Production and Assessment of AZ91 Reinforced with Nano SiC through Stir Casting Process

Magnesium, a light weight alloy used in multiple engineering industrial applications because of its good Physical, Chemical and Thermal characteristics. Magnesium composites play an important role in partial or entire replacement of numerous alloys.This current work deals with Nano silicon carbide of about 100nm was incorporated with AZ91magnesium alloy through liquid state composite processing. Two samples are made using 0% Nano SiC and 3% Nano SiC and are characterized through tensile test in Universal Testing Machine, Micro hardness test in Vickers hardness tester and Microstructure in Optical Microscopy. From the study it was clear that there is a peak increase in hardness of about 36% when compared to as casted AZ91.

Seasonal fluctuations C. pneumonia and M. pneumoniae infections among children with acute respiratory diseases

The article presents the results of the analysis of the main trends in the epidemic process for mycoplasmal and chlamydial infections among children with respiratory diseases over several seasons from November 2018 to July 2020 based on the results of testing 617 serum samples. The data obtained indicate that, along with seasonal fluctuations in seropositivity, there is an epidemiological season from December 2019 to January 2020, characterized by a peak increase in the number of seropositive cases, the largest number of which was detected among school-age children hospitalized for community-acquired pneumonia.

An exploratory Integrated Moving Average Time Series Model of the initial outbreak of COVID-19 in six (6) significantly impacted Countries

The 2019 Novel Coronavirus SARS-CoV-2 (COVID-19) is a single-stranded RNA virus that has threatened the lives of humans all over the globe. Government officials, policy makers and public health officials have been scrambling and struggling to flatten the curve to decelerate the prevalence and spread of COVID-19 given the significant economic destruction of the spread of the virus. Most flatten the curve models are based on Compartmental Models. This preliminary research is based on six (6) selected countries significantly impacted by COVID-19 and endeavors to build a new model based on moving averages lagged at different time periods to better hone in on the time the COVID-19 begins to decelerate using the date of first reported case and date of first reported death. This new model, the Consistent Deceleration Model (CDM) is based on each individual countrys date of Peak Increase in Mortality Rate (PINC MR) and the Moving Average since the peak increase in mortality rate (MA POSTINC). The CDM can be utilized of one of many quantitative tools to determine the strength of the deceleration of an infectious outbreak.

Attenuated Cardiovascular Responses to the Cold Pressor Test in Concussed Collegiate Athletes

Context Cardiovascular responses to the cold pressor test (CPT) provide information regarding sympathetic function. Objective To determine if recently concussed collegiate athletes had blunted cardiovascular responses during the CPT. Design Cross-sectional study. Setting Laboratory. Patients or Other Participants A total of 10 symptomatic concussed collegiate athletes (5 men, 5 women; age = 20 ± 2 years) who were within 7 days of diagnosis and 10 healthy control individuals (5 men, 5 women; age = 24 ± 4 years). Intervention(s) The participants' right hands were submerged in agitated ice water for 120 seconds (CPT). Main Outcome Measure(s) Heart rate and blood pressure were continuously measured and averaged at baseline and every 30 seconds during the CPT. Results Baseline heart rate and mean arterial pressure were not different between groups. Heart rate increased throughout 90 seconds of the CPT (peak increase at 60 seconds = 16 ± 13 beats/min; P < .001) in healthy control participants but remained unchanged in concussed athletes (peak increase at 60 seconds = 7 ± 10 beats/min; P = .08). We observed no differences between groups for the heart rate response (P > .28). Mean arterial pressure was elevated throughout the CPT starting at 30 seconds (5 ± 7 mm Hg; P = .048) in healthy control individuals (peak increase at 120 seconds = 26 ± 9 mm Hg; P < .001). Mean arterial pressure increased in concussed athletes at 90 seconds (8 ± 8 mm Hg; P = .003) and 120 seconds (12 ± 8 mm Hg; P < .001). Healthy control participants had a greater increase in mean arterial pressure starting at 60 seconds (P < .001) and throughout the CPT than concussed athletes (peak difference at 90 seconds = 25 ± 10 mm Hg and 8 ± 8 mm Hg, respectively; P < .001). Conclusions Recently concussed athletes had blunted cardiovascular responses to the CPT, which indicated sympathetic dysfunction.

620. Sub-MIC Concentrations of Levofloxacin and Delafloxacin Enhance Staphylococcus aureus Biofilm Formation: Significance of Maximizing Exposure

Background Fluoroquinolones are utilized in Staphylococcal prosthetic joint infections due to their anti-biofilm activity. When antibiotic dosing is not optimized or antibiotics do not reach the site of infection, additional virulence factors may upregulate. We aimed to determine whether exposure to sub-MIC concentrations of levofloxacin and delafloxacin affect biofilm formation in Staphylococcus aureus. Methods This study utilized 50 diverse methicillin-susceptible S. aureus (MSSA) clinical isolates collected between 2004 and 2018. Sources included blood, skin/tissue, bone, and joint fluid. Minimum inhibitory concentrations and minimum bactericidal concentrations were identified according to CLSI. Biofilm assays were conducted as previously described by our program. Biofilm quantification was categorized as strong (OD570 ≥ 2), moderate (OD570 ≥ 1 and < 2), or weak (OD570 < 1). Prevention assays were conducted with the addition of increasing concentrations of delafloxacin or levofloxacin. We evaluated the amount of isolates that demonstrated increased biofilm formation in the presence of sub-MIC concentrations and extent of biofilm enhancement. Percent change was calculated between OD570 of the isolate growth control without antibiotic exposure and peak biofilm OD570 when exposed to the antibiotic. Results Of the 50 MSSA isolates, 14 (28%) exhibited moderate/strong formation and 36 (32%) exhibited weak biofilm formation. 52% and 58% of the isolates demonstrated a ≥50% increase in formation when exposed to sub-MIC concentrations of delafloxacin and levofloxacin, respectively. None of the strong biofilm formers demonstrated a ≥50% peak increase in formation when exposed to the antibiotics. Of the isolates that demonstrated a ≥50% peak increase, the average percent change was 267% (±29) with levofloxacin and 258% (±33) with delafloxacin. Conclusion Sub-MIC concentrations of delafloxacin and levofloxacin increased biofilm formation in S. aureus isolates that normally exhibit weak or moderate biofilm formation when not in the presence of antibiotics. Maintaining appropriate fluoroquinolone concentrations at the site of action is critical in preventing enhancement of biofilm formation. Further research is needed to identify the mechanism behind this increase. Disclosures All authors: No reported disclosures.

Effects of non-Newtonian lubricants and elastic coating on transient elastohydrodynamic lubrication at impact squeeze loading

This study explores the effects of non-Newtonian lubricants on elastohydrodynamic lubrication with coating at impact and rebound loading using power law lubricants. The coupled transient modified Reynolds, rheology, elasticity deformation, and ball motion equations are solved simultaneously, thus obtaining the transient pressure profiles, film shapes, normal squeeze velocities and accelerations. The effect of the flow index ( n) is equivalent to enhancing the lubricant viscosity, also enlarging the damper effect. The simulation results reveal that the film thickness, the primary peak, and the secondary peak increase with increasing the flow index. The greater the flow index is, the earlier the dimple form, and the smaller the maximum value of the impact force is. The rebounding velocity and the peak value of acceleration increase with decreasing the flow index. Moreover, this research possesses academic innovation and industrial application.

Efficiency of 3% Non-epinephrine Mepivacaine Application During Intraligamentary Anesthesia With Positive and Negative Aspiration in Pain Sensitivity to Electric Current of Young Subject`s Upper Anterior Teeth Pulp:

Background: Separation methods of local anesthesia to diffuse and vascular must significantly affect the clinical effect of adrenaline containing local anesthetic (mepivacaine). The aim of this prospective, randomized, controlled studies µAde was to compare the degree of anesthesia of intact upper lateral incisor the cartridge ¼ 3% mepivacain without epinephrine in the group after the infiltration and after intraligamentary anesthesia (ILA) in the experimental group. Methods: Anesthesia performed computer syringe Sleeper One 86 subjects aged 20-23 years. In all cases, aspiration was performed. With pulp tester IVN-01 measured the pain threshold incisors and canines in microamperes during the anesthetic effect. Results: Reference level of all researched teeth (86 subjects) was ranged from 1 to 10 µA. Uniform pain threshold increase to 95 (±20) µA by 5 min. watched during infiltration anesthesia then this value gradually descended to reference level (by 20 min.). Peak single increase of pain threshold to 55 (±8,9) µA occurred immediately after 1st minute of ILA, then this value subsequently drops to reference level (10 µA) by 20 minutes. Difference between groups of infiltration and intraligamentary anesthesia (ILA+ red) and (ILA – green) presented on Chart 6. Conclusions: Infiltration anesthesia with mepivacaine without epinephrine smoothly diffusely increased the pain threshold of the front teeth, reaching a significant, maximum effect by 5 minutes. Intraligamentary injection immediately after administration created a peak increase in pain sensitivity at a lower level, almost without the participation of the diffuse component.

Experimental study of the progressive collapse mechanism of excavations retained by cantilever piles

An increasing number of catastrophic progressive collapses of deep excavations have occurred throughout the world. However, the research on progressive collapse mechanisms is limited. In this paper, two categories of model tests were conducted to investigate the mechanism of partial collapse (sudden failures of certain retaining piles) and progressive collapse. The model test results show that partial collapse can cause a sudden increase in the bending moments of adjacent piles via an arching effect. The load-transfer coefficients are defined to be equal to the peak increase ratios of the maximum bending moments in adjacent piles (peak moments caused by collapse over the values before the collapse). When the maximum load-transfer coefficient is larger than the bearing capacity safety factor of the piles, the partial failure will lead to progressive collapse. The influential factors of the progressive collapse mechanism, such as the partial collapse extent, excavation depth, and capping beam, were also investigated. During progressive collapse, the previous failed pile could cause new stress arching; simultaneously, the soil behind certain nearest intact piles could become loosened and destroy the arch springing of the stress arching, causing the progressive collapse to cease gradually.

Numerical Analysis of low voltage Arc Motion Process at Various Frequencies

A three-dimensional (3D) magneto-hydro-dynamic (MHD) model of air arc plasma is built to investigate the frequency effects on the arc motion process with different number of splitter plates. Based on this model, the arc voltage and current density are obtained. The arc motion time is normalized with the frequency and compared at different numbers of splitter plate. The result shows that the normalized time and the arc voltage peak increase with increases of the number of splitter plate.

Regional temperature and quantitative cerebral blood flow responses to cortical spreading depolarization in the rat

Regional temperature and quantitative regional cerebral blood flow responses to cortical spreading depolarization in the rat were continuously monitored in the same tissue using a microfabricated thermal diffusion sensor that recalibrates and measures in 5-s cycles. The regional cerebral blood flow response had four phases, including early hyperemia (peak: 226% of baseline; duration: 113.1 ± 14.4 s) and late oligemia (minimum: 57%, duration: 28.4 ± 3.7 min). Temperature rose with the start of the regional cerebral blood flow response to a peak increase of 0.28 ± 0.06℃ and returned to baseline near the start of oligemia. This technology may be useful for multimodal monitoring in both the laboratory and clinic.