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101.
Nan Zhang Tao Bing Xiangjun Liu Cui Qi Luyao Shen Linlin Wang Dihua Shangguan 《Chemical science》2015,6(7):3831-3838
Guanine-rich oligonucleotides (GROs) have attracted considerable attention as anticancer agents, because they exhibit cancer-selective antiproliferative activity and can form G-quadruplex structures with higher nuclease resistance and cellular uptake. Recently, a GRO, AS1411 has reached phase II clinical trials for acute myeloid leukemia and renal cell carcinoma. The antiproliferative activity of GROs has been associated with various protein targets; however the real mechanisms of action remain unclear. In this study, we showed evidence that antiproliferative activity of GROs (including AS1411) is mainly contributed by the cytotoxicity of their guanine-based degradation products, such as monophosphate deoxyguanosine (dGMP), deoxyguanosine (dG) and guanine. The GROs with lower nuclease resistance exhibited higher antiproliferative activity. Among nucleotides, nucleosides and nucleobases, only guanine-based compounds showed highly concentration-dependent cytotoxicity. Our results suggest that it is necessary to reconsider the cancer-selective antiproliferative activity of GROs. Since guanine-based compounds are endogenous substances in living organisms, systematic studies of the cytotoxicity of these compounds will provide new information for the understanding of certain diseases and offer useful information for drug design. 相似文献
102.
Tingting Zhang Wanying Lei Ping Liu José A. Rodriguez Jiaguo Yu Yang Qi Gang Liu Minghua Liu 《Chemical science》2015,6(7):4118-4123
Structure–function correlations are a central theme in heterogeneous (photo)catalysis. In this study, the geometric and electronic structure of perovskite ferroelectric KNbO3 nanowires with respective orthorhombic and monoclinic polymorphs have been systematically addressed. By virtue of aberration-corrected scanning transmission electron microscopy, we directly visualize surface photocatalytic active sites, measure local atomic displacements at an accuracy of several picometers, and quantify ferroelectric polarization combined with first-principles calculations. The photoreactivity of the as-prepared KNbO3 nanowires is assessed toward aqueous rhodamine B degradation under UV light. A synergy between the ferroelectric polarization and electronic structure in photoreactivity enhancement is uncovered, which accounts for the prominent reactivity order: orthorhombic > monoclinic. Additionally, by identifying new photocatalytic products, rhodamine B degradation pathways involving N-deethylation and conjugated structure cleavage are proposed. Our findings not only provide new insights into the structure–photoreactivity relationships in perovskite ferroelectric photocatalysts, but also have broad implications in perovskite-based water splitting and photovoltaics, among others. 相似文献
103.
Lei Wang Man Zhang Ying‐Ying Jin Qing Lu Qi Fang 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(1):69-74
Three 1‐phenylindolin‐2‐one derivatives, namely 1‐phenylindolin‐2‐one, C14H11NO, (I), 5‐bromo‐1‐phenylindolin‐2‐one, C14H10BrNO, (II), and 5‐iodo‐1‐phenylindolin‐2‐one, C14H10INO, (III), have been synthesized and their structures determined. Compounds (I) and (II) crystallized in the centrosymmetric space groups Pbca and P21/c, respectively, while compound (III) crystallized in the polar space group Aea2. Density functional theory (DFT) calculations show that the molecular dipole moment gradually decreases in the order (I) > (II) > (III). The relatively smaller dipole moment of (III) and the larger non‐electrostatic intermolecular interactions may be the main reasons for the noncentrosymmetric and polar structure of (III). 相似文献
104.
Haibin Chen Zheng-Hai Huang Liqun Qi 《Journal of Optimization Theory and Applications》2017,174(3):746-761
A symmetric tensor is called copositive if it generates a multivariate form taking nonnegative values over the nonnegative orthant. Copositive tensors have found important applications in polynomial optimization, tensor complementarity problems and vacuum stability of a general scalar potential. In this paper, we consider copositivity detection of tensors from both theoretical and computational points of view. After giving several necessary conditions for copositive tensors, we propose several new criteria for copositive tensors based on the representation of the multivariate form in barycentric coordinates with respect to the standard simplex and simplicial partitions. It is verified that, as the partition gets finer and finer, the concerned conditions eventually capture all strictly copositive tensors. Based on the obtained theoretical results with the help of simplicial partitions, we propose a numerical method to judge whether a tensor is copositive or not. The preliminary numerical results confirm our theoretical findings. 相似文献
105.
Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility.Thus charge transport anisotropy along different directions is commonly observed in organic semiconductors.Interestingly,in this article,we found that comparable charge transport property were achieved based on the single crystals of a bis-fused tetrathiafulvalene derivative(EM-TTP) compound along two interaction directions,that is,the multiple strong S…S intermolecular interactions and the π-π stacking direction,with the measured electrical conductivity and hole mobility of 0.4 S cm~(-1),0.94 cm~2 V~(-1) s~(-1) and 0.2 S cm~(-1),0.65 cm2 V~(-1) s~(-1),respectively.This finding provides us a new molecular design concept for developing novel organic semiconductors with isotropic charge transport property through the synergistic effect of multiple intermolecular interactions(such as S…S interactions) and π-π stacking. 相似文献
106.
Jingwei Wang Qianqian Luo Chunhua Luo Hechun Lin Ruijuan Qi Ni Zhong Hui Peng 《Journal of Solid State Electrochemistry》2017,21(7):2071-2077
In this study, MoS2 nanosheets were first prepared by exfoliating its bulk material in HCl/LiNO3 solution with a yield of 45%, and then a facile strategy was developed to synthesize polyaniline/MoS2 (PANI/MoS2) nanocomposite via in situ polymerization. Structural and morphological characterizations of MoS2 nanosheets and the nanocomposite were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray powder diffraction. The results of SEM illustrated that orderly sawtooth polyaniline (PANI) nanoarrays were formed on the surface of MoS2 nanosheets. The nanocomposite displayed good electrochemical performance as a supercapacitor electrode material. The specific capacitance reached 560 F/g at a current density of 1.0 A g?1 in 1.0 M H2SO4 solution. Such good performance is because that the MoS2 nanosheets provided a highly electrolytic accessible surface area for redox-active PANI and a direct path for electrons. 相似文献
107.
Changping Wang Prof. Qiang Zhang Xinyu Wang Hong Chang Prof. Sanjun Zhang Yuankai Tang Prof. Jianhua Xu Ruijuan Qi Prof. Yiyun Cheng 《Angewandte Chemie (International ed. in English)》2017,56(24):6767-6772
Engineering near-infrared (NIR) light-sensitive enzymes remains a huge challenge. A photothermal effect-associated method is developed for tailoring the enzymatic activity of enzymes by exposure to NIR light. An ultrasmall platinum nanoparticle was anchored in an enzyme to generate local heating upon NIR irradiation, which enhanced the enzyme activity without increasing bulk temperature. Following NIR irradiation, the enzyme activity was tailored rapidly and reversibly, and was modulated by varying laser power density and irradiation time. Four enzymes were engineered, including glucoamylase, glucose oxidase, catalase, and proteinase K with NIR-light sensitivity, and demonstrated their utility in practical applications such as photolithography and NIR light-responsive antibacterial or anticancer actions. Our investigation suggests that this approach could be broadly used to engineer enzymes with NIR-light sensitivity for many biological applications. 相似文献
108.
Construction of Renewable Superhydrophobic Surfaces via Thermally Induced Phase Separation and Mechanical Peeling 下载免费PDF全文
We report a simple preparation method of a renewable superhydrophobic surface by ther-mally induced phase separation (TIPS) and mechanical peeling. Porous polyvinylidene fluo-ride (PVDF) membranes with hierarchical structures were prepared by a TIPS process under different cooling conditions, which were confirmed by scanning electron microscopy and mer-cury intrusion porosimetry. After peeling off the top layer, rough structures with hundreds of nanometers to several microns were obtained. A digital microscopy determines that the surface roughness of peeled PVDF membranes is much higher than that of the original PVDF membrane, which is important to obtain the superhydrophobicity. Water contact angle and sliding angle measurements demonstrate that the peeled membrane surfaces display super-hydrophobicity with a high contact angle (152°) and a low sliding angle (7.2°). Moreover, the superhydrophobicity can be easily recovered for many times by a simple mechanical peel-ing, identical to the original superhydrophobicity. This simple preparation method is low cost, and suitable for large-scale industrialization, which may offer more opportunities for practical applications. 相似文献
109.
Existence and limit behavior of prescribed L2‐norm solutions for Schrödinger‐Poisson‐Slater systems in
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In this paper, we study constraint minimizers of the following L 2?critical minimization problem: where E (u ) is the Schrödinger‐Poisson‐Slater functional and N denotes the mass of the particles in the Schrödinger‐Poisson‐Slater system. We prove that e (N ) admits minimizers for and, however, no minimizers for N >N ?, where Q (x ) is the unique positive solution of in . Some results on the existence and nonexistence of minimizers for e (N ?) are also established. Further, when e (N ?) does not admit minimizers, the limit behavior of minimizers as N ↗N ? is also analyzed rigorously. 相似文献
110.
Feng Qi 《Proceedings Mathematical Sciences》2017,127(4):551-564
In this paper, we present derivatives of the generating functions for the Bell numbers by induction and by the Faà di Bruno formula, recover an explicit formula in terms of the Stirling numbers of the second kind, find the (logarithmically) absolute and complete monotonicity of the generating functions, and construct some inequalities for the Bell numbers. From these inequalities, we derive the logarithmic convexity of the sequence of the Bell numbers. 相似文献