Calculation of the interaction between a complex turbulent shear layer and an external inviscid stream

Imperial Users onl

Mechanical and Thermal Properties of Polylactic Acid and Plasticized Polylactic Acid with Thermoplastic Sago Starch Blends

The aim of this study was to produce plasticized blends of Polylactic acid,to evaluate the effect of two plasticizers Triethyl citrate (TC) and thermoplastic sago starch (TSS) on the mechanical and thermal properties of PLA and to evaluate the combined effect of plasticizers (TC and TSS) on the mechanical and thermal properties of PLA.The biodegradable polymer blends were prepared with various concentrations of triethyl citrate and thermoplastic sago starch in order to obtain a plastic material with a range of different mechanical properties that are suitable for packaging applications.The blends were melted by using twin-screw extruder.The samples obtained were examined for the effect of TC and TSS addition on thermal transitions and mechanical properties.The blends were characterized by Differential scanning calorimetry (DSC) for thermal transitions and by Instron testing machine for tensile strength, young modulus, elongation, and toughness.The addition of a plasticizer TC to a polymer PLA decreased the tensile strength and young modulus while increased the elongation at break and toughness. The addition of TC also shifted the glass transition temperature (Tg) down to lower temperatures and no crystallization of PLA was observed.The behavior of the PLA/TSS blends did not follow the same trend in all the compositions.Tensile strength and modulus decreased for PLA/TSS blends with 10% and 30% of TSS when compared to pure PLA, the elongation at break decreased insignificantly and no improvement in toughness was observed. On the other hand,PLA/TSS blend with 20% TSS had the highest tensile strength and elongation,but lowest modulus compared to pure PLA and other blends. A clear single Tg was observed for each of the PLA/TSS blends indicating high level of miscibility in each blend and the value of Tg decreased with the addition of TSS, with unstable trend.The PPLA/TSS blends varied in their mechanical properties and no obvious trend was observed when investigating the effect of TC or addition of TSS on the mechanical properties.This might be attributed to: first the nature of specimens, in which non homogenousity was observed obviously and second the anti plasticizing effect that appears in some of the PPLA/TSS blends containing 10% and 30% TSS due to additionof insufficient amounts of Plasticize

Promoting EFL learning towards peaceful global citizenship

This paper addresses SDG target 4.7 through the lens of Nancy Fraser’s (2008) conceptualisation of parity-of-participation. Her three-pillar conceptualisation includes the equitable distribution of material wealth, egalitarian status among all people, and equal access to representation. This paper attempts to apply her three pillars of participation to the primary classroom which has rarely been attempted before and never in the context of a middle income country. Drawing on interviews, surveys and drawingswith nearly 400 primary-school children in Egypt, we explore how they perceive participation within their classrooms and how participation may influence learning and future life. We conclude by noting that there is an irony in some children’s responses, whereby they display a strong ambition to speak English well, yet believe that they will learn to speak by being passive and silent in the classroom. Other children, however, critique the status quo and suggest more participatory approaches to learning English that will both improve their English mastery and model parity-of-participation in ways that may support their development into adults who strive to live peacefully together as global citizens

Children critique learning the "pure" subject of English in the traditional classroom

This paper makes a sociological exploration of the enforcement of strong boundaries between “pure” (disciplinary) and “applied” (common-sense) knowledge in primary school English classrooms. This article is innovative in its focus on how pupils describe and evaluate their own experiences. It addressed the research question: How do primary pupils experience the traditional classroom and what suggestions do they and their teachers express for making improvements to English language learning? We used observations in 18 classrooms, a written sentence-starter activity with 394 pupils and extended individual interviews with 38 pupils in Egyptian Government primary schools. The research took place in the 2015–2016 school years in response to the British Council’s ELT research awards funding (ELTRA). This article conveys the pupils’ experiences of learning the “pure” English; and also of experiencing another English outside the classroom, which was legitimised through speaking and interacting rather than through assessed writing. This paper suggests implications for the countries in the Middle East, and further afield, whose public primary schools still emphasise rote learning of the written word more than speaking English for communicative purposes

‘The teacher who helps children learn best’: affect and authority in the traditional primary classroom

This paper draws on the views of nearly 400 Year 5 pupils across nine classes in three government primary schools in Alexandria, Egypt. It explores how they perceived the role of affect in their classroom; and their teachers’ authority. By presenting pupils with sentences to complete, our research explored how the prevailing traditional approach to teaching influenced pupils in their English classroom. We also collected data by interviewing 38 pupils individually and carrying out Group Interviews with the pupils’ teachers. We concluded that pupils were acutely aware of how their feelings and their relationship to the teacher influenced their capacity to learn cognitively. Many of them said that they did not respect those teachers who refused to exercise an ethic of care in the classroom. In these cases, they did not see their teachers as authoritative; and pupils’ learning was impeded

Recent Outbreaks of Rift Valley Fever in East Africa and the Middle East

Rift Valley fever (RVF) is an important neglected, emerging, mosquito-borne disease with severe negative impact on human and animal health. Mosquitoes in the Aedes genus have been considered as the reservoir, as well as vectors, since their transovarially infected eggs withstand desiccation and larvae hatch when in contact with water. However, different mosquito species serve as epizootic/epidemic vectors of RVF, creating a complex epidemiologic pattern in East Africa. The recent RVF outbreaks in Somalia (2006–2007), Kenya (2006–2007), Tanzania (2007), and Sudan (2007–2008) showed extension to districts, which were not involved before. These outbreaks also demonstrated the changing epidemiology of the disease from being originally associated with livestock, to a seemingly highly virulent form infecting humans and causing considerably high-fatality rates. The amount of rainfall is considered to be the main factor initiating RVF outbreaks. The interaction between rainfall and local environment, i.e., type of soil, livestock, and human determine the space-time clustering of RVF outbreaks. Contact with animals or their products was the most dominant risk factor to transfer the infection to humans. Uncontrolled movement of livestock during an outbreak is responsible for introducing RVF to new areas. For example, the virus that caused the Saudi Arabia outbreak in 2000 was found to be the same strain that caused the 1997–98 outbreaks in East Africa. A strategy that involves active surveillance with effective case management and diagnosis for humans and identifying target areas for animal vaccination, restriction on animal movements outside the affected areas, identifying breeding sites, and targeted intensive mosquito control programs has been shown to succeed in limiting the effect of RVF outbreak and curb the spread of the disease from the onset

Towards Conservation of Omani Local Chicken: Phenotypic Characteristics, Management Practices and Performance Traits

Characterizing local chicken types and their mostly rural production systems is prerequisite for designing and implementing development and conservation programs. This study evaluated the management practices of small-scale chicken keepers and the phenotypic and production traits of their chickens in Oman, where conservation programs for local livestock breeds have currently started. Free-range scavenging was the dominant production system, and logistic regression analysis showed that socio-economic factors such as training in poultry keeping, household income, income from farming and gender of chicken owners influenced feeding, housing, and health care practices (p<0.05). A large variation in plumage and shank colors, comb types and other phenotypic traits within and between Omani chicken populations were observed. Male and female body weight differed (p<0.05), being 1.3±0.65 kg and 1.1±0.86 kg respectively. Flock size averaged 22±7.7 birds per household with 4.8 hens per cock. Clutch size was 12.3±2.85 and annual production 64.5±2.85 eggs per hen. Egg hatchability averaged 88±6.0% and annual chicken mortality across all age and sex categories was 16±1.4%. The strong involvement of women in chicken keeping makes them key stakeholders in future development and conservation programs, but the latter should be preceded by a comprehensive study of the genetic diversity of the Omani chicken populations

Detection and characterization of carbapenem resistant Gram-negative bacilli isolates recovered from hospitalized patients at Soba University Hospital, Sudan

BACKGROUND: Antimicrobial resistance (AMR) poses a complex threat to global health security and universal health coverage. Recently, nosocomial infections with carbapenemase-producing Gram-negative bacilli (GNB) is increasing worldwide. We report the molecular characterization and detection of genes associated with carbapenemase producing Gram negative bacteria isolated from hospitalized patients at Soba University Hospital (SUH) in Khartoum State, Sudan. RESULTS: Between October 2016 and February 2017, a total of 206 GNB clinical specimens were collected from hospitalized patients in SUH. Of 206 carbapenem resistance isolates, 171 (83 %) were confirmed as phenotypically resistant and 121 (58.7 %) isolates harboured one or more carbapenemase genes. New Delhi metallo-β-lactamase (NDM) types were the most predominant genes, blaNDM 107(52 %), followed by blaIMP 7 (3.4 %), blaOXA-48 5(2.4 %) and blaVIM 2 (0.9 %). Co-resistance genes with NDM producing GNB were detected in 87 (81.3 %) of all blaNDM producing isolates. NDM-1 was the most frequent subtype observed in 75 (70 %) blaNDM producing isolates. The highest percentage of resistance was recorded in ampicillin (98 %), cephalexin (93.5 %) amoxicillin clavulanic acid (90 %), cefotaxime (89.7 %), ceftriaxone (88.4 %), ceftazidime (84.2 %), sulfamethoxazole-trimethoprim (78.4 %) and nitrofurantoin (75.2 %), aztreonam (66 %) and temocillin (64 %). A close correlation between phenotypic and carbapenemase genes detection in all GNB was observed. CONCLUSIONS: The frequency of carbapenemase producing bacilli was found to be high in SUH. NDM was found to be the most prevalent carbapenemase gene among clinical isolates. Close surveillance across all hospitals in Sudan is required. The relative distribution of carbapenemase genes among GNB in nosocomial infections in Africa needs to be defined

Relevance of B-Lines on Lung Ultrasound in Volume Overload and Pulmonary Congestion: Clinical Correlations and Outcomes in Patients on Hemodialysis.

BACKGROUND: Volume overload in patients on hemodialysis (HD) is an independent risk factor for cardiovascular mortality. B-lines detected on lung ultrasound (BLUS) assess extravascular lung water. This raises interest in its utility for assessing volume status and cardiovascular outcomes. METHODS: End-stage renal disease patients on HD at the Island Rehab Center being older than 18 years were screened. Patients achieving their dry weight (DW) had a lung ultrasound in a supine position. Scores were classified as mild (0-14), moderate (15-30), and severe (\u3e30) for pulmonary congestion. Patients with more than 60 were further classified as very severe. Patients were followed for cardiac events and death. RESULTS: 81 patients were recruited. 58 were males, with a mean age of 59.7 years. 44 had New York Heart Association (NYHA) class 1, 24 had class 2, and 13 had class 3. In univariate analysis, NYHA class was associated with B-line classes ( CONCLUSION: At DW, BLUS is an independent risk factor for death and cardiovascular events in patients on HD

Eosinophils downregulate lung alloimmunity by decreasing TCR signal transduction

Despite the accepted notion that granulocytes play a universally destructive role in organ and tissue grafts, it has been recently described that eosinophils can facilitate immunosuppression-mediated acceptance of murine lung allografts. The mechanism of eosinophil-mediated tolerance, or their role in regulating alloimmune responses in the absence of immunosuppression, remains unknown. Using lung transplants in a fully MHC-mismatched BALB/c (H2d) to C57BL/6 (H2b) strain combination, we demonstrate that eosinophils downregulate T cell-mediated immune responses and play a tolerogenic role even in the absence of immunosuppression. We further show that such downregulation depends on PD-L1/PD-1-mediated synapse formation between eosinophils and T cells. We also demonstrate that eosinophils suppress T lymphocyte responses through the inhibition of T cell receptor/CD3 (TCR/CD3) subunit association and signal transduction in an inducible NOS-dependent manner. Increasing local eosinophil concentration, through administration of intratracheal eotaxin and IL-5, can ameliorate alloimmune responses in the lung allograft. Thus, our data indicate that eosinophil mobilization may be utilized as a novel means of lung allograft-specific immunosuppression