Study of the Isochronal Annealing of High Pressure Die-Cast Magnesium Alloy AZ91 by Positron Annihilation Lifetime Technique

Key words: Positron lifetime; isochronal annealing; AZ91 alloy; microhardness; microstructure INTODUCTION Magnesium alloys (light alloys) are of increasing attention for transport applications in the automotive and aerospace industry. The most popularly used magnesium alloys are those based essentially on the Mg-Al system, such as AZ91, AM60B and AM50A. In addition, the poor elevatedtemperature properties of low-cost magnesium alloys have now become a critical issue for widespread applications of magnesium alloys [1] . Several investigations have been performed using positron annihilation lifetime (PAL) for studying defects in magnesium and magnesium alloys [2-6]. Positron Annihilation Lifetime (PAL) is a specific technique for the detection of open volume defects such as vacancies, vacancy clusters, dislocations, grain boundaries in materials (metals and alloys) and free volumes for polymers Mg, 9%Al -and 1%Zn (AZ91) alloy is the most widely used commercial Magnesium alloy and has a good combination of castability, mechanical strength and ductility. Currently, AZ91 alloy is used mainly in the high pressure die-casting (HPDC) form for structural components in the automobile industry. HPDC is a well established process, which is of high efficiency and low cost. However, the HPDC components contain a substantial amount of porosity due to gas entrapment during die-filling and hot tearing during the solidification in the die cavity. Such porosity not only affects mechanical properties, but also denies the opportunity for property enhancement by subsequent heat treatmen

Incidence of cotton whitefly Bemisia tabaci (Gennadius, 1889) (Hemiptera: Aleyrodidae) infesting cucumber (Cucumis sativus L.) cultivars with reference to cultivar susceptibilities

Field experiments were carried out in Egypt to investigate the infestation rates of cotton whitefly Bemisia tabaci on five cultivars of cucumbers Cucumis sativus during two consecutive late summer seasons from 11 August to 28 October 2015 and 2016. The susceptibilities of the cultivars to infestation by this pest were examined. The five cultivars – Hayl, Nems, Beit Alpha Zena, Bahi and Wafier – were cultivated on a private farm in Mansheyet Saqqara village, Giza. The results showed that whitefly infestation peaks were high in September and October, but low in November in both seasons. The population densities of Bemisia tabaci eggs, nymphs and adults on all the cultivars were slightly higher in 2015 than in 2016. Numbers of B. tabaci eggs, nymphs and adults rose with increasing the temperatures in both seasons, and mean numbers of nymphs and adults also increased with decreasing RH% on all the cultivars. The combination of temperature and humidity was an important regulatory factor affecting B. tabaci development. The results of this study showed that high infestation peaks of B. tabaci occurred in September and October of both seasons. The present results were used to classify the degrees of susceptibility of these cucumber cultivars to B. tabaci infestation as susceptible (S), low resistant (LR) and moderately resistant (MR). It is important that these degrees of susceptibility be referred to the degree of resistance of each cultivar to insect infestation

Experimental investigation and theoretical evaluation of proton induced nuclear reactions on nickel

The cross-sections for proton-induced nuclear reactions on natural nickel were experimentally measured for the natNi(p,x)60,61,64Cu, natNi(p,x)55,57,58Co and natNi(p,x)57Ni reactions from their respective thresholds up to 17 MeV proton energy. The stacked-foil technique in combination with HPGe γ-ray spectroscopy was used. Three codes were used in the theoretical calculations namely ALICE-IPPE, EMPIRE-3.2.2 and TENDL-2017. Comparison of the present results with the earlier reported experimental data and with the code results were carried out

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit