•Minimum stress of highly c-axis oriented ZnO was grown at suitable deposition speed.•The ZnO crystal orientation was influenced by strain/stress of the film.•Minimum stress/strain of ZnO film leads ...to lower defects.•Bandgap and defects were closely intertwined with strain/stress.•We report additional optical and electrical properties based on deposition speed.
Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposition speeds by a sonicated sol–gel dip-coating technique. This work studies the effects of deposition speed on the crystallisation behaviour and optical and electrical properties of the resulting films. X-ray diffraction (XRD) analysis showed that thin films were preferentially oriented along the (002) c-axis direction of the crystal. The transformation sequence of strain and stress effects in ZnO thin films has also been studied. The films deposited at a low deposition speed exhibited a large compressive stress of 0.78GPa, which decreased to 0.43GPa as the deposition speed increased to 40mm/min. Interestingly, the enhancement in the crystallinity of these films led to a significant reduction in compressive stress. All films exhibited an average transmittance of greater than 90% in the visible region, with absorption edges at ∼380nm. The photoluminescence (PL) measurements indicated that the intensity of the emission peaks varied significantly with deposition speed. The optical band gap energy (Eg) was evaluated as 3.276–3.289eV, which increased with decreasing compressive stress along the c-axis. The energy band gap of the resulting ZnO films was found to be strongly influenced by the preferred c-axis (002) orientation.
Herein we report a new microwave-assisted synthetic strategy to rapidly prepare hybrid zeolitic-imidazolate frameworks (ZIFs): ZIFs with mixed metal centers and/or mixed linkers. The microwave-based ...method significantly shortens synthesis time, produces a higher yield, substantially reduces the amounts of ligands, and eliminates the use of deprotonating agents. The X-ray diffraction pattern reveals that mixed metal CoZn-ZIF-8 (i.e., ZIF-8 with both Co and Zn centers) maintains the sodalite (SOD) zeolitic topology from the ZIF-8 parent. Elemental mapping using energy-dispersive X-ray spectroscopy (EDS) and electronic/geometric information obtained from X-ray absorption spectroscopy (XAS) confirm the uniform distribution of tetrahedral Co and Zn metal centers within the same framework of the mixed-metal ZIF. The metal to nitrogen (M-N) stretching frequencies of IR bands were observed to be systematically blue-shifted as the Co/Zn ratio in the mixed metal ZIF increases. Furthermore, for the first time, a hybrid ZIF with both mixed metal centers (Co and Zn) and mixed linkers (2-methylimidazolate and benzimidazolate) was prepared through one-step microwave synthesis. Finally, mixed metal CoZn-ZIF-8 with a Co/Zn ratio of similar to 1 was grown as membranes on porous alpha -Al2O3 supports, showing a higher propylene/propane separation factor ( similar to 120) when compared to pure Zn-ZIF-8 membranes ( similar to 63) prepared by a similar method.
The disc brake squeal is a very annoying sound which affects the customer comfort. The generation of this noise is considered as a structural dynamics and/or tribological problems of the pad-disc ...system. Unlike drum brake design, this system is exposed to external environmental sand particles, wear debris and water spray. Their presence into the disc and pad interface may create dynamic and physics phenomena induced by friction surface changes which lead to brake noise and vibration issues. Thus, this paper aims to investigate the effect of environmental sand particles (silica sand and road sand particles) with a range size of 100–150, 150–200 and 300–400µm on the brake squeal noise occurrences. The sensitivity of the sand particles to produce noise is correlated with the wear scar, friction coefficient and variation of brake operational parameters. It was concluded that the primary reason for the reduced squeal noise generation was contributed to the reduced COF with the particle embedment. The analysis of the particle size influence on the squeal occurrence indicated that a small size of silica sand particle produces less squeal occurrence than that of road sand particles. However, the biggest silica and sand particles seriously damage the pad surface and reduce consequently the real contact surface, inducing a decrease on the friction coefficient.
•COF increases with smaller grit particle size.•Strong effect of external particles on the reduction of brake squeal.•Increasing size of external particle induced a lower squeal sound level.•The natural presence of the sand particles in the pad/disc interface is essential for brake squeal reduction.
Diets rich in whole grain are associated with several health benefits. Little is known however, about whole grain consumption patterns in Malaysia. The aim of this study was to assess whole grain ...intakes and dietary source in Malaysian children and adolescents.
This analysis is from the MyBreakfast study, a national cross sectional study investigating eating habits among primary and secondary school children throughout Malaysia, conducted in 2013. Children (n = 5,165) and adolescents (n = 2,947) who completed two days of dietary assessment using a food record or recall respectively were included. The whole grain content of foods was estimated mainly through the use of quantitative ingredient declarations on food labels. All wholegrain foods were considered irrespective of the amount of whole grain they contained.
Overall, only 25% of children and 19% of adolescents were wholegrain consumers. Mean daily intakes in the total sample were 2.3g/d (SD 5.8 g/d) in children and 1.7 g/d (SD 4.7 g/d) in adolescents and in the consumer's only sample, mean intakes reached 9.1g/d (SD 8.6) and 9.2g/d (SD 7.1g/d) respectively. Wheat was the main grain source of whole grain while ready to eat breakfast cereals and hot cereals were the main food contributors. Less than 3% of the children and adolescents reached the US quantitative whole grain recommendation of 48 g/day.
Whole grain is consumed by only a minority of Malaysian children and adolescents and even among consumers, intakes are well below recommendations. Efforts are needed to firstly understand the barriers to whole grain consumption among Malaysian children in order to design effective health promotion initiatives to promote an increase in whole grain consumption.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Removal of ciprofloxacin (CIP) pollutant from wastewater using conventional process is particularly challenging due to poor removal efficiency. In this work, CIP was photocatalytically degraded using ...a porous ZnO/SnS2 photocatalyst prepared via microwaves. The influence of process parameters (e.g., pH, catalyst mass and initial CIP concentration) and radical scavengers on visible-light induced degradation of CIP on the catalyst was investigated. From the study, it was found that visible-light induced degradation of CIP on ZnO/SnS2 is a surface-mediated process and the reaction kinetics followed the Langmuir-Hinshelwood first-order kinetics. It was found that the optimum condition for CIP degradation was at pH of 6.1 and catalyst dosage of 500 mg L−1. Higher catalyst dosage however led to a decline in reaction rate due to light scattering effect and reduction in light penetration.
•Ciprofloxacin (CIP) was photocatalytically degraded using a porous ZnO/SnS2 photocatalyst prepared under microwaves.•The roles and effects of radical scavengers on CIP degradation were investigated.•Five primary transformation products of CIP degradation were identified with empirical and structural formulae were proposed.•CIP degradation was mainly initiated by the direct hole attack with predominant reaction site was the piperazine moiety.•The optimum condition for CIP degradation was at pH of 6.1 and catalyst dosage of 500 mg L−1.
Over the past three decades, chemical and biological water contamination has become a major concern, particularly in the industrialized world. Heavy metals, aromatic compounds, and dyes are among the ...harmful substances that contribute to water pollution, which jeopardies the human health. For this reason, it is of the utmost importance to locate methods for the cleanup of wastewater that are not genuinely effective. Owing to its non-toxicity, biodegradability, and biocompatibility, starch is a naturally occurring polysaccharide that scientists are looking into as a possible environmentally friendly material for sustainable water remediation. Starch could exhibit significant adsorption capabilities towards pollutants with the substitution of amide, amino, carboxyl, and other functional groups for hydroxyl groups. Starch derivatives may effectively remove contaminants such as oil, organic solvents, pesticides, heavy metals, dyes, and pharmaceutical pollutants by employing adsorption techniques at a rate greater than 90%. The maximal adsorption capacities of starch-based adsorbents for oil and organic solvents, pesticides, heavy metal ions, dyes, and pharmaceuticals are 13,000, 66, 2000, 25,000, and 782 mg/g, respectively. Although starch-based adsorbents have demonstrated a promising future for environmental wastewater treatment, additional research is required to optimize the technique before the starch-based adsorbent can be used in large-scale in situ wastewater treatment.
Causes of fatal construction accidents in Malaysia Hamid, A R A; Noor Azmi, M R A; Aminudin, E ...
IOP conference series. Earth and environmental science,
01/2019, Letnik:
220, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Malaysia has moved fast to keep pace with the changes of times as the country aspires to achieve strong economic growth and to chart its course as a developed nation by the year 2020. The ...construction industry is one of the important sectors for nations to develop our country's economy and thus able to improve our competitiveness. However, in line with the positive growth of the economy, the construction sector also contributes to the high accident fatality rate. Construction workers are often exposed to various inherent risks associated with working conditions on construction sites. Although various approaches have been implemented in order to prevent accidents, the statistic indicates further improvement need to be taken fast. The objective of the study is to analyse the statistics and causes of fatal accidents at construction sites in Malaysia. The study focuses on 129 fatal construction accident cases based on database and document kept by the Malaysian authority, such as Department of Occupational Safety and Health (DOSH) and Social Security Organisation (SOCSO). The collected data were analyzed using frequency analysis and content analysis. The analysis shows that the number of fatal accidents is increasing every year. In the last five years, statistic from SOCSO and DOSH has shown an increasing number of fatal accident cases for about 231.9% and 125.8% respectively. The top three causes of fatal construction accidents are unsafe methods, the unique nature of industry and job site conditions. Whereas, the leading sub-causes are work at high elevation, incorrect or no work procedure and failure of structure.
Migration is a global phenomenon growing in scope, and it can be associated with negative emotions such as sense of impending loss, fear of the unknown, and anxiety about those left at home. The ...objective of this exploratory study was to examine psychological distress and homesickness among Sudanese migrants in the United Arab Emirates (UAE). Participants were 1444 Sudanese migrants (
= 40.20; SD = 10.98). The Second Version of the Dundee Relocation Inventory was used to assess homesickness, and the 28-item General Health Questionnaire was used to measure psychological distress, depressive and anxiety symptoms, somatic symptoms, and social dysfunction. The results showed that older age and longer duration of residence in the UAE were associated with lower levels of homesickness, psychological distress, and depressive and anxiety symptoms. Further, homesickness was associated with higher psychological distress, somatic symptoms, and depressive and anxiety symptoms. Women and unemployed migrants had higher psychological distress, somatic symptoms, and depressive and anxiety symptoms compared with men and those employed, respectively. Being unmarried was associated with higher levels of depressive symptoms and homesickness, while those married or divorced/widowed showed lower levels of depressive symptoms and homesickness. It was concluded that there is a need to tackle unemployment among migrants in the UAE and address family reunion issues.
Various concentrations (0.01, 0.03 and 0.05 wt ratios) of graphene oxide (GO) nanosheets were doped into magnesium oxide (MgO) nanostructures using chemical precipitation technique. The objective was ...to study the effect of GO dopant concentrations on the catalytic and antibacterial behavior of fixed amount of MgO. XRD technique revealed cubic phase of MgO, while its crystalline nature was confirmed through SAED profiles. Functional groups presence and Mg-O (443 cm
−1
) in fingerprint region was evident with FTIR spectroscopy. Optical properties were recorded via UV–visible spectroscopy with redshift pointing to a decrease in band gap energy from 5.0 to 4.8 eV upon doping. Electron–hole recombination behavior was examined through photoluminescence (PL) spectroscopy. Raman spectra exhibited D band (1338 cm
−1
) and G band (1598 cm
−1
) evident to GO doping. Formation of nanostructure with cubic and hexagon morphology was confirmed with TEM, whereas interlayer average d-spacing of 0.23 nm was assessed using HR-TEM. Dopants existence and evaluation of elemental constitution Mg, O were corroborated using EDS technique. Catalytic activity against methyl blue ciprofloxacin (MBCF) was significantly reduced (45%) for higher GO dopant concentration (0.05), whereas bactericidal activity of MgO against
E. coli
was improved significantly (4.85 mm inhibition zone) upon doping with higher concentration (0.05) of GO, owing to the formation of nanorods.
Previous research has documented significant associations between the COVID-19 pandemic lockdown, various mental health problems, and coping strategies. However, literature on the moderating role of ...gender on the relationship between distress and coping strategies during COVID-19 is almost nonexistent. Hence, the main objective of this study was two folds. To examine gender differences in distress and coping strategies, and to test the moderating effect of gender on the relationship between distress and coping among university faculty members and students during the COVID-19 pandemic.
A cross-sectional web-based study design was used to collect data from the participants. A sample of 649 participants (68.9% university students and 31.1% faculty members) was selected. The General Health Questionnaire (GHQ-12) and the Coping Inventory for Stressful Situations (CISS) were used to collect data from the participants. The survey was sent out during the COVID-19 lockdown from May 12th to June 30th, 2020.
The results showed significant gender differences in distress and the three coping strategies. Women consistently scored higher on distress (
< 0.01), task-focused (
< 0.05), emotion-focused (
< 0.001), and avoidance coping (
< 0.01) compared to men. Gender moderated the relationship between emotion-focused coping and distress (
< 0.001) but not the relationship between distress and task-focused or avoidance coping.
Increased emotion-focused coping is associated with decreased distress among women while the use of emotion-focused coping by men predicted more distress. Workshops and programs focused on providing skills and techniques on how to cope with stressful situations induced by the COVID-19 pandemic are recommended.
PDF
