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Dr. Isaac Omari Dr. Lars P. E. Yunker Dr. Johanne Penafiel Darlene Gitaari Atzin San Roman Prof. J. Scott McIndoe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3812-3816
Organotrifluoroborates serve as coupling partners during transmetalation in the Suzuki–Miyaura reaction but require hydrolysis prior to the coupling reaction. Their anionic nature allows study of their hydrolysis by electrospray ionization mass spectrometry (ESI-MS) through real-time monitoring, complemented by pH analysis. The induction period varied according to the borates employed, and a dynamic series of equilibria for numerous ions was observed during hydrolysis. We found that the induction periods and reaction rates were sensitive to the R group of the borates, the shape of the reaction vessel, and stir rate. 相似文献
64.
We implement a dynamic model that describes the polarization behavior in vertical-cavity surface-emitting lasers that contain an absorbing region surrounding the active zone. We find four regions of qualitatively different behavior: stable linearly polarized operation, intensity pulsations of a linearly polarized component, pulsations of both total-intensity and polarization components, and polarization self-pulsation with constant total intensity. We characterize the four regions by computing the polarization-resolved optical and power spectra. The predicted behavior agrees with recent experimental results. 相似文献
65.
用荧光染色技术及流式细胞仪分析方法研究了 A1/京防861 和 B/沪防931 两株流感病毒感染与细胞凋亡的关系,探讨利用嗜麦芽假单胞菌黑色素抑制流感病毒诱导 M D C K 细胞凋亡的可能性 结果显示:黑色素在 100 m g· L- 1 浓度范围内,对 M D C K 细胞无细胞毒性; A1/京防 861 和 B/沪防 931 两株流感病毒均可诱导 M D C K细胞凋亡,但二者存在毒力差异(p< 0.05)病毒感染12 h 后,荧光染色可观察到典型的凋亡核形态,流式细胞仪则可检测到病毒诱导 M D C K 细胞产生的凋亡峰,且细胞凋亡率分别为37.02% 和 2729% ;20 m g· L- 1 的黑色素可有效抑制两株流感病毒诱导细胞凋亡,使细胞凋亡指数从25% ~35% 降至3% 以下 结果表明,黑色素可以抑制 A 和 B型流感病毒诱导细胞凋亡 相似文献
66.
Balle S Tolkachova E San Miguel M Tredicce JR Martín-Regalado J Gahl A 《Optics letters》1999,24(16):1121-1123
We analyze polarization switching in vertical-cavity surface-emitting lasers, taking into account a proper semiconductor frequency-dependent complex susceptibility and spin-flip processes. Thermal effects are included as a varying detuning, and gain differences arise from birefringence splitting. We find that, for large birefringence, gain differences between the two linearly polarized modes are preponderant, and switching occurs owing to thermal shift. For small birefringence polarization switching from the high- to the low-gain mode occurs owing to the combined effect of birefringence and semiconductor phase-amplitude-coupled dynamics for a finite value of the carrier spin-flip rate. 相似文献
67.
We consider stochastic differential equations of the Langevin type in which the noise enters nonlinearly. In particular we study quadratic gaussian noise and we derive equations for the probability density under different approximations. In the limit of small intensity and small correlation time of the noise we obtain a Fokker-Planck equation which accounts for the main effects of the nonlinear noise. We present some examples and we discuss the consequences of our results in the analysis of an electrohydrodynamic instability in liquid crystals in the presence of external noise. 相似文献
68.
We describe the topological structure and the underlying organization principles of the directories created by users of a computer cluster. Users create trees with a scale-free degree distribution whose properties are reproduced by a growth and preferential attachment mechanism with a single parameter. The degree distribution has a nonuniversal exponent associated with different values of the parameter. However, the distribution of branch sizes has a universal exponent analytically obtained from the model. 相似文献
69.
In this Letter, we construct the quantum algorithms for the Simon problem and the period-finding problem, which do not require initializing the auxiliary qubits involved in the process of functional evaluation but are as efficient as the original algorithms. In these quantum algorithms, one can use any arbitrarily mixed state as the auxiliary qubits, and furthermore can recover the state of the auxiliary qubits to the original one after completing the computations. Since the recovered state can be employed in any other computations, we obtain that a single preparation of the auxiliary qubits in an arbitrarily mixed state is sufficient to implement the iterative procedure in the Simon algorithm or the period-finding algorithm. 相似文献
70.
We have carried out a systematic study of oxygen vacancy formation on the TiO2 (110) surface by means of plane-wave pseudopotential density-functional theory calculations. We have used models with the mean number of vacancies per surface unit cell being theta=0.25 and theta=0.5. The study comprises several kind of vacancies within the outermost layers of the surface. The use of a suitable set of technical parameter is often essential in order to get accurate results. We find that the presence of bridging vacancies is energetically favored in accordance to experimental data, although the formation of sub-bridging vacancies might be possible at moderate temperatures. Surprisingly, the spin state of the vacancy has little influence on the results. Atomic displacements are also analyzed and found to be strongly dependent on the particular arrangement of vacancies. 相似文献