Synthesis and properties of cinnamic acid series organic UV ray absorbents–interleaved layered double hydroxides

Organic ultraviolet (UV) ray absorbents, cinnamic acid (CA) and p-methoxycinnamic acid (PMOCA) were intercalated into Zn₂Al layered double hydroxides (Zn₂Al-LDHs) by co-precipitation reaction. The organic–inorganic nanocomposites, Zn₂Al-LDH/CA and Zn₂Al-LDH/PMOCA were obtained. The samples showed excellent UV ray absorption ability and their catalytic activity for the air oxidation of castor oil greatly decreased when the organic UV ray absorbents were intercalated in the layers of the Zn₂Al-LDHs. The studies suggested that Zn₂Al-LDH/organic UV absorbent nanocomposites might be used as safe sunscreen materials.     

The influence of ply sequence and thermoelastic stress field on asymmetric delamination crack growth behavior of embedded elliptical delaminations in laminated FRP composites

The influence of ply lay up and the interaction of residual thermal stresses and mechanical loading on the interlaminar asymmetric embedded delamination crack growth behavior have been investigated. Two sets of full three-dimensional thermo-elastic finite element analyses have been performed for the interlaminar elliptical delaminations, which may be due to manufacturing defects or other reasons and are located symmetrically with respect to the midplane in a quasi-isotropic FRP composite laminate lay up. Depending upon the through-the-thickness location of the embedded elliptical delaminations, four different laminate configurations have been considered. Strain energy release rate (SERR) procedures have been employed to assess the delamination crack growth characteristics at the interfaces. It is found that the individual fracture modes exhibit asymmetric and non self-similar crack growth behavior along the delamination front depending upon the location of the interfacial delaminations; ply sequence and orientation and thermo-elastic anisotropy of the laminae.     

Development of a small DMFC bipolar plate stack for portable applications

The direct methanol fuel cell (DMFC) is regarded as a promising candidate in portable electronic power applications. Bipolar plate stacks were systematically studied by controlling the operating conditions, and by adjusting the stack structure design parameters, to develop more commercial DMFCs. The findings indicate that the peak power of the stack is influenced more strongly by the flow rate of air than by that of the methanol solution. Notably, the stack performance remains constant even as the channel depth is decreased from 1.0 to 0.6 mm, without loss of the performance in each cell. Furthermore, the specific power density of the stack was increased greatly from ∼60 to ∼100 W l⁻¹ for stacks of 10 and 18 cells, respectively. The current status of the work indicates that the power output of an 18-cell short stack reaches 33 W in air at 70 °C. The outer dimensions of this 18-cell short stack are only 80 mm × 80 mm × 51 mm, which are suitable for practical applications in 10–20 W DMFC portable systems.     

Research on better use of wood for sustainable development: Quantitative evaluation of good tactile warmth of wood

Wood is a prospective material against the problems of mineral resource shortage and global warming from the viewpoint of sustainable development. The continuous cycle of felling, planting and growing of trees is essential prerequisite for sustainability. The engineering evaluation of advantages of wood can increase its use more widely as a substitute for other industrial materials and save the finite mineral resources. The increase of wood use can support the continuous cycle for the sustainable forestry as an industry. This paper treats good tactile warmth of wood as one of its advantages. The relationship between contact surface temperature and thermal effusivity is derived from the theoretical analysis of governing heat transfer phenomenon on tactile warmth. Some knowledge on tactile warmth of wood is reviewed with these physical properties. The sensory tactile warmth of wood has a high and positive linear correlation with the logarithm of the contact surface temperature. The materials with lower thermal effusivity feel warmer than the ones with higher thermal effusivity. The relationship between contact surface temperature and thermal effusivity explains rationally why each wood has a large difference of tactile warmth in spite of their small difference of material properties. It also explains the reason why wood has good tactile warmth regardless of seasons against metals, which feel too hot in summer and too cold in winter to touch. The contact surface temperature and the thermal effusivity are proposed as engineering measures to evaluate the tactile warmth of wood and other materials.     

Resistance to sulfidation of the catalytic reduction of NOx over Ag/Al2O3 by controlling the loadings of Ag and Ag+

SO₂ strongly decreased the catalytic activities of low loading Ag/Al₂O₃ below 500 °C in selective catalytic reduction (SCR) of NO_x by propene with or without the assistance of non-thermal plasma (NTP), which was mainly attributed to the competition between SO₂ and NO. By controlling the loadings of Ag and Ag⁺ over alumina, the resistance of SO₂ was remarkably enhanced between 400 °C and 500 °C in thermal SCR. In the NTP-assisted SCR, most of the NO_x conversions were also apparently recovered from 250 °C to 500 °C.     

Fault gear identification and classification using discrete wavelet transform and adaptive neuro-fuzzy inference

In this paper, an intelligent diagnosis for fault gear identification and classification based on vibration signal using discrete wavelet transform and adaptive neuro-fuzzy inference system (ANFIS) is presented. The discrete wavelet transform (DWT) technique plays one of the important roles for signal feature extraction in the proposed system. The abnormal transient signals will show in different decomposition levels and can be used to recognize the various faults by the DWT figure. However, many fault conditions are hard to inspect accurately by the naked eye. In the present study, the feature extraction method based on discrete wavelet transform with energy spectrum is proposed. The different order wavelets are considered to identify fault features accurately. The database is established by feature vectors of energy spectrum which are used as input pattern in the training and identification process. Furthermore, the ANFIS is proposed to identify and classify the fault gear positions and the gear fault conditions in the fault diagnosis system. The proposed ANFIS includes both the fuzzy logic qualitative approximation and the adaptive neural network capability. The experimental results verified that the proposed ANFIS has more possibilities in fault gear identification. The ANFIS achieved an accuracy identification rate which was more satisfactory than traditional vision inspection in the proposed system.     

Low-voltage cathodoluminescent properties of ZnGa2O4:Mn phosphors coated with In2O3 nano-particles

Change in the low-voltage luminescence properties of ZnGa₂O₄:Mn green phosphors before and after In₂O₃-coating was examined by cathodoluminescence. The coating state and distribution of In₂O₃ nano-particles on phosphors were investigated by field emission scanning electron microscopy (FE-SEM). Especially, based on FE-SEM analysis, the formation of In₂O₃ nano-particles on ZnGa₂O₄:Mn phosphor was confirmed. The improvement of the cathodoluminescence efficiency and lifetime in the In₂O₃-coated phosphors was associated with the coating of In₂O₃ nano-particles.     

Efficiency of acetic acid and formic acid as a catalyst in catalytical and mechanocatalytical pretreatment of barley straw

In this study, the potential of organic acids (formic acid, acetic acid) in a catalytical and mechanocatalytic conversion of lignocellulosic barley straw to valuable sugars is explored using sulfuric acid as a reference. Acid-catalyzed hydrolysis has been carried out with acid-impregnated samples as well as unmodified barley straw. In the mechanocatalytical approach, pretreatment consists of impregnation with the acid catalyst and mechanical treatment by ball milling following chemical hydrolysis. Straw samples and residues were analyzed by Fourier transform infrared spectrometry (FT-IR) whereas hydrolysate analysis was based on total reducing sugar (TRS) determination following the DNS method and capillary electrophoresis (CE) analysis. The results indicated that acetic acid and formic acid are rather mild acids yielding low TRS levels compared to the reference acid. Mechanocatalytical pretreatment slightly increased TRS yields, but not significantly. Strikingly, sulfuric acid showed an efficient conversion efficiency yielding almost 45% of TRS. Furthermore, this study provided evidence for the acetylation of straw components when acetic acid was used as catalyst. Alkali hydrolysis induced the de-esterification, but revealed no significant increase of TRS yields.     

Insight into biochar properties and its cost analysis

Biochars (BCs) are widely produced and used for the remediation of environmental contaminants as bio-sorbents. In this review, statistical analysis of different BC physico–chemical properties was conducted. It was observed that woody materials are the most suitable for preparing BCs, among many other potential raw materials such as food wastes and agricultural materials. Currently BCs are produced through a variety of thermal treatment processes between 300 and 900 °C, among which slow pyrolysis is widely used due to its moderate operating conditions and optimization of BC yields. Hydrothermal carbonisation (HTC) is also an effective approach for BC production under certain conditions. As pyrolysis temperature is increased, the carbon content, ash content, surface area, and pore volume tend to be increased while the yield, hydrogen, oxygen, nitrogen content, and H/C and O/C molar ratios tend to decrease. The economic feasibility of BCs depends on a range of factors from raw material price to efficient production technologies. Thus, the overall cost equation of a pilot BC production plant together with the cost equation for BC regeneration has been proposed. The future research directions of BCs are also elaborated.