Fire accelerant classification from GC-MS data of suspected arson cases using machine-learning models.

Using a practical GC-MS dataset containing approximately 4000 suspected arson cases, three machine-learning based classification models were developed and their performances were evaluated. All models trained for classifying the data from fire residue into six categories; no fire accelerants detected or else one of fire accelerants was used within gasoline, kerosene, diesel, solvents, or candle. The classification accuracies of the random forest, supporting vector machine, and convolutional neural network model were 0.

Tracing the geographical origin of bottled water collected in South Korea via isotopic and elemental analyses.

Rationale: The production of bottled water requires a forensic discriminant technique that enables the identification of the brands or accidents caused by intended contaminants. The bottled water poisoning crimes have drawn much attention, and such crimes may recur in the future. The water is colorless and odorless, and thus it is difficult to detect contaminated water through visual observation.

H-NMR with Multivariate Analysis for Automobile Lubricant Comparison.

Identification of suspected automobile-related lubricants could provide valuable information in forensic cases. We examined that automobile lubricants might exhibit the chemometric characteristics to their individual usages. To compare the degree of clustering in the plots, we co-plotted general industrial oils that were highly dissimilar with automobile lubricants in additive compositions.

Polymerase recognition of 2-thio-iso-guanine·5-methyl-4-pyrimidinone (iGs·P)--A new DD/AA base pair.

Polymerase specificity is reported for a previously unknown base pair with a non-standard DD/AA hydrogen bonding pattern: 2-thio-iso-guanine·5-methyl-4-pyrimidinone. Our findings suggest that atomic substitution may provide a solution for low fidelity previously associated with enzymatic copying of iso-guanine.

Classification and individualization of used engine oils using elemental composition and discriminant analysis.

The six most common commercial automotive gasoline and diesel engine oils in the Republic of Korea, ZIC A, ZIC XQ RV/SUV, Kixx G1, Kixx RV, and the brand name products HD Premium gasoline and HD Premium diesel, were randomly used in nineteen different vehicles. Samples of seventy-six used engine oils, which were withdrawn from the sumps of those vehicles at different intervals, were analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES), and statistically compared. Two data analysis strategies were used to interpret and understand the elemental profiles in the multi-dimensional data.

1H NMR spectroscopic identification of a glue sniffing biomarker.

Organic solvent abuse typically involves sniffing organic solvents to experience the mind-altering conditions they induce. In Republic of Korea, organic solvent abuse is a serious social problem, especially among teenagers. Several studies have addressed the effects of organic solvent abuse on mind and body, but there are no simple methods by which such abuse can be positively identified.