Regulating surface state of ZnIn2S4 by gamma-ray irradiation for enhanced photocatalytic hydrogen evolution

Surface vacancy has been demonstrated to be an active site in photocatalytic hydrogen evolution reaction (HER) over sulfide and oxide. In this work, surface S vacancy was regulated by high-energy...

Studies on Surface Plasmon Resonance of Murdannia loriformis Silver Nanoparticles

In this work, surface plasmon resonance (SPR) was investigated over the effect of concentration of metal precursor, concentration of reducing agent, reaction time and pH on formation of silver nanoparticles (AgNPs) using biological method. In this method, Murdannia loriformis extract (MLE) was used as reducing agent and silver nitrate as metal precursor. SPR of Murdania loriformis silver nanoparticles (MLE-AgNPs) was measured through UV-vis spectrophotometer over a range of 380 – 800 nm wavelength. It was found that, as the concentration of MLE, pH and reaction time increases, the SPR peak of MLE-AgNPs at 430 - 490 nm also increases. However, for effect of concentration of metal precursor, the result showed that SPR peak of MLE-AgNPs increases when 1 to 5 mM of silver nitrate was used but decreases for 10 and 15 mM. Significant of this study is to identify the optimum conditions for synthesis of MLE-AgNPs.

Justification of the geometric dimensions of drum sorting machine

This article presents the results of research to determine the basic geometric dimensions of a drum sorting machine designed for potato sorting. A critical analysis of the current situation in this area has been carried out. A number of research works have been studied aimed at developing special methods to reduce manual labour and improve the quality of sizing and sorting potatoes. At the same time, it is important to sort by size with a low level of product damage, with high productivity. Known mechanical and robotic machines used for sorting potatoes: roller, drum, conveyor (belt) and combined. And also, with the help of machine and computer vision, laser backscattering of light, ultrasonic, visual and spectral analysis systems, optical, acoustic intelligent sorting systems. Among the mechanical ones, the drum sorting machine is the simplest in design. The disadvantage of this machine is that during operation the product to be sorted is only in the lower part of the drum, i.e. only part of the work surface is used. To eliminate the abovementioned disadvantage, a new design of the machine is recommended. Where the sorting surface is made of elastic mesh, the size of the holes increased in the direction of movement of the ends along the sorting surface. The ends are connected and pulled together on two drums. The holes of the elastic mesh material vary in size, the size of the holes increases from the beginning to the end of the sorting surface. The drum can be in a truncated cone or a cylinder shape. To ensure the efficient operation of the proposed machine, mathematical calculations are derived, including geometric and kinematic parameters.

UV-C LED Irradiation Reduces Salmonella on Chicken and Food Contact Surfaces

Ultraviolet (UV-C) light-emitting diode (LED) light at a wavelength of 250–280 nm was used to disinfect skinless chicken breast (CB), stainless steel (SS) and high-density polyethylene (HD) inoculated with Salmonella enterica. Irradiances of 2 mW/cm2 (50%) or 4 mW/cm2 (100%) were used to treat samples at different exposure times. Chicken samples had the lowest Salmonella reduction with 1.02 and 1.78 Log CFU/cm2 (p ≤ 0.05) after 60 and 900 s, respectively at 50% irradiance. Higher reductions on CB were obtained with 100% illumination after 900 s (>3.0 Log CFU/cm2). Salmonella on SS was reduced by 1.97 and 3.48 Log CFU/cm2 after 60 s of treatment with 50% and 100% irradiance, respectively. HD showed a lower decrease of Salmonella, but still statistically significant (p ≤ 0.05), with 1.25 and 1.77 Log CFU/cm2 destruction for 50 and 100% irradiance after 60 s, respectively. Longer exposure times of HD to UV-C yielded up to 99.999% (5.0 Log CFU/cm2) reduction of Salmonella with both irradiance levels. While UV-C LED treatment was found effective to control Salmonella on chicken and food contact surfaces, we propose three mechanisms contributing to reduced efficacy of disinfection: bacterial aggregation, harboring in food and work surface pores and light absorption by fluids associated with CB.

Features of arc discharges and erosion phenomena

Low-voltage electrical appliances play an important role in ensuring the control of energy processes, protection and switching of electrical circuits. Problems that occur in low-voltage electrical devices at rated currents of 32 - 1000 A, relate to electrical contacts that determine the operation of electrical devices. The main contribution to the development of erosion of the working surface is made by an electric arc, which is formed in the inter-contact gap when opening electrical contacts. In world practice, existing solutions to increase the arc resistance of electrical contacts do not completely solve the problem of reducing erosion of their work surface. The use of additional devices in arc suppression systems leads to an increase in the size of electrical devices. The use of expensive and toxic elements in the compositions leads to an increase in the cost of electrical appliances and poisoning of the environment. Strengthening the composition of the contacts through the use of refractory elements leads to an increase in the transient resistance. The aim of the study was to substantiate and develop the main provisions of the theory of processes and phenomena that occur on the work surface and in the electrode areas of electrical contacts, and to create compositions of high arc contact compositions for switching electrical devices. The theory of the mechanism of movement of arc reference points on the working surface of electrical contacts is substantiated and the factors providing increased arc resistance due to thermoemission properties of contact composition compositions that control diffusion, migration and phase transformations during chemical reactions are obtained. It has been experimentally established and theoretically confirmed that electric erosion is mainly determined by the microstructure of the material and the change in the physical and mechanical properties of the ingredients on the working surface of the contact parts during current switching. Key words: anode, cathode, erosion, contact wear, working surface, arc column, arc resistance, transient resistance

ABRASIVE JET MACHINING AND OPTIMIZATION OF PROCESS PARAMETERS

Abrasive Jet Machining also known as micro-abrasive blasting or pencil blasting is one of the mechanical energy based economical non-traditional machining process for cutting, deburring, polishing, drilling, etching and cleaning of alloys, brittle metals and non-metallic materials due to its high degree of flexibility and low stress forces with less heat generation.In AJM process, fine abrasive grits (silicon carbides, Aluminium oxides, Sodium bicarbonate, Boron Carbides, Crushed glass and Dolomite etc.) of typically ~0.025 mm are accelerated in a high velocity (150-300 m/s) jet of gas stream or air which is generated by converting pressure energy of carrier gas or air to its Kinetic energy and hence high velocity jet and nozzle directs abrasive jet in a controlled manner towards the work surface. Small fractures are created after impacting abrasive particles on the work surface.

Standardized aseptic dressing change procedure: Optimizations and adherence in a prospective pre- and postintervention cohort study

Background: The “HygArzt” project investigated the effectiveness of hygiene measures introduced by an infection prevention link physician (PLP). Objective: To investigate whether the introduction of a standardized aseptic dressing change concept (ADCC) by a PLP can increase hand hygiene adherence and adherence to specific process steps during an aseptic dressing change (ADC) in a trauma surgery and orthopedic department. Methods: We defined 4 required hand disinfection indications: (1) before the preparation of ADC equipment, (2) immediately before the ADC, (3) before the clean phase, and (4) after the ADC. A process analysis of the preintervention phase (331 ADCs) was used to develop a standardized ADCC. The ADCC was introduced and iteratively adopted during the intervention phase. The effect was evaluated during the postintervention phase (374 ADCs). Results: Hand hygiene adherence was significantly increased by the introduction of the ADCC for all indications: (1) before the preparation of the ADC equipment (from 34% before to 85% after, P <.001), (2) immediately before an ADC (from 32% before to 85% after; P < .001), (3) before the clean phase (from 42% before to 96% after; P < .001), and (4) after an ADC (from 74% before to 99% after; P < .001). Overall hand hygiene adherence was analyzed before the indications for an ADC (from 9.6% before to 74% after; P < .001). The same strategy was applied to the following process parameters: use of a clean work surface, clean withdrawal of equipment from the dressing trolley, and appropriate waste disposal. Conclusions: A PLP sufficiently implemented a standardized concept for aseptic dressing change during an iterative improvement process, which resulted in a significant improvement in hand hygiene and adherence to other specific ADCC process steps.

TAGUCHI GREY RELATIONAL MULTI-RESPONSE EXPERIMENTAL OPTIMIZATION ON MODIFICATION OF Al-6061 SURFACE USING Si–Cu GREEN COMPACT TOOL IN EDM

This paper presents the surface modification of aluminium-6061 by electric discharge machining (EDM). Si–Cu powder metallurgical green compact tool is used to deposit its material on to the work surface under reverse polarity of EDM. Compact load, current and pulse on-time are selected control parameters. Material deposition rate (MDR), tool wear rate (TWR) and surface roughness ([Formula: see text] are considered as process outputs. Scanning electron microscopic (SEM) analysis and energy dispersive X-ray (EDX) analysis show the presence of tool materials in the deposit of work surface. Olympus optical micrograph shows an average thickness of the deposited layer to be 18.73[Formula: see text][Formula: see text]m. The hardness of the deposited layer is found to be 268[Formula: see text]HV. Analysis of variance (ANOVA) shows the compact load to be the most effective parameter on surface modification followed by pulse on-time and current, respectively.

CHOICE OF ALLOY, COATING AND GEOMETRICAL PARAMETERS OF CUTTER PLATE FOR FACE MILLING OF HIGH-CARBON HARDENED 95H18-Sh STEEL

The application of hardened steel parts for the purpose of wear-resistance increase becomes increasing spread in different branches of mechanical engineering. In view of high hardness of the work surface of parts, finishing is carried out by flat grinding. During the hardened steel grinding there are formed burns, cracks, admixtures of abrasive particles in the work surface which are inadmissible defects in a surface layer of critical parts mounted in the fuel unit of an aviation engine. The analysis of literature and company experience has shown that after thermal treatment instead of finishing is necessary to use surface finishing by a face milling method, but there are no sufficient recommendations for tool choice and cutting modes to date. Jointly with the educational department there are carried out theoretical researches of cutters for the face milling of the “selector housing” mass-produced parts consisting of corrosion-resistant 95H18-Sh steel with the hardness of 59÷61 HRC. In the paper there is considered a chemical composition of 95H18-Sh steel, a method for manufacturing a cast, its physical, mechanical and chemical properties. Taking into account data obtained for the face-milling cutter installation on the frame there was chosen Sandvik Coromant material for the replaceable cutting insert the base of which consists of hard alloy 1010 with PVD coating. Later on there was carried out selection of basic geometrical parameters and characteristics of a cutting plate and also a micro-geometry of a major cutting edge and a tip. Mass-produced replaceable through-away plates with R245-12 T3 M-PM number of 1010 hard alloy and PVD coating were obtained from the catalog of Sandvik Coromant company. At the end of the work a conclusion was drawn that the application of face milling will allow ensuring the requirements to the design documentation of the product, decreasing thermal and power stress of the process, increasing productivity, surface quality and excluding the necessity in abrasion, and the investigation results are applicable to the fulfillment of the complete factor experiment and computation of a simulator with the definition of the impact of variable factors upon a response function.