Modification of as-cast Al-Mg/B4C composite by addition of Zr

Zirconium was used in Al-Mg/B4C composite to improve compocasting efficiency by increasing particle incorporation. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) results revealed that by addition of zirconium a reaction layer containing Zr, Al, B and C is formed on the interface of B4C-matrix. X-ray diffraction (XRD) analysis of extracted particles unveiled that the ZrB2 phase is the main constituent of this layer. Formation of ZrB2 is an exothermic reaction which can rise temperature locally around particles and agglomerates. Rising temperature around agglomerates in conjunction with turbulent flow of melt facilitates agglomerates wetting and dissolving into molten aluminum. As the result, final product contains more uniformly distributed B4C particles. Besides enhancing compocasting efficiency, addition of Zr and formation of reaction layer by improving particle matrix bonding quality, led to increase in ultimate tensile strength and elongation of the composite around 8% and 30%, respectively. SEM observations of the fracture surfaces confirmed that a proper bonding presents at the interface of particles and matrix in presence of Zr.Peer ReviewedPostprint (author's final draft

Allele and genotype frequencies of -lactoglobulin gene in Iranian Najdi cattle and buffalo populations using PCR-RFLP

In modern programmes of animal breeding, the polymorphism of the milk proteins can be used as marker systems.  -Lactoglobulin is the major milk whey protein in the ruminants. Studies have indicated that this protein is polymorphic in the many breeds of cattle. This is the result of a single base pair substitution in the -lactoglobulin gene that also give rise to the Hae III restriction fragment length polymorphism. The aim of this work was to analyze the genotype distribution of -lactoglobulin in Iranian Najdi cattle and buffalo. Blood samples were supplied from 80 Najdi cattle and 80 buffalo from different cities of Khouzestan province. Polymerase chain reaction was applied to amplification of a 247 bp fragment of exon and intron IV of bovine -lactoglobulin gene. The Hae III enzyme was used for restriction of the PCR products. The digested products were separated by electrophoresis on 2.5% agarose gel. The allele B of -Lactoglobulin occurred at a higher frequency than the allele A in both Najdi cattle and buffalo. The genotype frequencies of AA, AB, and BB in Najdi cattle and buffalo were 0, 0.175, 0.825 and 0.04, 0.3, 0.66 respectively. Frequencies of A and B alleles were 0.0875 and 0.9125, and 0.1875 and 0.8125 in Najdi cattle and buffalo, respectively. The deviation from Hardy-Weinberg equilibrium was not detected in any of those animals. Detection of heterozygosity indicator evidence on low level of heterozygosity and genetic variability in both population

Dynamic deformation response of Al-Mg and Al-Mg/B4C composite at elevated temperatures

The dynamic deformations at high temperatures of Al-3 wt%Mg alloy and Al-3 wt%Mg/B4C composites with different volume fractions and particle sizes were studied using a dilatometer deformation instrument and a split Hopkinson pressure bar operating at strain rates of 10–1000 1/s. A comprehensive analytical procedure was developed to correct the effects of adiabatic heating, friction at interface of the specimen and bars, and strain rate variation, on flow stress curves. Then based on corrected data, a physical based constitutive equation was developed for modeling and prediction of flow stress. It was observed that composites in comparison with single phase alloy, after initial straining, showed lower hardening rate which is unexpected. EBSD micrographs and finite element analysis were used to investigate microstructural evolution and deformation condition around particles. It was concluded that particle fracture during deformation which is more expectable in larger particles, and also higher adiabatic heating in composite and not recrystallization related phenomena, are the main reasons for softening of stress flow curves at large deformation.Peer ReviewedPostprint (author's final draft

Microstructural investigation of Al-Mg/B4C composite deformed at elevated temperature

The microstructure evolution of Al-3wt.%Mg reinforced with 10¿vol% B4C during isothermal compression at temperatures ranging 300–500¿°C at strain rates of 0.001–10 s-1 was investigated by electron backscatter diffraction (EBSD). According to the results, at strain rates lower than 0.01 s-1 and temperatures higher than 400¿°C, the grain size distribution in the microstructure is uniform, dynamic recovery is the predominant softening mechanism and continues recrystallization through lattice rotation is responsible for grain refinement. However, during deformation at higher strain rates or lower temperatures, deformation zones appeared in special locations around particles where microstructure is formed by recovered and hardened grains, and particle stimulating nucleation leaded to partially discontinues dynamic recrystallization which in turns promoted finer average grain and sub-grain size than those in single phase Al-Mg alloy. Moreover, it was found that the variation of grain and sub-grain size with deformation parameters (Zener-Holloman parameter (Z)) can be described by a power law type equation rather than by an initially expected exponential expression.Peer ReviewedPostprint (author's final draft

Chest Injury Evaluation and Management in Two Major Trauma Centers of Isfahan Province, IR Iran

Background:: Chest trauma is responsible for 50% of deaths due to trauma. This kind of death usually occurs immediately after the trauma has occurred. Objectives:: The aim of this study was to evaluate the various aspects of chest trauma in patients admitted to two main trauma centers located in the Isfahan Province, Iran. Patients and Methods:: During a six month period, a cross-sectional study of 100 patients who had sustained a chest injury was carried out. Data, including; age, sex, time of accident, trauma mechanism, organ injury, hospitalization length, complications, and patient outcomes were recorded and analyzed. Results:: The mean ages of the patients were 24.7 ± 3.1 years. Men were injured four times more often than the women. Blunt trauma was the most common type of injury. The incidence of hemothorax was 38% in blunt traumas, and 45% (P = 0.01) in penetrating ones. The incidence of pneumothorax was 43% in blunt traumas and 20% in penetrating ones (P = 0.03). The length of hospitalization was 7.2 ± 3.2 days for blunt and 10.1 ± 3.1 days for penetrating chest traumas. Five patients (5%) died during hospitalization, three of those deaths were due to arterial injuries and two cases were due to lung contusions. Conclusions:: Since hemothorax is the main complication of blunt chest trauma in young men, we recommend that special consideration needs to be made to any case of chest trauma, especially blunt chest injuries

Hot deformation behavior and flow stress modeling of Ti–6Al–4V alloy produced via electron beam melting additive manufacturing technology in single β-phase field

The hot working behaviour of additively manufactured Ti–6Al–4V pre-forms by Electron Beam Melting (EBM) has been studied at temperatures of 1000–1200 °C and strain rates of 0.001–1 s−1. As a reference, a wrought Ti–6Al–4V alloy was also analyzed as same as the EBM one. In order to investigate the hot working behaviour of these samples, all the data evaluations were carried out step by step, and the stepwise procedure was discussed. No localized strain as a consequence of shear band formation was found in the samples after the hot compression. The flow stress curves of all the samples showed peak stress at low strains, followed by a regime of flow softening with a near-steady-state flow at large strains. Interestingly, it is found that the initial microstructure and porosity content as well as the chemistry of material (e.g. oxygen content) as being possible contributors to the lower level of flow stress that could be beneficial from the industrial point of view. The flow softening mechanism(s) were discussed in detail using the microstructure of the specimens before and after the hot deformation. Dynamic Recrystalization (DRX) could also explain the gentle oscillation in the appearance of the flow softening curves of the EBM samples. Moreover, the hot working analysis indicated that the activation energy for hot deformation of as-built EBM Ti–6Al–4V alloy was calculated as ~193.25 kJ/mol, which was much lower than the wrought alloy (229.34 kJ/mol). These findings can shed lights on a new integration of metal Additive Manufacturing (AM) and thermomechanical processing. It is very interesting to highlight that through this new integration, it would be possible to reduce the forging steps and save more energy and materials with respect to the conventional routes

Pre-Hospital Trauma Care in Road Traffic Accidents in Kashan, Iran

Background: Iran has one of the highest rates of road traffic accidents (RTAs) worldwide. Pre-hospital trauma care can help minimize many instances of traffic-related mortality and morbidity. Objectives: The aim of this study was to assess the characteristics of pre-hospital care in patients who were injured in RTAs, admitted to hospital. The focus was mainly directed at evaluating pre-hospital trauma care provided in city streets and roads out of the city. Patients and Methods: This retrospective study was carried out on all trauma patients, transported by the emergency medical service (EMS) system, who were admitted to Kashan Shahid-Beheshti hospital during the period from March 2011 to March 2012. The patients’ demographic data, location of accident, damaged organs, mechanism of injury, injury severity, pre-hospital times (response, scene, transport), pre-hospital interventions and outcomes, were extracted from the data registry and analyzed through descriptive statistics using SPSS 18 software. Results: Findings of this study showed that, 75% of RTAs occurred on city streets (n = 1 251). Motor-car accidents were the most frequent mechanism of RTA on city streets (n = 525) (42%), while car rollover was the most frequent mechanism of RTA on roads out of the city (n = 155) (44.4%). The mean pre-hospital time intervals (min); response, scene, and transport for all patients were 6.6 ± 3.1, 10.7 ± 5 and 13 ± 9.8, respectively. The mean pre-hospital time intervals (response, scene, transport) in roads out of the city were higher than those in city streets. There was a significant difference (P = 0.04) in the mortality rates due to RTAs between city streets (n = 46) and roads out of the city (n = 32). Conclusions: In comparison with road traffic accidents on city streets, trauma patients in RTAs on roads out of the city have longer pre-hospital time intervals and more severe injuries; therefore this group needs more pre-hospital resuscitation interventions

Effect of vitamin D vaginal suppository on sexual functioning among postmenopausal women: a three-arm randomized controlled clinical trial

Objective: Vaginal atrophy, the second most common complication of menopause, can lead to sexual dysfunction. This study evaluated the effect of a vitamin D vaginal suppository on sexual functioning in postmenopausal women. Methods:This three-arm randomized controlled trial was conducted between August 2019 and August 2020. The sample comprised 105 postmenopausal women who were referred to comprehensive health service centers to receive postmenopausal care. The inclusion criteria were as follows: (i) being menopausal for at least 1 year, (ii) being married, (iii) being sexually active, and (iv) having sexual desire. Participants were randomly assigned to three groups for 8 weeks of treatment: intervention (vaginal suppository containing 1,000 units of vitamin D3), placebo (vaginal suppository placebo), or control (no treatment). The main outcome measure was sexual functioning, which was assessed using the Female Sexual Function Scale (FSFI) 4 times during the study (i.e., 1 month before the intervention, immediately after the intervention, 1 month after the intervention, and 2 months after the intervention). Results: Immediately and 1 month after the trial, the intervention group had the highest FSFI score, followed by the placebo group, both of which were significantly higher than those of the control group (P<0.05). At the 2-month follow-up, the intervention and placebo groups had similar FSFI scores (P=0.08), both of which were significantly higher than those in the control group (P=0.001 and P=0.03, respectively). Conclusion: Vitamin D vaginal suppositories were more effective at improving sexual functioning among postmenopausal women in the short-term and appeared to prevent aging-related sexual functioning decline in the long term