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991.
A lensed photonic crystal fiber (PCF) is proposed as an effective element for an optical free-space interconnector. By simultaneously forming a beam-expansion region and a focusing lens on a single piece of PCF, effective coupling between PCFs could be achieved. A long working distance of up to 1 mm with wide longitudinal and lateral tolerances was measured. The optical characteristics of the lensed PCFs and the connectors made from them are analyzed experimentally and theoretically. 相似文献
992.
Ikado K Abe K Abe K Adachi I Aihara H Akai K Akemoto M Anipko D Arinstein K Aulchenko V Aushev T Aziz T Bakich AM Balagura V Barbero M Bay A Bedny I Belous K Bitenc U Bizjak I Bondar A Bozek A Bracko M Browder TE Chang P Chen A Chen WT Choi Y Cole S Dalseno J Danilov M Dash M Eidelman S Epifanov D Flanagan J Fratina S Furukawa K Gabyshev N Gershon T Go A Gokhroo G Golob B Gorisek A Ha H Haba J Hara K Hara T Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou S Hou WS Iida N 《Physical review letters》2006,97(25):251802
We present the first evidence of the decay B- --> tau- nu(tau), using 414 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics and measure the branching fraction to be B(B- --> tau- nu(tau)) = (1.79(-0.49) +0.56(stat)(-0.51) +0.46(syst)) x 10(-4). This implies that fB = 0.229(-0.031) +0.036(stat)(-0.037) +0.034(syst) GeV and is the first direct measurement of this quantity. 相似文献
993.
Schümann J Wang CH Abe K Adachi I Aihara H Anipko D Arinstein K Asano Y Aushev T Bakich AM Balagura V Barberio E Barbero M Bay A Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Browder TE Chang MC Chang P Chao Y Chen A Chen WT Cheon BG Choi Y Choi YK Chuvikov A Cole S Dalseno J Danilov M Dash M Dragic J Drutskoy A Eidelman S Epifanov D Fratina S Gabyshev N Gershon T Go A Gokhroo G Golob B Gorisek A Ha HC Haba J Hara T Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T 《Physical review letters》2006,97(6):061802
We report evidence for the exclusive two-body charmless hadronic B meson decay B-->eta'pi, and improved measurements of B-->eta'K. The results are obtained from a data sample of 386x10(6) BB pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure B(B+-->eta'pi+)=[1.76(-0.62)(+0.67)(stat)(-0.14)(+0.15)(syst)]x10(-6) and B(B0-->eta'pi0)=[2.79(-0.96)(+1.02)(stat)(-0.34)(+0.25)(syst)]x10(-6). We also find the ratio of B(B+-->eta'K+)/B(B0-->eta'K0)=1.17+/-0.08(stat)+/-0.03(syst) and measure the direct CP asymmetries for the charged modes. 相似文献
994.
H.Y. Kwon M.J. Shin Y.J. Choi J.Y. Moon H.S. Ahn S.N. Yi S. Kim D.H. Ha S.H. Park 《Journal of Crystal Growth》2009,311(16):4146-4151
We fabricated one-dimensional GaN nanorods on AlN/Si (1 1 1) substrates at various temperatures, and carrier gas flow amount, using the hydride vapor phase epitaxy (HVPE) method. An AlN buffer layer of 50 nm thickness was deposited by RF sputtering for 25 min. Stalagmite-like GaN nanorods formed at a growth temperature of 650 °C. The diameters and lengths of GaN nanorods increase with growth time, whereas the density of nanorods decreases. And we performed the experiments by changing the carrier gas flow amount at a growth temperature of 650 °C and HCl:NH3 flow ratio of 1:40. GaN nanorods, with an average diameter of 50 nm, were obtained at a carrier gas flow amount of 1340 sccm. The shape, structures, and optical characteristics of the nanorods were investigated by field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence. 相似文献
995.
Haïkel Skhiri 《Acta Appl Math》2010,112(3):347-356
Let m(T) and q(T) be respectively the minimum and the surjectivity moduli of T∈ℬ(X), where ℬ(X) denotes the algebra of all bounded linear operators on a complex Banach space X. If there exists a semi-invertible but non-invertible operator in ℬ(X) then, given a surjective unital linear map φ: ℬ(X)⟶ℬ(X), we prove that m(T)=m(φ(T)) for all T∈ℬ(X), if and only if, q(T)=q(φ(T)) for all T∈ℬ(X), if and only if, there exists a bijective isometry U∈ℬ(X) such that φ(T)=UTU
−1 for all T∈ℬ(X). 相似文献
996.
Chien Thang Pham Thu Ha Nguyen Thi Nguyet Trieu Kenji Matsumoto Hung Huy Nguyen 《无机化学与普通化学杂志》2019,645(17):1072-1078
The bifunctional ligand 2,6‐dipicolinoylbis(N,N‐diethylthiourea) (H2L) readily reacts with mixtures of Zn(CH3COO)2 and LnCl3 in MeOH at ambient temperature with formation of trinuclear heterobimetallic complexes [Zn2Ln(L)2(OAc)3] ( 1a – 1f ) (Ln = Ce, Nd, Sm, Gd, Dy, Er). The X‐ray single‐crystal diffraction and structural studies of the complexes revealed their isostructural nature, in which two doubly‐charged ligands {L2–} bind two Zn2+ ions with the terminal acylthiourea sites and one Ln3+ ion with the central 2,6‐pyridinedicarboxamide site. In the complexes, the coordination numbers of LnIII and ZnII ions are 9 and 5, respectively. Magnetic properties of the complexes were studied by temperature‐dependent dc magnetic measurements. The observed μeff values at room temperature are all closed to the calculated values. Fitting χM and M data of [Zn2Gd(L)2(OAc)3] ( 1d ) shows a giso value of 1.94. 相似文献
997.
Lipid nanoparticles (LNPs) have been employed for drug delivery in small molecules, siRNA, mRNA, and pDNA for both therapeutics and vaccines. Characterization of LNPs is challenging because they are heterogeneous mixtures of large complex particles. Many tools for particle size characterization, such as dynamic and static light scattering, have been applied as well as morphology analysis using electron microscopy. CE has been applied for the characterization of many different large particles such as liposomes, polymer, and viruses. However, there have been limited efforts to characterize the surface charge of LNPs and CIEF has not been explored for this type of particle. Typically, LNPs for delivery of oligonucleotides contain at least four different lipids, with at least one being an ionizable cationic lipid. Here, we describe the development of an imaged capillary isoelectric focusing method used to measure the surface charge (i.e., pI) of an LNP‐based mRNA vaccine. This method is capable of distinguishing the pI of LNPs manufactured with one or more different ionizable lipids for the purpose of confirming LNP identity in a manufacturing setting. Additionally, the method is quantitative and stability‐indicating making it suitable for both process and formulation development. 相似文献
998.
Young‐Hoon Chung Min Gwan Ha Youngseung Na Hee‐Young Park Hyoung‐Juhn Kim Dirk Henkensmeier Sung Jong Yoo Jin Young Kim So Young Lee Seung Woo Lee Hyun S. Park Yong‐Tae Kim Jong Hyun Jang 《Electroanalysis》2019,31(7):1401-1408
The ability to capture, store, and use CO2 is important for remediating greenhouse‐gas emissions and combatting global warming. Herein, Au nanoparticles (Au‐NPs) are synthesized for effective electrochemical CO2 reduction and syngas production, using polyethylenimine (PEI) as a ligand molecule. The PEI‐assisted synthesis provides uniformly sized 3‐nm Au NPs, whereas larger irregularly shaped NPs are formed in the absence of PEI in the synthesis solution. The Au‐NPs synthesized with PEI (PEI?Au/C, average PEI Mw=2000) exhibit improved CO2 reduction activities compared to Au‐NPs formed in the absence of PEI (bare Au NPs/C). PEI?Au/C displays a 34 % higher activity toward CO2 reduction than bare Au NPs/C; for example, PEI?Au/C exhibits a CO partial current density (jCO) of 28.6 mA cm?2 at ?1.13 VRHE, while the value for bare Au NPs/C is 21.7 mA cm?2; the enhanced jCO is mainly due to the larger surface area of PEI?Au/C. Furthermore, the PEI?Au/C electrode exhibits stable performance over 64 h, with an hourly current degradation rate of 0.25 %. The developed PEI?Au/C is employed in a CO2‐reduction device coupled with an IrO2 water‐oxidation catalyst and a proton‐conducting perfluorinated membrane to form a PEI?Au/C|Nafion|IrO2 membrane‐electrode assembly. The device using PEI?Au/C as the CO2‐reduction catalyst exhibits a jCO of 4.47 mA/cm2 at 2.0 Vcell. Importantly, the resulted PEI?Au/C is appropriate for efficient syngas production with a CO ratio of around 30–50 %. 相似文献
999.
Anthony Keyes Hatice E. BasbugAlhan Estela Ordonez Uyen Ha Dain B. Beezer Huong Dau Yu‐Sheng Liu Enkhjargal Tsogtgerel Glen R. Jones Eva Harth 《Angewandte Chemie (International ed. in English)》2019,58(36):12370-12391
The inherent differences in reactivity between activated and non‐activated alkenes prevents copolymerization using established polymer synthesis techniques. Research over the past 20 years has greatly advanced the copolymerization of polar vinyl monomers and olefins. This Review highlights the challenges associated with conventional polymerization systems and evaluates the most relevant methods which have been developed to “bridge the gap” between polar vinyl monomers and olefins. We discuss advancements in heteroatom tolerant coordination–insertion polymerizations, methods of controlling radical polymerizations to incorporate olefinic monomers, as well as combined approaches employing sequential polymerizations. Finally, we discuss state‐of‐the‐art stimuli‐responsive systems capable of facile switching between catalytic pathways and provide an outlook towards applications in which tailored copolymers are ideally suited. 相似文献
1000.
Maike Andresen Dr. Isabelle Kleiner Prof. Dr. Martin Schwell Prof. Dr. Wolfgang Stahl Dr. Ha Vinh Lam Nguyen 《Chemphyschem》2019,20(16):2063-2073
Using two molecular jet Fourier transform spectrometers, the microwave spectrum of hexan-2-one, also called methyl n-butyl ketone, was recorded in the frequency range from 2 to 40 GHz. Three conformers were assigned and fine splittings caused by the internal rotations of the two terminal methyl groups were analyzed. For the acetyl methyl group CH3 COC3H6CH3, the torsional barrier is 186.9198(50) cm−1, 233.5913(97) cm−1, and 182.2481(25) cm−1 for the three observed conformers, respectively. The value of this parameter could be linked to the structure of the individual conformer, which enabled us to create a rule for predicting the barrier height of the acetyl methyl torsion in ketones. The very small splittings arising from the internal rotation of the butyl methyl group CH3COC3H6 CH3 could be resolved as well, yielding the respective torsional barriers of 979.99(88) cm−1, 1016.30(77) cm−1, and 961.9(32) cm−1. 相似文献