Synthesis of Aluminum Hydroxide Nanoparticles in Spontaneously Generated Vesicles

Unilamellar vesicles, formed spontaneously by mixing single-tailed cationic (cetyl trimethyl ammonium tosylate, CTAT) and anionic aqueous solutions of (sodium dodecyl benzene sulfonate, SDBS) surfactants have been used as reactors for the aqueous phase precipitation of nanometer sized particles within their inner cores. AlCl3 solution was encapsulated within these vesicles, aluminum ions were replaced with sodium ions in the extravesicular phase, and sodium hydroxide was then added to the extravesicular region. Hydroxyl ions penetrate through the vesicle walls and react with the available aluminum in the intravesicular region to form the product. The morphology and sizes of these particles were examined by transmission electron microscopy, while their phase and crystalline nature were probed by electron and x-ray diffraction. The product particles were nanometer-sized with near spherical morphology. Good control of particle size was achieved by varying the initial concentration of electrolyte. Single particle electron diffraction revealed a symmetric pair of spots, indicating that the particles were either single crystals or polycrystalline with á low number of grain boundaries or defects. Although wide area electron diffraction showed that the product was δ–Al2O3, powder x-ray diffraction revealed that these particles were, in fact, Al(OH)3. It is likely that heating of these nanoparticles by the high energy electron beam in a high vacuum environment causes a phase transformation, resulting in the difference between the electron and x-ray diffraction results. These results represent the first demonstration of precipitation within vesicles produced spontaneously by mixing appropriate ratios of inexpensive single-tailed surfactants, and may potentially make intravesicular precipitation a commercially viable route for making nanometer-sized particles

Synthesis and Antibacterial Activity of Thiophenes

2-[Bis(methylthio)methylene]propanedinitrile 1a reacted in one-pot successively with piperidine, sodium sulfide, chloroacetonitrile, and potassium carbonate to afford 3-amino-5-(1-piperidinyl)-2,4-thiophenedicarbonitrile 2a. Similar reaction using the last three reagents with ethyl 2-cyano-3,3-bis(methylthio)acrylate 1b produced ethyl 4-amino-5-cyano-2-(methylthio)thiophene-3-carboxylate 2b. The synthesized compounds were characterized by using FT-IR, 1H-NMR, 13C-NMR, and mass spectral data. Antibacterial activities of the synthesized compounds are also reported

Ultrasonic transducer tuning using wafer bonding method

This study demonstrates the wafer bonding method for performance tuning of piezoelectric Micromachined Ultrasonic Transducer (pMUT) from on-the-shelf piezoelectric disc (PZT). Polydimethylsiloxane (PDMS) and Epoxy were studied as adhesive materials. A thick bonding layer was deposited using the spin coating technique. Wafer bonding was carried out at room temperature to simulate in-situ pMUT repairing scenario. Bonding integrity is analyzed using Field Emission Scanning Electron Microscope (FESEM) images, while electrical characterization of pMUT is carried out using impedance analysis. Fabricated pMUTs have been calibrated using the pulse-echo technique in a freshwater tank. This study found that PDMS at the minimum thickness of 28 µm is preferably compatible for in-situ wafer bonding of pMUT compared to the Epoxy. PDMS has significantly reduced device impedance at 62.4 % reduction compared to 58.9 % reduction for Epoxy. Both pMUTs were able to transmit and receive short acoustic ping with the calibrated speed of sound of 1333.3 m/s. PDMS has successfully contributed to a broader operating frequency between 30 – 150 kHz for transmission and 75 – 140 kHz for the reception

Ultrasonic transducer tuning using wafer bonding method

954-959This study demonstrates the wafer bonding method for performance tuning of piezoelectric Micromachined Ultrasonic Transducer (pMUT) from on-the-shelf piezoelectric disc (PZT). Polydimethylsiloxane (PDMS) and Epoxy were studied as adhesive materials. A thick bonding layer was deposited using the spin coating technique. Wafer bonding was carried out at room temperature to simulate in-situ pMUT repairing scenario. Bonding integrity is analyzed using Field Emission Scanning Electron Microscope (FESEM) images, while electrical characterization of pMUT is carried out using impedance analysis. Fabricated pMUTs have been calibrated using the pulse-echo technique in a freshwater tank. This study found that PDMS at the minimum thickness of 28 μm is preferably compatible for in-situ wafer bonding of pMUT compared to the Epoxy. PDMS has significantly reduced device impedance at 62.4 % reduction compared to 58.9 % reduction for Epoxy. Both pMUTs were able to transmit and receive short acoustic ping with the calibrated speed of sound of 1333.3 m/s. PDMS has successfully contributed to a broader operating frequency between 30 – 150 kHz for transmission and 75 – 140 kHz for the reception

Prevalence of Sickness Absence and Its Sociodemographic and Occupational Factors in a Public Service Organization

Sickness absence in any particular organization has negative impacts mainly toward economic, morale and productivity. The purpose of this survey is to determine the prevalence of sickness absence among employees in a government office in a central region of Malaysia to get profiling of the employees taking medical leaves, tocompare the frequency of sickness absence among the employees based on gender, age group and designation and to determine the perception of sickness absence among the employees in relation to their occupation. A cross-sectional study was carried out among 587 workers in the first half of 2017. Data was collected based on Sickness Absence Surveillance form, which was filled by any employee who took medical leave. Other variables such as demographic data, work characteristics and personal health were also included. Subsequently, data entry and analysis were done using SPSS Version 22.0. The overall prevalence rate was 63.0 percent (female = 42.6%, male 20.3%) that includes repeated medical certificate (MC)-taker. Reasons for sickness absence are varied like fever, URTI, pregnancy related, injury, diarrhea, clinic follow-up and many more. Results also showed that sickness absenteeism was higher among female, mainly middle managerial level, presently or previously married, aged from 30 to 39, employed in the organization for over 10 years with no background of chronic medical illness. Therefore, the prevalence of sickness absence among employees in a government office in a central region of Malaysia and factors associated with it are determined. It is recommended for continuation of surveillance simultaneously to have an intervention program in order to find the root cause of sickness absence and thus reducing sickness absence rate. Keywords: sickness absenteeism, surveillance, sociodemographic factors, occupational factor

Commuting Accidents among Health Care Workers Working in Malaysia Government Hospitals

Commuting accidents are accidents occurring while travelling to and from work, and in the course of work. Studies have demonstrated that long working hours are associated with deprived sleeping time. Acute sleep deprivation may result in significant changes in cognitive functioning, alteration of mental status resembling depression or anxiety and difficulty with short-term memory. Some other studies have found that sleep deprivation significantly affects physician performance, alertness and patient safety. However, individual factors concerning workers’ behavior, family-related factors (parenting responsibility), work burden, workplace support as well as environmental factors such as bad weather and bad road conditions are also significant contributors of commuting accidents. The aim of this study is to investigate the relationship of long working hours or odd working hours and the risk exposure of the drivers during their work-commuting trips. The study was based on data collected from official notification forms. Sample size for this research was 554 based on 2014 to 2017 reported cases. Review of the statistics showed that most of the commuting accident causalitiesoccurred during travel to work (30.1%), compared to back from work after normal office hours (28.7%) and during odd hours (night shift and post-call) (12.5%). Nurses contributed significantly to these causalities (53%), followed by hospital attendants (17%), medical officer and assistant medical officer, respectively, 6 percent. Theincreasing number of commuting accidents among healthcare workers is alarming. As such, it is timely that proactive actions be taken by employers to educate their employees, their most valuable assets, on safe commuting management. Keywords: commuting accident, healthcare workers, road crashe

A three-electrode integrated photo-supercapacitor utilizing graphene-based intermediate bifunctional electrode

A dye-sensitized solar cell (DSSC) employing a compact and mesoporous titania (TiO2) film as the anode was integrated with a symmetrical supercapacitor utilizing polypyrrole/reduced graphene oxide (PPy/rGO) electrodes to form a photo-supercapacitor. The double-sided-electrodeposited PPy/rGO material served as an intermediate electrode which was bifunctional in nature; acting as a counter electrode for the DSSC to permit electrolyte regeneration, and also as an electrode for the supercapacitor. The isolated DSSC and supercapacitor were characterized before the integration, and the power conversion efficiency (PCE) of the DSSC was 2.4%, while the specific capacitance of the supercapacitor was 308.1 F/g. The performance of the integrated photo-supercapacitor was tested under a light illumination of 100 mW/cm2. By using a single PPy/rGO electrode at the cell/supercapacitor interface, an extended lifetime was achieved with up to 50 charge/discharge cycles. The photo-supercapacitor possessed a specific capacitance of 124.7 F g−1, and a retention percentage of 70.9% was obtained after 50 consecutive charge/discharge cycles

Wear behaviour at 600°C of surface engineered low-alloy steel containing TiC particles

The work aimed to develop surfaces that could resist wear at high temperatures, thus achieving a prolonged component life. Surface modification of a low-alloy steel by incorporating TiC particles has been undertaken by melting the surface using a tungsten inert gas torch. The dry sliding wear behaviour at 600°C of the original and modified surfaces was compared. Microscopic examination of both surfaces showed glazed layers across the wear tracks, with differing amounts of oxide and homogeneity. Extensive wear occurred on the steel surface, which showed deformation of the wear scar tracks and a steadily increased friction coefficient. The TiC addition reduced the wear loss, coinciding with a glazed layer 33% thinner than that on the low-alloy steel sample

Lipopolysaccharide-induced memory impairment in rats: a model of Alzheimer’s disease

Alzheimer’s disease (AD) is a primary cause of dementia in the middle-aged and elderly worldwide. Animal models for AD are widely used to study the disease mechanisms as well as to test potential therapeutic agents for disease modification. Among the non-genetically manipulated neuroinflammation models for AD, lipopolysaccharide (LPS)-induced animal model is commonly used. This review paper aims to discuss the possible factors that influence rats’ response following LPS injection. Factors such as dose of LPS, route of administration, nature and duration of exposure as well as age and gender of animal used should be taken into account when designing a study using LPS-induced memory impairment as model for AD