This study aims to assess the influence of a rib on the base pressure and the flow development in an abruptly expanded duct at sonic Mach number. Initially, the simulations were done to validate the experimental results, keeping all the parameters the same. Accordingly, a duct-of-area ratio of 6.25 was considered for validation. Five ribs of aspect ratios 3:1, 3:2, and 3:3 were used as a first step, and simulations were performed for the same nozzle pressure ratios. Results indicate that for an area ratio of 6.25, there is a continuous decrease in the base pressure despite the nozzles being highly under-expanded. The lower aspect ratio of the rib tends to reduce the base pressure, whereas a higher aspect ratio effectively increases the base pressure for an area ratio of 6.25. Later simulations considered a single rib instead of five ribs, varying the rib's heights from 1 mm to 5 mm. Results show that the base pressure increases considerably when rib heights are 4 mm and 5 mm. The influence of ribs at two duct diameters (25 mm and 18 mm) is studied to assess the impact of a decrease in the area ratio and, hence, a decrease in the relief available to the flow. Results of duct 18 mm show that passive control becomes very effective when a rib of 3 mm height is located at a 3D position. The differences in the base pressure, velocity, and pressure field for each case are explored. The simulation results indicate that the rib breaks the primary vortex at the base and forms multiple vortices. Turbulent kinetic energy increases in the presence of ribs more than without a rib.
The Sine-Cosine algorithm (SCA) is a population-based metaheuristic algorithm utilizing sine and cosine functions to perform search. To enable the search process, SCA incorporates several search parameters. But sometimes, these parameters make the search in SCA vulnerable to local minima/maxima. To overcome this problem, a new Multi Sine-Cosine algorithm (MSCA) is proposed in this paper. MSCA utilizes multiple swarm clusters to diversify & intensify the search in-order to avoid the local minima/maxima problem. Secondly, during update MSCA also checks for better search clusters that offer convergence to global minima effectively. To assess its performance, we tested the MSCA on unimodal, multimodal and composite benchmark functions taken from the literature. Experimental results reveal that the MSCA is statistically superior with regards to convergence as compared to recent state-of-the-art metaheuristic algorithms, including the original SCA.
Integrating photocatalysis with electrocatalysis may represent a synergistic approach to address environmental and energy challenges. In this context, we explored synthesizing a series of nanocomposite materials using a solid-state approach involving simple grinding and subsequent thermal treatment for the photocatalytic purification of dinoseb and electrocatalytic oxygen evolution (OER). Interestingly, among the series of synthesized materials, 40 wt percentage of 3D/2D/1D:ZnFe2O4/NiAl-LDH/MWCNTs ternary nanocomposite (40-NZM) showed highly improved dinoseb detoxification and OER efficiencies compared to those of pure materials. Importantly, approximately 98% detoxification of dinoseb was observed within 75 min of irradiation time under a visible light source. Remarkably, the 40-NZM nanocomposite exhibited the highest rate constant value (k = 4.1 × 10-2 min-1) with a favorable R2 (0.98) parameter. Furthermore, 40-NZM showed promising electrocatalytic OER performance, requiring only 217 mV of overpotential to achieve 10 mAcm-2 of current density with a smaller Tafel slope of 66.6 mVdec-1. Additionally, long-term stability was tested by recording 2000 cyclic voltammetry (CV) cycles. The results revealed that 40-NZM could maintain its catalytic activity for a longer duration as it required only 227 mV to attain 10 mAcm-2 even after 2000 CV cycles. Consequently, these outstanding characteristics of 40-NZM nanocomposite underscore the significant potential for catalytic water purification and sustainable energy conversion.
COVID-19 led restrictions make it imperative to study how pandemic affects the systemic risk profile of global commodities network. Therefore, we investigate the systemic risk profile of global commodities network as represented by energy and nonenergy commodity markets (precious metals, industrial metals, and agriculture) in pre- and post-crisis period. We use neural network quantile regression approach of Keilbar and Wang (Empir Econ 62:1-26, 2021) using daily data for the period 01 January 2018-27 October 2021. The findings suggest that at the onset of COVID-19, the two firm-specific risk measures namely value at risk and conditional value of risk explode pointing to increasing systemic risk in COVID-19 period. The risk spillover network analysis reveals moderate to high lower tail connectedness of commodities within each sector and low tail connectedness of energy commodities with the other sectors for both pre- and post-COVID-19 periods. The Systemic Network Risk Index reveals an abrupt increase in systemic risk at the start of pandemic, followed by gradual stabilization. We rank commodities in terms of systemic fragility index and observe that in post COVID-19 period, gold, silver, copper, and zinc are the most fragile commodities while wheat and sugar are the least fragile commodities. We use Systemic Hazard Index to rank commodities with respect to their risk contribution to global commodities network. During post COVID-19 period, the energy commodities (except natural gas) contribute most to the systemic risk. Our study has important implications for policymakers and the investment industry.
Conference abstract:
Objectives: To evaluate physician’s knowledge and adherence to asthma guideline adherence (GINA 2011) at emergency department of Hospital Pulau Pinang, Malaysia and to calculate cost of adhered and non-adhered prescriptions
Methods: A cross-sectional survey was conducted to evaluate knowledge of GINA, 2011 asthma guideline at emergency department of Hospital Pulau Pinang, Malaysia. A total of 810 patient prescriptions of 27 doctors (30 prescriptions per doctor) were viewed to asses doctor’s guideline adherence. Patients’ prescriptions were categorised in terms of asthma severity as mild, moderate and severe. Prescriptions were labelled as adhered or non-adhered in terms of doctor treatment according to patient asthma severity as recommended by CPG (GINA 2011). Cost of adhered and non-adhered was calculated according to asthma severity.
Results: Twenty two (81.5%) doctor’s had adequate GINA, 2011 asthma guideline knowledge (Mean 16.7, SD ± 1.5). Six hundred and twenty eight (77.5%) patients received guideline (GINA 2011) adhered pharmacotherapy. Six hundred and seventy eight (83.7%) patients asthma were classified as mild asthma, 128 (15.8%) patients were classified as moderate asthma and 4 (0.5%) patients were classified as severe asthma. Pearson correlation indicated no statistical significant association between asthma guideline adherence and asthma guideline knowledge score (p=0.27). Univariate analysis indicate that patients with age group 25-35 years and with hypertension as co-morbidity received significantly better pharmacotherapy (p=0.04, p=0.03 respectively). Total cost of 628 adhered prescriptions was RM 5792.87 whereas cost of 182 non-adhered prescriptions was RM 1759.09. Cost of single mild asthma adhered prescription (RM 9.18) was less as compared to non adhered mild asthma prescription (RM 10.39).
Conclusions: Emergency doctor’s had adequate GINA, 2011 asthma guideline knowledge. Majority of patients received GINA, 2011 asthma guideline adhered pharmacotherapy. Cost effective medication can significantly reduce socioeconomic burden related to asthma.
The present study examined the predictors of psychological strengths and subjective well-being for dealing with academic stress perceived by university engineering students. Sample of 400 Malaysian (N = 180 boys and N = 220 girls) age varies 18 to 25 years and 400 Indian students (N = 240 boys and N = 160 girls) age varies 18 to 25 years from public universities were participated. Quantitative method was used for data analysis. Findings shows that gender, religiosity and socioeconomic status are significantly influencing psychological strengths and subjective well-being of both Indian and Malaysian students. Findings also revealed that parental involvement and problem solving coping styles were significantly predicting psychological strengths and subjective well-being among both countries participants. Findings of the current study provide the insight for the educators, and parents dealing with adolescents.
Conference abstract:
OBJECTIVES.. To evaluate doctors’ adherence to Malaysian Clinical Practice Guideline (CPG) 2009 in the management of diabetes mellitus with co-morbidities in Malaysia.
METHODS. Cross-sectional study was done at a tertiary-care hospital in Malaysia. Total 51 physicians and 1020 patients’ prescriptions written by same physicians (20 prescriptions per physician) were analyzed. All patients had diabetes mellitus with co-morbidities. Depending on the recommendations of CPG 2009, the prescriptions were clustered as adherent and non-adherent prescriptions. All obtained data were analyzed using descriptive and inferential statistics.
RESULTS. A statistically significant negative association (Ф= 0.094, p-value=0.003) was observed between diabetes mellitus control and co-morbidities. CPG adherent had statistically weak negative association (Ф= - 0.081, p-value=0.010) with patients having co-morbidities (41.6%). No statistically significant association was observed between CPG adherence and any other co-morbidity. Majority of the patients received guidelines-compliant pharmacotherapy. The overall good level of physician adherence with CPG 2009 was observed in the management of diabetes mellitus with co-morbidities.
CONCLUSIONS. The study explored several features of prescription pattern of the physicians involved in the management of diabetes mellitus with co-morbidities and recognized the need for improvement in their prescription pattern for treating the diabetes mellitus.
Thiourea derivatives (1-38) were synthesized and evaluated for their urease inhibition potential. The synthetic compounds showed a varying degree of in vitro urease inhibition with IC50 values 5.53 ± 0.02-91.50 ± 0.08 μM, most of which are superior to the standard thiourea (IC₅₀ = 21.00 ± 0.11 μM). In order to ensure the mode of inhibition of these compounds, the kinetic study of the most active compounds has been carried out. Most of these inhibitors were found to be mixed-type of inhibitors, except compounds 13 and 30 which were competitive, while compound 19 was identified as non-competitive inhibitor with Ki values between 8.6 and 19.29 μM.
1 Increased renal vascular resistance is one renal functional abnormality that contributes to hypertension, and alpha(1)-adrenoceptors play a pivotal role in modulating this renal vascular resistance. This study investigates the functional contribution of alpha(1)-adrenoceptor subtypes in the renal cortical vasculature of Wistar-Kyoto rats on a normal sodium diet (WKYNNa) compared with those given saline to drink for 6 weeks (WKYHNa). 2 The renal cortical vascular responses to the adrenergic agonists noradrenaline (NA), methoxamine (ME) and phenylephrine (PE) were measured in WKYHNa and WKYNNa rats either in the absence (the control phase) or presence of chloroethylclonidine (CEC), an alpha(1B)-adrenoceptor antagonist, 5-methylurapidil (5-MeU), an alpha(1A) antagonist, or BMY7378, an alpha(1D) antagonist. 3 Results showed a greater renal cortical vascular sensitivity to NA, PE and ME in the WKYHNa compared with WKYNNa rats (P < 0.05). Moreover, 5-MeU and BMY7378 attenuated adrenergically induced renal cortical vasoconstriction in WKYHNa and WKYNNa rats; this response was largely blunted in CEC-treated WKYHNa rats (all P < 0.05) but not in CEC-treated WKYNNa rats. 4 The data suggest that irrespective of dietary sodium content, in Wistar-Kyoto rats alpha(1A)- and alpha(1D)-subtypes are the major alpha(1)-adrenoceptors in renal cortical vasculature; however, there appears to be a functional involvement of alpha(1B)-adrenoceptors in the WKYHNa rats.
Syzygium samarangense (Family; Myrtaceae) or 'makopa', as it is commonly known, is native to Malaysia, some islands of Indonesia and to Far East in general. This study was undertaken to rationalize the use of this plant in hypermotility states of the gut. The hexane extract of S. samarangense (Ss.Hex) was found to dose-dependently (10-3000 microg/mL) relax the spontaneously contracting isolated rabbit jejunum. When tested for a possible calcium channel blocking (CCB) activity, the extract (10-1000 microg/mL) relaxed the high K+-induced contractions and also decreased the Ca++ dose-response curves in a dose-dependent manner (30-100 microg/mL), confirming the CCB activity. Four flavonoids isolated from the hexane extract were tested for a possible spasmolytic activity. All flavonoids, identified as: 2'-hydroxy-4',6'-dimethoxy-3'-methylchalcone (SS1), 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (SS2), 2',4'-dihydroxy-6'-methoxy-3'-methylchalcone (SS3) and 7-hydroxy-5-methoxy-6,8-dimethylflavanone (SS4), showed dose-dependent (10-1000 microg/mL) spasmolytic activity with SS2 being the most potent. These results indicate that the presence of compounds with spasmolytic and calcium antagonist activity may be responsible for the medicinal use of the plant in diarrhoea.
This study attempted to clarify the influence of a cross-linker, N,N-methylenebisacrylamide (MBA), and N-isopropylacrylamide (NIPAM) on the non-isothermal kinetic degradation, solid state and lifetime of hydrogels using the Flynn-Wall-Ozawa (F-W-O), Kissinger, and Coats-Redfern (C-Red) methods. The series of dual-responsive Cs-PNIPAM-MBA microgels were synthesized by soapless-emulsion free radical copolymerization in an aqueous medium at 70 °C. The thermal properties were investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under nitrogen atmosphere. The apparent activation energy using the chosen Flynn-Wall-Ozawa and Kissinger methods showed that they fitted each other. Meanwhile, the type of solid state mechanism was determined using the Coats-Redfern method proposed for F1 (pure Cs) and F2 (Cs-PNIPAM-MBA hydrogel series) types, which comprise random nucleation with one nucleus reacting on individual particles, and random nucleation with two nuclei reacting on individual particles, respectively. On average, a higher Ea was attributed to the greater cross-linking density of the Cs hydrogel.
The fluoroquinolone antibacterial drug ciprofloxacin (cip) has been used to cap metallic (silver and gold) nanoparticles by a robust one pot synthetic method under optimized conditions, using NaBH₄ as a mild reducing agent. Metallic nanoparticles (MNPs) showed constancy against variations in pH, table salt (NaCl) solution, and heat. Capping with metal ions (Ag/Au-cip) has significant implications for the solubility, pharmacokinetics and bioavailability of fluoroquinolone molecules. The metallic nanoparticles were characterized by several techniques such as ultraviolet visible spectroscopy (UV), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) methods. The nanoparticles synthesized using silver and gold were subjected to energy dispersive X-ray tests in order to show their metallic composition. The NH moiety of the piperazine group capped the Ag/Au surfaces, as revealed by spectroscopic studies. The synthesized nanoparticles were also assessed for urease inhibition potential. Fascinatingly, both Ag-cip and Au-cip NPs exhibited significant urease enzyme inhibitory potential, with IC50 = 1.181 ± 0.02 µg/mL and 52.55 ± 2.3 µg/mL, compared to ciprofloxacin (IC50 = 82.95 ± 1.62 µg/mL). MNPs also exhibited significant antibacterial activity against selected bacterial strains.