Volume
22. Number 1
December 2023
Original Articles
Hsiao-Wen Huang, M.S.; Wei-Tun Chang, Ph.D.
Abstract¡G In order to improve the authentication effectiveness by
principal component analysis (PCA), 52 single malt Scotch whiskies, 31 blended
Scotch whiskies, and 3 adulterated Scotch whiskies were analyzed to select
appropriate fermentation congeners with gas chromatography-mass spectrometry
(GC-MS). After the evaluation process, six fermentation congeners, including
acetaldehyde, ethyl acetate, ethyl octanoate, 2-methyl propanol, 2-methyl
butanol, and 3-methyl butanol, were selected based on the total explained
variances results of PCA. Subsequently, the distribution fitting method
demonstrated that the data distribution of these six fermentation congeners more
suitably corresponded to the lognormal distribution for both authentic single
malt Scotch whiskies and authentic blended Scotch whiskies. Along with comparing
original data and log-transformed data of the integrated value of selected
fermentation congeners, PCA charts with log-transformed data were demonstrated
to express better exclusory authentication results for single malt Scotch
whiskies. For blended Scotch whiskies, both PCA and LDA, with log-transformed
data, can enhance the discrimination of adulterated samples. As a result, it was
verified that PCA with log-transformed data could effectively improve
the discriminating power in determining the authenticity of adulterated Scotch
whiskies.
Keywords: forensic science, authentication, adulterated Scotch whisky,
fermentation congeners, normality test, lognormal
distribution, principal component analysis (PCA), gas chromatography-mass
spectrometry (GC-MS)
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Influence of the Projectile Type on the Energy Density Examination of Airguns
Fu-Jen Chen, M.Sc.; Hsien-Hui Meng, Ph.D.
Abstract¡G Although airguns are generally thought of low-powered weapons, some of them are able to cause lethal injuries. A literature search yielded many reports of accidental, suicidal, and homicidal penetrating airgun injuries in eye and internal organs of human body. This revealed the potential danger of air weapons. Thus, airguns with kinetic energy above certain legal limits are legally regulated in some countries. In Taiwan, the legal power limit of airguns is 20 J/cm2 and the chronographic method is used to determine the projectile energy density (ED). In this study, one rifled air pistol was used to perform firing tests. The velocity and ED of sixteen types of Diabolo projectiles with varied nose shape and material composition, one ball-type lead projectile, and one Sheridan cylindrical lead projectile were determined and their variations were investigated. The experimental results indicated that ED values of six types of projectiles were above the Taiwanese legal power limit (20.24¡V21.66 J/cm2), while others were below it (16.94¡V19.94 J/cm2). Among them, the Diabolo round-nosed lead projectiles had the highest ED values. The results also demonstrated that the projectile velocity is inversely proportional to its mass (R2 = 0.9323), while projectile ED is influenced by its mass, geometric shape, and material composition. Thus, the legal status of an airgun is likely to be wrongly determined if unsuitable type of projectiles are used for ED examination. We suggest that the Diabolo round-nosed lead projectile is most suitable for the legal status determination of rifled airguns. And we expect the use of suitable type of projectiles will reduce false-negative results and strengthen the reliability and validity of ED examination of suspected illegal airguns.
Keywords: forensic science, firearms examination, airguns, energy density examination, projectile type, Diabolo
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Caitlyn Kresge, M.S.; Krystal Sears, Jared Baker, B.S ; Lindsey A. Welch, Ph.D ; Matthew Quinn, M.S.; Lawrence Quarino, Ph.D.
Abstract¡G While the combination of microcrystalline tests and Raman spectroscopy have been used in the detection and identification in forensic drug analysis, no such method has been attempted with materials commonly present in the inorganic portion of explosives. Many other techniques have been used in the analysis of components of explosives, but none are as rapid, require little preparation, reproducible, and require trace amounts as the method to be described. In this method, Raman microspectroscopy is paired with microcrystalline tests to identify seven cations (ammonium, barium, calcium, potassium, silver, sodium, and strontium), six anions (chlorate, nitrate, nitrite, oxalate, perchlorate, and tartrate) and urea commonly found in homemade explosives or improvised explosive devices, specifically, those found in fertilizers, fireworks, and pyrotechnics. Raman spectra were generated from microcrystals produced in aqueous test samples prepared with commercially available inorganic salts and reacted with three common reagents used to develop microcrystals: squaric acid, nitron, and chloroplatinic acid. The combination of microcrystal shape/ physical characteristics and Raman spectra used in this study serves as a useful model for the incorporation of this type of methodology for the identification of inorganic ions typically found in homemade explosives.
Keywords: microcrystalline tests, Raman microspectroscopy, inorganic ions, homemade explosives
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Influence of Ambient Temperature on the Legal Status Determination of Airguns
Fu-Jen Chen, M.Sc.; Hsien-Hui Meng, Ph.D.
Abstract¡G Airguns employ pressurized air or vapors of liquefied gases to discharge projectiles, and thus are usually considered to be harmless. However, some of them are capable of inflicting lethal injuries. Thus, a legal power limit of 20 J/cm2 is given to regulate the dangerous airguns in Taiwan. And the legal status of airguns is determined through muzzle energy density (ED) examination. The muzzle EDs of pneumatic and spring-piston airguns have been reported to be affected by ambient temperature. However, the influence of ambient temperature on the muzzle EDs of liquefied-gas airguns has not been investigated. In this study, a series of firing tests were conducted using one spring-piston, three pneumatic, and three liquefied-gas airguns to investigate the influence of temperature on their muzzle EDs. The results indicated that over an increase of 7 ¢XC in ambient temperature, the liquefied CO2 airgun obtained the most increase of muzzle ED, followed by the liquefied propane airguns and the pneumatic airguns, whereas the spring-piston airgun had the least increase of muzzle ED. The results of a t-test using a confidence level of 90% showed that the differences between the EDs obtained at different temperatures were statistically significant for all types of airguns tested. The interior ballistic fundamentals of the influence of ambient temperature on the muzzle EDs of different types of airguns are discussed in detail. The muzzle ED examination results of one experimental pneumatic airgun and one actual-case liquefied CO2 airgun verified that an airgun was probable to have muzzle EDs lower than the legal power limit at lower temperature while higher than the legal limit at higher temperature. This reveals that the ambient temperatures of forensic laboratories shall be carefully controlled to accurately determine the legal status of a suspicious airgun.
Keywords: forensic science, firearms examination, airguns, legal status, ambient temperature, muzzle energy density
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