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Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application

Reshak AH, Shahimin MM, Shaari S, Johan N

Prog Biophys Mol Biol, 2013 Nov;113(2):327-32.
PMID: 24139943 DOI: 10.1016/j.pbiomolbio.2013.10.002

The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.
End-stage kidney disease in Brunei Darussalam (2011-2020)

Johan NH, Oo AP, Pisharam JK, Rosalina S, Koh D, Tan J

Med J Malaysia, 2023 Jan;78(1):54-60.
PMID: 36715192

INTRODUCTION: The Brunei Dialysis and Transplant Registry (BDTR) recorded data on patients with end-stage kidney disease (ESKD) from 2011 to 2020, mainly for planning of services and benchmarking of standards. We report the trends of epidemiologic and performance parameters, compare performances between modalities of Kidney Replacement Therapy and evaluate the survival of ESKD patients over the 10-year period.
MATERIALS AND METHODS: Three groups of data were analysed from the BDTR over the 10-year period. Epidemiological data, blood parameters and dialysis are key performance indicators.
RESULTS: There are increments in prevalence and incidence of treated ESKD patients in Brunei over 10 years, especially with haemodialysis (HD). The projected prevalence and incidence showed an anticipated annual increase of 42.2 per million population (pmp) and 9.9 pmp respectively. Diabetes mellitus (DM) (79%) was the main cause of ESKD. HD (86%), peritoneal dialysis (PD) (9%) and transplant (5%) were the main modalities of kidney replacement therapy in 2020. Cumulative results over the decade showed significant improvements in serum phosphate, peritonitis rates and HD blood flow rates. PD patients have better survival rates, lower systolic blood pressure and better adequacy. PD survival (patient survival of 91%, 73% and 56% at 1, 3 and 5 years respectively) was superior to HD survival (86% and 64% at 1 and 2 years, respectively), but patient demographics (age and DM status) were different. The 2020 dataset showed satisfactory anaemia management but mineral bone disease management was sub-optimal. Seventy percent of prevalent HD patients had arteriovenous fistula access. Thirty-two percent and fifty-two percent of HD and PD patients, respectively, achieved target dialysis adequacy. Peritonitis rate was 0.3 episodes per patient year.
CONCLUSION: Brunei has a high incidence and prevalence of treated ESKD in the last decade, especially DM-related ESKD. This study has identified many specific areas to be targeted for improvements and provided evidence for further proliferation of PD and transplant preference policy.
The variability of lower third molar development in Northeast Malaysian population with application to age estimation

Johan NA, Khamis MF, Abdul Jamal NS, Ahmad B, Mahanani ES

J Forensic Odontostomatol, 2012 Jul;30(1):45-54.
PMID: 23000811

This study aimed to assess the variability of the lower third molar (tooth 38 and 48) development in Northeast Malaysian population with respect to the side of dentition, to generate age prediction models and to compare the outcome with other studies. A total of 1080 orthopantomograms of Northeast Malaysian population aged between 14 and 25 years (540 males and 540 females) from the Hospital Universiti Sains Malaysia's archive which met the inclusion and exclusion criteria were selected and the maturity stages of tooth 38 and 48 were scored using Demirjian's stages (A-H). The findings showed a wide variation of the development of lower third molars in the Northeast Malaysian population. The roots developed earlier in males than in females. The development of the dentition on opposite sides of the mandible was synchronously in females and males. A multiple regression analysis shows that 71.1% of variance in age was explained by sex and developmental stage of tooth 48. An age prediction model was generated from the regression analysis: [Age = 7.117 + 1.907*(stage of tooth 48) - 0.432*(sex)] with mean prediction errors between -0.17 to 3.14 years. The obtained data in the current study are useful for references and determining age of unidentified human remains for identification investigation.
Fulltext Long-term exposure to ambient air pollution and incidence of brain tumor: the European Study of Cohorts for Air Pollution Effects (ESCAPE)

Andersen ZJ, Pedersen M, Weinmayr G, Stafoggia M, Galassi C, Jørgensen JT, et al.

Neuro-oncology, 2018 02 19;20(3):420-432.
PMID: 29016987 DOI: 10.1093/neuonc/nox163

Background: Epidemiological evidence on the association between ambient air pollution and brain tumor risk is sparse and inconsistent.
Methods: In 12 cohorts from 6 European countries, individual estimates of annual mean air pollution levels at the baseline residence were estimated by standardized land-use regression models developed within the ESCAPE and TRANSPHORM projects: particulate matter (PM) ≤2.5, ≤10, and 2.5-10 μm in diameter (PM2.5, PM10, and PMcoarse), PM2.5 absorbance, nitrogen oxides (NO2 and NOx) and elemental composition of PM. We estimated cohort-specific associations of air pollutant concentrations and traffic intensity with total, malignant, and nonmalignant brain tumor, in separate Cox regression models, adjusting for risk factors, and pooled cohort-specific estimates using random-effects meta-analyses.
Results: Of 282194 subjects from 12 cohorts, 466 developed malignant brain tumors during 12 years of follow-up. Six of the cohorts also had data on nonmalignant brain tumor, where among 106786 subjects, 366 developed brain tumor: 176 nonmalignant and 190 malignant. We found a positive, statistically nonsignificant association between malignant brain tumor and PM2.5 absorbance (hazard ratio and 95% CI: 1.67; 0.89-3.14 per 10-5/m3), and weak positive or null associations with the other pollutants. Hazard ratio for PM2.5 absorbance (1.01; 0.38-2.71 per 10-5/m3) and all other pollutants were lower for nonmalignant than for malignant brain tumors.
Conclusion: We found suggestive evidence of an association between long-term exposure to PM2.5 absorbance indicating traffic-related air pollution and malignant brain tumors, and no association with overall or nonmalignant brain tumors.