Preparation and characterization of hybrid ZnO/ormosils films

Hybrid ZnO/ormosils Elms are prepared by the sol-gel method. A FT-IR spectrometer, 900 UV/VIS/NIR spectrophotometer, atomic force microscope, and ellipsometer are employed to investigate microstructure and optical properties of the films fired at different temperatures. The results show that the films with high transmittance and low surface roughness could be obtained at the heat-treatment temperature of 150 degrees C, the refractive index and thickness of the film are 1.413, 2.11 mu m, respectively. Higher temperatures (350 degrees C, 550 degrees C) change the Elm microstructure severely, and then decrease the transmittance of the films.

熔制条件对铋酸盐玻璃性质的影响

采用传统的玻璃熔融法制备了组成为60Bi2O3-20B2O3-15SiO2-5La2O3(mol%)的铋酸盐玻璃， 系统研究了不同工艺过程对玻璃性能的影响. 分析了样品ICP的成分，扫描电镜，X-射线衍射谱， 差热分析和紫外-可见-近红外透过光谱测试. 结果表明：使用刚玉坩埚能提高玻璃的抗析晶稳定性 和透过率，陶瓷坩埚和白金坩埚均受到严重腐蚀，玻璃组分也随之发生很大变化. 当熔制温度从1 100 ℃变化到1 300 ℃时，玻璃的颜色从浅黄色变到深红棕色. 尤其是白金粒子被腐蚀进入玻璃液 后，玻璃中很容易形成纳米颗粒或者团聚形成胶体粒子，在玻璃中形成色散源，加深玻璃的颜色， 降低透过率. 1 300 ℃下，白金粒子起到晶核剂的作用，生成Bi2Pt2O7和BiB3O6晶相，导致玻璃失透.

Epitaxial growth of ZnO films on (100) and (001) gamma-LiAlO2 substrates by pulsed laser deposition

Structural and optical properties were investigated for ZnO films grown on (100) and (001) gamma-LiAlO2 (LAO) substrates by pulsed laser deposition method. According XRD results, it is intuitionistic that (100) LAO is suitable for fabricating high quality ZnO film, while (001) LAO is unsuitable. The FWHM of XRD, stress in film and FWHM of UV PL spectra for ZnO films on (100) LAO show a decreasing with increasing substrate temperature from 300 to 600 degrees C. ZnO film fabricated at 600 degrees C has the greatest grain size, the smallest stress (0.47 Gpa) and PL FWHM value (similar to 85 meV). This means that the substrate temperature of 600 degrees C is optimum for ZnO film deposited on (100) LAO. Moreover, it was found that the UV PL spectra intensity of ZnO film is not only related to the grain size and stoichiometric, but also depends on the stress in the film.

M(C6H16N3)2(VO3)4 as heterogeneous catalysts. Study of three new hybrid vanadates of cobalt(II), nickel(II) and copper(II) with 1-(2-aminoethyl)piperazonium.

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Degradação de corantes têxteis ácidos e reativos por fotocatálise heterogênea, usando TiO2 como fotocatalisador

A indústria têxtil tem como característica a geração de grandes volumes de resíduos, principalmente corantes oriundos do tingimento de fios e tecidos. Os tratamentos convencionais de efluentes têxteis são ineficazes na degradação da maioria dos corantes. A fotocatálise heterogênea vem surgindo como alternativa promissora no tratamento desses poluentes. Neste trabalho, estudou-se a degradação fotocatalítica de duas soluções, simuladas em laboratório, compostas pelos corantes ácidos Blue 74, Red 51 e Yellow 3 (efluente I) e pelos reativos Black 5, Red 239 e Yellow 17 (efluente II), além de outros produtos químicos. Testes preliminares foram realizados para otimizar o pH e a massa de catalisador (TiO2) utilizados. Além da fotocatálise, experimentos de fotólise e adsorção também foram realizados. Através de espectrofotometria UV-VIS, verificou-se um descoramento por fotocatálise de 96% em 240 min e 97% em 30 min dos efluentes I e II, respectivamente. A mineralização do efluente I foi baixa (37%) e a do efluente II desprezível, nos tempos utilizados. No banho com corantes ácidos, foram realizadas ainda análises de toxicidade com sementes de alface (Lactuca sativa). A CE50 inicial estimada foi igual a 19,28 %, sendo a toxicidade totalmente removida após 63 min de processo fotocatalítico. A fotólise não obteve a mesma eficiência da fotocatálise, mostrando a importância do catalisador na degradação. A adsorção não foi significativa para os efluentes estudados. As cinéticas de degradação fotocatalítica de todos os corantes seguiram um modelo de pseudo-primeira ordem

Avaliação in vitro de duas resinas macias para reembasamento de próteses modificadas pela incorporação de clorexidina

Resinas macias para reembasamento de próteses são largamente utilizadas após cirurgias para estabilizarem a prótese e condicionarem o tecido, aguardando a completa cicatrização. É importante que o material não seja facilmente colonizado por biofilme oral e se possível, evite a contaminação do sítio cirúrgico. Objetivou-se avaliar o efeito da incorporação de clorexidina às resinas acrílicas macias para o reembasamento de próteses totais, através de análises de liberação, citotoxicidade e efeito inibitório de um biofilme de C. albicans. Foram confeccionados corpos de provas (CDPs) com as resinas Trusoft e Coe-soft, com incorporação de 0%, 0,5%, 1,0% e 2,0% de clorexidina, totalizando 8 grupos. A liberação de clorexidina foi avaliada através da mensuração da mudança na densidade óptica da solução de armazenamento, na qual ficaram imersos os CDPs, por espectrometria UV, a cada 48 horas, durante 40 dias. A citotoxicidade celular foi avaliada em fibroblastos (linhagem L929), que ficaram 24 horas em contato com meio de cultura no qual os CDPs ficaram previamente imersos, pela técnica de absorção de corante vermelho neutro após 24, 48 e 72 horas e semanalmente até o 28 dia. E, por fim, a atividade antifúngica contra a C. albicans (ATCC 10231) foi avaliada de duas maneiras: (1) teste de difusão em ágar, no qual os CDPs foram colocados em placas de BHI previamente inoculadas com C. albicans, com medição do halo de inibição após 48 horas de incubação a 37C; (2) a avaliação da inibição da formação de um biofilme de C. albicans sobre a superfície dos CDPs pela quantificação por metil tetrazólio (MTT) a cada 48 horas, durante 22 dias, com leitura feita em espectrofotômetro de UV. Os dados obtidos foram inseridos no programa SigmaStat (versão 3.1, USA) para realizar as análises estatísticas. As diferenças estatísticas foram determinadas por análises de variâncias do tipo ANOVA e todos os procedimentos para comparações múltiplas pareadas foram feitos utilizando-se o método Holm-Sidak, com nível de significância global igual a 0,05. A clorexidina adicionada às resinas testadas foi capaz de ser liberada para o meio de armazenagem, proporcionalmente à quantidade de clorexidina incorporada, porém com diferentes cinéticas de liberação entre as resinas, visto que a Trusoft libera até 71% do total de clorexidina liberada nas primeiras 48 horas e a Coe-soft, até 44%. Ambas as resinas com incorporação de clorexidina apresentaram efeito citotóxico adicional, se comparadas às resinas sem clorexidina, porém para a Coe-soft não houve diferença estatística dos valores, apenas para a Trusoft (p<0,001). Ocorreu formação de halo de inibição proporcionalmente às concentrações de resinas adicionadas, com maiores halos para a resina Trusoft (p<0,001), e sem formação de halo para as resinas sem clorexidina; a inibição da formação de biofilme, realizada somente com a resina Coe-soft, mostrou total inibição durante 8, 12 e 16 dias, para a incorporação de 0,5%, 1,0% e 2,0% respectivamente, sendo uma diminuição estatisticamente significativa (p<0,001) em relação à resina sem incorporação de clorexidina, que não apresentou inibição do biofilme.

土地利用变化对西双版纳地区土壤及植被碳含量的影响

土地利用变化，尤其是热带地区森林生态系统土地利用方式的变化极大地改变了全球碳循环，对大气CO2浓度的升高，气候变暖等全球性环境问题起着不可忽视的作用。同时，森林的大面积破坏，引起土壤流失，营养元素含量降低，土壤健康状况恶化，最终大幅度降低生态系统的生产力。本文主要结合野外实地调查和室内分析的方法，研究森林砍伐后转变为农田和橡胶园对西双版纳热带地区土壤碳、氮、磷含量以及有机质化学结构的影响，天然次生林恢复、橡胶园建设对大气CO2的蓄积作用。 森林砍伐后转变为农田和橡胶园，显著地改变了土壤的理化特性。研究结果表明，与次生林相比，农田和橡胶园表层土壤容重、pH值升高，含水量降低，有机质、全氮、全磷、速效氮、有效磷含量显著降低。土地利用变化对土壤特性的影响主要发生在0-40 cm 表层土壤，而对40 cm以下土层影响较小。 土地利用变化改变土壤碳含量，同时影响土壤有机质的化学结构。胡敏酸紫外-可见光谱(UV-VIS)、傅利叶变换红外光谱 (FT-IR) 分析发现，不同生态系统表层土壤 (0-20 cm) 胡敏酸光谱学特性存在明显差异。次生林E4/E6值高于农田和橡胶园。与次生林相比，农田和橡胶园表层土壤有机质中酚基相对含量显著降低，脂肪族、芳香族、羧基以及多聚糖等化合物相对含量增加。 运用样地调查、生物量模型模拟和室内土壤样品分析方法，研究了次生林恢复和橡胶园建设对大气CO2的汇集作用。结果表明：退化土壤恢复为次生林、农田建设橡胶园能够有效促进植被和土壤中碳的汇集。次生林和橡胶林生物量增长速率分别为9.8，10.2 （9.4）t•ha-1•yr-1, 1 m表层土壤有机碳汇集速率分别为0.7和1.1 t•C•ha-1•yr-1。模拟结果显示，40年橡胶林生物量为327 (324) t•ha-1, 恢复50年后天然次生林生物量为395 t•ha-1。加之土壤有机碳，40年橡胶园约汇集碳190 t•ha-1, 次生林恢复50年碳汇集潜力为250 t•ha-1。

The morphology of decorated amyloid fibers is controlled by the conformation and position of the displayed protein.

Self-assembled structures capable of mediating electron transfer are an attractive scientific and technological goal. Therefore, systematic variants of SH3-Cytochrome b(562) fusion proteins were designed to make amyloid fibers displaying heme-b(562) electron transfer complexes. TEM and AFM data show that fiber morphology responds systematically to placement of b(562) within the fusion proteins. UV-vis spectroscopy shows that, for the fusion proteins under test, only half the fiber-borne b(562) binds heme with high affinity. Cofactor binding also improves the AFM imaging properties and changes the fiber morphology through changes in cytochrome conformation. Systematic observations and measurements of fiber geometry suggest that longitudinal registry of subfilaments within the fiber, mediated by the interaction and conformation of the displayed proteins and their interaction with surfaces, gives rise to the observed morphologies, including defects and kinks. Of most interest is the role of small molecule modulation of fiber structure and mechanical stability. A minimum complexity model is proposed to capture and explain the fiber morphology in the light of these results. Understanding the complex interplay between these factors will enable a fiber design that supports longitudinal electron transfer.

A highly conductive and transparent solution processed AZO/MWCNT nanocomposite

A solution processed aluminum-doped zinc oxide (AZO)/multi-walled carbon nanotube (MWCNT) nanocomposite thin film has been developed offering simultaneously high optical transparency and low electrical resistivity, with a conductivity figure of merit (σDC/σopt) of ~75-better than PEDOT:PSS and many graphene derivatives. The reduction in sheet resistance of thin films of pristine MWCNTs is attributed to an increase in the conduction pathways within the sol-gel derived AZO matrix and reduced inter-MWCNT contact resistance. Films have been extensively characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffractometry (XRD), photoluminescence (PL), and ultraviolet-visible (UV-vis) spectroscopy. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Controlled amine functionality in self-assembled monolayers via the hidden amine route: chemical and electronic tunability.

A synthetic strategy for fabricating a dense amine functionalized self-assembled monolayer (SAM) on hydroxylated surfaces is presented. The assembly steps are monitored by X-ray photoelectron spectroscopy, Fourier transform infrared- attenuated total reflection, atomic force microscopy, variable angle spectroscopic ellipsometry, UV-vis surface spectroscopy, contact angle wettability, and contact potential difference measurements. The method applies alkylbromide-trichlorosilane for the fabrication of the SAM followed by surface transformation of the bromine moiety to amine by a two-step procedure: S(N)2 reaction that introduces the hidden amine, phthalimide, followed by the removal of the protecting group and exposing the free amine. The use of phthalimide moiety in the process enabled monitoring the substitution reaction rate on the surface (by absorption spectroscopy) and showed first-order kinetics. The simplicity of the process, nonharsh reagents, and short reaction time allow the use of such SAMs in molecular nanoelectronics applications, where complete control of the used SAM is needed. The different molecular dipole of each step of the process, which is verified by DFT calculations, supports the use of these SAMs as means to tune the electronic properties of semiconductors and for better synergism between SAMs and standard microelectronics processes and devices.

Photodegradation of 2-naphthol in aqueous solutions in the presence of humic acid and ferric ions

In this work, the photodegradation of the carcinogenic pollutant 2-naphthol in aqueous solution containing Aldrich humic acid (HA) and ferric ions (Fe(III)) under 125 W and 250 W high pressure mercury lamp (HPML, lambda >= 365 nm) irradiation was investigated. The photooxidation efficiencies were dependent on the pH values, light intensities and Fe(III)/HA concentration in the water, with higher efficiency at pHs 3-4, and 50 mu mol l(-1) Fe(III) with 20 mg l(-1) HA under 250 W HPML. The initial rate of photooxidation increases with increasing, the initial concentration of 2-naphthol from 10 mu mol l(-1) to 100 mu mol l(-1), while do not change at 50 and 100 mu mol l(-1). However, higher removal efficiency of 2-naphthol is achieved at its lower initial concentration of 10 mu mol l(-1), and initial rate of photooxidation is 0.193 mu mol l(-1) min(-1). Dissolved oxygen (DO) plays an important role in the system containing Fe(III)-HA complexes in which Fenton and photo-Fenton reactions were enhanced in the environment. Hydroxyl radicals produced in HA solution with or without ferric ions were determined by using benzene as free radical scavenger and phenol as scavenging products proportional to hydroxyl radicals. By using UV-Vis and excited fluorescence spectrum techniques, the main photooxidation products, which have higher absorption in the region of 240-340 nm, were found, and the mechanisms for the oxidative degradation is proposed.

Impacts of hydrogen dilution on growth and optical properties of a-SiC : H films

Hydrogenated amorphous silicon-carbon (a-SiC:H) films were deposited by plasma enhanced chemical vapor deposition (PECVD) with a fixed methane to silane ratio ([CH4]/[SiH4]) of 1.2 and a wide range of hydrogen dilution (R-H=[H-2]/[SiH4 + CH4]) values of 12, 22, 33, 102 and 135. The impacts of RH on the structural and optical properties of the films were investigated by using UV-VIS transmission, Fourier transform infrared (FTIR) absorption, Raman scattering and photoluminescence (PL) measurements. The effects of high temperature annealing on the films were also probed. It is found that with increasing hydrogen dilution, the optical band gap increases, and the PL peak blueshifts from similar to1.43 to 1.62 eV. In annealed state, the room temperature PL peak for the low R-H samples disappears, while the PL peak for the high R-H samples appears at similar to 2.08 eV, which is attributed to nanocrystalline Si particles confined by Si-C and Si-O bonds.

NIP a-Si : H solar cells on stanless steel with p-type nc-Si : H window layer

The successful application of boron-doped hydrogenated nanocrystalline silicon as window layer in a-Si: H nip solar cells on stainless steel foil with a thickness of 0.05 mm is reported. Open circuit voltage and fill factor of the fabricated solar cell were 0.90V and 0.70 respectively. The optical and structural properties of the p-layers have been investigated by using UV-VIS and Raman spectroscopy. It is confirmed that the p-layer is hydrogenated nanocrystalline silicon with a wide optical gap due to quantum size effect.

Effect of dopant concentration on photocatalytic activity of TiO2 film doped by Mn non-uniformly

The thin films of TiO2 doped by Mn non-uniformly were prepared by sol-gel method under process control. In our preceding study, we investigated in detail, the effect of doping mode on the photocatalytic activity of TiO2 films showing that Mn non-uniform doping can greatly enhance the activity. In this study we looked at the effect of doping concentration on the photocatalytic activity of the TiO2 films. In this paper, the thin films were characterized by UV-vis spectrophotometer and electrochemical workstation. The activity of the photocatalyst was also evaluated by photocatalytic degradation rate of aqueous methyl orange under UV radiation. The results illustrate that the TiO2 thin film doped by Mn non-uniformly at the optimal dopant concentration (0.7 at %) is of the highest activity, and on the contrary, the activity of those doped uniformly is decreased. As a comparison, in 80 min, the degradation rate of methyl orange is 62 %, 12 % and 34 % for Mn non-uniform doping film (0.7 at %), the uniform doping film (0.7 at %) and pure titanium dioxide film, respectively. We have seen that, for the doping and the pure TiO2 films, the stronger signals of open circuit potential and transient photocurrent, the better photocatalytic activity. We also discusse the effect of dopant concentration on the photocatalytic activity of the TiO2 films in terms of effective separation of the photon-generated carriers in the semiconductor. (C) Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved.

Photochromic diarylethene for reversible holographic recording

A novel photochromic, diarylethene with 2,5-dihydrothiophene bridging unit la was synthesized, and the photochromic properties of 1 were also investigated. It showed that I exhibited excellent ring-open and ring-closed photochromism with UV/vis light irradiation. Holographic recording was measured by employing the thin film of PMMA-diarylethene 1 as recording media. It showed that six different images were recorded in the same place on the sample with the dimension of 64 mu m x 42 mu m by the intersecting of the object beam and a reference beam with an intensity of 15 mW/cm(2), and the stored information was readout by the attenuated reference beam with an intensity of 0.5 mW/cm(2). In addition, preliminary investigations showed that the material was thermally stable and fatigue resistant. (C) 2007 Elsevier B.V. All rights reserved.