High-quality hydrogen from the catalyzed decomposition of formic acid by Pd-Au/C and Pd-Ag/C

Pd-Au/C and Pd-Ag/C were found to have a unique characteristic of evolving high-quality hydrogen dramatically and steadily from the catalyzed decomposition of liquid formic acid at convenient temperature, and further this was improved by the addition of CeO(2)(H(2)O)(x).     

The promotion effect of titania nanoparticles on the direct electrochemistry of lactate dehydrogenase sol-gel modified gold electrode

The promotion effect of titania nanoparticles (nano-TiO(2)) on the direct electron transfer between lactate dehydrogenase (LDH) and the silica sol-gel modified gold electrode was investigated by adding nano-TiO(2) (50 nm) in the modification process. This nano-TiO(2)-LDH electrode showed a pair of quasi-reversible cyclic voltammetry peaks with the formal potential of 70 mV (vs. SCE). Compared to the previous result of LDH modified electrode with only an irreversible cathodic peak, an anodic peak appeared and the cathodic peak potential shifted to the positive direction on this nano-TiO(2)-LDH electrode, which demonstrated that the direct electrochemistry of LDH was enhanced by nano-TiO(2). We supposed that the direct electrochemistry of LDH may be due to the redox reaction of some electroactive amino acids in the LDH molecule. The surface morphologies of electrodes characterized by SEM indicated that LDH was successfully immobilized on the sol-gel matrix and also had some interactions with nano-TiO(2). This electrode can be used as a biosensor for the determination of lactic acid. The calibration range of lactic acid was from 1.0 to 20 micromolL(-1) and the detection limit was 0.4 micromolL(-1). Meanwhile, the small K(m)(app) value (2.2 micromolL(-1)) suggested that LDH possessed high enzymatic activity and good affinity to lactic acid owing to the promotion effect of nano-TiO(2).     

Studies on the magnetism of cobalt ferrite nanocrystals synthesized by hydrothermal method

Fe-Co/CoFe₂O₄ nanocomposite and CoFe₂O₄ nanopowders were prepared by the hydrothermal method. The structure of magnetic powders were characterized by X-ray diffraction diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermal gravity analysis (TGA) and differential thermal analysis (DTA) analysis, X-ray photoelectron spectrometry (XPS), and Fourier transform infrared spectra (FTIR) techniques, while magnetic properties were determined by using a vibrating sample magnetometer (VSM) at room temperature. The effects of hydrothermal reaction conditions on magnetic properties were also discussed in details. The values of saturation magnetization (M_s) and coercive fore (H_c) for Fe-Co/CoFe₂O₄ nanocomposite are 113 emu/g and 1.4 kOe, respectively. Furthermore, CoFe₂O₄ ferrite with a single-domain critical size of 70 nm was fabricated by controlling the hydrothermal reaction conditions carefully, which presents high coercive force (ca. 4.6 kOe) and high squareness ratio (ca. 0.65). One interesting thing is M_s value of CoFe₂O₄ ferrite with a diameter of 40 nm is 86 emu/g which is comparable to that of the bulk counterpart.     

Semiconductor SERS on Colourful Substrates with Fabry-Pérot Cavities

Non-metallic materials have emerged as a new family of active substrates for surface-enhanced Raman scattering (SERS), with unique advantages over their metal counterparts. However, owing to their inefficient interaction with the incident wavelength, the Raman enhancement achieved with non-metallic materials is considerably lower with respect to the metallic ones. Herein, we propose colourful semiconductor-based SERS substrates for the first time by utilizing a Fabry-Pérot cavity, which realize a large freedom in manipulating light. Owing to the delicate adjustment of the absorption in terms of both frequency and intensity, resonant absorption can be achieved with a variety of non-metal SERS substrates, with the sensitivity further enhanced by ≈100 times. As a typical example, by introducing a Fabry-Pérot-type substrate fabricated with SiO₂/Si, a rather low detection limit of 10⁻¹⁶ M for the SARS-CoV-2S protein is achieved on SnS₂. This study provides a realistic strategy for increasing SERS sensitivity when semiconductors are employed as SERS substrates.     

Design of a Fully Non-Fused Bulk Heterojunction toward Efficient and Low-Cost Organic Photovoltaics

To modulate the miscibility between donor and acceptor materials both possessing fully non-fused ring structures, a series of electron acceptors (A4T-16, A4T-31 and A4T-32) with different polar functional substituents were synthesized and investigated. The three acceptors show good planarity, high conformational stability, complementary absorption and energy levels with the non-fused polymer donor (PTVT-BT). Among them, A4T-32 possesses the strongest polar functional group and shows the highest surface energy, which facilitates morphological modulation in the bulk heterojunction (BHJ) blend. Benefiting from the proper morphology control method, an impressive power conversion efficiency (PCE) of approaching 16.0 % and a superior fill factor over 0.795 are achieved in the PTVT-BT : A4T-32-based organic photovoltaic cells with superior photoactive materials price advantage, which represent the highest value for the cells based on the non-fused blend films. Notably, this cell maintains ≈84 % of its initial PCE after nearly 2000 h under the continuous simulated 1-sun-illumination. In addition, the flexible PTVT-BT : A4T-32-based cells were fabricated and delivered a decent PCE of 14.6 %. This work provides an effective molecular design strategy for the non-fused non-fullerene acceptors (NFAs) from the aspect of bulk morphology control in fully non-fused BHJ layers, which is crucial for their practical applications.     

Balancing the Crystallinity and Film Formation of Metal–Organic Framework Membranes through In Situ Modulation for Efficient Gas Separation

Polycrystalline metal–organic framework (MOF) layers hold great promise as molecular sieve membranes for efficient gas separation. Nevertheless, the high crystallinity tends to cause inter-crystalline defects/cracks in the nearby crystals, which makes crystalline porous materials face a great challenge in the fabrication of defect-free membranes. Herein, for the first time, we demonstrate the balance between crystallinity and film formation of MOF membrane through a facile in situ modulation strategy. Monocarboxylic acid was introduced as a modulator to regulate the crystallinity via competitive complexation and thus concomitantly control the film-forming state during membrane growth. Through adjusting the ratio of modulator acid/linker acid, an appropriate balance between this structural “trade-off” was achieved. The resulting MOF membrane with moderate crystallinity and coherent morphology exhibits molecular sieving for H₂/CO₂ separation with selectivity up to 82.5.     

A new aptameric biosensor for cocaine based on surface-enhanced Raman scattering spectroscopy

The present study reports the proof of principle of a reagentless aptameric sensor based on surface-enhanced Raman scattering (SERS) spectroscopy with "signal-on" architecture using a model target of cocaine. This new aptameric sensor is based on the conformational change of the surface-tethered aptamer on a binding target that draws a certain Raman reporter in close proximity to the SERS substrate, thereby increasing the Raman scattering signal due to the local enhancement effect of SERS. To improve the response performance, the sensor is fabricated from a cocaine-templated mixed self-assembly of a 3'-terminal tetramethylrhodamine (TMR)-labeled DNA aptamer on a silver colloid film by means of an alkanethiol moiety at the 5' end. This immobilization strategy optimizes the orientation of the aptamer on the surface and facilitates the folding on the binding target. Under optimized assay conditions, one can determine cocaine at a concentration of 1 muM, which compares favorably with analogous aptameric sensors based on electrochemical and fluorescence techniques. The sensor can be readily regenerated by being washed with a buffer. These results suggest that the SERS-based transducer might create a new dimension for future development of aptameric sensors for sensitive determination in biochemical and biomedical studies.     

Synthesis, characterization, and photovoltaic properties of a low band gap polymer based on silole-containing polythiophenes and 2,1,3-benzothiadiazole

A new low band gap silole-containing conjugated polymer, PSBTBT, was designed and synthesized. Photovoltaic properties of PSBTBT were initially investigated, and an average power conversion efficiency (PCE) of 4.7% with a best PCE of 5.1% was recorded under illumination (AM 1.5G, 100 mW/cm(2)). The response range of the device covers the whole visible range from 380 to 800 nm. These results indicate that PSBTBT is a promising polymer material for applications in polymer solar cells.     

Realizing 11.3% efficiency in fullerene-free polymer solar cells by device optimization

In this work, photovoltaic properties of the PBDB-T:ITIC based-NF-PSCs were fully optimized and characterized by tuning the morphology of the active layers and changing the device architecture. First, donor/acceptor (D/A) weight ratios were scanned, and then further optimization was performed by using different additives, i.e. 1,8-diiodooctane (DIO), diphenyl ether (DPE), 1-chloronaphthalene (CN) and N-methyl-2-pyrrolidone (NMP), on the basis of best D/A ratio (1:1, w/w), respectively. Finally, the conventional or inverted device architectures with different buffer layers were employed to fabricate NF-PSC devices, and meanwhile, the morphology of the active layers was further optimized by controlling annealing temperature and time. As a result, a record efficiency of 11.3% was achieved, which is the highest result for NF-PSCs. It’s also remarkable that the inverted NF-PSCs exhibited long-term stability, i.e. the best-performing devices maintain 83% of their initial PCEs after over 4000 h storage.     

基于广度优先搜索算法的故障隔离矩阵生成方法

相关性矩阵表示故障与测试之间的逻辑关系。隔离矩阵表示在给定的测试顺序下,故障隔离与测试之间的需求关系。测试顺序对诊断费用影响可以通过隔离矩阵进行计算。所以求解隔离矩阵是诊断费用优化的前提。针对相关性矩阵与隔离矩阵易于混淆的问题,以及传统分析方法求解隔离的不足,详述隔离矩阵的概念和生成原理,设计基于广度优先搜索的隔离矩阵生成算法。示例表明,生成算法是可行的和有效的。