Optical nonlinearity of CdSe-PMMA hybrid nanocomposite investigated via Z-scan technique and semi-empirical relations

CdSe-PMMA nanocomposite has been synthesized by ex-situ technique. The effect of different Ag doping concentrations on its structural and optical properties has been studied. X-ray diffraction reveals the hexagonal wurtzite structure of the polymer nanocomposites with preferential growth of the nanocrystals along (1 0 0) direction. Transmission electron micrograph shows the spherical CdSe nanoparticles embedded in polymer matrix. The nonlinear refractive index of the nanocomposites has been calculated using Tichy & Ticha semi-empirical relations and Z-scan technique. Z-scan results disclose the two photon absorption process in the hybrid nanocomposites with self focussing behaviour. With Ag doping, the nonlinearity is found to be increased up to 0.2% Ag doping concentration due to the confined effect of Surface Plasmon, Quantum confinement and thermal lensing. Above 0.2% Ag concentration, its value decreases due to the declined linear refractive index of the nanocomposites. Maximum two photon figure of merit is 76 for 0.2% Ag doped CdSe-PMMA hybrid nanocomposite. The present results accentuate the possibility of tuning the optical non-linearity of CdSe-PMMA hybrid nanocomposite by adjusting the doping concentration.     

压电式纳米发电机及其混合器件的研究进展

随着化石能源的过度使用和开采,随之而来的能源和环境问题也日益尖锐,而人们对能源的需求不减反增,因此寻求一种新型的绿色可持续能源是非常必要的。环境中的能量十分丰富,因此从环境中收集能量进行转化是十分有前景的方法。压电材料在受到外界作用发生机械变形时,能实现机械能向电能的转化,因此,压电式纳米发电机作为一种潜在的可持续、绿色能源,近年来受到广泛关注。从压电材料的分类入手,结合其制备方法、结构和性能等,对近年来一些研究成果进行了概述,详细评价了不同制备方法、结构对压电式纳米发电机压电性能的影响,并对今后发展进行了展望。     

Preparation and optical limiting properties of a POSS-containing organic-inorganic hybrid nanocomposite

A novel POSS-containing organic-inorganic hybrid nanocomposite (P) was prepared by the Pt-catalyzed hydrosilylation reaction of octahydridosilsesquioxane (T₈^H) with substituted acetylene, CH≡CCH₂O-C₆H₄-COO-C₆H₄-p-NN-C₆H₄-p-OCH₃ (M). The hybrid nanocomposite was soluble in common solvents such as CHCl₃, THF, toluene and C₂H₄Cl₂. Its structure was characterized by FT-IR, ¹H NMR, and ²⁹Si NMR, respectively. Optical limiting property was evaluated by a Q-switched Nd:YAG laser system with a wavelength of 532 nm, 4 ns pulse width and a repetition of 1 Hz. The result shows that the POSS-based organic-inorganic hybrid nanocomposite exhibits novel optical limiting property, well photo and high thermal stability (T_d, temperature for 5% weight loss, as high as 319 °C). The optical limiting property increases with the increase of solution concentration.     

Thermal and optical properties of poly(methyl methacrylate)/calcium carbonate nanocomposite

The study deals with thermal and optical properties of poly(methyl methacrylate) (PMMA) containing 2wt% calcium carbonate (CaCO₃) nanofiller. It was found that the thermal conductivity increases with increasing temperatures, due to thermal activation of the phonons in the PMMA/CaCO₃ nanocomposite. This enhancement in the thermal conduction is mainly attributed to the heat transferred by lattice vibrations as major contributors and electrons as minor contributors during thermal conduction. The optical properties were investigated as a function of wavelength and photon energy of UV radiation. The optical results obtained were analysed in terms of absorption formula for noncrystalline materials. It was found that the measured optical energy gap for the pure PMMA is greater than the PMMA/CaCO₃ nanocomposite. The width of the energy tails of the localised states was calculated. Adding CaCO₃ nanofiller into PMMA matrix may cause the localised states of different colour centres to overlap and extend in the mobility gap. This overlap may give an evidence for decreasing energy gap when adding CaCO₃ nanofiller in the polymer matrix.     

纳米TiO2/醇酸复合涂层的耐腐蚀性能研究

采用盐雾试验和电化学交流阻抗技术,研究了纳米TiO2对钢板涂层耐腐蚀性能的影响,并通过扫描电镜观察了纳米TiO2复合涂层断面形貌.研究表明,纳米TiO2复合涂层的耐腐蚀性能均优于未添加纳米TiO2涂层,当纳米TiO2添加量为1.5%(质量分数)时,涂层耐盐雾时间由420h提高到710h,涂层阻抗值也由107Ω·cm2增加至109Ω·cm2.从涂层断面观察发现,纳米TiO2添加量为1.5%(质量分数)时,颗粒较均匀分散,粘接紧密,形成较为致密的纳米复合涂层.     

溶胶-凝胶法制备纳米复合永磁材料及其磁性

用溶胶-凝胶方法制备了一种新型纳米复合永磁材料.XRD及SEM表明,由于这种材料的软磁相与硬磁相具有30nm左右尺寸而发生强烈的交换耦合作用,导致该种新材料具有优异的磁性能.     

Biomimetic synthesis of hybrid nanocomposite scaffolds by freeze-thawing and freeze-drying

The aim of this study is to biomimetically synthesize hydroxyapatite-hydrophilic polymer scaffolds for biomedical applications. This organic-inorganic hybrid has been structurally characterized and reveals a good microstructural control as seen by the SEM analysis and the nanosize of the particulates is confirmed by AFM microscopy. The characterization of such nano-structured composites would allow researchers to design new systems, tailoring properties for different applications.     

聚吡咯-二氧化钛自组装复合膜的制备及其光电转换性质

通过原位自组装技术制备了聚吡咯-二氧化钛纳米复合膜,利用紫外-可见光谱、红外光谱、原子力显微镜、电化学循环伏安等方法对所制备的复合膜进行了表征.与利用原位自组装技术制备的聚吡咯膜相比较,由于在复合膜中聚吡咯和TiO2纳米粒子之间的相互作用,复合膜π→π*跃迁吸收峰发生蓝移,氧化还原峰的位置向负电位方向移动.沉积在导电玻璃ITO表面的该纳米复合膜在可见光下表现出一定的光电转换性质.     

碳纳米管/氧化镁纳米复合材料的制备和表征

以碳纳米管为模板,采取前驱物分解法合成了碳纳米管/氧化镁纳米复合材料,用XRD、IR、SEM和TG-DTG对产物进行了表征.结果表明,产物是由氧化镁均匀包裹在碳纳米管上构成的一种复合材料,管径约100nm.和碳纳米管相比,复合材料管径变粗且表面粗糙.     

Evaluation of synovium-derived mesenchymal stem cells and 3D printed nanocomposite scaffolds for tissue engineering

Abstract

Stem cells and scaffolds play a very important role in tissue engineering. Here, we isolated synovium-derived mesenchymal stem cells (SMSCs) from synovial membrane tissue and characterized stem-cell properties. Gelatin nanoparticles (NP) were prepared using a two-step desolvation method and then pre-mixed into different host matrix (silk fibroin (SF), gelatin (Gel), or SF–Gel mixture) to generate various 3D printed nanocomposite scaffolds (NP/SF, NP/SF–Gel, NP/Gel-1, and NP/Gel-2). The microstructure was examined by scanning electron microscopy. Biocompatibility assessment was performed through CCK-8 assay by coculturing with SMSCs at 1, 3, 7 and 14 days. According to the results, SMSCs are similar to other MSCs in their surface epitope expression, which are negative for CD45 and positive for CD44, CD90, and CD105. After incubation in lineage-specific medium, SMSCs could differentiate into chondrocytes, osteocytes and adipocytes. 3D printed nanocomposite scaffolds exhibited a good biocompatibility in the process of coculturing with SMSCs and had no negative effect on cell behavior. The study provides a strategy to obtain SMSCs and fabricate 3D printed nanocomposite scaffolds, the combination of which could be used for practical applications in tissue engineering.     

Evaluation of synovium-derived mesenchymal stem cells and 3D printed nanocomposite scaffolds for tissue engineering

Stem cells and scaffolds play a very important role in tissue engineering. Here, we isolated synovium-derived mesenchymal stem cells (SMSCs) from synovial membrane tissue and characterized stem-cell properties. Gelatin nanoparticles (NP) were prepared using a two-step desolvation method and then pre-mixed into different host matrix (silk fibroin (SF), gelatin (Gel), or SF–Gel mixture) to generate various 3D printed nanocomposite scaffolds (NP/SF, NP/SF–Gel, NP/Gel-1, and NP/Gel-2). The microstructure was examined by scanning electron microscopy. Biocompatibility assessment was performed through CCK-8 assay by coculturing with SMSCs at 1, 3, 7 and 14 days. According to the results, SMSCs are similar to other MSCs in their surface epitope expression, which are negative for CD45 and positive for CD44, CD90, and CD105. After incubation in lineage-specific medium, SMSCs could differentiate into chondrocytes, osteocytes and adipocytes. 3D printed nanocomposite scaffolds exhibited a good biocompatibility in the process of coculturing with SMSCs and had no negative effect on cell behavior. The study provides a strategy to obtain SMSCs and fabricate 3D printed nanocomposite scaffolds, the combination of which could be used for practical applications in tissue engineering.     

乳液插层法制备PMMA/Nd(OH)3/MMT三相纳米复合材料及表征

利用表面活性剂乳液自组装产生模板,以甲基丙烯酸甲酯(MMA)为油相,稀土离子水溶液为水相,混合形成稀土纳米粒子的反胶束微乳液,使稀土粒子均匀分散于油相中,形成热力学稳定的乳液体系,将该乳液插层于有机蒙脱土(O-MMT)的片层间,加入引发剂单体直接进行原位聚合,即制备得产物.通过红外光谱(IR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和差热-热重(TG-DTA)对该复合材料进表征和分析.研究结果表明,利用乳液法制备出热稳定性良好的新型PMMA/Nd(OH)3/ MMT三相纳米复合材料.     

Characterization and properties of TiN-containing amorphous Ti-Si-N nanocomposite coatings prepared by arc assisted middle frequency magnetron sputtering

TiN-containing amorphous Ti-Si-N (nc-TiN/a-Si₃N₄) nanocomposite coatings were deposited by using a modified closed field unbalanced middle frequency magnetron sputtering system which is arc assisted and consists of two circles of targets, at a substrate temperature of 400 °C. The coatings exhibit good mechanical properties that are greatly influenced by the total gas pressure and N₂/Ar ratios. For coatings prepared at a N₂/Ar ratio of 3:1, the hardness increases from 24 GPa at a total gas pressure of 0.2 Pa-58 GPa at 0.4 Pa, and then, the hardness decreases gradually when the total gas pressure was further increased. On the other hand, the friction coefficient decreases monotonously with increasing total gas pressure. XRD, XPS and high resolution TEM experiments showed that the coatings contain TiN nanocrystals embedded in the amorphous Si₃N₄ matrix. The coating deposited under optimum conditions exhibits excellent tribological performance with a low friction coefficient of 0.42 and a high hardness of 58 GPa. These properties make it possible for industrial applications.     

Structural engineering of vertically aligned nanocomposite films fabricated via magnetron and pulsed laser co-deposition for microwave application

Microwaves are often used in communication engineering,including in microwave relays as well as mul-tichannel,mobile,and satellite communications.To meet the demand for a\"small,light,thin,and precise\"modern electronic machine,developing highly tunable microwave materials to manufacture miniaturized microwave devices has become a top priority.Ferroelectric materials are excellent microwave materi-als,showing outstanding dielectric properties and tunability.Introducing low dielectric loss oxides in the construction of vertical self-assembly nanocomposites(VSNs)effectively improves their tunability and reduces dielectric loss.However,the optimal doping content of simple VSN films limits further improve-ment of tunability.Herein,we propose a strategy-gradient VSN to achieve combined improvement in tunability and dielectric constant by designing a sputtering and pulsed laser co-deposition.The resulting VSN composite film has a dielectric constant of 428.08,a dielectric loss of 0.0212,and a tunability of 78.69％.Our results contribute to the development of filters and have broad application prospects in the microwave industry.     

并联式混合动力电动汽车多模式能量管理策略与D2P实时仿真

针对并联式混合动力电动汽车的能量控制问题进行了研究,提出了一种多模式能量管理策略.建立了整车模型,以负载力矩、电池荷电状态(SOC)和车速作为控制依据设计了多个工作模式间的切换逻辑,将模式切换状态作为控制变量引入到力矩分配算法中,实现了多工况下对发动机与电机的优化控制.结合US06、UDDS和EUDC等工况进行了Simulink系统仿真,结果表明所提出的能量管理策略较传统功率跟随策略相比可以提高燃油经济性约1.91％,且对于不同的工况具有良好的普遍适用性;基于D2P系统构建了硬件在环仿真平台,采用真实的驾驶员输入设备和控制器进行实时仿真,进一步表明所提出的能量管理策略合理有效且算法具有良好的实时性.     

Oxygen functionalized carbon nanocomposite derived from natural illite as adsorbent for removal of cationic and anionic dyes

Oxygen functionalized carbon nanocompositse (O-I@C) based on glucose and illite were obtained through mild hydrothermal process and surface oxidation. The surface properties of the prepared O-I@C were analyzed by Boehm titration, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and Specific surface area (BET). The results showed that the surfaces of the prepared O-I@C nanocomposites were functionalized with abundant oxygen-containing functional groups (OFGs). The functionalized O-I@C nanocomposites were proven to be effective adsorbents for fast removal of congo red (CR) and methylene blue (MB) from aqueous solution within 10 min. It is demonstrated that the initial pH of dyes solution has an important influence on the adsorption process of both CR and MB, indicating that the OFGs created on the surfaces of the materials are responsible for the promoted adsorption ability. Furthermore, it is also proved that the adsorption isotherms of CR and MB obey the Langmuir model, with the maximum adsorption capacities of 238.40 mg/g and 215.28 mg/g, respectively. In addition, the used materials could be regenerated by washing with NaOH solution and reused at least four times, which exhibits potential applications as efficient and easily reusable adsorbents for the rapid removal of anionic dye CR and cationic dye MB from wastewater.     

Preparation of polymer-blended quinine nanocomposite particles by spray drying and assessment of their instrumental bitterness-masking effect using a taste sensor

Abstract

Context: The development of taste-masking technologies for foods and drugs is essential because it would enable people to consume and receive healthy and therapeutic effect without distress.

Objective: In the current study, in order to develop a novel method to prepare nanocomposite particles (microparticles containing bitter nanoparticles) in only one step, by using spray drying, a two-solution mixing nozzle-equipped spray dryer that we previously reported was used. The nanocomposite particles with or without poorly water-soluble polymers prepared using our spray-drying technique were characterized.

Methods: (1) The organic solution containing quinine, a model of bitter compound and poorly water-soluble polymers and (2) sugar alcohol (mannitol) aqueous solution were separately flown in tubes and two solutions were spray dried through two-solution type spray nozzle to prepare polymer-blended quinine nanocomposite particles. Mean diameters of nanoparticles, taste-masking effect and dissolution rate of quinine were evaluated.

Results: The results of taste masking by taste sensor suggested that the polymer (Eudragit EPO, Eudragit S100 or Ethyl cellulose)-blended quinine nanocomposite particles exhibited marked masking of instrumental quinine bitterness compared with the quinine nanocomposite particles alone. Quinine nanocomposite formulations altered the quinine dissolution rate, indicating that they can control intestinal absorption of quinine.

Conclusion: These results suggest that polymer-blended quinine composite particles prepared using our spray-drying technique are useful for masking bitter tastes in the field of food and pharmaceutical industry.     

Cuo(CoO,MnO)/SiO_2纳米复合气凝胶催化剂载体的溶胶-凝胶法制备与表征

以正硅酸乙酯(tetraethyl orthosilicate,TEOS)、乙酸铜、乙酸钴、乙酸锰为原料,采用溶胶-凝胶法、常压干燥制备了CuO(CoO,MnO)/SiO2纳米复合气凝胶.分析了过渡金属氧化物MO与Sio2的质量比、温度和pH值对凝胶形成的影响.采用场致发射扫描电镜(FE-SEM)、BET、傅里叶变换红外分析(FTIR)、热重-差热分析(TG-DTA)、电子散射能谱分析(EDS)和化学分析等对CuO(CoO,MnO)/SiO2纳米复合气凝胶的微观结构和组成进行了研究.结果表明,纳米复合气凝胶的颗粒约在20～100nm,比表面积为344～733m2/g,孔径范围为2～22nm,而且过渡金属Cu、Co和Mn能够与氧形成部分一O-M-O-桥键连接,并与Si通过化学键形成三维网络结构;纳米复合气凝胶试样中的多元过渡金属氧化物含量可控制在3%～75%(质量分数).这种结构和组成既有利于提高催化剂负载量,又可充分发挥过渡金属氧化物的助催化作用.