Interface behaviour and electrical performance of ruthenium Schottky contact on 4H-SiC after argon annealing

Rutherford backscattering spectrometry(RBS) analysis , carried out at various annealing temperatures, of a thin film of ruthenium on n-type 4-hexagonal silicon carbide (4H-SiC) showed evidence of ruthenium oxidation, ruthenium silicide formation and diffusion of ruthenium into silicon carbide starting from an annealing temperature of 400oC. Ruthenium oxidation was more pronounced, and ruthenium and Silicon inter-diffusion was very deep after annealing at 800oC. Raman analysis of some samples also showed ruthenium silicide formation and oxidation. The Schottky barrier diodes showed very good linear capacitance-voltage characteristics and excellent forward current-voltage characteristics, despite the occurrence of the chemical reactions and inter-diffusion of ruthenium and silicon at ruthenium-silicon-carbide interface, up to an annealing temperature of 800oC.http://link.springer.com/journal/12034hb201

Determination of kanamycin plasma levels using LC-MS and its pharmacokinetics in patients with multidrug-resistant tuberculosis with and without HIV-infection

The objectives of the study were: (1) to determine kanamycin plasma concentrations using liquid chromatography coupled with mass spectrometry (LC-MS), (2) to investigate kanamycin pharmacokinetics (PK) in patients with multi-drug resistant tuberculosis (MDR-TB), (3) to find out whether HIV infection, kidney dysfunction and antiretroviral drugs influence kanamycin PK. The study was designed as a non-randomized study involving male and female HIV- positive and HIVnegative patients admitted for MDR-TB treatment. Blood samples were collected before (baseline) and ½, 1, 2, 4, 8 and 24 hours after intramuscular injection of kanamycin. LC-MS was used to quantify kanamycin plasma concentrations. Thirty one patients including 13 HIV (+) participated in the study. The lower limit of detection and lower limit of quantification of kanamycin were 0.06 μg/ml and 0.15 μg/ml respectively. Kanamycin PK parameters were described and there was no significant difference between HIV-positive and HIV-negative patients. A statistical significant difference (p=0.0126) was found in the renal function in HIV - positive and HIV - negative patients. However, this difference did not affect kanamycin elimination. No interactions have been identified between antiretroviral drugs and kanamycin. Conclusion: LC-MS analysis method is highly specific and highly sensitive in the detection and quantification of kanamycin plasma concentrations. Kanamycin PK in patients with MDR-TB was described. Due to a limited number of patients, we cannot rule out any influence of HIV - infection, renal impairment and antiretroviral drugs on kanamycin pharmacokinetics. The relationship between the area under the curve of kanamycin free plasma concentrations (fAUC) and its minimum inhibitory concentrations (MIC) on M.tuberculosis isolated from the sputum of each patient should be assessed. Therefore, kanamycin free plasma concentrations and MIC should be determined.Web of Scienc

Alcohol, Hospital Discharge, and Socioeconomic Risk Factors for Default from Multidrug Resistant Tuberculosis Treatment in Rural South Africa: A Retrospective Cohort Study

Background: Default from multidrug-resistant tuberculosis (MDR-TB) treatment remains a major barrier to cure and epidemic control. We sought to identify patient risk factors for default from MDR-TB treatment and high-risk time periods for default in relation to hospitalization and transition to outpatient care. Methods: We retrospectively analyzed a cohort of 225 patients who initiated MDR-TB treatment between 2007 through 2010 at a rural TB hospital in the Western Cape Province, South Africa. Results: Fifty percent of patients were cured or completed treatment, 27% defaulted, 14% died, 4% failed treatment, and 5% transferred out. Recent alcohol use was common (63% of patients). In multivariable proportional hazards regression, older age (hazard ratio [HR]= 0.97 [95% confidence interval 0.94-0.99] per year of greater age), formal housing (HR=0.38 [0.19-0.78]), and steady employment (HR=0.41 [0.19-0.90]) were associated with decreased risk of default, while recent alcohol use (HR=2.1 [1.1-4.0]), recent drug use (HR=2.0 [1.0-3.6]), and Coloured (mixed ancestry) ethnicity (HR=2.3 [1.1-5.0]) were associated with increased risk of default (P<0.05). Defaults occurred throughout the first 18 months of the two-year treatment course but were especially frequent among alcohol users after discharge from the initial four-to-five-month in-hospital phase of treatment, with the highest default rates occurring among alcohol users within two months of discharge. Default rates during the first two months after discharge were also elevated for patients who received care from mobile clinics. Conclusions: Among patients who were not cured or did not complete MDR-TB treatment, the majority defaulted from treatment. Younger, economically-unstable patients and alcohol and drug users were particularly at risk. For alcohol users as well as mobile-clinic patients, the early outpatient treatment phase is a high-risk period for default that could be targeted in efforts to increase treatment completion rates

Solid state reaction and operational stability of ruthenium Schottky contact-on-6H-SiC under argon annealing

Thin films of ruthenium-on-6-hexagonal silicon carbide (6H-SiC) were analysed by Rutherford backscattering spectroscopy (RBS) at various annealing temperatures. Some thin film samples were also analysed by scanning electron microscope (SEM). RBS analysis indicated minimal element diffusion, and formation of ruthenium oxide after annealing at 500 oC. Large scale diffusion of ruthenium (Ru) was observed to commence at 700 oC. The SEM images indicated that the as-deposited Ru was disorderly and amorphous. Annealing of the thin film improved the grain quality of Ru. The fabricated Ru-6H-SiC Schottky barrier diodes (SBD) with nickel ohmic contacts showed excellent rectifying behaviour and linear capacitance-voltage characteristics up to an annealing temperature of 900 oC. The SBDs degraded after annealing at 1000 oC. The degradation of the SBDs is attributed to the inter-diffusion of Ru and Si at the Schottky-substrate interface.http://link.springer.com/journal/116642016-10-31hb201

Issues management : a strategy to manage pro-active change in South African universities

D.Comm.South African universities (SAUs) will be facing two main challenges in the next decade, namely: continuous change and decreasing predictability of the future. The urgency for change in SAUs flows mainly from conditions of turmoil and pressure, which in turn, emanate from public issues as they emerge within the macro-environment of SAUs. Decreasing predictability stems to a great extent from a lack of foreknowledge of how such emerging macro-environmental public issues will develop, and how they can influence SAUs through the public policy process. Management of SAUs therefore need to rely on crucial intelligence and foreknowledge concerning events, trends and developments of public issues that affect the future strategic viability of their institutions. They also need to rely on an agenda for understanding change as well as a means of marshalling participation in the public policy process, in order to manage public issues impacting on their institutions in a pro-active manner. At the onset four management concepts and processes were emphasised in this study, namely the concept of issues management within a macro-environmental context, issues management from an offensive environmental management perspective, strategy from an issues management perspective, and the concept of strategic change management within an issues management context. A proposed public issues management structure indicating the flow of information and actions within and outside the organisation, and how they could combine in public issues management programmes was also proposed. A macro-environmental perspective of universities in general and SAUs in particular was furthermore presented. It included the nature and function of universities, the history and management of SAUs and public issues impacting on SAUs. The practical aspect of this study was firstly based on an analysis of the different mission statements and mission goals of SAUs. The analysis was done to determine the management mode of management in SAUs; that is, whether management in SAUs operates in a pro-active management mode with regard to public issues in the public policy process. Secondly, models developed by Human & Horwitz (1992) as well as Ashley & Morrison (1995) and Theron (1994) were used to empirically determine the manner in which SAUs cope with change and to analyze the quality of the management of public issues in SAUs respectively. Descriptive data indicated that management in SAUs exhibit a proactive management mode with regard to public issues and a reasonable ability to cope with macro-environmental change. The management of emerging public issues and consequently pro-active change is, however, approached with bland commitment, a lack of strategic orientation and inadequate facilities and skills. It was concluded that, in view of the need in SAUs for a structured means of managing emerging public issues and consequently pro-active change, and in view of issues management constituting such a process, there is relevance for the implementation of issues management programmes in SAUs. In this regard a number of general recommendations were made with respect to managing the dynamic aspects of change, the implementation of strategies, and the implementation of an issues management strategy in SAUs. A framework was furthermore suggested for the implementation of an issues management strategy in SAUs in the belief that this framework, and the overall research reported in this thesis could be of theoretical as well as empirical value for managers in SAU

The management of issues in community pharmacies

M.Com. (Business Management)Please refer to full text to view abstrac

Do HIV infection and antiretroviral therapy influence multidrug-resistant tuberculosis treatment outcomes?

The aim of this study was to find out whether human immunodeficiency virus (HIV)-infection and antiretroviral drugs influence multidrug-resistant (MDR)-tuberculosis (TB) treatment outcomes. The study compares MDR-TB treatment outcomes between HIV-positive and HIV-negative patients. It involved patients admitted for treatment of MDR-TB between 1 January 2004 and 31 December 2006. From 363 patients selected, 268 (177 males and 91 females) had MDR-TB and 95 patients (59 males and 36 females) were co-infected with HIV. Children in the HIV-negative group were 41 and 7 in the HIV-positive group. The HIV-infection was treated with Stavudine, Lamivudine and Efavirenz in 54 patients. Kanamycin, Ethionamide, Ofloxacin, Terizidone, Pyrazinamide and Ethambutol were used for MDR-TB treatment. In HIV-negative and HIV-positive patients MDR-TB treatment outcomes were, respectively as follows: 37 and 35% cure, 9 and 5% treatment failure, 20 and 25% lost to follow up, 11 and 17% mortality, 19 and 13% treatment completed, 6 and 5% transfer-out. The cure rate was 100% in children. In HIV-positive patients, MDR-TB cure rate was 35% in patients on ARVs and 34% in patients not receiving ARVs. The difference between these cure rates is not statistically significant (p-value = 0.79). The median (range) duration of ART before the start of MDR-TB treatment was 10.5 (1 to 60) months and did not influence MDR-TB treatment outcomes. In children, the full treatment was supervised in hospital. This could explain the 100% cure rate. Adults’ treatment was supervised in hospital only during the intensive phase then followed up as out patients over 18 months. According to the results of this study, HIV-infection and antiretroviral therapy did not influence MDR-TB treatment outcomes.Web of Scienc

Microstructure evolution and diffusion of ruthenium in silicon carbide, and the implications for structural integrity of SiC layer in TRISO coated fuel particles

A thin film of ruthenium (Ru) was deposited on n-type 4H-SiC and 6H-SiC by electron beam deposition technique so as to study interface reaction of ruthenium with silicon carbide at various annealing temperatures, and in two annealing environments namely vacuum and air. The Ru-4H-SiC and Ru-6H-SiC films were both annealed isochronally in a vacuum furnace at temperatures ranging from 500 to 1000 C, and the second set of samples were also annealed in air for temperatures ranging from 100 C to 600 C. After each annealing temperature, the films were analysed by Rutherford Backscattering spectrometry (RBS). Raman analysis and X-ray diffraction analysis were also used to analyse some of the samples. RBS analysis of 4H-SiC annealed in a vacuum showed evidence of formation of ruthenium silicide (Ru2Si3) and diffusion of Ru into SiC starting from annealing temperature of 700 C going upwards. In the case of Ru-6H-SiC annealed in a vacuum, RBS analysis showed formation of Ru 2Si3 at 600 C, in addition to the diffusion of Ru into SiC at 800 C. Raman analysis of the Ru-4H-SiC and Ru-6H-SiC samples that were annealed in a vacuum at 1000 C showed clear D and G carbon peaks which was evidence of formation of graphite. As for the samples annealed in air ruthenium oxidation started at a temperature of 400 C and diffusion of Ru into SiC commenced at temperatures of 500 C for both Ru-4H-SiC and Ru-6H-SiC. X-ray diffraction analysis of samples annealed in air at 600 C showed evidence of formation of ruthenium silicide in both 4H and 6H-SiC but this was not corroborated by RBS analysis

Solid state reaction of ruthenium with silicon carbide, and the implications for its use as a Schottky contact for high temperature operating Schottky diodes

A thin film of ruthenium was deposited on n-type-4-hexagonal-silicon- carbide (4H-SiC) so as to studythe interface behaviour of the ruthenium Schottky contact with silicon carbide. Ruthenium (Ru) Schottkydiode dots were also fabricated by deposition of ruthenium on n-type-4H-SiC which had nickel as aback ohmic contact. The Ru-4H-SiC Schottky barrier diodes (SBDs) and thin films were both annealedisochronally in a vacuum furnace at various temperatures. Rutherford-backscattering-spectrometry anal-ysis of the thin film sample showed evidence of formation of ruthenium silicide (Ru2Si3) and diffusionof ruthenium into silicon carbide at annealing temperatures of 700?C and 600?C respectively. Ramananalysis of the sample that was annealed in a vacuum at 1000?C showed evidence of the formation ofgraphite, and Ru2Si3. Despite the occurrence of the chemical reactions and diffusion of ruthenium into4H-SiC, the SBDs were operationally stable up to the final annealing temperature of 1000?C