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Nadeem Kassam,1 Philip B Adebayo,1 Iris Martin Matei,1 Eric Aghan,2 Samina Somji,1 Samwel Paul Kadelya,1 Yasson Abha,1 Frank Elton Swai,2 Mangaro Mabusi,1 Kamran Hameed,1 Hanifa Mbithe,1 Alyyah Thawer,1 Mandela Charles Makakala,1 Fatma Amirali Bakshi,1 Harrison Chuwa,1 Masolwa Ng’wanasayi,1 Casmir M Wambura,1 Robert Sostenes Mvungi,1 James Orwa,3 Munish Sharma,4 George Udeani,5 Salim Surani5 1Department of Internal Medicine, Aga Khan Health Service, Dar-es-Salaam, Tanzania; 2Department of Family Medicine, Aga Khan University Medical College, Nairobi, Kenya; 3Department of Population Health, Aga Khan University Medical College, Nairobi, Kenya; 4Department of Medicine, Division of Pulmonology and Critical Care, Baylor Scott and White Medical Center, Temple, Texas, USA; 5Department of Pharmacy, A&M University, College Station, Texas, USACorrespondence: Nadeem Kassam, Department of Internal Medicine, Aga Khan Health Service, Dar-es-Salaam, Tanzania, Email Kassamnadeem2@gmail.comIntroduction: Despite the implementation of complex interventions, ICU mortality remains high and more so in developing countries. The demand for critical care in Sub-Saharan Africa is more than ever before as the region experiences a double burden of rising rates of non-communicable diseases (NCD) in the background battle of combating infectious diseases. Limited studies in Tanzania have reported varying factors associated with markedly high rates of ICU mortality. Investigating the burden of ICU care remains crucial in providing insights into the effectiveness and challenges of critical care delivery.Material and Methods: A single-center retrospective study that reviewed records of all medically admitted patients admitted to the ICU of the Aga Khan Hospital, Dar-es-Salaam, from 1st October 2018 to 30th April 2023. To define the population in the study, we used descriptive statistics. Patients’ outcomes were categorized based on ICU survival. Binary logistic regression was run (at 95% CI and p-value

Nadeem Kassam,1 Salim Surani,2 Kamran Hameed,3 Eric Aghan,4 Robert Mayenga,1 Iris Matei,1 Gijsberta Jengo,1 Fatma Bakshi,3 Hanifa Mbithe,3 James Orwa,5 George Udeani,2 Samina Somji3 1Department of Internal Medicine, Aga Khan Hospital, Mwanza, Tanzania; 2Department of Pharmacy, A&M University, College Station, TX, USA; 3Department of Internal Medicine, Aga Khan Hospital, Dar es Salaam, Tanzania; 4Department of Family Medicine Aga Khan University Medical College, Dar es Salaam, Tanzania; 5Department of Population Health, Aga Khan University, Nairobi, KenyaCorrespondence: Nadeem Kassam, Email Kassamnadeem2@gmail.comIntroduction: Atherosclerotic Cardiovascular Disease (ASCVD) is the leading cause of death worldwide. In Diabetics, ASCVD is associated with poor prognosis and a higher case fatality rate compared with the general population. Sub-Saharan Africa is facing an epidemiological transition with ASCVD being prevalent among young adults. To date, over 20 million people have been living with DM in Africa, Tanzania being one of the five countries in the continent reported to have a higher prevalence. This study aimed to identify an individual’s 10-year ASCVD absolute risk among a diabetic cohort in Tanzania and define contextual risk enhancing factors.Methods: A prospective observational study was conducted at the Aga Khan hospital, Mwanza, for a period of 8 months. The hospital is a 42-bed district-level hospital in Tanzania. Individuals 10-year risk was calculated based on the ASCVD 2013 risk calculator by ACC/AHA. Pearson’s chi-square or Fischer’s exact test was used to compare categorical and continuous variables. Multivariable analysis was applied to determine contextual factors for those who had a high 10-year risk of developing ASCVD.Results: The overall cohort included 573 patients. Majority of the individuals were found to be hypertensive (n = 371, 64.7%) and obese (n = 331, 58%) having a high 10-year absolute risk (n = 343, 60%) of suffering ASCVD. The study identified duration of Diabetes Mellitus (> 10 years) (OR 8.15, 95% CI 5.25– 14.42), concomitant hypertension (OR 1.82 95% CI 1.06– 3.06), Diabetic Dyslipidemia (OR 1.44, 95% CI 1.08– 1.92) and deranged serum creatinine (OR 1.03, 95% CI 1.02– 1.03) to be the risk enhancing factors amongst our population.Conclusion: The study confirms the majority of diabetic individuals in the lake region of Tanzania to have a high 10-year ASCVD risk. The high prevalence of obesity, hypertension and dyslipidemia augments ASCVD risk but provides interventional targets for health-care workers to decrease these alarming projections.Keywords: diabetes mellitus, Tanzania, factors, cardiovascular risk, primary prevention, ASCVD

Nadeem Kassam,1 Eric Aghan,2 Omar Aziz,1 Hanifa Mbithe,1 Kamran Hameed,1 Reena Shah,3 Salim Surani,4 James Orwa,5 Samina Somji1 1Internal Medicine, The Aga Khan Hospital, Dar es Salaam, Tanzania & Aga Khan University, Medical College, Dar-es- Salaam, Tanzania; 2Family Medicine, The Aga Khan Hospital, Dar es Salaam, Tanzania & Aga Khan University, Medical College, East Africa, Dar-es-Salaam, Tanzania; 3Infectious Disease & Internal Medicine, The Aga Khan University, Medical College, Nairobi, Kenya; 4Pulmonology & Internal Medicine, Texas a&m University, Texas A&M College Station, TX, USA; 5Population Health, Aga Khan University, Medical College, East Africa, Nairobi, KenyaCorrespondence: Nadeem Kassam Email nadeem.kassam@aku.eduBackground: The emergence of the novel coronavirus disease 2019 (COVID-19) has caused millions of deaths worldwide. There has been paucity of data for hospitalized African patients suffering from COVID-19. This study aimed to identify factors associated with in-hospital mortality in patients suffering from COVID-19 in Tanzania.Methods: This was a single center, retrospective, observational cohort study in adult patients hospitalized with confirmed COVID-19 infection. Demographics, clinical pattern, laboratory and radiological investigations associated with increased odds of mortality were analyzed.Results: Of the 157 patients, 107 (68.1%) patients survived and 50 (31.8%) died. Mortality was highest in patients suffering with severe (26%) and critical (68%) forms of the disease. The median age of the cohort was 52 years (IQR 42– 61), majority of patients were male (86%) and of African origin (46%), who presented with fever (69%), cough (62%) and difficulty in breathing (43%). Factors that were associated with mortality among our cohort were advanced age (OR 1.07, 95% CI 1.03– 1.11), being overweight and obese (OR 9.44, 95% CI 2.71– 41.0), suffering with severe form of the disease (OR 4.77, 95% CI 1.18– 25.0) and being admitted to the HDU and ICU (OR 6.68, 95% CI 2.06– 24.6).Conclusion: The overall in-hospital mortality was 31.8%. Older age, obesity, the severe form of the disease and admission to the ICU and HDU were major risk factors associated with in-hospital mortality.Keywords: COVID-19, factors, hospital, mortality, Tanzania

The negatively-charged nitrogen-vacancy (NV) center is the most studied optical center in diamond and is very important for applications in quantum information science. Many proposals for integrating NV centers in quantum and sensing applications rely on their tailored fabrication in ultra pure host material. In this study, we use ion implantation to controllably introduce nitrogen into high purity, low nitrogen chemical vapor deposition diamond samples. The properties of the resulting NV centers are studied as a function of implantation temperature, annealing temperature, and implantation fluence. We compare the implanted NV centers with native NV centers present deep in the bulk of the as-grown samples. The results for implanted NV centers are promising but indicate, at this stage, that the deep native NV centers possess overall superior optical properties. In particular, the implanted NV centers obtained after annealing at 2000 °C under a stabilizing pressure of 8 GPa showed an ensemble linewidth of 0.17 nm compared to 0.61 nm after annealing at 1000 °C. Over the same temperature range, the ensemble NV-/NV0 ratio increased by a factor of ∼5, although this was accompanied by an overall decrease in the NV count. [ABSTRACT FROM AUTHOR]

Ni-related optical centres in diamond are promising as alternatives to the nitrogen vacancy (NV) centre for quantum applications and biomarking. In order to achieve the reliability and reproducibility required, a method for producing the Ni-related centres in a controllable manner needs to be established. In this study, we have attempted this control by implanting high purity CVD diamond samples with Ni and N followed by thermal annealing. Samples implanted with Ni show a new Ni-related PL peak centered at 711 nm and a well known doublet at 883/885 nm along with weak NV luminescence. The optical properties of the two Ni-related defects are investigated. In particular, an excited state lifetime of the 883/885 nm peak is measured to be 11.6 ns. [ABSTRACT FROM AUTHOR]

The thermal stability of nanocrystalline diamond films with 10-30 nm grain size deposited by microwave enhanced chemical vapor deposition on silicon substrate was investigated as a function of annealing temperature up to 1200 °C. The thermal stability of the surface-upper atomic layers was studied with near edge x-ray absorption fine structure (NEXAFS) spectroscopy recorded in the partial electron yield mode. This technique indicated substantial thermally induced graphitization of the film within a close proximity to the surface. While in the bulk region of the film no graphitization was observed with either Raman spectroscopy or NEXAFS spectroscopy recorded in total electron yield mode, even after annealing to 1200 °C. Raman spectroscopy did detect the complete disappearance of transpolyacetylene (t-PA)-like ν1 and ν3 modes following annealing at 1000 °C. Secondary ion mass spectroscopy, applied to investigate this relative decrease in hydrogen atom concentration detected only a ∼30% decrease in the bulk content of hydrogen atoms. This enhanced stability of sp3 hybridized atoms within the bulk region with respect to graphitization is discussed in terms of carbon bond rearrangement due to the thermal decomposition of t-PA-like fragments. [ABSTRACT FROM AUTHOR]

Carbon ions of MeV energy were implanted into sapphire to fluences of 1×1017 or 2×1017 cm-2 and thermally annealed in forming gas (4% H in Ar) for 1 h. Secondary ion mass spectroscopy results obtained from the lower dose implant showed retention of implanted carbon and accumulation of H near the end of range in the C implanted and annealed sample. Three distinct regions were identified by transmission electron microscopy of the implanted region in the higher dose implant. First, in the near surface region, was a low damage region (L1) composed of crystalline sapphire and a high density of plateletlike defects. Underneath this was a thin, highly damaged and amorphized region (L2) near the end of range in which a mixture of i-carbon and nanodiamond phases are present. Finally, there was a pristine, undamaged sapphire region (L3) beyond the end of range. In the annealed sample some evidence of the presence of diamond nanoclusters was found deep within the implanted layer near the projected range of the C ions. These results are compared with our previous work on carbon implanted quartz in which nanodiamond phases were formed only a few tens of nanometers from the surface, a considerable distance from the projected range of the ions, suggesting that significant out diffusion of the implanted carbon had occurred. [ABSTRACT FROM AUTHOR]

The influence of high temperature annealing up to 1200 °C in vacuum on ∼100 nm nearly continuous thick diamond films consisting of 30–50 nm crystallites, deposited onto silicon substrates is reported. The hydrogen bonding and phase composition of the films were studied with Raman spectroscopy, while the surface microstructure and composition were studied with high resolution scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS), respectively. Annealing to 800–900 °C of ∼100 nm thick films results in a decrease in the intensities of the peaks associated with hydrogen bonding (Raman), as well as changes to the morphological microstructure at the film surface. Heating the films to 1000 °C resulted in the complete disappearance of the Raman peaks associated with hydrogen bonding at grain boundaries, and an increase in the relative intensity of the diamond peak relative to the graphite-related D and G Raman peaks, concomitant with changes to the microstructure (SEM and TEM). Ex situ XP analysis of the films annealed to 800 and 1000 °C provides clear evidence for the formation of SiC on the films surface and near surface region. However a sharp SiC Raman peak at 796 cm-1 appears only after annealing to 1200 °C and it is concomitant with a decrease in the Raman peaks associated with sp2 bonded carbon. Our results suggest that formation of SiC phase preferentially consumes sp2/sp hybridized carbon matrix, produced by thermal desorption of hydrogen atoms at diamond grain boundary and at the diamond film—silicon substrate interface. [ABSTRACT FROM AUTHOR]

MeV carbon ion implantation followed by thermal annealing in a hydrogen-containing atmosphere produces a layer of diamond nanocrystals within fused quartz (SiO2). Cathodoluminescence (CL) microanalysis in a scanning electron microscope has revealed at least three previously unreported low intensity CL emissions from carbon implanted and thermally annealed fused SiO2. The CL emissions are observed at 2.78 eV [full width at half maximum (FWHM) of 0.08 eV], ∼3 eV (FWHM of 0.4 eV), and 3.18 eV (FWHM of 0.11 eV). The peak widths and energies of these emissions are incompatible with any known defects associated with the silicon dioxide host lattice. Nondestructive depth resolved CL microanalysis investigations confirm that these CL emissions originate from the near-surface region, consistent with their association with the layer of diamond nanocrystals. [ABSTRACT FROM AUTHOR]

Polarity-dependent forming in ion bombarded metal–semiconductor–metal (MSM) memory devices of hydrogenated amorphous silicon is reported. It is shown that prior to ion bombardment, current transport in the MSM devices is asymmetric and is controlled by the Schottky barriers at two MS junctions. Upon bombardment, however, there is a bulk component to the current and the I–V characteristics of the devices become symmetric at low bias voltages. The forming voltage in the bombarded devices shows polarity dependence. For positive bias applied on the top contact, we find that devices form at the same electric field independent of the thickness of the amorphous silicon while for negative voltage on the top contact, the electric field needed for forming increases with the thickness. A model involving the difference in energy deposition and heat sinking for the two polarities is proposed. [ABSTRACT FROM AUTHOR]

The electrical properties of hydrogenated amorphous silicon (a-Si:H) metal–semiconductor–metal (MSM) devices are investigated as a function of Si bombardment dose prior to and after annealing. We observe that conduction in unbombarded devices is surface-barrier controlled whereas it is bulk controlled in bombarded devices. The resistance decreases with bombardment dose in a manner consistent with increased hopping conductivity in highly damaged structures. A relative permittivity of between 8 and 12, depending on dose, was calculated from experimental Poole–Frenkel plots for bombarded devices. These values compare closely with the theoretical relative permittivity for amorphous silicon of 11.7 and confirm that conduction is by Poole–Frenkel mechanism. For bulk-controlled conduction, we observe an increase in the zero-field Coulombic trap barrier height with decreasing dose, ranging from 0.53 for a Si dose of 5×1013 cm-2 to 0.89 for a dose of 2×1012 cm-2. We attribute this to a decrease in the concentration of charged defects with decreasing dose and find that the change in concentration of charged centers needs to be about 4×1019 cm-3 to account for the change of 0.35 eV from the lower to the upper dose. Activation energies obtained from Arrhenius plots of current density against temperature varied with dose and temperature in a similar way as Coulombic barrier height. We explain these results in terms of the variation in the number of charged defect centers with dose and annealing temperature and a shift in the Fermi level. [ABSTRACT FROM AUTHOR]

Several studies are conducted to determine the bulk and surface thermal stability exhibited by the ultra nanocrystalline diamond films with 10-30 nm grain size.

Presents a study that examined the transport properties of the two-dimensional electron gas in selectively doped Al[suby]Ga[sub1-y]As/In [subx]Ga[sub1-x]As/GaAs pseudomorphic structures grown by molecular beam epitaxy. Experimental details; Results of the study; Conclusion.