Organometallic chiral liquid crystals: bis{4-[ω-(cholest-5-en-3-yloxycarbonyl)alkoxy]phenylethynyl}mercury complexes

We report the synthesis and thermal behaviour of the first chiral organometallic trimesogens having bis[(4-phenyl)ethynyl]mercury as the central core connected on either side to cholesteryl ester moieties through either even-even (C₄) or odd-odd (C₃, C₅ and C₇) central alkylene spacers. All the organomercury trimesogens exhibit a chiral nematic phase. These mercury complexes are extremely sensitive to heat, in a manner reminiscent of other reports.     

一种新的偶奇非线性相干态中测量相位算符的压缩效应

利用Bamett和pegg提出的测量相位算符讨论了一种新的偶奇非线性相干态的压缩效应。结果表明，在这种偶奇非线性相干态中测量相位算符不存在CN和SN类压缩，只存在CS类压缩。利用数值计算方法研究了CS类压缩效应，结果表明与通常的偶奇相干态的不同的是，偶非线性相干态在大区域内出现压缩效应而奇非线性相干态在小区域内才出现压缩效应。     

Twist Sensitivity of Cladding-Mode Resonances and Its Cross-Sensitivity to Strain and Temperature in a Mechanically Induced Long-Period Fiber Grating

Abstract

Twist sensitivity of cladding-mode resonances in a mechanically induced long-period fiber grating formed over a single-mode fiber is experimentally demonstrated and theoretically analyzed. Of the two usual cladding-mode resonances corresponding to LP₁₁ and LP₁₂, higher-order mode LP₁₂ is more sensitive to twist in comparison with the lower-order mode LP₁₁. The extent of down-shifting of resonant wavelengths depends on twist-induced circular birefringence and the modal field distribution of the cladding-modes inside the fiber. When the fiber is severely twisted to 3.5 rad/cm, a shift sensitivity is observed of 1 nm/(rad/cm) for the LP₁₁ mode and 4.23 nm/(rad/cm) for the LP₁₂ mode. The fiber breaks when the twist rate exceeds 3.5 rad/cm. In comparison with LP₁₂, the LP₁₁ resonance is almost independent of the axial strain variation with an ultra-low sensitivity of 0.18 pm/με, and it is also almost insensitive to the temperature variation with a coefficient of 35 pm/°C. Forming the LP₁₁ resonance far away from its cut-off wavelength, a widely tunable band-pass filter is also demonstrated with a very high twist sensitivity of 8.75 nm/(rad/cm) and negligible cross-sensitivity to strain and temperature. The experimental and theoretical results are very useful in selecting sensitive and stable cladding-mode resonances in the design of new mechanically induced long-period fiber gratings based torsion sensors and tunable band-pass filters.     

Exciton binding energy in a pyramidal quantum dot

The effects of spatially dependent effective mass, non-parabolicity of the conduction band and dielectric screening function on exciton binding energy in a pyramid-shaped quantum dot of GaAs have been investigated by variational method as a function of base width of the pyramid. We have assumed that the pyramid has a square base with area \(a\times a\) and height of the pyramid \(H=a/2\). The trial wave function of the exciton has been chosen according to the even mirror boundary condition, i.e. the wave function of the exciton at the boundary could be non-zero. The results show that (i) the non-parabolicity of the conduction band affects the light hole (lh) and heavy hole (hh) excitons to be more bound than that with parabolicity of the conduction band, (ii) the dielectric screening function (DSF) affects the lh and hh excitons to be more bound than that without the DSF and (iii) the spatially dependent effective mass (SDEM) affects the lh and hh excitons to be less bound than that without the SDEM. The combined effects of DSF and SDEM on exciton binding energy have also been calculated. The results are compared with those available in the literature.     

傅里叶变换红外光谱仪—微量金刚石池采样附件在药物分析中的应用

本文选用常见催眠镇静药及精神失常等类药三十余种，应用傅里叶变换红外光谱仪微量金刚石池附件（ＦＴＩＲ－ＤＡＣ）采样分析，对于标示药量不低于药重１／３的药物片（粉）剂可以通过直接测试谱图认定药物；对于药物纯品，最低检出量可以２×１０＾－７ｇ；对于薄层层分离后的药物斑点的检验，以苯巴比妥为例，本法可最低检出５×１０＾－６ｇ。本实验方法检定药物快速、灵敏、准确。     

Dynamical analysis and FPGA implementation of a chaotic oscillator with fractional-order memristor components

Memristor-based chaotic and hyperchaotic systems are of great interest in the recent years, and addition of meminductor and memcapacitors to the family has widened the applications. In this paper, we propose a new chaotic system with fractional-order memristor and memcapacitor components. Nonlinear chaotic properties of the proposed system are investigated with equilibrium points, eigenvalues, Lyapunov exponents, bifurcation and bicoherence plots. We show that a small model disturbance can make the system to show self-excited and hidden attractors. We use the Adomian Decomposition method for implementing the proposed system in Field Programmable Gate Arrays.     

Molecular encapsulation of amodiaquine in 2-hydroxypropyl β-cyclodextrin cavity. Characterization and its in vitro cytotoxicity

Amodiaquine has been used widely as an antimalarial drug. Amodiaquine is a mannich base 4-amino quinolone with a mode of action similar to that of chloroquine. The inclusion complex of amodiaquine with 2-(hydroxypropyl)-beta-cyclodextrin in solution phase is studied from the ground and excited state with absorption and fluorescence spectroscopic techniques, respectively. A binding constant and stoichiometric ratio between amodiaquine and 2-(hydroxypropyl)-beta-cyclodextrin are calculated by the use of Benesi–Hildebrand equation. The solid complexes are prepared by physical, kneading and coprecipitation methods. The solid complexes are characterized by Fourier-transform infrared spectral analysis, Differential scanning calorimetric curves and powder X-ray diffraction patterns. The anticancer activity was tested for pure amodiaquine and their complex with 2-(hydroxypropyl)-beta-cyclodextrin against MDA MB 231 cell line. It clearly showed that a significant improvement of anticancer activity of amodiaquine when forming a complex with 2-(hydroxypropyl)-beta-cyclodextrin.     

Controlling chaos and supressing chimeras in a fractional-order discrete phase-locked loop using impulse control

A fractional-order difference equation model of a third-order discrete phase-locked loop (FODPLL) is discussed and the dynamical behavior of the model is demonstrated using bifurcation plots and a basin of attraction. We show a narrow region of loop gain where the FODPLL exhibits quasi-periodic oscillations, which were not identified in the integer-order model. We propose a simple impulse control algorithm to suppress chaos and discuss the effect of the control step. A network of FODPLL oscillators is constructed and investigated for synchronization behavior. We show the existence of chimera states while transiting from an asynchronous to a synchronous state. The same impulse control method is applied to a lattice array of FODPLL, and the chimera states are then synchronized using the impulse control algorithm. We show that the lower control steps can achieve better control over the higher control steps.     

Transfer Catalysis Between Two Solids: Application to the Reduction of Nitroarenes

A wide range of aromatic nitro compounds can be reduced to anilines through the use of a Cr^II/Mn⁰ redox couple in the presence of trimethylsilyl chloride [TMSCl, Eq. (1)]. Only 0.25 equivalents of chromium are required to reduce solid-supported nitroarenes (R=solid support); this represents a rare case of transfer catalysis between two solid phases. The reaction is also amenable to solution-phase synthesis (R=OH).     

Control of the PEO chain conformation on nanoparticles by adsorption of PEO-block-poly(L-lysine) copolymers and its significance on colloidal stability and protein repellency

The physical adsorption of PEO(n)-b-PLL(m) copolymers onto silica nanoparticles and the related properties of poly(ethylene oxide) (PEO)-coated particles were studied as a function of the block copolymer composition. Copolymers adopt an anchor-buoy conformation at the particle surface owing to a preferential affinity of poly(L-lysine) (PLL) blocks with the silica surface over PEO blocks when a large excess of copolymer is used. The interdistance between PEO chains at particle surface is highly dependent on the size of PLL segments; a dense brush of PEO is obtained for short PLL blocks (DP = 10), whereas PEO chains adopt a so-called interacting "mushroom" conformation for large PLL blocks (DP = 270). The size of the PEO blocks does not really influence the copolymer surface density, but it has a strong effect on the PEO layer thickness as expected. Salt and protein stability studies led to similar conclusions about the effectiveness of a PEO layer with a dense brush conformation to prevent colloidal aggregation and protein adsorption. Besides, a minimal PEO length is required to get full stabilization properties; as a matter of fact, both PEO(45)-b-PLL(10) and PEO(113)-b-PLL(10) give rise to a PEO brush conformation but only the latter copolymer efficiently stabilizes the particles in the presence of salt or proteins.