Spectroscopic And Computational Studies Of The Laser Photolysis Of Matrix Isolated 1,2-dibromoethanes: Formation And Fate Of The Bromoethyl Radicals

We report experimental and computational studies of the photolysis of atmospherically important 1,2-dibromoethanes (1,2-C(2)X(4)Br(2); X = H, F) in Ar matrixes at 5 K. Using the pulsed deposition method, we find that significant conformational relaxation occurs for 1,2-C(2)H(4)Br(2) (EDB; observed anti/gauche ratio =30:1) but not for 1,2-C(2)F(4)Br(2) (TFEDB; anti/gauche = 3:1), which is traced to a larger barrier to rotation about the C-C bond in the latter. Laser photolysis of matrix-isolated EDB at 220 nm reveals the growth of infrared bands assigned to the gauche conformer and C(2)H(4)-Br(2) charge transfer complex (both as major products), and the C(2)H(4)Br radical and C(2)H(3)Br-HBr complex as minor (trace) products. The presence of the C(2)H(4)-Br(2) complex is confirmed in the UV/visible spectrum, which shows an intense charge transfer band at 237 nm that grows in intensity upon annealing. In contrast to previous reports, our experimental and computational results do not support a bridged structure for the C(2)H(4)Br radical in either the gas phase or matrix environments. We also report on the laser photolysis of matrix-isolated TFEDB at 220 nm. Here, the dominant photoproducts are the anti and gauche conformers of the C(2)F(4)Br radical, the vibrational and electronic spectra of which are characterized here for the first time. The increase in yield of radical for TFEDB vs EDB is consistent with the stronger C-Br bond in the fluoro-substituted radical species. The photochemistry of the C(2)F(4)Br radical following excitation at 266 nm was investigated and found to lead C-Br bond cleavage and formation of C(2)F(4). The implications of this work for the atmospheric and condensed phase photochemistry of the alkyl halides is emphasized

Sonographic Findings of Pectoralis Major Tears With Surgical, Clinical, and Magnetic Resonance Imaging Correlation in 6 Patients

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135465/1/jum200524125.pd

Characterization of Iso -Cf2 I2 in Frequency and Ultrafast Time Domains

The photolysis of diiododifluoromethane (CF2 I2) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF2 I2:Ar samples (1:5000) held at ∼8 K yielded iso -CF2 I2 (F2 C-I-I), a metastable isomer of CF2 I2, characterized here for the first time. The infrared (IR) spectra of this isomer were recorded in matrix experiments, and the derived positions of the C-F stretching modes are in very good agreement with the predictions of high level ab initio calculations, which show that the iso -form is a minimum on the CF2 I2 ground state potential energy surface. The formation of this isomer following 350 nm excitation of CF2 I 2 in room temperature CCl4 solutions was monitored through its intense C-F stretching mode by means of ultrafast time-resolved IR absorption. Together, matrix isolation and ultrafast IR absorption experiments suggest that the formation of iso -CF2 I2 occurs via recombination of CF2 I radical and I atom. Ultrafast IR experiments detect a delayed rise of iso -CF2 I-I absorption, placing an upper limit of 400 fs for the C-I bond dissociation and primary geminate recombination processes. The product absorption spectrum recorded 1 ns after 350 nm excitation of CF2 I2 in solution is virtually identical to the visible absorption spectrum of i so -CF2 I2 trapped in matrix isolation experiments [with subtracted I2 (X) absorption]. The formation of this isomer in solution at room temperature has direct dynamic implications for the ultrafast production of molecular iodine from electronically excited CF 2 I2. © 2010 American Institute of Physics

Avaliação do sistema reprodutivo em acessos de bacabinha (Oenocarpus mapora Karsten.) em Belém-PA.

A bacabinha é uma fruteira nativa da Amazônia com potencial econômico para frutos, sendo utilizados na obtenção de uma bebida conhecida por "bacaba ", mas tem sido pouco estudada. Neste trabalho, avaliou-se o sistema reprodutivo de acessos dessa palmeira existentes na Coleção de Germoplasma da Embrapa Amazônia Oriental, em Belém-PA. Foram escolhidos ao acaso, oito acessos procedentes de Abaetetuba-PA e duas plantas por acesso. Em cada planta foi marcada uma espata próxima a maturação para a aplicação de cinco testes reprodutivos, sendo destinadas três ráquilas para cada teste. As características avaliadas foram: flores fecundadas (FF), flores caídas (FC), flores abortadas (FA) e frutos colhidos (FRC), expressas em percentagens. As análises estatísticas foram feitas com base no modelo matemático inteiramente casualizado, em esquemafatorial8 x 5 com seis repetições. Os acessos, os testes reprodutivos e a interação acessos x testes diferiram entre si para todas as características avaliadas (P ::;0,01). Um acesso exibiu a maior média para flores caídas, enquanto outros três alcançaram as maiores médias para flores fecundadas e abortadas. Para a percentagem de frutos colhidos, quatro acessos se destacaram dos demais. Na agamospermia e na autopolinização natural foram registradas as maiores percentagens de flores caídas. O contrário ocorreu nos teste de polinização cruzada e aberta que tiveram as maiores médias de flores fecundadas e abortadas, e também de frutos colhidos. Com base nesses resultados pode-se concluir que todos os acessos são predominantemente alógamos

Malaria Parasite Invasion of the Mosquito Salivary Gland Requires Interaction between the Plasmodium TRAP and the Anopheles Saglin Proteins

SM1 is a twelve-amino-acid peptide that binds tightly to the Anopheles salivary gland and inhibits its invasion by Plasmodium sporozoites. By use of UV-crosslinking experiments between the peptide and its salivary gland target protein, we have identified the Anopheles salivary protein, saglin, as the receptor for SM1. Furthermore, by use of an anti-SM1 antibody, we have determined that the peptide is a mimotope of the Plasmodium sporozoite Thrombospondin Related Anonymous Protein (TRAP). TRAP binds to saglin with high specificity. Point mutations in TRAP's binding domain A abrogate binding, and binding is competed for by the SM1 peptide. Importantly, in vivo down-regulation of saglin expression results in strong inhibition of salivary gland invasion. Together, the results suggest that saglin/TRAP interaction is crucial for salivary gland invasion by Plasmodium sporozoites

Accelerating String Set Matching in FPGA Hardware for Bioinformatics Research

<p>Abstract</p> <p>Background</p> <p>This paper describes techniques for accelerating the performance of the string set matching problem with particular emphasis on applications in computational proteomics. The process of matching peptide sequences against a genome translated in six reading frames is part of a proteogenomic mapping pipeline that is used as a case-study. The Aho-Corasick algorithm is adapted for execution in field programmable gate array (FPGA) devices in a manner that optimizes space and performance. In this approach, the traditional Aho-Corasick finite state machine (FSM) is split into smaller FSMs, operating in parallel, each of which matches up to 20 peptides in the input translated genome. Each of the smaller FSMs is further divided into five simpler FSMs such that each simple FSM operates on a single bit position in the input (five bits are sufficient for representing all amino acids and special symbols in protein sequences).</p> <p>Results</p> <p>This bit-split organization of the Aho-Corasick implementation enables efficient utilization of the limited random access memory (RAM) resources available in typical FPGAs. The use of on-chip RAM as opposed to FPGA logic resources for FSM implementation also enables rapid reconfiguration of the FPGA without the place and routing delays associated with complex digital designs.</p> <p>Conclusion</p> <p>Experimental results show storage efficiencies of over 80% for several data sets. Furthermore, the FPGA implementation executing at 100 MHz is nearly 20 times faster than an implementation of the traditional Aho-Corasick algorithm executing on a 2.67 GHz workstation.</p