Displaying publications 81 - 100 of 139 in total

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  1. Electrocoagulation using a rotated anode: A novel reactor design for textile wastewater treatment
    Naje AS, Chelliapan S, Zakaria Z, Abbas SA
    J Environ Manage, 2016 Jul 1;176:34-44.
    PMID: 27039362 DOI: 10.1016/j.jenvman.2016.03.034
    This paper investigates the optimum operational conditions of a novel rotated bed electrocoagulation (EC) reactor for the treatment of textile wastewater. The effect of various operational parameters such as rotational speed, current density (CD), operational time (RT), pH, temperature, and inter-electrode distance (IED) on the pollutant removal efficiency were examined. In addition, the consumption of aluminum (Al) and electrical energy, as well as operating costs at optimum conditions were also calculated. The results indicated that the optimum conditions for the treatment of textile wastewater were achieved at CD = 4 mA/cm(2), RT = 10 min, rotational speed = 150 rpm, pH = 4.57, temperature = 25 °C, and IED = 1 cm. The electrode consumption, energy consumption, and operating costs were 0.038 kg/m(3), 4.66 kWh/m(3) and 0.44 US$/m(3), respectively. The removal efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solid (TSS), turbidity and color were 97.10%, 95.55%, 98%, 96% and 98.50%, respectively, at the first 10 min of reaction time, while the phenol compound of the wastewater was almost entirely removed (99.99%). The experimental results confirm that the new reactor design with rotated anode impellers and cathode rings provided high treatment efficiency at a reduced reaction time and with lower energy consumption.
    Matched MeSH terms: Reaction Time
  2. Fabrication of interdigitated high-performance zinc oxide nanowire modified electrodes for glucose sensing
    Haarindraprasad R, Hashim U, Gopinath SC, Perumal V, Liu WW, Balakrishnan SR
    Anal Chim Acta, 2016 Jun 21;925:70-81.
    PMID: 27188319 DOI: 10.1016/j.aca.2016.04.030
    Diabetes is a metabolic disease with a prolonged elevated level of glucose in the blood leads to long-term complications and increases the chances for cardiovascular diseases. The present study describes the fabrication of a ZnO nanowire (NW)-modified interdigitated electrode (IDE) to monitor the level of blood glucose. A silver IDE was generated by wet etching-assisted conventional lithography, with a gap between adjacent electrodes of 98.80 μm. The ZnO-based thin films and NWs were amended by sol-gel and hydrothermal routes. High-quality crystalline and c-axis orientated ZnO thin films were observed by XRD analyses. The ZnO thin film was annealed for 1, 3 and 5 h, yielding a good-quality crystallite with sizes of 50, 100 and 110 nm, and the band gaps were measured as 3.26, 3.20 and 3.17 eV, respectively. Furthermore, a flower-modeled NW was obtained with the lowest diameter of 21 nm. Our designed ZnO NW-modified IDE was shown to have a detection limit as low as 0.03 mg/dL (correlation coefficient = 0.98952) of glucose with a low response time of 3 s, perform better than commercial glucose meter, suitable to instantly monitor the glucose level of diabetes patients. This study demonstrated the high performance of NW-mediated IDEs for glucose sensing as alternative to current glucose sensors.
    Matched MeSH terms: Reaction Time
  3. Fulltext Effect of Short-Term Mobile Phone Base Station Exposure on Cognitive Performance, Body Temperature, Heart Rate and Blood Pressure of Malaysians
    Malek F, Rani KA, Rahim HA, Omar MH
    Sci Rep, 2015;5:13206.
    PMID: 26286015 DOI: 10.1038/srep13206
    Individuals who report their sensitivity to electromagnetic fields often undergo cognitive impairments that they believe are due to the exposure of mobile phone technology. The aim of this study is to clarify whether short-term exposure at 1 V/m to the typical Global System for Mobile Communication and Universal Mobile Telecommunications System (UMTS) affects cognitive performance and physiological parameters (body temperature, blood pressure and heart rate). This study applies counterbalanced randomizing single blind tests to determine if sensitive individuals experience more negative health effects when they are exposed to base station signals compared with sham (control) individuals. The sample size is 200 subjects with 50.0% Idiopathic Environmental Intolerance attributed to electromagnetic fields (IEI-EMF) also known as sensitive and 50.0% (non-IEI-EMF). The computer-administered Cambridge Neuropsychological Test Automated Battery (CANTAB eclipse(TM)) is used to examine cognitive performance. Four tests are chosen to evaluate Cognitive performance in CANTAB: Reaction Time (RTI), Rapid Visual Processing (RVP), Paired Associates Learning (PAL) and Spatial Span (SSP). Paired sample t-test on the other hand, is used to examine the physiological parameters. Generally, in both groups, there is no statistical significant difference between the exposure and sham exposure towards cognitive performance and physiological effects (P's > 0.05).
    Matched MeSH terms: Reaction Time
  4. Chloroquine polymeric membrane electrodes: Development and applications
    Saad B, Kanapathy K, Ahmad MN, Hussin AH, Ismail Z
    Talanta, 1991 Dec;38(12):1399-402.
    PMID: 18965315
    Three main types of PVC solvent polymeric membrane ion-selective electrodes for chloroquine are described. They are based on three ion-pairing agents namely dipicrylamine (DPA), tetraphenylborate (TPB) or tetrakis(4-chlorophenyl)borate (TCPB) with either dioctylphenyl phosphonate (DOPP) or trioctyl phosphate (TOP) solvent mediator. All electrodes exhibit Nernstian responses, fast dynamic response times and a wide useful pH range. The best all-round electrode is based on TPB and TOP plasticizing solvent mediators with a limit of detection of 7.1 x 10(-6)M and was utilized for the assay of chloroquine in tablets. Direct potentiometric determinations with either the analyte addition method or the normal calibration method gave results comparable to the official method.
    Matched MeSH terms: Reaction Time
  5. Biosynthesis of butyl esters from crude oil of palm fruit and kernel using halophilic lipase secretion by Marinobacter litoralis SW-45
    Musa H, Kasim FH, Gunny AAN, Gopinath SCB, Ahmad MA
    3 Biotech, 2019 Aug;9(8):314.
    PMID: 31406636 DOI: 10.1007/s13205-019-1845-y
    Initially, a new moderate halophilic strain was locally isolated from seawater. The partial 16S rRNA sequence analysis positioned the organism in Marinobacter genus and was named 'Marinobacter litoralis SW-45'. This study further demonstrates successful utilization of the halophilic M. litoralis SW-45 lipase (MLL) for butyl ester synthesis from crude palm fruit oil (CPO) and kernel oil (CPKO) in heptane and solvent-free system, respectively, using hydroesterification. Hydrolysis and esterification of enzymatic [Thermomyces lanuginosus lipase (TLL)] hydrolysis of CPO and CPKO to free fatty acids (FFA) followed by MLL-catalytic esterification of the concentrated FFAs with butanol (acyl acceptor) to synthesize butyl esters were performed. A one-factor-at-a-time technique (OFAT) was used to study the influence of physicochemical factors on the esterification reaction. Under optimal esterification conditions of 40 and 45 °C, 150 and 230 rpm, 50% (v/v) biocatalyst concentration, 1:1 and 5:1 butanol:FFA, 9% and 15% (w/v) NaCl, 60 and 15 min reaction time for CPO- and CPKO-derived FFA esterification system, maximum ester conversion of 62.2% and 69.1%, respectively, was attained. Gas chromatography (GC) analysis confirmed the products formed as butyl esters. These results showed halophilic lipase has promising potential to be used for biosynthesis of butyl esters in oleochemical industry.
    Matched MeSH terms: Reaction Time
  6. Epoxidation and hydroxylation of liquid natural rubber
    Nur Hanis Adila Azhar, Nur Hanis Adila Azhar Hamizah Md Rasid, Siti Fairus M. Yusoff
    Sains Malaysiana, 2017;46:485-491.
    Liquid natural rubber (LNR) was functionalized into liquid epoxidized natural rubber (LENR) and hydroxylated LNR (LNROH)
    via oxidation using a Na2
    WO4
    /CH3
    COOH/H2
    O2
    catalytic system. Microstructures of LNR and functionalized LNRs
    were characterized using Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies. The
    effect of CH3
    COOH, H2
    O2
    , Na2
    WO4
    , reaction time and temperature. reaction time and temperature on epoxy content were
    investigated. LNR-OH was obtained when oxidation reaction was conducted at a longer reaction time, higher temperature
    or excess amount of catalyst. Thermogravimetric analysis (TGA) reported the thermal behavior of functionalized LNRs.
    Molecular weight and polydispersity index (PDI) were determined using gel permeation chromatography (GPC).
    Matched MeSH terms: Reaction Time
  7. Synthesisation of design features for multifunctional stretcher concepts
    Lim SH, Ng PK
    J Med Eng Technol, 2021 Feb;45(2):145-157.
    PMID: 33539247 DOI: 10.1080/03091902.2021.1873442
    A stretcher is a lightweight and portable apparatus used to facilitate the movement of patients who require medical care. While its design and functions have been known to man for over 600 years, there is still much room for improvement with regard to comfortability, mobility and ergonomics aspects. This study aims to synthesise design features from patents, journals and products for the conceptualisation of multifunctional stretchers. Based on the conceptual synthesis of this study, if a stretcher is redesigned to be foldable, then less storage space would be required, thus allowing the paramedic or medical person to store more stretchers and attend to multiple patients at a time. In comparison to a regular stretcher, a foldable stretcher would not only be smaller and more portable but would also help medical personnel reach the patient in a timelier manner. A reduction in response time for emergency medical services might increase the survival rate among patients who are in critical conditions. In the aspect of multifunctionality, the medical person may also be able to respond to different types of medical transportation needs. Multifunctional stretchers can increase the versatility of emergency medical service teams in adapting to different situations at a reduced cost.
    Matched MeSH terms: Reaction Time
  8. Fulltext Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers
    Ahmad W, Jabbar B, Ahmad I, Mohamed Jan B, Stylianakis MM, Kenanakis G, et al.
    Materials (Basel), 2021 Feb 22;14(4).
    PMID: 33671689 DOI: 10.3390/ma14041037
    Polymer composites are favorite materials for sensing applications due to their low cost and easy fabrication. In the current study, composite nanofibers consisting of polyethylene oxide (PEO), oxidized multi-walled carbon nanotubes (MWCNT) and copper oxide (CuO) nanoparticles with 1% and 3% of fillers (i.e., PEO-CuO-MWCNT: 1%, and PEO-CuO-MWCNT: 3%) were successfully developed through electrospinning for humidity sensing applications. The composite nanofibers were characterized by FTIR, XRD, SEM and EDX analysis. Firstly, they were loaded on an interdigitated electrode (IDE), and then the humidity sensing efficiency was investigated through a digital LCR meter (E4980) at different frequencies (100 Hz-1 MHz), as well as the percentage of relative humidity (RH). The results indicated that the composite nanofibers containing 1% and 3% MWCNT, combined with CuO in PEO polymer matrix, showed potent resistive and capacitive response along with high sensitivity to humidity at room temperature in an RH range of 30-90%. More specifically, the PEO-CuO-MWCNT: 1% nanocomposite displayed a resistive rapid response time within 3 s and a long recovery time of 22 s, while the PEO-CuO-MWCNT: 3% one exhibited 20 s and 11 s between the same RH range, respectively.
    Matched MeSH terms: Reaction Time
  9. Fulltext Synthesis and characterization of rice husk biochar via hydrothermal carbonization for wastewater treatment and biofuel production
    Hossain N, Nizamuddin S, Griffin G, Selvakannan P, Mubarak NM, Mahlia TMI
    Sci Rep, 2020 Nov 02;10(1):18851.
    PMID: 33139793 DOI: 10.1038/s41598-020-75936-3
    The recent implication of circular economy in Australia spurred the demand for waste material utilization for value-added product generations on a commercial scale. Therefore, this experimental study emphasized on agricultural waste biomass, rice husk (RH) as potential feedstock to produce valuable products. Rice husk biochar (RB) was obtained at temperature: 180 °C, pressure: 70 bar, reaction time: 20 min with water via hydrothermal carbonization (HTC), and the obtained biochar yield was 57.9%. Enhancement of zeta potential value from - 30.1 to - 10.6 mV in RB presented the higher suspension stability, and improvement of surface area and porosity in RB demonstrated the wastewater adsorption capacity. Along with that, an increase of crystallinity in RB, 60.5%, also indicates the enhancement of the catalytic performance of the material significantly more favorable to improve the adsorption efficiency of transitional compounds. In contrast, an increase of the atomic O/C ratio in RB, 0.51 delineated high breakdown of the cellulosic component, which is favorable for biofuel purpose. 13.98% SiO2 reduction in RB confirmed ash content minimization and better quality of fuel properties. Therefore, the rice husk biochar through HTC can be considered a suitable material for further application to treat wastewater and generate bioenergy.
    Matched MeSH terms: Reaction Time
  10. Fulltext A New and All-Solid-State Potentiometric Aluminium Ion Sensor for Water Analysis
    Ying KS, Heng LY, Hassan NI, Hasbullah SA
    Sensors (Basel), 2020 Dec 03;20(23).
    PMID: 33287113 DOI: 10.3390/s20236898
    An all-solid-state potentiometric electrode system for aluminium ion determination was developed with a new aluminium ion sensor as the working electrode based on a new ionophore for aluminium ion, 1,1'-[(methylazanediyl)bis(ethane-2,1-diyl)]bis[3-(naphthalen-1-yl)thiourea] (ACH). The reference electrode was a potassium ion sensor, which acts as a pseudo-reference. Both electrodes were made from Ag/AgCl screen-print electrodes fabricated from a non-plasticized and photocurable poly(n-butyl acrylate) membrane that contained various other membrane components. The pseudo-reference potential based on the potassium ion sensor was fixed in 0.050 M KNO3, and such concentration of K+ ion did not interfere with the measurement of the Al3+ ion using the aluminium sensor. With such a pseudo-reference and in the presence of 0.050 M KNO3 as a background medium, the aluminium sensor measured changes of aluminium ion concentrations linearly from 10-6 to 10-2 M Al3+ ion with a Nernstian response of 17.70 ± 0.13 mV/decade. A low detection limit of 2.45 × 10-7 M was achieved with this all-solid-state potentiometric system. The aluminium sensor was insensitive to pH effects from 2.0 to 8.0 with a response time of less than 50 s. Under optimum conditions, a lifetime of 49 days was achieved with good sensor selectivity, reversibility, repeatability, and reproducibility. The all-solid-state electrode system was applied to analyze the Al3+ ion content of water samples from a water treatment plant. Compared with the conventional potentiometric detection system for aluminium ions, the new all-solid-state aluminium ion sensor incorporating a pseudo-reference from the potassium sensor demonstrated similar analytical performance. It thus provided a convenient means of aluminium content analysis in water treatment plants.
    Matched MeSH terms: Reaction Time
  11. Fulltext Microwave Hydrothermal Carbonization of Rice Straw: Optimization of Process Parameters and Upgrading of Chemical, Fuel, Structural and Thermal Properties
    Nizamuddin S, Qureshi SS, Baloch HA, Siddiqui MTH, Takkalkar P, Mubarak NM, et al.
    Materials (Basel), 2019 Jan 28;12(3).
    PMID: 30696042 DOI: 10.3390/ma12030403
    The process parameters of microwave-induced hydrothermal carbonization (MIHTC) play an important role on the hydrothermal chars (hydrochar) yield. The effect of reaction temperature, reaction time, particle size and biomass to water ratio was optimized for hydrochar yield by modeling using the central composite design (CCD). Further, the rice straw and hydrochar at optimum conditions have been characterized for energy, chemical, structural and thermal properties. The optimum condition for hydrochar synthesis was found to be at a 180 °C reaction temperature, a 20 min reaction time, a 1:15 weight per volume (w/v) biomass to water ratio and a 3 mm particle size, yielding 57.9% of hydrochar. The higher heating value (HHV), carbon content and fixed carbon values increased from 12.3 MJ/kg, 37.19% and 14.37% for rice straw to 17.6 MJ/kg, 48.8% and 35.4% for hydrochar. The porosity, crystallinity and thermal stability of the hydrochar were improved remarkably compared to rice straw after MIHTC. Two characteristic peaks from XRD were observed at 2θ of 15° and 26°, whereas DTG peaks were observed at 50⁻150 °C and 300⁻350 °C for both the materials. Based on the results, it can be suggested that the hydrochar could be potentially used for adsorption, carbon sequestration, energy and agriculture applications.
    Matched MeSH terms: Reaction Time
  12. Application of response surface methodology for the optimization of polycyclic aromatic hydrocarbons degradation from potable water using photo-Fenton oxidation process
    Abd Manan TSB, Khan T, Sivapalan S, Jusoh H, Sapari N, Sarwono A, et al.
    Sci Total Environ, 2019 May 15;665:196-212.
    PMID: 30772550 DOI: 10.1016/j.scitotenv.2019.02.060
    Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds, composed of benzene rings. The objective of this research was to identify the optimum condition for the degradation of PAHs contaminated water using photo-Fenton oxidation process via response surface methodology (RSM). Aqueous solution was prepared and potable water samples were collected from water treatment plants in Perak Tengah, Perak, Malaysia in September 2016. The reaction time, pH, molarity of H2O2 and FeSO4 were analyzed followed by RSM using aqueous solution. A five level central composite design with quadratic model was used to evaluate the effects and interactions of these parameters. The response variable was the percentage of total organic carbon (TOC) removal. PAHs quantification was done using gas chromatography mass spectrometry analysis. The regression line fitted well with the data with R2 value of 0.9757. The lack of fit test gives the highest value of Sum of Squares (15,666.64) with probability F value 0.0001 showing significant quadratic model. The optimum conditions were established corresponding to the percentage of TOC removal. The PAHs removal efficiency for potable water samples ranged from 76.4% to 91% following the first order of kinetic rates with R2 values of >0.95. Conventional water treatment techniques are not effective for PAHs removal. Thus, advanced oxidation processes may be considered as an alternative to conventional water treatment techniques in Malaysia and other developing countries.
    Matched MeSH terms: Reaction Time
  13. Fulltext Investigating the use of date seed for removal of boron from seawater
    Ahmed, Moussa Mohamed, Nik Rashida Nik Abdul Ghani, Jami, Mohammed Saedi, Mirghani, Mohamed Elwathig Saeed, Md. Noor Salleh
    Biological and Natural Resources Engineering Journal, 2020;3(2):55-73.
    MyJurnal
    Boron has been classified as a drinking water pollutant in many countries. It is harmful to many plants, exceptionally sensible plants, and human health. Therefore, boron level needs to be decreased to 0.3 mg/L for drinking water and within 0.5 mg/L to 1 mg/L for irrigation water. In this study, various operational parameters namely pH, contact time and liquid/solid ratio were investigated to determine the potential of using date seed (or date pit or date stone) to remove boron from seawater. This study's main objective was to determine boron adsorption capacities of date seeds prepared by various methods (i.e., powdered, activated, acid-treated and defatted seed) by batch adsorption process using boron contaminated synthetic seawater. The process parameters of the selected biosorbent among the four date seed preparations methods were optimized. The surface characteristics were analyzed by using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The results showed that acid-treated date seed was the best biosorbent in terms of removing 89.18% boron from aqueous solution at neutral pH, liquid to solid ratio of 5 within 2 hours of reaction time at room temperature (25°C±2°C).
    Matched MeSH terms: Reaction Time
  14. Insight into the Rhizomucor miehei lipase supported on chitosan-chitin nanowhiskers assisted esterification of eugenol to eugenyl benzoate
    Abd Manan FM, Attan N, Zakaria Z, Mahat NA, Abdul Wahab R
    J Biotechnol, 2018 May 28;280:19-30.
    PMID: 29852195 DOI: 10.1016/j.jbiotec.2018.05.015
    To overcome drawbacks in the conventional chemical route to synthesize eugenyl benzoate, immobilized Rhizomucor miehei lipase (RML) as the biocatalyst was proposed. The RML conjugated to a hybrid support consisting of biopolymers, chitosan (CS) and chitin nanowhiskers (CNWs). 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDAC) was used as the crosslinker to bind the lipase. Immobilization of RML was the highest on crosslinked CS/CNWs which gave a protein loading of ∼8.12 mg/g, corresponding to specific and residual activity of 537 U/g and 137%, respectively. Fourier transform infrared spectroscopy, thermogravimetric analysis-differential thermogravimetry, field emission scanning electron and atomic force microscopy of RML-CS/CNWs revealed that RML was successfully attached to the surface of crosslinked CS/CNWs. Under an optimized condition, the highest yield of eugenyl benzoate (56.3%) was attained after 5 h using 3 mg/mL of RML-CS/CNWs with molar ratio of eugenol: benzoic acid of 3:1, as compared to only 47.3% for the free RML. Analyses of FTIR and NMR on purified eugenyl benzoate affirmed that the ester was successfully produced in the enzymatic esterification. Therefore, the use of the RML-CS/CNWs biocatalysts appears promising to afford good yields of eugenyl benzoate within a relatively shorter reaction time.
    Matched MeSH terms: Reaction Time
  15. Fulltext Synthesis and characterization of Pd(II) and Ni(II) complexes of Schiff bases and catalytic activity of Pd(II) complexes
    Amalina Mohd Tajuddin, Hadariah Bahron, Shahrul Nizam Ahmad
    Scientific Research Journal, 2015;12(2):0-0.
    MyJurnal
    Six new Pd(II) and Ni(II) metal complexes of N, O-bidentate (L1, L2) and ONNO-tetradentate (L3) Schiff base ligands have been synthesized. The compounds were characterized via various physicochemical and spectroscopic techniques namely elemental analysis (CHN), FT-IR, 1H and 13C NMR as well as magnetic susceptibility measurement. All complexes showed diamagnetism indicating that they are square planar complexes. Catalytic performance of Pd(L1)2 and Pd(L2)2 were investigated for Heck cross-coupling reaction under optimum operating parameters, monitored using GC-FID for 6 h of reaction time in inert conditions. High catalytic activities of up to 90% were observed in the presence of triethylamine as base and DMA as solvent at 100oC with 1 mmol% catalyst loading. The mechanism of catalyzed Heck reaction is proposed to go through a series of conversion of Pd(0)/Pd(II).
    Matched MeSH terms: Reaction Time
  16. Fulltext Synthesis of jatropha curcas-based methyl ester and ethyl ester as biodiesel feedstocks
    Azhari Muhammad Syam, Robiah Yunus, Tinia Idaty Mohd. Ghazi, Choong, Thomas Shean Yaw
    Pertanika Journal of Science & Technology, 2012;20(1):165-173.
    MyJurnal
    Research on the use of Jatropha curcas triglycerides as biodiesel feedstock has received worldwide attention due to its inherent characteristics. Unlike palm oil, J. curcas oil is not edible, and thus, it will not disturb the food supply. However, to the researchers' experiences with the synthesis of J. curcas, oil-based biodiesel has shown that the fuel characteristics depend largely on the type of alcohol used as the excess reactants. Transesterification reaction is chosen for this process with sodium methoxide as the catalyst. Comparison studies on the yield of esters using methanol and ethanol, as well as the impacts on the reaction rate are discussed. The effects of reaction time and molar ratio on the reaction conversion are also examined. The determination of reaction yield is based on the conversion of triglycerides into alkyl esters as the main product. The findings are described as follows: the highest percentage yield of product is attained at 96% for methanol as an excess reactant, and this is 90% when ethanol is used. The optimum conditions of parameters are achieved at 6:1 molar ratio of alcohol to triglycerides, 50 min of reaction time and reaction temperature of 65°C for methanol and 75°C for ethanol. The biodiesel properties of both ester fuels were determined according to the existing standards for biodiesel and compared to the characteristics of diesel fuel.
    Matched MeSH terms: Reaction Time
  17. Synthesis of vegetable-oil based polymer by terpolymerization of epoxidized soybean oil, propylene oxide and carbon dioxide
    Shaarani FW, Bou JJ
    Sci Total Environ, 2017 Nov 15;598:931-936.
    PMID: 28458211 DOI: 10.1016/j.scitotenv.2017.04.184
    Although carbon dioxide (CO2) is well known as one of the major green-house gases, it is also an economical C1 resource. Thus, CO2has been regarded as an appealing starting material for the synthesis of polymers, like polycarbonates by the reaction with epoxides. Herein the reaction between natural epoxidized soybean oil (ESO), propylene oxide (PO) and CO2under high pressure (4.0MPa) with the presence of Co-Zn double metal cyanide (Co-Zn DMC) catalyst was studied. Temperature and reaction time were varied accordingly and the products obtained were characterized by FTIR, GPC and1H NMR. The results obtained indicate the formation of polycarbonates in the samples collected with yields vary from 60 to 85%. The number average molecular weight (Mn) of the resultant polymer prepared at reaction temperature of 80°C and reaction time of 6h can reach up to 6498g/mol.
    Matched MeSH terms: Reaction Time
  18. Impact of virtual reality games on psychological well-being and upper limb performance in adults with physical disabilities: A pilot study
    Singh DKA, Rahman NNA, Seffiyah R, Chang SY, Zainura AK, Aida SR, et al.
    Med J Malaysia, 2017 04;72(2):119-121.
    PMID: 28473675 MyJurnal
    INTRODUCTION: There is limited information regarding the effects of interactive virtual reality (VR) games on psychological and physical well-being among adults with physical disabilities. We aimed to examine the impact of VR games on psychological well-being, upper limb motor function and reaction time in adults with physical disabilities.

    METHODS: Fifteen participants completed the intervention using Wii VR games in this pilot study. Depressive, Anxiety and Stress Scales (DASS) and Capabilities of Upper Extremity (CUE) questionnaires were used to measure psychological well-being and upper limb motor function respectively. Upper limb reaction time was measured using reaction time test.

    RESULTS: Results showed that there was a significant difference (p<0.05) in DASS questionnaire and average reaction time score after intervention.

    CONCLUSION: There is a potential for using interactive VR games as an exercise tool to improve psychological wellbeing and upper limb reaction time among adults with disabilities.

    Matched MeSH terms: Reaction Time
  19. Fulltext Performance of combined persulfate/aluminum sulfate for landfill leachate treatment
    Abu Amr SS, Alkarkhi AFM, Alslaibi TM, Abujazar MSS
    Data Brief, 2018 Aug;19:951-958.
    PMID: 29900392 DOI: 10.1016/j.dib.2018.05.111
    Although landfilling is still the most suitable method for solid waste disposal, generation of large quantity of leachate is still considered as one of the main environmental problem. Efficient treatment of leachate is required prior to final discharge. Persulfate (S2O82-) recently used for leachate oxidation, the oxidation potential of persulfate can be improved by activate and initiate sulfate radical. The current data aimed to evaluate the performance of utilizing Al2SO4 reagent for activation of persulfate to treat landfill leachate. The data on chemical oxygen demand (COD), color, and NH3-H removals at different setting of the persulfate, Al2SO4 dosages, pH, and reaction time were collected using a central composite design (CCD) were measured to identify the optimum operating conditions. A total of 30 experiments were performed, the optimum conditions for S2O82-/Al2SO4 oxidation process was obtained. Quadratic models for chemical oxygen demand (COD), color, and NH3-H removals were significant with p-value 
    Matched MeSH terms: Reaction Time
  20. Biodiesel Production from Citrillus colocynthis Oil Using Enzymatic Based Catalytic Reaction and Characterization Studies
    Nehdi IA, Sbihi HM, Blidi LE, Rashid U, Tan CP, Al-Resayes SI
    Protein Pept Lett, 2018;25(2):164-170.
    PMID: 28240158 DOI: 10.2174/0929866524666170223150839
    BACKGROUND: Biodiesel is a green fuel consisting of long chain fatty acid monoalkyl esters, which can be blended with diesel or used alone which is usually produced from vegetable oils/fats by either lipasecatalyzed transesterification. In this investigation, an enzyme (Novozym 435) catalyzed process was optimized to prepare methyl esters from crude Citrullus colocynthis oil (CCO) by transesterification of CCO with methanol. However, as per our knowledge, lipase-catalyzed transesterification have not been used for biodiesel production from Citrullus colocynthis.

    OBJECTIVE: The purpose of this work was to transesterify the CCO in the presence of Candida antarctica lipase as catalyst and methanol. Additionally, the physicochemical parameters/fuel properties of the Citrullus colocynthis methyl ester (CCME) were assessed and compared.

    METHODS: Lipase-catalyzed reactions were carried out in three necked flask (50 mL) attached with reflux condenser and thermometer, immersed in oil bath at constant stirring speed (400 rpm). The reaction mixture was consisted of CCO and varying the calculated amount of methanol, tert-butyl alcohol, and Novozym 435. The experimental parameters reaction time, methanol/oil molar ratio, reaction temperature, tert-butanol content, Novozym 435 content and water content were optimized for the transesterification reaction. The CCME yield was measured using gas chromatograph. The fuel properties of the produced CCME were determined as per American Society for Testing and Materials (ASTM) and European (EN) biodiesel standard methods.

    RESULTS: In this study, an enzymatic catalyst was employed to synthesize the CCME from CCO via transesterification. Several variables affecting the CCME yield were optimized as lipase quantity (4%), water content (0.5%), methanol/oil molar ratio (5:1), reaction temperature (43 °C), reaction medium composition (80% tertbutanol/ oil), and reaction time (3.7 h). A CCME yield of 97.8% was achieved using enzyme catalyzed transesterification of CCO under optimal conditions. The significant biodiesel fuel properties of CCME, i.e. cloud point (0.70 °C); cetane number (49.07); kinematic viscosity (2.27 mm2/s); flash point (143 °C); sulfur content (2 ppm) density (880 kg/m3) and acid value (0.076 mg KOH/g) were appraised. CCME also exhibited long-term storage stability (4.80 h) and all the biodiesel fuel properties were within the range of standards (ASTM D6751 and EN 14214).

    CONCLUSION: The lipase-catalyzed transesterification produced better conversion than the base-catalyzed reaction. The fuel properties of CCME were within the limits of the ASTM D6751 and EN14214 standards. Furthermore, CCME showed good oxidative stability and a long shelf life due its high natural antioxidant content. CCME showed better fuel properties and long-term storage stability due to which it can be used as a potential alternative fuel.

    Matched MeSH terms: Reaction Time
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