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排序方式: 共有154条查询结果,搜索用时 31 毫秒
31.
Identification of colorants in pigmented pen inks by laser desorption mass spectrometry 总被引:1,自引:0,他引:1
Pigments are rapidly replacing dyes as colorants in pen and printer inks, due to their superior colors and stability. Unfortunately, tools commonly used in questioned document examination for analyzing pen inks, such as TLC, cannot be used for the analysis of insoluble pigments on paper. Laser desorption mass spectrometry is demonstrated here as a tool for analyzing pigment-based pen inks. A pulsed nitrogen laser can be focused onto a pen stroke from a pigmented ink pen on paper, and positive and negative ions representative of the pigment can be generated for subsequent mass spectrometric analysis. Targeted pens for this work were a set of Uni-ball 207 pigmented ink pens containing blue, light blue, orange, green, violet, red, pink, and black inks. Copper phthalocyanine was identified as the pigment used to make both blue inks. A mixture of halogenated copper phthalocyanines were identified in the green ink. Unexpectedly, the pink ink was found to contain a red pigment, Pigment Red 12, treated with a mixture of water-soluble dyes. Each sample yielded ions representative of the pigments present. 相似文献
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The electrostatic process for imaging indentations on documents using the ESDA device is investigated under controlled experimental settings. An in-house modified commercial xerographic developer housing is used to control the uniformity and volume of toner deposition, allowing for reproducible image development. Along with this novel development tool, an electrostatic voltmeter and fixed environmental conditions facilitate an optimization process. Sample documents are preconditioned in a humidity cabinet with microprocessor control, and the significant benefit of humidification above 70% RH on image quality is verified. Improving on the subjective methods of previous studies, image quality analysis is carried out in an objective and reproducible manner using the PIAS-II. For the seven commercial paper types tested, the optimum ESDA operating point is found to be at an electric potential near -400V at the Mylar surface; however, for most paper types, the optimum operating regime is found to be quite broad, spanning relatively small electric potentials between -200 and -550V. At -400V, the film right above an indented area generally carries a voltage which is 30-50V less negative than the non-indented background. In contrast with Seward's findings [G.H. Seward, Model for electrostatic imaging of forensic evidence via discharge through Mylar-paper path, J. Appl. Phys. 83 (3) (1998) 1450-1456; G.H. Seward, Practical implications of the charge transport model for electrostatic detection apparatus (ESDA), J. Forensic Sci. 44 (4) (1999) 832-836], a period of charge decay before image development is not required when operating in this optimal regime. A brief investigation of the role played by paper-to-paper friction during the indentation process is conducted using our optimized development method. 相似文献
33.
Steven Towler BS Marta Concheiro PhD Sue Pearring MS Luke N. Rodda PhD 《Journal of forensic sciences》2021,66(1):375-382
Performing point‐of‐care urine drug screen testing at autopsy by a forensic pathologist may provide an early indication of the presence of analytes of interest during autopsy. An evaluation for the screening of 14 classes of common drugs of abuse in postmortem urine by the point‐of‐care screening device, Alere iCup DX 14, is presented. One hundred ninety postmortem urine samples were screened with the iCup occurring at autopsy by the forensic pathologist. Positive and negative results obtained from the screening kit were evaluated against confirmatory test results obtained using routine forensic toxicology analyses that employed LC‐MS/MS and GC‐MS to detect a combination of over 85 common drugs of abuse and medications. Sensitivity for each respective iCup drug class ranged from 66% (buprenorphine) to 100% (methadone, tricyclic antidepressants). Specificity for each respective iCup drug class ranged from 89% (benzodiazepines) to 100% (amphetamines, barbiturates, buprenorphine, 3,4‐methylenedioxymethamphetamine, methadone). Positive predictive values ranged from 44% (benzodiazepines) to 100% (amphetamines, barbiturates, buprenorphine, methylenedioxymethamphetamine, methadone), while negative predictive values ranged from 96% (methamphetamine) to 100% (barbiturates, methadone, tricyclic antidepressants). A high false‐positive rate was yielded by the benzodiazepine class. The lack of fentanyl screening in the point‐of‐care device is a significant limitation considering its prolific prevalence in forensic casework. The results obtained in the study should be acknowledged when considering the use of the Alere iCup DX 14 in the context of postmortem casework to help indicate potential drug use contemporaneously with autopsy and when requiring such preliminary results prior to the release of a final forensic toxicology report. 相似文献
34.
Luke Fowler 《Public administration》2020,98(3):713-729
In managing complex policy problems in the federal system, state and local governments are organized into different arrangements for translating policy goals into policy outcomes. Air quality management is used as a test case to understand these variations and their impact on policy outcomes. With data from Clean Air Act implementation plans and a survey of state and local air quality managers, five separate institutional designs are identified: (1) central agencies; (2) top-down; (3) donor–recipient; (4) regional agencies; and (5) emergent governance. Findings indicate that some arrangements (donor–recipient and emergent governance) result in notably better air quality than others (central agencies, top-down). Specifically, when designed to allow bargaining between state and local officials, intergovernmental management is still the most effective approach to complex policy problems; but, in absence of this, conventional federalism arrangements are less effective than public agencies self-organizing around shared policy goals. 相似文献
35.
Sudden cardiac death during exercise in a weight lifter using anabolic androgenic steroids: pathological and toxicological findings 总被引:1,自引:0,他引:1
A 21-year-old, previously healthy weight lifter collapsed during a bench press workout. He had taken anabolic androgenic steroids parenterally for the previous several months. Pertinent autopsy findings included marked cardiac and renal hypertrophy and hepatosplenomegaly, with regional myocardial fibrosis and focal myocardial necrosis. Nandrolone (19-nor-testosterone) metabolites were identified in postmortem urine. The possible etiologies of the cardiac findings are discussed. 相似文献
36.
The Theological Underpinnings of Australia's Constitutional Separation of Church and State Provision
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Luke Beck 《澳大利亚政治与历史杂志》2018,64(1):1-17
The Australian Constitution contains two provisions concerning religion: a reference to “Almighty God” in the preamble and a provision denying the Federal Parliament power to legislate in respect of religion. The inclusion of those two provisions by the National Australasian Convention, which met from 1897 to 1898 to draft the Australian Constitution, was in large measure a result of political campaigns undertaken by competing religious groups. The first group, the Councils of Churches in each colony representing the main Protestant denominations, agitated for a constitutional “recognition” of God. The second group, the Seventh Day Adventists, campaigned against any constitutional recognition of God and for the inclusion of a provision limiting the Federal Government's power in respect of religion. The Adventists held fears that constitutional “recognition” of God would empower the federal parliament to pass nation‐wide Sunday observance laws. This article explores the theological and legal thinking of the Seventh Day Adventists to explain how they came to believe what, on a strict legal analysis, was highly implausible. 相似文献
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