Use of steel slag in concrete mixtures

The recent unprecedented growth in the building industry in the State of Qatar has created a pressing demand for construction materials. Needs for concrete, being the major construction material has grown with the rapidly growing construction sector. Aggregate generally occupy about 70-80% of the volume of concrete used in buildings. The needs for alternative sources of aggregates are pressing. Steel slag, which is a by-product of steel manufacturing, could be an alternative solution. This paper presents the results from experimental works completed at Qatar University to check the applicability of using steel slag aggregates in concrete mixes in Qatar. Five trial concrete mixes were prepared.  One concrete mix composing of 100% gabbro coarse aggregates was designated as the control mix. Four other concrete mixes were prepared and they contained 100%, 75%, 50%, and 25% partial replacement of gabbro aggregates with slag aggregates, by weight. The concrete mix was proportioned to have a 28-day compressive strength of 35 MPa. The water-to-cement ratio was kept constant at 0.58 for all of the five mixes. All mixtures were cured for 7, 28, and 90 days.  No admixtures or additives were used in these mixes. The data indicate that steel slag has a promising potential to be used as a partial replacement for conventional aggregates in concrete. The emphasis of the work in the initial phase of this study was on the feasibility of utilizing steel slag aggregates in concrete, as a total or partial replacement of gabbro aggregate, used in construction in the State of Qatar by studying the properties of fresh and hardened concrete. Tests were conducted on concrete samples made of different aggregates to determine their acceptability for use in concrete. The different mixes were tested to determine compressive strength, splitting tensile strength, flexural strength, air content, and bulk density. Laboratory results, obtained in the six months research project, indicated that steel slag alone or in combination with other virgin raw materials such as gabbro, sand, and others could find uses in road construction applications in the State of Qatar

Use of local discarded materials in concrete

Steel slag, a by-product of steel manufacturing, is generated in large quantities in Qatar. In fact, it is estimated that more than 400,000tons of steel slag are generated annually in the country. Gravel, resulting from washing sand, is also produced at more than 500,000tons/year in Qatar. Both materials are not efficiently used in the country and most of its aggregate (gabbro) needs are imported from neighboring countries. This paper presents the results obtained on the use of steel slag, gravel and gabbro in concrete. A total of nine concrete mixtures were prepared. One concrete mixture that contained 100% gabbro aggregate was considered as the control mix. Four concrete blends containing 100%, 75%, 50%, and 25% steel slag (by weight) were prepared as partial replacements of gabbro aggregates. Another four concrete mixtures containing 100%, 75%, 50%, and 25% gravel (by weight) were cast as partial replacements of gabbro aggregates. All samples were cured in a water tank for 7, 28 and 90days and then subjected to compressive, flexural and splitting tensile strength tests. All concrete mixtures prepared easily met the 28-day compressive strength design requirement of 28MPa. Best results were obtained for concrete prepared using 100% steel slag aggregates. Concrete cast using 100% gravel yielded lower strength results than the control mixture (100% gabbro). However, there was an increase in strength values with an increase in gabbro content in gravel/gabbro mixtures. Additional work is necessary to establish long-term performance, especially concerning what is reported in the literature about the expansive characteristics of steel slag aggregates when used in concrete. It should be noted that concrete cured for 90days in the water tank did not exhibit any reversal in strength.Slag Aggregate Producer, under Qatar University (QU) Research Grant No. QUEX-CENG-SAP-12/13-1. The Gulf Organisation for Research and Developmen

Prevalence and Predictors of Insulin Resistance in Non-Obese Healthy Young Females in Qatar

The state of Qatar suffers from diabetes epidemic due to obesity-associated metabolic syndrome. However, the prevalence of insulin resistance prior to obesity, which could play an important role in the high prevalence of diabetes, has not yet been described. This study aims to compare the prevalence of insulin resistance in apparently healthy non-obese and obese participants from Qatar and identify the predictors of insulin resistance in different body massindex(BMI)-groups. In this cross-sectional study, 150 young healthy females from Qatar were dichotomized into four groups (underweight, normal weight, overweight and obese) based on their BMI. Anthropometric measures as well as fasting plasma levels of lipids, adipokines, blood glucose and insulin were recorded. The prevalence of insulin resistance as per homeostatic model assessment of insulin resistance (HOMA-IR) was estimated and differences between insulin sensitive and insulin resistant were compared. Linear models were used to identify predictors of insulin resistance in every BMI group. Prevalence of insulin resistance in non-obese healthy females from Qatar ranges between 7% and 37%and increases with BMI. Overall, predictors of insulin resistance in the Qatari population are triglycerides/high-density lipoprotein (HDL) ratio and free fat mass but vary according to the BMI group. The main predictors were triglycerides in normal weight, triglycerides/HDL in overweight and triglycerides/HDL and interleukin-6 (IL-6) in obese individuals. The high prevalence of insulin resistance in non-obese Qataris may partially explain diabetes epidemic. Larger studies are warranted to confirm these findings and identify underlying causes for insulin resistance in non-obese individuals in Qatar, aiming at targeted intervention before diabetes onsetThis project was funded by Qatar University (grant number QUST-CAS-FALL-14\15-35). The publication of this article was funded by the Qatar National Library

Charged ultrafiltration membranes based on TEMPO-oxidized cellulose nanofibrils/poly(vinyl alcohol) antifouling coating

This study reports the potential of TEMPO-oxidized cellulose nanofibrils (T-CNF)/poly(vinyl alcohol) (PVA) coatings to develop functionalized membranes in the ultrafiltration regime with outstanding antifouling performance and dimensional/pH stability. PVA acts as an anchoring phase interacting with the polyethersulfone (PES) substrate and stabilizing for the hygroscopic T-CNF via crosslinking. The T-CNF/PVA coated PES membranes showed a nano-textured surface, a change in the surface charge, and improved mechanical properties compared to the original PES substrate. A low reduction (4%) in permeance was observed for the coated membranes, attributable to the nanometric coating thickness, surface charge, and hydrophilic nature of the coated layer. The coated membranes exhibited charge specific adsorption driven by electrostatic interaction combined with rejection due to size exclusion (MWCO 530 kDa that correspond to a size of ∼35–40 nm). Furthermore, a significant reduction in organic fouling and biofouling was found for T-CNF/PVA coated membranes when exposed to BSA and E. coli. The results demonstrate the potential of simple modifications using nanocellulose to manipulate the pore structure and surface chemistry of commercially available membranes without compromising on permeability and mechanical stability

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030