交联剂改性小麦醇溶蛋白/壳聚糖复合膜的制备与性能

分别以戊二醛、L-半胱氨酸为交联剂,以甘油为增塑剂,采用溶液浇铸法制备了交联小麦醇溶蛋白/壳聚糖(60/40w/w)复合膜,考察了交联剂用量对复合膜力学性能、吸湿与溶解性的影响。结果表明,以上两种交联改性可显著提高复合膜的拉伸强度与杨氏模量,40%RH下,0.15wt%戊二醛使复合膜拉伸强度提升近3倍,杨氏模量增大约8倍;戊二醛交联可降低复合膜的溶解度,而L-半胱氨酸则使复合膜的溶解度有所增加。     

乙二醛交联对明胶/PVA可生物降解复合膜性能的影响

采用流延成型法制备明胶/聚乙烯醇(Gel/PVA)复合膜,并以乙二醛为交联剂通过溶液交联法制备乙二醛交联的Gel/PVA复合膜,采用红外光谱(FTIR)、X-射线衍射(XRD)、差示扫描量热(DSC)、热重(TG)等表征交联前后复合膜的结构与性能,研究了交联剂用量对Gel/PVA复合膜力学性能及溶解性能的影响。结果表明,随着乙二醛用量的增加,Gel/PVA复合膜的拉伸强度呈先增加后逐渐降低的趋势,而断裂伸长率和溶解率则逐渐降低;乙二醛交联可提高复合膜的熔融温度及热稳定性;乙二醛交联显著影响Gel/PVA复合膜中分子间的氢键和化学结构。     

明胶/壳聚糖复合膜的制备与表征

采用流延法制备了明胶/壳聚糖复合膜,通过对复合膜结构及力学、热学、光学等性能进行表征,探究了壳聚糖对复合膜性能的影响。结果表明:明胶与壳聚糖共混相容性较好,复合膜均一透明。通过添加壳聚糖和甘油可以明显改善明胶/壳聚糖复合膜的抗拉强度、断裂伸长率、热稳定性及吸水性能;随壳聚糖含量的增加,透明度下降,壳聚糖添加量为30%(质量分数)时,透明度为79.4%(透光率小于80%)。研究认为通过壳聚糖与甘油对明胶进行改性可以不同程度地改善明胶膜的力学性能、吸水性能,能够满足其在不同领域的应用。     

聚乙烯醇/壳聚糖/明胶水凝胶的合成及其对苯酚的吸附研究

以聚乙烯醇(PVA)、壳聚糖和明胶为原料、戊二醛为交联剂,在酸性溶液中通过共混交联反应合成了聚乙烯醇/壳聚糖/明胶水凝胶,单因素法讨论了影响水凝胶性能的因素如:反应物质量比、交联剂用量、反应温度、反应时间等聚乙烯醇/壳聚糖/明胶水凝胶,对不同浓度苯酚溶液的吸附研究.研究结果表明聚乙烯醇/壳聚糖/明胶水凝胶对苯酚有较好的吸附性能.     

明胶-壳聚糖/纳米SiO_2原位载药复合膜的制备及性能研究

利用明胶、壳聚糖和纳米SiO_2,制备了明胶-壳聚糖/纳米SiO_2复合膜,对复合膜的溶胀性、机械强度等进行测试。然后将明胶-壳聚糖/纳米SiO_2复合膜用于阿司匹林的原位负载,研究纳米SiO_2用量和模型药物阿司匹林用量对原位载药复合膜缓释性能的影响。结果表明,纳米SiO_2的引入能够降低复合膜在水中的溶胀性,提高复合膜的机械强度;随着纳米SiO_2用量的增加,复合膜原位负载阿司匹林的缓释效果增加;阿司匹林用量为0.5%时,明胶-壳聚糖/纳米SiO_2原位载药复合膜具有较好的缓释效果。     

戊二醛改性壳聚糖/ 纳米TiO2 复合膜的抗水性研究

采用戊二醛作为交联剂与壳聚糖进行交联,以提高壳聚糖/ 纳米TiO2 膜的抗水性。采用三元二次通用旋转组合设计实验方法,建立了力学性能、吸水率与戊二醛用量、交联时间、TiO2 溶胶添加量的二次回归数学模型,得出了制备戊二醛改性壳聚糖/ 纳米TiO2 膜的最佳工艺条件为交联剂用量0. 10 g/ (100 mL)乙酸溶液,交联时间4. 37 h,TiO2 溶胶添加量0. 08 mL/ (100 mL)的乙酸溶液。上述条件下得到的膜的拉伸强度为5. 69MPa,吸水率为133. 66%。与壳聚糖/ 纳米TiO2 膜相比,吸水率下降了72. 8%。     

降解壳聚糖/明胶复合微球的制备及其对活性染料吸附性能研究

以降解壳聚糖、明胶为原料,戊二醛等试剂为交联剂,采用反相悬浮交联法制备出一系列具有高效吸附解吸功能的球形复合吸附材料降解壳聚糖/明胶复合微球,通过扫描电子显微镜,研究了原料种类以及搅拌速度对微球粒径与形貌的影响,将其用于活性染料印染废水处理中,研究了吸附温度、吸附时间、降解壳聚糖的用量及吸附液pH的大小对活性染料吸附性能的影响。结果表明:制得的降解壳聚糖/明胶复合微球的球粒径小,形态圆整,在温度为30℃、吸附时间为40min、溶液pH=4、微球制备时降解壳聚糖用量为0.4g、降解壳聚糖∶明胶质量配合比为1∶1条件下,降解壳聚糖/明胶复合微球球对活性黑WM的吸附容量达到137.25mg/g,并具有较好的循环使用价值。     

聚乙二醇对明胶/壳聚糖复合膜性能的影响

采用流延成型法制备了不同用量聚乙二醇200(PEG200)和聚乙二醇800(PEG800)增塑的明胶/壳聚糖复合膜,研究了PEG对明胶/壳聚糖复合膜吸湿性能、透水汽性和拉伸性能的影响,用X射线衍射(XRD)法分析了复合膜的结晶行为。结果表明,PEG的种类和用量会影响明胶/壳聚糖复合膜的结构和性能。在水活度较低时,PEG会降低复合膜的初始吸湿速率和吸湿能力;水活度较高时,PEG会提高复合膜的初始吸湿速率和吸湿能力。PEG能降低明胶/壳聚糖复合膜的单分子层吸附值和拉伸强度,增大复合膜的透水汽性、断裂伸长率及结晶度。     

PVA/PVAm改性涤纶滤布复合膜的制备及其抗污染性能

利用聚乙烯醇(PVA)和聚乙烯胺(PVAm)的混合溶液,经刮膜、干燥和交联固定化处理,改性廉价涤纶滤布制备复合膜.亲水性PVA的羟基和PVAm的氨基被用来提高复合膜的亲水性和抗污染能力.考察了改性涤纶制备复合膜过程中PVA/PVAm共混比例、交联时间、交联剂用量、涂膜厚度以及涂膜次数对复合膜抗污染性能和渗透通量的影响.结果表明:当m(PVA)∶m(PVAm)=1∶1、交联时间为45min、交联剂质量分数为0.2%、涂膜厚度为100μm且涂膜交联2次制备的复合膜的抗污染性能最好.     

交联剂对玉米淀粉醋酸酯/PVA可降解复合膜性能的影响

制备了低酯化度玉米淀粉醋酸酯(SA)(DS<0.2)/聚乙烯醇(PVA)可降解复合膜,重点讨论了交联剂的种类、用量、交联反应温度及时间对复合膜力学性能和耐水性的影响。并利用扫描电镜(SEM)X射线衍射(XRD)、热重分析(TG),对复合膜的形貌、结晶度、热稳定性进行表征。结果表明:经过交联后的复合膜,致密性提高,结晶度降低,热稳定性有所增强,表现出更好的力学性能和耐水性。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.     

Core-current-enhanced domain-wall pinning in nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon

We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.