Creation of calcite hollow microspheres with attached bundles of aragonite needles

Novel calcite hollow microspheres attached with bundles of aragonite needles have been synthesized via a simple precipitation reaction of aqueous solutions of CaClB_2B and NaB_2BCOB_3B in the presence of MgP^2+P ions at room temperature. The experimental results revealed that an appropriate molar ratio of [MgP^2+P]/[CaP^2+P], pH value of the solution and aging time are crucial for the formation of the unusual hierarchical CaCOB_3B superstructure. A possible growth mechanism is proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation,Microstructure and Photocatalytic Activity of the Porous TiO2 Anatase Coating by Sol-Gel Processing

In this study the porous TiO² anatase coatings are prepared from alkoxide solutions containing polyethylene glycol (PEG) by a dip-coating technique. The effects of PEG addition to the precursor solution on the photocatalytic activity and microstructure of the resultant coatings are studied. The larger amount and the larger molecular weight of PEG, the larger size and more pores produced in the resultant coatings on the decomposition of PEG during heat-treatment. The adsorbed hydroxyl content of such porous coatings is found to increase due to the larger size and more pores in the coatings. However, the transmittance of the coatings decreases due to the scattering by the larger size and more pores. Photocatalytic degradation experiments show that organophosphorous insecticide, dimethyl-2,2-dichlorovinyl phosphate (DDVP), was efficiently degraded in the presence of the porous TiO₂ coatings by exposing the DDVP solution to sunlight. Photocatalytic degradation rate was related to the adsorbed hydroxyl content, transmittance and morphology of the resultant coatings.     

Photocatalytic TiO2/glass nanoflake array films

A new approach for the fabrication of oriented TiO2/glass nanoflake arrays has been developed. The ceramic nanoflake array was formed on a glass substrate via a simple, low temperature, and one-step hydrothermally induced phase separation approach without using any templates or additives. The factors affecting the formation of ceramic nanoflakes were examined by various characterization techniques. The results showed that the leaching of the soluble phase from the glass surface through hydrothermal processes resulted in oriented uniform ceramic nanoflake arrays. Electron microscope observations revealed that the nanoflakes formed a continuous porous three-dimensional-network array with a large surface-to-volume ratio. In addition, an anatase TiO2 film was successfully coated onto the nanoflake array by the sol-gel method. The TiO2/glass nanoflake array exhibited high activity for the photocatalytic degradation of acetone and for photoinduced hydrophilic conversion. Such enhancements were attributed to the beneficial effects of the new continuous porous three-dimensional-interconnected nanoflake network and its surface geometrical nanostructure. The present approach provides a convenient route to modify a photocatalytic coating with a porous nano-architectured substrate. This opens extensive new opportunities in the design of semiconductor/ceramic nanostructural array thin films with unusual properties for future optical and electronic applications.     

Preparation and characterization of highly photoactive nanocrystalline TiO_2 powders by solvent evaporation- induced crystallization method

Highly photoactive bi-phase nanocrystalline TiO2 photocatalyst was prepared by a solvent evaporation-induced crystallization (SEIC) method, and calcined at different temperatures. The obtained TiO2 photocatalyst was characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results show that solvent evaporation can promote the crystallization and phase transformation of TiO2 at 100℃. When calcination temperatures are below 600℃, the prepared TiO2 powders show bimodal pore size distributions in the mesoporous region. At 700℃, the pore size distributions exhibit monomodal distribution of the inter-aggregated pores due to the collapse of the intra-aggregated pores. At 100℃, the obtained TiO2 photocatalyst by this method shows good photocatalytic activity, and at 400℃, its photocatalytic activity exceeds that of Degussa P25. This may be attributed to the fact t     

Atomic Force Microscopic Studies of Porous TiO2 Thin Films Prepared by the Sol-Gel Method

Porous titanium dioxide thin films were prepared from alkoxide solutions with and without polyethylene glycol (PEG) by the sol-gel method on soda-lime glass. The effects of PEG addition to the precursor solution on the microstructure and roughness of the resultant thin films were investigated by atomic force microscopy (AFM). It was found that TiO₂ films prepared from the precursor solution without PEG had granular microstructure and flat texture, and was composed of about 100 nm spherical particles. With an increase in the times of coating cycles, the roughness of films decreased and the size of TiO₂ particles increased. On the other hand, the larger the amount and molecular weight of the added PEG in precursor solutions, the larger the diameter and the depth of pores in the resultant films on the decomposition of PEG during heat-treatment. The surface of the films was also rougher, and fewer pores were produced during heat-treatment. The mechanism of porous structure formation in the TiO₂ films was explained using the principle of spinodal phase separation.     

Photocatalytic Activity and Characterization of the Sol-Gel Derived Pb-Doped TiO2 Thin Films

Photocatalytically active Pb-doped TiO₂ thin films were prepared on a soda-lime glass substrate by sol-gel dip-coating technique using TiO₂ sols containing lead(II) nitrate. The thin films were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), UV-VIS spectroscopy and X-ray diffraction (XRD). A shift of the UV-VIS absorption towards longer wavelengths was observed, which indicated a decrease in the band-gap of TiO₂ upon Pb doping. XRD results showed both pure and Pb-doped TiO₂ thin films were polycrystalline, anatase type, and oriented predominantly to the (101) plane. A slight shift in the d-spacing for the Pb-doped film indicated the incorporation of Pb into the TiO₂ lattice to form Pb _x Ti_1–x O₂ solid solution. AFM results showed Pb-doped TiO₂ thin films were composed of larger TiO₂ particles and had rougher surface, compared with un-doped TiO₂ thin films. XPS results showed that except for the enrichment of Pb near the surface, Pb exists in the forms of Pb _x Ti_1–x O₂ and PbO. Dimethyl-2,2-dichlorovinyl phosphate (DDVP) was efficiently degraded in the presence of the Pb-doped TiO₂ thin films by exposing the insecticide solution to sunlight. The mechanism of photocatalytic activity enhancement of the Pb-doped TiO₂ thin films was discussed.     

一种飞行器电缆插接状态自动化检测方法

新一代飞行器的电气系统越来越复杂,依靠主观识别方法检测电缆插接状态,人工失误轻则烧毁星上设备,重则导致任务失败。提出一种飞行器电缆插接状态自动化检测方法,通过插接状态检测编码和信号变换设计,确保检测电路占用尽量少的电连接器资源和背板资源;通过信号走线优化设计,避免检测电路增加电缆分支数,降低电缆加工和敷设成本;通过电源走线优化设计,确保测试电路与星上电路隔离。本文方法无需飞行器加电即可自动检测电缆插错、漏插等问题,提高了飞行器综合测试的安全性和可靠性。     

Activatable Semiconducting Polymer Pro-nanomodulators for Deep-Tissue Sono-immunotherapy of Orthotopic Pancreatic Cancer

Immunotherapy has provided a promising modality for cancer treatment, while it often has the issues of limited response rates and potential off-target side effects in clinical practice. We herein report the construction of semiconducting polymer pro-nanomodulators (SPpMs) with ultrasound (US)-mediated activatable pharmacological actions for deep-tissue sono-immunotherapy of orthotopic pancreatic cancer. Such SPpMs consist of a sonodynamic semiconducting polymer backbone grafted with poly(ethylene glycol) chains linked with two immunomodulators (a programmed death-ligand 1 blocker and an indoleamine 2,3-dioxygenase inhibitor) via a singlet oxygen (¹O₂)-cleavable segment. In view of the excellent sonodynamic property of the semiconducting polymer core, SPpMs enable effective generation of ¹O₂ under US treatment, even in a deep-tissue depth up to 12 cm. The generated ¹O₂ not only ablates tumors via a sonodynamic effect and induces immunogenic cell death, but also destroys the ¹O₂-cleavable segments to allow in situ release of immunomodulators in tumors. This synergetic action results in boosted antitumor immune response via reversing two tumor immunosuppressive pathways. As such, SPpMs mediate deep-tissue sono-immunotherapy to completely eradicate orthotopic pancreatic cancer and effectively prevent tumor metastasis. Moreover, such an immune activation reduces the possibility of immune-related adverse events. This study thus provides a smart activatable nanoplatform for precise immunotherapy of deep-seated tumors.     

Dye-sensitized solar cells based on ordered titanate nanotube films fabricated by electrophoretic deposition method

Dye-sensitized solar cells (DSSCs) are fabricated based on ordered titanate nanotube (TNT) films obtained by electrophoretic deposition (EPD) method. Calcination temperatures show a great influence on the performance of TNT solar cells. At 300 °C, the cells exhibit very low photo-electric conversion efficiency. At 400 °C, the efficiency obviously increases. At 600 °C, the cells show the highest efficiency, which is higher than the efficiency of the cells made from commercial-grade Degussa P25 TiO₂ nanoparticles (P25).     

Graphene-based semiconductor photocatalysts

Graphene, a single layer of graphite, possesses a unique two-dimensional structure, high conductivity, superior electron mobility and extremely high specific surface area, and can be produced on a large scale at low cost. Thus, it has been regarded as an important component for making various functional composite materials. Especially, graphene-based semiconductor photocatalysts have attracted extensive attention because of their usefulness in environmental and energy applications. This critical review summarizes the recent progress in the design and fabrication of graphene-based semiconductor photocatalysts via various strategies including in situ growth, solution mixing, hydrothermal and/or solvothermal methods. Furthermore, the photocatalytic properties of the resulting graphene-based composite systems are also discussed in relation to the environmental and energy applications such as photocatalytic degradation of pollutants, photocatalytic hydrogen generation and photocatalytic disinfection. This critical review ends with a summary and some perspectives on the challenges and new directions in this emerging area of research (158 references).