Search

Nanofiltration (NF) membranes as high selective separators are appealing for molecular sieving, which still remains a great challenge for the mixed dyes with same charge. In this study, cellulose acetate (CA) membranes were firstly aminated by ethylene imine polymer (PEI), and then the thin film of metal organic frameworks (MOFs) were constructed onto aminated CA membrane through forward-diffusion, slow crystallization and in situ growth of FeCo-Prussian blue (FeCo-PB) crystallization layers. The designed PB@CA composite NF membrane shows an ideal rejection for Congo red (CR)/methyl orange (MO) mixture solution, with 99.7%±0.2% for CR and 33.5%±2% for MO. In addition, the composite NF membrane demonstrated good efficiency for photocatalytic degradation of organic fouling (permeability recovery ratio was up to 92%) due to the active FeCo-PB micro-cubes. Thus, this work provides a practical strategy to prepare MOFs mediated thin film composite nanofiltration membrane for precise molecular sieving and catalytic antifouling performances. [ABSTRACT FROM AUTHOR]

The variations in the Earth's rotation are important to space dynamic theory and natural disasters because they affect the length-of-day (LOD) and consequently human lives. We use maximum entropy method (MEM), Lomb method (LOMB), and phase dispersion minimization (PDM) to determine the natural periods of equally spaced LOD time series. We transform the observational monthly LOD time series (LODM) to unequally sampled series (LODMD) by removing every fourth, third, and half of the total samples. We also apply spline interpolation to LODMD to yield equally spaced time series (LODMDN). The results suggest that regardless of the time series, the MEM frequency is 0.1660 month−1 and 0.0840 month−1, whereas LOMB and PDM yield 0.166 month−1 and 0.083 month−1, respectively. Furthermore, missing data that are less than half of the total data or spline interpolation do not affect the analysis. For the amplitude, neither missing data nor spline interpolation affect the analysis. [ABSTRACT FROM AUTHOR]

Spindles are among the key parts of rotatory machinery and featured widely in a variety of industrial equipment. Fracture failure of a spindle (caused either by inappropriate design or operation) could lead to significant economic losses or high numbers of casualties. Using data from accidents, caused by spindle fracture in centrifuges in China as an example, this research work systematically investigates the reasons leading to the fracture failure of the spindles in operation. Our methods include analysing the chemical composition, micro-morphology, and mechanical properties of the fractures. Our results show that the spindle failure is due to a form of fatigue fracturing caused by stress concentration and alternative bending stress. A finite element method was additionally utilised to further calculate and analyse the stress distribution over a spindle. It was discovered that the stress is severely concentrated at the transition fillet of the spindle. Finally, we show that the stress distribution in the spindle can be improved by adopting a structure in the form of a conic section and by reducing the eccentric moment. In this way, the fatigue resistance of a spindle can be enhanced. [ABSTRACT FROM AUTHOR]

Due to various errors such as the radial distortion of lenses and perspective distortion in digital images, there are non-linear geometric distortions in such images. Therefore, a new method based on the black-white square array is proposed to calibrate visual measuring systems at a micro-sized measurement scale. Meanwhile, by analysing the sources of error, the binary cubic polynomial model for a curved error surface is established. Thereafter, the sub-pixel coordinates of each edge of the checkerboard calibration board are extracted to obtain the coordinates of corner points, which are regarded as the actual point coordinates. Later, the actual point coordinates are combined with the theoretical point coordinates to establish equations, so as to find the coefficients of the error model through fitting. On this basis, calibration is performed on the backlight visual measuring system at a micro-sized measurement scale. As verified experimentally, the proposed method is endowed with high measurement accuracy and robustness. Meanwhile, characterised by its simple and reliable calibration process, it has been applied in a system used for detecting the aperture and centre distance of the intermediate features in gear pumps. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT)-based nanocomposites embedded with ZnO nanowhiskers (ZnOw) were fabricated by solid state processing. There were no unwanted reaction phases between the PZT and ZnOw. Compared with monolithic PZT, the mechanical properties increased significantly and the piezoelectric properties decreased slightly. Several probable mechanisms of whiskers responsible for reinforcement of the PZT/ZnOw nanocomposites are proposed. [Copyright &y& Elsevier]

In the face of global climate change and the need for energy diversification, electrocatalytic technology emerges as an eco‐friendly solution. However, persistent electrode failures hinder long‐term stability. This review comprehensively outlines the primary causes leading to the failure of self‐supported electrodes, encompassing substrate passivation, substrate/catalyst dissolution, CO poisoning, catalyst migration and agglomeration, as well as cathodic etching. Proposed strategies center on material design, emphasizing anchoring, lattice matching, substrate stability, and morphological control. Advanced characterization techniques and in situ technologies offer promising ways. The integrated deployment of these strategies will provide crucial guidance and support for the sustainable advancement of electrocatalytic technology. [ABSTRACT FROM AUTHOR]

The electrocatalytic selective oxidation of 5‐hydroxymethylfurfural (HMF) presents a highly efficient and eco‐friendly method for biomass utilization. Herein, we synthesized pure β‐Ni(OH)2 and amorphous Ni(OH)2 on nickel foam (NF) using a facile stepwise electrodeposition technique and evaluated their catalytic performances for the oxidation of HMF to 2,5‐furan dicarboxylic acid (FDCA). The β‐Ni(OH)2 nanosheets‐decorated electrode (β‐NiNS/NF) exhibited excellent interfacial lattice matching with the substrate nickel, resulting in enhanced electron transfer at the catalyst‐substrate interface, as confirmed by electrochemical analysis. Consequently, the β‐NiNS/NF electrode displayed improved intrinsic electrocatalytic activity and interfacial stability. Additionally, it demonstrated effective HMF adsorption capability. These advantageous properties led to enhanced HMF conversion, selectivity, and structural stability. Notably, the β‐NiNS/NF electrode achieved an unprecedented FDCA yield of 80.6 % under relatively large current density galvanostatic electrolysis commonly used in industry. Moreover, our investigation identified a novel possible oxidation pathway during HMF electrocatalysis. This study not only showcases an efficient and scalable synthetic approach but also highlights the potential of the β‐NiNS/NF electrode for industrial HMF electrocatalytic oxidation under conditions involving relatively large applied currents. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effectiveness of Governor vessel acupuncture (GV Ac) in treating post-stroke cognitive impairment (PSCI). There was a total of seven databases examined. Four English databases (Cochrane Library, PubMed, Embase, and Medline) and three Chinese databases (Chinese National Knowledge Infrastructure (CNKI), Chinese Science and Technology Periodical Databases (VIP), and Wan Fang Database) contain all randomized controlled trials (RCTs) comparing Governor vessel acupuncture to other treatments or none acupuncture for PSCI. The exact dates for the search period are from January 1, 2000, to January 1, 2023.Two researchers independently reviewed the literature, gathered RCT data, and performed statistical analysis. All data were analyzed using Review Manager software (Rev Man) 5.3. This meta-analysis includes a total of 39 trials with 2044 patients. There were 1022 participants in each of the test and control groups. Following 12–120 days of acupuncture treatment, a meta-analysis revealed that the treatment groups (GV Ac combined with conventional treatment groups) significantly increased their scores on the Curative ratio (OR = 3.00, 95 %CI = 2.37–3.79, P = 0.98, I² = 0 %), Montreal Cognitive Assessment (MoCA)(MD = 1.82, 95 %CI = 1.60–2.03, P = 0.11, I² = 25 %), Mini-Mental State Examination (MMSE)(MD = 2.18, 95 %CI = 1.64–2.72, P<0.005, I² = 92 %), and Activity of Daily Living (ADL)(MD = 5.99, 95 %CI = 5.33–6.64, P = 0.19, I² = 26 %). The results suggested that acupuncture on points of the Governor vessel enhanced cognitive function in stroke survivors. • The pooled data revealed that acupuncture on points of the Governor vessel enhanced cognitive function in stroke survivors. [ABSTRACT FROM AUTHOR]

Abstract: Zinc oxide whiskers (ZnOw) reinforced lead zirconate titanate (PZT) piezoelectric composites with high strength and high toughness were fabricated by nonpressure sintering at 1100°C. Addition of ZnOw is effective for sinterability and densification of the composites. Incorporating ZnOw to PZT ceramics contributes to an obvious improvement of the fracture properties. The fracture strength and fracture toughness of the composites incorporating 2wt.% ZnOw, compared with the monolithic PZT, are enhanced 46% and 47%, respectively. Improvement of fracture strength is ascribed to the enhancement of the elastic modulus and fracture toughness. Enhancement of fracture toughness is associated with the existence of the observed several mechanisms including crack deflection, whisker bridging, whisker pull-out and rupture due to the intergranular and intragranular whiskers. [Copyright &y& Elsevier]

Renewable energy storage is a key issue in our modern electricity-powered society. Lead acid batteries (LABs) are operated at partial state of charge in renewable energy storage system, which causes the sulfation and capacity fading of Pb electrode. Lead-carbon composite electrode is a good solution to the sulfation problem of LAB. In this paper, a rice-husk-derived hierarchically porous carbon with micrometer-sized large pores (denoted as RHC) has been used as the component of lead-carbon composite electrode. Scanning electron microscopy was used to characterize the morphology of lead-carbon composite electrode. Electrochemical impedance spectroscopy was used to determine the charge transfer capability of lead-carbon composite electrode. Both full charge-discharge method and charge-discharge method operating at harsh partial state of charge condition have been used to prove the superior energy storage capability of lead-carbon composite electrode. Experiment results prove that the micrometer-sized pores of RHC are beneficial to the construction and stability of lead-carbon composite electrode. Microporous carbon material with high surface area is not suitable for the construction of lead-carbon electrode due to the ruin of lead-carbon structure caused by severe electrochemical hydrogen evolution. [ABSTRACT FROM AUTHOR]

A supercritical carbon dioxide (ScCO) assisted phase inversion was developed to produce microporous poly(vinylidene fluoride) (PVDF) membranes whose morphology characteristics arise from both liquid-liquid demixing and solid-liquid demixing (crystallization). This result was confirmed by Fourier transform infrared spectroscopy (FTIR), from which both α and β crystals were found. As revealed by contact angle experiment, the PVDF membranes prepared via ScCO assisted phase inversion were more hydrophobic compared with the control membrane produced via conventional immersion-precipitation technique. In particular, the sample with 15 wt% PVDF prepared at 45 °C and 13 MPa exhibited a contact angle of 142°, which was mainly caused by the multilevel micro- and nano-structure. The effects of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP) and lithium chloride (LiCl) on the structures and crystal form were investigated. PVP promoted the formation of α phase crystal form, while PEG boosts the evolution of β phase. LiCl restrained the crystallization degree of PVDF membrane under ScCO. [ABSTRACT FROM AUTHOR]

The effect of electrode configuration on mass transfer rate in a tubular electrochemical reactor was investigated with the limiting-current method. The expression of mass transfer enhancement factor was derived from the dimensionless equations for different electrode configurations. Furthermore, the local velocity distribution in the tubular electrochemical reactor was simulated by computational fluid dynamics technology. These simulation results explained the reason of mass transfer enhancement for mesh electrode: the rotation of the solution is induced by high rates of shear, and small eddies are formed. The local velocity distributions in bulk for X-dimension get flatter because of the lateral momentum transfer. Due to the impact and obstruction of electrode holes, the turbulence of the electrolyte gets drastic and the mass transfer performance in the tubular electrochemical reactor is improved. [ABSTRACT FROM AUTHOR]

Abstract: Lead zirconate titanate (PZT) based piezoelectric composites embedded with ZnO nanowhiskers (ZnOw) were investigated to clarify the optimal sintering condition for densification, microstructure, and electrical properties. The samples are characterized by X-ray diffraction analysis and scanning electron microscopy. The results show that the increase of the sintering temperature and time is quite effective in improving the densification and piezoelectric properties of the PZT/ZnOw composites. However, the relative density and piezoelectric properties deteriorate as the composites are sintered over the optimal sintering condition. Particularly, the PZT/ZnOw composites sintered at 1150°C for 2h show excellent electrical properties of piezoelectric constant d 33 ∼471pC/N, relative dielectric constant ɛ ∼3838, planar electromechanical coupling factor k p ∼0.543, remnant polarization P r ∼23.2μC/cm2 and coercive field E c ∼9.2kV/cm. [Copyright &y& Elsevier]

Abstract: ZnO whiskers and Sb2O3 co-modified lead zirconate titanate (denoted as PZT/ZnO w /Sb2O3) piezoelectric composites were fabricated using a solid state sintering technique. The characteristic diffraction peaks of the PZT perovskite and ZnO phases were identified from all the composites, suggesting the retention of these individual phases. The grain size of PZT was found to be reduced with Sb2O3 addition. A high relative density of 96.5%–99.1% was achieved in PZT co-doped with ZnO w and Sb2O3. Both the piezoelectric and mechanical properties of the PZT/ZnO w /Sb2O3 composites showed significant improvement over the monolithic PZT. The intrinsic effects of ZnO w and Sb2O3 on the electrical and mechanical properties of the PZT/ZnO w /Sb2O3 composites were discussed. [Copyright &y& Elsevier]