Performance evaluation of the Scent Transfer Unit (STU-100) for organic compound collection and release

The Scent Transfer Unit (STU-100) is a portable vacuum that uses airflow through a sterile gauze pad to capture a volatiles profile over evidentiary items for subsequent canine presentation to assist law enforcement personnel. This device was evaluated to determine its ability to trap and release organic compounds at ambient temperature under controlled laboratory conditions. Gas chromatography-mass spectrometry (GC-MS) analyses using a five-component volatiles mixture in methanol injected directly into a capture pad indicated that compound release could be detected initially and 3 days after the time of collection. Additionally, 15 compounds of a 39-component toxic organic gaseous mixture (10-1000 parts per billion by volume [p.p.b.(v)]) were trapped, released, and detected in the headspace of a volatiles capture pad after being exposed to this mixture using the STU-100 with analysis via GC-MS. Component release efficiencies at ambient temperature varied with the analyte; however, typical values of c. 10% were obtained. Desorption at elevated temperatures of reported human odor/scent chemicals and colognes trapped by the STU-100 pads was measured and indicated that the STU-100 has a significant trapping efficiency at ambient temperature. Multivariate statistical analysis of subsequent mass spectral patterns was also performed.     

Tetrahydrocannabinols in hair of hashish smokers

The study investigates the presence of tetrahydrocannabinols in the head hair and the pubic and axillary hair. The hair samples were obtained from hashish smokers. The concentrations were determined by radioimmunoassay and reflect total tetrahydrocannabinols and metabolites. The values found ranged from 0.4 ng/mg hair up to 3.8 ng/mg hair. The presence of the drug in the hair samples was also demonstrated by GC/MS.     

高校“音乐欣赏”选修课开设的几个问题

在高校教学过程中,选修课日益成为一道亮丽的风景,如何开设选修课以发挥其最大的教学功能,这是教育工作者普遍关注的问题.高校"音乐欣赏"选修课的开设一要明确教学目的,二要突破定向思维,三要设计课堂形式,四要增强师生交流.     

Mara Salvatrucha: The Most Dangerous Street Gang in the Americas?

Mara Salvatrucha (MS‐13), founded in 1980s Los Angeles by Salvadoran immigrant youth, is today one of the largest street gangs in North and Central America. In recent years the group has acquired a reputation for extreme brutality and has ostensibly mutated into a fast‐expanding, transnational organized crime network with possible ties to international terrorists. Drawing on key concepts in gang research and multiple methodological tools, this article seeks to sharpen understanding of MS‐13's structure and activities. While the group is active in many countries, it is transnational only in a symbolic manner, not in its configuration or span of authority. Impelled largely by Central American gang‐suppression policies, MS‐13 has evolved from a traditional street gang into a group with organized crime characteristics, but it remains a social phenomenon rooted in urban marginality. Ultimately, a more nuanced picture of Mara Salvatrucha can inform the search for more effective gang policies.     

Suicide by multiple blunt head traumatisation using a stone

Apart from collisions with road or rail vehicles and falls from height, self inflicted blunt force is a rare suicide method and mainly seen in psychiatric patients. The paper presents a rare case of suicide by active blunt force. A 68-year-old man committed suicide by repeatedly hitting his head with a stone. He sustained a craniocerebral trauma and finally died from hypothermia due to the low outdoor temperature. According to the relatives, the man was not diagnosed with a mental disorder or suicidal tendencies. Uncommon manners of self-harm are challenging for those involved in the investigation, and a differentiation between suicide, accident and homicide can only be made in synopsis of all findings.