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991.
Facile Synthesis of the Pentasaccharide Repeating Unit of the Exopolysaccharide from Cryptococcus neoformans Serotype D 下载免费PDF全文
Sheng‐Jun Huang Jun Liao Hong‐Gang Hu Qing‐Jie Zhao Qiu‐Ye Wu 《Helvetica chimica acta》2015,98(5):618-626
β‐D ‐GlcpA‐(1→2)‐[β‐D ‐Xylp‐(1→2)‐α‐D ‐Manp‐(1→3)]‐α‐D ‐Manp‐(1→3)‐α‐D ‐Manp, the repeating unit of the exopolysaccharide from Cryptococcus neoformans serotype D, was synthesized as its 4‐methoxyphenyl glycoside. The approach presented here also provides a route to the synthesis of more complex repeating units of glucuconoxylomannan (GXM) of C. neoformans serotypes A–C. 相似文献
992.
Convergence behavior of interior-point algorithms 总被引:4,自引:0,他引:4
We show that most interior-point algorithms for linear programming generate a solution sequence in which every limit point satisfies the strict complementarity condition. These algorithms include all path-following algorithms and some potential reduction algorithms. The result also holds for the monotone complementarity problem if a strict complementarity solution exists. In general, the limit point is a solution that maximizes the number of its nonzero components among all solutions.Research supported in part by NSF Grant DDM-8922636, the Iowa Business School Summer Grant, and the Interdisciplinary Research Grant of the University of Iowa Center for Advanced Studies. 相似文献
993.
An edge emitting laser with two symmetrical near-circular spots located far field (FF) is demonstrated using tapered double-sided Bragg reflection waveguides (BRWs). The BRWs consist of six pairs of top p-type and bottom n-type A10.Ga0.9 As/A10.3 Ga0.7As Bragg reflectors with a period thickness of 850 nm. The device has a 4° tapered angle configuration and exhibits two stable circular beams with a separation angle of 52°. Typical FF angles of 5.87° and 7.8° in the lateral and vertical directions, respectively, are achieved. The lateral FF angle in the ridged section is independent of the injection current (〉0.8 A) beeause of narrow ridge (-10 μm) confinement. By contrast, the FF angle in the tapered section shows an increase rate of 1.2 1.66°/A. The periodic modulation of the lasing wavelength is observed to be sensitive to self-heating effects. 相似文献
994.
Jian Ye Yipeng Zang Qingyu Wang Yida Zhang Da Sun Leijie Zhang Gongming Wang Xusheng Zheng Junfa Zhu 《Journal of Energy Chemistry》2021,(5):283-289
Performance breakthrough of electrocatalysts highly relies on the regulation of internal structures and electronic states.In present work,for the first time,we successfully synthesized nitrogen doped FeS2 nanoparticles(N-FeS2)as the electrocatalysts for hydrogen evolution reaction(HER).The band structure and electronic state of FeS2 are modulated by a nitrogen doping strategy,as confirmed by X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS)and density functional theory(DFT)calculations.Owing to the band structure and electronic state regulation as well as the weakening of H-S interaction,the designed N-FeS2 electrocatalyst exhibits superior catalytic performance with a low overpotential(~126 mV at 10 mA cm-2)and excellent activity stability under alkaline conditions,which is substantially improved as compared with that of the pure FeS2 counterpart.Our work demonstrates that the modulation of electron state and band structure of an electrocatalyst,which can provide a valuable guidance for designing excellent catalysts for hydrogen evolution reaction and beyond. 相似文献
995.
Zirbel JJ Ni KK Ospelkaus S D'Incao JP Wieman CE Ye J Jin DS 《Physical review letters》2008,100(14):143201
Using a Feshbach resonance, we create ultracold fermionic molecules starting from a Bose-Fermi atom gas mixture. The resulting mixture of atoms and weakly bound molecules provides a rich system for studying few-body collisions because of the variety of atomic collision partners for molecules; either bosonic, fermionic, or distinguishable atoms. Inelastic loss of the molecules near the Feshbach resonance is dramatically affected by the quantum statistics of the colliding particles and the scattering length. In particular, we observe a molecule lifetime as long as 100 ms near the Feshbach resonance. 相似文献
996.
Continuous wave (CW) operation of a c-cut Tm (5 at %), Ho (0.3 at %):YAP laser at 2132 nm wavelength were reported in this paper. In the temperature of 77 K, the Tm,Ho:YAP crystal was double end-pumped by a 21.4 W fiber-coupled laser diode (LD) at the center wavelength of 794.3 nm. Different resonator lengths and output couplers for the total pump power were tried. The resonator length was 205 mm, and the maximum CW output power of 6.17 W was acquired, corresponding to an optical-optical conversion efficiency of 28.8% and a slope efficiency of 35.6%. 相似文献
997.
998.
Juri Skotnitzki Alexander Kremsmair Daniel Keefer Ye Gong Regina de Vivie‐Riedle Paul Knochel 《Angewandte Chemie (International ed. in English)》2020,59(1):320-324
We report palladium‐catalyzed cross‐coupling reactions of chiral secondary non‐stabilized dialkylzinc reagents, prepared from readily available chiral secondary alkyl iodides, with alkenyl and aryl halides. This method provides α‐chiral alkenes and arenes with very high retention of configuration (dr up to 98:2) and satisfactory overall yields (up to 76 % for 3 reaction steps). The configurational stability of these chiral non‐stabilized dialkylzinc reagents was determined and exceeded several hours at 25 °C. DFT calculations were performed to rationalize the stereoretention during the catalytic cycle. Furthermore, the cross‐coupling reaction was applied in an efficient total synthesis of the sesquiterpenes (S)‐ and (R)‐curcumene with control of the absolute stereochemistry. 相似文献
999.
Zayats M Huang Y Gill R Ma CA Willner I 《Journal of the American Chemical Society》2006,128(42):13666-13667
A label free, reagentless aptasensor for adenosine is developed on an ISFET device. The separation of an aptamer/nucleic acid duplex by adenosine leads to the aptamer/adenosine complex that alters the gate potential of the ISFET. The sensitivity limit of the device is 5 x 10-5 M. Also, the immobilization of the aptamer/nucleic acid duplex on an Au-electrode and the separation of the duplex by adenosine mono-phosphate (AMP) enable the electrochemical detection of adenosine by faradaic impedance spectroscopy. The separation of the aptamer/nucleic acid duplex by adenosine and the formation of the aptamer/adenosine complex results in a decrease in the interfacial electron-transfer resistance in the presence of [Fe(CN)6]3-/4- as redox active substrate. 相似文献
1000.