A NOVEL DESIGN OF 17.5 KV HV FEEDTHROUGH FOR ARJUNA 2.0

A NOVEL DESIGN OF 17.5 KV HV FEEDTHROUGH FOR ARJUNA 2.0. A novel design of the 17.5 kV feedthrough for Arjuna 2.0 Cockcroft Walton generator has been proposed. It is used for connecting the output of RF transformer oscillator (in the outside of horizontal vessel) with the input of voltage multiplier (inside of horizontal vessel) of the Cockcroft Walton generator. It was equipped by covers on left and right side. The designed feedthrough was simple, compact, easy to manufacture, high performance to prevent flashover and also it was applied to Arjuna 2.0 Cockcroft Walton. It was made from teflon (PTFE) and solid copper, which have high dielectric strength, capable of withstanding press loads, and easy to manufacture. The shortest distance between grounding with conductor radially was 43.25 mm, and 253.5 mm for feedthrough surface. The design was verified by Finite Element Method software and continued with performance testing. According to simulation, the stress of voltage is high about 16 kV to 17.5 kV on feedthrough conductor and 0 to 3 kV on feedthrough flange. The electric field of the covered feedthrough is lower than the coverless feedthrough. The highest and lowest electric fields are 1.26 x 106 V/m and 1 x 105 to 2 x 105 V/m respectively. Furthermore, feedthrough has been tested up to 120 kV and no discharge occurred. It means this design can be operated for 17.5 kV and it was successful installed on Arjuna 2.0 Cockcroft Walton generator.

Wetting of solid copper with liquid indium in a superhigh vacuum and a gas medium and calculation of their interphase energies depending on the temperature

In the article, using the experimental data obtained in recent years on the contact angles and surface energies of solid copper and liquid indium, their interfacial energies are calculated at different temperatures. Knowledge of the interfacial characteristics is dictated by the need to obtain new materials that can operate under extreme conditions. For these and some other purposes in modern engineering and technology, they began, for example, to use high-vacuum brazing of high-temperature metal products using low-temperature metals and alloys. An important role in such processes is played by the interfacial energy at the solid-melt interface, which determines the contact angle: the lower the interfacial energy, the smaller the contact angle, and the smaller the contact angle, the better the processes of soldering, welding and liquid-phase sintering, etc. etc. Unfortunately, until now there is no direct method for measuring the interfacial energy. Therefore, the calculation of this value is an urgent task.

Mutant Strains of Escherichia coli and Methicillin-Resistant Staphylococcus aureus Obtained by Laboratory Selection To Survive on Metallic Copper Surfaces

ABSTRACT Artificial laboratory evolution was used to produce mutant strains of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) able to survive on antimicrobial metallic copper surfaces. These mutants were 12- and 60-fold less susceptible to the copper-mediated contact killing process than their respective parent strains. Growth levels of the mutant and its parent in complex growth medium were similar. Tolerance to copper ions of the mutants was unchanged. The mutant phenotype remained stable over about 250 generations under nonstress conditions. The mutants and their respective parental strains accumulated copper released from the metallic surfaces to similar extents. Nevertheless, only the parental strains succumbed to copper stress when challenged on metallic copper surfaces, suffering complete destruction of the cell structure. Whole-genome sequencing and global transcriptome analysis were used to decipher the genetic alterations in the mutant strains; however, these results did not explain the copper-tolerance phenotypes on the systemic level. Instead, the mutants shared features with those of stressed bacterial subpopulations entering the early or “shallow” persister state. In contrast to the canonical persister state, however, the ability to survive on solid copper surfaces was adopted by the majority of the mutant strain population. This indicated that application of solid copper surfaces in hospitals and elsewhere has to be accompanied by strict cleaning regimens to keep the copper surfaces active and prevent evolution of tolerant mutant strains. IMPORTANCE Microbes are rapidly killed on solid copper surfaces by contact killing. Copper surfaces thus have an important role to play in preventing the spread of nosocomial infections. Bacteria adapt to challenging natural and clinical environments through evolutionary processes, for instance, by acquisition of beneficial spontaneous mutations. We wish to address the question of whether mutants can be selected that have evolved to survive contact killing on solid copper surfaces. We isolated such mutants from Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) by artificial laboratory evolution. The ability to survive on solid copper surfaces was a stable phenotype of the mutant population and not restricted to a small subpopulation. As a consequence, standard operation procedures with strict hygienic measures are extremely important to prevent the emergence and spread of copper-surface-tolerant persister-like bacterial strains if copper surfaces are to be sustainably used to limit the spread of pathogenic bacteria, e.g., to curb nosocomial infections.

Synthesis and Analysis of Copper Neem (Azadirechta Indica) Soap-Nitro and Ethoxy Benzothiazole Complexes for Anti-Bacterial Activity Related with Skin Diseases

The solid copper(II) soap derived from Neem (Azadirechta Indica)oil and its complex with ligand containing nitrogen, sulphur and oxygen atoms like 2-amino -6-nitro benzothiazole and 2-amino- 6-ethoxy benzothiazole have been synthesized and characterised by elemental analysis, IR spectroscopy and biological studies. From the analytical data, the stoichiometry of the complex has been observed to be 1:1 (metal:ligand). The derived compounds were found active against Staphylococcus aureus,Coagulase-negative staphylococci (CoNs), Acinetobacter baumanii, Pseudomonas aeruginosa and micrococcus bacteria. These findings have high medical, industrial and economic significance as copper (II) soap and copper (II) soap complex could be harnessed in the formulation of medicated soaps.

THE EFFECT OF FINS PERFORATION AND MATERIAL TYPE ON THERMAL PERFORMANCE OF A HEAT SINK UNDER NATURAL CONVECTION

An experimental study was done to investigate the effect of fin geometrymodification and material type on heat dissipation from a heat sink under natural convection.v-corrugated solid fin and v-corrugated perforated fin were designed for this purpose.Aluminum and Copper metals were selected in designing the fins because their wideapplication in cooling and heating equipment. Three different voltages 110, 150 and 200 Vsupplied to the heat sink to study their effects on the fins performance. Each experimentrepeats two times to reduce the error and the data recorded after reaching the steady stateconditions. The utilization of solid and perforated v-corrugated fins is compared. The resultsshowed that perforated fins dissipated heat more than corresponding solid by 15.4, 34 and32% for aluminum, and 2.7, 2.1 and 4.3% for copper fin in the three voltages. Also, theresults indicated that the heat loss by solid copper fin is greater by 56, 72 and 92% thancorresponding solid aluminum fin and for perforated fin case by 38, 31.7 and 51.9 % at110,150 and 200 V respectively.