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11.
Georgia W. Hodges Deborah Tippins J. Steve Oliver 《School science and mathematics》2013,113(6):263-274
Science teacher retention, attrition, and migration continue to perplex educational scholars, political entities, as well as the general public. This study utilized an interpretive methodological design to generate assertions regarding career choice made by highly qualified science teachers in the deep, rural South through analysis of documents, interviews, focus groups, and observation. Generally considered “difficult to staff” because of location, socioeconomics, and demographics, Wilson County High School is an exemplar in science teacher retention and student achievement. Findings presented include how the science department at Wilson County improved student learning outcomes as well as the reasons why two of the highly qualified science teachers at this school were considering leaving the profession they love. 相似文献
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Dr. Shaoguang Zhang Dr. Peng Cui Tianchang Liu Qiuran Wang Thomas J. Longo Laura M. Thierer Dr. Brian C. Manor Dr. Michael R. Gau Dr. Patrick J. Carroll Prof. Dr. Georgia C. Papaefthymiou Prof. Dr. Neil C. Tomson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15327-15331
Despite their connection to ammonia synthesis, little is known about the ability of iron-bound, bridging nitrides to form N−H bonds. Herein we report a linear diiron bridging nitride complex supported by a redox-active macrocycle. The unique ability of the ligand scaffold to adapt to the geometric preference of the bridging species was found to facilitate the formation of N−H bonds via proton-coupled electron transfer to generate a μ-amide product. The structurally analogous μ-silyl- and μ-borylamide complexes were shown to form from the net insertion of the nitride into the E−H bonds (E=B, Si). Protonation of the parent bridging amide produced ammonia in high yield, and treatment of the nitride with PhSH was found to liberate NH3 in high yield through a reaction that engages the redox-activity of the ligand during PCET. 相似文献
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Parks Conor D. Gaieb Zied Chiu Michael Yang Huanwang Shao Chenghua Walters W. Patrick Jansen Johanna M. McGaughey Georgia Lewis Richard A. Bembenek Scott D. Ameriks Michael K. Mirzadegan Tara Burley Stephen K. Amaro Rommie E. Gilson Michael K. 《Journal of computer-aided molecular design》2020,34(2):99-119
Journal of Computer-Aided Molecular Design - The Drug Design Data Resource (D3R) aims to identify best practice methods for computer aided drug design through blinded ligand pose prediction and... 相似文献
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Argyro G. Fragkaki Georgia Petropoulou Ioanna Athanasiadou Polyxeni Kiousi Nassia Kioukia‐Fougia Helen Archontaki Evangelos Bakeas Yiannis S. Angelis 《Journal of separation science》2020,43(11):2154-2161
Anabolic androgenic steroids are widely abused substances in sports doping. Their detection present limitations regarding the use of soft ion sources such as electrospray or atmospheric pressure chemical ionization by liquid chromatography–tandem mass spectrometry. In the current study, a novel derivatization method was developed for the ionization enhancement of selected anabolic androgenic steroids. The proposed method aims at the introduction of an easily ionizable moiety into the steroid molecule by converting the hydroxyl groups into imidazole carbamates using 1,1′‐carbonyldiimidazole as derivatization reagent. The proposed method was applied to water and urine samples spiked with exogenous anabolic androgenic steroids in various concentration levels. Steroid imidazole carbamate derivatives have shown intensive [M+H]+ signals under electrospray ionization and common fragmentation patterns in tandem mass spectrometry mode with [M‐CO2+H]+ and [M‐ΙmCO2+H]+ as major ions with low collision energy. The obtained results showed that the majority of steroids were detectable at concentrations equal or lower to their minimum required performance level according to the World Anti‐Doping Agency technical document. The proposed method is sensitive with a preparation procedure that could be easily applied to the analysis of doping control samples. 相似文献
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A New Approach for the Photosynthetic Antenna–Reaction Center Complex with a Model Organized Around an s‐Triazine Linker 下载免费PDF全文
Susanne Kuhri Dr. Georgios Charalambidis Prof. Panagiotis A. Angaridis Prof. Theodore Lazarides Dr. Georgia Pagona Dr. Nikos Tagmatarchis Prof. Dr. Athanassios G. Coutsolelos Prof. Dr. Dirk M. Guldi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):2049-2057
Two new artificial mimics of the photosynthetic antenna‐reaction center complex have been designed and synthesized (BDP‐H2P‐C60 and BDP‐ZnP‐C60). The resulting electron‐donor/acceptor conjugates contain a porphyrin (either in its free‐base form (H2P) or as Zn‐metalated complex (ZnP)), a boron dipyrrin (BDP), and a fulleropyrrolidine possessing, as substituent of the pyrrolidine nitrogen, an ethylene glycol chain terminating in an amino group C60‐X‐NH2 (X=spacer). In both cases, the three different components were connected by s‐triazine through stepwise substitution reactions of cyanuric chloride. In addition to the facile synthesis, the star‐type arrangement of the three photo‐ and redox‐active components around the central s‐triazine unit permits direct interaction between one another, in contrast to reported examples in which the three components are arranged in a linear fashion. The energy‐ and electron‐transfer properties of the resulting electron‐donor/acceptor conjugates were investigated by using UV/Vis absorption and emission spectroscopy, cyclic voltammetry, and femtosecond transient absorption spectroscopy. Comparison of the absorption spectra and cyclic voltammograms of BDP‐H2P‐C60 and BDP‐ZnP‐C60 with those of BDP‐H2P, BDP‐ZnP and BDP‐C60, which were used as references, showed that the spectroscopic and electrochemical properties of the individual constituents are basically retained, although some appreciable shifts in terms of absorption indicate some interactions in the ground state. Fluorescence lifetime measurements and transient absorption experiments helped to elucidate the antenna function of BDP, which upon selective excitation undergoes a rapid and efficient energy transfer from BDP to H2P or ZnP. This is then followed by an electron transfer to C60, yielding the formation of the singlet charge‐separated states, namely BDP‐H2P .+‐ C60 .? and BDP‐ZnP .+‐ C60 . ?. As such, the sequence of energy transfer and electron transfer in the present models mimics the events of natural photosynthesis. 相似文献
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Walks on the representation graph \({\mathcal{R}_{\mathsf{V}}}\)(G) determined by a group G and a G-module V are related to the centralizer algebras of the action of G on the tensor powers \({\mathsf{V}^{\otimes k}}\) via Schur-Weyl duality. This paper explores that connection when the group is \({\mathbb{Z}^{n}_{2}}\) and the module V is chosen so the representation graph is the n-cube. We describe a basis for the centralizer algebras in terms of labeled partition diagrams. We obtain an expression for the number of walks by counting certain partitions and determine the exponential generating functions for the number of walks. 相似文献
20.
Michael V. Turturro Daniela María Vélez Rendón Fouad Teymour Georgia Papavasiliou 《大分子反应工程》2013,7(2):107-115
Poly(ethylene glycol) diacrylate (PEGDA) hydrogels are extensively used as scaffolds in tissue engineering. The ability to spatially control hydrogel properties is critical for designing scaffolds that direct cell behavior and tissue regeneration. To this end, we have recently developed a polymerization technique, perfusion‐based frontal photopolymerization, to generate tunable gradients in PEG hydrogels. This study explores the effects of polymerization conditions on the velocity of the propagating front and its influence on gradients in hydrogel swelling. Alterations in photoinitiator perfusion rate result in the largest variations in frontal velocity and in the magnitude of the swelling gradient among all polymerization conditions investigated.