Poly(2,5‐dihydroxy‐1,4‐phenylene benzobisthiazole)/poly(1,4‐phenylene benzobisthiazole) copolymers: Chain packing and properties

Crystal‐packing, optical, and electrical properties of poly(2,5‐dihydroxy‐1,4‐phenylene benzobisthiazole) (DiOH‐PBZT) and copolymers of DiOH‐PBZT/poly(1,4‐phenylene‐benzobisthiazole) (PBZT) were examined. Intramolecular hydrogen bonds between the hydroxyl units and the neighboring nitrogen atoms, as evidenced by the IR spectra, led to the formation of a pseudoladder chain structure and changed the chain packing. The (200) and (010) planes were both affected by the copolymer composition, with the (200) plane spacing increasing from 5.895 to 6.482 Å and the (010) plane spacing decreasing from 3.539 to 3.404 Å with the transition from the unsubstituted PBZT homopolymer to the DiOH‐PBZT homopolymer. The cell dimensions of the copolymers were simple averages of those of the individual homopolymers, suggesting the isomorphic crystal structure formation of the two units. The c‐axis spacing, however, remained unchanged. The increase in the conjugation length of the copolymers as the dihydroxy content increased was confirmed by the bathochromic shift of the absorption band in the ultraviolet–visible spectra. The intrinsic conductivities of the copolymers were 3 orders of magnitude higher than that of the unsubstituted PBZT. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 559–565, 2001     

Simplification of the Gram Matrix Eigenvalue Problem for Quadrature Amplitude Modulation Signals

In quantum information science, it is very important to solve the eigenvalue problem of the Gram matrix for quantum signals. This allows various quantities to be calculated, such as the error probability, mutual information, channel capacity, and the upper and lower bounds of the reliability function. Solving the eigenvalue problem also provides a matrix representation of quantum signals, which is useful for simulating quantum systems. In the case of symmetric signals, analytic solutions to the eigenvalue problem of the Gram matrix have been obtained, and efficient computations are possible. However, for asymmetric signals, there is no analytic solution and universal numerical algorithms that must be used, rendering the computations inefficient. Recently, we have shown that, for asymmetric signals such as amplitude-shift keying coherent-state signals, the Gram matrix eigenvalue problem can be simplified by exploiting its partial symmetry. In this paper, we clarify a method for simplifying the eigenvalue problem of the Gram matrix for quadrature amplitude modulation (QAM) signals, which are extremely important for applications in quantum communication and quantum ciphers. The results presented in this paper are applicable to ordinary QAM signals as well as modified QAM signals, which enhance the security of quantum cryptography.     

多接收电感耦合等离子体质谱测定氙同位素比值研究

核爆炸产生的氙（Xe）同位素是全面禁止核试验条约的重要监测对象。该文建立了大气气溶胶中Xe同位素比值的多接收电感耦合等离子体质谱（MC－ICP－MS）分析方法。通过研发Xe的富集纯化平台,使用高纯氩气（99.999%）为载体,有效降低了大气气溶胶中残留颗粒物和有机物对质谱测量的影响。为提高信号稳定性,建立了MC－ICP－MS专用Xe气体进样系统,通过活性炭吸附质谱样品气的Xe、气体进样系统烘烤和抽真空2 h等措施,有效降低了记忆效应和系统本底,129Xe的本底信号强度从3.0 × 10-2 V降至小于2.7 × 10-3 V,Xe本底对样品比值测量的影响小于万分之一。采用标准样品交叉法校正质量分馏效应,在24 h内穿插测量7次Xe质控标样,Xe同位素比值测量精密度小于0.09%,对130Xe/131Xe和132Xe/131Xe测量精密度小于0.008%,测量结果与参考值在不确定度范围内一致。采用该方法有效鉴别了Xe同位素组成存在差异的实际样品。该文建立的Xe同位素比值的MC－ICP－MS测量技术精密度高,结果准确,可为Xe监测事件识别及溯源等研究提供可靠数据。     

Neuroprotective Effects of Green Tea Seed Isolated Saponin Due to the Amelioration of Tauopathy and Alleviation of Neuroinflammation: A Therapeutic Approach to Alzheimer’s Disease

Tauopathy is one of the major causes of neurodegenerative disorders and diseases such as Alzheimer’s disease (AD). Hyperphosphorylation of tau proteins by various kinases leads to the formation of PHF and NFT and eventually results in tauopathy and AD; similarly, neuroinflammation also exaggerates and accelerates neuropathy and neurodegeneration. Natural products with anti-tauopathy and anti-neuroinflammatory effects are highly recommended as safe and feasible ways of preventing and /or treating neurodegenerative diseases, including AD. In the present study, we isolated theasaponin E1 from ethanol extract of green tea seed and evaluated its therapeutic inhibitory effects on tau hyper-phosphorylation and neuroinflammation in neuroblastoma (SHY-5Y) and glioblastoma (HTB2) cells, respectively, to elucidate the mechanism of the inhibitory effects. The expression of tau-generating and phosphorylation-promoting genes under the effects of theasaponin E1 were determined and assessed by RT- PCR, ELISA, and western blotting. It was found that theasaponin E1 reduced hyperphosphorylation of tau and Aβ concentrations significantly, and dose-dependently, by suppressing the expression of GSK3 β, CDK5, CAMII, MAPK, EPOE4(E4), and PICALM, and enhanced the expression of PP1, PP2A, and TREM2. According to the ELISA and western blotting results, the levels of APP, Aβ, and p-tau were reduced by treatment with theasaponin E1. Moreover, theasaponin E1 reduced inflammation by suppressing the Nf-kB pathway and dose-dependently reducing the levels of inflammatory cytokines such as IL-1beta, IL-6, and TNF-alpha etc.     

化学镀镍—高磷合金的微观结构及晶化行为研究

采用混合络合剂在酸性体系中进行化学镀镍－高磷合金,并用原子力显微镜（AFM）,透射电镜（TEM）、差热分析（DSC）、X射线衍射（XRD）等技术研究所得到的化学镀镍－高磷合金的微观结构和晶化行为。结果表明,化学镀镍－高磷合金具有胞状结构的微观形貌,镀态时呈典型的非晶态结构,300℃以下对热非常。镀层在343．8℃开始晶化,400℃时完全转化成亚稳用Ni5P2,440.4 ℃,时进一步转变成稳定的Ni和Ni3P相其晶化行为同从碱性乙二胺镀液中得到的高磷化学镀镍层有明显的差异。     

The Strongly Simple Cycles with Given Rotation Pairs of an Interval Map

In this paper, we introduce the notion of the strongly simple cycles with some rotation pair for interval maps and prove that, if an interval map has a cycle with given rotation pair, then it, has a strongly simple cycle with the same rotation pair.     

Synthesis and characterization of light‐emitting oligo(p‐phenylene‐vinylene)s and polymeric derivatives containing three‐ and five‐conjugated phenylene rings. II. Electro‐optical properties and optimization of PLED performance

A series of multilayer polymeric light‐emitting diodes (PLEDs) containing an electron‐transporting layer (ETL), that is tris(8‐quinolinolato)‐aluminum(III) (Alq) and 2,2′,2″‐(1,3,5‐phenylene)‐tris[1‐phenyl‐1H‐benzimidazole] (TPBI), were fabricated by doping fluorescent oligo(p‐phenylene‐vinylene)s (BIII and BV) and polymer derivatives (PBV) into poly(N‐vinyl carbazole) (PVK). These PLEDs can be optimized by the design of multilayer device configurations (brightness increased 8–15 times by addition of ETL) and possess greenish electroluminescent (EL) spectra peaked about 500–540 nm. A remarkably high brightness of 56,935 cd/m² with a power efficiency of 3.25 lm/W was obtained in the device of PVK:BVOC₈‐OC₈ (100:20)/Alq (60 nm/60 nm). It suggests that the emission mechanism (including the conjugated and excimer emissions of BVOC₈‐OC₈ emitters) originates from both of BVOC₈‐OC₈ and ETL (Alq and TPBI) by varying the concentration of chromophores and adjusting the thickness of ETL. The concentration effect of the emitters in PVK (i.e. PVK:BVOC₈‐OC₈ = 100:5, 100:20, and 100:100 wt %) and the influence of the ETL (including its thickness) on the EL characteristics are also reported. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2922–2936, 2006     

A New Chromone Glycoside from Cassia siamea Lam.

Cassia siamea Lam. (CSL) is a common tree in the southern part of China. It has been used as folk medicine for aperient, antiarthritic and swellings1. We report here the isolation and structural elucidation of a new chromone glucoside, 2-methyl-5-propyl-7, 12-dihydroxy chromone-12-O-(-D-glucopyranoside (1), from the n-butanol-soluble fraction of CSL extract . 1The 80% ethanolic extract of CSL was dissolved in water and partitioned with petroleum ether, dichloromethane and n-butanol. The …     

On‐Surface Cyclization of Tetrapeptides Using Molecularly Imprinted Polymers as Non‐Covalent Auxiliaries

Based on the fabrication of molecularly imprinted polymeric film on cellulose paper (MIFC), we have developed a robotic system for homodetic tetrapeptide cyclization. We constructed molecularly imprinted polymeric film (MIPF) on cellulose paper as the non‐covalent auxiliary to assist cyclic tetrapeptide (CTP) formation. Tetrapeptides were bound by their hydrophobic interaction with MIFC. With the help of MIFC and a coupling reagent, quantitative synthesis of CTPs was achieved conveniently for various tetrapeptides. The syntheses of cyclic tetrapeptide (CTP) could also be facilitated using the MIFC induced from CTP or other tetrapeptides with partially matched sequences.