CIRCULAR TEST STRUCTURES FOR DETERMINING THE SPECIFIC CONTACT RESISTANCE OF OHMIC CONTACTS

Though the transport of charge carriers across a metal-semiconductor ohmic interface is a complex process in the realm of electron wave mechanics, such an interface is practically characterised by its specific contact resistance. Error correction has been a major concern in regard to specific contact resistance test structures and investigations by finite element modeling demonstrate that test structures utilising circular contacts can be more reliable than those designed to have square shaped contacts as test contacts become necessarily smaller. Finite element modeling software NASTRAN can be used effectively for designing and modeling ohmic contact test structures and can be used to show that circular contacts are efficient in minimising error in determining specific contact resistance from such test structures. Full semiconductor modeling software is expensive and for ohmic contact investigations is not required when the approach used is to investigate test structures considering the ohmic interface as effectively resistive

Exploring the repurposed role of solithromycin as an antivirulence agent against Staphylococcus aureus and its resistant variants

IntroductionStaphylococcus aureus is a bacterium that can cause various infections. The rise in Staphylococcal-resistant infections has led to the need for new treatments. The accessory gene regulator (agr) quorum-sensing system, which regulates the expression of genes involved in hemolysin, protease, and biofilm production, has been implicated in the virulence of S. aureus’s pathological characteristics.ObjectivesThis study investigates the potential of Solithromycin (SOL), a next-generation macrolide with broad-spectrum activity, to be repurposed as an antivirulence agent against S. aureus, MRSA, and ΔagrA strains.MethodsUsing various antibacterial assays, the antibacterial and antivirulence activities of SOL were evaluated against S. aureus, MRSA, and ΔagrA strains. The sub-inhibitory concentration MIC50 of SOL was tested for anti-virulence activity by assessing motility, biofilm formation, hemolysin, and protease production. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to visualize biofilm morphology. Conventional PCR was used to detect virulence genes following SOL treatment.ResultsSOL demonstrated significant antibacterial efficacy against S. aureus, MRSA, and ΔagrA strains with MIC90 (0.8 μg/mL) and MIC50 (0.4 μg/mL). SOL decreased S. aureus motility at MIC50 but had no effect on MRSA and ΔagrA strains. Hemolysin and protease activities were unaffected in all the tested strains. SEM and CLSM revealed significant reductions in biofilm formation and thickness. SOL at MIC90 and MIC50 reduced Congo red staining intensity. MIC50 inhibited MRSA and ΔagrA biofilms by 36.6 and 56.4%, respectively, with no significant effect on S. aureus biofilms in the crystal violet assay. PCR showed no leukocidin gene in the treated strains.DiscussionThis study highlights the potential of SOL as an antivirulence agent, emphasizing the importance of targeting regulators, such as ΔagrA, in managing S. aureus infections

Analysis of Oscillations during Out-of-Step Condition in Power Systems

Power systems interconnected by weak tie lines can be subject to low-frequency oscillations because of disturbances which excites the low-frequency modes of the system; furthermore, these oscillations can be stable or unstable. The latter, if not treated, can cause severe oscillations that divide the network into smaller groups which oscillate against each other, leading to out-of-step (OOS) condition in the network. The detection of OOS condition is a challenge for power system operators in real time as it is difficult with conventional measuring instruments, to identify the instant at which the bus voltage angle between two areas connected by tie line falls out of synchronism. Conventionally, the detection of OOS condition has been carried out with impedance-based relays along with power swing blocking. With the advent of synchrophasor-based measurement units, it is now possible to measure the bus voltage angle in real time leading to direct detection of OOS condition in power system and intentional islanding. In this article, a systematic analytical study and EMT time-domain simulation study have been performed to simulate OOS condition in the power systems, and its detection is based on the voltage angle difference with wide-area measurement systems (WAMSs). The article has been carried out on a single machine infinite bus (SMIB) to monitor generator OOS, Kundur’s two-area system to detect interarea OOS, and the IEEE39 bus system to identify OOS condition and with a new algorithm. Time-domain simulation studies carried out with OPAL-RT real-time simulator in HYPERSIM environment corroborates with analytical results.</jats:p

Pharmacokinetics Parameters of Diagoxin among Saudi Patients in Qassim Region, Saudi Arabia

Background: The pharmacodynamic effects of digoxin are susceptible to multiple factors, most notably, heart uptake of the digoxin dose and its concentration in the serum. Another important factor to mention is the renal function state of an individual. Objective: In this study, we aimed to develop a simple algorithm based on subsets of clinically relevant information, which will help to personalize digoxin based on pharmacokinetic (PK) approach which can help in marketing the appropriate utilization of this medication. Methods: This was a retrospective chart review and analysis of 48 patients who were admitted to the Drug and Poison Information center in Buraidah, Saudi Arabia, between January 2016 and April 2019. All pharmacokinetic parameters were added according to the C-peaks and C-troughs. MONOLiX® was used for data pharmacokinetic analysis. Results: Twenty-seven (56%) were males and twenty-one (44%) were females with an average age of 63.6 years across both genders. The mean volume of distribution was 496.6 litres with an average clearance of 6.6 L/h. For females, their average volume of distribution was slightly higher than that for males (526 litres compared to 473 litres). In addition, the clearance rate between both genders showed a 2.1 litre/hour discrepancy (7.8 L/h for females compared to 5.7 L/h for males). Conclusion: In order to individualize the digoxin dosage regimens, this model can be used to predict digoxin serum concentration. Further studies are needed to clarify the effects of nutritional status and co-administration of medications on digoxin pharmacokinetics. </jats:sec