An Innovative Air Purification Method and Neural Network Algorithm Applied to Urban Streets

In the present work, multiphysics modeling was used to investigate the feasibility of a photocatalysis-based outdoor air purifying solution that could be used in high polluted streets, especially street canyons. The article focuses on the use of a semi-active photocatalysis in the surfaces of the street as a solution to remove anthropogenic pollutants from the air. The solution is based on lamellae arranged horizontally on the wall of the street, coated with a photocatalyst (TiO2), lightened with UV light, with a dimension of 8 cm × 48 cm × 1 m. Fans were used in the system to create airflow. A high purification percentage was obtained. An artificial neural network (ANN) was used to predict the optimal purification method based on previous simulations, to design purification strategies considering the energy cost. The ANN was used to forecast the amount of purified with a feed-forward neural network and a backpropagation algorithm to train the model.

Simulation of lubricating oil centrifugal separator performance index influence on marine diesel engine wear

Представлена методика подбора центробежного сепаратора для комбинированных систем тонкой очистки моторного масла в двигателях внутреннего сгорания. Предложен показатель (индекс производительности сепаратора), который характеризует интенсивность разделения гетерогенных систем центрифугированием. Показана зависимость скорости изнашивания основных деталей дизеля от качества используемых горюче-смазочных материалов и интенсивности очистки масла (индекса производительности сепаратора). Рассмотрены преимущества комбинированной системы очистки смазочного масла, включающие в себя центробежный сепаратор, обеспечивающий очистку масла от нерастворимых загрязнений мелкодисперсной фазы работающий совместно с саморегенерирующимся фильтром. Благодаря такому сочетанию обеспечивается минимальной изнашивание пар трения дизеля. Преимущество данного метода очистки также заключается в возможности обеспечения автономной работы механизмов смазочной системы при сохранении высокой эффективности очистки. С помощью экспериментального моделирования определено минимальное значение индекса производительности центробежного сепаратора, необходимое для стабилизации изнашивания деталей дизеля и достижения ресурсосберегающего маслоиспользования. Проиллюстрировано сравнение результатов моделирования с экспериментальными данными. Methods of centrifugal separator selection for lubricating oil combined purification systems of internal combustion engines are represented. Purification intensity parameter (performance index) for description of heterogeneous medium separation is offered. The relation between separation intensity (separator performance index) and engine wear is shown as well as its dependence on fuel and lubricating oil quality. Advantages of lubricating oil combined cleaning method by means of centrifugal purifier, used for insoluble particles removal together with the self-regenerating filter are represented. Due to their combination the minimum wear of diesel engine friction coupling can be achieved. Benefits of the method lie in autonomous operation of lubricating system for a long period of time together with high purification efficiency. Minimum value of separator performance index, required to stabilize engine parts wear and achieve resource-saving oil use has been determined by means of experimental design. Simulation results have been compared with experimental data and effect of comparison has been represented.

EFFECT OF Sr ADDITION ON THE MICROSTRUCTURE AND PROPERTIES OF THE A356 Al ALLOY

An effective way of integrating purification and modification is used for casting the A356 Al alloy. Self-generated inclusion-eliminating flux exhibits excellent purification in the alloy with an inclusion-removal rate of 74 %. The grains of eutectic silicon are fine or vermicular, and diffusely distributed in the A356 Al alloy at a 0.012 w/% Sr addition. The mechanical properties of the alloy are significantly improved, including a tensile strength of 208.5 MPa and an elongation of 17.5 %. As the Sr addition is increased, the comprehensive properties of the material are not improved. The Sr addition can be reduced to a certain degree during the modification of the melt after high purification. The addition of 0.012 w/% Sr is most preferable in the alloy.

Eco-green machining of superalloy A286: Assessment of tool wear morphology and surface topology

Unstable crude oil derivatives are among the main substances added to the mineral-based lubricants (MBL). However, the high purification and disposal costs of such lubricants and consequent environmental difficulties are the major drawbacks of cutting fluid consumption. The lower use of MBL or replacing them with less harmful ones, in principle, vegetable-based lubricants (VBL) are the prime importance of achieving less operating costs and pollution. Furthermore, the use of VBLs is much more recommended if machinability aspects, including tool life, surface, and edge quality, would also be improved. Therefore, in the present study, cutting parameters and lubricant types were used as the experimental variables in the MQL-turning of A286 superalloy. A286 is classified as a difficult-to-cut material with a wide range of applications in the energy and turbine industries. No experimental study was found on the machining of A286 under separate cooling and lubrication with two MQL systems simultaneously. The effects of cutting parameters on both average surface roughness Ra and tool wear morphology were evaluated. Experimental results denoted that the use of VBLs led to better surface topology. On the other hand, the tendency of the built-up layer (BUL) and built-up edge (BUE) phenomenon were intensified when MBL was used. On the word, better tool life is also expected when using VBL. This observation revealed that the use of VBL not only tends to improve productivity and environmental safety aspects but also machinability aspects; in principle, better surface topology and longer tool life are also expected.

Removal of Pollution by Intensive Aeration Technology for Landfill Leachate Treatment

Background. Landfill leachate is a source of environmental pollution and a major concern for human health because it contains high concentrations of organic and inorganic contaminants. Objectives. The objective of the present study is to validate the efficiency of the forced aeration treatment technique, which consists of intensively injecting a continuous oxygen flow of 16.75 kg/m3/h for 30 days using a bubble air diffuser in a relatively small volume of 1 m3. The principle of the technique is essentially based on acceleration of the degradation of the effluent as well as reduction of the organic and nitrogenous matter contents. Methods. Forced aeration technology was used for the treatment of leachate from the Mohammedia-Benslimane landfill. The sample was treated by injecting a flow of oxygen to accelerate the biodegradability of the pollutants by the microorganisms. Results. The physicochemical characterization of the raw leachate at the inlet of the aeration tank showed high values for chemical oxygen demand (COD) (38,600 mg O2/l), biological oxygen demand (BOD5) (24,000 mg O2/l), and total Kjeldahl nitrogen (TKN) (5,932.45 mg/L). The proposed treatment technique allowed relatively high purification yields to be achieved, with abatement rates for the major elements COD, BOD5 and TKN of 73%, 98%, and 85%, respectively. Conclusions. The treatment of leachate by intensive aeration technology reduces considerably the pollutant load and achieves a high purification yield. Competing Interests. The authors declare no competing financial interests.

Progress and Trend on the Regulation Methods for Nanozyme Activity and Its Application

Natural enzymes, such as biocatalysts, are widely used in biosensors, medicine and health, the environmental field, and other fields. However, it is easy for natural enzymes to lose catalytic activity due to their intrinsic shortcomings including a high purification cost, insufficient stability, and difficulties of recycling, which limit their practical applications. The unexpected discovery of the Fe3O4 nanozyme in 2007 has given rise to tremendous efforts for developing natural enzyme substitutes. Nanozymes, which are nanomaterials with enzyme-mimetic catalytic activity, can serve as ideal candidates for artificial mimic enzymes. Nanozymes possess superiorities due to their low cost, high stability, and easy preparation. Although great progress has been made in the development of nanozymes, the catalytic efficiency of existing nanozymes is relatively low compared with natural enzymes. It is still a challenging task to develop nanozymes with a precise regulation of catalytic activity. This review summarizes the classification and various strategies for modulating the activity as well as research progress in the different application fields of nanozymes. Typical examples of the recent research process of nanozymes will be presented and critically discussed.

Simple and Rapid High-Yield Synthesis of Sub-100 nm Nano-SiO2·0.5H2O Particles Based on Wollastonite

Amorphous nano-SiO2·nH2O particles has drawn much attention in industrial applications because of the features of high purification, low density, large specific surface area, fine decentralization, good optical, and mechanical performances. However, the applications have been hindered by the exorbitant price and the serious agglomeration. In this work, using wollastonite as reactant, H2SO4 as solvent, and adding sodium dodecyl benzene sulfonate (SDBS) as surfactant, sub-100 nm amorphous nano-SiO2·0.5H2O particles with good dispersibility, controllable agglomeration, narrow size distribution, and high yield were prepared by a low-cost and simple chemical method. The prepared sphere-like amorphous nano-SiO2·0.5H2O particles with average diameter of 70 nm were absorbed by the SDBS on the surface. The reaction conditions were systematically studied and the optimal technologic condition of the preparation was also confirmed. The achievement had a great perspective for the industrialization of high-quality nano-SiO2·nH2O particles, which hold great promise for various applications, such as plasmonic and catalytic nanoparticles supporting, polymeric matrices strengthening, drug delivery, and adsorption processes.

Designer bioemulsifiers based on combinations of different polysaccharides with the novel emulsifying esterase AXE from Bacillus subtilis CICC 20034

Background Bioemulsifiers are surface-active compounds, which exhibit advantages including low toxicity, higher biodegradability and biocompatibility over synthetic chemical surfactants. Despite their potential benefits, some obstacles impede the practical applications of bioemulsifiers, including low yields and high purification costs. Here, we aimed to exploit a novel protein bioemulsifier with efficient emulsifying activity and low-production cost, as well as proposed a design-bioemulsifier system that meets different requirements of industrial emulsification in the most economical way. Results The esterase AXE was first reported for its efficient emulsifying activity and had been studied for possible application as a protein bioemulsifier. AXE showed an excellent emulsification effect with different hydrophobic substrates, especially short-chain aliphatic and benzene derivatives, as well as excellent stability under extreme conditions such as high temperature (85 °C) and acidic conditions. AXE also exhibited good stability over a range of NaCl, MgSO4, and CaCl2 concentrations from 0 to 1000 mM, and the emulsifying activity even showed a slight increase at salt concentrations over 500 mM. A design-bioemulsifier system was proposed that uses AXE in combination with a variety of polysaccharides to form efficient bioemulsifier, which enhanced the emulsifying activity and further lowered the concentration of AXE needed in the complex. Conclusions AXE showed a great application potential as a novel bioemulsifier with excellent emulsifying ability. The AXE-based-designer bioemulsifier could be obtained in the most economical way and open broad new fields for low-cost, environmentally friendly bioemulsifiers.