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71.
In the present study the capacity of Radix Paeoniae Rubra aqueous extract (RPRAE) as an antioxidant to protect against carbon tetrachloride (CCl(4))-induced oxidative stress and hepatotoxicity in Wistar rats was investigated. Six groups of rats were used. Radix Paeoniae Rubra aqueous extract (100 or 200 or 300 mg/kg of bw) or bifendate (100 mg/kg of bw) were given daily by gavage to the animals on 28 consecutive days to elucidate the protective effects against CCl(4)-induced hepatotoxicity. The 20% CCl(4)/olive oil was gavage of gastric tube twice a week (on the third and seventh days of each week). The animals of normal control group were given only vehicle. The animals of CCl(4)-treated group were administered with CCl(4) twice a week (on the third and seventh days of each week) and with vehicle on rest of the days. The test materials were found effective as hepatoprotective agents, as evidenced by plasma and liver biochemical parameters. Therefore, the results of this study show that Radix Paeoniae Rubra aqueous extract can protect the liver against CCl(4)-induced oxidative damage in rats, and the hepatoprotective effects might be correlated with its antioxidant and free radical scavenger effects. 相似文献
72.
The purpose of this paper is to give a characterization of real hypersurfaces of type A0, A in a quaternionic hyperbolic space
QH
m by the covariant derivative of the second fundamental tensor.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
73.
In this paper, according to a certain criterion, we divide the exponential distribution class into some subclasses. One of them is closely related to the regular-variation-tailed distribution class, and is called the semi-regular-variation-tailed distribution class. The new class possesses several nice properties, although distributions in it are not convolution equivalent. We give the precise tail asymptotic expression of convolutions of these distributions, and prove that the class is closed under convolution. In addition, we do not need to require the corresponding random variables to be identically distributed. Finally, we apply these results to a discrete time risk model with stochastic returns, and obtain the precise asymptotic estimation of the finite time ruin probability. 相似文献
74.
Ruiling Zhang Xin Mao Yang Yang Songqiu Yang Wenyuan Zhao Tuerdi Wumaier Donghui Wei Weiqiao Deng Keli Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2751-2755
Lead‐free zero‐dimensional (0D) organic‐inorganic metal halide perovskites have recently attracted increasing attention for their excellent photoluminescence properties and chemical stability. Here, we report the synthesis and characterization of an air‐stable 0D mixed metal halide perovskite (C8NH12)4Bi0.57Sb0.43Br7?H2O, in which individual [BiBr6]3? and [SbBr6]3? octahedral units are completely isolated and surrounded by the large organic cation C8H12N+. Upon photoexcitation, the bulk crystals exhibit ultra‐broadband emission ranging from 400 to 850 nm, which originates from both free excitons and self‐trapped excitons. This is the first example of 0D perovskites with broadband emission spanning the entire visible spectrum. In addition, (C8NH12)4Bi0.57Sb0.43Br7?H2O exhibits excellent humidity and light stability. These findings present a new direction towards the design of environmentally‐friendly, high‐performance 0D perovskite light emitters. 相似文献
75.
Yu Wang Nadine Tappertzhofen Daniel Mndez‐Snchez Maria Bawn Boyu Lyu John M. Ward Helen C. Hailes 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10226-10231
The benzylisoquinoline alkaloids (BIAs) are an important group of secondary metabolites from higher plants and have been reported to show significant biological activities. The production of BIAs through synthetic biology approaches provides a higher‐yielding strategy than traditional synthetic methods or isolation from plant material. However, the reconstruction of BIA pathways in microorganisms by combining heterologous enzymes can also give access to BIAs through cascade reactions. Most importantly, non‐natural BIAs can be generated through such artificial pathways. In the current study, we describe the use of tyrosinases and decarboxylases and combine these with a transaminase enzyme and norcoclaurine synthase for the efficient synthesis of several BIAs, including six non‐natural alkaloids, in cascades from l ‐tyrosine and analogues. 相似文献
76.
Mykola Telychko Jie Su Aurelio Gallardo Yanwei Gu Jesús I. Mendieta‐Moreno Dongchen Qi Anton Tadich Shaotang Song Pin Lyu Zhizhan Qiu Hanyan Fang Ming Joo Koh Jishan Wu Pavel Jelínek Jiong Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18764-18770
The ability to use mechanical strain to steer chemical reactions creates completely new opportunities for solution‐ and solid‐phase synthesis of functional molecules and materials. However, this strategy is not readily applied in the bottom‐up on‐surface synthesis of well‐defined nanostructures. We report an internal strain‐induced skeletal rearrangement of one‐dimensional (1D) metal–organic chains (MOCs) via a concurrent atom shift and bond cleavage on Cu(111) at room temperature. The process involves Cu‐catalyzed debromination of organic monomers to generate 1,5‐dimethylnaphthalene diradicals that coordinate to Cu adatoms, forming MOCs with both homochiral and heterochiral naphthalene backbone arrangements. Bond‐resolved non‐contact atomic force microscopy imaging combined with density functional theory calculations showed that the relief of substrate‐induced internal strain drives the skeletal rearrangement of MOCs via 1,3‐H shifts and shift of Cu adatoms that enable migration of the monomer backbone toward an energetically favorable registry with the Cu(111) substrate. Our findings on this strain‐induced structural rearrangement in 1D systems will enrich the toolbox for on‐surface synthesis of novel functional materials and quantum nanostructures. 相似文献
77.
Yan Lyu Shasha He Jingchao Li Yuyan Jiang He Sun Yansong Miao Kanyi Pu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18365-18369
Noninvasive regulation of CRISPR/Cas9 gene editing is conducive to understanding of gene function and development of gene therapy; however, it remains challenging. Herein, a photolabile semiconducting polymer nanotransducer (pSPN) is synthesized to act as the gene vector to deliver CRISPR/Cas9 plasmids into cells and also as the photoregulator to remotely activate gene editing. pSPN comprises a 1O2‐generating backbone grafted with polyethylenimine brushes through 1O2‐cleavable linkers. NIR photoirradiation spontaneously triggers the cleavage of gene vectors from pSPN, resulting in the release of CRISPR/Cas9 plasmids and subsequently initiating gene editing. This system affords 15‐ and 1.8‐fold enhancement in repaired gene expression relative to the nonirradiated controls in living cells and mice, respectively. As this approach does not require any specific modifications on biomolecular components, pSPN represents the first generic nanotransducer for in vivo regulation of CRISPR/Cas9 gene editing. 相似文献
78.
79.
Wei Zhang Hongbing Pan Xiaolin Lyu Dr. Kehua Gu Anqi Xiao Prof. Zhihao Shen Prof. Xing-he Fan 《Chemphyschem》2019,20(13):1759-1764
Hybrids consisting of polyhedral oligomeric silsesquioxane (POSS) and hexa-peri-hexabenzocoronene (HBC) with a dumbbell topology and C2 symmetry were designed and synthesized. They self-assemble into 5 nm ordered structures. In particular, the increased steric effect with increasing POSS units stabilizes a square columnar phase (Colsqu) which is important in nanotemplating. These hybrids containing discotic liquid crystal HBC and POSS units have an excellent etching contrast and present an approach to obtain 5 nm nanopatterns. 相似文献
80.
In this investigation we address the problem of adjoint-based optimization of PDE systems in moving domains. As an example we consider the one-dimensional heat equation with prescribed boundary temperatures and heat fluxes. We discuss two methods of deriving an adjoint system necessary to obtain a gradient of a cost functional. In the first approach we derive the adjoint system after mapping the problem to a fixed domain, whereas in the second approach we derive the adjoint directly in the moving domain by employing methods of the noncylindrical calculus. We show that the operations of transforming the system from a variable to a fixed domain and deriving the adjoint do not commute and that, while the gradient information contained in both systems is the same, the second approach results in an adjoint problem with a simpler structure which is therefore easier to implement numerically. This approach is then used to solve a moving boundary optimization problem for our model system. 相似文献