断面高宽比对轮胎性能的影响

在赛车运动开始后不久,工程人员就意识到提高汽车转弯速度的方法之一是使汽车与路面产生更大的摩擦力.在早期进行的获取汽车与路面之间更大摩擦力的众多尝试中,较有趣的一种是采用双后轮行驶.然而,最有代表性的解决办法是采用胎面更宽,即断面宽度更大的轮胎.     

Fast removal of Pb(II) and Cu(II) from contaminated water by groundwater treatment waste: impact of sorbent composition

ABSTRACT

A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe₂O₃, 7.4% P₂O₅, 7.4% CaO and 5.2% SiO₂. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions.     

Plastid Transformation of Micro-Tom Tomato with a Hemipteran Double-Stranded RNA Results in RNA Interference in Multiple Insect Species

Plant-mediated RNA interference (RNAi) holds great promise for insect pest control, as plants can be transformed to produce double-stranded RNA (dsRNA) to selectively down-regulate insect genes essential for survival. For optimum potency, dsRNA can be produced in plant plastids, enabling the accumulation of unprocessed dsRNAs. However, the relative effectiveness of this strategy in inducing an RNAi response in insects using different feeding mechanisms is understudied. To investigate this, we first tested an in vitro-synthesized 189 bp dsRNA matching a highly conserved region of the v-ATPaseA gene from cotton mealybug (Phenacoccus solenopsis) on three insect species from two different orders that use leaf-chewing, lacerate-and-flush, or sap-sucking mechanisms to feed, and showed that the dsRNA significantly down-regulated the target gene. We then developed transplastomic Micro-tom tomato plants to produce the dsRNA in plant plastids and showed that the dsRNA is produced in leaf, flower, green fruit, red fruit, and roots, with the highest dsRNA levels found in the leaf. The plastid-produced dsRNA induced a significant gene down-regulation in insects using leaf-chewing and lacerate-and-flush feeding mechanisms, while sap-sucking insects were unaffected. Our results suggest that plastid-produced dsRNA can be used to control leaf-chewing and lacerate-and-flush feeding insects, but may not be useful for sap-sucking insects.     

利用太赫兹技术和统计方法鉴别地沟油

基于普通食用油和地沟油的太赫兹吸收光谱,利用0.16~1.30 THz频域的吸收谱,进行聚类分析,8种地沟油组成一类,食用油自成一类。随机选择了2种地沟油作为验证样品,将其余油样进行聚类,采用概率神经网络法对验证样品进行判定,并成功将2种油判定为地沟油。结果表明,太赫兹时域光谱技术结合统计方法可推广成为鉴别地沟油的快速有效手段。     

Highly efficient photocatalytic degradation of methylene blue using carbonaceous WO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> composites

Recent improvements in the performance of photocatalysts made it possible to tackle pollution through environment friendly methods. This study investigates the modification of the photocatalytic activity of TiO₂ by employing WO₃ and conductive polymers, namely, polyaniline (Pani) and polypyrrole (Ppy). Basing on our previous improvement of TiO₂ using a conductive polymer and activated carbon (AC), this study determines the activated carbon forms of TiO₂. The prepared composites are characterized using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, Brunauer–Emmet–Teller, and UV–Vis spectroscopy. The specific surface area of the mesoporous composites is as follows: WO₃/TiO₂·AC (Pani) > WO₃/TiO₂·AC (Ppy) > WO₃/TiO₂·Pani > WO₃/TiO₂·Ppy (127 > 98 > 68 > 44 m² g^?1), which exhibited a similar trend to the photocatalytic performances (100 > 95 > 91 > 72 % conversion rate). This result could be attributed to higher porosity, surge of charge separation, and photo-responding range extension induced by the synergistic effect of WO₃, conducting polymers, and TiO₂ in the samples.     

A Review on the Radioprotective Activity of organogermanium and Organosilicon Compounds

The present review describes the work carried out during the last 20 years in the field of the radioprotective activity and toxicity of several classes of organosilicon and organogermanium compounds (i.e. metallathiazolidines, metalladithioacetals, metallatranes and germathianes).     

Hydrophilicity improvement of silicone rubber by interpenetrating polymer network formation in the proximal layer of polymer surface

A novel method composed of an interpenetrating polymer network (IPN) formation reaction in aqueous solution was developed to improve the hydrophilicity of silicone rubber (SR) substrate. This solution phase method is compatible, simple, and convenient for some sensitive biomedical applications of SR devices because of using water as reaction solvent instead of harmful chemicals. In this work, a sequential interpenetrating polymer network formation in the proximal layer of SR surface, using poly(2-hydroxyethyl methacrylate) (PHEMA), as the second network was conducted so that led to actually surface modification resulting in an improved hydrophilicity. The modified surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), contact angle measurement, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) to assess the wettability, chemical composition and morphology of the surface modified PDMS. The results indicated that the surface modification method offered a novel and facile approach to improve the hydrophilicity of SR without altering its bulk properties. This method could be suitable for biomedical applications because of using water as a monomer solvent and polymerization medium.     

Neural-network-based modeling and optimization of the electro-discharge machining process

In this research, a new integrated neural-network-based approach is presented for the prediction and optimal selection of process parameters in die sinking electro-discharge machining (EDM) with a flat electrode (planing mode). A 3–6–4–2-size back-propagation neural network is developed to establish the process model. The current (I), period of pulses (T), and source voltage (V) are selected as network inputs. The material removal rate (MRR) and surface roughness (Ra) are the output parameters of the model. Experimental data were used for training and testing the network. The results indicate that the neural model can predict process performance with reasonable accuracy, under varying machining conditions. The effects of variations of the input machining parameters on process performance are then investigated and analyzed through the network model. Having established the process model, a second network, which parallelizes the augmented Lagrange multiplier (ALM) algorithm, determines the corresponding optimum machining conditions by maximizing the MRR subject to appropriate operating and prescribed Ra constraints. The optimization procedure is carried out in each level of the machining regimes, such as finishing (Ra≤2 μm), semi-finishing (Ra≤4.5 μm), and roughing (Ra≤7 μm), from which, the optimal machining parameter settings are obtained. The optimization results have also been discussed, verified experimentally, and the amounts of relative errors calculated. The errors are all in acceptable ranges, which, again, confirm the feasibility and effectiveness of the adopted approach.     

Optimization of Supercritical Extraction of Linalyl Acetate from Lavender via Box‐Behnken Design

Essential oil was extracted from lavender using supercritical carbon dioxide by means of a newly developed periodic static‐dynamic (PSD) procedure and the conventional semicontinuous (SC) technique. Applying GC‐FID analysis in conjunction with Box‐Behnken design, an optimum overall extraction yield (94.4 %) was obtained via PSD in contrast to 90 % for the SC method. The results indicate that supercritical fluid extraction is a viable technique for separation of constituents such as linalyl acetate, linalool, fenchone, and camphor for pharmaceutical and medicinal applications. Furthermore, a substantial reduction of energy consumption and solvent consumption is achieved with the developed PSD process compared to the conventional SC method.     

The Binding of Anionic Dyes by Cross-Linked Cationic Starches

Adsorption of anionic dyes on the cross-linked with epichlorohydrin starches containing quaternary ammonium groups (CCS) was investigated and compared with that of modified starches containing only quaternary ammonium groups (CS). The adsorption of anionic dyes on CS and CCS closely follows the Langmuir model of adsorption. The computed Langmuir saturation capacity Q _o increases with increasing degree of substitution (DS) of CS or CCS and has the value from 0.81 mol/kg to 3.22 mol/kg for CCS and from 0.88 mol/kg to 1.87 mol/kg for CS. The effectiveness of the cationic groups in dye binding was about 1 mol/equiv for CSS with DS from 0.47 to 0.62 and all the cationic groups had attached one anionic groups of the dye. Increasing DS of CS decreases the effectiveness of dye binding due to the increase in solubility of CS, and the soluble part of CS binds the dye as a typical soluble polyelectrolyte. CCS are more suitable than CS for the anionic dye adsorption from a textile dyeing solution. DS of CCS should be about 0.5–0.6. They adsorb the anionic dyes in few minutes and acts in the wide range of pH of the solutions. The Langmuir saturation capacity Q _o and the effectiveness of the cationic groups in dye binding increase with an increase of the adsorption temperature. The positive values of the enthalpy and entropy suggest that the adsorption is endothermic and during the adsorption of the anionic dye on CCS the randomness of the system increases.