Mohammed Al-Abri

Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO) nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC) was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

Effects of overweight and leisure-time activities on aerobic fitness in urban and rural adolescents.

BACKGROUND The aim of this research was to study the effects of overweight and leisure-time activities on maximal aerobic capacity (VO(2)max) in urban and rural Omani adolescents. METHODS A total of 529 (245 males, 284 females) adolescents, aged 15-16 years were randomly selected from segregated urban and rural schools. Maximal aerobic capacity was estimated using the multistage 20-meter shuttle-run test. RESULTS The body mass index (BMI) of urban boys and girls was significantly higher than that of rural boys and girls. Urban boys and girls spent significantly less weekly hours on sports activities and significantly more weekly hours on TV/computer games than their rural counterpart. Urban boys and girls achieved significantly less VO(2)max than rural boys and girls (44.2 and 33.0 vs. 48.3 and 38.6 mL/kg/min, respectively). Maximal aerobic capacity was negatively correlated with BMI in urban boys. CONCLUSION Overweight and inactivity had significant negative effects on cardiorespiratory fitness in urban boys and girls as compared to their rural counterparts. Weight gain in adolescence requires early intervention.

Association of gene variants with susceptibility to type 2 diabetes among Omanis

AIM To investigate the association of 10 known common gene variants with susceptibility to type 2 diabetes mellitus (T2D) among Omanis. METHODS Using case-control design, a total of 992 diabetic patients and 294 normoglycemic Omani Arabs were genotyped, by an allelic discrimination assay-by-design TaqMan method on fast real time polymerase chain reaction system, for the following gene variants: KCNJ11 (rs5219), TCF7L2 (rs7903146), CDKAL1 (rs10946398), CDKN2A/B (rs10811661), FTO (rs9939609 and rs8050136), IGF2BP2 (rs4402960), SLC30A8 (rs13266634) CAPN10 (rs3792267) and HHEX (rs1111875). T2D patients were recruited from the Diabetes Clinic (n = 243) and inpatients (n = 749) at Sultan Qaboos Univesity Hospital (SQUH), Muscat, Oman. Adult control participants (n = 294) were volunteers from the community and from those visiting Family Medicine Clinic at SQU, for regular medical checkup. The difficulty in recruiting Omani participants with no family history of diabetes was the main reason behind the small number of control participants in this study. Almost all volunteers questioned had a relative with diabetes mellitus. Inspite of the small number of normoglycemic controls in this study, this sample was sufficient for detection of genes and loci for common alleles influencing T2D with an odds ratio of ≥ 1.3 reaching at least 80% power. Data was collected from June 2010 to February 2012. RESULTS Using binary logistic regression analysis, four gene variants showed significant association with T2D risk: KCNJ11 (rs5219, P = 5.8 × 10(-6), OR = 1.74), TCF7L2 (rs7903146, P = 0.001, OR = 1.46), CDKAL1 (rs10946398, P = 0.002, OR = 1.44) and CDKN2A/B (rs10811661, P = 0.020, OR = 1.40). The fixation index analysis of these four gene variants indicated significant genetic differentiation between diabetics and controls {[KCNJ11 (rs5219), P < 0.001], [TCF7L2 (rs7903146), P < 0.001], [CDKAL1 (rs10946398), P < 0.05], [CDKN2A/B (rs10811661), P < 0.05]}. The highest genotype variation % between diabetics and controls was found at KCNJ11 (2.07%) and TCF7L2 (1.62%). This study was not able to detect an association of T2D risk with gene variants of IGF2BP2 (rs4402960), SLC30A8 (rs13266634), CAPN10 (rs3792267) and HHEX (rs1111875). Moreover, no association was found between FTO gene variants (rs9939609 and rs8050136) and T2D risk. However, T2D risk was found to be significantly associated with obesity (P = 0.002, OR = 2.22); and with the Waist-to-Hip ratio (n = 532, P = 1.9 ×10(-7), OR = 2.4), [among males (n = 234, P = 1.2 × 10(-4), OR = 2.0) and females (n = 298, P = 0.001, OR = 6.3)]. CONCLUSION Results confirmed the association of KCNJ11 (rs5219), TCF7L2 (rs7903146), CDKAL1 (rs10946398) and CDKN2A/B (rs10811661) gene variants with susceptibility to T2D among Omani Arabs.

Enhanced Membrane Pre¿Treatment Processes using Macromolecular Adsorption and Coagulation in Desalination Plants: A Review

Abstract Recent advances in membrane technology have prompted the rapid growth of the Reverse Osmosis (RO) desalination in comparison to other water desalination technologies. One of the major problems of RO is fouling which leads to major reduction in the efficiency of this process. RO membranes are usually fouled with colloids, humic substances, micro‐organisms, and heavy metals. This is why it is critical to treat the feed water prior to RO filtration. Conventional pre‐treatment methods include processes such as coagulation, adsorption, sedimentation, flotation, sand filtration, disinfection, and the addition of anti‐scalants. Recently, membrane pre-treatment processes including micro‐filtration (MF), ultrafiltration (UF) and nanofiltration have been introduced prior to RO, with or as a replacement for conventional pre‐treatment. These processes are useful in providing feed water superior in quality to conventional pre‐treatment, but they are limited in the range of pollutant removal and operating conditions. Full description of water composition and the interactions and aggregations between the contaminants found in feed water for RO desalination is shown in this review. The review includes introduction to membranes, including retention and fouling mechanisms, conventional and membrane pre‐treatment, and membrane backwashing. It also highlights the role of coagulation and adsorption in the pre‐treatment process and the impact of integration of coagulation and/or adsorption with membrane pre‐treatment.

Combined humic substance and heavy metals agglomeration, and membrane filtration under saline conditions

Abstract Humic substances‐heavy metals complexation combined with membrane filtration is reported. The effects of salinity, humic substances (HS) concentration, heavy metals concentration, and trans‐membrane pressure (TMP) on HS and heavy metals retention using two membranes are studied. Membrane fouling is also studied at the aforementioned conditions. NF270 experienced higher fouling. Moreover, salinity tests showed increasing fouling rate and reduction in membrane retention with increasing salinity level. While increasing HS concentration reduced HS retention and increased heavy metals retention and membrane fouling. Heavy metals concentration reduced the NF270 HS retention, but did not affect the P005F HS retention. In addition, TMP did not affect HS and heavy metals retention nor NF270 fouling, but increased P005F fouling.

Frequency of Obstructive Sleep Apnea Syndrome Among Patients with Epilepsy Attending a Tertiary Neurology Clinic

OBJECTIVES Epilepsy is a common neurological disorder with a median lifetime prevalence of 14 per 1000 subjects. Sleep disorders could influence epileptic seizure. The most common sleep disorder is obstructive sleep apnea syndrome (OSAS) which occurs in 2% of adult women and 4% of adult men in the general population. The aim of this study is to estimate the frequency of OSAS among patients with epilepsy and to study the seizure characteristics among those patients with co-morbid OSAS. METHODS Patients with a confirmed diagnosis of epilepsy who attended the Sultan Qaboos University Hospital neurology clinic were recruited for the study between June 2011 and April 2012. Patients were screened for OSAS by direct interview using the validated Arabic version of the Berlin questionnaire. Patients identified as high-risk underwent polysomnography. RESULTS A total of 100 patients with epilepsy (55 men and 45 women) were screened for OSAS. Generalized and focal seizure was found in 67% of male and 27% of female patients. Six percent of the participants had epilepsy of undetermined type. Only 9% of the sample was found to have high risk of OSAS based on the Berlin questionnaire. No significant correlation was found between risk of OSAS, type of epilepsy, and anti-epileptic drugs. CONCLUSION The risk of OSAS was marginally greater in patients with epilepsy compared to the general population with the overall prevalence of 9%.

Classification of sleep apnea using wavelet-based spectral analysis of heart rate variability

BACKGROUND Obstructive Sleep Apnea (OSA) is the cessation of breathing during sleep due to the collapse of upper airway. Polysomnographic recording is a conventional method for detection of OSA. Although it provides reliable results, it is expensive and cumbersome. Thus, an advanced non-invasive signal processing based technique is needed. OBJECTIVE The main purpose of this work is to predict the severity of sleep apnea using an efficient wavelet-based spectral analysis method of the heart rate variability (HRV) to classify sleep apnea into three different levels (mild, moderate, and severe) according to its severity and to distinguish them from normal subjects. METHODS The standard FFT spectrum analysis method and the soft-decision wavelet-based technique are to be used in this work in order to rank patients to full polysomnography. Data of 20 normal subjects and 20 patients with mild apnea and 20 patients with moderate apnea and 20 patients of severe apnea are used in this study. The data is obtained from the sleep laboratory of Sultan Qaboos University hospital in Oman. Four different classification versions have been used in this work. RESULTS Accuracy result of 90% was obtained between severe and normal subjects and 85% between mild and normal and 75% between severe and moderate and 83.75% between normal and patients. CONCLUSIONS The VLF/LF power spectral ratio of the wavelet-based soft-decision analysis of the RRI data after a high-pass filter resulted in the best accuracy of classification in all versions.

Efficient visible light photocatalysis of benzene, toluene, ethylbenzene and xylene (BTEX) in aqueous solutions using supported zinc oxide nanorods

Benzene, toluene, ethylbenzene and xylenes (BTEX) are some of the common environmental pollutants originating mainly from oil and gas industries, which are toxic to human as well as other living organisms in the ecosystem. Here we investigate photocatalytic degradation of BTEX under visible light irradiation using supported zinc oxide (ZnO) nanorods grown on glass substrates using a microwave assisted hydrothermal method. ZnO nanorods were characterized by electron microscopy, X-ray diffraction (XRD), specific surface area, UV/visible absorption and photoluminescence spectroscopy. Visible light photocatalytic degradation products of BTEX are studied for individual components using gas chromatograph/mass spectrometer (GC/MS). ZnO nanorods with significant amount of electronic defect states, due to the fast crystallization of the nanorods under microwave irradiation, exhibited efficient degradation of BTEX under visible light, degrading more than 80% of the individual BTEX components in 180 minutes. Effect of initial concentration of BTEX as individual components is also probed and the photocatalytic activity of the ZnO nanorods in different conditions is explored. Formation of intermediate byproducts such as phenol, benzyl alcohol, benzaldehyde and benzoic acid were confirmed by our HPLC analysis which could be due to the photocatalytic degradation of BTEX. Carbon dioxide was evaluated and showed an increasing pattern over time indicating the mineralization process confirming the conversion of toxic organic compounds into benign products.

Validation of the arabic version of the epworth sleepiness scale in oman.

OBJECTIVES The Epworth sleepiness scale is a self-administered eight-item questionnaire that was developed as a tool to measure subjective sleepiness in adults. The validity of the Epworth sleepiness scale has been validated and tested in different populations and ethnic groups. However, it has yet to be validated or tested in an Omani or other Arabic speaking population. Thus, the aim of this study is to test the validity and reproducibility of the Epworth sleepiness scale in an Omani population. METHODS Subjects were recruited from the general population and were asked to participate in the study. The study enrolled 97 Omani volunteers and was conducted between May and October 2008. An Arabic version of the original English questionnaire was used. The study was approved by the Research and Ethics committee of the institution. Lins concordance correlation coefficient along with Bland-Altman plots were used to test the agreement between the Arabic and English versions of the Epworth sleepiness scale. RESULTS The study included a total of 37 males (38%) and 60 females (62%) with age ranging between 18-75 years. Concordance correlation results revealed a substantial concordance (RhoC) of 0.914, but one that does not approach 1 (95% CI: 0.881, 0.947). This results from both lack of perfect correlation (Pearsons r=0.914) and bias (C_b = 1.000). The Bland and Altmans limits-of-agreement measured at 0.000 (95% CI: -2.684, 2.684), indicating insignificant average departure from agreement between the two versions of the Epworth sleepiness scale. CONCLUSION The results indicate agreement between the two versions of ESS (English and the Arabic).

Investigation of heart rate variability of patients undergoing coronary artery bypass grafting (CABG)

BACKGROUND Myocardial revascularization by coronary artery bypass grafting (CABG) is an effective measure for reducing symptoms and mortality in patients with unstable or severe coronary artery disease (CAD). Autonomic function can be estimated non-invasively using heart rate variability (HRV). HRV of patients undergoing CABG is investigated before and after CABG using a soft-decision wavelet based spectral analysis. OBJECTIVE The main purpose of this work is to evaluate non-invasively HRV in patients undergoing CABG before operation; and to monitor the status of patients through HRV investigation on day 6 and day 30 after the CABG operation. The study intends to contribute scientific value to understanding the effect of CABG on the cardiovascular autonomic function and surgical outcome. METHODS The soft-decision wavelet-based technique is used in this work in order to measure the power spectral density of the three main bands (VLF, LF, and HF) of HRV in 24 patients undergoing CABG operation, before the operation (Group 1: G1), and 6 days after operation (Group 2: G2) and 30 days after operation (Group 3: G3). The data is obtained from Sultan Qaboos University hospital in Oman. RESULTS The HF power increases in 22 out of 24 patients in G2 compared to G1. While the LF power decreases in 21 out of 24 patients in G2 compared to G1. Comparing G3 to G1 the LF power decreases in 20 patients. The sum of the VLF and LF power is reduced in G2 in all 24 subjects compared to G1, and in 19 subjects in G3 compared to G1. CONCLUSIONS The power spectral density of the HF shows increase in patients recorded on day 6 after operation compared to patients before the operation. The LF shows a decrease in G2 compared to G1. The results of G3 after 30 days of operation still show an increase of the HF power and a decrease in the LF power in most of the patients compared to their values before operation.