19672 research outputs found
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Serotypes & penicillin susceptibility of Streptococcus pneumoniae isolated from children admitted to a tertiary teaching hospital in Malaysia
No full textBackground & objectives: Streptococcus pneumoniae (pneumococcus) is a highly invasive extracellular pathogen that causes diseases such as pneumonia, otitis media and meningitis. This study was undertaken to determine the serotype diversity and penicillin susceptibility of S. pneumoniae isolated from paediatric patients in a tertiary teaching hospital in Malaysia. Methods: A total of 125 clinical isolates collected from January 2013 to May 2015 were serotyped using seven sequential multiplex polymerase chain reactions. The susceptibility of these isolates to penicillin was also investigated. Results: Serotypes detected among the isolates were serotypes 3, 6A/B, 6C, 11/A/D/F, 15A/F, 19A, 19F, 23A, 23F, 34. Serotypes 19F and 6A/B were the most prevalent serotypes detected. Most of the S. pneumoniae were isolated from nasopharyngeal samples of children below five years of age. Majority of the isolates were penicillin susceptible. Only 5.6 per cent of the isolates were non-susceptible to penicillin, mostly of serotype 19F. Interpretation & conclusions: Our study revealed the distribution of various serotypes in S. pneumoniae isolates obtained from children in a teaching hospital at Kuala Lumpur, Malaysia and decreasing rates of penicillin resistance among them. The shifts in serotypes and susceptibility to penicillin from time to time have been observed. Continuous monitoring and surveillance are pivotal for better infection control and management of pneumococcal infections among children
Inactivation of nuclear factor κB by MIP-based drug combinations augments cell death of breast cancer cells
No full textBackground: Drug combination therapy to treat cancer is a strategic approach to increase successful treatment rate. Optimizing combination regimens is vital to increase therapeutic efficacy with minimal side effects. Materials and methods: In the present study, we evaluated the in vitro cytotoxicity of double and triple combinations consisting of 1′S-1′-acetoxychavicol acetate (ACA), Mycobacterium indicus pranii (MIP) and cisplatin (CDDP) against 14 various human cancer cell lines to address the need for more effective therapy. Our data show synergistic effects in MCF-7 cells treated with MIP:ACA, MIP:CDDP and MIP:ACA:CDDP combinations. The type of interaction between MIP, ACA and CDDP was evaluated based on combination index being <0.8 for synergistic effect. Identifying the mechanism of cell death based on previous studies involved intrinsic apoptosis and nuclear factor kappa B (NF-κB) and tested in Western blot analysis. Inactivation of NF-κB was confirmed by p65 and IκBα, while intrinsic apoptosis pathway activation was confirmed by caspase-9 and Apaf-1 expression. Results: All combinations confirmed intrinsic apoptosis activation and NF-κB inactivation. Conclusion: Double and triple combination regimens that target induction of the same death mechanism with reduced dosage of each drug could potentially be clinically beneficial in reducing dose-related toxicities
Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia: Correlations between clinical, phenotypic, genotypic characteristics and mortality in a tertiary teaching hospital in Malaysia
No full textMethicillin-resistant Staphylococcus aureus (MRSA) bacteremia is a serious infection that can result in significant morbidity and mortality. A retrospective cohort study was conducted to determine the predictors of mortality in patient with MRSA bacteremia correlating with clinical, phenotypic and genotypic characteristics of the relevant strains. Most of the bacteremia cases were healthcare-associated (P < 0.0001). Older age (P < 0.0001) and comorbidities (diabetes mellitus, hypertension and chronic kidney disease) were identified as the risk factors for MRSA bacteremia. All the strains were sensitive to vancomycin. Most MRSA strains causing bacteremia belonged to SCCmec type III-ST239 and exhibited pulsotype H. According to the multivariate analysis, age ≥ 60 years old (P = 0.022), female gender (P = 0.0003), pneumonia (P = 0.011) as source of infection as well as high APACHE II, Charlson comorbidity Index and Pitt's bacteremia scores were significantly associated with patient's mortality. There were emergence of MRSA clones such as SCCmec type I-ST152, SCCmec type V-ST45 and SCCmec type V-ST951 that was discovered for the first time in Malaysia. To our knowledge, this is the first study correlating the clinical, phenotypic and genotypic characteristics of patients with MRSA bacteremia as well as determining the risk factors for mortality in Malaysian hospital
Heat transfer over a steady stretching surface in the presence of suction
No full textThe purpose of this paper is to present the Cattaneo–Christov heat flux model for Maxwell fluid past a stretching surface where the presence of suction/injection is taken into account. The governing system of equations is reduced to the ordinary differential equations with the boundary conditions by similarity transformation. These equations are then solved numerically by two approaches, Haar wavelet quasilinearization method (HWQM) and Runge–Kutta–Gill method (RK Gill). The behavior of various pertinent parameters on velocity and temperature distributions is analyzed and discussed. Comparison of the obtained numerical results is made between both methods and with the existing numerical solutions found in the literature, and reasonable agreement is noted
Tin(IV) oxide nanoparticles as a saturable absorber for a Q-switched erbium-doped fiber laser
No full textWe demonstrate a passively Q-switched erbium-doped fiber laser using a tin(IV) oxide (SnO 2 ) nanoparticle layer as a saturable absorber. A SnO 2 nanoparticle is composited with polyvinyl alcohol (PVA) to form thin saturable absorber film and is sandwiched between fiber ferrules in a ring fiber laser cavity to produce stable, self-started Q-switched laser operation. Q-switched pulsing occurs for pump power between 38 mW and 106 mW. Repetition rate of the laser increases with pump power from 35.4 kHz to 65.6 kHz and the pulse width narrows from 7.64 μs to 2.92 μs. The maximum pulse energy and average output power achieved are 72.11 nJ and 4.73 mW, respectively. Utilizing a tunable bandpass filter, tunable Q-switched laser operation across the C-band (1521 nm-1565 nm) is demonstrated. The laser output is stable across the entire tuning range
An investigation of the dye-sensitized solar cell performance using graphene-titania (TrGO) photoanode with conventional dye and natural green chlorophyll dye
No full textDevelopment of innovative low-cost and efficient DSSCs (dye-sensitized solar cell) device for solar energy conversion is essential. In this present study, the performance of DSSCs based on graphene-titania (TrGO) photoanode using conventional N719 (synthetic dye) and natural green chlorophyll dye (organic dye) were extensively studied, analysed and discussed. TrGO was successfully synthesized via one step sol precipitation peptization technique using titanium (IV) isopropoxide (TTIP) and reduced graphene oxide (rGO) as starting materials. It was found that TrGO-2 exhibited the highest photocurrent generation among samples regardless of dye type. DSSCs device fabricated using N719 dye showed 9.15 mA cm−2 of photocurrent with 3.95% efficiency whereas DSSCs device using natural chlorophyll green dye exhibited photocurrent density of 3.43 mA cm−2 with 0.67% efficiency. From the Tauc plot, band gap was narrowed from 3.17 eV of TiO2 to 2.78 eV of TrGO considering the graphene extended the absorption range of the film to the visible light region. The main reason was associated with the better surface contact of the TiO2 dopants with the rGO film resulting in a lower charge transfer resistance
Meeting the demands of a multi-dimensional professional writing course for tertiary students
Get PDFWhat distinguishes English for Specific Purpose (ESP) from General English (GE) is not the existence of a need but the awareness of it (Hutchinson & Waters, 1987). And thus, in designing a compulsory English course for advanced users of English (CEFR B2/Low C1), the Faculty of Languages & Linguistics, University of Malaya (a Malaysian public university) faces the challenge of meeting the multi-dimensional demands of a holistic ESP course. Hence, this paper concerns how we have aligned the course design of an advanced professional writing course for tertiary students with the various institutional demands to equip undergraduates with employable skills particularly writing skills for the workplace. We also evaluate the course feedback received over 3 semesters to gauge the achievement of the intended learning outcomes
Influence of calcination on the morphology and crystallinity of titanium dioxide nanofibers towards enhancing photocatalytic dye degradation
No full textThe development of titanium dioxide (TiO2) nanostructures with superior morphology and crystallinity is crucial for the photocatalytic degradation of textile dyes. This study highlights the evolution in the morphology and crystallinity of electrospun TiO2 nanofibers using polyvinylpyrrolidone (PVP) support in relation to applied calcination temperature, and their influence towards the photocatalytic dye degradation performance of the material. Results showed distinct differences in the thermal decomposition patterns of (PVP) on the fiber surface and the inner core, where it is dependent on the presence of oxygen. These differences drastically affect the morphology of the obtained fibers especially its surface area and porosity. Crystallinity of the embedded TiO2 particles increases with higher calcination temperature which contributes to higher photocatalytic performance. Highly mesoporous nanofibers with crystalline anatase TiO2 particles, together with fiber diameter of 118.3 ± 6.30 nm and surface area of 72.3219 m2 g-1 are obtained at 500 °C. The combination of these properties produced the best photocatalytic dye degradation rate constant of 0.080 29 min-1 and 0.0543 min-1 for methylene blue and methyl orange respectively. The performance can be attributed to a combination of high particle crystallinity and fiber porosity and surface area
A Performance Study of Controlled Impact Timing on Harmonics Reduction in Operational Modal Testing
No full textAs an alternative to operational modal analysis and classical experimental modal analysis (EMA), a novel method was introduced previously, namely impact-synchronous modal analysis (ISMA). The effectiveness ISMA on rotor and structural dynamic systems has been proven in previous literature. More recently, an automated impact device (AID) was introduced which utilized tachometer pulse as initiation signal and its effectiveness on ISMA was proven. An attempt to further enhance this device in term of equipment and cost is then proposed by replacing the tachometer with the in-use tri-axial accelerometer through utilizing the filtered response of cyclic load component as an initiation signal to control the impact device, which is also the primary aim for this study. Prior to modal testing, accuracy of this device is illustrated at desired phase angles of 0 deg, 90 deg, 180 deg, and 270 deg. Subsequently, frequency response function (FRF) estimations obtained for ISMA using enhanced AID has demonstrated the suppression capabilities of this device on disturbances, i.e., reduction of 93.58% at 30 Hz and 57.78% at 60 Hz, resulting in a high correlation for signature assurance criterion (SAC) and cross signature assurance criterion (CSAC). Modal parameters extracted from the EMA and ISMA using impact device are presented and compared, for the first three natural modes of the test rig. It is found that natural frequencies are deviating by less than 6%, whereas modal assurance criterion (MAC) values between the mode shapes of the two tests are found to be above 0.9
Wear characteristics of patterned and un-patterned tetrahedral amorphous carbon film in the presence of synthetic and bio based lubricants
No full textIn this article, wear performance of patterned and non-patterned tetrahedral carbon thin film (ta-C) is compared in the presence of various lubricants. For this purpose, wear tests were conducted at temperatures (40 °C-125 °C) which are normally found during automotive engine operation. Wear test were conducted at 100 N load and 120 min. The results showed that bio-based lubricant show better wear performance at 40 and 80 °C compared to PAO lubricant for both laser patterned and non-patterned ta-C thin film. However, at the temperature of 125 °C, PAO showed better wear performance than palm based TMP ester. This can be because of unstable film formation at higher temperatures in case of bio-based lubricant. It was also found that patterned ta-C thin films shows higher wear resistance than non-patterned thin film. This can be because of micro pores which can provide lubricant, capture micro and nano wear particle and behave as micro hydrodynamic bearings