Analysis of the ex-vivo transformation of semen, saliva and urine as they dry out using ATR-FTIR spectroscopy and chemometric approach.

The ex-vivo biochemical changes of different body fluids also referred as aging of fluids are potential marker for the estimation of Time since deposition. Infrared spectroscopy has great potential to reveal the biochemical changes in these fluids as previously reported by several researchers. The present study is focused to analyze the spectral changes in the ATR-FTIR spectra of three body fluids, commonly encountered in violent crimes i.e., semen, saliva, and urine as they dry out. The whole analytical timeline is divided into relatively slow phase I due to the major contribution of water and faster Phase II due to significant evaporation of water. Two spectral regions i.e., 3200-3400 cm-1 and 1600-1000 cm-1 are the major contributors to the spectra of these fluids. Several peaks in the spectral region between 1600 and 1000 cm-1 showed highly significant regression equation with a higher coefficient of determination values in Phase II in contrary to the slow passing Phase I. Principal component and Partial Least Square Regression analysis are the two chemometric tool used to estimate the time since deposition of the aforesaid fluids as they dry out. Additionally, this study potentially estimates the time since deposition of an offense from the aging of the body fluids at the early stages after its occurrence as well as works as the precursor for further studies on an extended timeframe.

Forensic investigation of arson residue by infrared and Raman spectroscopy: From conventional to non-destructive techniques.

Arson can result in highly challenging and complicated crime scenes. Much physical evidence undergoes chemical degradation because of the destructive nature of fire, while accelerants either completely burn or evaporate, and may be present in traces within any of the decomposed materials. To identify the original material and the accelerant involved, it is necessary to use advanced analytical techniques. Gas chromatography, with different detectors, is one of the most frequently used instruments in fire debris and accelerant analysis. Among other instruments, capillary electrophoresis and laser-induced thermal desorption Fourier transform mass spectrometry are two major contributors. Vibrational spectroscopy, including infrared absorption and Raman scattering, is one of the major non-destructive tools for the analysis of evidence because of its advantages over other spectroscopic techniques. Most studies involving vibrational spectroscopy (i.e. infrared and Raman spectroscopy) have focused on the identification of commonly found household materials, while very few studies have considered the identification of ignitable liquids. This article reviews studies based on an analysis of fire debris and accelerants by vibrational spectroscopic techniques and considers the limitations and future perspectives of arson investigations in forensic science.

Effectiveness of single use over multiple use toothbrushes on negative oral microflora of plaque.

CONTEXT: Role of toothbrush in decreasing oral microflora. AIMS: To evaluate the effectiveness and compare the negative oral microbial flora of dental plaque after the use of a self-contaminated multiple use toothbrush and that of a single-use toothbrush. SETTINGS AND DESIGN: Sixty healthy individuals without any systemic conditions. METHODS AND MATERIALS: The study conducted with 60 participants who were free from any systemic or oral disease and without any adverse habits. In these participants, plaque samples were collected after 1 month use of a self-contaminated multiple use toothbrush. Each participant was given a set of 30 new toothbrushes and a toothpaste tube and instructed to use one toothbrush everyday and discard it after use. The plaque samples were collected on seven days interval and cultured on Mitis Salivarius agar. The colonies were identified and their count was recorded. STATISTICAL ANALYSIS USED: Student t test was applied. RESULTS: Streptococcus mutans, S. sanguis, S. milleri, and Candida were identified from the samples. A highly marked decrease in their numbers was found after the use of a single-use toothbrush over multiple use toothbrushes. CONCLUSIONS: As a self-contaminated multiple use toothbrushes can aid microorganisms to grow rapidly into the oral cavity, it may be preferable to change the toothbrush as frequently as possible.

Genetic data for PowerPlex 21™ autosomal and PowerPlex 23 Y-STR™ loci from population of the state of Uttar Pradesh, India.

In the present study, the statistical forensic parameters were evaluated for the loci present in PowerPlex 21 autosomal and PowerPlex 23 Y-STR multiplex systems in 168 unrelated individuals living in the state of Uttar Pradesh, India. The combined discrimination power (CPD) and combined exclusion power (CPE) was 1 and 0.999999 respectively for all 20 autosomal STR loci. Penta E showed the greatest (0.980) and CSF1PO showed the lowest (0.855) power of discrimination in the studied population. The haplotype diversity for 23 Y-STR loci was observed to be 0.999. The study also presents the first global report on polymorphism on D1S1656, D6S1043 and D12S391 autosomal STR loci in the Indian population. The resulting data revealed that these STR multiplex systems are highly polymorphic and can be used for forensic purposes.