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521.
522.
Kristina Clemons B.S. Rachel Wiley B.S. Kristin Waverka B.A. James Fox M.Sc. Eric Dziekonski B.S. Guido F. Verbeck Ph.D. 《Journal of forensic sciences》2013,58(4):875-880
Here, we present a method of extracting drug residues from fingerprints via Direct Analyte‐Probed Nanoextraction coupled to nanospray ionization–mass spectrometry (DAPNe‐NSI‐MS). This instrumental technique provides higher selectivity and lower detection limits over current methods, greatly reducing sample preparation, and does not compromise the integrity of latent fingerprints. This coupled to Raman microscopy is an advantageous supplement for location and identification of trace particles. DAPNe uses a nanomanipulator for extraction and differing microscopies for localization of chemicals of interest. A capillary tip with solvent of choice is placed in a nanopositioner. The surface to be analyzed is placed under a microscope, and a particle of interest is located. Using a pressure injector, the solvent is injected onto the surface where it dissolves the analyte, and then extracted back into the capillary tip. The solution is then directly analyzed via NSI‐MS. Analyses of caffeine, cocaine, crystal methamphetamine, and ecstasy have been performed successfully. 相似文献
523.
Rachel Baker Elizabeth Friedmann Michal Kurlaender 《Journal of policy analysis and management》2023,42(2):488-524
The transfer between two-year and four-year colleges is a critical path to baccalaureate attainment. Yet students face a number of barriers in transfer pathways, including a lack of coherent coordination and articulation between their community colleges and four-year institutions, resulting in excess units and increased time to degree. In this paper we evaluate the impact of California's Student Transfer Achievement Reform Act, which aimed to create a more seamless pathway between the California Community Colleges and the California State University. We investigate whether the reform effort met its intended goal of improving baccalaureate receipt, and greater efficiency in earning these degrees, among community college transfer students. We tease out plausibly causal effects of the policy by leveraging the exogenous variation in the timing of the implementation of the reform in different campuses and fields of study. We find an overall positive effect on bachelor's degree attainment. This increase is driven entirely by increased transfer rather than an increased probability of earning a BA/BS conditional on transfer. We find only suggestive evidence that the policy led to greater efficiency (i.e., fewer units at graduation) in BA/BS receipt for transfer students. These findings are broadly consistent across student subgroups. 相似文献