Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 5

Search results for: Sudarat Khwan-On

5 Visible-Light Induced Photocatalytic Degradation of Dye Molecules over ZnWO4-Bi2WO6 Composite

Authors: Sudarat Issarapanacheewin, Katcharin Wetchakun, Sukon Phanichphant, Wiyong Kangwansupamonkon, Natda Wetchakun


The photocatalytic degradation of Methylene blue (MB) and Rhodamine B (RhB) in the presence of ZnWO4-Bi2WO6 composite under visible light irradiation (λ ≥ 400 nm) were studied in this research. The structural and photophysical properties of ZnWO4-Bi2WO6 composite on the photocatalytic degradation process were investigated. The as-prepared ZnWO4-Bi2WO6 composite photocatalyst exhibits wide absorption in the visible-light region and display superior visible-light-driven photocatalytic activities in degradation of MB and RhB. The enhanced photocatalytic activity was attributed to electron-hole separation with the appropriate band potential and the physicochemical properties of ZnWO4 and Bi2WO6. The main active species for the degradation of organic dyes were investigated to explain the enhancement of photocatalytic performance of ZnWO4-Bi2WO6 composite. The possible photocatalytic degradation pathway of aqueous MB and RhB dyes and charge transfer of ZnWO4-Bi2WO6 composite was proposed.

Keywords: composite, dyes, photocatalytic activity, ZnWO4-Bi2WO6

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4 A High Step-Up DC-DC Converter for Renewable Energy System Applications

Authors: Sopida Vacharasukpo, Sudarat Khwan-On


This paper proposes a high step-up DC-DC converter topology for renewable energy system applications. The proposed converter employs only a single power switch instead of using several switches. Compared to the conventional DC-DC step-up converters the higher voltage gain with small output ripples can be achieved by using the proposed high step-up DC-DC converter topology. It can step up the low input voltage (20-50Vdc) generated from the photovoltaic modules to the high output voltage level approximately 600Vdc in order to supply the three-phase inverter fed the three-phase motor drive. In this paper, the operating principle of the proposed converter topology and its control strategy under the continuous conduction mode (CCM) are described. Finally, simulation results are shown to demonstrate the effectiveness of the proposed high step-up DC-DC converter with its control strategy to increase the voltage step-up conversion ratio.

Keywords: DC-DC converter, high step-up ratio, renewable energy, single switch

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3 Characteristics of Rectus Femoris and Physical Performance Between Adults and Elderly

Authors: Sudarat Apibantaweesakul, Poonyanat Nualon, Piyasiri Ngamsangiam, Vinitha Puengtanom, Plaiwan Suttanon


The rectus femoris (RF) is important as a biomarker for physical disability and capacity related to age decline. Sarcopenia in elderly people is typically defined with essential criteria of low muscle mass, low muscle strength, and poor physical performance. Characteristics of muscle ultrasound image provide the qualitative and quantitative features of muscle, including muscle thickness (MT), cross-sectional area (CSA), echo intensity (EI) for early diagnosis of sarcopenia. Understanding the coverage of RF morphological characteristics and physical performance from young adults to older people may gain a better understanding of degenerative change. The present study aimed to examine RF characteristics and physical performance changes induced by the advanced age. The study employed a cross-sectional design. A total of 45 healthy participants were recruited to the study (30 adults and 15 elderly). The RF morphological characteristics, including MT, CSA, and EI, were measured using a B-mode ultrasonographic apparatus (Toshiba, Xario 100 MX EDITION). Physical performances, including knee extension strength (KES), five times sit to stand test (FTSST), and timed up and go test (TUG) also assessed. Then statistical analyses for correlation analyses and comparisons among groups were performed. Body height, RF size (thickness and cross-sectional area), and KES were negatively correlated with age. While EI, FTSST, and TUG were positively correlated with age. Body mass showed a positive association with RF size (MT and CSA) and KES. The correlation between MT and CSA was found in RF. Additionally, MT and CSA were negatively correlated with subcutaneous adipose tissue (SAT), EI, FTSST, and TUG, while positive correlations between RF size and KES were found. For comparison results, there were significant differences of body height; RF morphological characteristics (including normalized MT and CSA, and EI); normalized KES; and physical performance (FTSST, and TUG) between young adults and elderly. These parameters were found to be significantly decreased in the elderly than young adults except EI. Age-related RF morphological features and physical performances could represent the degenerative changes in the elderly. These findings supported that body mass is a crucial body dimension parameter for the normalization of RF size and its strength. Moreover, subcutaneous adipose tissue should be considered for declining RF size with Increasing age. These could help for monitoring health and performance as well as for emphasizing the related RF exercise in the elderly.

Keywords: aging, echo intensity, physical performance, ultrasonography

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2 Falls, Physical and Cognitive Performance among Young, Middle-Aged and Older People

Authors: Plaiwan Suttanon, Piyasiri Ngamsangiam, Sudarat Apibantaweesakul


Falls are considered as one of the major issue in an aging society that lead to impairments of physical and mental functions. A related study reported that falls increased with age. Advanced age would decrease physical and cognitive performance, which possibly develop to be several recognized falls risk factors in older people. Identified risk factors of falls, including chronic conditions, medications used, physical activity, and physiological changes, were reported with increasing falls rate from the middle adults. Falls and falls risk factors in older people have been extensively reported; however, there are a limited number of studies investigated falls and possible physical or cognitive falls risk factors in people with age-range covering from young to old age. To gain a better understanding for falls characteristics and falls risk factors from young adults to old adults. The aim of this study was to evaluate differences of falls, physical performance, and cognitive performance related to falls among young (20- 44 years), middle-aged (45- 60 years), and older (>60 years). The study design was a cross-sectional observation. One hundred and sixty-two community-dwelling people participated in this study. The participants were divided into three groups according to their age: young (29.44±6.03 years, n = 52); middle-aged (51.06±4.51 years, n = 52); and older (71.34±6.95, n = 58). Falls (history, perceived causes, characteristics); physical performance (including muscle strength, balance, proprioception, and flexibility); and cognitive performance using the Mini-Mental State Examination (MMSE) were assessed. The reporting of falls in the previous year were not significantly different among the three groups (young 50%, middle-aged 65.4%, and older 58.6%). There were differences across the three groups in perceived causes of falls (young; specific activities, slippery, missed a step), (middle-aged; slippery, dizzy, missed a step), and (older; dizzy, stumping on objects, slippery). Falls directions were reported in forward and side directions in young adults, while forward and backward were found in middle-aged and older. Falls risk factors, including cognitive performance, physical performance (strength, balance, proprioception, and flexibility), declined with age. However, there were no significant differences between young adults and middle-aged in handgrip strength, knee extensor strength, knee proprioception at 60-degree, and ankle flexibility except active ankle plantarflexion. Falls and falls risk factors were found with increased age. Since middle-aged, several falls risk factors commence to change, and these include both physical and cognitive performance. These findings also supported that the specified falls characteristics (perceived causes of falls and falls direction) were found in each age range. This would raise awareness in falls and falls risk factors in each stage of life, as well as in preparing falls management in order to prevent falls in the latter years. Falls prevention recommended for the middle-aged adults focusing on balance and mobility abilities.

Keywords: adults, aging, falls, risk factors

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1 Extraction of Rice Bran Protein Using Enzymes and Polysaccharide Precipitation

Authors: Sudarat Jiamyangyuen, Tipawan Thongsook, Riantong Singanusong, Chanida Saengtubtim


Rice is a staple food as well as exported commodity of Thailand. Rice bran, a 10.5% constituent of rice grain, is a by-product of rice milling process. Rice bran is normally used as a raw material for rice bran oil production or sold as feed with a low price. Therefore, this study aimed to increase value of defatted rice bran as obtained after extracting of rice bran oil. Conventionally, the protein in defatted rice bran was extracted using alkaline extraction and acid precipitation, which results in reduction of nutritious components in rice bran. Rice bran protein concentrate is suitable for those who are allergenic of protein from other sources eg. milk, wheat. In addition to its hypoallergenic property, rice bran protein also contains good quantity of lysine. Thus it may act as a suitable ingredient for infant food formulations while adding variety to the restricted diets of children with food allergies. The objectives of this study were to compare properties of rice bran protein concentrate (RBPC) extracted from defatted rice bran using enzymes together with precipitation step using polysaccharides (alginate and carrageenan) to those of a control sample extracted using a conventional method. The results showed that extraction of protein from rice bran using enzymes exhibited the higher protein recovery compared to that extraction with alkaline. The extraction conditions using alcalase 2% (v/w) at 50 C, pH 9.5 gave the highest protein (2.44%) and yield (32.09%) in extracted solution compared to other enzymes. Rice bran protein concentrate powder prepared by a precipitation step using alginate (protein in solution: alginate 1:0.006) exhibited the highest protein (27.55%) and yield (6.62%). Precipitation using alginate was better than that of acid. RBPC extracted with alkaline (ALK) or enzyme alcalase (ALC), then precipitated with alginate (AL) (samples RBP-ALK-AL and RBP-ALC-AL) yielded the precipitation rate of 75% and 91.30%, respectively. Therefore, protein precipitation using alginate was then selected. Amino acid profile of control sample, and sample precipitated with alginate, as compared to casein and soy protein isolated, showed that control sample showed the highest content among all sample. Functional property study of RBP showed that the highest nitrogen solubility occurred in pH 8-10. There was no statically significant between emulsion capacity and emulsion stability of control and sample precipitated by alginate. However, control sample showed a higher of foaming and lower foam stability compared to those of sample precipitated with alginate. The finding was successful in terms of minimizing chemicals used in extraction and precipitation steps in preparation of rice bran protein concentrate. This research involves in a production of value-added product in which the double amount of protein (28%) compared to original amount (14%) contained in rice bran could be beneficial in terms of adding to food products eg. healthy drink with high protein and fiber. In addition, the basic knowledge of functional property of rice bran protein concentrate was obtained, which can be used to appropriately select the application of this value-added product from rice bran.

Keywords: alginate, carrageenan, rice bran, rice bran protein

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