COVID-19 and the academe in South Africa: Not business as usual

The famous R.E.M. song laments ‘It’s the end of the world as we know it, I had some time alone, I feel fine…’. Many South Africans would agree that COVID-19 signals the end of the world (or business) as we know it, and through the lockdown we have certainly had some time alone. But contrary to the lyrics, all may not be fine, especially for South Africa’s scientific community. The novel coronavirus SARS-CoV-2 has impacted every economic and social sector1 across the globe, including higher education in South Africa. Every student and staff member at a higher education institution will have been affected in some way and to varying degrees; not one person will emerge from this unscathed. It is impossible to predict every short- and long-term impact of the COVID-19 pandemic, but we will experience the aftershocks for a long time to come. Here we discuss some of these impacts, ranging from undergraduate level to large research projects, and we offer suggestions on how to mitigate some of the damage.Geograph

Treatment of TRISO-coated particles with CF4 in a low temperature plasma

An alternative recovery method to the mechanical crushing of off-specification tri-structural-isotropic (TRISO) coated fuel microspheres is demonstrated. It is shown that the inert SiC layer can be completely removed by etching with the active fluorine species from an inductively coupled radio-frequency CF4 glow-discharge impinging a static bed from the top, at a working pressure of 1 kPa. At this pressure mass transport does not have a rate limiting role and the chemical reaction itself is rate determining. A treatment time of roughly 4 h is required for the conditions reported hereThe South African National Research Foundationhttp://www.elsevier.com/locate/jnucmatai201

Daily interruption of sedation in critically ill children: Study protocol for a randomized controlled trial

Background: In adult patients who are critically ill and mechanically ventilated, daily interruption of sedation (DSI) is an effective method of improving sedation management, resulting in a decrease of the duration of mechanical ventilation, the length of stay in the intensive care unit (ICU) and the length of stay in the hospital. It is a safe and effective approach and is common practice in adult ICUs. For critically ill children it is unknown if DSI is effective and feasible. The aim of this multicenter randomized controlled trial is to evaluate the safety and

Thermal annealing behaviour of Pd Schottky contacts on melt-grown single crystal ZnO studied by IV and CV measurements

Current–voltage (IV) and capacitance–voltage (CV) measurement techniques have successfully been employed to study the effects of annealing highly rectifying Pd/ZnO Schottky contacts. IV results reveal a decrease in the contact quality with increasing annealing temperature as confirmed by a decrease in the zero bias barrier height and an increase in the reverse current measured at −1.5 V. An average barrier height of (0.77 ± 0.02) eV has been calculated by assuming pure thermionic emission for the as-deposited material and as (0.56 ± 0.03) eV after annealing at 550 ◦C. The reverse current has been measured as (2.10 ± 0.01) × 10−10 A for the as-deposited and increases by 5 orders of magnitude after annealing at 550 ◦C to (1.56 ± 0.01) × 10−5 A. The depletion layer width measured at −2.0 V has shown a strong dependence on thermal annealing as it decreases from 1.09 m after annealing at 200 ◦C to 0.24 m after annealing at 500 ◦C, resulting in the modification of the dopant concentration within the depletion region and hence the current flowing through the interface from pure thermionic emission to thermionic field emission with the donor concentrations increasing from 6.90 × 1015 cm−3 at 200 ◦C to 6.06 × 1016 cm−3 after annealing at 550 ◦C. This increase in the volume concentration has been explained as an effect of a conductive channel that shifts closer to the surface after sample annealing. The series resistance has been observed to decrease with increase in annealing temperature. The Pd contacts have shown high stability up to an annealing temperature of 250 ◦C as revealed by the IV and CV characteristics after which the quality of the contacts deteriorates with increase in annealing temperature.http://www.elsevier.com/locate/msebhb201

Exploring South Africa’s southern frontier: A 20-year vision for polar research through the South African National Antarctic Programme

Antarctica, the sub-Antarctic islands and surrounding Southern Ocean are regarded as one of the planet’s last remaining wildernesses, ‘insulated from threat by [their] remoteness and protection under the Antarctic Treaty System’1 . Antarctica encompasses some of the coldest, windiest and driest habitats on earth. Within the Southern Ocean, sub-Antarctic islands are found between the Sub-Antarctic Front to the north and the Polar Front to the south. Lying in a transition zone between warmer subtropical and cooler Antarctic waters, these islands are important sentinels from which to study climate change.2 A growing body of evidence3,4 now suggests that climatically driven changes in the latitudinal boundaries of these two fronts define the islands’ short- and long-term atmospheric and oceanic circulation patterns. Consequently, sub-Antarctic islands and their associated terrestrial and marine ecosystems offer ideal natural laboratories for studying ecosystem response to change.5 For example, a recent study6 indicates that the shift in the geographical position of the oceanic fronts has disrupted inshore marine ecosystems, with a possible impact on top predators. Importantly, biotic responses are variable as indicated by different population trends of these top predators.7,8 When studied collectively, these variations in species’ demographic patterns point to complex spatial and temporal changes within the broader sub-Antarctic ecosystem, and invite further examination of the interplay between extrinsic and intrinsic drivers

Occupational exposure to chemicals and fetal growth: the Generation R Study

Background Developmental diseases, such as birth defects, growth restriction and preterm delivery, account for >25 of infant mortality and morbidity. Several studies have shown that exposure to chemicals during pregnancy is associated with adverse birth outcomes. The aim of this study was to identify whether occupational exposure to various chemicals might adversely influence intrauterine growth patterns and placental weight.Methods Associations between mat

Pharmacokinetic aspects of retinal drug delivery

Drug delivery to the posterior eye segment is an important challenge in ophthalmology, because many diseases affect the retina and choroid leading to impaired vision or blindness. Currently, intravitreal injections are the method of choice to administer drugs to the retina, but this approach is applicable only in selected cases (e.g. anti-VEGF antibodies and soluble receptors). There are two basic approaches that can be adopted to improve retinal drug delivery: prolonged and/or retina targeted delivery of intravitreal drugs and use of other routes of drug administration, such as periocular, suprachoroidal, sub-retinal, systemic, or topical. Properties of the administration route, drug and delivery system determine the efficacy and safety of these approaches. Pharmacokinetic and pharmacodynamic factors determine the required dosing rates and doses that are needed for drug action. In addition, tolerability factors limit the use of many materials in ocular drug delivery. This review article provides a critical discussion of retinal drug delivery, particularly from the pharmacokinetic point of view. This article does not include an extensive review of drug delivery technologies, because they have already been reviewed several times recently. Instead, we aim to provide a systematic and quantitative view on the pharmacokinetic factors in drug delivery to the posterior eye segment. This review is based on the literature and unpublished data from the authors' laboratory.Peer reviewe

The inheritance of hair length in Karakul sheep with special reference to its relationship with skin thickness and hair thickness components

No Abstrac

Study on free-surface aeration with high-velocity air-water flows in open-channels

China’s biggest source of the renewable energy is hydropower, with a share of 85 %, in 2013, of the total renewable power generation. For the tenth sequential year, China has maintained the country’s leading role in global hydropower development by installing more hydropower plants than the rest of the world combined. There are some important issues when constructing hydropower plants and designing spillways and chute sidewalls. One of these issues is considered to be the presence of air, which can be entrained in large amounts through the free surface into the water within high-velocity flows and leads to the bulk of the flow to increase. This project aims to describe the relationship between free-surface entrapped deformation and air entrainment (entrained air in the flow) by studying uniform self-aerated flows in open-channels. The performed experiments have been carried out in a physical scaled model at the State key laboratory of Hydraulics and Mountain River Engineering at Sichuan University in Chengdu, China. A literature study has been done in order to examine the self-aerated flows in open-channels and used as the basis for the experiments in this project. The software, Free Video to JPG Converter, AUTOCAD, Photoshop, OriginPro and Motion Studio have been utilized for the evaluation of free-surface deformation curve and the process of surface deformation and air entrainment. After analysing images taken by a camera during the experiments, the result has been divided in two parts, namely, to describe the air-entrainment phenomenon using the relevant curve type and fitting the obtained curves into the known curves, and to obtain the critical radius of curvature for the air-entrainment affected by flow mean velocity and water depth. Based on the experimental data from the image analysis and one sample t-test which has been utilized to obtain a confidence interval of the adjusted R-square in order to evaluate how good fitting the relevant curves have, the Gaussian-curve type have been decided to describe the phenomenon. After the image analysis of the free-surface deformation curve type has been done, the process of surface deformation and air entrainment has been evaluated. For this evaluation, various processes with various durations have been observed. As a result, it is found that the surface achieves closure at a relatively low position at a range of 7 to 19 milliseconds and the free-surface deformation occurs when the air bubble is entrained into the flow, varies between 8 and 19,5 milliseconds for different observation. The results of evaluating the radius of curvature with respect to the time of occurrence indicate that the free-surface deformation intensity in the experiments exceeds the critical condition of curvature radius when the surface instability occurs. The results of the radius of curvature reveal that that the radius of curvature has a “bell-shape” behaviour. It is shown that the critical radius of curvature varies for different processes and it occurs after the maximum value is reached, the critical radius of curvature has a range between 0,53 and 2,97 mm for all the processes. The results show that the experiments have a good potential for evaluating the process of freesurface deformation and air entrainment. To make final conclusions, further studies and experiments in self-aerated open-channel flows should be done including non-intrusive measurements for the entrained air bubble size and the relationship between the free-surface deformation and bubble distributionsKinas största källa till förnybar energi är vattenkraft, med en andel på 85 %, år 2013, av den totala förnybara kraftproduktionen. Tio år i rad har Kina behållit landets ledande roll i den globala vattenkraftutvecklingen genom att installera fler vattenkraftverk än resten av världen kombinerat. Det finns några viktiga frågor vid konstruktionen av vattenkraftverk och utformningen av spillvägar och skuggade sidoväggar. Ett av dessa problem anses vara närvaro av luft, vilket kan medföras i stora mängder genom den fria ytan i vattnet inom höghastighetsflöden och leder till att huvuddelen av flödet ökar. Detta projekt syftar till att beskriva sambandet mellan infångad deformation och luftintagning (medbringad luft i flödet) genom att studera enhetliga, självluftade flöden i öppna kanaler. De utförda experimenten har utförts i en fysisk skalad modell vid Institutionen för Hydraulik och Bergflodteknik vid Sichuan Universitetet i Chengdu, Kina. En litteraturstudie har gjorts för att undersöka de själv-luftade flödena i öppna kanaler och använts som grund för experimenten i detta projekt. Programvaran, Free Video to JPG Converter, AUTOCAD, Photoshop, OriginPro och Motion Studio har använts för utvärdering av fri-deformationskurvan och processen för yta-deformation och luftintagning. Efter att ha analyserat bilderna som tagits av en kamera under experimenten har resultatet uppdelats i två delar, nämligen att beskriva luftintagningsfenomenet med den relevanta kurvtypen och anpassa de erhållna kurvorna till de kända kurvorna samt att erhålla den kritiska radien av krökning för luftintag som påverkas av flödesmedelhastighet och vattendjup. Baserat på experimentella data från bildanalysen och ett prov t-test som har utnyttjats för att erhålla ett konfidensintervall för den justerade R-kvadraten, vilket utvärderar de relevanta kurvorna passning, har Gauss-kurvtypen bestämts för att beskriva fenomenet. Efter att bildanalysen av deformationskurvan för fria-ytan har gjorts, har processen för yta-deformation och luftintagning utvärderats. För denna utvärdering har olika processer med olika varaktighet observerats. Som ett resultat är det konstaterat att ytan åstadkommer stängning vid ett förhållandevis lågt läge i intervallet 7 till 19 millisekunder och fri-yta deformationen uppträder när luftbubblan medföljer flödet varierar mellan 8 och 19,5 millisekunder för olika observationer. Resultaten av utvärdering av krökningsradie med avseende på tidpunkten för förekomsten indikerar att intensiteten för friyta deformationen i experimenten överstiger kretsens kritiska tillstånd när ytans instabilitet uppträder. Resultatet av krökningsradien visar att krökningsradien har ett "klockformat" beteende. Det visas att den kritiska krökningsradien varierar för olika processer och det inträffar efter att maximivärdet har uppnåtts, den kritiska krökningsradien har ett intervall mellan 0,53 och 2,97 mm för alla processer. Resultaten visar att experimenten har en bra potential för utvärdering av processen med fri-yta deformationen och luftintagningen. För att göra slutgiltiga slutsatser bör ytterligare studier och experiment i självluftade öppna kanalflöden göras, inklusive icke-påträngande mätningar för den medförde luftbubbelstorleken och förhållandet mellan deformation och bubbeldistributionen för fria-ytan.水电作为最主要的一种可再生能源利用形式，其在中国国内可再生能源利用总量中占 比达到 85%（2013 年），在近几十年中，中国作为世界范围内加强水电利用的主导国 家，引领着水利水电工程的建设。在水利水电工程建设过程中，面对高流速、大流量 条件下的水力运行，大型泄洪建筑物（如泄洪洞、溢洪道等）的泄水安全，直接关系 着整体水利水电工程的运行安全，其中一个重要的高速水力学问题为由于自由面卷吸 掺气引起的明渠高速掺气水流问题。 本项目旨在研究明渠水流自由面卷吸掺气过程形成机理进行研究，基于对自掺气水流 研究背景充分了解的基础上，在四川大学水力学与山区河流开发保护国家重点实验室 中采用明渠水槽进行自由面卷吸掺气观测试验研究，并采用高速摄像与图像分析技 术，整合利用多种分析软件，包括，Free Video to JPG Converter, AUTOCAD, Photoshop, OriginPro 和 Motion Studio 等，对自由面凹陷形态特征与卷吸掺气过程 进行分析。研究内容主要包括一下两部分：1）对明渠水流局部自由面水体凹陷形态进 行分析，确定描述自由面凹陷形态的曲线形式；2）对自由面凹陷卷吸掺气过程进行分 析，确定凹陷卷吸气泡过程中自由面形态变化规律及卷吸气泡的临界形态条件。 通过对试验观测的明渠水流局部自由面凹陷形态曲线采用拟合相关系数进行对比，并 进行定量分析以及 T-检验，表明自由面凹陷形态更符合高斯曲线形式，采用高斯曲线 顶点的曲率半径可以对自由面凹陷形态进行定量描述。在此基础上对自由面卷吸气泡 过程进行观测分析，结果表明，自由面闭合过程发生时间约为在观测到自由面凹陷起 7~19 ms，而对于不同观测情况，卷吸气泡过程所需时间约为 8~19,5 ms。通过对于自 由面凹陷变形并卷吸掺气过程的观测分析，验证了自由面凹陷卷吸掺气机理的理论分 析，即当自由面凹陷变形过程中当形态形变无法克服紊动作用时，超过临界条件时， 自由面发生凹陷失稳过程，并在此过程中由于凹陷两侧自由面闭合形成卷吸气泡。试 验观测的卷吸气泡过程中凹陷形态曲率半径随时间变化过程类似“钟形”，过程存在一 个临界峰值位置，在此之后曲率半径迅速减小，对于不同掺气过程，曲率半径峰值位 置变化范围约为 0,53 mm~2,97 mm。 本项目研究表明了采用试验对于明渠自由面形态演变及卷吸掺气机理的研究是可行 的，在今后进一步的研究过程中，应当发掘采用非接触式的试验测量方式对明渠水气 二相流进行直观的研究，并进一步研究自由面凹陷形态特征与卷吸气泡尺寸之间的定 量关系，全面揭示明渠高速水流自掺气形成机理

COVID-19 and the academe in South Africa : not business as usual

The novel coronavirus SARS-CoV-2 has impacted every economic and social sector1 across the globe, including higher education in South Africa. Every student and staff member at a higher education institution will have been affected in some way and to varying degrees; not one person will emerge from this unscathed. It is impossible to predict every short- and long-term impact of the COVID-19 pandemic, but we will experience the aftershocks for a long time to come. Here we discuss some of these impacts, ranging from undergraduate level to large research projects, and we offer suggestions on how to mitigate some of the damage.http://www.sajs.co.zahj2020Geography, Geoinformatics and MeteorologyPlant Production and Soil Scienc