Visible-light-driven Ag/Bi3O4Cl nanocomposite photocatalyst with enhanced photocatalytic activity for degradation of tetracycline

In this study, a novel Ag/Bi3O4Cl photocatalyst has been synthesized by a facile photodeposition process. Its photocatalytic performance was evaluated from the degradation of tetracycline (TC) under visible light irradiation (λ > 420 nm). The 1.0 wt% Ag/Bi3O4Cl photocatalyst could significantly enhance the degradation of TC compared with pure Bi3O4Cl, with the degradation level reaching 94.2% in 120 minutes. The enhancement of photocatalytic activity could be attributed to the synergetic effect of the photogenerated electrons (e−) of Bi3O4Cl and the surface plasmon resonance (SPR) caused by Ag nanoparticles, which could improve the absorption capacity of visible light and facilitate the separation of photogenerated electron–hole pairs. In addition, electron spin resonance (ESR) analysis and trapping experiments demonstrated that the superoxide radicals (˙O2−), hydroxyl radicals (˙OH) and holes (h+) played crucial roles in the photocatalytic process of TC degradation. The present work provides a promising approach for the development of highly efficient photocatalysts to address current environmental pollution, energy issues and other related areas

Compliance synthesis of a class of planar compliant parallelogram mechanisms using the position space concept

Compliant mechanisms can be reconfigured with variation of compliance performance, by changing the positions of each compliant module thereof within its position space. This paper synthesizes the compliance of two types of parallelogram mechanisms by changing the positions of compliant joints within their position spaces. Through analytical modelling, detailed analysis is implemented to uncover the influence of positions on compliance characteristics. Finally, some desired designs are presented

Rational design and synthesis of covalent triazine frameworks based on novel N-heteroaromatic building blocks for efficient CO2 and H2 capture and storage

Covalent Triazine Frameworks (CTFs), a nitrogen-rich subclass of Porous Organic Polymers (POPs), show large potential in applications including gas adsorption /separation and heterogeneous catalysis due to their distinctive large surface area, low skeleton density, good thermal and chemical stability combined with their rational tunability.1 Herein, we reported on a set of nitrogen-rich CTFs prepared by trimerization of 4,4',4'',4'''-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzonitrile under ionothermal conditions. The influence of several parameters such as ZnCl2/monomer ratio and reaction temperature on the structure and porosity of the resulting frameworks was systematically examined. After a thorough characterization, their performance in CO2 and H2 adsorption as well as their selectivity of CO2 over N2 was assessed. Notably, the CTF obtained using 20 molar equiv. of ZnCl2 at a reaction temperature of 400 ºC exhibits an excellent CO2 adsorption capacity (3.48 mmol/g at 273 K and 1 bar) as well as a significant high H2 uptake (1.5 wt% at 77 K and 1 bar). These values are among the highest measured under identical conditions to date. In addition, the obtained CTFs also present a relatively high CO2/N2 selectivity (up to 36 at 298 K) making them promising adsorbents for gas sorption and separation

Accuracy modeling and analysis for a lock-or-release mechanism of the Chinese Space Station Microgravity Platform

With development of Chinese space science and technology, plenty of microgravity experiments will be conducted in the Chinese Space Station to be built, and therefore demand for high-precision electromechanical equipment increases substantially. In this paper, a comprehensive accuracy analysis of a new type of auto lock-or-release (L/R) mechanism, which is applied in the Space Station Microgravity Platform (SSMP), is implemented. Firstly, two models (vector analysis model and vector differential model) are, therefore, proposed to analyze output errors of the mechanism. Due to transmission errors from the transmission chain of the gear mechanism, influence factors on axial errors of lead screws are analyzed using design of experiment (DOE) for factor sensitivities. It shows that manufacturing tolerances of the lead screw is the dominant factor. Then, verification of the two proposed accuracy models is comparatively implemented through Monte Carlo (MC) simulation and DOE. Using the present accuracy model, location errors of the lead screw throughout the mechanism's working stroke are illustrated, where the non-synchronous error of the mechanism is particularly discussed. A linear relation between the variance of the non-synchronous error and that of the structural error is established, followed by analyzing influence factors on the non-synchronous error

Design of experiment-based tolerance synthesis for a lock-or-release mechanism of the Chinese Space Station Microgravity Platform

This paper deals with the tolerance synthesis with the application for a typical Lock-or-Release (L/R) mechanism, used for Chinese Space Station Microgravity Platform (SSMP). The L/R mechanism is utilized to lock the SSMP maintaining space position during the launching stage, and to release the SSMP automatically during on-orbit stage. Manufacturing accuracy of L/R mechanism presents direct influence on its kinematic and dynamic behaviors. Tolerance synthesis can provide a reasonable assignment of tolerance, satisfying the critical assembly criteria while lowering manufacturing complexity. In this paper, based on the number-theory method (NTM), a Halton-set based Monte Carlo (MC) simulation is introduced in the accuracy model of the L/R mechanism, aiming at improving analytical precision and efficiency for tolerance synthesis. A design of experiment (DOE) based tolerance synthesis approach is proposed. With initial tolerance determined by capacity, sensitivities of different tolerance factors are generated through the first DOE stage, and then applied to determine feasible tolerance levels. The final tolerance assignments, like points scatted in high-dimensioned space with inherent uniformity, are then produced through uniform DOE in the second stage. Result shows that the majority of feasible tolerance assignments generated have more relaxed tolerance, which can facilitate the manufacturing process

Tuning electrochemical catalytic activity of defective 2D terrace MoSe2 heterogeneous catalyst via Co doping

This study presents successful growth of defective 2D terrace MoSe2/CoMoSe lateral heterostructures (LH), bilayer and multilayer MoSe2/CoMoSe LH, and vertical heterostructures (VH) nanolayers by doping metal Co (cobalt) element into MoSe2 atomic layers to form a CoMoSe alloy at the high temperature (~900 °C). After the successful introduction of metal Co heterogeneity in the MoSe2 thin layers, more active sites can be created to enhance hydrogen evolution reaction (HER) activities combining with metal Co catalysis, through the mechanisms including (1) atomic arrangement distortion in CoMoSe alloy nanolayers, (2) atomic level coarsening in LH interfaces and terrace edge layer architecture in VH, (3) formation of defective 2D terrace MoSe2 nanolayers heterogeneous catalyst via metal Co doping. The HER investigations indicated that the obtained products with LH and VH exhibited an improved HER activity in comparison with those from the pristine 2D MoSe2 electrocatalyst and LH type MoSe2/CoMoSe. The present work shows a facile yet reliable route to introduce metal ions into ultrathin 2D transition metal dichalcogenides (TMDCS) and produce defective 2D alloy atomic layers for exposing active sites, and thus eventually improve their electrocatalytic performance

Experimental study on the repair of peripheral nerve injuries via simultaneously coapting the proximal and distal ends of peripheral nerves to the side of nearby intact nerves

IntroductionPeripheral nerve defect is a difficult disease to treat in clinical practice. End-to-side anastomosis is a useful method to treat it. At present, the end-to-side anastomosis method does not involve the proximal nerve, which results in a waste of proximal donor nerves, and even the formation of traumatic neuromas at the proximal end. The patients suffer from traumatic neuralgia and the curative effect is unsatisfactory.MethodsIn this study, an improved end-to-side anastomosis technique was proposed in this study: both the proximal and distal ends of the damaged common peroneal nerve were sutured to an adjacent normal tibial nerve. Moreover, the possible role and mechanism of the proposed technique were explained at the physiological and anatomical levels. In this study, a 10 mm common peroneal nerve defect was made in SD rats, and the rats were randomly divided into three groups. In Group I, the distal end of the common peroneal nerve was attached end-to-side to the fenestrated tibial nerve adventitia, and the proximal end was ligated and fixed in the nearby muscle. In Group II, the tibial nerve adventitia was fenestrated and the epineurial end-to-end anastomosis surgery was performed to suture the proximal and distal ends of the common peroneal nerve. Rats in Group III were taken as control and received sham operation. Twelve weeks after the operation, the recovery of the repaired nerve and distal effector functions were examined by the sciatic functional index, electrophysiology, osmic acid staining, the muscle wet weight ratio, and the muscle fiber cross-sectional area.ResultsIt was found that these results in Group II were similar to those in Group III, but better than those in Group I. Through retrograde tracing of neurons and Electrophysiological examination in Group II, the study also found that the proximal common peroneal nerve also could establish a connection with tibialis anterior, even gastrocnemius.DiscussionTherefore, it is inferred that fostering both the proximal and distal ends of defective peripheral nerves on normal peripheral nerves using the end-to-side anastomosis technique is a more effective approach to repairing injured nerves