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801.
802.
803.
The matrix isolation technique with Fourier transform infrared detection has been applied to determine the products of gaseous radical reactions. The gas phase reactions were carried out in a discharge flow system and about 1% of the gas mixture was deposited onto a low temperature target through a pinhole. A differential pumping scheme was employed to maintain the pressure of the cryosystem below 10?5 torr while that of the flow system was kept at about 2 torr. Species including HO2 (from the H+O2 reaction), ClO2 (from the Cl+O2 reaction) and ClO (from the Cl+O3 reaction) have been produced in the gas phase and were successfully trapped in matrices and detected with an FTIR spectrometer. In addition, both HCl and HOCl have been detected as the reaction products from the gaseous ClO+HO3 reaction. The production of HCl from the ClO+HO2 reaction may have a significant impact on catalytic ozone destruction in the atmosphere. 相似文献
804.
Isolation of high-quality RNA from Dendrobium candidum is particularly difficult. D. candidum contains considerable amounts of polysaccharides that coprecipitate with RNA, which render RNA unsuitable for either cDNA synthesis and/or PCR amplification. In this paper, a rapid and efficient method was described for functional RNA isolation from the callus of D. candidum. The procedure included: (i) an extraction with phenol and isopropyl alcohol, to remove proteins and polyphenols; (ii) purifications by lithium chloride, pre-cooled (−20 °C) ethanol successively to remove polysaccharides. The method resulted in high-quality RNA suitable for DDRT-PCR and cDNA library analysis finally. 相似文献
805.
A low-cost and high-throughput benchtop cell sorter for isolating white blood cells from whole blood
The ability to isolate and purify white blood cells (WBCs) from mixed ensembles such as blood would benefit autologous cell-based therapeutics as well as diagnosis of WBC disorders. Current WBCs isolation methods have the limitations of low purity or requiring complex and expensive equipment. In addition, due to the overlap in size distribution between lymphocytes (i.e., a sub-population of WBCs) and red blood cells (RBCs), it is challenging to achieve isolation of entire WBCs populations. In this work, we developed an inertial microfluidics-based cell sorter, which enables size-based, high-throughput isolation, and enrichment of WBCs from RBC-lysed whole blood. Using the developed inertial microfluidic chip, the sorting resolution is sharpened within 2 μm, which achieved separation between 3 and 5 μm diameter particles. Thus, with the present cell sorter, a full population of WBCs can be isolated from RBC-lysed blood samples with recovery ratio of 92%, and merely 5% difference in the composition percentage of the three subpopulations of granulocytes, monocytes, and lymphocytes compared to the original sample. Furthermore, our cell sorter is designed to enable broad application of size-based inertial cell sorting by supplying a series of microchips with different sorting cutoff size. This strategy allows us to further enrich the lymphocytes population by twofold using another microchip with a cutoff size between 10 and 15 μm. With simplicity and efficiency, our cell sorter provides a powerful platform for isolating and sorting of WBCs and also envisions broad potential sorting applications for other cell types. 相似文献
806.
Dr. Thomas Lohmiller Dr. Sujan K. Sarkar Dr. Jörg Tatchen Dr. Stefan Henkel Dr. Tim Schleif Dr. Anton Savitsky Prof. Elsa Sanchez-Garcia Prof. Wolfram Sander 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(71):17873-17879
o-Tolylmethylene 1 is a metastable triplet carbene that rearranges to o-xylylene 2 even at temperatures as low as 2.7 K via [1,4] H atom tunneling. Electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopical techniques were used to identify two conformers of 1 (anti and syn) in noble gas matrices and in frozen organic solutions. Conformer-specific kinetic measurements revealed that the rate constants for the rearrangements of the anti and syn conformers of 1 are very similar. However, the orbital alignment in the syn conformer is less favorable for the hydrogen transfer reaction than the orbital configuration in the anti conformer. Our spectroscopic and quantum chemical investigations indicate that anti 1 and syn 1 rapidly interconvert via efficient quantum tunneling forming a rotational pre-equilibrium. The subsequent second tunneling reaction, the [1,4] H migration from anti 1 to 2 , is rate-limiting for the formation of 2 . We here present an efficient strategy for the study of such tunneling equilibria. 相似文献
807.
Spectroscopic and theoretical studies were carried out for O,O,O-trimethyl selenophosphate molecule. DFT structural and vibrational calculations were performed at 6-311++G∗∗ level. Ar/matrix-FTIR spectra were recorded. A coexistence of different conformers with C3 and C1 symmetries was detected at different temperatures. Spectral evidence of a lower energy Cs conformer was found. These conclusions are consistent with the results from DFT calculations. A tentative assignment of the features observed in the Ar/matrix-FTIR spectra is proposed. 相似文献
808.
Artur Mardyukov Elsa Sanchez‐Garcia Dr. Rachel Crespo‐Otero Wolfram Sander Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(26):4804-4807
That's radical! A photochemical reaction between the phenyl radical and water results in the abstraction of a hydrogen atom from water and the formation of a hydroxyl radical. The hydroxyl radical forms an OH???π hydrogen bond with benzene (see picture) and does not react with benzene thermally under the conditions of matrix isolation.
809.
E. N. Reut F. A. Sagatova M. M. Adbullaeva M. M. Rakhimov 《Chemistry of Natural Compounds》2000,36(2):202-206
The transfer reaction of phosphatidylcholine and aqueous solutions of inositols that is catalyzed by phospholipase D is studied. Optimal conditions for synthesis of posphatidylinositol in a water—organicsolvent heterogeneous system are found. Addition of the alcoholic substrate methanol to the reaction medium is demonstrated to liberate myo-inositol from the phosphatidylinositol in hexane—water. Myo-inositol is isolated from a mixture of isomers by carrying out the double transfer reaction using phospholipase D.Mirzo Ulugbek National University of Uzbekistan. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 160–163, March–April, 2000. 相似文献
810.
FTIR studies of the CH3CN–BF3 complex in solid Ar, N2, and Xe: Matrix effects on vibrational spectra
FTIR spectra of the four isotopically substituted 1:1 complexes of acetonitrile and boron trifluoride were recorded in Ar, N2 and Xe matrices. In Ar, previously unreported three vibrational modes of the complex were clearly observed. Several significant vibrational bands were also observed in N2 and Xe. The observed frequency shifts on complexation, Δν, were qualitatively in good agreement with the computational results, which were calculated at the B3LYP/6-311++G(d,p) level using the optimized geometry of the C3v eclipsed conformation. The observed magnitudes of Δν for most of the complex bands were larger than the calculated values. The BF3 symmetric deformation mode is an exception. The observed frequency shits for this mode were smaller than the calculated values, especially in N2. This suggests that even an inert matrix can significantly affect the vibrational spectrum of the complex. 相似文献