Displaying publications 61 - 80 of 306 in total

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  1. High yield production of sugars from deproteinated palm kernel cake under microwave irradiation via dilute sulfuric acid hydrolysis
    Fan SP, Jiang LQ, Chia CH, Fang Z, Zakaria S, Chee KL
    Bioresour Technol, 2014 Feb;153:69-78.
    PMID: 24342947 DOI: 10.1016/j.biortech.2013.11.055
    Recent years, great interest has been devoted to the conversion of biomass-derived carbohydrate into sugars, such as glucose, mannose and fructose. These are important versatile intermediate products that are easily processed into high value-added biofuels. In this work, microwave-assisted dilute sulfuric acid hydrolysis of deproteinated palm kernel cake (DPKC) was systematically studied using Response Surface Methodology. The highest mannose yield (92.11%) was achieved at the optimized condition of 148°C, 0.75N H2SO4, 10min 31s and substrate to solvent (SS) ratio (w/v) of 1:49.69. Besides that, total fermentable sugars yield (77.11%), was obtained at 170°C, 0.181N H2SO4, 6min 6s and SS ratio (w/v) of 1:40. Ridge analysis was employed to further verify the optimum conditions. Thus, this work provides fundamental data of the practical use of DPKC as low cost, high yield and environmental-friendly material for the production of mannose and other sugars.
    Matched MeSH terms: Microwaves*
  2. A combined microwave pretreatment/solvent extraction process for the production of oil from palm fruit: optimisation, oil quality and effect of prolonged exposure
    Tan JC, Chuah CH, Cheng SF
    J Sci Food Agric, 2017 Apr;97(6):1784-1789.
    PMID: 27470073 DOI: 10.1002/jsfa.7975
    BACKGROUND: Conventional palm oil milling involves multiple stages after fruit collection; in particular, oil clarification introduces water into the pressed oil, which results in a large quantity of wastewater.

    RESULTS: A combined process of microwave pretreatment and solvent extraction to mill crude palm oil, without introducing water or steam, is described. An excellent yield (up to 30%) of oil was obtained with pretreatment in a 42 L, 1000 W and 2450 MHz microwave oven followed by hexane extraction. The optimum conditions (10 min microwave pretreatment and 12 h solvent extraction) yielded an oil with a low free fatty acid content (<1.0%) and an acceptable anisidine value (<3.0 meq kg(-1) ). The oil had a fatty acid composition not resembling those of conventional crude palm oil and crude palm kernel oil. In the pretreatment, the leached oil had 6.3% lauric acid whereas the solvent extracted oil had only 1.5% lauric acid. Among the factors affecting the oil quality, microwave pretreatment affected the oil quality significantly; however, an optimised duration that would ensure high efficiency in solvent extraction also resulted in ruptured fruitlets, although not to the extent of causing excessive oxidation. In fact, microwave pretreatment should exceed 12 min; after only 15 min, the oil had 1-methylcyclopentanol (12.96%), 1-tetradecanol (9.44%), 1-nonadecene (7.22%), nonanal (7.13%) and 1-tridecene (5.09%), which probably arose from the degradation of fibres.

    CONCLUSION: Microwave pretreatment represents an alternative milling process for crude palm oil compared with conventional processes in the omission of wet treatment with steam. © 2016 Society of Chemical Industry.

    Matched MeSH terms: Microwaves
  3. Fulltext An Improved Fabrication Technique for the 3-D Frequency Selective Surface based on Water Transfer Printing Technology
    Harnois M, Himdi M, Yong WY, Rahim SKA, Tekkouk K, Cheval N
    Sci Rep, 2020 Feb 03;10(1):1714.
    PMID: 32015444 DOI: 10.1038/s41598-020-58657-5
    Manufacturing an array of high-quality metallic pattern layers on a dielectric substrate remains a major challenge in the development of flexible and 3-D frequency selective surfaces (FSS). This paper proposes an improved fabrication solution for the 3-D FSS based on water transfer printing (WTP) technology. The main advantages of the proposed solution are its ability to transform complicated 2-D planar FSS patterns into 3-D structures while improving both manufacturing quality and production costs. WTP technology makes use of water surface tension to keep the thin metallic patterns of the proposed FSS floating flat with the absence of a solid planar substrate. This feature enables these metallic FSS patterns to be transferred onto 3-D structures through a dipping process. To test the effectiveness of the proposed technique, the FSS was designed using computer simulation software Microwave Studio to obtain the numerical performance of the FSS structure. The WTP technology was then used to fabricate the proposed FSS prototype before its performance was tested experimentally. The measurement results agreed well with the numerical results, indicating the proposed manufacturing solution would support the development of complicated 3-D electronics devices, such as conformal antenna arrays and metamaterials.
    Matched MeSH terms: Microwaves
  4. Fulltext Microwave-Assisted Synthesis of Highly-Crumpled, Few-Layered Graphene and Nitrogen-Doped Graphene for Use as High-Performance Electrodes in Capacitive Deionization
    Amiri A, Ahmadi G, Shanbedi M, Savari M, Kazi SN, Chew BT
    Sci Rep, 2015;5:17503.
    PMID: 26643279 DOI: 10.1038/srep17503
    Capacitive deionization (CDI) is a promising procedure for removing various charged ionic species from brackish water. The performance of graphene-based material in capacitive deionization is lower than the expectation of the industry, so highly-crumpled, few-layered graphene (HCG) and highly-crumpled nitrogen-doped graphene (HCNDG) with high surface area have been introduced as promising candidates for CDI electrodes. Thus, HCG and HCNDG were prepared by exfoliation of graphite in the presence of liquid-phase, microwave-assisted methods. An industrially-scalable, cost-effective, and simple approach was employed to synthesize HCG and HCNDG, resulting in few-layered graphene and nitrogen-doped graphene with large specific surface area. Then, HCG and HCNDG were utilized for manufacturing a new class of carbon nanostructure-based electrodes for use in large-scale CDI equipment. The electrosorption results indicated that both the HCG and HCNDG have fairly large specific surface areas, indicating their huge potential for capacitive deionization applications.
    Matched MeSH terms: Microwaves
  5. Cold-pressed rapeseed (Brassica napus) oil: Chemistry and functionality
    Chew SC
    Food Res Int, 2020 05;131:108997.
    PMID: 32247493 DOI: 10.1016/j.foodres.2020.108997
    Rapeseed oil is the second most abundant produced edible oil in the world with low erucic acid and low glucosinolate. Thus, the quality of rapeseed oil had attracted global attention. Cold-pressed rapeseed oil appeared to be a preferred choice than refined oil as no solvent and less processing involved in the cold-pressing. The methods of cold-pressing and microwave pre-treatment on the extraction yield and bioactive compounds of rapeseed oil have been reviewed in this paper. Cold-pressed rapeseed oil offers health benefits due to its preserved fatty acid profile and bioactive compounds. High phenolic compounds, tocopherols, phytosterols, and carotenoids contents in the cold-pressed rapeseed oil offer health benefits like regulating blood lipid profile, insulin sensitivity, and glycemic control, as well as offer antioxidant and cytotoxic activity. Besides using as edible oil, cold-pressed rapeseed oil find applications in animal feed, chemical, and fuel.
    Matched MeSH terms: Microwaves
  6. Fulltext Microwave Imaging Sensor Using Low Profile Modified Stacked Type Planar Inverted F Antenna
    Islam MT, Ullah MA, Alam T, Singh MJ, Cho M
    Sensors (Basel), 2018 Sep 05;18(9).
    PMID: 30189632 DOI: 10.3390/s18092949
    Microwave imaging is the technique to identify hidden objects from structures using electromagnetic waves that can be applied in medical diagnosis. The change of dielectric property can be detected using microwave antenna sensor, which can lead to localization of abnormality in the human body. This paper presents a stacked type modified Planar Inverted F Antenna (PIFA) as microwave imaging sensor. Design and performance analysis of the sensor antenna along with computational and experimental analysis to identify concealed object has been investigated in this study. The dimension of the modified PIFA radiating patch is 40 × 20 × 10 mm³. The reflector walls used, are 45 mm in length and 0.2-mm-thick inexpensive copper sheet is considered for the simulation and fabrication which addresses the problems of high expenses in conventional patch antenna. The proposed antenna sensor operates at 1.55⁻1.68 GHz where the maximum realized gain is 4.5 dB with consistent unidirectional radiation characteristics. The proposed sensor antenna is used to identify tumor in a computational human tissue phantom based on reflection and transmission coefficient. Finally, an experiment has been performed to verify the antenna's potentiality of detecting abnormality in realistic breast phantom.
    Matched MeSH terms: Microwaves
  7. Fulltext Ultra-Wideband (UWB) Antenna Sensor Based Microwave Breast Imaging: A Review
    Mahmud MZ, Islam MT, Misran N, Almutairi AF, Cho M
    Sensors (Basel), 2018 Sep 05;18(9).
    PMID: 30189633 DOI: 10.3390/s18092951
    Globally, breast cancer is reported as a primary cause of death in women. More than 1.8 million new breast cancer cases are diagnosed every year. Because of the current limitations on clinical imaging, researchers are motivated to investigate complementary tools and alternatives to available techniques for detecting breast cancer in earlier stages. This article presents a review of concepts and electromagnetic techniques for microwave breast imaging. More specifically, this work reviews ultra-wideband (UWB) antenna sensors and their current applications in medical imaging, leading to breast imaging. We review the use of UWB sensor based microwave energy in various imaging applications for breast tumor related diseases, tumor detection, and breast tumor detection. In microwave imaging, the back-scattered signals radiating by sensors from a human body are analyzed for changes in the electrical properties of tissues. Tumorous cells exhibit higher dielectric constants because of their high water content. The goal of this article is to provide microwave researchers with in-depth information on electromagnetic techniques for microwave imaging sensors and describe recent developments in these techniques.
    Matched MeSH terms: Microwaves
  8. Fulltext Antioxidant Activity, and Volatile and Phytosterol Contents of Strobilanthes crispus Dehydrated Using Conventional and Vacuum Microwave Drying Methods
    Chua LYW, Chua BL, Figiel A, Chong CH, Wojdyło A, Szumny A, et al.
    Molecules, 2019 04 09;24(7).
    PMID: 30970652 DOI: 10.3390/molecules24071397
    The preservation of active constituents in fresh herbs is affected by drying methods. An effective drying method for Strobilanthes crispus which is increasingly marketed as an important herbal tea remains to be reported. This study evaluated the effects of conventional and new drying technologies, namely vacuum microwave drying methods, on the antioxidant activity and yield of essential oil volatiles and phytosterols. These drying methods included convective drying (CD) at 40 °C, 50 °C, and 60 °C; vacuum microwave drying (VMD) at 6, 9, and 12 W/g; convective pre-drying and vacuum microwave finish drying (CPD-VMFD) at 50 °C and 9 W/g; and freeze-drying (FD). GC–MS revealed 33 volatiles, and 2-hexen-1-ol, 2-hexenal, 1-octen-3-ol, linalool, and benzaldehyde were major constituents. The compounds β-sitosterol and α-linolenic acid were the most abundant phytosterol and fatty acid, respectively, in fresh S. crispus. The highest phenolic content was achieved with CD at 60 °C. The highest antioxidant activity was obtained with CD at 40 °C and VMD at 9 W/g. On the contrary, the highest total volatiles and phytosterols were detected with CD at 50 °C and VMD at 9 W/g, respectively. This study showed that CD and VMD were effective in producing highly bioactive S. crispus. A suitable drying parameter level, irrespective of the drying method used, was an important influencing factor.
    Matched MeSH terms: Microwaves*
  9. Fulltext Microwave brain imaging system to detect brain tumor using metamaterial loaded stacked antenna array
    Hossain A, Islam MT, Beng GK, Kashem SBA, Soliman MS, Misran N, et al.
    Sci Rep, 2022 Oct 01;12(1):16478.
    PMID: 36183039 DOI: 10.1038/s41598-022-20944-8
    In this paper, proposes a microwave brain imaging system to detect brain tumors using a metamaterial (MTM) loaded three-dimensional (3D) stacked wideband antenna array. The antenna is comprised of metamaterial-loaded with three substrate layers, including two air gaps. One 1 × 4 MTM array element is used in the top layer and middle layer, and one 3 × 2 MTM array element is used in the bottom layer. The MTM array elements in layers are utilized to enhance the performance concerning antenna's efficiency, bandwidth, realized gain, radiation directionality in free space and near the head model. The antenna is fabricated on cost-effective Rogers RT5880 and RO4350B substrate, and the optimized dimension of the antenna is 50 × 40 × 8.66 mm3. The measured results show that the antenna has a fractional bandwidth of 79.20% (1.37-3.16 GHz), 93% radiation efficiency, 98% high fidelity factor, 6.67 dBi gain, and adequate field penetration in the head tissue with a maximum of 0.0018 W/kg specific absorption rate. In addition, a 3D realistic tissue-mimicking head phantom is fabricated and measured to verify the performance of the antenna. Later, a nine-antenna array-based microwave brain imaging (MBI) system is implemented and investigated by using phantom model. After that, the scattering parameters are collected, analyzed, and then processed by the Iteratively Corrected delay-multiply-and-sum algorithm to detect and reconstruct the brain tumor images. The imaging results demonstrated that the implemented MBI system can successfully detect the target benign and malignant tumors with their locations inside the brain.
    Matched MeSH terms: Microwaves*
  10. Green Synthesis, Antioxidant, and Plant Growth Regulatory Activities of Novel α-Furfuryl-2-alkylaminophosphonates
    Nadiveedhi MR, Nuthalapati P, Gundluru M, Yanamula MR, Kallimakula SV, Pasupuleti VR, et al.
    ACS Omega, 2021 Feb 02;6(4):2934-2948.
    PMID: 33553912 DOI: 10.1021/acsomega.0c05302
    A series of novel α-furfuryl-2-alkylaminophosphonates have been efficiently synthesized from the one-pot three-component classical Kabachnik-Fields reaction in a green chemical approach by addition of an in situ generated dialkylphosphite to Schiff's base of aldehydes and amines by using environmental and eco-friendly silica gel supported iodine as a catalyst by microwave irradiation. The advantage of this protocol is simplicity in experimental procedures and products were resulted in high isolated yields. The synthesized α-furfuryl-2-alkylaminophosphonates were screened to in vitro antioxidant and plant growth regulatory activities and some are found to be potent with antioxidant and plant growth regulatory activities. These in vitro studies have been further supported by ADMET (absorption, distribution, metabolism, excretion, and toxicity), quantitative structure-activity relationship, molecular docking, and bioactivity studies and identified that they were potentially bound to the GLN340 amino acid residue in chain C of 1DNU protein and TYR597 amino acid residue in chain A of 4M7E protein, causing potential exhibition of antioxidant and plant growth regulatory activities. Eventually, title compounds are identified as good blood-brain barrier (BBB)-penetrable compounds and are considered as proficient central nervous system active and neuroprotective antioxidant agents as the neuroprotective property is determined with BBB penetration thresholds.
    Matched MeSH terms: Microwaves
  11. Fulltext UWB Antenna with Enhanced Directivity for Applications in Microwave Medical Imaging
    Awan D, Bashir S, Khan S, Al-Bawri SS, Dalarsson M
    Sensors (Basel), 2024 Feb 18;24(4).
    PMID: 38400473 DOI: 10.3390/s24041315
    Microwave medical imaging (MMI) is experiencing a surge in research interest, with antenna performance emerging as a key area for improvement. This work addresses this need by enhancing the directivity of a compact UWB antenna using a Yagi-Uda-inspired reflector antenna. The proposed reflector-loaded antenna (RLA) exhibited significant gain and directivity improvements compared to a non-directional reference antenna. When analyzed for MMI applications, the RLA showed a maximum increase of 4 dBi in the realized gain and of 14.26 dB in the transmitted field strength within a human breast model. Moreover, it preserved the shape of time-domain input signals with a high correlation factor of 94.86%. To further validate our approach, another non-directional antenna with proven head imaging capabilities was modified with a reflector, achieving similar directivity enhancements. The combined results demonstrate the feasibility of RLAs for improved performance in MMI systems.
    Matched MeSH terms: Microwaves*
  12. New One-Pot Synthesis of 1,3,5-Triazines: Three-Component Condensation, Dimroth Rearrangement, and Dehydrogenative Aromatization
    Junaid A, Lim FPL, Tiekink ERT, Dolzhenko AV
    ACS Comb Sci, 2019 07 08;21(7):548-555.
    PMID: 31180634 DOI: 10.1021/acscombsci.9b00079
    A new, effective one-pot synthesis of the 6, N2-diaryl-1,3,5-triazine-2,4-diamines under microwave irradiation was developed. The method involved an initial three-component condensation of cyanoguanidine, aromatic aldehydes, and arylamines in the presence of hydrochloric acid. Without isolation, the resulting 1,6-diaryl-1,6-dihydro-1,3,5-triazine-2,4-diamines were treated with a base to initiate Dimroth rearrangement and spontaneous dehydrogenative aromatization, affording the desired compounds. The developed method was found to be sufficiently general in scope, tolerating various aromatic aldehydes and amines; by using their combinations in the first step, a representative library of 110 compounds was successfully prepared and screened for anticancer properties.
    Matched MeSH terms: Microwaves
  13. 3,4-Diaminopyrazolo[3,4-d]pyrimidines: a new three-component microwave-assisted synthesis and anti-leukemic properties
    Ng JH, Lim FPL, Tiekink ERT, Dolzhenko AV
    Org Biomol Chem, 2023 Apr 26;21(16):3432-3446.
    PMID: 37039282 DOI: 10.1039/d3ob00350g
    A convenient method for the synthesis of N3,N4-disubstituted 3,4-diaminopyrazolo[3,4-d]pyrimidines was developed using a three-component reaction of 3,5-diaminopyrazole-4-carbonitriles with primary amines and orthoesters. The preparation of 116 examples demonstrated the good scope of the reaction, which tolerated variations in the substrate structure and was particularly efficient under microwave irradiation. The short reaction time and chromatography-free product isolation add practicality to this method. The anti-leukemic activity was assessed in vitro using K562 and Jurkat T cells, and the selectivity of the most active compounds was evaluated using non-cancerous MRC5 cells. The most promising compound inhibited Jurkat T cells with a GI50 value of 0.5 μM and a selectivity index of 65.
    Matched MeSH terms: Microwaves*
  14. Fulltext Preparation of Lignan-Rich Extract from the Aerial Parts of Phyllanthus niruri Using Nonconventional Methods
    Meselhy MR, Abdel-Sattar OE, El-Mekkawy S, El-Desoky AM, Mohamed SO, Mohsen SM, et al.
    Molecules, 2020 Mar 05;25(5).
    PMID: 32151037 DOI: 10.3390/molecules25051179
    Phyllanthin and related lignans were found to be responsible, at least in part, for most of the activity of Phyllanthus species. This observation encouraged the authors to develop methods for the preparation of an extract rich in phyllanthin and related lignans from the aerial parts of P. niruri L. Direct extraction with solvents produced extracts with variable yields and contents of lignans. Lignans were identified by LC-ESI-MS analysis as phyllanthin (used as marker substance), hypophyllanthin, phylltetralin, nirtetralin, and niranthin. Extraction with boiling water produced 18.10 g% (w/w) extract with a trace amount of lignans (phyllanthin content of 0.33 ± 0.10 mg/g extract), while extraction with MeOH gave 3.6 g% w/w extract with a low phyllanthin content (3.1 mg/g extract), as determined by HPLC. However, Soxhlet extraction with hexane, CH2Cl2, or acetone gave extracts with low yields (0.82, 1.12, and 3.40 g% w/w, respectively) and a higher phyllanthin contents (36.2 ± 2.6, 11.7 ± 1.68, and 11.7 ± 1.10 mg/g extract, respectively). Extraction quality and efficiency were optimized by adopting the following three different approaches: (1) Alkaline digestion of the plant material with 30% potassium hydroxide yielded 3.1 g% w/w of purified extract with high phyllanthin content (22.34 ± 0.13 mg/g); (2) microwave-assisted extraction using 80% MeOH gave an extract with a better yield (8.13 g% w/w) and phyllanthin content (21.2 ± 1.30 mg/g) (after filtration through a Diaion HP-20 column); and (3) treatment of the ground plant material at 50 °C with two hydrolytic enzymes, cellulase (9 U/g for 12 h) and then, protease (4 U/g up to 72 h) optimized the yield of extract (13.92 g% w/w) and phyllanthin content (25.9 mg/g extract and total lignans content of 85.87 mg/g extract). In conclusion, the nonconventional methods presented here are superior for optimizing the yield of extract and its lignan contents from the aerial parts of P. niruri.
    Matched MeSH terms: Microwaves
  15. Fulltext A Study on Microwave Absorption Properties of Carbon Black and Ni0.6Zn0.4Fe2O4 Nanocomposites by Tuning the Matching-Absorbing Layer Structures
    Ibrahim IR, Matori KA, Ismail I, Awang Z, Rusly SNA, Nazlan R, et al.
    Sci Rep, 2020 Feb 21;10(1):3135.
    PMID: 32081972 DOI: 10.1038/s41598-020-60107-1
    Microwave absorption properties were systematically studied for double-layer carbon black/epoxy resin (CB) and Ni0.6Zn0.4Fe2O4/epoxy resin (F) nanocomposites in the frequency range of 8 to 18 GHz. The Ni0.6Zn0.4Fe2O4 nanoparticles were synthesized via high energy ball milling with subsequent sintering while carbon black was commercially purchased. The materials were later incorporated into epoxy resin to fabricate double-layer composite structures with total thicknesses of 2 and 3 mm. The CB1/F1, in which carbon black as matching and ferrite as absorbing layer with each thickness of 1 mm, showed the highest microwave absorption of more than 99.9%, with minimum reflection loss of -33.8 dB but with an absorption bandwidth of only 2.7 GHz. Double layer absorbers with F1/CB1(ferrite as matching and carbon black as absorbing layer with each thickness of 1 mm) structure showed the best microwave absorption performance in which more than 99% microwave energy were absorbed, with promising minimum reflection loss of -24.0 dB, along with a wider bandwidth of 4.8 GHz and yet with a reduced thickness of only 2 mm.
    Matched MeSH terms: Microwaves
  16. Fulltext Consumption of Manjakani among postpartum mothers and risk of heavy metal contamination
    Normina Ahmad Bustami, Yu Bin Ho, Chung Keat Tan, Ahmad Zaharin Aris, Eugenie Sin Sing Tan
    Malaysian Journal of Medicine and Health Sciences, 2020;16(2):75-82.
    MyJurnal
    Introduction: In Malaysia, herbal medicines are used for variety of reasons including health promotion and home remedies during pregnancy and postpartum with Manjakani (Quercus infectoria) as one of the most commonly consumed herbs. Herbal medicines consumption had been linked to heavy metals contamination and transfer from mother to infant and may affect infant’s growth and development. This study aims to (i) determine Manjakani consumption among postpartum mothers, (ii) quantify its heavy metals level, namely lead, cadmium, arsenic and chromium, and (iii) determine health risk associated with its consumption. Methods: A cross-sectional study involving 106 postpartum mothers was carried out in Kuala Lumpur. Six samples of Manjakani were sampled and extracted using microwave digester and analysed using Inductively coupled plasma mass spectrometry (ICP-MS). Non-carcinogenic health risks for herbal medicine consumption were calculated using Hazard Quotient (HQ). Results: Manjakani was consumed by 16% of mothers (n=17). Highest level of the metals was shown by chromium with mean concentration of 4210 ± 1910 ug/kg, followed by lead (170.8 ± 193.2), arsenic (39.3 ± 27.1) and cadmium (7.7 ± 0.76). There were no significant non-carcinogenic health risks with lead, arsenic, chromium and cadmium contamination (HQ < 1). Conclusion: Manjakani is consumed by mothers during confinement period. Heavy metals were quantified in Manjakani although no significant association was observed with socio-demographic characteristics and birth outcomes.
    Matched MeSH terms: Microwaves
  17. Fulltext Heavy metals in Danggui (Angelica sinensis) consumed by postpartum mothers and its health risk
    Normina Ahmad Bustami, Yu Bin Ho, Chung Keat Tan, Ahmad Zaharin Aris, Eugenie Sin Sing Tan
    Malaysian Journal of Medicine and Health Sciences, 2020;16(3):113-117.
    MyJurnal
    Introduction: Consumption of Chinese Herbal Medicine (CHMs) have escalated globally. They are preferred treat- ment for minor diseases or disorders. In Malaysia, CHMs are common home remedies during pregnancy and postpar- tum. Angelica sinensis (Danggui) is a staple CHMs during postpartum for purpose of nourishing blood and resolving stasis. Concerns are raised over possible heavy metals toxicity. Objective: This study aims to (i) determine Danggui consumption among postpartum mothers, (ii) quantify its heavy metals level, namely Lead (Pb), Cadmium (Cd), Ar- senic (As) and Chromium (Cr) and (iii) determine health risks of Danggui consumption among mothers. Methods: A cross-sectional study involving 112 postpartum mothers was carried out in Kuala Lumpur. Danggui samples were collected from nine districts in Kuala Lumpur (Segambut, Seputeh, Cheras, Kepong, Bandar Tun Razak, Titiwangsa, Setiawangsa, Batu and Lembah Pantai). Heavy metals were extracted using microwave digester and analysed using Inductively coupled plasma mass spectrometry (ICPMS). Hazard Quotient (HQ) was used to determine non-carcino- genic health risks for herbal medicine consumption. Results: Danggui was consumed by 19.6% of mothers (n=22). Among them, incidence of jaundice was 63.6% and need for phototherapy was 40.9%. Heavy metals contamina- tions were found in the decreasing order of Cr > As > Pb > Cd with median (interquartile) of 3996.3 (2805.6) μg/ kg, 128.3 (56.7), 98.6 (99.1) and 37.0 (35.0) respectively. No non-carcinogenic health risks were found for all four metals. Conclusion: Alarming concentrations of heavy metals were quantified in Danggui warranting for further in- vestigation to safeguard health of postpartum mothers.
    Matched MeSH terms: Microwaves
  18. Fulltext The Pertinence of Microwave Irradiated Coconut Shell Bio-Sorbent for Wastewater Decolourization: Structural Morphology and Adsorption Optimization Using the Response Surface Method (RSM)
    Abdulsalam M, Che Man H, Isma Idris A, Zainal Abidin Z, Faezah Yunos K
    Int J Environ Res Public Health, 2018 10 09;15(10).
    PMID: 30304814 DOI: 10.3390/ijerph15102200
    Palm oil mill effluent contains carcinogenic coloured compounds that are difficult to separate due to their aromatic structure. Though colour treatment using adsorption processes at lower pH (<4) have been reported effectual, due to its acidity the remediated effluent poses an environmental hazard as a result. Thus, the current study focused on achieving decolourization at neutral pH by enhancing the morphology of the coconut shell activated carbon (CSAC) using N₂ as activating-agent with microwave irradiation heating. The microwave pretreated and non-pretreated CSAC were characterized using scanned electron microscopy (SEM), energy dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) analysis. A significant modification in the porous structure with a 66.62% increase in the specific surface area was achieved after the pretreatment. The adsorption experimental matrix was developed using the central composite design to investigate the colour adsorption performance under varied pH (6⁻7), dosage (2⁻6 g) and contact time (10⁻100 min). At optimum conditions of neutral pH (7), 3.208 g dosage and contact time of 35 min, the percentage of colour removal was 96.29% with negligible differences compared with the predicted value, 95.855%. The adsorption equilibrium capacity of 1430.1 ADMI × mL/g was attained at the initial colour concentration of 2025 ADMI at 27 °C. The experimental data fitted better with the Freundlich isotherm model with R² 0.9851.
    Matched MeSH terms: Microwaves*
  19. Fulltext Dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands
    Islam MM, Islam MT, Faruque MR
    ScientificWorldJournal, 2013;2013:378420.
    PMID: 24385878 DOI: 10.1155/2013/378420
    The dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands is presented. The fabrication of the proposed antenna is performed with slots and a Duroid 5870 dielectric substrate and is excited by a 50 Ω microstrip transmission line. A high-frequency structural simulator (HFSS) is used which is based on the finite element method (FEM) in this research. The measured impedance bandwidth (2 : 1 VSWR) achieved is 1.07 GHz (15.93 GHz-14.86 GHz) on the lower band and 0.94 GHz (20.67-19.73 GHz) on the upper band. A stable omnidirectional radiation pattern is observed in the operating frequency band. The proposed prototype antenna behavior is discussed in terms of the comparisons of the measured and simulated results.
    Matched MeSH terms: Microwaves*
  20. Fulltext A Near-Zero Refractive Index Meta-Surface Structure for Antenna Performance Improvement
    Ullah MH, Islam MT, Faruque MRI
    Materials (Basel), 2013 Nov 06;6(11):5058-5068.
    PMID: 28788376 DOI: 10.3390/ma6115058
    A new meta-surface structure (MSS) with a near-zero refractive index (NZRI) is proposed to enhance the performance of a square loop antenna array. The main challenge to improve the antenna performance is increment of the overall antenna volume that is mitigated by assimilating the planar NZRI MSS at the back of the antenna structure. The proposed NZRI MSS-loaded CPW-fed (Co-Planar Waveguide) four-element array antenna is designed on ceramic-bioplastic-ceramic sandwich substrate using high-frequency structure simulator (HFSS), a finite-element-method-based simulation tool. The gain and directivity of the antenna are significantly enhanced by incorporating the NZRI MSS with a 7 × 6 set of elements at the back of the antenna structure. Measurement results show that the maximum gains of the antenna increased from 6.21 dBi to 8.25 dBi, from 6.52 dBi to 9.05 dBi and from 10.54 dBi to 12.15 dBi in the first, second and third bands, respectively. The effect of the slot configuration in the ground plane on the reflection coefficient of the antenna was analyzed and optimized. The overall performance makes the proposed antenna appropriate for UHFFM (Ultra High Frequency Frequency Modulation) telemetry-based space applications as well as mobile satellite, microwave radiometry and radio astronomy applications.
    Matched MeSH terms: Microwaves
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