基于样本库的人脸图像处理方法

本文给出了一种基于样本库的人脸图像超分辨率方法,这一方法结合了人脸图像全局相似性和局部特征相似性的约束.局部结构的相似性将超分辨率解约束到人脸局部结构空间,不同尺度上的局部相似性指导搜索最优解,然后将局部结构重建的人脸图像投影到由人脸图像确定的特征人脸空间.实验结果表明该算法得到的人脸具有很好的准确性和视觉效果.     

Understanding the barriers to crystal growth: dynamical simulation of the dissolution and growth of urea from aqueous solution

Both the dissolution and growth of a molecular crystalline material, urea, has been studied using dynamical atomistic simulation. The kinetic steps of dissolution and growth are clearly identified, and the activation energies for each possible step are calculated. Our molecular dynamics simulations indicate that crystal growth on the [001] face is characterized by a nucleation and growth mechanism. Nucleation on the [001] urea crystal face is predicted to occur at a very high rate, followed by rapid propagation of the steps. The rate-limiting step for crystallization is actually found to be the removal of surface defects, rather than the initial formation of the next surface layer. Through kinetic Monte Carlo modeling of the surface growth, it is found that this crystal face evolves via a rough surface topography, rather than a clean layer-by-layer mechanism.     

2-呋喃甲酰腙衍生物的合成、荧光性质及抑菌活性

以2-呋喃甲醛、苯甲酰肼及其衍生物为原料,合成了4个新型呋喃酰腙（4a~4d）,用溶剂挥发法获得了酰腙4a的单晶,并用X射线单晶衍射仪测定了晶体和分子结构。 通过元素分析、核磁共振、红外光谱、紫外光谱和荧光光谱等技术手段对酰腙（4a~4d）进行了表征。 结构分析表明,酰腙4a通过分子间氢键和分子间呋喃环错位面对面π…π作用力构成二维链式层状结构;荧光分析表明,酰腙4c拥有较强的荧光发射。 采用琼脂扩散法测试了酰腙（4a~4d）对大肠杆菌、金黄色葡萄球菌、绿脓杆菌的抑制活性,结果显示,酰腙4c对金黄色葡萄球菌有显著的抑制活性。     

酸碱度调控氧化锌纳米材料形貌及其光催化还原CO2研究

利用水热法合成了形貌可控的氧化锌(ZnO)微纳材料。利用X射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM),紫外-可见(UV-Vis)分光光谱和比表面积分析(BET)等技术对所制备的ZnO材料进行了表征。不同酸碱度(pH值)条件下,经过500 ℃退火2 h制备的ZnO均为纤锌矿结构。随着前驱液pH值的增加,所得ZnO从片状晶体变为棒状晶体。片状ZnO主要暴露极性晶面,棒状ZnO主要暴露非极性晶面。从生长角度考虑,在溶液为弱酸性条件下(pH 6.5),溶液中游离的氯离子(Cl^-)抑制了ZnO在锌极性面({Zn²⁺}_{crystal surface})的生长,水热反应产物为片状Zn₅(OH)₈Cl₂·H₂O,退火后得到微孔片状ZnO;当溶液中添加氢氧根(OH^-)后,锌离子(Zn²⁺)被络合为四羟基锌络合离子(Zn(OH)₄^2-),该络离子促进了ZnO在{Zn²⁺}_{crystal surface}的生长,从而得到棒状晶体。利用上述催化剂,在氙灯照射下进行光催化还原二氧化碳实验,发现极性面较多的片状ZnO具有更高的光催化性能。     

Electron beam curable coating for marble

Natural marble is, in general, characterized by graceful aspect, fine texture and hard property. However, it has a trend to produce staining and to lose its glossy face with white powdering when exposed to the outdoor environment. This study deals with a method for prevention of the deterioration of marble by application of an electron beam curable acrylic clear coating of nonsolvent type. It is proved that the method is effective for the minimization of the deterioration of marble.     

Polydipropylsiloxane Single Crystals

Polydipropylsiloxane single crystals, grown from a dilute n-butylacetate solution, were characterized by electron microscopy and by selected-area electron-beam diffraction techniques. The electron diffraction study shows that the growth face was parallel to the (100) plane. Fracture of single crystals parallel to the fold plane takes place during the electron diffraction examination to give ribbon like lamellae about 300 A wide and 80 A thick. Fracture normal to the fold plane was also observed.     

Preparation and Characterization of Pt/Co‐Core Au‐Shell Magnetic Nanoparticles

Pt/Co‐core Au‐shell nanoparticles were synthesized via a two‐step route using NaBH₄ as a reducing agent. The nanoparticles are characterized by UV‐vis spectroscopy, transmission electron microscopy (TEM) and powder X‐ray diffraction (XRD). The results indicate that the as‐synthesized Pt/Co‐core Au‐shell nanoparticles have a disordered face centered cubic (fcc) structure, whereas the annealed Pt/Co‐core Au‐shell nanoparticles exhibit an ordered face centered tetragonal (fct) structure. Superconducting quantum interference device (SQUID) studies reveal that the coercivity of the annealed Pt/Co‐core Au‐shell nanoparticles increases to 510 Oe after heat treatment at 500 °C for 2 h.     

A Novel Two‐Dimensional Cadmium Polymeric Aminonaphthalene Sulfonate and its Application in the Synthesis of CdS Materials

A new mixed‐ligand complex, [CdL(bipy)(CH₃OH)(NO₃)]_n ( 1 ), (HL = 4‐amino‐1‐naphthalene sulfonic acid and bipy = 4,4′‐bipyridine) could be achieved by combining d¹⁰ Cd²⁺ to HL and bridging ligand 4,4′‐bipy. The structure is characterized by X‐ray single‐crystal diffraction. 4‐amino‐1‐naphthalene sulfonate and 4,4′‐bipyridine act as bridging ligands, linking two adjacent Cd^II atom to form a two‐dimensional coordination polymer, respectively. N‐H···O hydrogen‐bonding interaction between these networks to form the face‐to‐face three‐dimensional architecture. By carrying out the reaction of polymeric cadmium naphthalene sulfonate with Na₂S in the presence of sodium hydroxide, scalelike CdS materials have been obtained. The structure has been characterized by scanning electron microscopy and powder X‐ray diffraction.     

Synthesis,Characterization, and Structure of Some 1,4‐Disubstituted Cyclopenta[d][1,2]oxazines

Oxazine‐based chemistry offers an alternative to thiophene and pyrrole semiconductors and has been largely unexplored for electronics applications. Discrete monomers or oxazine polymers could serve as an efficient hole carrier for novel devices. A series of 1,4‐disubstituted cyclopenta[d ][1,2]oxazines (R = tolyl, p‐nitrophenyl, t‐buytl, furyl, and 5‐methylthienyl) were isolated via ring closure with hydroxylamine from a 1,2‐acylcyclopentadiene precursor. The target oxazines were characterized by NMR and IR spectroscopy and direct analysis in real time (DART) MS. Single‐crystal x‐ray structure determination confirmed the identity of the tolyl oxazine, which shows a face‐to‐face stacking pattern of the heterocyclic rings.     

Preparation of PANI/PSF conductive composite films and their characteristic

Polyaniline (PANI)/polysulfone (PSF) composite films are successfully prepared by phase separation and one-step in-situ polymerization. It is found that the head-on face (in contact with solution) of the films is green while the back face is white. The chemical component and the surface morphology of both surfaces of the films are characterized by FT-IR spectra and SEM, respectively. The effect of the polymerization temperature, time and concentration of the reactants on the electrical properties of the films are discussed in details. The thermo-oxidative degradation of the films is studied by thermogravimetric analysis (TGA). The results indicate that the thermal stability of the PANI/PSF films is higher than that of the pure PSF film. __________ Translated from Journal of Northwest Normal University (Natural Science), 2005, 39(11) (in Chinese)     

Structure of inorganic–organic hybrid polymer assembled by mercury(II) iodide and sulfur-rich compound

The metal complex, [Hg₂I₄(PEDT)]_∞ (1), PEDT=4,5-(phenyl-ethylenedithio)-1,3-dithiole-2-thione, has been synthesized and characterized by single crystal X-ray diffraction. It is found to be an unusual organic–inorganic hybrid structure. The inorganic layer is composed of chains of Hg with bridging I, in one case doubly bridged and in the other singly, interconnected by further bridging I to complete the two dimensional connectivity. The organic layers contain pairs of centrosymmetrically related, and therefore head to tail, face to face molecules. Each molecule of such a pair participates in the formation of short SS contacts with a molecule of a centrosymmetrically related neighboring molecule pair thus creating chains of molecules. The connectivity within the organic layer is completed by C–Hπ contacts between the chains. Connectivity between the organic and inorganic layers is achieved by participation of the thione S in the coordination of one type of Hg.     

催化剂载体对硼氢化钠在纳米金电极上电氧化行为的影响

分别以中孔炭(MPC)和VXC-72R炭黑作载体,制备了中孔炭载纳米Au粒子(Au/MPC)和VXC-72R炭黑载纳米Au粒子(Au/CB),并将其用作直接硼氢化钠燃料电池阳极电氧化催化剂.分别用X-射线衍射(XRD)、透射电镜(TEM)等比较了不同载体催化剂的结构和形貌.结果表明,纳米Au粒子均为面心立方结构,Au/MPC中纳米Au粒子的粒径为16nm左右比Au/CB中的纳米Au粒子的更小,且均匀分散在载体的表面.用循环伏安曲线和动电位极化曲线等比较了不同载体催化剂的电化学特性.结果表明,Au/CB的电流密度为38.10mA·cm-2,而Au/MPC的电流密度达到42.88mA·cm-2,比Au/CB的电流密度提高了12.5%.     

Electrochemical characterization of PANI-Nafion membranes and their electrocatalytic activity

PANI-Nafion^® membranes were prepared by a chemical method in which the faces of a commercial Nafion membrane were contacted with two acid solutions containing an oxidant (Fe³⁺) and aniline respectively. They were then characterized by a variety of electrochemical techniques (cyclic voltammetry, chronoamperometry, ac impedance). PANI was stored mostly in the vicinity of the Nafion face exposed to the oxidant. When this face was contacted with Hg and the other with electrolyte solutions, typical electrochemical responses of PANI were detected. Electrocatalytic reduction of O₂ and oxidation of N₂H₄ were achieved on PANI-Nafion electrodes and found to be only slightly slowed down with respect to ordinary PANI film electrodes, at variance with a fast process such as Fe³⁺ reduction, the rate of which was severely limited by diffusion through the membrane.     

Technetium dichloride: a new binary halide containing metal-metal multiple bonds

Technetium dichloride has been discovered. It was synthesized from the elements and characterized by several physical techniques, including single crystal X-ray diffraction. In the solid state, technetium dichloride exhibits a new structure type consisting of infinite chains of face sharing [Tc(2)Cl(8)] rectangular prisms that are packed in a commensurate supercell. The metal-metal separation in the prisms is 2.127(2) ?, a distance consistent with the presence of a Tc≡Tc triple bond that is also supported by electronic structure calculations.     

Natural and Conventional Cosmetics—Mercury Exposure Assessment

Mercury (Hg) can enter the human body through the respiratory tract and digestive system, but also through the skin. Sources of Hg in the environment can be natural processes, but also human activities, including agriculture, chemical, and pharmaceutical industries. Hg can also enter the body through food, but also with cosmetics that are used for a long time. Therefore, the aim of this study was to evaluate the Hg content in 268 randomly selected cosmetics: Natural and conventional, for face and body. Hg content was determined using an atomic absorption spectrometer (AMA 254, Leco, Prague, Czech Republic). It was shown that the face preparations were characterized by a significantly higher Hg content than the body preparations. No differences in the content of the tested element were found between natural and conventional preparations. Hg could be detected in all samples with concentrations measured from 0.348 to 37.768 µg/kg.     

Janus-AT bases: synthesis, self-assembly, and solid state structures

The high yielding synthesis of heterocycles with defined H-bond accepting and donating capabilities provides for the design of self-assembling structures and specific recognition of biological targets. Herein we report the syntheses and solid-state structures of three self-complementary uracil/thymine derivatives where each presents the standard ADA face inherently complementary to adenine and a synthetically appended DAD face complementary to uracil/thymine. These heterocycles, which have never before been reported or characterized, represent diaminopurine-uracil/thymine hybrids that, in two of the three cases, relate to previously reported heterocyclic hybrids of G and C. All three heterocycles crystallized to afford the first X-ray crystal structures of self-complementary heterocycles capable of ADA-DAD pairing. The potential use in DNA and RNA recognition are briefly discussed.     

Uranyl–Peroxide Capsule Self-Assembly in Slow Motion

Uranyl-peroxide capsules are the newest family of polyoxometalates. Although discovered 13 years previously with over 70 topologies reported, there is a lack in the fundamental understanding of assembly mechanisms, particularly the role of the alkali counterions. Herein, the reaction pathway and assembly of uranyl peroxide capsules is reported by tracking the conversion from K⁺ uranyl triperoxide monomer to the K⁺ uranyl-peroxide U₂₈ capsule by means of small-angle X-ray scattering and Raman spectroscopy. For the first time, the K⁺ uranyl-peroxide pentamer face is isolated and structurally characterized, giving credence to the long-held belief that these geometric faces serve as building blocks to the fully formed capsules. Once isolated and re-dissolved, the pentamer face undergoes rapid conversion to capsule forms, underlining its high reactivity that challenges its isolation. Calorimetric measurements of the studied species confirms the pentamer lies on the energy landscape between the monomer and capsule.     

Remote NADH imaging through an ordered array of electrochemiluminescent nanoapertures

In this report, we present an ordered array comprising thousands of nanoapertures for the electrochemiluminescent (ECL) detection of NADH. It was fabricated on the distal face of a coherent optical fiber bundle. Such a high-density array of nanoapertures combines optical, imaging and electrochemical properties. Indeed, each nanoaperture is surrounded by a gold nanoring, which acts as an electrode material. The behavior of the array was characterized by cyclic voltammetry and it shows excellent electrochemical performances. NADH is the analyte, which is measured in presence of Ru(bpy)3(2+). The ruthenium complex mediates the NADH oxidation and this coenzyme acts as a co-reactant in the ECL mechanism. ECL light is generated at the distal face of the array by each gold ring electrode. A fraction of this ECL light is collected by the corresponding nanoaperture, transmitted through the optical fiber bundle and finally imaged on the proximal face with a CCD camera. In this work, we show that NADH concentration is remotely detected by an oxidative-reductive ECL mechanism. We present also some preliminary results about the ECL process of NADH with Ru(bpy)3(2+). The ECL behavior of NADH on gold surface is reported. The influence of the applied potential on the collected light intensity was investigated. The variation of the ECL intensity measured through the nanoaperture array with NADH concentration is linear. Remote ECL detection of NADH is spatially resolved over a large area with a micrometer resolution through the array. Therefore, such array integrates several complementary functions: ECL light generation, collection, transmission and remote imaging in an array format.     

Cluster Fusion: Face‐Fused Nine‐Atom Deltahedral Clusters in [Sn14Ni(CO)]4−

The title anion was synthesized by heating dimethylformamide (DMF) solution of the known Ni‐centered and Ni(CO)‐capped tin clusters [Ni@Sn₉Ni(CO)]^3?. The new anion represents the first example of face‐fused nine‐atom molecular clusters. The two clusters are identical elongated tricapped trigonal prisms of nido‐[Sn₈Ni(CO)]^6? with nickel at one of the capping positions. They are fused along a triangular face adjacent to a trigonal prismatic base and made of two Sn and one Ni atoms. The new anion is structurally characterized by single‐crystal X‐ray diffraction in the compound (K[222‐crypt])₄[Sn₁₄Ni(CO)]?DMF. Its presence in solution is corroborated by electrospray mass spectrometry.