Yapay burun : optofluidic fotonik Bragg fiberleri ile uçucu organik bileşiklerin teşhisi

Cataloged from PDF version of article.Thesis (M.S.): Bilkent University, Department of Materials Science and Nanotechnology, İhsan Doğramacı Bilkent University, 2016.Includes bibliographical references (leaves 66-77).Artificial nose system, comprising of a bundle of photonic Bragg fibers used for identification of industrial toxic gases is reported. The system, otherwise known as optoelectronic nose, harvests the unique infrared spectrum of volatile organic compounds (VOCs), in conjunction to a fabricated multilayered photonic Bragg fibers that filters the incident spectrum of the infrared to a narrow transmission band. The sensing mechanism of the device comprises the measurement of infrared absorption of volatile analytes inside the hollow cores of opto uidic Bragg fibers. An array of six fibers is used, where each fiber target a different region of the midinfrared in the range of 2-14 m with transmission bandwidths of about 1-3 m. The quenching in the transmission of each fiber due to the presence of analyte molecules in the hollow core is measured separately and the cross response of the array allows the identification of virtually any (VOC). The device was used for the identification of seven industrial VOC vapors with high selectivity using a standard blackbody source and an infrared detector. The array response is registered as a unique six digit binary code for each analyte by assigning a threshold value to the fiber transmissions. The developed prototype is a comprehensive and versatile artificial nose that is applicable to a wide range of analytes.by Abubakar Isa Adamu.M.S

Value Relevance of Accounting Information: Empirical Evidence from Listed Conglomerate Firms in Nigeria

In recent years, internal and external investors have lost confidence in Nigeria due to insecurity, energy (power), economic instability, and governance. Although the government is trying to overcome the menace, there are still unresolved issues in the aspect of the challenges above, which affect value relevance and accounting information in ensuring the perpetual existence of companies in Nigeria. As such, the study examined the value relevance of accounting information of listed conglomerate companies in Nigeria. The study population comprises six companies: UAC Nigeria Plc, Chellarams Plc, SCOA Nigeria Plc, John Holt Plc, Transnational Corporation of Nigeria Plc, and Custodian Investment Plc. The data was extracted from their annual report and accounts. Descriptive statistics correlation regression was conducted in the study. The result shows that return on share price has a significant negative relationship with dividend per share. The study recommends that standards comply in reporting and disclosing all accounting information in the published financial statement to maintain value relevance and attract more investors

Performance Evaluation of Tamarindus Indica Seeds Powder in the Treatment of Dye Wastewater

A large amount of dye wastewater is generated after the local dyeing process. It contains high concentrations of organic and inorganic contaminants. Furthermore, the composition of the wastewater varies according to the type and number of textiles and the water requirements of the process. Hence, its treatment before discharge is necessary to protect the environment. This study investigated the use and effectiveness of Tamarindus indica seeds powder from agricultural waste for removing some recalcitrant target compounds in the dye wastewater. A batch test was performed to examine the use of this adsorbent as a potential replacement for the advanced treatment methods. Varying adsorbent dosages determined the maximum adsorption capacity at 30, 35, 40, 45, and 50 g and at 24, 48, 72, 96 and 120 hr reaction times. The optimum dosage, reaction time and percentage removal of various parameters were found to be; Turbidity (no significant effect), TDS (40 g/l, 72 hrs, 54.42%), EC (35 g/l, 72 hrs, 4.46%), Phosphate (35 g/l, 24 hrs, 38.49 %), Total suspended solid (no significant effect), Nitrate (30 g/l, 96 hrs, 15.26%), COD (no considerable impact) and BOD (30 g/l, 48 hrs, 63.38%) respectively. The results showed that adsorption efficiency increased with decreased adsorbent dosage, even at different reaction times. Hence, low-cost adsorbents such as Tamarindus indica seeds can treat dye waste water to a certain level for safe disposal

Factors associated with abnormal glomerular filtration rate among HIV-positive children at the University of Maiduguri Teaching Hospital, Maiduguri, Nigeria

Background: Renal disease is commonly encountered in patients with HIV infection. The estimated glomerular filtration rate (eGFR) provides a good assessment of the renal function and is widely used in screening populations that are at risk of renal dysfunction. We determined the prevalence of abnormal eGFR among HIV-positive children and factors associated with it.Methods: In a cross-sectional study, children aged 15 years and below were recruited through systematic random sampling from the Paediatrics Infectious Disease Clinic of the University of Maiduguri Teaching Hospital until the desired sample size of 250 was reached. Clinical and laboratory information was obtained from the patient records and used for clinical staging and immunological classification. Serum creatinine was measured using Jaffe’s reaction and eGFR calculated using the Schwartz formula. The data obtained were analysed using SPSS version 16.Results: A total of 157 (62.8%) children were on antiretroviral therapy (HAART) for periods ranging from 1 to 168 months (mean duration 66.1 ± 46.5 months). Ninety-three (37.2%) children had advanced disease representing WHO clinical stages 3 and 4, whereas 103 (41.2%) had advanced or severe immunosuppression. The mean eGFR of the study population was 102 ± 41 mL/min/1.73 m2. Fifty-two children (20.1%) had low eGFR (<2 SD below the mean eGFR for age and sex) and 6 (2.4%) had high eGFR (>2 SD above the mean eGFR for age and sex). A total of 23 (9.2%) children had moderate to severe renal impairment, defined as eGFR <60 mL/min/1.73 m2. Age, sex, socio-economic status, mode of transmission as well as history of HAART usage were not significantly associated with abnormal eGFR. However, relatively shorter duration of treatment with HAART, as well as advanced clinical or immunological stage were all significantly associated with abnormal eGFR.Conclusion: Renal dysfunction is common among children with HIV disease in Maiduguri with over a third of those affected having moderate to severe renal dysfunction. Abnormal renal function is more frequent among children with advanced clinical and immunological disease. We recommend the regular determination of eGFR and early initiation of HAART in all children with HIV disease

High mortality among tuberculosis patients on treatment in Nigeria: a retrospective cohort study.

BACKGROUND: Tuberculosis (TB) remains a leading cause of death in much of sub-Saharan Africa despite available effective treatment. Prompt initiation of TB treatment and access to antiretroviral therapy (ART) remains vital to the success of TB control. We assessed time to mortality after treatment onset using data from a large treatment centre in Nigeria. METHODS: We analysed a retrospective cohort of TB patients that commenced treatment between January 2010 and December 2014 in Aminu Kano Teaching Hospital. We estimated mortality rates per person-months at risk (pm). Cox proportional hazards model was used to determine risk factors for mortality. RESULTS: Among 1,424 patients with a median age of 36.6 years, 237 patients (16.6%) died after commencing TB treatment giving a mortality rate of 3.68 per 100 pm of treatment in this cohort. Most deaths occurred soon after treatment onset with a mortality rate of 37.6 per 100 pm in the 1st week of treatment. Risk factors for death were being HIV-positive but not on anti-retroviral treatment (ART) (aHR 1.39(1 · 04-1 · 85)), residence outside the city (aHR 3 · 18(2.28-4.45)), previous TB treatment (aHR 3.48(2.54-4.77)), no microbiological confirmation (aHR 4.96(2.69-9.17)), having both pulmonary and extra-pulmonary TB (aHR 1.45(1.03-2.02), and referral from a non-programme linked clinic/centre (aHR 3.02(2.01-4.53)). CONCLUSIONS: We attribute early deaths in this relatively young cohort to delay in diagnosis and treatment of TB, inadequate treatment of drug-resistant TB, and poor ART access. Considerable expansion and improvement in quality of diagnosis and treatment services for TB and HIV are needed to achieve the sustainable development goal of reducing TB deaths by 95% by 2035

Noise performance and long-term stability of near- and mid-IR gas-filled fiber Raman lasers

In this letter, the characteristics of noise and long-term stability of near- and mid-infrared (near-IR and mid-IR) gas-filled fiber Raman lasers have been investigated for the first time. The results reveal that an increase in Raman pulse energy is associated with a decrease in noise, and that the relative pulse peak intensity noise (RIN) is always lower than the relative pulse energy noise (REN). We also demonstrate that long-term drift of the pulse energy and peak power are directly linked with the high amount of heat release during the Raman Stokes generation. The demonstrated noise and long-term stability performance provide necessary references for potential spectroscopic applications as well as further improvements of the emerging mid-IR gas-filled hollow-core fiber (HCF) Raman laser technology

Evaluation of anti-inflammatory, antibacterial and cytotoxic activities of Cordia africana leaf and stem bark extracts

Cordia africana (Boraginaceae) is a tree used in traditional medicine to treat inflammation related conditions and infectious diseases. This study was undertaken with the objectives of establishing the scavenging effect of extracts and fractions of Codia africana on the mediator of inflammation Lipoxygenases (LOX), and some non-biological free radicals such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), the [2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) radicals and the Ferric ion reducing antioxidant power (FRAP). Antimicrobial activities, total phenolics/flavonoids and cytotoxicity of extracts of Codia africana were also evaluated. Extracts were obtained by maceration. Anti-inflammatory activity was determined using a LOX-inhibitor screening assay kit according to the manufacturer's instructions. A broth serial micro dilution method was used to determine the minimum inhibitory concentration (MIC) against, Gram-positive and Gram-negative bacteria and Mycobacterium species. The antioxidant activity was determined using free-radical-scavenging assays, and the 3-(4,5- dimethylthiazolyl-2)-2,5- diphenyltetrazolium bromide reduction assay was used for cytotoxicity. Both the extracts of C. africana inhibited LOX enzyme. The most active being the methanol extract of the bark with IC50 value of 55 ± 0.9 μg/ml. Both the extracts of C. africana, had excellent to weak antimicrobial activites (MICs ranging from 32 to 1024 μg/ml) against bacteria. All the extracts had significant (P< 0.05) free-radical scavenging activity (IC50 ranging from 6.79 ± 0.07 to 331.98 ± 0.07 μg/ml). There was a positive correlation between the antioxidant activity and the total flavonoid and total phenolic contents of Cordia africana. The cytotoxicity on Vero cells was low with LC50 of 81.79 ± 13.31 and 99.67 ± 16.10 μg/ml. The results support the use of C. africana leaves in traditional medicine to treat inflammation related conditions and infectious diseases.Keywords: Cordia Africana, Inflammation, antibacterial, antioxidant, total flavonoid