A fast and accurate solution to optimal design of eddy-current PMCs with standard disc type

Although permanent magnet couplings (PMCs) have been under research for many years and have found successful industrial applications, this is still a technology under development. Accurate parameter determination is of significance for performance analysis and critical decisions on PMC design. However, the determination can often lead to an unacceptable increase in computation, especially when finite elements (FE) are used. The study aims to develop an FE model that is used for the structural design of a standard-disc type PMC for optimal torque. For the quick and accurate design, an integration optimal solution of the response surface methodology (RSM) and the Taguchi’s method was proposed. To verify the simulation, a series of experimental investigations were conducted on a self-developed testing platform. Furthermore, for a minimum set of FE analyses (FEA), a quantitative indicator called contribution rate, which can reflect effect level of structure parameters on the torque, was given based on the Taguchi method. Apart from this, the orthogonal matrix was used for the reduction of the FE calculation. Based on the contribution rate, the response surface methodology was adopted for the optimal torque determination with no increase in the PM volume. According to the optimization results, a fitting formula, which considers the contribution rates of the optimization variables, was presented. The results suggest that the FE simulations agree very well with the experiments, and the fitting formula can be used in the PMC design.

The Prevalence and Pattern of Enterobacter Antibiotic Resistance in the Patients Admitted to Imam Reza Hospital in Kermanshah, Iran (2016 - 2018)

Background: Antibiotic resistance is spreading worldwide against the Gram-negative bacteria that cause nosocomial infections. Objectives: The present study aimed to determine the antibiotic resistance pattern of Enterobacter isolated from the blood, urine, wound, and sputum samples of the patients referring to Imam Reza Hospital in Kermanshah, Iran. Methods: This descriptive, cross-sectional study was conducted on 649 patients with positive Enterobacter cultures at Imam Reza Hospital during 2016 - 2018. The isolates were obtained using laboratory tests based on the CLSI protocol. In addition, the standard disc-diffusion method was used to assess antibiotic susceptibility. Data analysis was performed in SPSS version 20. Results: Most cases of positive Enterobacteriaceae were isolated from the patients admitted to the intensive care unit (35.6%) and emergency ward (21.9%), as well as the urine (51.6%) and sputum samples (20.5%), respectively. Levofloxacin, ciprofloxacin, and imipenem were the most effective antibiotics against Enterobacter with the susceptibility of 56.7%, 54.8%, and 53.3%, respectively. Conclusions: According to the results, the antibiotic resistance of Enterobacter to ampicillin and ceftriaxone was high, and these antibiotics must be used correctly and reasonably. Furthermore, more epidemiological studies are required in Iran to provide national programs for preventing the spread of antibiotic resistance.

Antibiotic Resistance of Pseudomonas aeruginosa Strains in the Patients Admitted to Imam Reza Hospital in Kermanshah, Iran (2016-2018)

Background: Nosocomial infections are important medical concerns in developed and developing countries. Pseudomonas aeruginosa is considered the third leading cause of nosocomial infections following Staphylococcus aureus and Escherichia coli. Objectives: The present study aimed to determine the antibiotic resistance of isolated P. aeruginosa strains in the patients admitted to Imam Reza Hospital in Kermanshah, Iran. Methods: This descriptive, cross-sectional study was conducted on 900 patients with positive P. aeruginosa cultures who were admitted to Imam Reza Hospital in Kermanshah, Iran during 2016-2018. Bacterial isolates were separated using laboratory tests, and the standard disc-diffusion method was used to assess antibiotic susceptibility based on the CLSI protocol. Data analysis was performed in SPSS version 24. Results: The majority of the P. aeruginosa-positive cases were isolated from the emergency ward (44.3%), intensive care unit (21.9%), blood samples (40.4%), and urine samples (18.7%). The highest antibiotic resistance was observed against cotrimoxazole, ceftriaxone, ampicillin, ampicillin-sulbactam, nitrofurantoin, nalidixic acid, cefazolin, and cefixime. In addition, ciprofloxacin and imipenem were the most effective antibiotics against P. aeruginosa with the sensitivity of 68.1% and 57.2%, respectively. Conclusions: According to the results, P. aeruginosa had high resistance against antibiotics such as cotrimoxazole and ceftriaxone. Therefore, these antibiotics should be used correctly and reasonably, and epidemiological studies in this regard should be focused on proposing national programs to prevent the further spread of antibiotic resistance.

Antibacterial Activity of Eight Medicinal Plants against Multidrug Resistant Escherichia coli and Salmonella spp. isolated from Broiler Meat

The excess use of antimicrobial agents in the poultry industry is a significant reason for the gradual spread and increasing level of multidrug resistance bacteria. This article is based on a study in which the antibacterial activity of aqueous, methanolic, ethanolic and acetonic extracts of eight medicinal plants were evaluated by standard disc diffusion method against multidrug resistant Escherichia coli and Salmonella spp. isolated from broiler meat. The multidrug resistance was checked by commercially available antibiotics using standard disc diffusion method. The results have indicated that the ethanolic extract of Boerhaavia diffusa showed maximum zone of inhibition against Escherichia coli, while Asparagus racemosus showed maximum zone of inhibition against Salmonella spp. Other experimental plant extracts had showed moderate activity against these multidrug-resistant bacteria, which can also be considered as potential source of active beneficial phytochemicals. Proper management and application of these plant extracts may be a wonderful alternative of commercially available antibiotic to minimize the risk.

Nutrient Analysis and Antimicrobial Activities of the Leaves and Fruit Pulp Extracts of Tetrapluera tetraptera on Clinical Bacteria Isolates

Introduction: Plants are known to contain numerous phytochemicals with potential antimicrobial activity. Aim: Nutritional, phytochemical and antimicrobial activities of the leaves and the fruit pulp extracts of Tetrapluera tetraptera was carried out. Methodology: Collection and identification of isolates and plants parts, and preparation of extracts and nutrient (proximate, vitamins and minerals and anti-nutrients) evaluations were all done using standard protocols previously reported. Evaluations of phytochemicals were carried out using crude screening, quantification and gas chromatography coupled to mass spectrophotometer for a robust analysis. Antimicrobial activities were evaluated using the standard disc method and chloramphenicol as control. Results: The results revealed varying amounts of proximate nutrients (ash, fibre, moisture, carbohydrate, protein and fat) in both samples. Vitamin analysis showed the presence of vitamin A, total and soluble vitamin C, niacin, riboflavin and thiamin in both samples. Furthermore, both samples had minerals such as Na, K, CA, P, Mg, Zn, Fe, and Cu, and K, Na, Ca, Mg, P, Fe, Zn and Cu in order of decreasing abundance in the fruit pulp and leaves, respectively. Both samples showed the presence of permissible levels of anti-nutrients compared to edible vegetables. Using all three methods, several phytochemicals such as terpenes, alkaloids, flavonoids, polyphenol, organic and fatty acids, amongst other in various amounts were obtained in the samples. Antimicrobial activities against identified clinical isolates used in this study which were Escherichia coli, Staphylococcus aureus and Proteus spp with both extracts ranged from 12.78±0.03 to 17.34±0.34 mm. Conclusion: Given the rising cases of antimicrobial resistance and absence of newer antibiotics, the antimicrobial activity of our study plant is worth further evaluations.

The Novel Quantitative Assay for Measuring the Antibiofilm Activity of Volatile Compounds (AntiBioVol)

Herein, we present a new test, dubbed AntiBioVol, to be used for the quantitative evaluation of antibiofilm activity of volatile compounds in vitro. AntiBioVol is performed in two 24-well plates using a basic microbiological laboratory equipment. To demonstrate AntiBioVol usability, we have scrutinized the activity of volatilized eucalyptus, tea tree, thyme essential oils, and ethanol (used for method suitability testing) against biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. We have also compared AntiBioVol with the standard disc volatilization method, placing a special stress on evaluating the impact of various technical parameters on the outcomes of the latter method. The obtained results indicate that AntiBioVol allows analyzing the antibiofilm activity of volatile compounds in a high number of repeats and provides semi-quantitative or quantitative results of high repeatability. In comparison to disc volatilization, AntiBioVol is a more space- and cost-effective method that allows analyzing various types of microbial aggregates. Moreover, we have indicated that the possible reasons for the discrepancies in the results obtained by means of the standard disc volatilization method may be related to various parameters of the testing dishes used (height, volume, diameter) and to various volumes of the agar medium applied. In turn, the application of a 24-well plate and a strictly defined AntiBioVol protocol provide a higher control of experimental conditions. Therefore, the application of AntiBioVol may enable an optimization of and introduction of volatile compounds to the fight against infective biofilms.

Modelling the spectral energy distribution of super-Eddington quasars

ABSTRACT We develop a broad-band spectral model, agnslim, to describe super-Eddington black hole accretion disc spectra. This is based on the slim disc emissivity, where radial advection keeps the surface luminosity at the local Eddington limit, resulting in L(r) ∝ r−2 rather than the r−3 expected from the Novikov-Thorne (standard, sub-Eddington) disc emissivity. Wind losses should also be important but these are expected to produce a similar radiative emissivity. We assume that the flow is radially stratified, with an outer standard disc, an inner hot Comptonizing region and an intermediate warm Comptonizing region to produce the soft X-ray excess. This gives the model enough flexibility to fit the observed data, but with the additional requirement of energy conservation to give physical constraints. We use this to fit the broad-band spectrum of one of the most extreme Active Galactic Nuclei, the Narrow Line Seyfert 1 RX J0439.6−5311, which has a black hole mass of $(6\sim 9)\times 10^6\, \mathrm{M}_\odot$ as derived from the H β line width. This cannot be fit with the standard disc emissivity at this mass, as even zero spin models overproduce the observed luminosity. Instead, we show that the spectrum is well reproduced by the slim disc model, giving mass accretion rates around (5 ∼ 10) × Eddington limit. There is no constraint on black hole spin as the efficiency is reduced by advection. Such extreme accretion rates should be characteristic of the first Quasars, and we demonstrate this by fitting to the spectrum of a recently discovered super-Eddington Quasar, PSO J006 + 39, at z = 6.6.