Selective and sensitive toxic gas-sensing mechanism in a 2D Janus MoSSe monolayer.

With an inspiration of sensing toxic gases, this study is aimed at exploring the potential of a Janus MoSSe monolayer as a gas sensor. Here, we focused on the adsorption mechanism after the exposure to NH3, NO2, NO, HCN, CO2, CO, H2, H2S and SO2 on both the S and Se sites of MoSSe. We investigated the structural geometries and electronic, sensing and electron-transport properties before and after adsorption of the aforementioned gases by applying DFT calculations. The results revealed the higher binding strength of NO2/SO2 and NO on Se and S sites, respectively, among all the gas adsorptions on the MoSSe monolayer. Moreover, DOS revealed strong orbital contributions at EF, which confirmed the n/p-type semiconducting character for the NO/NO2 adsorbed MoSSe monolayer. Further, the specific work function alteration after the adsorption of NO2, SO2 and NO indicated that the MoSSe monolayer could be a potential candidate for Φ-type gas sensor at 300 K. Additionally, the higher electron transmission and prominent electrical response values of 76.4/56 µA and 82 µA suggested a maximum sensitivity of 98%/89% and 93% at a particular voltage for NO2/SO2 and NO on Se and S sites, respectively. Thus, our results promote surface selectivity, i.e. S or Se site, and better sensitivity with recycling potential could enable sensing application of the Janus MoSSe monolayer for toxic gases detection.

Metallic one-dimensional heterostructure for gas molecule sensing.

We have investigated a new metallic core-shell nanowire (NW) geometry of that could be obtained experimentally, that is silicon (Si) and germanium (Ge) NWs with cores constituted by group-10 elements palladium (Pd) and platinum (Pt). These NWs are optimized with two different diameters of 1.5 Å and 2.5 Å. The nanowires having diameter of 1.5 Å show semi-metallic nature with GGA-PBE calculation and metallic nature while spin orbit interaction (SOC) is included. The quantum conductance of the NWs increases with the diameter of the nanowire. We have investigated current-voltage (IV) characteristics for the considered NWs. It has been found that current values in accordance with applied voltage show strong dependence on the diameter of the NWs. The optical study of the NWs shows that absorption co-efficient peak moves to lower energies; due to quantum confinement effect. Furthermore, we have extensively studied optical response of Pd and Pt based core-shell NWs in O2 and CO2 environment. Our study on Si and Ge based metallic core/shell NW show a comprehensive picture as possible electron connector in future nano-electronic devices as well as nano gas detector for detecting O2 gas.

3D characterisation of dry powder inhaler formulations: Developing X-ray micro computed tomography approaches.

Carrier-based dry powder inhaler (DPI) formulations need to be accurately characterised for their particle size distributions, surface roughnesses, fines contents and flow properties. Understanding the micro-structure of the powder formulation is crucial, yet current characterisation methods give incomplete information. Commonly used techniques like laser diffraction (LD) and optical microscopy (OM) are limited due to the assumption of sphericity and can give variable results depending on particle orientation and dispersion. The aim of this work was to develop new three dimensional (3D) powder analytical techniques using X-ray computed tomography (XCT) that could be employed for non-destructive metrology of inhaled formulations. α-lactose monohydrate powders with different characteristics have been analysed, and their size and shape (sphericity/aspect ratio) distributions compared with results from LD and OM. The three techniques were shown to produce comparable size distributions, while the different shape distributions from XCT and OM highlight the difference between 2D and 3D imaging. The effect of micro-structure on flowability was also analysed through 3D measurements of void volume and tap density. This study has demonstrated for the first time that XCT provides an invaluable, non-destructive and analytical approach to obtain number- and volume-based particle size distributions of DPI formulations in 3D space, and for unique 3D characterisation of powder micro-structure.

Severe disease presentation and poor outcomes among pediatric systemic lupus erythematosus patients in South Africa.

Background Systemic lupus erythematosus (SLE) is a life-threatening multisystem autoimmune disease that is more severe in patients of African ancestry and children, yet pediatric SLE on the African continent has been understudied. This study describes a cohort of pediatric SLE (PULSE) patients in South Africa. Methods Patients with a diagnosis of SLE (1997 American College of Rheumatology criteria) diagnosed prior to age 19 years in Cape Town, South Africa, were enrolled in this cross-sectional study from September 2013 to December 2014. Information on clinical and serological characteristics was extracted from medical records. Results were compared to a well-described North American pediatric SLE cohort. Results Seventy-two South African patients were enrolled in the study; mean age 11.5 years; 82% were girls. The racial distribution was 68% Coloured, 24% Black, 5% White and 3% Asian/Indian. Most patients presented with severe lupus nephritis documented by renal biopsy (61%). Of patients with lupus nephritis, 63% presented with International Society of Nephrology/Renal Pathology Society class III or IV. Patients in the PULSE cohort were more likely to be treated with cyclophosphamide, methotrexate and azathioprine. The PULSE cohort had high disease activity at diagnosis (mean Systemic Lupus Erythematosus Disease Activity Index-2K (SLEDAI-2K) 20.6). The SLEDAI-2K at enrolment in the PULSE cohort (5.0) did not differ from the North American pediatric SLE cohort (4.8). Sixty-three per cent of the PULSE cohort had end organ damage with Systemic Lupus International Collaborating Clinics Damage Index (SLICC-DI) score >0 (mean SLICC-DI 1.9), compared to 23% in a previously reported US cohort. Within the PULSE cohort, nine (13%) developed end-stage renal disease with six (8%) requiring transplant, strikingly higher than North American peers (transplant rate <1%). Conclusions The PULSE cohort had highly active multiorgan disease at diagnosis and significant disease damage at enrolment in the South African registry. South African patients have severe lupus nephritis and poor renal outcomes compared to North American peers. Our study revealed a severe disease phenotype in the PULSE cohort resulting in poor outcomes in this high-risk population.

Liver transplantation at Red Cross War Memorial Children's Hospital.

UNLABELLED: The liver transplant programme for infants and children at Red Cross War Memorial Children's Hospital is the only established paediatric service in sub-Saharan Africa. Referrals for liver transplant assessment come from most provinces within South Africa as well as neighbouring countries. PATIENTS AND METHODS: Since 1987, 81 children (range 6 months-14 years) have had 84 liver transplants with biliary atresia being the most frequent diagnosis. The indications for transplantation include biliary atresia (48), metabolic (7), fulminant hepatic failure (10), redo transplants (3) and other (16). Four combined liver/kidney transplants have been performed. Fifty-three were reduced-size transplants with donor/recipient weight ratios ranging from 2:1 to 11:1 and 32 children weighed less than 10 kg. RESULTS: Sixty patients (74%) survived 3 months-14 years post-transplant. Overall cumulative 1- and 5-year patient survival figures are 79% and 70% respectively. However, with the introduction of prophylactic intravenous ganciclovir and the exclusion of hepatitis B virus (HBV) IgG core Ab-positive donors, the 1-year patient survival is 90% and the projected 5-year paediatric survival is > 80%. Early (< 1 month) post-liver-transplant mortality was low. Causes include primary malfunction (1), inferior vena cava thrombosis (1), bleeding oesophageal ulcer (1), sepsis (1) and cerebral oedema (1). Late morbidity and mortality was mainly due to infections: de novo hepatitis B (5 patients, 2 deaths), Epstein-Barr virus (EBV)- related post-transplantation lymphoproliferative disease (12 patients, 7 deaths) and cytomegalovirus (CMV) disease (10 patients, 5 deaths). Tuberculosis (TB) treatment in 3 patients was complicated by chronic rejection (1) and TB-drug-induced subfulminant liver failure (1). CONCLUSION: Despite limited resources, a successful paediatric programme has been established with good patient and graft survival figures and excellent quality of life. Shortage of donors because of infection with HBV and human immunodeficiency virus (HIV) leads to significant waiting-list mortality and infrequent transplantation.

Infantile jejunal mucosa in infection and malnutrition.

Sixteen children with refractory diarrhea and three malnourished children who had frequent episodes of acute gastroenteritis but little diarrhea at the time of hospital admission, were studied by peroral upper small intestinal biopsy. Six children were adequately nourished; five children weighed 62 to 79% of expected weight and eight weighed less than 60% of expected weight. Two of the malnourished children had giardiasis. Pathogenic bacteria were found in only one case. Varying degrees of mucosal atrophy with reduction of mean villous height were seen in 18 cases. The concentration of mononuclear inflammatory cells and plasma cells was about half that seen in well-nourished children with severe nongastrointestinal infections. The concentration of mononuclear cells in the lamina propria was about twice that seen in normal adults. The proportions of IgA-producing cells and cells that stained for secretory component were significantly reduced, as compared with normal adult control values. This reduction was most striking in children with malnutrition complicated by giardiasis. Enzyme histochemical studies were performed for leucine aminopeptidase, alkaline phosphatase and acid phosphatase. There was a tendency for considerably reduced acid phosphatase activity in all clinical groups (kwashiorkor, marasmic kwashiorkor and marasmus) of growth-retarded infants.

Renal echinococcosis in children. A report of 2 cases.

Two cases of renal echinococcosis in children are described. In one of the children the lungs and liver were involved as well. The pathology, diagnosis and treatment, as well as the usefulness and limitations of the Casoni skin test and serological tests, are discussed.