In this research,activated carbon from mangosteen peel has been synthesized using sulfuric acid as an activator.The adsorption performance of the activated carbon was optimized using malachite green dye as absorbate.M...In this research,activated carbon from mangosteen peel has been synthesized using sulfuric acid as an activator.The adsorption performance of the activated carbon was optimized using malachite green dye as absorbate.Mala-chite green dye waste is a toxic and non-biodegradable material that damages the environment.Optimization of adsorption processes was carried out using Response Surface Methodology(RSM)with a Box-Behnken Design(BBD).The synthesized activated carbon was characterized using FTIR and SEM instruments.The FTIR spectra confirmed the presence of a sulfonate group(-SO_(3)H)in the activated carbon,indicating that the activation pro-cess using sulfuric acid was successful.SEM characterization shows that activated carbon has porous morphology.Optimization was carried out for three adsorption parameters,namely contact time(20,60,and 120 min),adsor-bent mass(0.005,0.025,and 0.05 g),and initial concentration of malachite green solution(5,50,and 100 mg·L^(-1)).The concentration of the malachite green solution was determined using a UV-Vis spectrophotometer at the max-imum wavelength of malachite green,618 nm.The optimum of malachite green adsorption using mangosteen peel activated carbon was obtained at a contact time of 80 min,an adsorbent mass of 0.032 g,and malachite green initial concentration of 25 mg·L^(-1),with a maximum removal percentage and maximum adsorption capacity of 93.66%and 19.345 mg·g^(-1),respectively.展开更多
Silver nanoparticles(AgNPs)synthesized using tartaric acid as a capping agent have a great impact on the reaction kinetics and contribute significantly to the stability of AgNPs.The protective layer formed by tartaric...Silver nanoparticles(AgNPs)synthesized using tartaric acid as a capping agent have a great impact on the reaction kinetics and contribute significantly to the stability of AgNPs.The protective layer formed by tartaric acid is an important factor that protects the silver surface and reduces potential cytotoxicity problems.These attributes are critical for assessing the compatibility of AgNPs with biological systems and making them suitable for drug delivery applications.The aim of this research is to conduct a comprehensive study of the effect of tartaric acid concentration,sonication time and temperature on the formation of silver nanoparticles.Using Response Surface Methodology(RSM)with Face-Centered Central Composite Design(FCCD),the optimization process identifies the most favorable synthesis conditions.UV-Vis spectrum regression analysis shows that AgNPs stabilized with tartaric acid are more stable than AgNPs without tartaric acid.This highlights the increased stability that tartaric acid provides in AgNP ssssynthesis.Particle size distribution analysis showed a multimodal distribution for AgNPs with tartaric acid and showed the smallest size peak with an average size of 20.53 nm.The second peak with increasing intensity shows a dominant average size of 108.8 nm accompanied by one standard deviation of 4.225 nm and a zeta potential of−11.08 mV.In contrast,AgNPs synthesized with polyvinylpyrrolidone(PVP)showed a unimodal particle distribution with an average particle size of 81.62 nm and a zeta potential of−2.96 mV.The more negative zeta potential of AgNP-tartaric acid indicates its increased stability.Evaluation of antibacterial activity showed that AgNPs stabilized with tartaric acid showed better performance against E.coli and B.subtilis bacteria compared with AgNPs-PVP.In summary,this study highlights the potential of tartaric acid in AgNP synthesis and suggests an avenue for the development of stable AgNPs with versatile applications.展开更多
The adsorption of Pb(II)on silica gel synthesized from chemical glass bottle waste has been studied.The effect of independent variables(adsorbent dose,initial concentration of Pb(II),contact time,and pH)on the Pb(II)r...The adsorption of Pb(II)on silica gel synthesized from chemical glass bottle waste has been studied.The effect of independent variables(adsorbent dose,initial concentration of Pb(II),contact time,and pH)on the Pb(II)removal from water was evaluated and optimized using the Response Surface Methodology(RSM).Under optimized conditions(adsorbent dose:20 mg;contact time:30 min;initial Pb(II)concentration:120 mg.L^(−1);and pH:8),the removal of Pb(II)was 99.77%.The adsorption equilibrium data obtained from the batch experiment were investigated using different isotherm models.The Langmuir isotherm model fits the experimental data.This shows that the surface of the silica gel synthesized from chemical bottles waste was covered by a Pb(II)monolayer.XRF analysis showed that the synthesized silica gel had a SiO_(2) content of 75.63%.Amorphous silica was observed from XRD analysis.SEM-EDX characterization showed that Pb was adsorbed on the silica gel surface.SEM analysis showed that silica gel has irregular particles with a surface area of 297.08 m2.g^(−1) with a pore radius of 15.74 nm calculated from BET analysis.展开更多
This research focuses on the effective removal of methylene blue dye using silica gel synthesized from chemical glass bottle waste as an environmentally friendly and cost-effective adsorbent.The adsorption process was...This research focuses on the effective removal of methylene blue dye using silica gel synthesized from chemical glass bottle waste as an environmentally friendly and cost-effective adsorbent.The adsorption process was optimized using Box-Behnken Design(BBD)and Response Surface Methodology(RSM)to investigate the influence of pH(6;8 and 10),contact time(15;30 and 45 min),adsorbent mass(30;50 and 70 mg),and initial concentration(20;50 and 80 mg/L)of the adsorbate on the adsorption efficiency.The BBD was conducted using Google Colaboratory software,which encompassed 27 experiments with randomly assigned combinations.The silica gel synthesized from chemical glass bottle was characterized by XRD,FTIR,SEM-EDX and TEM.The adsorption result was measured by spectrophotometer UV-Vis.The optimized conditions resulted in a remarkable methylene blue removal efficiency of 99.41%.Characterization of the silica gel demonstrated amorphous morphology and prominent absorption bands characteristic of silica.The Langmuir isotherm model best described the adsorption behavior,revealing chemisorption with a monolayer coverage of methylene blue on the adsorbent surface,and a maximum adsorption capacity of 82.02 mg/g.Additionally,the pseudo-second-order kinetics model indicated a chemisorption mechanism during the adsorption process.The findings highlight the potential of silica gel from chemical glass bottle waste as a promising adsorbent for wastewater treatment,offering economic and environmental benefits.Further investigations can explore its scalability,regenerability,and reusability for industrial-scale applications.展开更多
Dyes are pervasive contaminants in wastewater,posing significant health risks to both humans and animals.Among the various methods employed for effective dye removal,adsorption has emerged as a highly promising approa...Dyes are pervasive contaminants in wastewater,posing significant health risks to both humans and animals.Among the various methods employed for effective dye removal,adsorption has emerged as a highly promising approach due to its notable advantages,including high efficiency,cost-effectiveness,low energy consumption,and operational simplicity compared to alternative treatments.This comprehensive review focuses on investigating adsorbents derived from biowastes and biomass,specifically carbon-based and non-conventional adsorbents,for the removal of malachite green,a widely used dye known for its toxic and carcinogenic properties.Carbon-based adsorbents encompass two main types:activated carbon and biochar,while non-conventional adsorbents refer to powder sorbents without carbonaceous treatments.Extensive studies have reported remarkable findings,with achieved maximum removal percentages exceeding 98%and capacities reaching 250 mg/g.These results highlight the exceptional efficacy of the reviewed adsorbents in eliminating malachite green from wastewater.By exploring the potential of bio-based adsorbents,this review sheds light on sustainable and environmentally friendly solutions for mitigating dye pollution.展开更多
Smartphone ownership among adolescents is getting common in this decade especially in Malaysia;Adolescent are strongly devoted to their smartphone and this may lead to smartphone addiction.Studies have reported that s...Smartphone ownership among adolescents is getting common in this decade especially in Malaysia;Adolescent are strongly devoted to their smartphone and this may lead to smartphone addiction.Studies have reported that smartphone addiction has become an emerging social and health problem especially among the youth in many countries however there is lack of study among adolescents in Malaysia.This study aimed to examine the prevalence and factors associated with smartphone addiction among adolescents in Malaysia.This was a cross-sectional study involving adolescents from 15 primary care clinics throughout the country.Respondents were assessed on their smartphone activities using the Malaysian short version of the Smartphone addiction scale(SAS-M-SV).Multiple logistic regression was used to determine the predictors of smartphone addiction among adolescents.The study was conducted among 921 adolescents with 49.6%male(n=457).The mean age of adolescents was 16.4±2.4 years.The ethnicity distribution were 74.6%Malay,7.3%Chinese,4.7%Indian and 13.4%other ethnicities.The prevalence of smartphone addiction was 37.1%(342/921);37.4%in male and 36.9%in female.Based on multiple logistic regression analysis,longer duration of smartphone use per week was associated with higher odds of smartphone addiction among adolescent(odd ratio=1.005%,95%confidence interval=1.000–1.009,p-value=0.039).Smartphone addiction is present in nearly four in ten adolescents in Malaysia.Adolescents who spend longer duration in smartphone usage per week were associated with higher odds of having smartphone addiction.Parents should be more alert and vigilant about this finding.Hence,parents should limit their children from spending too much of time with smartphone in order to prevent their children from getting smartphone addiction.展开更多
The paper examines the propagation direction and velocity of large-scale traveling ionospheric disturbances （LST1Ds） during extreme geomagnetic storms in the 23rd solar cycle （e.g., October 2003 and November 2003 s...The paper examines the propagation direction and velocity of large-scale traveling ionospheric disturbances （LST1Ds） during extreme geomagnetic storms in the 23rd solar cycle （e.g., October 2003 and November 2003 storms） using GPS observations. In the analysis, the time delay between the vertical total electron content （VTEC） structures at Scott Base, McMurdo, Davis and Casey GPS stations and the distance between these stations were the main parameters in the determination of LSTIDs propagation speed and direction. The observations during October and November 2003 storms show obvious time delay between the total electron content （TEC） enhancement signatures at these stations. The time delay suggests a movement of the ionospheric disturbances from higher to lower latitudes during the October storm with a velocity of 800-1 200 m/s and poleward propagation of LSTIDs during the November storm with a ve- locity of 300-400 m/s. The equatorward or poleward expansion of LSTIDs during the October and November 2003 storms is probably caused by the disturbances of the neutral temperature occurring close to the dayside convection throat or by the neutral wind oscillation induced by atmospheric gravity waves （AGW） launched from the aurora region.展开更多
In the information-oriented society, there are increasing needs to conduct data communication with nearby devices/people. In this light, vibration-based communication method was proposed as one of possible communicati...In the information-oriented society, there are increasing needs to conduct data communication with nearby devices/people. In this light, vibration-based communication method was proposed as one of possible communication means between adjacent devices. This method has been expected to provide an intuitive and safe communication by propagating vibration to a receiver device. This study proposes two types of techniques, which are multi-step ASK (Amplitude Shift Keying) with pseudo clock and PPM (Pulse Position Modulation), to achieve a stable vibration-based communication simply using smart device functions. These proposed techniques are then evaluated through some experiments using several types of smart devices. In addition, the effectiveness of the proposed methods is discussed based on the experimental results.展开更多
Water-Soluble Chitosan(WSC)has been sucessfuly synthesized from squid pens waste.The synthesis of chitosan from chitin was carried out by optimization of deacetylation temperature and time.Chitin was obtained from squ...Water-Soluble Chitosan(WSC)has been sucessfuly synthesized from squid pens waste.The synthesis of chitosan from chitin was carried out by optimization of deacetylation temperature and time.Chitin was obtained from squid pens waste by demineralization and deproteinization process.HCl 7%was used for demineralization and NaOH 10%at 60℃ was applied for deproteinization process.Deacetylation reaction was carried out at varied temperatures i.e.,60℃,70℃,80℃,90℃ and 100℃ in NaOH 50%solution for 10 hours.Deacetylation reaction time were varied for 2 hours,4 hours,6 hours,8 hours,and 10 hours.The crude chitosan obtained then reacted with H2O230%to depolymerize.The synthesis product obtained then characterized by FTIR.The result of squid chitin yield was 33.9%.The optimum temperature and time of chitosan deacetylation process were 90℃ for 8 hours as indicated by the value of deacetylation degree(DD)that equal to 83.94%at optimum temperature and 82.22%at optimum reaction time.The percentage of WSC yield at optimum temperature(90℃)and optimum time(8 hours)were 27.59%and 23.16%,respectively.WSC solubility test was done in water and HCl 0,1N.The solubility of 2.8325 mg/mL and 0.8125 mg/mL were obtained in acid medium and water medium,respectively.展开更多
Biodiesel is a fossil fuel that is in demand to be developed because it is bio-renewable,biodegradable and environmentally friendly.Biodiesel produced from the transesterification reaction of vege Tab.oil using a base...Biodiesel is a fossil fuel that is in demand to be developed because it is bio-renewable,biodegradable and environmentally friendly.Biodiesel produced from the transesterification reaction of vege Tab.oil using a base catalyst.CaO is the most developed catalyst for the reaction of transesterification of oil into biodiesel because it is cheap,the process is easy and has a high level of alkalinity.CaO is a cheap catalyst because it is easily obtained from natural ingredients.The use of CaO catalysts in the reaction formation of biodiesel continues to develop through modification with various porous materials and different oxide materials.In this paper,we discuss the development of CaO,the modification of CaO with a porous material and metal oxide,the mechanism of reaction of CaO and the kinetics of reactions that occur in the reaction transesterification of oil to biodiesel.展开更多
In this paper,we present a three-compartment of pharmacokinetics model with irreversible rate constants.The compartment consists of arterial blood,tissues and venous blood.Fick’s principle and the law of mass action ...In this paper,we present a three-compartment of pharmacokinetics model with irreversible rate constants.The compartment consists of arterial blood,tissues and venous blood.Fick’s principle and the law of mass action were used to develop the model based on the diffusion process.The model is modified into a fractional pharmacokinetics model with the sense of Caputo derivative.The existence and uniqueness of the model are investigated and the positivity of the model is established.The behaviour of the model is investigated by implementing numerical algorithms for the numerical solution of the system of fractional differential equations.MATLAB software is used to plot the graphs for illustrating the variation of drug concentration concerning time.Therefore,the numerical simulations of the model are presented for different values ofαwhich verified the theoretical analysis.Besides,we also observed the pattern of the simulations at the three-compartment of the model by using different values of initial conditions.展开更多
Capsule shells have been successfully fabricated from water-soluble chitosan(WSC)with the addition of alginate and Gembili starch.WSC was synthesized from crab shell chitosan by depolymerization reaction.The capsule s...Capsule shells have been successfully fabricated from water-soluble chitosan(WSC)with the addition of alginate and Gembili starch.WSC was synthesized from crab shell chitosan by depolymerization reaction.The capsule shells were made with the composition of WSC:Alginate,2:1,3:1 and 4:1(w/w)with and without the addition of Gembili starch.Gembili starch was added with a ratio of Alginate:Starch,1:1(w/w).The capsule shell properties were evaluated according to Indonesian Pharmacopoeia standard.The solubility test showed that the capsule shells were comply with the standard.The highest degrees of swelling in water and HCl 0.1 N solution were 491.93%and 410.51%,respectively.The highest degradation percentages in water and HCl 0.1 N solution were 57.80%and 21.44%,respectively.The observation of physical appearance indicated that the capsule shell with WSC:Alginate:Starch in ratio of 3:1:1 has appearance close to commercial capsule shell.展开更多
Many initial value problems are difficult to be solved using ordinary,explicit step-by-step methods because most of these problems are considered stiff.Certain implicit methods,however,are capable of solving stiff ord...Many initial value problems are difficult to be solved using ordinary,explicit step-by-step methods because most of these problems are considered stiff.Certain implicit methods,however,are capable of solving stiff ordinary differential equations(ODEs)usually found in most applied problems.This study aims to develop a new numerical method,namely the high order variable step variable order block backward differentiation formula(VSVOHOBBDF)for the main purpose of approximating the solutions of third order ODEs.The computational work of the VSVO-HOBBDF method was carried out using the strategy of varying the step size and order in a single code.The order of the proposed method was then discussed in detail.The advancement of this strategy is intended to enhance the efficiency of the proposed method to approximate solutions effectively.In order to confirm the efficiency of the VSVO-HOBBDF method over the two ODE solvers in MATLAB,particularly ode15s and ode23s,a numerical experiment was conducted on a set of stiff problems.The numerical results prove that for this particular set of problem,the use of the proposed method is more efficient than the comparable methods.VSVO-HOBBDF method is thus recommended as a reliable alternative solver for the third order ODEs.展开更多
This study investigates the recent extreme temperature trends across 19 stations in the Klang Valley, Malaysia, over the period 2006^-16. Fourteen extreme index trends were analyzed using the Mann-Kendall non-parametr...This study investigates the recent extreme temperature trends across 19 stations in the Klang Valley, Malaysia, over the period 2006^-16. Fourteen extreme index trends were analyzed using the Mann-Kendall non-parametric test, with Sen’s slope as a magnitude estimator. Generally, the annual daily mean temperature, daily mean maximum temperature, and daily mean minimum temperature in the Klang Valley increased significantly, by 0.07°C yr^-1, 0.07°C yr^-1 and 0.08°C yr^-1, respectively. For the warm temperature indices, the results indicated a significant upward trend for the annual maximum of maximum temperature, by 0.09°C yr^-1, and the annual maximum of minimum temperature, by 0.11°C yr^-1. The results for the total number of warm days and warm nights showed significant increasing trends of 5.02 d yr^-1 and 6.92 d yr^-1, respectively. For the cold temperature indices, there were upward trends for the annual minimum of maximum temperature, by 0.09°C yr^-1, and the annual minimum of minimum temperature, by 0.03°C yr^-1, concurrent with the decreases in the total number cold days (TX10P), with -3.80 d yr^-1, and cold nights (TN10P), with -4.33 d yr^-1. The 34°C and 37°C summer days results showed significant upward trends of 4.10 d yr^-1 and 0.25 d yr^-1, respectively. Overall, these findings showed upward warming trends in the Klang Valley, with the minimum temperature rate increasing more than that of the maximum temperature, especially in urban areas.展开更多
文摘In this research,activated carbon from mangosteen peel has been synthesized using sulfuric acid as an activator.The adsorption performance of the activated carbon was optimized using malachite green dye as absorbate.Mala-chite green dye waste is a toxic and non-biodegradable material that damages the environment.Optimization of adsorption processes was carried out using Response Surface Methodology(RSM)with a Box-Behnken Design(BBD).The synthesized activated carbon was characterized using FTIR and SEM instruments.The FTIR spectra confirmed the presence of a sulfonate group(-SO_(3)H)in the activated carbon,indicating that the activation pro-cess using sulfuric acid was successful.SEM characterization shows that activated carbon has porous morphology.Optimization was carried out for three adsorption parameters,namely contact time(20,60,and 120 min),adsor-bent mass(0.005,0.025,and 0.05 g),and initial concentration of malachite green solution(5,50,and 100 mg·L^(-1)).The concentration of the malachite green solution was determined using a UV-Vis spectrophotometer at the max-imum wavelength of malachite green,618 nm.The optimum of malachite green adsorption using mangosteen peel activated carbon was obtained at a contact time of 80 min,an adsorbent mass of 0.032 g,and malachite green initial concentration of 25 mg·L^(-1),with a maximum removal percentage and maximum adsorption capacity of 93.66%and 19.345 mg·g^(-1),respectively.
基金funded by the Directorate of Research and Community Service (DRPM,Direktorat Riset dan Pengabdian Kepada Masyarakat)ITS through the ITS Research Local Grant (No:1665/PKS/ITS/2023).
文摘Silver nanoparticles(AgNPs)synthesized using tartaric acid as a capping agent have a great impact on the reaction kinetics and contribute significantly to the stability of AgNPs.The protective layer formed by tartaric acid is an important factor that protects the silver surface and reduces potential cytotoxicity problems.These attributes are critical for assessing the compatibility of AgNPs with biological systems and making them suitable for drug delivery applications.The aim of this research is to conduct a comprehensive study of the effect of tartaric acid concentration,sonication time and temperature on the formation of silver nanoparticles.Using Response Surface Methodology(RSM)with Face-Centered Central Composite Design(FCCD),the optimization process identifies the most favorable synthesis conditions.UV-Vis spectrum regression analysis shows that AgNPs stabilized with tartaric acid are more stable than AgNPs without tartaric acid.This highlights the increased stability that tartaric acid provides in AgNP ssssynthesis.Particle size distribution analysis showed a multimodal distribution for AgNPs with tartaric acid and showed the smallest size peak with an average size of 20.53 nm.The second peak with increasing intensity shows a dominant average size of 108.8 nm accompanied by one standard deviation of 4.225 nm and a zeta potential of−11.08 mV.In contrast,AgNPs synthesized with polyvinylpyrrolidone(PVP)showed a unimodal particle distribution with an average particle size of 81.62 nm and a zeta potential of−2.96 mV.The more negative zeta potential of AgNP-tartaric acid indicates its increased stability.Evaluation of antibacterial activity showed that AgNPs stabilized with tartaric acid showed better performance against E.coli and B.subtilis bacteria compared with AgNPs-PVP.In summary,this study highlights the potential of tartaric acid in AgNP synthesis and suggests an avenue for the development of stable AgNPs with versatile applications.
文摘The adsorption of Pb(II)on silica gel synthesized from chemical glass bottle waste has been studied.The effect of independent variables(adsorbent dose,initial concentration of Pb(II),contact time,and pH)on the Pb(II)removal from water was evaluated and optimized using the Response Surface Methodology(RSM).Under optimized conditions(adsorbent dose:20 mg;contact time:30 min;initial Pb(II)concentration:120 mg.L^(−1);and pH:8),the removal of Pb(II)was 99.77%.The adsorption equilibrium data obtained from the batch experiment were investigated using different isotherm models.The Langmuir isotherm model fits the experimental data.This shows that the surface of the silica gel synthesized from chemical bottles waste was covered by a Pb(II)monolayer.XRF analysis showed that the synthesized silica gel had a SiO_(2) content of 75.63%.Amorphous silica was observed from XRD analysis.SEM-EDX characterization showed that Pb was adsorbed on the silica gel surface.SEM analysis showed that silica gel has irregular particles with a surface area of 297.08 m2.g^(−1) with a pore radius of 15.74 nm calculated from BET analysis.
基金funded by Directorate of Research and Community Service(DRPM,Direktorat Riset dan Pengabdian Kepada Masyarakat)ITS through the ITS Research Local Grant(No.1727/PKS/ITS/2023).
文摘This research focuses on the effective removal of methylene blue dye using silica gel synthesized from chemical glass bottle waste as an environmentally friendly and cost-effective adsorbent.The adsorption process was optimized using Box-Behnken Design(BBD)and Response Surface Methodology(RSM)to investigate the influence of pH(6;8 and 10),contact time(15;30 and 45 min),adsorbent mass(30;50 and 70 mg),and initial concentration(20;50 and 80 mg/L)of the adsorbate on the adsorption efficiency.The BBD was conducted using Google Colaboratory software,which encompassed 27 experiments with randomly assigned combinations.The silica gel synthesized from chemical glass bottle was characterized by XRD,FTIR,SEM-EDX and TEM.The adsorption result was measured by spectrophotometer UV-Vis.The optimized conditions resulted in a remarkable methylene blue removal efficiency of 99.41%.Characterization of the silica gel demonstrated amorphous morphology and prominent absorption bands characteristic of silica.The Langmuir isotherm model best described the adsorption behavior,revealing chemisorption with a monolayer coverage of methylene blue on the adsorbent surface,and a maximum adsorption capacity of 82.02 mg/g.Additionally,the pseudo-second-order kinetics model indicated a chemisorption mechanism during the adsorption process.The findings highlight the potential of silica gel from chemical glass bottle waste as a promising adsorbent for wastewater treatment,offering economic and environmental benefits.Further investigations can explore its scalability,regenerability,and reusability for industrial-scale applications.
基金financial support from the Institut Teknologi Sepuluh Nopember for this work,under the Project Scheme of the Publication Writing and IPR Incentive Program(PPHKI)2024.
文摘Dyes are pervasive contaminants in wastewater,posing significant health risks to both humans and animals.Among the various methods employed for effective dye removal,adsorption has emerged as a highly promising approach due to its notable advantages,including high efficiency,cost-effectiveness,low energy consumption,and operational simplicity compared to alternative treatments.This comprehensive review focuses on investigating adsorbents derived from biowastes and biomass,specifically carbon-based and non-conventional adsorbents,for the removal of malachite green,a widely used dye known for its toxic and carcinogenic properties.Carbon-based adsorbents encompass two main types:activated carbon and biochar,while non-conventional adsorbents refer to powder sorbents without carbonaceous treatments.Extensive studies have reported remarkable findings,with achieved maximum removal percentages exceeding 98%and capacities reaching 250 mg/g.These results highlight the exceptional efficacy of the reviewed adsorbents in eliminating malachite green from wastewater.By exploring the potential of bio-based adsorbents,this review sheds light on sustainable and environmentally friendly solutions for mitigating dye pollution.
文摘Smartphone ownership among adolescents is getting common in this decade especially in Malaysia;Adolescent are strongly devoted to their smartphone and this may lead to smartphone addiction.Studies have reported that smartphone addiction has become an emerging social and health problem especially among the youth in many countries however there is lack of study among adolescents in Malaysia.This study aimed to examine the prevalence and factors associated with smartphone addiction among adolescents in Malaysia.This was a cross-sectional study involving adolescents from 15 primary care clinics throughout the country.Respondents were assessed on their smartphone activities using the Malaysian short version of the Smartphone addiction scale(SAS-M-SV).Multiple logistic regression was used to determine the predictors of smartphone addiction among adolescents.The study was conducted among 921 adolescents with 49.6%male(n=457).The mean age of adolescents was 16.4±2.4 years.The ethnicity distribution were 74.6%Malay,7.3%Chinese,4.7%Indian and 13.4%other ethnicities.The prevalence of smartphone addiction was 37.1%(342/921);37.4%in male and 36.9%in female.Based on multiple logistic regression analysis,longer duration of smartphone use per week was associated with higher odds of smartphone addiction among adolescent(odd ratio=1.005%,95%confidence interval=1.000–1.009,p-value=0.039).Smartphone addiction is present in nearly four in ten adolescents in Malaysia.Adolescents who spend longer duration in smartphone usage per week were associated with higher odds of having smartphone addiction.Parents should be more alert and vigilant about this finding.Hence,parents should limit their children from spending too much of time with smartphone in order to prevent their children from getting smartphone addiction.
基金Supported by the Project of Ministry of Science, Technology and Innovation, Malaysia (04-01-02-SF0559)
文摘The paper examines the propagation direction and velocity of large-scale traveling ionospheric disturbances （LST1Ds） during extreme geomagnetic storms in the 23rd solar cycle （e.g., October 2003 and November 2003 storms） using GPS observations. In the analysis, the time delay between the vertical total electron content （VTEC） structures at Scott Base, McMurdo, Davis and Casey GPS stations and the distance between these stations were the main parameters in the determination of LSTIDs propagation speed and direction. The observations during October and November 2003 storms show obvious time delay between the total electron content （TEC） enhancement signatures at these stations. The time delay suggests a movement of the ionospheric disturbances from higher to lower latitudes during the October storm with a velocity of 800-1 200 m/s and poleward propagation of LSTIDs during the November storm with a ve- locity of 300-400 m/s. The equatorward or poleward expansion of LSTIDs during the October and November 2003 storms is probably caused by the disturbances of the neutral temperature occurring close to the dayside convection throat or by the neutral wind oscillation induced by atmospheric gravity waves （AGW） launched from the aurora region.
文摘In the information-oriented society, there are increasing needs to conduct data communication with nearby devices/people. In this light, vibration-based communication method was proposed as one of possible communication means between adjacent devices. This method has been expected to provide an intuitive and safe communication by propagating vibration to a receiver device. This study proposes two types of techniques, which are multi-step ASK (Amplitude Shift Keying) with pseudo clock and PPM (Pulse Position Modulation), to achieve a stable vibration-based communication simply using smart device functions. These proposed techniques are then evaluated through some experiments using several types of smart devices. In addition, the effectiveness of the proposed methods is discussed based on the experimental results.
基金funded by Institute for Research and Community Services(LPPM,Lembaga Penelitian and Pengabdian Masyarakat)ITS(1438/PKS/ITS/2018)The research facilities were supported by Chemistry Department,Faculty Sciences,Institut Teknologi Sepuluh Nopember,Surabaya(ITS).
文摘Water-Soluble Chitosan(WSC)has been sucessfuly synthesized from squid pens waste.The synthesis of chitosan from chitin was carried out by optimization of deacetylation temperature and time.Chitin was obtained from squid pens waste by demineralization and deproteinization process.HCl 7%was used for demineralization and NaOH 10%at 60℃ was applied for deproteinization process.Deacetylation reaction was carried out at varied temperatures i.e.,60℃,70℃,80℃,90℃ and 100℃ in NaOH 50%solution for 10 hours.Deacetylation reaction time were varied for 2 hours,4 hours,6 hours,8 hours,and 10 hours.The crude chitosan obtained then reacted with H2O230%to depolymerize.The synthesis product obtained then characterized by FTIR.The result of squid chitin yield was 33.9%.The optimum temperature and time of chitosan deacetylation process were 90℃ for 8 hours as indicated by the value of deacetylation degree(DD)that equal to 83.94%at optimum temperature and 82.22%at optimum reaction time.The percentage of WSC yield at optimum temperature(90℃)and optimum time(8 hours)were 27.59%and 23.16%,respectively.WSC solubility test was done in water and HCl 0,1N.The solubility of 2.8325 mg/mL and 0.8125 mg/mL were obtained in acid medium and water medium,respectively.
文摘Biodiesel is a fossil fuel that is in demand to be developed because it is bio-renewable,biodegradable and environmentally friendly.Biodiesel produced from the transesterification reaction of vege Tab.oil using a base catalyst.CaO is the most developed catalyst for the reaction of transesterification of oil into biodiesel because it is cheap,the process is easy and has a high level of alkalinity.CaO is a cheap catalyst because it is easily obtained from natural ingredients.The use of CaO catalysts in the reaction formation of biodiesel continues to develop through modification with various porous materials and different oxide materials.In this paper,we discuss the development of CaO,the modification of CaO with a porous material and metal oxide,the mechanism of reaction of CaO and the kinetics of reactions that occur in the reaction transesterification of oil to biodiesel.
基金This work was supported by Fundamental Research Grant Scheme Universiti Sains Malaysia,203/PPSK/203.6712025.
文摘In this paper,we present a three-compartment of pharmacokinetics model with irreversible rate constants.The compartment consists of arterial blood,tissues and venous blood.Fick’s principle and the law of mass action were used to develop the model based on the diffusion process.The model is modified into a fractional pharmacokinetics model with the sense of Caputo derivative.The existence and uniqueness of the model are investigated and the positivity of the model is established.The behaviour of the model is investigated by implementing numerical algorithms for the numerical solution of the system of fractional differential equations.MATLAB software is used to plot the graphs for illustrating the variation of drug concentration concerning time.Therefore,the numerical simulations of the model are presented for different values ofαwhich verified the theoretical analysis.Besides,we also observed the pattern of the simulations at the three-compartment of the model by using different values of initial conditions.
文摘Capsule shells have been successfully fabricated from water-soluble chitosan(WSC)with the addition of alginate and Gembili starch.WSC was synthesized from crab shell chitosan by depolymerization reaction.The capsule shells were made with the composition of WSC:Alginate,2:1,3:1 and 4:1(w/w)with and without the addition of Gembili starch.Gembili starch was added with a ratio of Alginate:Starch,1:1(w/w).The capsule shell properties were evaluated according to Indonesian Pharmacopoeia standard.The solubility test showed that the capsule shells were comply with the standard.The highest degrees of swelling in water and HCl 0.1 N solution were 491.93%and 410.51%,respectively.The highest degradation percentages in water and HCl 0.1 N solution were 57.80%and 21.44%,respectively.The observation of physical appearance indicated that the capsule shell with WSC:Alginate:Starch in ratio of 3:1:1 has appearance close to commercial capsule shell.
基金funded by Fundamental Research Grant Scheme Universiti Sains Malaysia,Grant No.203/PJJAUH/6711688 received by S.A.M.Yatim.Url at http://www.research.usm.my/default.asp?tag=3&f=1&k=1.
文摘Many initial value problems are difficult to be solved using ordinary,explicit step-by-step methods because most of these problems are considered stiff.Certain implicit methods,however,are capable of solving stiff ordinary differential equations(ODEs)usually found in most applied problems.This study aims to develop a new numerical method,namely the high order variable step variable order block backward differentiation formula(VSVOHOBBDF)for the main purpose of approximating the solutions of third order ODEs.The computational work of the VSVO-HOBBDF method was carried out using the strategy of varying the step size and order in a single code.The order of the proposed method was then discussed in detail.The advancement of this strategy is intended to enhance the efficiency of the proposed method to approximate solutions effectively.In order to confirm the efficiency of the VSVO-HOBBDF method over the two ODE solvers in MATLAB,particularly ode15s and ode23s,a numerical experiment was conducted on a set of stiff problems.The numerical results prove that for this particular set of problem,the use of the proposed method is more efficient than the comparable methods.VSVO-HOBBDF method is thus recommended as a reliable alternative solver for the third order ODEs.
基金supported by Newton-Ungku Omar Grant (XX-2017-002)
文摘This study investigates the recent extreme temperature trends across 19 stations in the Klang Valley, Malaysia, over the period 2006^-16. Fourteen extreme index trends were analyzed using the Mann-Kendall non-parametric test, with Sen’s slope as a magnitude estimator. Generally, the annual daily mean temperature, daily mean maximum temperature, and daily mean minimum temperature in the Klang Valley increased significantly, by 0.07°C yr^-1, 0.07°C yr^-1 and 0.08°C yr^-1, respectively. For the warm temperature indices, the results indicated a significant upward trend for the annual maximum of maximum temperature, by 0.09°C yr^-1, and the annual maximum of minimum temperature, by 0.11°C yr^-1. The results for the total number of warm days and warm nights showed significant increasing trends of 5.02 d yr^-1 and 6.92 d yr^-1, respectively. For the cold temperature indices, there were upward trends for the annual minimum of maximum temperature, by 0.09°C yr^-1, and the annual minimum of minimum temperature, by 0.03°C yr^-1, concurrent with the decreases in the total number cold days (TX10P), with -3.80 d yr^-1, and cold nights (TN10P), with -4.33 d yr^-1. The 34°C and 37°C summer days results showed significant upward trends of 4.10 d yr^-1 and 0.25 d yr^-1, respectively. Overall, these findings showed upward warming trends in the Klang Valley, with the minimum temperature rate increasing more than that of the maximum temperature, especially in urban areas.
