Analgesic Buxus alkaloids with Enhanced Selectivity for the Low-Voltage-Gated Calcium Channel Cav3.2 over Cav3.1 through a New Binding Mode

Low-voltage-gated calcium channels (LVGCCs; Ca_v3.1-3.3) represent promising drug targets for epilepsy, pain, and essential tremor. At present, modulators with heightened selectivity for a subtype of LVGCCs are still highly desired. In this study we explored three classes of Buxus alkaloids and identified 9(10/19)abeo-artanes Buxusemine H and Buxusemine L (BXSL) as an unprecedented type of Ca_v3.2 inhibitors. Particularly, BXSL exhibited Ca_v3.2 inhibition comparable to Z944, a non-subtype-selective LVGCCs inhibitor under clinical trial. While lacking specificity for Ca_v3.3, BXSL showed a 30-fold selectivity of Ca_v3.2 over Ca_v3.1. As compared to several well-known inhibitors, the experimental and computational studies suggested BXSL exhibits a distinct binding mode to Ca_v3.2, notably through the essential interaction with serine-1543 in domain III. Furthermore, BXSL showed minimal impact on various recombinant and native nociceptive ion channels, while significantly reducing the excitability of isolated mouse dorsal root ganglion neurons. Animal studies in wild-type and Ca_v3.2 knock-out mice revealed that BXSL (5 mg/kg), by inhibiting Ca_v3.2, exhibits an analgesic effect equivalent to Z944 (10 mg/kg) or mibefradil (10 mg/kg). Moreover, we proposed a structural rationale for the high selectivity of 9(10/19)abeo-artane-type alkaloids towards Ca_v3.2 over Ca_v3.1. This study introduces a novel analgesic agent and valuable molecular insight for structure-based innovative Ca_v3.2 drug development.     

Preparation and Spectroscopy of Aluminosilicate Films Deposited on Graphite Surfaces via an Anhydrous Sol-Gel Route

Anhydrous aluminosilicate sols with Al : Si molar ratio ranging from 1 : 10 to 1 : 5 were prepared by a two-step anhydrous sol-gel process, in which tetraethoxysilane (TEOS) is pre-hydrolysed by formic acid, followed by addition of aluminium ethoxide. Unlike the case of aqueous sol-gel routes, where the Si–O–Al network homogeneity is greatly restricted by precipitation of Al(OH)₃, this anhydrous route yields clear, homogeneous sols. The sol formation and densification processes were investigated by infrared spectroscopy and X-ray powder diffraction (XRD) techniques, and the existence of Al–O–Si linkages was confirmed. To demonstrate an application of the anhydrous sol-gel process, aluminosilicate films were deposited onto graphite surfaces by dip coating and densified at 800°C under nitrogen, and their protective effect was evaluated.     

Toughness,trees, and walks

A graph is t‐tough if the number of components of G\S is at most |S|/t for every cutset S ⊆ V (G). A k‐walk in a graph is a spanning closed walk using each vertex at most k times. When k = 1, a 1‐walk is a Hamilton cycle, and a longstanding conjecture by Chvátal is that every sufficiently tough graph has a 1‐walk. When k ≥ 3, Jackson and Wormald used a result of Win to show that every sufficiently tough graph has a k‐walk. We fill in the gap between k = 1 and k ≥ 3 by showing that, when k = 2, every sufficiently tough (specifically, 4‐tough) graph has a 2‐walk. To do this we first provide a new proof for and generalize a result by Win on the existence of a k‐tree, a spanning tree with every vertex of degree at most k. We also provide new examples of tough graphs with no k‐walk for k ≥ 2. © 2000 John Wiley & Sons, Inc. J Graph Theory 33:125–137, 2000     

Two schemes of multiparty quantum direct secret sharing via a six-particle GHZ state

In this paper, two new efficient multiparty quantum direct secret sharing schemes are proposed via a six-particle GHZ state and Bell measurements. In the first scheme, based on the theory of security cryptanalysis, the secret message of the sender is directly encoded into the transmitted particles, and all the agents can obtain their information by performing bell measurement on the received particles, and then cooperate to recover the information of the sender. In the second scheme, we define a new secret shared coding method by performing local unitary operations on the transmitted particles, then agents perform Bell measurements on their own particles respectively, and feedback the measurement to the dealer. If the agent's results are matched with the previous coding method, the protocol will work out.In addition, the proposed two schemes have the following common advantages: the sender can send all prepared particles to the receiver, and can send an arbitrary key to the receiver, rather than a random secret key; the proposed schemes do not need to insert any detection sets to detect eavesdropping and can resist both existing attacks and spoofing attacks by dishonest agents. The sender need not to retain any photons, so the sender's quantum memory could be omitted here.     

Two Forms Schemes of Deterministic Remote State Preparation for Four-Qubit Cluster-Type State

Two deterministic schemes are put forward to preparing an arbitrary four-qubit cluster-type state remotely by using two Bell states as quantum channel. The coefficients of the prepared states can be not only real, but also complex. To accomplish the schemes, we introduce some novel sets of ingenious measurement basis vectors. Especially, for complex coefficients case, we give two different forms schemes. The receiver will reconstruct the initial state by means of some appropriate unitary operations. The outstanding advantage of the present schemes is that the success probability in all the considered remote state preparation (RSP) can reach 1.

     

硫酸水溶液中铅阳极膜形成及其结构的非现场FTIR反射吸收光谱—电化学研究

本文用非现场红外反射吸收光谱方法和电化学循环伏安法研究了1.0mol·dm~(-3)H_2SO_4中-0.6至2.5伏电势范围内(相对SCE)Pb阳极膜的形成及其可能的结构。在此电势区内Pb阳极膜中始终存在硫酸铅或碱式硫酸铅,其中SO_4~(2-)主要以桥式双齿配位方式与Pb~(2+)结合。另外,上述电势范围内生成的膜中无可检测量的H_2O和OH~-存在。     

研究型大学有机化学实验教学体系改革与创新

结合研究型大学有机化学实验教学体系创新实践,从＂基础—综合—提高＂的层次培养模式出发,构建有机化学实验教学课程体系、更新教学内容、加强基础研究与实验教学衔接、改进教学方法和手段、展示科学实验创新。     

Properties and asymptotic behavior of solutions of some problems of one-dimensional motion of a viscous barotropic gas

The work was supported by the Russian Foundation of Basic Research (Grant No. 93-011-1723).     

氧吸附对CdS—CdSe薄膜中少数载流子寿命的影响

空气中的氧在CdS-CdSe烧结膜中晶粒表面上的吸附,使晶粒的表面态发生变化,影响了晶粒中载流子的表面复合率.直流光电导衰退法测量结果表明.氧的吸附增大了CdS-CdSe薄膜中载流子的表面复合率,从而使少数载流子的有效寿命下降.     

Numerical solutions of Euler equations by using a new flux vector splitting scheme

A new flux vector splitting scheme has been suggested in this paper. This scheme uses the velocity component normal to the volume interface as the characteristic speed and yields the vanishing individual mass flux at the stagnation. The numerical dissipation for the mass and momentum equations also vanishes with the Mach number approaching zero. One of the diffusive terms of the energy equation does not vanish. But the low numerical diffusion for viscous flows may be ensured by using higher-order differencing. The scheme is very simple and easy to be implemented. The scheme has been applied to solve the one dimensional (1D) and multidimensional Euler equations. The solutions are monotone and the normal shock wave profiles are crisp. For a 1D shock tube problem with the shock and the contact discontinuities, the present scheme and Roe scheme give very similar results, which are the best compared with those from Van Leer scheme and Liou–Steffen's advection upstream splitting method (AUSM) scheme. For the multidimensional transonic flows, the sharp monotone normal shock wave profiles with mostly one transition zone are obtained. The results are compared with those from Van Leer scheme, AUSM and also with the experiment.