable NIRS instruments were available and could be used at a crime or disaster scene.
5/19/09
5/16/09
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