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Sample records for bioelectrical impedance analysis

  1. Bioelectrical impedance analysis--part I

    DEFF Research Database (Denmark)

    Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D;

    2004-01-01

    The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant...... of the estimate. The determination of changes in body cell mass (BCM), extra cellular (ECW) and intra cellular water (ICW) requires further research using a valid model that guarantees that ECW changes do not corrupt the ICW. The use of segmental-BIA, multifrequency BIA, or bioelectrical spectroscopy in altered...

  2. BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS IDENTIFIES SARCOPENIA IN NURSING HOME RESIDENTS

    Science.gov (United States)

    Loss of muscle mass and water shifts between body compartments are contributing factors to frailty in the elderly. The body composition changes are especially pronounced in institutionalized elderly. We investigated the ability of single-frequency bioelectrical impedance analysis (BIA) to identify b...

  3. Bioelectrical impedance analysis of bovine milk fat

    International Nuclear Information System (INIS)

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  4. Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men.

    Science.gov (United States)

    Rodríguez-Rodríguez, Fernando; Cristi-Montero, Carlos; González-Ruíz, Katherine; Correa-Bautista, Jorge Enrique; Ramírez-Vélez, Robinson

    2016-01-01

    Muscle strength can define the general muscular fitness (MF) measurable through hand-grip strength (HG), which is a factor that relates to the health of people of different ages. In this study we evaluated the muscle strength together with a bioimpedance electric analysis in 223 healthy Colombian adult subjects. The bioelectrical impedance vector analysis (BIVA) was conducted to determine the resistance (R), reactance (Xc) and phase angle (PhA). We classified the subjects into three groups (for tertiles), obtaining lower values of R and Xc in subjects with lower HG, plus a high correlation between PhA and HG. An increase in the level of PhA is associated with a high level of MF in a sample of healthy Latin American adult men. The BIVA's parameters and PhA are a potentially effective preventive measure to be integrated into routine screening in the clinical setting. PMID:27384579

  5. Bioelectrical Impedance Vector Analysis and Muscular Fitness in Healthy Men

    Directory of Open Access Journals (Sweden)

    Fernando Rodríguez-Rodríguez

    2016-07-01

    Full Text Available Muscle strength can define the general muscular fitness (MF measurable through hand-grip strength (HG, which is a factor that relates to the health of people of different ages. In this study we evaluated the muscle strength together with a bioimpedance electric analysis in 223 healthy Colombian adult subjects. The bioelectrical impedance vector analysis (BIVA was conducted to determine the resistance (R, reactance (Xc and phase angle (PhA. We classified the subjects into three groups (for tertiles, obtaining lower values of R and Xc in subjects with lower HG, plus a high correlation between PhA and HG. An increase in the level of PhA is associated with a high level of MF in a sample of healthy Latin American adult men. The BIVA’s parameters and PhA are a potentially effective preventive measure to be integrated into routine screening in the clinical setting.

  6. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management

    OpenAIRE

    Ahyoung Choi; Justin Younghyun Kim; Seongwook Jo; Jae Hwan Jee; Heymsfield, Steven B.; Bhagat, Yusuf A.; Insoo Kim; Jaegeol Cho

    2015-01-01

    Current bioelectric impedance analysis (BIA) systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz) with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA) system (GE Lunar Prodigy, GE Healthcare, Buckingha...

  7. Bioelectrical impedance analysis as a laboratory activity: At the interface of physics and the body

    Science.gov (United States)

    Mylott, Elliot; Kutschera, Ellynne; Widenhorn, Ralf

    2014-05-01

    We present a novel laboratory activity on RC circuits aimed at introductory physics students in life-science majors. The activity teaches principles of RC circuits by connecting ac-circuit concepts to bioelectrical impedance analysis (BIA) using a custom-designed educational BIA device. The activity shows how a BIA device works and how current, voltage, and impedance measurements relate to bioelectrical characteristics of the human body. From this, useful observations can be made including body water, fat-free mass, and body fat percentage. The laboratory is engaging to pre-health and life-science students, as well as engineering students who are given the opportunity to observe electrical components and construction of a commonly used biomedical device. Electrical concepts investigated include alternating current, electrical potential, resistance, capacitance, impedance, frequency, phase shift, device design, and the use of such topics in biomedical analysis.

  8. Evaluation of Bioelectrical Impedance Analysis for Identifying Overweight Individuals at Increased Cardiometabolic Risk: A Cross-Sectional Study

    OpenAIRE

    Lamb, Maxine J. E.; Byrne, Christopher D.; Wilson, James F; Wild, Sarah H.

    2014-01-01

    OBJECTIVE: To investigate whether bioelectrical impedance analysis could be used to identify overweight individuals at increased cardiometabolic risk, defined as the presence of metabolic syndrome and/or diabetes.DESIGN AND METHODS: Cross-sectional study of a Scottish population including 1210 women and 788 men. The diagnostic performance of thresholds of percentage body fat measured by bioelectrical impedance analysis to identify people at increased cardiometabolic risk was assessed using re...

  9. Feasibility of bioelectrical impedance analysis in children with a severe generalized cerebral palsy

    OpenAIRE

    Veugelers, Rebekka; Penning, Corine; van Gulik, Laura; Tibboel, Dick; Evenhuis, Heleen

    2006-01-01

    textabstractObjective: The need is strong for an accurate and easy-to-perform test to evaluate the nutritional state of children who have a severe generalized cerebral palsy, defined as a severe motor handicap and an intellectual disability. For that purpose, we determined the feasibility of bioelectrical impedance analysis (BIA) in these children and evaluated their nutritional state. Methods: BIA recordings were done in 35 children who had a severe generalized cerebral palsy using a single-...

  10. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets

    OpenAIRE

    Langer, Raquel D.; Borges, Juliano H.; Pascoa, Mauro A.; Cirolini, Vagner X.; Gil Guerra-Júnior; Ezequiel M. Gonçalves

    2016-01-01

    Background: Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM est...

  11. Use of bioelectrical impedance analysis to determine body composition changes in HIV-associated wasting.

    Science.gov (United States)

    Klauke, Stephan; Fischer, Harald; Rieger, Armin; Frühauf, Lukas; Staszewski, Schlomo; Althoff, Peter-Henning; Helm, Eilke Brigitte

    2005-04-01

    AIDS wasting syndrome results in loss of lean body mass and body cell mass. This 12-week, open-label study used bioelectrical impedance analysis to measure body composition changes in 24 patients with AIDS wasting syndrome receiving recombinant human growth hormone (r-hGH). The primary endpoint was percentage monthly change in body weight before/after r-hGH. Secondary endpoints included change from baseline in body composition (bioelectrical impedance analysis), isometric strength and CD4+ count. Twenty patients completed the study: r-hGH resulted in mean weight gains (+2.7%, P = 0.146), and significant increases in mean body cell mass (+8.0%, P = 0.0211), lean body mass (+4.8%, P = 0.0373) and water (+5.5%, P r-hGH was generally well tolerated; the most frequent adverse events were fever (7.3%) and diarrhoea (6.3%). Thus, bioelectrical impedance analysis can detect improved body cell mass independent of changes in body weight resulting from r-hGH treatment in patients with AIDS wasting syndrome.

  12. Bioelectrical impedance analysis for the prediction of hot carcass weight in buffalo calf

    Directory of Open Access Journals (Sweden)

    Leopoldo Iannuzzi

    2010-01-01

    Full Text Available Twenty young buffalo male calves were fed ad libitum with a total mix ration and with vitamin-mineral integration for 14 months. Seven days before slaughter, the animals were weighed and bioelectrical impedance measurements were collected in live animals. Physical and chemical characteristics were assessed on the Longissimus dorsi muscle after slaughter. Correlations and regression equations were calculated to determine the possible use of bioelectrical impedance for evaluating hot carcass weight. Bioelectrical impedance analysis at different frequencies, simple correlation and analysis of regression were examined for all the data collected, supporting the possibility of hot carcass weight prediction with equation at multifrequency. The results show that, probably due to the variability in animal live weight, the distribution of the colour parameters was not normally distributed. Moreover, using different frequencies of resistance and reactance, hot carcass weight in buffalo may be predicted with the following equation: Y=98.47–8.84(Rs100KHz+4.41(Rs1000 KHz-116.27(Xc5 KHz+51.04(Xc50 KHz+20.30(Xc100 KHz-33.92(Xc500 KHz+9.01(Xc1000 KHz±ε (Adjusted R Square value of .907 and SE of 5.728 However, further studies are required to improve the technique also in buffalo, after standardization of the method.

  13. Critical factors and their impact on bioelectrical impedance analysis in children

    DEFF Research Database (Denmark)

    Brantlov, Steven; Ward, Leigh C; Jødal, Lars;

    2016-01-01

    to BIA, highlights critical factors that may impact on BIA and identifies areas where there is a need for further research in order to increase the quality of impedance measurements and prediction of body composition in children. Although the results of this review highlights a lack of studies...... in children to provide definitive BIA guidelines, the technique has, however, still proven valuable for body composition assessment in ill and healthy children. To fill the gaps in our knowledge, future studies should focus on methodological issues, particularly with regard to hydration, voiding, clothing......Several guidelines for bioelectrical impedance analysis (BIA) have been prepared for adults, but not for children. For that reason, there is a pressing need to develop a consensus set of guidelines to facilitate standardisation of BIA in this important group. This review provides an introduction...

  14. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management.

    Science.gov (United States)

    Choi, Ahyoung; Kim, Justin Younghyun; Jo, Seongwook; Jee, Jae Hwan; Heymsfield, Steven B; Bhagat, Yusuf A; Kim, Insoo; Cho, Jaegeol

    2015-01-01

    Current bioelectric impedance analysis (BIA) systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz) with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA) system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK) and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea). In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC) in South Korea and the Pennington Biomedical Research Center (PBRC) in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p 0.728 (paired t-test), DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg). Thus, this portable BIA system shows a promising ability to estimate an individual's body composition that is comparable to large stationary BIA systems. PMID:26364636

  15. Analysis of body water compartments after a short sauna bath using bioelectric impedance analysis.

    Science.gov (United States)

    Servidio, M-F; Mohamed, E I; Maiolo, C; Hereba, A T; Perrone, F; Garofano, P; Iacopino, L

    2003-10-01

    Studies have suggested that long-term sauna bathing may lower blood pressure in persons with hypertension by causing a direct loss of extracellular water and plasma minerals. The objective of the present study was to evaluate the effect of short-term sauna bathing on body water compartments as estimated by bioelectric impedance analysis (BIA). We recruited 15 men [mean age (+/-SD) of 23.93+/-5.12 years and mean body mass index (BMI) of 23.25+/-2.84 kg/m(2)] and 10 women matched for age and BMI. Total body resistance, reactance, and impedance were measured for all participants using BIA, at baseline, after a short sauna bath, and after a rest period. Total, extracellular, and intracellular water compartments were calculated using BIA formulae. There were no significant differences for any of the body water compartments when comparing the measurements taken before and after the sauna bath and after the rest period. However, it remains to be determined whether or not BIA is sensitive to rapid changes in water volume.

  16. Tissue electrical properties measured by bioelectrical impedance analysis among healthy and sportsmen population

    Science.gov (United States)

    Kapica, Dominik; Warchulińska, Joanna; Jakubiak, Monika; Teter, Mariusz; Mlak, Radosław; Hałabiś, Magdalena; Wójcik, Waldemar; Małecka-Massalska, Teresa

    2015-09-01

    Introduction: Bioelectrical impedance analysis (BIA) is a useful tool to asses human body composition and nutrition status; multi-frequency BIA has a higher accuracy than single-frequency BIA. In our study a difference of impedance values (Z) at 5, 100 and 200 kHz and Z200/Z5 index between professional athletes and control group were determined. Methods: In this research 105 people were tested, divided into control group (72 people: 35 males and 37 females) and professional athletes (33 people: 16 males and 17 females). Impedance was measured at three frequency values - 5, 100 and 200 kHz; with received values the Z200/Z5 index was calculated. Results: In most compared subgroups impedance values showed significantly lower values in athletes than in control group (5 kHz - males: p=0.136, females: p=0.001, 100 kHz - males: p=0.039, females: pnutrition status and general health condition of athletes than in control group.

  17. Body Composition Comparison: Bioelectric Impedance Analysis with Dual-Energy X-Ray Absorptiometry in Adult Athletes

    Science.gov (United States)

    Company, Joe; Ball, Stephen

    2010-01-01

    The primary purpose of this study was to investigate the accuracy of the DF50 (ImpediMed Ltd, Eight Mile Plains, Queensland, Australia) bioelectrical impedance analysis device using dual-energy x-ray absorptiometry as the criterion in two groups: endurance athletes and power athletes. The secondary purpose was to develop accurate body fat…

  18. Body composition analysis in older adults with dementia. Anthropometry and bioelectrical impedance analysis: a critical review.

    Science.gov (United States)

    Camina Martín, M A; de Mateo Silleras, B; Redondo del Río, M P

    2014-11-01

    In clinical practice, geriatric nutritional assessment usually includes nutritional screening, a simple anthropometric assessment, measurement of various biochemical parameters, such as serum albumin, and sometimes (not always) body composition analysis (BCA). However, there is a high prevalence of undiagnosed malnutrition in patients with dementia. Several factors contribute to this situation; probably, the most notable is the methodology used to assess body composition (BC). In this regard, for BCA, techniques are needed that are noninvasive, affordable, safe, simple and that require the minimum possible collaboration by the elderly patient. Consequently, body mass index (BMI) and waist circumference (WC) are widely used as indicators of overall and central adiposity, respectively; however, there is no consensus on the cutoffs for the elderly, and changes in BC (especially muscle-mass depletion) are masked by normal values of BMI and WC. Bioimpedance analysis is a simple, cost-effective and precise method for BCA, provided that cross-validated equations are used. Its main disadvantage is that it is highly sensitive to changes in body water (overhydration or dehydration), leading to substantial errors in BC estimates. However, using Bioelectrical Impedance Vector Analysis errors are minimized, as there is no need for the subject to be normally hydrated and it does not require the use of predictive models. PMID:25117995

  19. Validation of bioelectrical-impedance analysis as a measurement of change in body composition in obesity

    International Nuclear Information System (INIS)

    The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition

  20. Validation of bioelectrical-impedance analysis as a measurement of change in body composition in obesity

    Energy Technology Data Exchange (ETDEWEB)

    Kushner, R.F.; Kunigk, A.; Alspaugh, M.; Andronis, P.T.; Leitch, C.A.; Schoeller, D.A. (Univ. of Chicago, IL (USA))

    1990-08-01

    The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition.

  1. Bioelectrical Impedance Assessment of Wound Healing

    OpenAIRE

    Lukaski, Henry C.; Moore, Micheal

    2012-01-01

    Objective assessment of wound healing is fundamental to evaluate therapeutic and nutritional interventions and to identify complications. Despite availability of many techniques to monitor wounds, there is a need for a safe, practical, accurate, and effective method. A new method is localized bioelectrical impedance analysis (BIA) that noninvasively provides information describing cellular changes that occur during healing and signal complications to wound healing. This article describes the ...

  2. Lipid and moisture content modeling of amphidromous Dolly Varden using bioelectrical impedance analysis

    Science.gov (United States)

    Stolarski, J.T.; Margraf, F.J.; Carlson, J.G.; Sutton, T.M.

    2014-01-01

    The physiological well-being or condition of fish is most commonly estimated from aspects of individual morphology. However, these metrics may be only weakly correlated with nutritional reserves stored as lipid, the primary form of accumulated energy in fish. We constructed and evaluated bioelectrical impedance analysis (BIA) models as an alternative method of assessing condition in amphidromous Dolly Varden Salvelinus malma collected from nearshore estuarine and lotic habitats of the Alaskan Arctic. Data on electrical resistance and reactance were collected from the lateral and ventral surfaces of 192 fish, and whole-body percent lipid and moisture content were determined using standard laboratory methods. Significant inverse relationships between temperature and resistance and reactance prompted the standardization of these data to a constant temperature using corrective equations developed herein. No significant differences in resistance or reactance were detected among spawning and nonspawning females after accounting for covariates, suggesting that electrical pathways do not intersect the gonads. Best-fit BIA models incorporating electrical variables calculated from the lateral and ventral surfaces produced the strongest associations between observed and model-predicted estimates of proximate content. These models explained between 6% and 20% more of the variability in laboratory-derived estimates of proximate content than models developed from single-surface BIA data and 32% more than models containing only length and weight data. While additional research is required to address the potential effects of methodological variation, bioelectrical impedance analysis shows promise as a way to provide high-quality, minimally invasive estimates of Dolly Varden lipid or moisture content in the field with only small increases in handling time.

  3. Smartphone-Based Bioelectrical Impedance Analysis Devices for Daily Obesity Management

    Directory of Open Access Journals (Sweden)

    Ahyoung Choi

    2015-09-01

    Full Text Available Current bioelectric impedance analysis (BIA systems are often large, cumbersome devices which require strict electrode placement on the user, thus inhibiting mobile capabilities. In this work, we developed a handheld BIA device that measures impedance from multiple frequencies (5 kHz~200 kHz with four contact electrodes and evaluated the BIA device against standard body composition analysis systems: a dual-energy X-ray absorptiometry (DXA system (GE Lunar Prodigy, GE Healthcare, Buckinghamshire, UK and a whole-body BIA system (InBody S10, InBody, Co. Ltd, Seoul, Korea. In the study, 568 healthy participants, varying widely in body mass index, age, and gender, were recruited at two research centers: the Samsung Medical Center (SMC in South Korea and the Pennington Biomedical Research Center (PBRC in the United States. From the measured impedance data, we analyzed individual body fat and skeletal muscle mass by applying linear regression analysis against target reference data. Results indicated strong correlations of impedance measurements between the prototype pathways and corresponding InBody S10 electrical pathways (R = 0.93, p < 0.0001. Additionally, body fat estimates from DXA did not yield significant differences (p > 0.728 (paired t-test, DXA mean body fat 29.45 ± 10.77 kg, estimated body fat 29.52 ± 12.53 kg. Thus, this portable BIA system shows a promising ability to estimate an individual’s body composition that is comparable to large stationary BIA systems.

  4. Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

    Science.gov (United States)

    de Blasio, Francesca; de Blasio, Francesco; Miracco Berlingieri, Giulia; Bianco, Andrea; La Greca, Marta; Franssen, Frits M E; Scalfi, Luca

    2016-01-01

    Background Multifrequency bioelectrical impedance analysis (MF-BIA) is a technique that measures body impedance (Z) at different frequencies (5, 10, 50, 100, and 250 kHz). Body composition may be estimated using empirical equations, which include BIA variables or, alternatively, raw BIA data may provide direct information on water distribution and muscle quality. Objectives To compare raw MF-BIA data between COPD patients and controls and to study their relationship with respiratory and functional parameters in COPD patients. Methods MF-BIA was performed (Human Im-Touch analyzer) in 212 COPD patients and 115 age- and BMI-matched controls. Fat-free mass (FFM) and fat mass were estimated from BIA data, and low- to high-frequency (5 kHz/250 kHz) impedance ratio was calculated. Physical fitness, lung function and respiratory muscle strength were also assessed in COPD patients. Results After adjusting for age, weight, and body mass index, FFM and the 5/250 impedance ratio were lower in COPD patients (P<0.001) and were negatively affected by disease severity. In both male and female patients, the 5/250 impedance ratio was significantly correlated mainly with age (r=−0.316 and r=−0.346, respectively). Patients with a 5/250 impedance ratio below median value had lower handgrip strength (P<0.001), 6-minute walk distance (P<0.005), respiratory muscle strength (P<0.005), forced expiratory volume in 1 second (P<0.05) and vital capacity (P<0.005). Finally, the 5/250 impedance ratio was reduced (P<0.05) in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) III and IV (compared to those with GOLD I and II) or a BODE index between 6 and 10 points (compared to those with BODE index between 1 and 5 points). Conclusion MF-BIA may be a useful tool for assessing body composition and nutritional status in COPD patients. In particular, the impedance ratio could give valuable information on cellular integrity and muscle quality.

  5. Evaluation of bioelectrical impedance analysis for identifying overweight individuals at increased cardiometabolic risk: a cross-sectional study.

    Directory of Open Access Journals (Sweden)

    Maxine J E Lamb

    Full Text Available OBJECTIVE: To investigate whether bioelectrical impedance analysis could be used to identify overweight individuals at increased cardiometabolic risk, defined as the presence of metabolic syndrome and/or diabetes. DESIGN AND METHODS: Cross-sectional study of a Scottish population including 1210 women and 788 men. The diagnostic performance of thresholds of percentage body fat measured by bioelectrical impedance analysis to identify people at increased cardiometabolic risk was assessed using receiver-operating characteristic curves. Odds ratios for increased cardiometabolic risk in body mass index categories associated with values above compared to below sex-specific percentage body fat thresholds with optimal diagnostic performance were calculated using multivariable logistic regression analyses. The validity of bioelectrical impedance analysis to measure percentage body fat in this population was tested by examining agreement between bioelectrical impedance analysis and dual-energy X-ray absorptiometry in a subgroup of individuals. RESULTS: Participants were aged 16-91 years and the optimal bioelectrical impedance analysis cut-points for percentage body fat for identifying people at increased cardiometabolic risk were 25.9% for men and 37.1% for women. Stratifying by these percentage body fat cut-points, the prevalence of increased cardiometabolic risk was 48% and 38% above the threshold and 24% and 19% below these thresholds for men and women, respectively. By comparison, stratifying by percentage body fat category had little impact on identifying increased cardiometabolic risk in normal weight and obese individuals. Fully adjusted odds ratios of being at increased cardiometabolic risk among overweight people with percentage body fat ≥ 25.9/37.1% compared with percentage body fat <25.9/37.1% as a reference were 1.93 (95% confidence interval: 1.20-3.10 for men and 1.79 (1.10-2.92 for women. CONCLUSION: Percentage body fat measured using

  6. The potential of classic and specific bioelectrical impedance vector analysis for the assessment of sarcopenia and sarcopenic obesity

    OpenAIRE

    Marini E; Buffa R; Saragat B; Coin A; Toffanello ED; Berton L; Manzato E; Sergi G

    2012-01-01

    Elisabetta Marini,1 Roberto Buffa,1 Bruno Saragat,1 Alessandra Coin,2 Elena Debora Toffanello,2 Linda Berton,2 Enzo Manzato,2 Giuseppe Sergi21Department of Environmental and Life Sciences, University of Cagliari, Italy; 2Department of Medicine-DIMED, Geriatrics Section, University of Padua, ItalyPurpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA) can be a suitable technique for the assessment of sarcopenia. We also investigate the potential ...

  7. The efficacy of Bioelectrical Impedance Analysis (BIA) in monitoring body composition changes during treatment of restrictive eating disorder patients

    OpenAIRE

    Saladino, Charles F

    2014-01-01

    Reviews Treating restrictive eating disorder patients is metabolically and psychologically complex. Determining body composition is an important diagnostic and treatment option for these patients, because it ascertains whether the acquisition of body mass during refeeding is metabolically appropriate - ideally an approximate 20/80% - 25/75% fat/lean body mass ratio. The purpose of this paper is to evaluate the efficacy of Bioelectrical Impedance Analysis (BIA) during the treatment period of p...

  8. Prediction of Fat-Free Mass Using Bioelectrical Impedance Analysis in Young Adults from Five Populations of African Origin

    OpenAIRE

    Luke, Amy; Bovet, Pascal; Forrester, Terrence E.; Lambert, Estelle V; Plange-Rhule, Jacob; Dugas, Lara R.; Durazo-Arvizu, Ramon A; Kroff, Jacolene; Richie, Whitney N.; Schoeller, Dale A

    2013-01-01

    Background/Objectives Bio-electrical impedance analysis (BIA) is used in population and clinical studies as a technique for estimating body composition. Because of significant underrepresentation in existing literature, we sought to develop and validate predictive equation(s) for BIA for studies in populations of African origin. Subjects/Methods Among five cohorts of the Modeling the Epidemiologic Transition Study (METS), height, weight, waist circumference and body composition, using isotope...

  9. Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets

    Directory of Open Access Journals (Sweden)

    Raquel D. Langer

    2016-03-01

    Full Text Available Background: Bioelectrical Impedance Analysis (BIA is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA as a reference method. Student’s t-test (for paired sample, linear regression analysis, and Bland–Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05 and large limits of agreement by Bland–Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.

  10. Estimation of fat-free mass in Asian neonates using bioelectrical impedance analysis.

    Science.gov (United States)

    Tint, Mya-Thway; Ward, Leigh C; Soh, Shu E; Aris, Izzuddin M; Chinnadurai, Amutha; Saw, Seang Mei; Gluckman, Peter D; Godfrey, Keith M; Chong, Yap-Seng; Kramer, Michael S; Yap, Fabian; Lingwood, Barbara; Lee, Yung Seng

    2016-03-28

    The aims of this study were to develop and validate a prediction equation of fat-free mass (FFM) based on bioelectrical impedance analysis (BIA) and anthropometry using air-displacement plethysmography (ADP) as a reference in Asian neonates and to test the applicability of the prediction equations in an independent Western cohort. A total of 173 neonates at birth and 140 at two weeks of age were included. Multiple linear regression analysis was performed to develop the prediction equations in a two-third randomly selected subset and validated on the remaining one-third subset at each time point and in an independent Queensland cohort. FFM measured by ADP was the dependent variable, and anthropometric measures, sex and impedance quotient (L2/R50) were independent variables in the model. Accuracy of prediction equations was assessed using intra-class correlation and Bland-Altman analyses. L2/R50 was the significant predictor of FFM at week two but not at birth. Compared with the model using weight, sex and length, including L2/R50 slightly improved the prediction with a bias of 0·01 kg with 2 sd limits of agreement (LOA) (0·18, -0·20). Prediction explained 88·9 % of variation but not beyond that of anthropometry. Applying these equations to the Queensland cohort provided similar performance at the appropriate age. However, when the Queensland equations were applied to our cohort, the bias increased slightly but with similar LOA. BIA appears to have limited use in predicting FFM in the first few weeks of life compared with simple anthropometry in Asian populations. There is a need for population- and age-appropriate FFM prediction equations. PMID:26856420

  11. Bioelectrical impedance vector analysis for evaluating zinc supplementation in prepubertal and healthy children

    Directory of Open Access Journals (Sweden)

    Márcia Marília Gomes Dantas

    2015-09-01

    Full Text Available Background: The prevalence of abnormal nutritional status has increased in children and adolescents. Nutritional assessment is important for monitoring the health and nutritional status. Bioelectrical impedance vector analysis (BIVA combines changes in tissue hydration and structure and body composition that can be assessed. Objectives: The objective of this study was to use BIVA to evaluate nutritional status in 60 prepubertal children, aged between 8 and 9 years, supplemented with zinc, to detect possible changes in body composition. Design: We performed a randomized, controlled, triple-blind study. The children were divided into the control group (CG; sorbitol 10%, n=29 or the experimental group (EG; 10 mg Zn/day, n=31, and the duration of the experiment was 3 months. Anthropometric assessments were performed for all of the children. Results: The body mass index-for-age increased after oral zinc supplementation in the EG (p=0.005. BIVA indicated that the CG demonstrated a tendency for dehydration and decreased soft tissue and the EG demonstrated a tendency for increased soft tissue, primarily the fat-free mass. After analyses of BIVA ellipses, we observed that this method could detect improvements in body composition in healthy children supplemented with zinc. Conclusions: These results suggest that BIVA could be an auxiliary method for studying a small population undergoing zinc intervention.

  12. Bioelectrical impedance analysis determination of water content and distribution in the horse.

    Science.gov (United States)

    Latman, Neal S; Keith, Natalie; Nicholson, Alan; Davis, Michael

    2011-06-01

    A horse's hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA values and simple biometric measurements were used to construct predictive equations for total body water, plasma, extracellular, and intra-cellular fluid volumes. These predictive equations were correlated with standard body fluid dilution reference methods. The result was an accuracy of ±0.64% for total body water, ±0.17% for plasma volume, ±1.91% for extra-cellular fluid, and ±0.57% for intra-cellular fluid compartments. Less than 5 min was required for all of the measurements and determinations. Therefore, it appears that an accurate measurement of body fluid distribution can be performed on horses using a fast, easy, non-invasive, inexpensive BIA method.

  13. Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

    Directory of Open Access Journals (Sweden)

    de Blasio F

    2016-09-01

    Full Text Available Francesca de Blasio,1 Francesco de Blasio,2,3 Giulia Miracco Berlingieri,2 Andrea Bianco,3,4 Marta La Greca,1 Frits M E Franssen,5 Luca Scalfi1 1Department of Public Health, Medical School, “Federico II” University of Naples, 2Respiratory Medicine and Pulmonary Rehabilitation Section, Clinic Center, Private Hospital, Naples, 3Department of Medicine and Health Sciences “V Tiberio”, University of Molise, Campobasso, 4Department of Cardio-Thoracic and Respiratory Sciences, Second University of Naples, Naples, Italy; 5Department of Research and Education, CIRO, Horn, the NetherlandsBackground: Multifrequency bioelectrical impedance analysis (MF-BIA is a technique that measures body impedance (Z at different frequencies (5, 10, 50, 100, and 250 kHz. Body composition may be estimated using empirical equations, which include BIA variables or, alternatively, raw BIA data may provide direct information on water distribution and muscle quality.Objectives: To compare raw MF-BIA data between COPD patients and controls and to study their relationship with respiratory and functional parameters in COPD patients.Methods: MF-BIA was performed (Human Im-Touch analyzer in 212 COPD patients and 115 age- and BMI-matched controls. Fat-free mass (FFM and fat mass were estimated from BIA data, and low- to high-frequency (5 kHz/250 kHz impedance ratio was calculated. Physical fitness, lung function and respiratory muscle strength were also assessed in COPD patients.Results: After adjusting for age, weight, and body mass index, FFM and the 5/250 impedance ratio were lower in COPD patients (P<0.001 and were negatively affected by disease severity. In both male and female patients, the 5/250 impedance ratio was significantly correlated mainly with age (r=−0.316 and r=−0.346, respectively. Patients with a 5/250 impedance ratio below median value had lower handgrip strength (P<0.001, 6-minute walk distance (P<0.005, respiratory muscle strength (P<0.005, forced

  14. Bioelectrical impedance modelling of gentamicin pharmacokinetic parameters.

    Science.gov (United States)

    Zarowitz, B J; Pilla, A M; Peterson, E L

    1989-10-01

    1. Bioelectrical impedance analysis was used to develop descriptive models of gentamicin pharmacokinetic parameters in 30 adult in-patients receiving therapy with gentamicin. 2. Serial blood samples obtained from each subject at steady state were analyzed and used to derive gentamicin pharmacokinetic parameters. 3. Multiple regression equations were developed for clearance, elimination rate constant and volume of distribution at steady state and were all statistically significant at P less than 0.05. 4. Clinical validation of this innovative technique is warranted before clinical use is recommended.

  15. Bioelectrical impedance analysis in clinical practice: implications for hepatitis C therapy BIA and hepatitis C

    Directory of Open Access Journals (Sweden)

    Kahraman Alisan

    2010-08-01

    Full Text Available Abstract Background Body composition analysis using phase angle (PA, determined by bioelectrical impedance analysis (BIA, reflects tissue electrical properties and has prognostic value in liver cirrhosis. Objective of this prospective study was to investigate clinical use and prognostic value of BIA-derived phase angle and alterations in body composition for hepatitis C infection (HCV following antiviral therapy. Methods 37 consecutive patients with HCV infection were enrolled, BIA was performed, and PA was calculated from each pair of measurements. 22 HCV genotype 3 patients treated for 24 weeks and 15 genotype 1 patients treated for 48 weeks, were examined before and after antiviral treatment and compared to 10 untreated HCV patients at 0, 24, and 48 weeks. Basic laboratory data were correlated to body composition alterations. Results Significant reduction in body fat (BF: 24.2 ± 6.7 kg vs. 19.9 ± 6.6 kg, genotype1; 15.4 ± 10.9 kg vs. 13.2 ± 12.1 kg, genotype 3 and body cell mass (BCM: 27.3 ± 6.8 kg vs. 24.3 ± 7.2 kg, genotype1; 27.7 ± 8.8 kg vs. 24.6 ± 7.6 kg, genotype 3 was found following treatment. PA in genotype 3 patients was significantly lowered after antiviral treatment compared to initial measurements (5.9 ± 0.7° vs. 5.4 ± 0.8°. Total body water (TBW was significantly decreased in treated patients with genotype 1 (41.4 ± 7.9 l vs. 40.8 ± 9.5 l. PA reduction was accompanied by flu-like syndromes, whereas TBW decline was more frequently associated with fatigue and cephalgia. Discussion BIA offers a sophisticated analysis of body composition including BF, BCM, and TBW for HCV patients following antiviral regimens. PA reduction was associated with increased adverse effects of the antiviral therapy allowing a more dynamic therapy application.

  16. Bioimpedance Vector Pattern in Taiwanese and Polish College Students Detected by Bioelectric Impedance Vector Analysis: Preliminary Observations

    Directory of Open Access Journals (Sweden)

    Teresa Malecka-Massalska

    2012-01-01

    Full Text Available Background and Objectives. The study was conducted to evaluate soft tissue hydration and mass through pattern analysis of vector plots as height, normalized resistance, and reactance measurements by bioelectric impedance vector analysis in Taiwanese and Polish college students. Methods. Whole-body measurements were made with ImpediMed bioimpedance analysis SFB7 BioImp v1.55 (Pinkenba Qld 4008, Australia in 16 Taiwanese and Polish men and 16 Taiwanese and Polish women. Results. Mean vectors of Taiwanese men and women groups versus the Polish men and women groups were characterized by almost the same normalized resistance component with reactance component (separate 95% confidence limits, <0.05 indicating that there were no differences of soft tissue hydration and mass. Interpretation and Conclusion. The evaluation of soft tissue hydration and mass through pattern analysis of vector plots as height, normalized resistance, and reactance measurements by bioelectric impedance vector analysis in Taiwanese and Polish college students did not differ between these two diverse ethnic groups. Further observational research investigating these properties in larger groups would be welcomed to elucidate and/or confirm these findings.

  17. The potential of classic and specific bioelectrical impedance vector analysis for the assessment of sarcopenia and sarcopenic obesity

    Directory of Open Access Journals (Sweden)

    Marini E

    2012-12-01

    Full Text Available Elisabetta Marini,1 Roberto Buffa,1 Bruno Saragat,1 Alessandra Coin,2 Elena Debora Toffanello,2 Linda Berton,2 Enzo Manzato,2 Giuseppe Sergi21Department of Environmental and Life Sciences, University of Cagliari, Italy; 2Department of Medicine-DIMED, Geriatrics Section, University of Padua, ItalyPurpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA can be a suitable technique for the assessment of sarcopenia. We also investigate the potential use of specific BIVA as an indicator of sarcopenic obesity.Subjects and methods: The sample comprised 207 free-living elderly individuals of both sexes, aged 65 to 93 years. Anthropometric and bioelectrical measurements were taken according to standard criteria. The “classic” and “specific” BIVA procedures, which respectively correct bioelectrical values for body height and body geometry, were used. Dual energy X-ray absorptiometry (DXA was used as the reference method for identifying sarcopenic and obese sarcopenic individuals. Bioelectrical and DXA values were compared using Student’s t-test and Hotelling’s T2 test, as well as Pearson’s correlation coefficient.Results: According to classic BIVA, sarcopenic individuals of both sexes showed higher values of resistance/height (R/H; p < 0.01 and impedance/height (Z/H; p < 0.01, and a lower phase angle (p < 0.01. Similarly, specific BIVA showed significant differences between sarcopenic and nonsarcopenic individuals (men: T2 = 15.7, p < 0.01; women: T2 = 10.7, p < 0.01, with the sarcopenic groups showing a lower specific reactance and phase angle. Phase angle was positively correlated with the skeletal muscle mass index (men: r = 0.52, p < 0.01; women: r = 0.31, p < 0.01. Specific BIVA also recognized bioelectrical differences between sarcopenic and sarcopenic obese men (T2 = 13.4, p < 0.01, mainly due to the higher values of specific R in sarcopenic obese individuals.Conclusion: BIVA detected

  18. Validity of estimating limb muscle volume by bioelectrical impedance.

    Science.gov (United States)

    Miyatani, M; Kanehisa, H; Masuo, Y; Ito, M; Fukunaga, T

    2001-07-01

    The present study aimed to investigate the validity of estimating muscle volume by bioelectrical impedance analysis. Bioelectrical impedance and series cross-sectional images of the forearm, upper arm, lower leg, and thigh on the right side were determined in 22 healthy young adult men using a specially designed bioelectrical impedance acquisition system and magnetic resonance imaging (MRI) method, respectively. The impedance index (L(2)/Z) for every segment, calculated as the ratio of segment length squared to the impedance, was significantly correlated to the muscle volume measured by MRI, with r = 0.902-0.976 (P estimation was 38.4 cm(3) for the forearm, 40.9 cm(3) for the upper arm, 107.2 cm(3) for the lower leg, and 362.3 cm(3) for the thigh. Moreover, isometric torque developed in elbow flexion or extension and knee flexion or extension was significantly correlated to the L(2)/Z values of the upper arm and thigh, respectively, with correlation coefficients of 0.770-0.937 (P knee flexors or extensors. Thus the present study indicates that bioelectrical impedance analysis may be useful to predict the muscle volume and to investigate possible relations between muscle size and strength capability in a limited segment of the upper and lower limbs.

  19. Bioelectrical impedance analysis and anthropometry for the determination of body composition in rats: effects of high-fat and high-sucrose diets

    Directory of Open Access Journals (Sweden)

    Larissa Rodrigues Neto Angéloco

    2012-06-01

    Full Text Available OBJECTIVE: The aim of the present study was to determine the impedance of Wistar rats treated with high-fat and high-sucrose diets and correlate their biochemical and anthropometric parameters with chemical analysis of the carcass. METHODS: Twenty-four male Wistar rats were fed a standard (AIN-93, high-fat (50% fat or high-sucrose (59% of sucrose diet for 4 weeks. Abdominal and thoracic circumference and body length were measured. Bioelectrical impedance analysis was used to determine resistance and reactance. Final body composition was determined by chemical analysis. RESULTS: Higher fat intake led to a high percentage of liver fat and cholesterol and low total body water in the High-Fat group, but these changes in the biochemical profile were not reflected by the anthropometric measurements or bioelectrical impedance analysis variables. Anthropometric and bioelectrical impedance analysis changes were not observed in the High-Sucrose group. However, a positive association was found between body fat and three anthropometric variables: body mass index, Lee index and abdominal circumference. CONCLUSION: Bioelectrical impedance analysis did not prove to be sensitive for detecting changes in body composition, but body mass index, Lee index and abdominal circumference can be used for estimating the body composition of rats.

  20. The Effect of an Acute After-School Exercise Bout on Percentage of Body Fat Using Leg-to-Leg Bioelectrical Impedance Analysis in Children

    Science.gov (United States)

    Andreacci, Joseph L.; Dixon, Curt B.; Rompolski, Krista; VanGorden, Kelly M.

    2008-01-01

    Bioelectrical impedance analysis (BIA) is a fast, easy to administer, and relatively inexpensive method of evaluating body composition. Due to the ease of operation, interest in using BIA to estimate percentage of body fat (%BF) has grown, especially in settings where body composition assessments are often performed without the benefit of…

  1. Inter-sport variability of muscle volume distribution identified by segmental bioelectrical impedance analysis in four ball sports

    Directory of Open Access Journals (Sweden)

    Yamada Y

    2013-04-01

    Full Text Available Yosuke Yamada,1,2 Yoshihisa Masuo,3 Eitaro Nakamura,4 Shingo Oda5 1Laboratory of Sports and Health Science, Kyoto Prefectural University of Medicine, Kyoto, Japan; 2Japan Society for the Promotion of Science, Tokyo, Japan; 3Waseda University Research Institute for Elderly Health, Saitama, Japan; 4Department of Sport Science, Kyoto Iken College of Medicine and Health, Kyoto, Japan; 5Faculty of Health and Well-being, Kansai University, Osaka, Japan Abstract: The aim of this study was to evaluate and quantify differences in muscle distribution in athletes of various ball sports using segmental bioelectrical impedance analysis (SBIA. Participants were 115 male collegiate athletes from four ball sports (baseball, soccer, tennis, and lacrosse. Percent body fat (%BF and lean body mass were measured, and SBIA was used to measure segmental muscle volume (MV in bilateral upper arms, forearms, thighs, and lower legs. We calculated the MV ratios of dominant to nondominant, proximal to distal, and upper to lower limbs. The measurements consisted of a total of 31 variables. Cluster and factor analyses were applied to identify redundant variables. The muscle distribution was significantly different among groups, but the %BF was not. The classification procedures of the discriminant analysis could correctly distinguish 84.3% of the athletes. These results suggest that collegiate ball game athletes have adapted their physique to their sport movements very well, and the SBIA, which is an affordable, noninvasive, easy-to-operate, and fast alternative method in the field, can distinguish ball game athletes according to their specific muscle distribution within a 5-minute measurement. The SBIA could be a useful, affordable, and fast tool for identifying talents for specific sports. Keywords: discriminant analysis, cluster and factor analysis, segmental bioelectrical impedance analysis, baseball, lacrosse

  2. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    Science.gov (United States)

    Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C

    2016-06-01

    Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs.

  3. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    Science.gov (United States)

    Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C

    2016-06-01

    Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs. PMID:27256027

  4. Bioelectric impedance phase angle in breast carcinoma

    Directory of Open Access Journals (Sweden)

    Ruchi Tyagi

    2014-01-01

    Full Text Available Context: Worldwide breast cancer is the most frequently diagnosed life threatening cancer and the leading cause of death in women. Bioelectric impedance analysis (BIA affords an emerging opportunity to assess prognosis because of its ability to non invasively assess cell and plasma membrane structure and function by means of phase angle. Aims: To compare the phase angle between patients of breast cancer and their matched control with the help of BIA. Settings and Design: After taking clearance from ethical committee, a total of 34 female cases of histologically proven infiltrating ductal breast carcinoma were included from the surgery IPD, department of surgery. Equal numbers of the matched controls were recruited from the friends and relatives of cases. Materials and Methods: Bio Electrical Impedance Analyzer (BIA BODY STAT QUAD SCAN 4000 was used to measure resistance (R and reactance (Xc by recording a voltage drop in applied current. Phase angle is the ratio of reactance to resistance and is a measure of cell vitality. Statistical analysis used: Unpaired "t" test was applied. Results: In control group, the phase angle showed a mean of 5.479 whereas in test group, it showed a mean value of 4.726. The P value showed a significant difference (P < 0.0001. The smaller the phase angle values were higher was the tumor, nodes, metastases (TNM staging. The phase angles differed significantly from the healthy age matched control values. Conclusions: This study demonstrated that phase angle is a strong predictor of severity of breast cancer and differed significantly between the two groups.

  5. Experimental verification of depolarization effects in bioelectrical impedance measurement.

    Science.gov (United States)

    Chen, Xiaoyan; Lv, Xinqiang; Du, Meng

    2014-01-01

    The electrode polarization effects on bioelectrical impedance measurement at low-frequency cannot be ignored. In this paper, the bioelectrical data of mice livers are measured to specify the polarization effects on the bio-impedance measurement data. We firstly introduce the measurement system and methodology. Using the depolarization method, the corrected results are obtained. Besides, the specific effects of electrode polarization on bio-impedance measurement results are investigated using comparative analysis of the previous and posterior correction results from dielectric spectroscopy, Cole-Cole plot, conductivity and spectroscopy of dissipation tangent. Experimental results show that electrode polarization has a significant influence on the characteristic parameters of mouse liver tissues. To be specific, we see a low-frequency limit resistance R0 increase by 19.29%, a reactance peak XP increase by 8.50%, a low-frequency limit conductivity Kl decrease by 17.65% and a dissipation peak tangent decrease by 160%.

  6. Design and implementation of an impedance analyzer based on Arduino Uno : A pilot study of bioelectrical impedance analysis

    OpenAIRE

    Wang, Jing

    2015-01-01

    Electrical bioimpedance measurement is widely used today for monitoring body condition. The applications include and go beyond, body composition assessment, nutritional status evaluation, and cancer detection. The modalities for interpreting the impedance information have also developed quickly over the recent decades from single frequency bioimpedance analysis to spectrum and to images. Bioimpedance is measured by computing the relationship between voltage and current. In a current based bio...

  7. Impact of hyperhydration on the mortality risk in critically ill patients admitted in intensive care units: comparison between bioelectrical impedance vector analysis and cumulative fluid balance recording

    OpenAIRE

    Samoni, Sara; Vigo, Valentina; Reséndiz, Luis Ignacio Bonilla; Villa, Gianluca; De Rosa, Silvia; Nalesso, Federico; Ferrari, Fiorenza; Meola, Mario; Brendolan, Alessandra; Malacarne, Paolo; Forfori, Francesco; Bonato, Raffaele; Donadio, Carlo; Ronco, Claudio

    2016-01-01

    Background Studies have demonstrated a positive correlation between fluid overload (FO) and adverse outcomes in critically ill patients. The present study aims at defining the impact of hyperhydration on the Intensive Care Unit (ICU) mortality risk, comparing Bioelectrical Impedance Vector Analysis (BIVA) assessment with cumulative fluid balance (CFB) recording. Methods We performed a prospective, dual-centre, clinician-blinded, observational study of consecutive patients admitted to ICU with...

  8. Fat-free mass prediction equations for bioelectric impedance analysis compared to dual energy X-ray absorptiometry in obese adolescents: a validation study

    OpenAIRE

    Hofsteenge, Geesje H.; Chinapaw, Mai JM; Weijs, Peter JM

    2015-01-01

    Background In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11–18 years) compared to FFM measured by dual-energy x-ray absorptiometry (FFM-DXA) and a new population specific FFM-BIA equation is developed. Methods After an overnight fast, the subjects attended the outpatient clinic. Af...

  9. The investigation of the some body parameters of obese and (obese+diabetes) patients with using bioelectrical impedance analysis techniques

    Science.gov (United States)

    Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep

    2016-04-01

    Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount pbody mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result of a sedentary lifestyle.

  10. [Effects of different electrodes on bioelectrical impedance values].

    Science.gov (United States)

    Nakadomo, F; Tanaka, K; Yokoyama, T; Maeda, K

    1990-01-01

    Effects of different electrodes on bioelectrical impedance values measured by the Selco bioelectrical impedance plethysmograph (SIF-881, Japan) were investigated using 8 adult females (age: 35.3 +/- 7.6 yr, Ht: 156.9 +/- 3.8 cm, Wt: 57.1 +/- 9.9 kg, and hydrodensitometrically determined body fat: 29.4 +/- 6.0%). The Lectec MP3000 electrode (Liberty Carton, USA) and the Bipolar electrode (Sanwa, Japan) produced significantly higher impedance values when compared to the Disposable electrode (Adovance, Japan) and the ECG electrode (Nihon Kohden, Japan). The coefficient of variation was significantly lower for the Disposable electrode (0.8%) and the ECG electrode (0.2%) than that for the Lectec MP3000 electrode (2.3%) and the Bipolar electrode (4.9%). In conclusion, the ECG electrode provides higher bioelectrical impedance values with the highest reproducibility in the assessment of human body composition by the bioelectrical impedance plethysmography.

  11. Comparison of body fat in Brazilian adult females by bioelectrical impedance analysis

    Science.gov (United States)

    Altamir, Vaz; Frère, Slaets Annie France; Ramírez Leonardo, López

    2012-12-01

    Body-fat is essential for human body, provided that its amount is at healthy levels. If in-excess body-fat is deleterious, its lack is otherwise also harmful. Estimated percent body-fat performed with commercially available devices measuring bioimpedance have many advantages, such as easy measurement and low cost. However, these measurements are based on standard models and equations that are not disclosed by manufacturers, and this leads to questioning the validity of these estimates for Brazilian females. The aim of this study was to compare electrical tetrapolar and octapolar impedance results obtained with commercially available equipment: Maltron BF-906 and OMRON 510-W. Data analysis involved descriptive and inferential statistics. Devices used in this study to estimate body fat quantity have not shown any significant differences in results; this is a major issue when selecting equipment based on three factors: study focus, available financial resources, and target population. Results obtained from the two devices have not shown any significant differences, which lead to the conclusion that either device may be reliably used.

  12. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population

    Science.gov (United States)

    Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B.; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

    2016-01-01

    Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065

  13. The investigation of the some body parameters of obese and (obese+diabetes) patients with using bioelectrical impedance analysis techniques

    Science.gov (United States)

    Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep

    2016-04-01

    Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount p<0.00 between (diabetes+obese) and obese groups. Besides, when these patient groups and control group were analyzed, there were significant difference between most parameters. In terms of education level among the illiterate and university graduates; fat mass kg, fat percentage, internal lubrication, body mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result

  14. Preliminary bioelectrical impedance analysis (BIA) equation for body composition assessment in young females from Colombia

    Science.gov (United States)

    Caicedo-Eraso, J. C.; González-Correa, C. H.; González-Correa, C. A.

    2013-04-01

    A previous study showed that reported BIA equations for body composition are not suitable for Colombian population. The purpose of this study was to develop and validate a preliminary BIA equation for body composition assessment in young females from Colombia, using hydrodensitometry as reference method. A sample of 30 young females was evaluated. Inclusion and exclusion criteria were defined to minimize the variability of BIA. Height, weight, BIA, residual lung volume (RV) and underwater weight (UWW) were measured. A preliminary BIA equation was developed (r2 = 0.72, SEE = 2.48 kg) by stepwise multiple regression with fat-free mass (FFM) as dependent variable and weight, height and impedance measurements as independent variables. The quality of regression was evaluated and a cross-validation against 50% of sample confirmed that results obtained with the preliminary BIA equation is interchangeable with results obtained with hydrodensitometry (r2 = 0.84, SEE = 2.62 kg). The preliminary BIA equation can be used for body composition assessment in young females from Colombia until a definitive equation is developed. The next step will be increasing the sample, including a second reference method, as deuterium oxide dilution (D2O), and using multi-frequency BIA (MF-BIA). It would also be desirable to develop equations for males and other ethnic groups in Colombia.

  15. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2012-01-01

    Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.

  16. Malnutrition in remission of childhood cancers as assessed by bioelectric impedance analysis

    Directory of Open Access Journals (Sweden)

    M. V. Konovalova

    2014-07-01

    Full Text Available The results of our cross-sectional bioimpedance study of children aged 7–17 years cured of cancer during follow-up (patients’ group, n = 552, remission time range 0–15 years and of age-matched healthy controls (n = 1,500 show significant intergroup differences in body height and body composition parameters. The most pronounced alterations in the patients’ group were observed in standardized values of phase angle reflecting a sharp decrease in the percentage of metabolically active body cell mass in fat-free mass. Malnutrition, judged from the prevalence of obesity and low phase angle, was observed in 52.7 % of our patients reaching a maximum of 76.8 % in a subgroup of children with CNS tumors. In view of known association that exists between malnutrition and reduced tolerance to chemotherapy, increased susceptibility to infections and adverse outcomes rate, we recommend using bioimpedance analysis in remission of childhood cancers in order to monitoring and timely correction of nutritional state as well as for prevention of delayed cardiovascular risks.

  17. Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.

    Science.gov (United States)

    Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J

    2016-08-01

    Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment.

  18. Smart Multi-Frequency Bioelectrical Impedance Spectrometer for BIA and BIVA Applications.

    Science.gov (United States)

    Harder, Rene; Diedrich, Andre; Whitfield, Jonathan S; Buchowski, Macie S; Pietsch, John B; Baudenbacher, Franz J

    2016-08-01

    Bioelectrical impedance analysis (BIA) is a noninvasive and commonly used method for the assessment of body composition including body water. We designed a small, portable and wireless multi-frequency impedance spectrometer based on the 12 bit impedance network analyzer AD5933 and a precision wide-band constant current source for tetrapolar whole body impedance measurements. The impedance spectrometer communicates via Bluetooth with mobile devices (smart phone or tablet computer) that provide user interface for patient management and data visualization. The export of patient measurement results into a clinical research database facilitates the aggregation of bioelectrical impedance analysis and biolectrical impedance vector analysis (BIVA) data across multiple subjects and/or studies. The performance of the spectrometer was evaluated using a passive tissue equivalent circuit model as well as a comparison of body composition changes assessed with bioelectrical impedance and dual-energy X-ray absorptiometry (DXA) in healthy volunteers. Our results show an absolute error of 1% for resistance and 5% for reactance measurements in the frequency range of 3 kHz to 150 kHz. A linear regression of BIA and DXA fat mass estimations showed a strong correlation (r(2)=0.985) between measures with a maximum absolute error of 6.5%. The simplicity of BIA measurements, a cost effective design and the simple visual representation of impedance data enables patients to compare and determine body composition during the time course of a specific treatment plan in a clinical or home environment. PMID:26863670

  19. Effect of the ethinylestradiol/norelgestromin contraceptive patch on body composition. Results of bioelectrical impedance analysis in a population of Italian women

    Directory of Open Access Journals (Sweden)

    Bruni Vincenzina

    2008-08-01

    Full Text Available Abstract Background As weight gain is one of the most frequently cited reasons for not using and for discontinuing hormonal contraceptives, in an open-label, single-arm, multicentre clinical study we evaluated the effect of the ethinylestradiol/norelgestromin contraceptive patch (EVRA, Janssen-Cilag International, Belgium on body composition using bioelectrical impedance analysis (BIA. Methods Body weight and impedance vector components (resistance (R and reactance (Xc, at 50 kHz frequency, Akern-RJL Systems analyzer were recorded before entry, after 1, 3 and 6 months in 182 Italian healthy women aged 29 yr (18 to 45, and with BMI 21.8 kg/m2 (16 to 31. Total body water (TBW was estimated with a BIA regression equation. Vector BIA was performed with the RXc mean graph method and the Hotelling's T2 test for paired and unpaired data. Results After 6 months body weight increased by 0.64 kg (1.1% and TBW increased by 0.51 L (1.7%. The pattern of impedance vector displacement indicated a small increase in soft tissue hydration (interstitial gel fluid. Body composition changes did not significantly differ among groups of previous contraceptive methods. Arterial blood pressure did not significantly change over time. Conclusion After 6 months of treatment with the ethinylestradiol/norelgestromin contraceptive patch we found a minimal, clinically not relevant, increase in body weight less than 1 kg that could be attributed to an adaptive interstitial gel hydration. This fluctuation is physiological as confirmed by the lack of any effect on blood pressure. This could be useful in increasing women's choice, acceptability and compliance of the ethinylestradiol/norelgestromin contraceptive patch.

  20. Prediction of fat-free mass and percentage of body fat in neonates using bioelectrical impedance analysis and anthropometric measures: validation against the PEA POD.

    Science.gov (United States)

    Lingwood, Barbara E; Storm van Leeuwen, Anne-Martine; Carberry, Angela E; Fitzgerald, Erin C; Callaway, Leonie K; Colditz, Paul B; Ward, Leigh C

    2012-05-01

    Accurate assessment of neonatal body composition is essential to studies investigating neonatal nutrition or developmental origins of obesity. Bioelectrical impedance analysis or bioimpedance analysis is inexpensive, non-invasive and portable, and is widely used in adults for the assessment of body composition. There are currently no prediction algorithms using bioimpedance analysis in neonates that have been directly validated against measurements of fat-free mass (FFM). The aim of the study was to evaluate the use of bioimpedance analysis for the estimation of FFM and percentage of body fat over the first 4 months of life in healthy infants born at term, and to compare these with estimations based on anthropometric measurements (weight and length) and with skinfolds. The present study was an observational study in seventy-seven infants. Body fat content of infants was assessed at birth, 6 weeks, 3 and 4·5 months of age by air displacement plethysmography, using the PEA POD body composition system. Bioimpedance analysis was performed at the same time and the data were used to develop and test prediction equations for FFM. The combination of weight+sex+length predicted FFM, with a bias of < 100 g and limits of agreement of 6-13 %. Before 3 months of age, bioimpedance analysis did not improve the prediction of FFM or body fat. At 3 and 4·5 months, the inclusion of impedance in prediction algorithms resulted in small improvements in prediction of FFM, reducing the bias to < 50 g and limits of agreement to < 9 %. Skinfold measurements performed poorly at all ages.

  1. Is bioelectrical impedance accurate for use in large epidemiological studies?

    Directory of Open Access Journals (Sweden)

    Merchant Anwar T

    2008-09-01

    Full Text Available Abstract Percentage of body fat is strongly associated with the risk of several chronic diseases but its accurate measurement is difficult. Bioelectrical impedance analysis (BIA is a relatively simple, quick and non-invasive technique, to measure body composition. It measures body fat accurately in controlled clinical conditions but its performance in the field is inconsistent. In large epidemiologic studies simpler surrogate techniques such as body mass index (BMI, waist circumference, and waist-hip ratio are frequently used instead of BIA to measure body fatness. We reviewed the rationale, theory, and technique of recently developed systems such as foot (or hand-to-foot BIA measurement, and the elements that could influence its results in large epidemiologic studies. BIA results are influenced by factors such as the environment, ethnicity, phase of menstrual cycle, and underlying medical conditions. We concluded that BIA measurements validated for specific ethnic groups, populations and conditions can accurately measure body fat in those populations, but not others and suggest that for large epdiemiological studies with diverse populations BIA may not be the appropriate choice for body composition measurement unless specific calibration equations are developed for different groups participating in the study.

  2. Validity of Bioelectrical Impedance Measurement in Predicting Fat-Free Mass of Chinese Children and Adolescents

    OpenAIRE

    Wang, Lin; Hui, Stanley Sai-chuen; Wong, Stephen Heung-sang

    2014-01-01

    Background The current study aimed to examine the validity of various published bioelectrical impedance analysis (BIA) equations in estimating FFM among Chinese children and adolescents and to develop BIA equations for the estimation of fat-free mass (FFM) appropriate for Chinese children and adolescents. Material/Methods A total of 255 healthy Chinese children and adolescents aged 9 to 19 years old (127 males and 128 females) from Tianjin, China, participated in the BIA measurement at 50 kHz...

  3. Segmental Body Composition Assessment for Obese Japanese Adults by Single-Frequency Bioelectrical Impedance Analysis with 8-point Contact Electrodes

    OpenAIRE

    Sato, Susumu; Demura, Shinichi; Kitabayashi, Tamotsu; Noguchi, Takanori

    2007-01-01

    This study aimed to determine the accuracy of segmental body composition variables estimated by singlefrequency BIA with 8-point contact electrodes (SF-BIA8), compared with dual-energy X-ray absorptiometry (DXA). Subjects were 72 obese Japanese adults (43 males and 29 females) aged 30 to 66 years. Segmental body composition variables (fat free mass : FFM, fat mass : FM, and percent fat mass : %FAT) were measured by these techniques. The correlations between impedance values and FFM measured b...

  4. Total body water and fat-free mass: evaluation of equations based on bioelectrical impedance analysis in infants and young children in India.

    Science.gov (United States)

    Sen, Bandana; Mahalanabis, Dilip; Kurpad, Anura V; Shaikh, Saijuddin; Bose, Kaushik

    2010-07-01

    The association of early postnatal growth with diseases in adults such as hypertension, type 2 diabetes and CHD has generated interest in studying postnatal growth. Bioelectrical impedance analysis (BIA) is a useful measure to estimate total body water (TBW) and fat-free mass (FFM). We evaluated three published equations (Fjeld et al. (Pediatr Res (1990) 27, 98-102), Bocage (MSc Thesis (1988) University of West Indies) and Kushner et al. (Am J Clin Nutr (1992) 56, 835-839) to measure TBW and derived FFM based on BIA, using 2H2O dilution as a reference method for suitability in infants in India. In a cross-sectional study in seventy-eight apparently healthy infants aged 6-24 months from the urban poor attending an immunisation clinic at a hospital in Kolkata, we measured their length to the nearest 0.1 cm, weight to the nearest 10 g, resistance at 50 kHz using BIA and TBW using 2H2O dilution. TBW was derived using three published BIA-based equations and compared with TBW using 2H2O dilution. Based on the BIA equations of Fjeld et al., Bocage and Kushner et al., the mean TBW values were 2.46 % (P < 0.001), 4.62 % (P < 0.001) and 9.50 % (P < 0.001) lower than the reference 2H2O method, respectively. All three published BIA-based equations consistently underestimated the TBW and FFM and appeared inadequate for studying infants in India. The equation described by Fjeld et al. gave the smallest deviation from the reference method and may be used for field studies. New equations based on population-specific data are desirable for a more precise measure of TBW. PMID:20188001

  5. Evaluation of the BOD POD and leg-to-leg bioelectrical impedance analysis for estimating percent body fat in National Collegiate Athletic Association Division III collegiate wrestlers.

    Science.gov (United States)

    Dixon, Curt B; Deitrick, Ronald W; Pierce, Joseph R; Cutrufello, Paul T; Drapeau, Linda L

    2005-02-01

    The purpose of this study was to compare percent body fat (%BF) estimated by air displacement plethysmography (ADP) and leg-to-leg bioelectrical impedance analysis (LBIA) with hydrostatic weighing (HW) in a group (n = 25) of NCAA Division III collegiate wrestlers. Body composition was assessed during the preseason wrestling weight certification program (WCP) using the NCAA approved methods (HW, 3-site skinfold [SF], and ADP) and LBIA, which is currently an unaccepted method of assessment. A urine specific gravity less than 1.020, measured by refractometry, was required before all testing. Each subject had all of the assessments performed on the same day. LBIA measurements (Athletic mode) were determined using a Tanita body fat analyzer (model TBF-300A). Hydrostatic weighing, corrected for residual lung volume, was used as the criterion measurement. The %BF data (mean +/- SD) were LBIA (12.3 +/- 4.6), ADP (13.8 +/- 6.3), SF (14.2 +/- 5.3), and HW (14.5 +/- 6.0). %BF estimated by LBIA was significantly (p < 0.01) smaller than HW and SF. There were no significant differences in body density or %BF estimated by ADP, SF, and HW. All methods showed significant correlations (r = 0.80-0.96; p < 0.01) with HW. The standard errors of estimate (SEE) for %BF were 1.68, 1.87, and 3.60%; pure errors (PE) were 1.88, 1.94, and 4.16% (ADP, SF, and LBIA, respectively). Bland-Atman plots for %BF demonstrated no systematic bias for ADP, SF, and LBIA when compared with HW. These preliminary findings support the use of ADP and SF for estimating %BF during the NCAA WCP in Division III wrestlers. LBIA, which consistently underestimated %BF, is not supported by these data as a valid assessment method for this athletic group.

  6. Calibration of bioelectrical impedance analysis for body composition assessment in Ethiopian infants using air-displacement plethysmography

    DEFF Research Database (Denmark)

    Christensen, Rasmus Wibæk; Kæstel, Pernille; Skov, R.;

    2015-01-01

    , age and an impedance index (L(2)/Z50) were predictors. Prediction equations were developed using stepwise multiple linear regression and the accuracy was evaluated with a 10-fold cross-validation approach. RESULTS: A linear regression model based on body weight, age and sex predicted FFM, estimated...... model fit for predicting FFM compared with a model already comprising weight, sex and age. CONCLUSIONS: The derived equations predicted FFM with acceptable accuracy and may be used in future field surveys, epidemiological studies and clinical trials conducted in similar sub-Saharan African population...... groups aged 0-6 months.European Journal of Clinical Nutrition advance online publication, 1 April 2015; doi:10.1038/ejcn.2015.51....

  7. Application of bioelectrical impedance vector analysis (BIVA in dogs: a preliminary study on gender-related differences

    Directory of Open Access Journals (Sweden)

    Rebecca Ricci

    2010-01-01

    Full Text Available In this preliminary study, BIVA has been performed on 17 healthy Italian Hound dogs, 10 males (M and 7 females (F, in order to verify if gender-related differences can be detected. Only in F higher reactance (Xc values (F: 46.4 vs M: 37.7, P<0.05 and a significant negative correlation (-0.80, P<0.05 between BCS and resistance (R values were detected. 50%, 75% and 95% tolerance ellipses were calculated both in M and F using average Xc and R values standardized for withers height. Probably due to the low number of subjects used in the present study, the variability of the individual vector distribution (F: 79.6 vs M: 53.0Ohm/m, as well as the mean impedance vector lengtht (F: 548.2 vs M: 498.9Ohm/m, were similar in F and M. The gender-related difference in phase angle values was not significant (F: 0.168 vs M: 0.157, P=ns. In conclusion, the use of BIVA in dogs indicated differences between males and females which should be confirmed by a larger number of subjects.

  8. Comparison of Bioelectrical Impedance and Skinfolds with Hydrodensitometry in the Assessment of Body Composition in Healthy Young Adults

    Science.gov (United States)

    Rutherford, W. J.; Diemer, Gary A.; Scott, Eric D.

    2011-01-01

    Bioelectrical impedance analysis (BIA) is a widely used method for estimating body composition, yet issues concerning its validity persist in the literature. The purpose of this study was to validate percentage of body fat (BF) values estimated from BIA and skinfold (SF) with those obtained from hydrodensitometry (HD). Percent BF values measured…

  9. Relationship of percent body fat (estimated by bioelectrical impedance analysis with blood pressure among young adult females of Amritsar (Punjab

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    Bindiya Rana

    2012-10-01

    Full Text Available The present cross-sectional study was carried out to find the association of percent body fat (PBF with blood pressure (BP variables among apparently healthy young females studying in Guru Nanak Dev University, Amritsar. A total of 150 females ranging in age from 20-25 years were personally interviewed. Height and weight of each subject was taken using standard methodology. Their body composition parameters were taken by using body fat analyzer. Subjects were categorized as obese and non-obese according to PBF, in which those having >30% body fat was considered as obese. BP of each subject was measured by using the standard methodology. The prevalence of hypertension was calculated according to JNC VII criteria. In the pooled data, the percentage prevalence of obesity according to PBF was 36%. The percentage prevalence of pre-hypertension and hypertension in the pooled sample was 54% and 12%, respectively. However, it was observed that prevalence of hypertension was slightly more among obese females (7.3% as compared to non-obese (4.7% but the prevalence of pre-hypertension was significantly (p<0.05 more in non-obese females (39.3% as compared to obese females (14.7%. The underline cause of this high prevalence of pre-hypertension in non-obese subjects was not known. It is clear from the correlation analysis that no association was observed between SBP and MAP with PBF in obese and non-obese subjects while DBP is positively and significantly (p<0.05 correlated with weight, fat mass and fat free mass in non-obese subjects only. Thus it is concluded from this study that PBF measured by BIA was not likely to be a good predictor of high BP. Therefore, further large prospective studies on the association of hypertension and whole body fat and abdominal fat should be carried out to confirm the role of fat on BP.

  10. Body fat measurement by bioelectrical impedance and air displacement plethysmography: a cross-validation study to design bioelectrical impedance equations in Mexican adults

    Directory of Open Access Journals (Sweden)

    Valencia Mauro E

    2007-08-01

    Full Text Available Abstract Background The study of body composition in specific populations by techniques such as bio-impedance analysis (BIA requires validation based on standard reference methods. The aim of this study was to develop and cross-validate a predictive equation for bioelectrical impedance using air displacement plethysmography (ADP as standard method to measure body composition in Mexican adult men and women. Methods This study included 155 male and female subjects from northern Mexico, 20–50 years of age, from low, middle, and upper income levels. Body composition was measured by ADP. Body weight (BW, kg and height (Ht, cm were obtained by standard anthropometric techniques. Resistance, R (ohms and reactance, Xc (ohms were also measured. A random-split method was used to obtain two samples: one was used to derive the equation by the "all possible regressions" procedure and was cross-validated in the other sample to test predicted versus measured values of fat-free mass (FFM. Results and Discussion The final model was: FFM (kg = 0.7374 * (Ht2 /R + 0.1763 * (BW - 0.1773 * (Age + 0.1198 * (Xc - 2.4658. R2 was 0.97; the square root of the mean square error (SRMSE was 1.99 kg, and the pure error (PE was 2.96. There was no difference between FFM predicted by the new equation (48.57 ± 10.9 kg and that measured by ADP (48.43 ± 11.3 kg. The new equation did not differ from the line of identity, had a high R2 and a low SRMSE, and showed no significant bias (0.87 ± 2.84 kg. Conclusion The new bioelectrical impedance equation based on the two-compartment model (2C was accurate, precise, and free of bias. This equation can be used to assess body composition and nutritional status in populations similar in anthropometric and physical characteristics to this sample.

  11. Impact of hemodialysis on dual X-ray absorptiometry, bioelectrical impedance measurements, and anthropometry

    DEFF Research Database (Denmark)

    Abrahamsen, Bo; Hansen, T B; Høgsberg, I M;

    1996-01-01

    Dual X-ray absorptiometry (DXA) performs noninvasive assessment of bone and soft tissue with high precision. However, soft tissue algorithms assume that 73.2% of the lean body mass is water, a potential source of error in fluid retention. We evaluated DXA (model QDR-2000; Hologic Inc, Waltham, MA......), bioelectrical impedance analysis (BIA), and simple anthropometry in 19 patients (9 women and 10 men, mean age 46 y) before and after hemodialysis, removing 0.9-4.3 L (x: 2.8L) of ultrafiltrate. The reduction in fat-free mass (FFM) measured by DXA was highly correlated with the ultrafiltrate, as determined...

  12. The variations of body mass index and body fat in adult Thai people across the age spectrum measured by bioelectrical impedance analysis

    Directory of Open Access Journals (Sweden)

    Chittawatanarat K

    2011-11-01

    Full Text Available Kaweesak Chittawatanarat1,2, Sakda Pruenglampoo3, Siriphan Kongsawasdi4, Busaba Chuatrakoon4, Vibul Trakulhoon5, Winai Ungpinitpong6, Jayanton Patumanond21Department of Surgery, Faculty of Medicine, 2Clinical Epidemiology Unit, 3Research Institute for Health Sciences, 4Department of Physical Therapy, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 5Department of Surgery, Bhumibol Adulyadej Hospital, Bangkok, 6Surgical Unit, Surin Hospital, Surin, ThailandBackground: The measurements of body mass index (BMI and percentage of body fat are used in many clinical situations. However, special tools are required to measure body fat. Many formulas are proposed for estimation but these use constant coefficients of age. Age spectrum might affect the predicted value of the body composition due to body component alterations, and the coefficient of age for body fat prediction might produce inconsistent results. The objective of this study was to identify variations of BMI and body fat across the age spectrum as well as compare results between BMI predicted body fat and bioelectrical impedance results on age.Methods: Healthy volunteers were recruited for this study. Body fat was measured by bioelectrical impedance. The age spectrum was divided into three groups (younger: 18–39.9; middle: 40–59.9; and older: ≥60 years. Comparison of body composition covariates including fat mass (FM, fat free mass (FFM, percentage FM (PFM, percentage FFM (PFFM, FM index (FMI and FFM index (FFMI in each weight status and age spectrum were analyzed. Multivariable linear regression coefficients were calculated. Coefficient alterations among age groups were tested to confirm the effect of the age spectrum on body composition covariates. Measured PFM and calculated PFM from previous formulas were compared in each quarter of the age spectrum.Results: A total of 2324 volunteers were included in this study. The overall body composition and weight

  13. Study of cystatin C (Cys C in relation to the calculation of the glomerular filtration rate and bioelectrical impedance analysis parameters in obese patients with and without type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Mario Liani

    2012-01-01

    Full Text Available IntroductionAssessment of renal function based on quantification of the glomerular filtration rate (GFR is essential for early detection of damage and progression of renal diseases. The purpose of our study was to determine the value of cystatin C (Cys C assays in the calculation of the GFR and bioelectrical impedance analysis parameters in obese subjects aged 30-70 years with moderately damaged renal function.Materials and methodsCys C levels were measured with a new immunoturbidimetric kit (Roche Diagnostics and an automated Cobas c6000 analyzer. In the GFR calculation, creatinine and Cys C levels were included. The GFR calculated with the equation that included Cys C in obese and normal-weight patients is not affected by changes in the lean body mass.ResultsObese patients (N = 70 had a mean (± SD serum creatinine level of 1.52 ± 1.0 mg/dL and a mean Cys C level of 1.28 ± 0.59 mg/L. In this group, the GFR calculated on the basis of MDRD, Cys C, and creatinine clearance values showed similar filtered values between MDRD and Cys C and a DS value smaller in the case of Cys C. The correlation (R2 between GFR and its metabolite is higher in the case of Cys C when somatotype parameters (measured with bioelectrical impedance analysis were introduced into the equation.ConclusionsWhen Cys C is included in calculations of GFR, the result shows a higher correlation degree compared to the MDRD system. Given that Cys C shows less intra-individual variability than creatinine, it can be applied in routine diagnostics in a larger number of patients.

  14. Prediction of fat-free body mass from bioelectrical impedance among 9- to 11-year-old Swedish children

    DEFF Research Database (Denmark)

    Nielsen, Birgit Marie; Dencker, M; Ward, L;

    2007-01-01

    AIM: Predictive equations for estimating body composition from bioelectrical impedance analysis (BIA) among Scandinavian children are lacking. In the present study, equations for estimation of fat-free body mass (FFM) and lean tissue mass (LTM) were developed and cross-validated from BIA using dual......-energy X-ray absorptiometry (DXA) as the reference measurement of body composition. METHODS: The study population consisted of 49 girls and 52 boys aged 9-11 years from Malmö, Sweden. Bioelectrical impedance was measured between hand and foot at 50 kHz. Predictive equations were developed by multiple......-validation revealed a mean RMSE = 0.95 kg FFM and a mean RMSE = 0.96 kg LTM. Prediction of body composition from equations developed in previous literature was mixed when applied to the present cohort of children. CONCLUSIONS: FFM and LTM are predicted with sufficient accuracy at the population level. We recommend...

  15. A comparison of skinfolds and leg-to-leg bioelectrical impedance for the assessment of body composition in children

    Science.gov (United States)

    Goss, Fredric; Robertson, Robert; Williams, Allison; Sward, Kathy; Abt, Kristi; Ladewig, Melissa; Timmer, Jeffrey; Dixon, Curt

    2003-01-01

    Background This field-based investigation examined the congruence between skinfolds and bioelectrical impedance in assessing body composition in children. Methods Subjects were 162 female and 160 male children 10–15 years of age. Skinfold measures obtained at the triceps and medial calf and a leg-to-leg bioelectrical impedance system were used to determine percent fat using child-specific equations. Pearson product moment correlations were performed on the percent fat values obtained using skinfolds and bioelectric impedance for the entire data set. Separate correlations were also conducted on gender and age/gender subsets. Dependent t tests were used to compare the two techniques. Results Percent fat did not differ between skinfolds and bioelectrical impedance for the total subject pool. Bioelectrical impedance overestimated percent fat in girls by 2.6% and underestimated percent fat in boys by 1.7% (p < 0.01). Correlations between skinfolds and bioelectrical impedance ranged from r = 0.51 to r = 0.90. Conclusions Leg-to-leg bioelectrical impedance may be a viable alternative field assessment technique that is comparable to skinfolds. The small differences in percent fat between the two techniques may have limited practical significance in school-based health-fitness settings. PMID:14498990

  16. 应用生物电阻抗法测定体育专业学生身体成分%Determination of compsitionof students' body of physical education specialty with bioelectrical impedance analysis

    Institute of Scientific and Technical Information of China (English)

    郭玉萍

    2011-01-01

    By using bioelectrical impedance analysis,major students' body composition of physical education are tested and analysed in this research.The results show that the fatfree mass of the students is insufficient,while the body fat mass is surplus and the body compsition of the students is unreasonable.A suggestion is made that the students should increase the muscular strength practice,and at the same time balance their nutrition of meals.The students' physical fitness can be improved.%应用生物电阻抗法,对体育专业学生进行了身体成分的测评与分析。结果显示,学生瘦体重不足,体脂肪率偏高,体成分不合理。建议制定科学合理的运动训练方案,增强肌肉力量性练习,配合膳食营养,改善学生体质状况。

  17. Bioelectrical impedance spectroscopy for the assessment of body fluid volumes of term neonates

    Directory of Open Access Journals (Sweden)

    Ferreira D.M.

    2004-01-01

    Full Text Available The assessment of fluid volume in neonates by a noninvasive, inexpensive, and fast method can contribute significantly to increase the quality of neonatal care. The objective of the present study was to calibrate an acquisition system and software to estimate the bioelectrical impedance parameters obtained by a method of bioelectrical impedance spectroscopy based on step response and to develop specific equations for the neonatal population to determine body fluid compartments. Bioelectric impedance measurements were performed by a laboratory homemade instrument. The volumes were estimated in a clinical study on 30 full-term neonates at four different times during the first month of life. During the first 24 hours of life the total body water, extracellular water and intracellular water were 2.09 ± 0.25, 1.20 ± 0.19, and 0.90 ± 0.25 liters, respectively. By the 48th hour they were 1.87 ± 0.27, 1.08 ± 0.17, and 0.79 ± 0.21 liters, respectively. On the 10th day they were 2.02 ± 0.25, 1.29 ± 0.21, and 0.72 ± 0.14 liters, respectively, and after 1 month they were 2.34 ± 0.27, 1.62 ± 0.20, and 0.72 ± 0.13 liters, respectively. The behavior of the estimated volume was correlated with neonatal body weight changes, leading to a better interpretation of such changes. In conclusion, this study indicates the feasibility of bioelectrical impedance spectroscopy as a method to help fluid administration in intensive care neonatal units, and also contribute to the development of new equations to estimate neonatal body fluid contents.

  18. 生物电阻抗法在慢性肾脏病儿童营养评估中的应用%Application of bioelectrical impedance analysis in the assessment of nutritional status in children with chronic kidney disease

    Institute of Scientific and Technical Information of China (English)

    吴冬雪; 孟群; 沈颖

    2014-01-01

    目的:探讨生物电阻抗原理(bioelectrical impedance analysis, BIA)在评价慢性肾脏病儿童营养方面的临床应用价值。方法选取2009年至2011年期间就诊于北京儿童医院肾脏内科的单中心慢性肾脏病(chronic kid-ney disease, CKD)患儿57例(CKD组),同时选择健康儿童54例作为正常对照组。利用生物电阻抗原理对儿童进行人体成分(主要包括蛋白质、脂肪含量的测定)的评估及比较。结果 CKD组蛋白质相对含量为(14.72±2.44)%,正常对照组为(18.10±3.91)%,两组间差异有统计学意义(t=2.61,P=0.000);CKD组脂肪相对含量为(24.31±12.52)%,显著高于正常对照组的(16.1±17.34)%,差异有统计学意义(t=3.89,P=0.000);CKD1~2期患儿蛋白质相对含量为(34.57±7.39)%,CKD3~5期患儿含量为(41.08±5.53)%,两者比较差异有统计学意义(t=3.749,P=0.000);CKD1~2期患儿相对脂肪含量为(28.73±12.50)%,CKD3~5期患儿含量为(16.13±7.52)%,其差异有统计学意义(t=-4.745,P=0.000)。 CKD组中47例(82.45%)处于营养成分失衡状态;在身高别体重提示营养状况良好的32例CKD患儿中25例(78.12%)存在营养成分不均衡。结论 CKD患儿存在蛋白质、脂肪等人体成分不均衡状态,个体化、针对性的营养管理对CKD患儿的营养状况改善有一定帮助。生物电阻抗原理对于评价CKD患儿营养状况有一定的临床应用价值。%Objectives To evaluate the nutritional status of children with chronic kidney disease(CKD) by bioelec-trical impedance analysis (BIA) and explore the value of BIA in assessing the nutritional status of children with CKD. Methods Fifty-seven patients with CKD who were hospitalized in Beijing Children's Hospital from 2009 to the end of 2011 were enrolled in this study. They were classified to be stages 1-5 according to the recommendation by the National Kidney

  19. ANALYSIS OF INTERNALLY GENERATED NOISE OF BIOELECTRIC AMPLIFIERS

    Institute of Scientific and Technical Information of China (English)

    Mashhour Mustafa; Bani Amer

    2003-01-01

    This paper deals with internally generated noise of bioelectric amplifiers that are usually used for processing of bioelectric events. The main purpose of this paper is to present a procedure for analysis of the effects of internal noise generated by the active circuits and to evaluate the output noise of the author's new designed bioelectric amplifier that caused by internal effects to the amplifier circuit itself in order to compare it with the noise generated by conventional amplifiers. The obtained analysis results of internally generated noise showed that the total output noise of bioelectric active circuits does not increase when some of their resistors have a larger value. This behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors. Moreover, the new designed bioelectric amplifier has an output noise less than that for conventional amplifiers. The obtained analysis results were also experimentally verified and the final conclusions were drawn.

  20. The Comparison of Multi-frequency Bioelectrical Impedance Analysis and the MoistureMeterD Compact on Detecting Tissue Edema in Secondary Lymphedema of Upper Limb%多频生物电阻抗分析仪与接触式水份测量仪对继发性上肢淋巴水肿检测的准确性比较

    Institute of Scientific and Technical Information of China (English)

    罗毅; 严志新; 汪立; 陈佳佳; 刘宁飞

    2014-01-01

    Objective To compare the accuracy of multi -frequency bioelectrical impedance analysis and the MoistureMeterD Compact to detect tissue edema in secondary lymphedema of upper limb. Methods Eighteen patients with secondary lymphedema after radical mastectomy, treated by manual lymph drainage, were randomly selected in this study. The measurement of circumference of upper limb was determined as standard, which had an correlation analysis with multi-frequency bioelectrical impedance analysis and MoistureMeterD Compact ’s results on tissue edema change. Results Accoring to the circumference change and the measured results of multi-frequency bioelectrical impedance analysis and the MoistureMeterD Compact, the degree of lymphedema was decreased after treatment. The multifrequency bioelectrical impedance’s test results had an relatively higher correlation (r=0.579, P<0.05) with the results of the standard, comparing to the results of the MoistureMeterD Compact (r=0.490, P<0.05). Conclusion Both multi-frequency bioelectrical impedance analysis and the MoistureMeterD Compact could be used for the measurement of lymphedema of upper limb, and multifrequency bioelectrical impedance analysis have an higher accuracy in the measurement of tissue edema.%目的:以周径测量结果为标准,比较多频生物电阻抗分析仪与接触式水分测量仪检测继发性上肢淋巴水肿的准确性。方法随机选取在我科进行淋巴手法引流治疗乳腺癌根治术后继发性上肢淋巴水肿患者18名,以周径测量获得的上肢增粗程度为标准,将多频生物电阻抗分析仪和接触式水分测量仪对组织水肿的检测结果,与周径改变进行相关性分析。结果患肢周径变化和两种水分测量的结果均显示患者治疗后水肿程度减轻。相比接触式水分测量仪的结果(r=0.490,P<0.05),多频生物电阻抗分析仪的测试结果(r=0.579,P<0.05)与周径测量结果相关性系数更高

  1. Predictive validity of four bioelectrical impedance equations in determining percent fat mass in overweight and obese children.

    Science.gov (United States)

    Cleary, Jane; Daniells, Suzie; Okely, Anthony D; Batterham, Marijka; Nicholls, Jessie

    2008-01-01

    Bioelectrical impedance equations are frequently used by food and nutrition professionals to estimate percent fat mass in overweight and obese children. However, it is not known whether they are accurate for such children, as they have been primarily developed for children of varying body weights. The aim of this cross-sectional study was to evaluate the predictive validity of four previously published prediction equations developed for the pediatric population, among a sample of overweight and obese children. Thirty overweight or obese children (mean age=7.57+/-1.28 years) underwent measurement of fat mass, percent fat mass, and fat-free mass using dual-energy x-ray absorptiometry (DEXA) and bioelectrical impedance analysis (BIA). Impedance values from the BIA were entered into the four prediction equations and Pearson correlations used to determine the significance of associations between each of the BIA prediction equations and DEXA for percent fat mass, fat mass, and fat-free mass. For percent fat mass, paired t tests were used to assess differences between the methods and the technique of Bland and Altman was used to determine bias and error. Results showed that the mean percent fat mass as determined by DEXA for this age group was 40.79%. In comparison with other BIA prediction equations, the Schaefer equation had the closest mean value of 41.98%, and was the only equation not to significantly differ from the DEXA (P=0.121). This study suggests that the Schaefer equation is the only accurate BIA prediction equation for assessing percent fat mass in this sample of overweight and obese children from primarily white backgrounds. PMID:18156000

  2. 应用生物电阻抗法评估维持性血液透析患者营养状况%Application of Bioelectrical Impedance Analysis in Patients under Maintenance Hemodialysis

    Institute of Scientific and Technical Information of China (English)

    洪海兰; 王莲凤; 杨彩娟; 黄冬玲

    2012-01-01

    目的:应用生物电阻抗法(BIA)评估维持性血液透析(MHD)患者的营养状况,为临床采取有效的营养干预提供科学依据.方法:测量56例MHD患者与60名健康志愿者的体重(WT)、体质指数(BMI)、体脂肪量(FM)、瘦体重(LBM)(即非脂肪量FFM)和体脂肪率(Fat%),用描述性研究的方法分析不同的性别、年龄及BMI的MHD患者的人体成分.结果:MHD患者人体成分的各项参数值均显著低于健康志愿者.在体质指数无显著差异的前提下,男性MHD患者的FM和Fat%低于女性,≥45岁的MHD患者FM和Fat%明显高于<45岁的患者.比较不同BMI的MHD患者的人体成分也存在显著差异.结论:应用BIA测定MHD患者的人体成分准确、无创、快捷,对有效评估MHD患者的营养状况有着重要意义.%Objective: Bioelectrical impedance analysis( BIA) was applied to assess nutritional status of maintenance hemodialysis patients( MHD) ,to provide a scientific basis for clinical effective nutrition intervention. Methods:56 cases of MHD patients and 60 healthy volunteers were involved,weight(WT) ,body mass index(BMI) ,fat mass(FM) ,lean body mass(LBM) (that is,fat -free mass,FFM)and body fat percentage were measured. Descriptive research method was used to analyze different gender, age and BMI in MHD patients of different body composition. Results:MHD patients of the body composition were significantly lower than healthy volunteers. Based tin ao significant difference in body mass index, FM and Fat % of male MHD patients were less than that of women, FM and Fat% of patients more than 45 years old were higher than that of the patients less than 45. Comparing the body composition among MHD patients with different BMI, there are significant differences. Conclusion-. Application of BIA in MHD patients was accurate,non - invasive and quick and it has important significance for assessment of the nutritional status of MHD patients.

  3. A comparison between handgrip strength, upper limb fat free mass by segmental bioelectrical impedance analysis (SBIA) and anthropometric measurements in young males

    International Nuclear Information System (INIS)

    The mechanical function and size of a muscle may be closely linked. Handgrip strength (HGS) has been used as a predictor of functional performing. Anthropometric measurements have been made to estimate arm muscle area (AMA) and physical muscle mass volume of upper limb (ULMMV). Electrical volume estimation is possible by segmental BIA measurements of fat free mass (SBIA-FFM), mainly muscle-mass. Relationship among these variables is not well established. We aimed to determine if physical and electrical muscle mass estimations relate to each other and to what extent HGS is to be related to its size measured by both methods in normal or overweight young males. Regression analysis was used to determine association between these variables. Subjects showed a decreased HGS (65.5%), FFM, (85.5%) and AMA (74.5%). It was found an acceptable association between SBIA-FFM and AMA (r2 = 0.60) and poorer between physical and electrical volume (r2 = 0.55). However, a paired Student t-test and Bland and Altman plot showed that physical and electrical models were not interchangeable (pt2 = 0.07) and electrical (r2 = 0.192) ULMMV showing that muscle mass quantity does not mean muscle strength. Other factors influencing HGS like physical training or nutrition require more research.

  4. A comparison between handgrip strength, upper limb fat free mass by segmental bioelectrical impedance analysis (SBIA) and anthropometric measurements in young males

    Science.gov (United States)

    Gonzalez-Correa, C. H.; Caicedo-Eraso, J. C.; Varon-Serna, D. R.

    2013-04-01

    The mechanical function and size of a muscle may be closely linked. Handgrip strength (HGS) has been used as a predictor of functional performing. Anthropometric measurements have been made to estimate arm muscle area (AMA) and physical muscle mass volume of upper limb (ULMMV). Electrical volume estimation is possible by segmental BIA measurements of fat free mass (SBIA-FFM), mainly muscle-mass. Relationship among these variables is not well established. We aimed to determine if physical and electrical muscle mass estimations relate to each other and to what extent HGS is to be related to its size measured by both methods in normal or overweight young males. Regression analysis was used to determine association between these variables. Subjects showed a decreased HGS (65.5%), FFM, (85.5%) and AMA (74.5%). It was found an acceptable association between SBIA-FFM and AMA (r2 = 0.60) and poorer between physical and electrical volume (r2 = 0.55). However, a paired Student t-test and Bland and Altman plot showed that physical and electrical models were not interchangeable (pt<0.0001). HGS showed a very weak association with anthropometric (r2 = 0.07) and electrical (r2 = 0.192) ULMMV showing that muscle mass quantity does not mean muscle strength. Other factors influencing HGS like physical training or nutrition require more research.

  5. Prediction of extracellular water and total body water by multifrequency bio-electrical impedance in a Southeast Asian population

    NARCIS (Netherlands)

    Guricci, S.; Hatriyanti, Y.; Hautvast, J.G.A.J.; Deurenberg, P.

    1999-01-01

    Three different adult Indonesian population groups living on Sumatra (Palembang), Java (Depok) and Sulawesi (Makale) participated in a study on body composition. Body weight, body height and multifrequency bioelectrical impedance (1, 5, 50 and 100 kHz) were measured and in addition total body water

  6. Measurement errors in multifrequency bioelectrical impedance analyzers with and without impedance electrode mismatch

    International Nuclear Information System (INIS)

    The purpose of this study is to compare measurement errors in two commercially available multi-frequency bioimpedance analyzers, a Xitron 4000B and an ImpediMed SFB7, including electrode impedance mismatch. The comparison was made using resistive electrical models and in ten human volunteers. We used three different electrical models simulating three different body segments: the right-side, leg and thorax. In the electrical models, we tested the effect of the capacitive coupling of the patient to ground and the skin–electrode impedance mismatch. Results showed that both sets of equipment are optimized for right-side measurements and for moderate skin–electrode impedance mismatch. In right-side measurements with mismatch electrode, 4000B is more accurate than SFB7. When an electrode impedance mismatch was simulated, errors increased in both bioimpedance analyzers and the effect of the mismatch in the voltage detection leads was greater than that in current injection leads. For segments with lower impedance as the leg and thorax, SFB7 is more accurate than 4000B and also shows less dependence on electrode mismatch. In both devices, impedance measurements were not significantly affected (p > 0.05) by the capacitive coupling to ground

  7. Measurement errors in multifrequency bioelectrical impedance analyzers with and without impedance electrode mismatch.

    OpenAIRE

    Bogónez Franco, Francisco; Nescolarde Selva, Lexa Digna; Bragós Bardia, Ramon; Rosell Ferrer, Francisco Javier; Yandiola, Iñigo

    2009-01-01

    The purpose of this study is to compare measurement errors in two commercially available multi-frequency bioimpedance analyzers, a Xitron 4000B and an ImpediMed SFB7, including electrode impedance mismatch. The comparison was made using resistive electrical models and in ten human volunteers. We used three different electrical models simulating three different body segments: the right-side, leg and thorax. In the electrical models, we tested the effect of the capacitive coupling of the ...

  8. A high-speed bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method

    Science.gov (United States)

    Li, Nan; Xu, Hui; Wang, Wei; Zhou, Zhou; Qiao, Guofeng; D-U Li, David

    2013-06-01

    A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz-10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications.

  9. A high-speed bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method

    International Nuclear Information System (INIS)

    A novel bioelectrical impedance spectroscopy system based on the digital auto-balancing bridge method improved from the conventional analogue auto-balancing method is presented for bioelectrical impedance measurements. The hardware of the proposed system consists of a reference source, a null detector, a variable source, a field programmable gate array, a clock generator, a flash and a USB controller. Software implemented in the field programmable gate array includes three major blocks: clock management, peripheral control and digital signal processing. The principle and realization of the least-mean-squares-based digital auto-balancing algorithm is introduced in detail. The performances of our system were examined by comparing with a commercial impedance analyzer. The results reveal that the proposed system has high speed (less than 3.5 ms per measurement) and high accuracy in the frequency range of 1 kHz–10 MHz. Compared with the commercial instrument based on the traditional analogue auto-balancing method, our system shows advantages in measurement speed, compactness and flexibility, making it suitable for various bioelectrical impedance measurement applications. (paper)

  10. A Pilot Randomized Trial Evaluating Lymphedema Self-Measurement with Bioelectrical Impedance, Self-Care Adherence, and Health Outcomes

    OpenAIRE

    Ridner, Sheila H.; Shih, Ya-Chen Tina; Doersam, Jennifer K.; Rhoten, Bethany Andrews; Schultze, Benjamin S.; Dietrich, Mary S.

    2014-01-01

    Background: Less than half of breast cancer survivors with lymphedema perform self-care as directed. Effective lymphedema self-care is required to obtain acceptable health outcomes. Self-Regulation Theory suggests that objective self-measurement of physiological conditions is necessary to promote self-regulation/self-care. Bioelectric Impedance Spectroscopy (BIS) represents a potential self-measurement method for arm lymphedema. The purpose of this pilot study was to examine the impact of arm...

  11. Association between muscle hydration measures acquired using bioelectrical impedance spectroscopy and magnetic resonance imaging in healthy and hemodialysis population

    OpenAIRE

    Sawant, Anuradha; House, Andrew A; Chesworth, Bert M.; Connelly, Denise M.; Lindsay, Robert; Gati, Joe; Bartha, Robert; Overend, Tom J.

    2015-01-01

    Abstract Establishing the effect of fluctuating extracellular fluid (ECF) volume on muscle strength in people with end‐stage renal disease (ESRD) on hemodialysis (HD) is essential, as inadequate hydration of the skeletal muscles impacts its strength and endurance. Bioelectrical impedance spectroscopy (BIS) has been a widely used method for estimating ECF volume of a limb or calf segment. Magnetic resonance imaging (MRI)‐acquired transverse relaxation times (T 2) has also been used for estimat...

  12. Reliability of Calf Bioelectrical Impedance Spectroscopy and Magnetic-Resonance-Imaging-Acquired Skeletal Muscle Hydration Measures in Healthy People

    OpenAIRE

    Anuradha Sawant; House, Andrew A; Chesworth, Bert M.; Joseph Gati; Robert Lindsay; Connelly, Denise M.; Robert Bartha; Overend, Tom J.

    2013-01-01

    Purpose. The purpose of this study was to investigate the test-retest reliability, relative variability, and agreement between calf bioelectrical impedance-spectroscopy (cBIS) acquired extracellular fluid (ECF), intracellular fluid (ICF), total water and the ratio of ECF : ICF, magnetic-resonance-imaging (MRI) acquired transverse relaxation times (T2), and apparent diffusion coefficient (ADC) of calf muscles of the same segment in healthy individuals. Methods. Muscle hydration measures were c...

  13. Foot-to-foot bioelectrical impedance accurately tracks direction of adiposity change in overweight and obese 7- to 13-year-old children.

    Science.gov (United States)

    Kasvis, Popi; Cohen, Tamara R; Loiselle, Sarah-Ève; Kim, Nicolas; Hazell, Tom J; Vanstone, Catherine A; Rodd, Celia; Plourde, Hugues; Weiler, Hope A

    2015-03-01

    Body composition measurements are valuable when evaluating pediatric obesity interventions. We hypothesized that foot-to-foot bioelectrical impedance analysis (BIA) will accurately track the direction of adiposity change, but not magnitude, in part due to differences in fat patterning. The purposes of this study were to examine the accuracy of body composition measurements of overweight and obese children over time using dual-energy x-ray absorptiometry (DXA) and BIA and to determine if BIA accuracy was affected by fat patterning. Eighty-nine overweight or obese children (48 girls, 41 boys, age 7-13 years) participating in a randomized controlled trial providing a family-centered, lifestyle intervention, underwent DXA and BIA measurements every 3 months. Bland-Altman plots showed a poor level of agreement between devices for baseline percent body fat (%BF; mean, 0.398%; +2SD, 8.685%; -2SD, -7.889%). There was overall agreement between DXA and BIA in the direction of change over time for %BF (difference between visits 3 and 1: DXA -0.8 ± 0.5%, BIA -0.7 ± 0.5%; P = 1.000) and fat mass (FM; difference between visits 3 and 1: DXA 0.7 ± 0.5 kg, BIA 0.6 ± 0.5 kg; P = 1.000). Bioelectrical impedance analysis measurements of %BF and FM at baseline were significantly different in those with android and gynoid fat (%BF: 35.9% ± 1.4%, 32.2% ± 1.4%, P < .003; FM: 20.1 ± 0.8 kg, 18.4 ± 0.8, P < .013). Bioelectrical impedance analysis accurately reports the direction of change in FM and FFM in overweight and obese children; inaccuracy in the magnitude of BIA measurements may be a result of fat patterning differences.

  14. ANALYSIS OF INTERNALLY GENERATED NOISE OF BIOELECTRIC AMPLIFIERS

    Institute of Scientific and Technical Information of China (English)

    MashhourMustafaBaniAmer

    2003-01-01

    This papenr deals with internally generated noise of bioelectric amplifiers that are usually used for processing of bioelectric events.The main purpose of this paper is to present a procedure for analysis of the effects of internal noise generated by the active circuits and to evaluate the output noise of the author's new designed bioelectric amplifier that caused by internal effects to the amplifier circuit itself in order to compare it with the noise generated by conventional amplifiers.The obtained analysis results of internally generated noise showed that the total output noise of bioelectric active circuits does not increase when some of their resitors have a larger value.This behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors.Moreover,the new designed bioelectric amplifier haws an output noise less than that for conventional amplifiers.The obtained analysis results were also experimentally verified and the final conclusions were drawn.

  15. Evaluation of a foot-to-foot bioelectrical impedance analyser in highly active, moderately active and less active young men.

    Science.gov (United States)

    Swartz, Ann M; Swartz, Ann M; Jeremy Evans, M; King, George A; Thompson, Dixie L

    2002-08-01

    The Tanita TBF-305 (Tanita Corp., Tokyo, Japan) is a commercially available foot-to-foot bioelectrical impedance analysis (BIA) system. The manufacturer-supplied equations incorporate gender, mass, height, activity category and a measured impedance value to determine % body fat (BF). The purpose of the present study was to determine whether the manufacturer-supplied 'adult' and 'athlete' equations provided an accurate estimate of % BF for a group of young men with varying activity levels. Fifty-seven men (18-35 years old) were categorized into the following groups: (1) highly active (HA) (> or = 10.0 h aerobic activity/week); (2) moderately active (MA) (2.5-10.0 h aerobic activity/week); (3) less active (LA) (aerobic activity/week). The % BF was measured using the BIA 'athlete' and 'adult' modes. After BIA measurements, residual volume was measured and hydrostatic weighing (HW) was performed. The amount of activity performed by each group was significantly different (P<0.001). No significant differences were found between the % BF determined by the 'athlete' mode and HW for HA (P=0.309) and MA (P=0.091). However, a significant difference was found for LA (P=0.001). The % BF determined by the 'adult' mode and HW was not different for LA (P=0.395), but was significantly different for MA (P<0.001) and HA (P<0.001). The choice of activity mode on the foot-to-foot BIA significantly alters prediction of % BF. With careful selection of activity mode, there was no statistical difference between % BF determined by HW and the BIA, but the range of individual error scores was large. PMID:12144724

  16. Body composition measures of obese adolescents by the deuterium oxide dilution method and by bioelectrical impedance

    Directory of Open Access Journals (Sweden)

    C.M.M. Resende

    2011-11-01

    Full Text Available The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA and the deuterium dilution method (DDM, to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg, fat-free mass (FFM; kg, and total body water (TBW; % determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P < 0.001, FM (r = 0.93; P < 0.001 and TBW (r = 0.62; P < 0.001. The Bland-Altman plot showed no agreement for FFM, FM or TBW between data provided by BIA and DDM. The linear regression models proposed in our study with respect to FFM, FM, and TBW were well adjusted. FFM obtained by DDM = 0.842 x FFM obtained by BIA. FM obtained by DDM = 0.855 x FM obtained by BIA + 0.152 x weight (kg. TBW obtained by DDM = 0.813 x TBW obtained by BIA. The body composition results of obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.

  17. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA

    DEFF Research Database (Denmark)

    Ejlerskov, Katrine Tschentscher; Jensen, Signe Marie; Christensen, Line B;

    2014-01-01

    For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99...... healthy 3-year-old Danish children. Predictive equations were derived from two multiple linear regression models, a comprehensive model (height(2)/resistance (RI), six anthropometric measurements) and a simple model (RI, height, weight). Their uncertainty was quantified by means of 10-fold cross...

  18. Validation of Bioelectrical Impedance Spectroscopy to Measure Total Body Water in Resistance-Trained Males.

    Science.gov (United States)

    Kerr, Ava; Slater, Gary; Byrne, Nuala; Chaseling, Janet

    2015-10-01

    The three-compartment (3-C) model of physique assessment (fat mass, fat-free mass, water) incorporates total body water (TBW) whereas the two-compartment model (2-C) assumes a TBW of 73.72%. Deuterium dilution (D2O) is the reference method for measuring TBW but is expensive and time consuming. Multifrequency bioelectrical impedance spectroscopy (BIS SFB7) estimates TBW instantaneously and claims high precision. Our aim was to compare SFB7 with D2O for estimating TBW in resistance trained males (BMI >25kg/m2). We included TBWBIS estimates in a 3-C model and contrasted this and the 2-C model against the reference 3-C model using TBWD2O. TBW of 29 males (32.4 ± 8.5 years; 183.4 ± 7.2 cm; 92.5 ± 9.9 kg; 27.5 ± 2.6 kg/m2) was measured using SFB7 and D2O. Body density was measured by BODPOD, with body composition calculated using the Siri equation. TBWBIS values were consistent with TBWD2O (SEE = 2.65L; TE = 2.6L) as were %BF values from the 3-C model (BODPOD + TBWBIS) with the 3-C reference model (SEE = 2.20%; TE = 2.20%). For subjects with TBW more than 1% from the assumed 73.72% (n = 16), %BF from the 2-C model differed significantly from the reference 3-C model (Slope 0.6888; Intercept 5.093). The BIS SFB7 measured TBW accurately compared with D2O. The 2C model with an assumed TBW of 73.72% introduces error in the estimation of body composition. We recommend TBW should be measured, either via the traditional D2O method or when resources are limited, with BIS, so that body composition estimates are enhanced. The BIS can be accurately used in 3C equations to better predict TBW and BF% in resistance trained males compared with a 2C model. PMID:26011918

  19. Are Ethnic and Gender Specific Equations Needed to Derive Fat Free Mass from Bioelectrical Impedance in Children of South Asian, Black African-Caribbean and White European Origin? Results of the Assessment of Body Composition in Children Study

    OpenAIRE

    Nightingale, Claire M; Rudnicka, Alicja R; Owen, Christopher G; Donin, Angela S.; Newton, Sian L.; Furness, Cheryl A.; Emma L Howard; Gillings, Rachel D.; Jonathan C K Wells; Cook, Derek G.; Whincup, Peter H.

    2013-01-01

    BACKGROUND: Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 ...

  20. Determination of Composition of Students'body of Physical Dducation Specialty with Bioelectrical Impedance Analysis in Heze University%运用生物电阻抗法测定菏泽学院体育专业学生身体成分的研究

    Institute of Scientific and Technical Information of China (English)

    李建萍

    2015-01-01

    By using bioelectrical impedance analysis,major students' body composition of physical education in Heze College include fat,brawn, body moisture (fluid in the cell, extracellular fluid), protein and so on carries on the research analysis and development situation of sports professional students have a detailed understanding, and for the sports college students to provide a scientific basis for rational diet. Through body composition of 270 students in physical education found that students' slightly lighter weight, higher body fat rate, body composition is not reasonable.%应用生物电阻抗法(BIA)通过对菏泽学院体育专业学生的基本身体成分院脂肪量、筋肉量、体水分(细胞內液、细胞外液)、蛋白质等进行研究分析,对体育专业的学生的营养、发育情况有了详细的了解,并为体育专业学生的合理膳食提供科学的依据。通过对体育专业的270名学生的身体成分进行研究发现,学生的体重稍轻,体脂肪率偏高,体成分不合理。

  1. A signal analysis method for bioelectrical impedance measurement of gastric motility based on HHT%基于HHT的生物电阻抗胃动力信号分析方法

    Institute of Scientific and Technical Information of China (English)

    柴林燕; 赵舒; 沙洪

    2011-01-01

    Objective The Hilbert- Huang transformation (HHT) method was introduced to process the bio-impedance gastric motility signals from subjects.Methods Nonlinear and non-stationary original gastric motility series were decomposed into a number of intrinsic mode function (1MF) components by the empirical mode decomposition method (EMD).Hilbert transformation was carried out then and instantaneous frequency was extracted effectively.Gastric motility signal among 0.03-0.06 Hz was reconstructed from the IMF.Results The results suggested that HHT was a new and applicable time series analysis method based on mode decomposition and could extract impedance signal and remove the disturbances such as blood flow and breathing.Conclusion The new adaptive mode decomposition-based signal processing method provides a new method to investigate clinical gastric motility information.%目的 采用HHT时间序列分析方法处理从人体采集到的胃动力信号.方法 通过经验模态分解(EMD)技术将一非线性、非稳态过程的原始胃动力序列分解为一组内在模态函数(IMFs),对每一个IMF进行Hilbert 变换,得到信号的瞬时频率,然后选择与胃动力相关的频率成分,即0.03-0.06 Hz之间的IMF进行重构提取胃动力信号.结果 使用该方法可以有效去除叠加在阻抗胃动力信号中的呼吸和血流等干扰信号,保留胃动力信号的有效频率成分.结论 此方法是一种更具有自适应的、新型的、基于模态分解的时间序列数据处理方法,可以有效地为临床胃动力信息研究提供一种新途径.

  2. Bioelectrical impedance spectroscopy as a fluid management system in heart failure

    International Nuclear Information System (INIS)

    Episodes of hospitalization for heart failure patients are frequent and are often accompanied by fluid accumulations. The change of the body impedance, measured by bioimpendace spectroscopy, is an indicator of the water content. The hypothesis was that it is possible to detect edema from the impedance data. First, a finite integration technique was applied to test the feasibility and allowed a theoretical analysis of current flows through the body. Based on the results of the simulations, a clinical study was designed and conducted. The segmental impedances of 25 patients suffering from heart failure were monitored over their recompensation process. The mean age of the patients was 73.8 and their mean body mass index was 28.6. From these raw data the model parameters from the Cole model were deduced by an automatic fitting algorithm. These model data were used to classify the edema status of the patient. The baseline values of the regression lines of the extra- and intracellular resistance from the transthoracic measurement and the baseline value of the regression line of the extracellular resistance from the foot-to-foot measurement were identified as important parameters for the detection of peripheral edema. The rate of change of the imaginary impedance at the characteristic frequency and the mean intracellular resistance from the foot-to-foot measurement were identified as important parameters for the detection of pulmonary edema. To classify the data, two decision trees were considered: One should detect pulmonary edema (npulmonary = 13, nnone = 12) and the other peripheral edema (nperipheral = 12, nnone = 13). Peripheral edema could be detected with a sensitivity of 100% and a specificity of 90%. The detection of pulmonary edema showed a sensitivity of 92.31% and a specificity of 100%. The leave-one-out cross-validation-error for the peripheral edema detection was 12% and 8% for the detection of pulmonary edema. This enables the application of BIS as an early

  3. Single-cell bioelectrical impedance platform for monitoring cellular response to drug treatment

    OpenAIRE

    Asphahani, Fareid; Wang, Kui; Thein, Myo; Veiseh, Omid; Yung, Sandy; Xu, Jian; Zhang, Miqin

    2011-01-01

    The response of cells to a chemical or biological agent in terms of their impedance changes in real-time is a useful mechanism that can be utilized for a wide variety of biomedical and environmental applications. The use of a single-cell based analytical platform could be an effective approach to acquiring more sensitive cell impedance measurements, particularly in applications where only diminutive changes in impedance are expected. Here, we report the development of an on-chip cell impedanc...

  4. Influence of Posture and Frequency Modes in Total Body Water Estimation Using Bioelectrical Impedance Spectroscopy in Boys and Adult Males

    Directory of Open Access Journals (Sweden)

    Masaharu Kagawa

    2014-05-01

    Full Text Available The aim of the study was to examine differences in total body water (TBW measured using single-frequency (SF and multi-frequency (MF modes of bioelectrical impedance spectroscopy (BIS in children and adults measured in different postures using the deuterium (2H dilution technique as the reference. Twenty-three boys and 26 adult males underwent assessment of TBW using the dilution technique and BIS measured in supine and standing positions using two frequencies of the SF mode (50 kHz and 100 kHz and the MF mode. While TBW estimated from the MF mode was comparable, extra-cellular fluid (ECF and intra-cellular fluid (ICF values differed significantly (p < 0.01 between the different postures in both groups. In addition, while estimated TBW in adult males using the MF mode was significantly (p < 0.01 greater than the result from the dilution technique, TBW estimated using the SF mode and prediction equation was significantly (p < 0.01 lower in boys. Measurement posture may not affect estimation of TBW in boys and adult males, however, body fluid shifts may still occur. In addition, technical factors, including selection of prediction equation, may be important when TBW is estimated from measured impedance.

  5. DESCRIPTIVE PROFILE OF BODY STRUCTURE OF TOP GRECO-ROMAN STYLE WRESTLERS DEFINED WITH METHOD OF MULTICHANNEL BIOELECTRIC IMPEDANCE

    Directory of Open Access Journals (Sweden)

    Milivoj Dopsaj

    2012-12-01

    Full Text Available Because of the specificity of given sport and weight categories wrestlers are characterized by specific morphologic characteristics. With the development of new measurement technologies there are some new opportunities for the development of new ways of obtaining information relevant to the sports system. One of the new technologies, which are used in area of measurement of body composition structure, is a method of bioimpedace, and the latest generations use a variant of the multichannel bioelectrical bioimpedance. The goal of this study is to define morphological model of top senior wrestlers by using the latest technological methods that will revalidate the existing knowledge about the given area. The sample of respondents is made of 22 male wrestlers, Greco-Roman style, top senior level athletes from four different countries: Serbia (n = 10, Croatia (n = 9, Montenegro (n = 2 and Greece (n = 1. Measurement of body composition is made with method of multichannel bioelectric impedance with professional apparatus of latest generation - InBody 720 Tetrapolar 8-Point Tactile Electrode System (Biospace, Co., Ltd. The most important result of this research is definition of generic (general four-dimensional model (4D model of body composition with quality international level wrestlers with following characteristics: in regards to average body mass of sample wrestlers – 81.95 kg, the amount of water is 55.08 L or 67.24 %, the amount of proteins is 15.00 kg or 18.33%, minerals 4.98 kg or 5.97% and fat mass 6.99 kg or 8.49 %.

  6. Body composition of Bangladeshi children: comparison and development of leg-to-leg bioelectrical impedance equation.

    Science.gov (United States)

    Khan, Ashraful I; Hawkesworth, Sophie; Hawlader, Mohammad Delwer Hossain; El Arifeen, Shams; Moore, Sophie; Hills, Andrew P; Wells, Jonathan C; Persson, Lars-Åke; Kabir, Iqbal

    2012-09-01

    The aim of this study was to investigate the validity of the Tanita TBF 300A leg-to-leg bioimpedance analyzer for estimating fat-free mass (FFM) in Bangladeshi children aged 4-10 years and to develop novel prediction equations for use in this population, using deuterium dilution as the reference method. Two hundred Bangladeshi children were enrolled. The isotope dilution technique with deuterium oxide was used for estimation of total body water (TBW). FFM estimated by Tanita was compared with results of deuterium oxide dilution technique. Novel prediction equations were created for estimating FFM, using linear regression models, fitting child's height and impedance as predictors. There was a significant difference in FFM and percentage of body fat (BF%) between methods (pmodel with height and impedance explained 83% of the variance in FFM estimated by deuterium oxide dilution technique. The best-fit equation to predict FFM from linear regression modelling was achieved by adding weight, sex, and age to the basic model, bringing the adjusted R² to 89% (standard error=0.90, p<0.001). These data suggest Tanita analyzer may be a valid field-assessment technique in Bangladeshi children when using population-specific prediction equations, such as the ones developed here.

  7. Reliability of Calf Bioelectrical Impedance Spectroscopy and Magnetic-Resonance-Imaging-Acquired Skeletal Muscle Hydration Measures in Healthy People

    Directory of Open Access Journals (Sweden)

    Anuradha Sawant

    2013-01-01

    Full Text Available Purpose. The purpose of this study was to investigate the test-retest reliability, relative variability, and agreement between calf bioelectrical impedance-spectroscopy (cBIS acquired extracellular fluid (ECF, intracellular fluid (ICF, total water and the ratio of ECF : ICF, magnetic-resonance-imaging (MRI acquired transverse relaxation times (T2, and apparent diffusion coefficient (ADC of calf muscles of the same segment in healthy individuals. Methods. Muscle hydration measures were collected in 32 healthy individuals on two occasions and analyzed by a single rater. On both occasions, MRI measures were collected from tibialis anterior (TA, medial (MG, and lateral gastrocnemius (LG and soleus muscles following the cBIS data acquired using XiTRON Hydra 4200 BIS device. The intraclass correlation coefficients (ICC2,1, coefficient of variation (CV, and agreement between MRI and cBIS data were also calculated. Results. ICC2,1 values for cBIS, T2, and ADC ranged from 0.56 to 0.92, 0.96 to 0.99, and 0.05 to 0.56, respectively. Relative variability between measures (CV ranged from 14.6 to 25.6% for the cBIS data and 4.2 to 10.0% for the MRI-acquired data. The ratio of ECF : ICF could significantly predict T2 of TA and soleus muscles. Conclusion. MRI-acquired measures of T2 had the highest test-retest reliability of muscle hydration with the least error and variation on repeated testing. Hence, T2 of a muscle is the most reliable and stable outcome measure for evaluating individual muscle hydration.

  8. Use of electrocardiogram (ECG) electrodes for Bioelectrical Impedance Analysis (BIA)

    International Nuclear Information System (INIS)

    BIA is a safe, noninvasive, portable and relatively inexpensive method of estimating body composition that is practical and suitable for individual use and large-scale studies. However, the cost of the electrodes recommended by some BIA manufacturers is too high for developing countries; where very often the long and complicated process of importation reduces the time they can be used. The purpose of this study was to evaluate the use of two types of ECG electrodes (2290 and 2228 by 3M®) in BIA measurements to decrease the costs of the test. The results showed that the 2228 ECG electrodes can be used in BIA measurements for adult's body composition assessment. These electrodes are available in the domestic market and their costs are 92% lower than the electrodes recommended by manufacturer. The results show a new cost-benefit relation for BIA method and make this a more accessible tool for individual tests, large-scale researches and studies in the community.

  9. Performance of Two Bioelectrical Impedance Analyses in the Diagnosis of Overweight and Obesity in Children and Adolescents: The FUPRECOL Study

    Directory of Open Access Journals (Sweden)

    Robinson Ramírez-Vélez

    2016-10-01

    Full Text Available This study aimed to determine thresholds for percentage of body fat (BF% corresponding to the cut-off values for overweight/obesity as recommended by the International Obesity Task Force (IOTF, using two bioelectrical impedance analyzers (BIA, and described the likelihood of increased cardiometabolic risk in our cohort defined by the IOTF and BF% status. Participants included 1165 children and adolescents (54.9% girls from Bogotá (Colombia. Body mass index (BMI was calculated from height and weight. BF% of each youth was assessed first using the Tanita BC-418® followed by a Tanita BF-689®. The sensitivity and specificity of both devices and their ability to correctly classify children as overweight/obesity (≥2 standard deviation, as defined by IOTF, was investigated using receiver operating characteristic (ROC by sex and age groups (9–11, 12–14, and 13–17 years old; Area under curve (AUC values were also reported. For girls, the optimal BF% threshold for classifying into overweight/obesity was found to be between 25.2 and 28.5 (AUC = 0.91–0.97 and 23.9 to 26.6 (AUC = 0.90–0.99 for Tanita BC-418® and Tanita BF-689®, respectively. For boys, the optimal threshold was between 16.5 and 21.1 (AUC = 0.93–0.96 and 15.8 to 20.6 (AUC = 0.92–0.94 by Tanita BC-418® and Tanita BF-689®, respectively. All AUC values for ROC curves were statistically significant and there were no differences between AUC values measured by both BIA devices. The BF% values associated with the IOTF-recommended BMI cut-off for overweight/obesity may require age- and sex-specific threshold values in Colombian children and adolescents aged 9–17 years and could be used as a surrogate method to identify individuals at risk of excess adiposity.

  10. Performance of Two Bioelectrical Impedance Analyses in the Diagnosis of Overweight and Obesity in Children and Adolescents: The FUPRECOL Study

    Science.gov (United States)

    Ramírez-Vélez, Robinson; Correa-Bautista, Jorge Enrique; Martínez-Torres, Javier; González-Ruíz, Katherine; González-Jiménez, Emilio; Schmidt-RioValle, Jacqueline; Garcia-Hermoso, Antonio

    2016-01-01

    This study aimed to determine thresholds for percentage of body fat (BF%) corresponding to the cut-off values for overweight/obesity as recommended by the International Obesity Task Force (IOTF), using two bioelectrical impedance analyzers (BIA), and described the likelihood of increased cardiometabolic risk in our cohort defined by the IOTF and BF% status. Participants included 1165 children and adolescents (54.9% girls) from Bogotá (Colombia). Body mass index (BMI) was calculated from height and weight. BF% of each youth was assessed first using the Tanita BC-418® followed by a Tanita BF-689®. The sensitivity and specificity of both devices and their ability to correctly classify children as overweight/obesity (≥2 standard deviation), as defined by IOTF, was investigated using receiver operating characteristic (ROC) by sex and age groups (9–11, 12–14, and 13–17 years old); Area under curve (AUC) values were also reported. For girls, the optimal BF% threshold for classifying into overweight/obesity was found to be between 25.2 and 28.5 (AUC = 0.91–0.97) and 23.9 to 26.6 (AUC = 0.90–0.99) for Tanita BC-418® and Tanita BF-689®, respectively. For boys, the optimal threshold was between 16.5 and 21.1 (AUC = 0.93–0.96) and 15.8 to 20.6 (AUC = 0.92–0.94) by Tanita BC-418® and Tanita BF-689®, respectively. All AUC values for ROC curves were statistically significant and there were no differences between AUC values measured by both BIA devices. The BF% values associated with the IOTF-recommended BMI cut-off for overweight/obesity may require age- and sex-specific threshold values in Colombian children and adolescents aged 9–17 years and could be used as a surrogate method to identify individuals at risk of excess adiposity. PMID:27782039

  11. A comparison of fat mass and skeletal muscle mass estimation in male ultra-endurance athletes using bioelectrical impedance analysis and different anthropometric methods Comparación de la masa grasa y muscular estimada en atletas varones de ultra-resistencia utilizando la bioimpedancia eléctrica y diferentes métodos antropométricos

    Directory of Open Access Journals (Sweden)

    B. Knechtle

    2011-12-01

    Full Text Available Two hundred and fifty seven male Caucasian ultraendurance athletes were recruited, pre-race, before different swimming, cycling, running and triathlon races. Fat mass and skeletal muscle mass were estimated using bioelectrical impedance analysis (BIA and anthropometric methods in order to investigate whether the use of BIA or anthropometry would be useful under field conditions. Total body fat estimated using BIA was significantly high (P Se reclutaron a 257 hombres caucasianos que eran atletas de alto rendimiento, antes de competir en diferentes pruebas triatlón de natación, ciclismo y carrera. Se estimaron la masa grasa y la masa de músculo esquelético utilizando un análisis de impedancia bioeléctrica (BIA y métodos antropométricos con el fin de investigar si el uso de BIA o de la antropometría sería útil en tales condiciones de campo. La grasa corporal total estimada por BIA fue significativamente mayor en comparación con la antropometría (P < 0,001. Cuando se compararon los resultados entre BIA y antropometría, se encontraron niveles de concordancia bajos a moderados. Estos resultados concuerdan con las diferencias halladas con el análisis Bland-Altman, lo que indica que la ecuación antropométrica de Ball et al. posee el mayor grado de concordancia (desviación = -3,0 ± 5,8 kg con BIA, con Stewart et al. (desviación = -6,4 ± 6,3 kg, Faulkner (desviación = -4,7 ± 5,8 kg y Wilmore-Siri (desviación = -4,8 ± 6,2 kg. La estimación de la masa de músculo esquelético fue significativamente superior con BIAS que con antropometría (P < 0,001. Los resultados de la ICC y del método Bland-Altman muestran que la ecuación antropométrica de Lee et al. (desviación = -5,4 ± 5,3 kg produjo el mayor grado de concordancia. El método combinado de Janssen et al. entre antropometría y BIA mostró el menor grado de concordancia (desviación = -12,5 ± 5,7 kg. Hubo una diferencia estadísticamente significativa entre los resultados

  12. A Comparison Study of Portable Foot-to-Foot Bioelectrical Impedance Scale to Measure Body Fat Percentage in Asian Adults and Children

    Directory of Open Access Journals (Sweden)

    Pei Ying Sim

    2014-01-01

    Full Text Available Objective. To compare the measurements of body fat percentage (BF% using the foot-to-foot bioelectrical impedance analysis (FTF-BIA with the direct segmental multifrequency BIA (DSM-BIA. Methods. There were 36 men and 52 women (37.1±14.3 years with 57% Malays, 30% Chinese, and 13% Indian. For children, there were 45 boys and 26 girls (11.5±2.5 years with 52% Malay, 15% Chinese, and 33% Indian. Results. Mean height for men was 168.4 cm, 11 cm taller than women. Men were 10 kg heavier than women at 70 kg. BF% in women was 32% and 33% whereas BF% in men was 23% and 25% when measured using FTF-BIA and DSM-BIA, respectively. In children, BF% measured with FTF-BIA and DSM-BIA was 49% and 46%, respectively. The correlations were significant for men (r=0.92, SEE = 2.80, women (r=0.91, SEE = 3.31, boys (r=0.95, SEE = 5.44, and girls (r=0.96, SEE = 5.27. The BF% in underweight/normal (r=0.92, SEE = 2.47 and that in overweight/obese adults (r=0.89, SEE = 3.61 were strongly correlated. The correlations were significant in normal/underweight (r=0.94, SEE = 3.78 and obese/overweight children (r=0.83, SEE = 6.49. All ethnic groups showed significant correlation with BF%. Malay adults (r=0.92, SEE = 3.27 and children (r=0.94, SEE = 0.88 showed significant mean differences in BF%. Conclusion. The FTF-BIA showed higher accuracy for all normal/underweight and Chinese group with acceptable overestimation in children and underestimation in adults. Caution should be taken when interpreting BF% depending on gender, BMI, and ethnicity.

  13. Establishment of muscle mass diagnostic standard of sarcopenia using a bioelectrical impedance analysis and epidemiological investigation of the elderly in Shanghai%上海地区老年人肌少症骨骼肌质量诊断标准建立和流行病学调查

    Institute of Scientific and Technical Information of China (English)

    陈敏; 白慧婧; 王纯; 王彦; 徐丹凤; 谢华; 易青; 李臻; 李茹

    2015-01-01

    目的 应用生物电阻抗法(BIA)建立上海地区老年人肌少症骨骼肌质量诊断标准并开展上海地区老年人肌少症患病率的调查.方法 对40例志愿者(年龄20~77岁)进行BIA和双能X线吸收仪(DEXA)检测,验证BIA测定瘦体组织的可靠性.对219例(年龄20~40岁)健康青年人(男∶女为100∶119)进行BIA检测,获得峰值肌量和老年人肌少症诊断切点.对657例≥60岁医院体检和社区老年人(男∶女为318∶339)进行BIA检测,了解上海地区老年人肌少症患病率.结果 BIA和DEXA检测瘦体组织差异无统计学意义(P=0.307).健康青年人四肢肌肉组织和身高平方的比值(ASM/身高2)男性和女性分别为(7.90±0.62)kg/m2和(6.12±0.44)kg/m2,老年人肌少症诊断标准男性和女性分别为≤6.66 kg/m2和≤5.24 kg/m2.将老年人分为3个年龄段,60~岁、70~岁和≥80岁3个年龄段男性肌少症的患病率分别为14.6%、25.0%和36.0%,女性分别为6.8%、12.6%和27.9%.老年男性整体患病率为23.6%,女性为11.8%.结论 BIA检测人体肌肉组织是可靠的,且随增龄肌少症患病率明显上升,男性高于女性.%Objective To establish diagnostic standard of sarcopenia using bioelectrical impedance analysis (BIA) and to obtain the prevalence of sarcopenia in the elderly in Shanghai.Methods 40 volunteers aged 20-77 years were enrolled and received BIA and dual-energy X-ray absorptiometry (DEXA) measurements in order to verify the reliability of BIA for measuring lean mass.219 healthy young volunteers aged 20 to 40 years with ratio of gender men:women 100:119 had BIA measurements to obtain peak muscle mass and sarcopenia diagnostic cut-off point of the elderly.657 elderly aged ≥ 60 years with ratio of gendermen:women 318:339 took BIA measurements to obtain the prevalence of sarcopenia in the elderly in Shanghai.Results No statistical difference between BIA-measured and DEXA-measured LM was observed (P =0.307).The

  14. Application of cardiac output measurement by bioelectrical impedance in critically ill patients%生物电阻抗法监测心输出量在危重病中的应用

    Institute of Scientific and Technical Information of China (English)

    刘紫锰; 杨春华; 陈娟; 欧阳彬; 管向东

    2009-01-01

    目的 探讨生物电阻抗法测量无创心输出量(CO)在危重病中应用的准确性和有效性.方法 选择2008年1月至5月间本院外科重症监护中心(SICU)收治的12例需放置SWAN-GANZ导管进行血流动力学监测的患者,同时用生物电阻抗法和SWAN-GANZ导管热稀释法测定患者CO曲线平稳后0、1、6、12、24、48 h的CO值,并应用Pearson相关对两种方法测得的CO值与时间进行分析.结果 生物电阻抗法测最的CO值在所有时间点均低于SWAN-GANZ导管热稀释法的测最值[0 h:(5.5±0.9)L/min比(7.7±1.4)L/min;1h:(5.3±0.7)L/min比(7.4±1.5)L/min;6 h:(4.6±0.6)L/min比(6.8±1.4)L/min;12 h:(5.1±0.9)L/min比(7.6±1.6)L/min;24 h:(6.1±1.1)L/min比(9.0±1.6)L/min;48 h:(6.3±1.3)L/min比(9.5±1.5)L/min;均P<0.05].两种方法测量的CO值均随着时间的延长而呈升高趋势(r=0.818,P=0.047和r=0.884,P=0.020).结论 生物电阻抗法测量的无创CO与SWAN-GANZ导管测定的患者CO同样呈时间依赖性,是一种有效的CO监测方法.%Objective To evaluate the efficacy and accuracy of non-invasive bioelectrical impedance measurement of cardiac output (CO) in critically ill patients. Methods Between January and May 2008, 12 patients who needed hemodynamics monitoring using SWAN-GANZ catheterization in surgical intensive care unit (SICU) of our hospital were measured for CO by bioelectrical impedance and SWAN-GANZ catheterization thermodilution approaches. These values were recorded at 0, 1, 6, 12, 24 and 48 hours after the CO curve became stable in these patients. Pearson correlation analysis was performed for CO values over time recorded by these two approaches. Results At all the time points, CO measurement by bioelectrical impedance yielded lower values than those by SWAN-GANZ catheterization thermodilution approach [0 h: (5.5±0.9) L/min vs (7.7±1.4) L/min; 1 h: (5.3±0.7) L/min vs (7.4±1.5) L/min; 6 h: (4.6±0.6) L/min vs (6.8±1.4) L/min; 12 h: (5.1±0.9) L/min vs (7.6±1.6) L

  15. Multi-frequency bioelectrical impedance: a comparison between the Cole-Cole modelling and Hanai equations with the classical impedance index approach.

    Science.gov (United States)

    Deurenberg, P; Andreoli, A; de Lorenzo, A

    1996-01-01

    Total body water and extracellular water were measured by deuterium oxide and bromide dilution respectively in 23 healthy males and 25 healthy females. In addition, total body impedance was measured at 17 frequencies, ranging from 1 kHz to 1350 kHz. Modelling programs were used to extrapolate impedance values to frequency zero (extracellular resistance) and frequency infinity (total body water resistance). Impedance indexes (height2/Zf) were computed at all 17 frequencies. The estimation errors of extracellular resistance and total body water resistance were 1% and 3%, respectively. Impedance and impedance index at low frequency were correlated with extracellular water, independent of the amount of total body water. Total body water showed the greatest correlation with impedance and impedance index at high frequencies. Extrapolated impedance values did not show a higher correlation compared to measured values. Prediction formulas from the literature applied to fixed frequencies showed the best mean and individual predictions for both extracellular water and total body water. It is concluded that, at least in healthy individuals with normal body water distribution, modelling impedance data has no advantage over impedance values measured at fixed frequencies, probably due to estimation errors in the modelled data.

  16. Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Federica Villa

    2016-05-01

    Full Text Available Bioelectrical Impedance Spectroscopy (BIS allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously.

  17. Study of Noninvasive Intracranial Pressure Monitoring by Bioelectric Impedance Method%生物电阻抗法无创监护颅内压研究

    Institute of Scientific and Technical Information of China (English)

    肖贵遐; 刘国庆; 彭玉平; 朱代谟

    2001-01-01

    The changes of intracranial components and corr esponding brain impedan ce were analyzed while intracranial pressure was increasing, and the relation of intr acranial pressure pulse wave and brain impedance pulse wave were discussed. A theory of noninvasive intracranial pressure monitoring by bioelectric impedance was put forward. The result of primary experiment suggested that the theory be feasible.%分析了在颅内压增高的过程中,颅内容 物的变化及相应的脑阻抗的变化情况 ,同时讨论了在颅内压升高以后颅内压脉冲波和脑阻抗脉冲波的关系,提出了一个用生物电 阻抗法无创监护颅内压的理论。初步的动物实验表明该理论是可行的。

  18. Analysis of Body Composition Methods in a Community Sample of African American Women

    OpenAIRE

    Lopez, Ygnacio; O’Connor, Daniel P.; Ledoux, Tracey A.; Rebecca E. Lee

    2011-01-01

    The purposes of the authors in this study were: (1) to determine whether published body mass index and bioelectrical impedance analysis equations agreed with dual energy x-ray absorptiometry body fat percentage measures and (2) to estimate new body mass index and bioelectrical impedance analysis equations in a sample of African American women. Linear regression was used to determine how well 10 body mass index and bioelectrical impedance analysis equations reflected dual energy x-ray absorpti...

  19. BODY COMPOSITION OF YOUNG PEOPLE AGED 17-18 YEARS, PRACTICING AND NOT PRACTICING SWIMMING, WITH THE USE OF THE BIOELECTRICAL IMPEDANCE METHOD

    Directory of Open Access Journals (Sweden)

    Jendrysek Marek

    2015-11-01

    Full Text Available Purpose: Body composition evaluation of youth aged 17-18 of a different physical activity with the help of bioelectric impedance method. Material and Methods: 18 boys practicing swimming and 19 boys not practicing it took part in the study, making up a control group. Height, weight, BMI, lean body mass, the content of fat and water, Rohr factor were evaluated. Non-parametric Mann-Whitney test has been used to evaluate the differences in the range of the tissue components between the two groups. Results: Statistically significant differences were found on the p<0,05 level in % fat content. Mean body weight in experimental group was 71.5 kg, while in control group it was 69.4 kg. Minimum and maximum weight in group of swimming-practicing persons was: 56.6-92.2 kg. Increased body weight in the group of swimmers can result from greater amount of active tissue in this group compared with persons of low physical activity. Proportionally, it amounted to 64.3 kg and 61.3 kg. In the tested groups, minimal and maximal values of amount of active tissue proportionately amounted to: 54.1-78 and 49.5-72,3 kg. Conclusions: Physical activity modifies body composition. Active lifestyle is one of the methods for prevention of overweight and obesity.

  20. 多频多段人体生物电阻抗测量系统%A Bioelectrical Impedance Measurement System Based on Multi-Frequency and Multi-Segment Technology

    Institute of Scientific and Technical Information of China (English)

    高秀娥; 唐佳; 陈波

    2012-01-01

    Bioelectrical impedance is an important composition of human body, and reflects the physical conditions of human tissues to some extent. Based on this, a multi-frequency and multi-segment bioelectrical impedance measurement system is designed on the principle of eight electrodes. In fact, the system, which consists of MCU system, sinusoidal excitation current source, RMS-to-DC circuit and etc, has achieved the impedance measurement of the extremities as well as the trunk under the frequency ranged from 5 ~ 500 kHz. Experiment results show that the system finally realizes high-accuracy measurements of amplitude and phase of bioelectrical impedance with the result of a relative error of magnitude which is less than 0. 7% and an absolute error of phase which is less than 0.8°.%人体生物电阻抗是人体体成分的重要组成部分,在一定程度上反映了人体组织的生理状况.基于此,设计了一套基于八电极的多频多段人体生物电阻抗测量系统.测量系统由单片机系统、正弦交流激励电流源、有效值检测电路等组成,实现了5 ~ 500 kHz频率范围的左右上下肢及躯干的5段测量.测试结果表明,测量系统实现了人体生物电阻抗的幅值和相位的高精度测量,幅值相对误差小于0.7%,相位绝对误差小于0.8°.

  1. 生物电阻抗铜片电极的化学刻蚀工艺%Chemical etching process of copper electrode for bioelectrical impedance technology

    Institute of Scientific and Technical Information of China (English)

    周伟; 宋嵘; 蒋乐伦; 许文平; 梁国开; 程德才; 刘灵蛟

    2012-01-01

    为获得具有强稳定性能的生物电阻抗电极,采用化学刻蚀加工方法,制造出表面具有一系列微结构的金属铜片电极.通过改变加工工艺参数的方法,着重分析刻蚀时间、刻蚀温度、刻蚀液体浓度、样品尺寸等刻蚀工艺参数对铜片电极的蚀刻速率和表面微结构的影响.结果表明:刻蚀速率将随着刻蚀时间的延长而逐渐降低,随着刻蚀温度的升高而逐渐升高,而刻蚀样本尺寸对刻蚀速率的影响不大.选用合适的刻蚀液体浓度(组分3),在室温条件下刻蚀20 min,可以获得具有丰富表面微结构的铜片电极.另外,进行24 h电极对接的连续性交流阻抗测试,与心电电极相比,利用化学刻蚀加工的铜片电极,由于表面具有丰富的表面微结构,可以形成可靠的表面接触,从而具有稳定的交流阻抗值.%In order to obtain bioelectrical impedance electrodes with high stability,the chemical etching process was used to fabricate the copper electrode with a series of surface microstructures.By changing the etching processing parameters,some comparison experiments were performed to reveal the influence of etching time,etching temperature,etching liquid concentration,and sample sizes on the etching rate and surface microstructures of copper electrode.The result shows that the etching rate is decreased with increasing etching time,and is increased with increasing etching temperature.Moreover,it is found that the sample size has little influence on the etching rate.After choosing the reasonable etching liquid composition (formulation 3),the copper electrode with many surface microstructures can be obtained by chemical etching process at room temperature for 20 min.In addition,using the alternating current impedance test of electrode-electrode for 24 h,the copper electrode with a series of surface microstructures fabricated by the etching process presents a more stable impedance value compared with the

  2. Bioelectrical impedance is an accurate method to assess body composition in obese but not severely obese adolescents.

    Science.gov (United States)

    Verney, Julien; Metz, Lore; Chaplais, Elodie; Cardenoux, Charlotte; Pereira, Bruno; Thivel, David

    2016-07-01

    The aim of this study was to compare total and segmental body composition results between bioimpedance analysis (BIA) and dual x-ray absorptiometry (DXA) scan and to test the reproducibility of BIA in obese adolescents. We hypothesized that BIA offers an accurate and reproducible method to assess body composition in adolescents with obesity. Whole-body and segmental body compositions were assessed by BIA (Tanita MC-780) and DXA (Hologic) among 138 (110 girls and 28 boys) obese adolescents (Tanner stage 3-5) aged 14±1.5years. The BIA analysis was replicated on 3 identical occasions in 32 participants to test the reproducibility of the methods. Whole-body fat mass percentage was significantly higher using the BIA method compared with DXA (40.6±7.8 vs 38.8±4.9%, PBioimpedance analysis offers an acceptable and reproducible alternative to assess body composition in obese adolescents, with however a loss of correlation between BIA and DXA with increasing body fat; its validity remains uncertain for segmental analysis among obese youth. PMID:27333957

  3. DXA, bioelectrical impedance, ultrasonography and biometry for the estimation of fat and lean mass in cats during weight loss

    Directory of Open Access Journals (Sweden)

    Borges Naida C

    2012-07-01

    Full Text Available Abstract Background Few equations have been developed in veterinary medicine compared to human medicine to predict body composition. The present study was done to evaluate the influence of weight loss on biometry (BIO, bioimpedance analysis (BIA and ultrasonography (US in cats, proposing equations to estimate fat (FM and lean (LM body mass, as compared to dual energy x-ray absorptiometry (DXA as the referenced method. For this were used 16 gonadectomized obese cats (8 males and 8 females in a weight loss program. DXA, BIO, BIA and US were performed in the obese state (T0; obese animals, after 10% of weight loss (T1 and after 20% of weight loss (T2. Stepwise regression was used to analyze the relationship between the dependent variables (FM, LM determined by DXA and the independent variables obtained by BIO, BIA and US. The better models chosen were evaluated by a simple regression analysis and means predicted vs. determined by DXA were compared to verify the accuracy of the equations. Results The independent variables determined by BIO, BIA and US that best correlated (p r2, 19 equations were selected (12 for FM, 7 for LM; however, only 7 equations accurately predicted FM and one LM of cats. Conclusions The equations with two variables are better to use because they are effective and will be an alternative method to estimate body composition in the clinical routine. For estimated lean mass the equations using body weight associated with biometrics measures can be proposed. For estimated fat mass the equations using body weight associated with bioimpedance analysis can be proposed.

  4. 一种基于FPGA的数字EIT系统的实验研究%A Bioelectricity Impedance Measurement System Research Based on FPGA

    Institute of Scientific and Technical Information of China (English)

    孙晓彤; 郝会玲; 沙洪

    2013-01-01

    以FPGA芯片为核心的数字化生物电阻抗测量实验平台,主要完成直接数字频率合成(DDS)的电流源模块、V/I变换和数字解调模块的研究.采用DDS技术生成正弦信号发生器,由THS4021改进的Howland电路设计压控电流源,在不同负载条件下测量其输出电流幅值的频率响应,并在不同频率下测量电流源的输出阻抗,对恒流源性能的稳定性和精度进行测定.解调方法采用数字化解调,测试不同激励频率下的数字正交解调输出误差变化情况.最后采用盐水槽实验系统进行成像实验.结果表明,电流源可在6.1~390.6 kHz范围输出多频激励信号,在600 kHz前保持在190 kΩ的输出阻抗.当信号频率从200 kHz逐渐增加到1.6 MHz时,解调电路输出的I和Q路误差逐渐增加,对应的幅度误差从1.13%增加到7.19%,相位误差从1.03%增大到5.34%.采用相邻激励-相邻测量模式对环氧树脂棒进行盐水槽成像实验,成像结果表明系统能够对单个目标物体实现较准确的定位,验证了本研究平台的可行性.%In this work the digital bioelectricity impedance measurement experiment platform with the core of FPGA was studied and completed the research of the DDS module,V/I conversion and digital demodulation.DDS technology was used to generate a sinusoidal signal generator.Howland circuit improved by THS4021 was used to design a voltage-controlled current source,the amplitude of the output current of the frequency response was measured in different load conditions,and the output impedance of the current source was measured at different frequencies,which proved stability and accuracy of the constant current source.The digital demodulation was used in the study and tested digital quadrature demodulation output error under different excitation frequency.At last we used salt water tank experimental system for imaging experiments.The current source could produce multi-frequency excitation signal in

  5. Are ethnic and gender specific equations needed to derive fat free mass from bioelectrical impedance in children of South asian, black african-Caribbean and white European origin? Results of the assessment of body composition in children study.

    Directory of Open Access Journals (Sweden)

    Claire M Nightingale

    Full Text Available BACKGROUND: Bioelectrical impedance analysis (BIA is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500. Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z; B: FFM = linear combination(height(2/Z; C: FFM = linear combination(height(2/Z+weight}. RESULTS: Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A. The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A. Consistent results were observed when the equations were applied to a large external data set. CONCLUSIONS: Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations

  6. Wavelet analysis of the impedance cardiogram waveforms

    Science.gov (United States)

    Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.

    2012-12-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  7. Use of bioelectrical impedance analysis to assess body composition in rural Gambian children

    NARCIS (Netherlands)

    Prins, M.; Hawkesworth, S.; Wright, A.; Fulford, A.J.C.; Jarjou, L.M.A.; Prentice, A.M.; Moore, S.E.

    2008-01-01

    Objective: To validate the Tanita BC-418MA Segmental Body Composition Analyser and four-site skinfold measurements for the prediction of total body water (TBW), percentage fat-free mass (% FFM) and percentage body fat (%BF) in a population of rural Gambian children. Subjects/Methods: One hundred and

  8. Sensitivity field distributions for segmental bioelectrical impedance analysis based on real human anatomy

    International Nuclear Information System (INIS)

    In this work, an adaptive unstructured tetrahedral mesh generation technology is applied for simulation of segmental bioimpedance measurements using high-resolution whole-body model of the Visible Human Project man. Sensitivity field distributions for a conventional tetrapolar, as well as eight- and ten-electrode measurement configurations are obtained. Based on the ten-electrode configuration, we suggest an algorithm for monitoring changes in the upper lung area.

  9. Bioelectrical impedance analysis (BIA) for sarcopenic obesity (SO) diagnosis in young female subjects

    International Nuclear Information System (INIS)

    Sarcopenia is defined as a loss of muscle mass depending of ageing and affecting physical function (definition A). A new definition considers excluding mass reduction criterion (definition B). Obesity is pandemic and occurs at all ages. Sarcopenic obesity (SO) implies both processes. The purpose of this study was to compare the results obtained after applying these 2 definitions in 66 aged 22 ± 2.8 years overweight or obese young college women. Percentage body fat (%BF) and skeletal mass index (SMI) were estimated by BIA, muscle function by handgrip strength test (HGS) and physical performance by Harvard step test (HST). There were 9.1% and 90.9% overweight or obese subjects. Twenty nine subjects (43.9%) had decreased HGS and 22 (33.3%) had impaired physical performance. One obese subject (1.5%) met the criteria for sarcopenic obesity by definition A and 9 (13.6%) by definition B. Although a linear regression (α 2 = 0.094, 0.037 and 0.275 respectively) it was observed a tendency for HGS, HST and SMI deterioration when %BF increases. However, other confounding factors must be investigated. Probably as the population gets more obese, the problematic of SO will be found earlier in life.

  10. [ABDOMINAL BIOELECTRICAL IMPEDANCE ANALYSIS AND ANTHROPOMETRY FOR PREDICTING METABOLIC SYNDROME IN MIDDLE AGED MEN].

    Science.gov (United States)

    Fernández-Vázquez, Rosalía; Millán Romero, Ángel; Barbancho, Miguel Ángel; Alvero-Cruz, José Ramón

    2015-09-01

    Objetivo: la obesidad central tiene una gran relación con el síndrome metabólico. Estudiar la relación de la grasa del tronco, el índice de grasa visceral y las medidas antropométricas con el síndrome metabólico. Métodos: diseño: transversal descriptivo y correlacional. Participaron 75 varones, voluntarios, de distintas profesiones, que accedieron a un reconocimiento médico- laboral, con un rango de edad de 21 a 59 años. Mediciones de peso, talla, índice de masa corporal, perímetro abdominal, perímetro glúteo, índice cintura-cadera y grasa de tronco y nivel de grasa visceral mediante bioimpedanciometría (Tanita AB-140-ViScan) y parámetros bioquímicos: glucosa, colesterol total y triglicéridos. Así mismo, se midió la presión arterial sistólica y diastólica. Se comparan los estados de síndrome metabólico, sobrepeso y obesidad. Resultados: existen correlaciones de las medidas antropométricas con la de grasa de tronco y el nivel de grasa visceral, así como con los parámetros bioquímicos (p < 0,001). Un análisis de curvas ROC muestra que los puntos de corte a partir de los cuales se puede presentar el síndrome metabólico son de 32,7% de grasa de tronco y de 13 para el nivel de grasa visceral, con una alta sensibilidad y especificidad. Se obtienen los mismos puntos de corte para el estado de obesidad y síndrome metabólico. Conclusiones: la grasa de tronco y los niveles de grasa visceral son muy sensibles y específicos para la detección del síndrome metabólico y la obesidad, aunque no superan a las variables e índices antropométricos. En la condición de sobrepeso, la grasa de tronco y visceral son medidas algo más predictivas que las variables antropométricas.

  11. Bioelectrical impedance analysis (BIA): a proposal for standardization of the classical method in adults

    International Nuclear Information System (INIS)

    The accuracy of BIA measurements is limited by different sources of error such as physical model, cross sectional area, ethnicity, body hydration, age and level of body fat among other variables. Equation for each population is required as they can produce overestimation when manufacturer's equations are used. The classical measurements hand to foot has shown better correlation against hydrodensitometry than foot to foot or hand to hand. However there is a lack for an accepted standard of BIA procedures. This is compounded when there is not a good report of the BIA study's methodology; hence the comparability between the results is poor and reduces the reliability of the method. Perhaps, standardization of methods would be the first step for BIA studies to move forward and subsequently improve its accuracy. Standardized procedures could also minimize the impact of these variables on studies results. The aim of this study was to propose a protocol as a checklist to standardize BIA procedures and produce comparable results from future studies performed with the classic hand-foot configuration in adults.

  12. Sensitivity field distributions for segmental bioelectrical impedance analysis based on real human anatomy

    Science.gov (United States)

    Danilov, A. A.; Kramarenko, V. K.; Nikolaev, D. V.; Rudnev, S. G.; Salamatova, V. Yu; Smirnov, A. V.; Vassilevski, Yu V.

    2013-04-01

    In this work, an adaptive unstructured tetrahedral mesh generation technology is applied for simulation of segmental bioimpedance measurements using high-resolution whole-body model of the Visible Human Project man. Sensitivity field distributions for a conventional tetrapolar, as well as eight- and ten-electrode measurement configurations are obtained. Based on the ten-electrode configuration, we suggest an algorithm for monitoring changes in the upper lung area.

  13. The use of bioelectrical impedance analysis for body composition in epidemiological studies

    DEFF Research Database (Denmark)

    Böhm, A; Heitmann, B L

    2013-01-01

    with increased risk of developing chronic diseases. Studies, among others using BIA, suggest that low BMI may reflect low muscle and high BMI fat mass (FM). BIA-derived lean and FM is directly associated with morbidity and mortality. To the contrary, BMI is rather of limited use for measuring BF...

  14. Bioelectrical impedance analysis (BIA) for sarcopenic obesity (SO) diagnosis in young female subjects

    Science.gov (United States)

    González-Correa, C. H.; Caicedo-Eraso, J. C.; S, Villada-Gomez J.

    2013-04-01

    Sarcopenia is defined as a loss of muscle mass depending of ageing and affecting physical function (definition A). A new definition considers excluding mass reduction criterion (definition B). Obesity is pandemic and occurs at all ages. Sarcopenic obesity (SO) implies both processes. The purpose of this study was to compare the results obtained after applying these 2 definitions in 66 aged 22 ± 2.8 years overweight or obese young college women. Percentage body fat (%BF) and skeletal mass index (SMI) were estimated by BIA, muscle function by handgrip strength test (HGS) and physical performance by Harvard step test (HST). There were 9.1% and 90.9% overweight or obese subjects. Twenty nine subjects (43.9%) had decreased HGS and 22 (33.3%) had impaired physical performance. One obese subject (1.5%) met the criteria for sarcopenic obesity by definition A and 9 (13.6%) by definition B. Although a linear regression (α obese, the problematic of SO will be found earlier in life.

  15. Wave impedance retrieving via Bloch modes analysis

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, S.; Sukhorukov, A.;

    2011-01-01

    The main bottleneck in the restoration of electromagnetic effective parameters is connected to the impedance retrieving. The S-parameters method gives the input (Bloch) impedance, which, being then used for permittivity and permeability determination, causes some fundamental physics prin......-ciples violation, like antiresonance behaviour with Im(ε) fundamental) Bloch mode. Then it is possible to determine the Bloch and wave impedances by the surface and volume aver-aging of the electromagnetic field...

  16. Equivalent circuit models for ac impedance data analysis

    Science.gov (United States)

    Danford, M. D.

    1990-01-01

    A least-squares fitting routine has been developed for the analysis of ac impedance data. It has been determined that the checking of the derived equations for a particular circuit with a commercially available electronics circuit program is essential. As a result of the investigation described, three equivalent circuit models were selected for use in the analysis of ac impedance data.

  17. Modeling and Grid impedance Variation Analysis of Parallel Connected Grid Connected Inverter based on Impedance Based Harmonic Analysis

    DEFF Research Database (Denmark)

    Kwon, JunBum; Wang, Xiongfei; Bak, Claus Leth;

    2014-01-01

    This paper addresses the harmonic compensation error problem existing with parallel connected inverter in the same grid interface conditions by means of impedance-based analysis and modeling. Unlike the single grid connected inverter, it is found that multiple parallel connected inverters and grid...... impedance can make influence to each other if they each have a harmonic compensation function. The analysis method proposed in this paper is based on the relationship between the overall output impedance and input impedance of parallel connected inverter, where controller gain design method, which can...

  18. Equivalent Circuits For AC-Impedance Analysis Of Corrosion

    Science.gov (United States)

    Danford, M. D.

    1992-01-01

    Report presents investigation of equivalent circuits for ac-impedance analysis of corrosion. Impedance between specimen and electrolyte measured as function of frequency. Data used to characterize corrosion electrochemical system in terms of equivalent circuit. Eleven resistor/capacitor equivalent-circuit models were analyzed.

  19. Analysis and design of complex impedance transforming marchand baluns

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld M.

    2014-01-01

    A new type of Marchand balun is presented in this paper, which has the property of complex impedance transformation. To allow the Marchand balun to transform between arbitrary complex impedances, three reactances should be added to the circuit. A detailed analysis of the circuit gives the governing...

  20. Сhanges of brain bioelectric activity by diabetic encephalopathy

    OpenAIRE

    Vitaly P. Omelchenko; Elena A. Timoshenko

    2011-01-01

    This article focuses on the analysis of brain bioelectric activity by diabetic encephalopathy. Paid attention to the establishment of EEG parameters and patients psychological characteristics interrelation.

  1. Impedance analysis of fibroblastic cell layers measured by electric cell-substrate impedance sensing

    Science.gov (United States)

    Lo, Chun-Min; Ferrier, Jack

    1998-06-01

    Impedance measurements of cell layers cultured on gold electrode surfaces obtained by electric cell-substrate impedance sensing provide morphological information such as junctional resistance and cell-substrate separation. Previously, a model that assumes that cells have a disklike shape and that electric currents flow radially underneath the ventral cell surface and then through the paracellular space has been used to theoretically calculate the impedance of the cell-covered electrode. In this paper we propose an extended model of impedance analysis for cell layers where cellular shape is rectangular. This is especially appropriate for normal fibroblasts in culture. To verify the model, we analyze impedance data obtained from four different kinds of fibroblasts that display a long rectangular shape. In addition, we measure the average cell-substrate separation of human gingival fibroblasts at different temperatures. At temperatures of 37, 22, and 4 °C, the average separation between ventral cell surface and substratum are 46, 55, and 89 nm, respectively.

  2. Impedance analysis of an enhanced piezoelectric biosensor

    Science.gov (United States)

    Kim, Gi-Ho

    This study investigated the usefulness and characteristics of a five-megahertz quartz crystal resonator oscillating in a thickness-shear mode as a sensor of biological pathogens such as Salmonella typhimurium . An impedance analyzer measured the impedance of the oscillating quartz crystal, which determined all mechanical properties of the oscillating quartz and its immediate environment. In this study, the impedance behavior of the bare crystal was characterized in air and in potassium phosphate buffer solution. The potassium phosphate buffer was a Newtonian liquid. The resonance frequency of the oscillating quartz shifted down about 900 Hz by contacting with the buffer. An immobilized-antibody layer on the quartz surface behaved like a rigid mass when immersed in the buffer solution. The quartz crystal with immobilized antibodies was characterized in various solutions containing antibody- coated paramagnetic microspheres and varying concentrations of Salmonella typhimurium (102 - 108 cells/ml). The Salmonella cells were captured by antibody- coated paramagnetic microspheres, and then these complexes were moved magnetically to the oscillating quartz and were captured by antibodies immobilized on the crystal surface. The response of the crystal was expressed in terms of equivalent circuit parameters. The motional inductance and the motional resistance increased as a function of the concentration of Salmonella. The viscous damping was the main contribution to the resistance and the inductance in a liquid environment. The load resistance was the most effective and sensitive circuit parameter. A magnetic force was a useful method to collect the complexes of Salmonella-microspheres on the crystal surface and enhance the response sensor. In this system, the detection limit, based on resistance monitoring, was about 103 cells/ml.

  3. A comparative analysis of printing techniques by using an active concentric ring electrode for bioelectrical recording

    OpenAIRE

    García Breijo, Eduardo; Prats Boluda, Gema; Lidon-Roger, Jose V.; Ye Lin, Yiyao; Garcia Casado, Francisco Javier

    2015-01-01

    Purpose This paper aims to present a comparison between three types of manufacturing techniques, namely, screen-printed, inkjet and gravure, using different types of inks, for the implementation of concentric ring electrodes which permit estimation of Laplacian potential on the body surface. Design/methodology/approach Flexible concentric ring electrodes not only present lower skin electrode contact impedance and lower baseline wander than rigid electrodes but are also less sens...

  4. Change in fat-free mass assessed by bioelectrical impedance, total body potassium and dual energy X-ray absorptiometry during prolonged weight loss

    DEFF Research Database (Denmark)

    Hendel, H W; Gotfredsen, A; Højgaard, L;

    1996-01-01

    A total of 16 obese women (body mass index (BMI) 30-43 kg m(-2)) participated in a weight reduction study. Before and after a weight loss of 11.7 +/- 7.4 kg (mean +/- SD), body composition was assessed by dual energy X-ray absorptiometry (DXA), and total body potassium counting (TBK......). These measurements were compared with bioimpedance analysis (BIA) by applying 11 predictive BIA equations published in the literature. Predictive equations for the present study population were developed, with the use of fat-free mass (FFM) as assessed by TBK and DXA as references in multiple regression analysis...... equations are unable to predict static body composition and are not reproducible for individuals over time. However, a significant or insignificant change in R (without accompanying predictive equations) may be used to indicate whether FFM is lost or preserved in groups of obese subjects....

  5. Bioelectrical impedance for detecting and monitoring lymphedema in patients with breast cancer. Preliminary results of the florence nightingale breast study group.

    Science.gov (United States)

    Erdogan Iyigun, Zeynep; Selamoglu, Derya; Alco, Gul; Pilancı, Kezban Nur; Ordu, Cetin; Agacayak, Filiz; Elbüken, Filiz; Bozdogan, Atilla; Ilgun, Serkan; Guler Uysal, Fusun; Ozmen, Vahit

    2015-03-01

    The aim of this study was to evaluate the efficacy of bioimpedance spectroscopy for the follow-up of patients with lymphedema in Turkey and its benefits in the diagnosis of stage 0, 1, and 2 lymphedema in patients who are under treatment for breast cancer. Thirty-seven female patients with breast cancer who underwent surgical procedures in our Breast Health Centre were followed up for lymphedema using bioimpedance, and clinical measurements were taken for a minimum period of 1 year at 3-month intervals. Patients who had been monitored regularly between November, 2011, and September, 2013, were enrolled to the study. In total, 8 patients developed lymphedema with an overall rate of 21.6%. Among the 8 patients who developed lymphedema, 4 had Stage 2, 1 had Stage 1, and 3 had Stage 0 lymphedema. Stage 0 lymphedema could not be detected with clinical measurements. During the patients' 1-year follow-up period using measurements of bioimpedance, a statistically significant relationship was observed between the occurrence of lymphedema and the disease characteristics. including the number of the extracted and remaining lymph nodes and the region of radiotherapy (p=0.042, p=0.024, p=0.040). Bioimpedance analysis seems to be a practical and reliable method for the early diagnosis of lymphedema. It is believed that regular monitoring of patients in the high-risk group using bioimpedance analyses increases the ability to treat lymphedema.

  6. Uncertainty Analysis of the Grazing Flow Impedance Tube

    Science.gov (United States)

    Brown, Martha C.; Jones, Michael G.; Watson, Willie R.

    2012-01-01

    This paper outlines a methodology to identify the measurement uncertainty of NASA Langley s Grazing Flow Impedance Tube (GFIT) over its operating range, and to identify the parameters that most significantly contribute to the acoustic impedance prediction. Two acoustic liners are used for this study. The first is a single-layer, perforate-over-honeycomb liner that is nonlinear with respect to sound pressure level. The second consists of a wire-mesh facesheet and a honeycomb core, and is linear with respect to sound pressure level. These liners allow for evaluation of the effects of measurement uncertainty on impedances educed with linear and nonlinear liners. In general, the measurement uncertainty is observed to be larger for the nonlinear liners, with the largest uncertainty occurring near anti-resonance. A sensitivity analysis of the aerodynamic parameters (Mach number, static temperature, and static pressure) used in the impedance eduction process is also conducted using a Monte-Carlo approach. This sensitivity analysis demonstrates that the impedance eduction process is virtually insensitive to each of these parameters.

  7. Assessing Body Composition of Children and Adolescents Using Dual-Energy X-Ray Absorptiometry, Skinfolds, and Electrical Impedance

    Science.gov (United States)

    Mooney, Angela; Kelsey, Laurel; Fellingham, Gilbert W.; George, James D.; Hager, Ron L.; Myrer, J. William; Vehrs, Pat R.

    2011-01-01

    To determine the validity and reliability of percent body fat estimates in 177 boys and 154 girls between 12-17 years of age, percent body fat was assessed once using dual-energy X-ray absorptiometry and twice using the sum of two skinfolds and three bioelectrical impedance analysis devices. The assessments were repeated on 79 participants on a…

  8. Electrical Modeling and Impedance Analysis of Biological Cells

    Directory of Open Access Journals (Sweden)

    Gowri Sree V.

    2014-03-01

    Full Text Available It was proved that the external electric field intensity has significant effects on the biological systems. The applied electric field intensity changes the electrical behavior of the cell systems. The impact of electric field intensity on the cell systems should be studied properly to optimize the electric field treatments of biological systems. Based on the cell dimensions and its dielectric properties, an electrical equivalent circuit for an endosperm cell in rice was developed and its total impedance and capacitance were verified with measurement results. The variations of impedance and conductance with respect to applied impulse voltage at different frequencies were plotted. This impedance analysis method can be used to determine the optimum voltage level for electric field treatment and also to determine the cell rupture due to electric field applications.

  9. Fiber Materials AC Impedance Characteristics and Principium Analysis

    Science.gov (United States)

    Wang, Jianjun; Li, Xiaofeng

    With an invariable amplitude and variable frequency inspiriting, impedance of fiber materials rapidly decrease at first and then increase speedy followed with increasing of signal frequency. For the impedance curve of frequency is section of bathtub, this phenomenon is defined as alternating current electric conductive bathtub effect of fiber material. With analysis tools,of circuit theory and medium polarization theory, the phenomenon can be deeply detected that in AC electric field there are four different kind of currents in fiber material: absorbing current, conductance current, charging current and superficial current. With more analyzing it's discovered this phenomenon can be explained by medium polarize theory. Make using of fiber AC electric conductivity bathtub effect, fast testing equipment on fiber moisture regain can be invent, and disadvantages of conventional impedance technique, such as greatness test error and electrode polarization easily. This paper affords directions to design novel speediness fiber moisture test equipments in theory.

  10. A parametric framework for modelling of bioelectrical signals

    CERN Document Server

    Mughal, Yar Muhammad

    2016-01-01

    This book examines non-invasive, electrical-based methods for disease diagnosis and assessment of heart function. In particular, a formalized signal model is proposed since this offers several advantages over methods that rely on measured data alone. By using a formalized representation, the parameters of the signal model can be easily manipulated and/or modified, thus providing mechanisms that allow researchers to reproduce and control such signals. In addition, having such a formalized signal model makes it possible to develop computer tools that can be used for manipulating and understanding how signal changes result from various heart conditions, as well as for generating input signals for experimenting with and evaluating the performance of e.g. signal extraction methods. The work focuses on bioelectrical information, particularly electrical bio-impedance (EBI). Once the EBI has been measured, the corresponding signals have to be modelled for analysis. This requires a structured approach in order to move...

  11. A Planar Interdigital Sensor for Bio-impedance Measurement: Theoretical analysis, Optimization and Simulation

    Directory of Open Access Journals (Sweden)

    Thanh-Tuan Ngo

    2014-04-01

    Full Text Available This paper proposes the design of a biosensor to characterize the dielectric and conductive properties of biological materials (for example blood or water by impedance spectroscopy. Particularly, its design optimized the geometric structure interdigitated electrodes. This optimization allows extending the frequency range of measurement by reducing the polarization effect. Polarization effect is manifested by an interface capability (or double layer from interaction between ions and molecules in the boundary between the surface of the electrolyte and the electrodes, it increases the measurement error at low frequencies. This paper recommends also a novel method to determine the parameters (relative permittivity, thickness and capacitance per unit area of the double layer (DL at the contact surface of the electrode with the solution. CoventorWare software was utilized to modelize of interdigital sensor structure in three dimensions (3D to verify the analytical results and evaluate the influence of geometrical parameters and the dielectric properties of the medium on bioelectrical impedance.

  12. Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes

    KAUST Repository

    Ruffo, Riccardo

    2009-07-02

    The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a lithium ion battery. The ac response was measured by using impedance spectroscopy in equilibrium conditions at different lithium compositions and during several cycles of charge and discharge in a half cell vs. metallic lithium. The impedance analysis shows the contribution of both surface resistance and solid state diffusion through the bulk of the nanowires. The surface process is dominated by a solid electrolyte layer (SEI) consisting of an inner, inorganic insoluble part and several organic compounds at the outer interface, as seen by XPS analysis. The surface resistivity, which seems to be correlated with the Coulombic efficiency of the electrode, grows at very high lithium contents due to an increase in the inorganic SEI thickness. We estimate the diffusion coefficient of about 2 × 10 -10 cm 2/s for lithium diffusion in silicon. A large increase in the electrode impedance was observed at very low lithium compositions, probably due to a different mechanism for lithium diffusion inside the wires. Restricting the discharge voltage to 0.7 V prevents this large impedance and improves the electrode lifetime. Cells cycled between 0.07 and 0.70 V vs. metallic lithium at a current density of 0.84 A/g (C/5) showed good Coulombic efficiency (about 99%) and maintained a capacity of about 2000 mAh/g after 80 cycles. © 2009 American Chemical Society.

  13. Analysis of impedance measurements of a suspension of microcapsules using a variable length impedance measurement cell

    Directory of Open Access Journals (Sweden)

    Dejan Krizaj

    2012-10-01

    Full Text Available Electrical impedance measurements of the suspensions have to take into account the double layer impedance that is due to a very thin charged layer formed at the electrode-electrolite interface. A dedicated measuring cell that enables variation of the distance between the electrodes was developed for investigation of electrical properties of suspensions using two electrode impedance measurements. By varying the distance between the electrodes it is possible to separate the double layer and the suspension impedance from the measured data. From measured and extracted impedances electrical lumped models have been developed. The error of non inclusion of the double layer impedance has been analyzed. The error depends on the frequency of the measurements as well as on the distance between the electrodes.

  14. Analysis of formulas used in coupling impedance coaxial-wire measurements for distributed impedances

    International Nuclear Information System (INIS)

    In this paper the authors study the validity of coupling impedance bench measurements for distributed impedances, comparing the commonly used log formula to the result obtained applying a modified version of Bethe's theory of diffraction to a long slot in a coaxial beam pipe. The equations found provide a quantitative expression for the influence of the wire thickness used in the measurement of the real and imaginary part of the longitudinal impedance. The precision achievable in an actual measurement is therefore discussed. The method presented has also been applied in the presence of lumped impedances

  15. AC Complex Impedance Analysis of Doped Strontium Titanate Multifunctional Ceramics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Doped SrTiO3 capacitor-varistor multifunctional ceramics were fabricated by a single sintering process. AC compleximpedance analysis was performed to investigate electrical features ofgrains and grain boundaries for both as-reducedceramic and reoxidized ceramics. The results showed that the as-reduced ceramic exhibited inductive response athigh frequencies above 2 MHz, which is attributed to the contribution of electron behavior in semiconducting grains.The high frequency inductive response disappeared in impedance plots of reoxidized ceramics.

  16. Bioelectrical Perchlorate Remediation

    Science.gov (United States)

    Thrash, C.; Achenbach, L. A.; Coates, J. D.

    2007-12-01

    Several bioreactor designs are currently available for the ex-situ biological attenuation of perchlorate- contaminated waters and recently, some of these reactor designs were conditionally approved by the California Department of Health Services for application in the treatment of perchlorate contaminated drinking water. However, all of these systems are dependent on the continual addition of a chemical electron donor to sustain microbial activity and are always subject to biofouling and downstream water quality issues. In addition, residual labile electron donor in the reactor effluent can stimulate microbial growth in water distribution systems and contribute to the formation of potentially toxic trihalomethanes during disinfection by chlorination. As part of our ongoing studies into microbial perchlorate reduction we investigated the ability of dissimilatory perchlorate reducing bacteria (DPRB) to metabolize perchlorate using a negatively charged electrode (cathode) in the working chamber of a bioelectrical reactor (BER) as the primary electron donor. In this instance the DPRB use the electrons on the electrode surface either directly or indirectly in the form of electrolytically produced H2 as a source of reducing equivalents for nitrate and perchlorate reduction. As part of this investigation our fed-batch studies showed that DPRB could use electrons from a graphite cathode poised at -500mV (vs. Ag/AgCl) for the reduction of perchlorate and nitrate. We isolated a novel organism, Dechlorospirillum strain VDY, from the cathode surface after 70 days operation which readily reduced 100 mg.L-1 perchlorate in a mediatorless batch bioelectrical reactor (BER) in 6 days. Continuous up-flow BERs (UFBERs) seeded with active cultures of strain VDY continuously treated waters containing 100 mg.L-1 perchlorate with almost 100% efficiency throughout their operation achieving a non-optimized volumetric loading of 60 mg.L-1 reactor volume.day-1. The same UFBERs also treated

  17. Сhanges of brain bioelectric activity by diabetic encephalopathy

    Directory of Open Access Journals (Sweden)

    Vitaly P. Omelchenko

    2011-05-01

    Full Text Available This article focuses on the analysis of brain bioelectric activity by diabetic encephalopathy. Paid attention to the establishment of EEG parameters and patients psychological characteristics interrelation.

  18. Electrochemical impedance analysis of SOFC cathode reaction using evolutionary programming

    Energy Technology Data Exchange (ETDEWEB)

    Hershkovitz, S.; Baltianski, S.; Tsur, Y. [Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa (Israel)

    2012-02-15

    Investigation of the cathode reaction in solid oxide fuel cells (SOFC) by impedance spectroscopy (IS) measurements using evolutionary-based programming analysis is demonstrated. In contrast to the conventional analysis methods used for impedance spectroscopy measurements, e.g., equivalent circuits, the impedance spectroscopy genetic programming (ISGP) program seeks for a distribution of relaxation times that has the form of a peak or a sum of several peaks, assuming the Debye kernel. Using this method one finds a functional (parametric) form of the distribution of relaxation times. A symmetric cell configuration of Pt vertical stroke LSCF vertical stroke GDC vertical stroke LSCF vertical stroke Pt was examined using IS measurements combined with I-V measurements. Different samples at different temperatures and different oxygen partial pressures were examined in order to investigate their influence on the oxygen reduction reaction. The resulting IS data was analyzed using the ISGP program and the resulting peaks constructing the distribution of relaxation times were assigned for the different processes that occur at the cathode side. The activation energies as well as the dependence of the processes on the oxygen partial pressure were also evaluated. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Quantitative analysis of bioelectrical potentials for the diagnosis of internal organ pathology and theoretical speculations concerning electrical circulation in the organism.

    Science.gov (United States)

    Zukauskas, G; Dapsys, K; Ilgesviciute, J; Vaitkus, P

    1988-01-01

    Over 900 experiments on dogs and 135 clinical investigations of healthy people and patients of psychiatric and cardiological departments were performed. With the aid of a 8-channel biopotential amplifier and integrator, bioelectrical potential (BEP) directly from internal organs or from various skin zones were recorded. The quantitative parameters of the BEP--their square values and the sum of the square values of BEP recorded simultaneously from several points of the organism--were measured. The effect of low (1 Hz) and high (28 GHz) frequency electrical stimulation was studied. The stimulation of spleen, liver, stomach, small intestine and corresponding acupuncture points had the greatest effect on the quantitative parameters of the BEP in stomach and small intestine. During patient investigation, the most remarkable changes of the studied parameters were noticed in the BEP recorded from the acupuncture points of the affected internal organ meridians. The existence of the common points between Eastern medicine and Western science are discussed. The analysis of the BEP quantitative parameters proves the existence of electrophysiological equilibrium parameters in the organism--bioelectrical homeostasis. The possible theories of electrical circulation in the organism and their relations with traditional acupuncture theoretical concepts are also discussed. PMID:2904209

  20. Bioelectric signal classification using a recurrent probabilistic neural network with time-series discriminant component analysis.

    Science.gov (United States)

    Hayashi, Hideaki; Shima, Keisuke; Shibanoki, Taro; Kurita, Yuichi; Tsuji, Toshio

    2013-01-01

    This paper outlines a probabilistic neural network developed on the basis of time-series discriminant component analysis (TSDCA) that can be used to classify high-dimensional time-series patterns. TSDCA involves the compression of high-dimensional time series into a lower-dimensional space using a set of orthogonal transformations and the calculation of posterior probabilities based on a continuous-density hidden Markov model that incorporates a Gaussian mixture model expressed in the reduced-dimensional space. The analysis can be incorporated into a neural network so that parameters can be obtained appropriately as network coefficients according to backpropagation-through-time-based training algorithm. The network is considered to enable high-accuracy classification of high-dimensional time-series patterns and to reduce the computation time taken for network training. In the experiments conducted during the study, the validity of the proposed network was demonstrated for EEG signals.

  1. Design and Analysis of Impedance Pumps Utilizing Electromagnetic Actuation

    Directory of Open Access Journals (Sweden)

    Yu-Hisang Wang

    2010-04-01

    Full Text Available This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS diaphragm. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnetic diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impedance mismatch within the microchannel, which results in a net flow. In performing the analysis, simulated models of the magnetic field, the diaphragm displacement and the flow rate are developed using Ansoft/Maxwell3D, ANSYS FEA and FLUENT 6.3 CFD software, respectively. Overall, the simulated results reveal that a net flow rate of 52.8 μL/min can be obtained using a diaphragm displacement of 31.5 μm induced by a micro-coil input current of 0.5 A. The impedance pump proposed in this study provides a valuable contribution to the ongoing development of Lab-on-Chips (LoCs systems.

  2. Interobserver and Intraobserver Variability in pH-Impedance Analysis between 10 Experts and Automated Analysis

    DEFF Research Database (Denmark)

    Loots, Clara M; van Wijk, Michiel P; Blondeau, Kathleen;

    2011-01-01

    OBJECTIVE: To determine interobserver and intraobserver variability in pH-impedance interpretation between experts and accuracy of automated analysis (AA). STUDY DESIGN: Ten pediatric 24-hour pH-impedance tracings were analyzed by 10 observers from 7 world groups and with AA. Detection of gastroe......OBJECTIVE: To determine interobserver and intraobserver variability in pH-impedance interpretation between experts and accuracy of automated analysis (AA). STUDY DESIGN: Ten pediatric 24-hour pH-impedance tracings were analyzed by 10 observers from 7 world groups and with AA. Detection....... CONCLUSION: Interobserver agreement in combined pH-multichannel intraluminal impedance analysis in experts is moderate; only 42% of GER episodes were detected by the majority of observers. Detection of total GER numbers is more consistent. Considering these poor outcomes, AA seems favorable compared...

  3. Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    For the cascaded converter system, the output impedance of source converter interacts with the input impedance of load converter, and the interaction may cause the system instability. In bidirectional applications, when the power flow is reversed, the impedance interaction also varies, which brin...

  4. Digital surgery: Bioelectrical impedance measurement assistance on clinical operation%数字化外科:生物电阻抗测量技术辅助临床外科的操作

    Institute of Scientific and Technical Information of China (English)

    王智运; 尹庆水

    2011-01-01

    背景:现代临床外科操作对减少创伤和提高精确度的要求日益提高,生物电阻抗测量技术能将人体组织的信息转化为数字化信号,识别不同组织、器官,进而达到辅助临床操作的目的.目的:回顾分析生物电阻抗测量技术通过数字化转换辅助临床诊断、治疗以及手术等操作过程的情况.方法:由第一作者检索 1999/2009 PubMed数据及万方数据库有关使用生物电阻抗测量技术辅助临床诊断、治疗以及手术等操作,通过数字化信号的采集和分析达到实时定位、定性、提高精度和疗效评估等方面的文献.结果与结论:生物电阻抗测量技术以其无创、安全、可持续监控、多次测量和重复使用等优点,是一种理想的临床操作辅助手段.随着该技术新理论、新方法的不断发展,许多学者在此基础上对其辅助临床操作的应用进行了大量的研究和尝试,有理由相信其辅助应用的范围也将进一步扩大.%BACKGROUND: Modern chirurgery technique claims less trauma and higher precision. Bioelectical impedance measurement technique, which transfers anthropometric tissue information to digital signal, can afford aid to clinical surgery discriminate different tissue and organ.OBJECTIVE: To summarize the clinical application of bioelectical impedance measurement technique for assistance of the chirurgery operation.METHODS: Literatures about application of bioelectical impedance measu rement technique for the chirurgery operation were searched from Chinese Journal Full-text database and PubMed database, published from 1999 to 2009. Articles that qualitatively improve accuracy and curative effect evaluation using digital signal collection and analysis were analyzed.RESULTS AND CONCLUSION: The bioelectical impedance measurement technique is an ideal aided means, by the advantages of noninvasive, safe, durative monitoring, and repetitive use. With developing theory and methods of this

  5. Grado de acuerdo entre los índices adiposo-musculares obtenidos a partir de medidas antropométricas del brazo, pliegues cutáneos e impedancia bioeléctrica Interchangeability of the fat-to-fat-free mass ratios obtained by arm anthropometric measures, skinfold thickness and bioelectrical impedance

    Directory of Open Access Journals (Sweden)

    V. Martín Moreno

    2003-04-01

    agreement among the fat-to-fat-free mass ratios obtained by arm anthropometric measures (fat-muscle index, FMI, Siri equation for the sum of four skinfold thickness (body fat-muscle index, BFMI Siri and triceps skinfold (BFMItriceps and bioelectrical impedance (BFMI Omron methods. Methods: This is a cross-sectional study. A total of 145 patients were evaluated by anthropometry and bioelectrical impedance (Omron BF 300(, being estimated the agreement through the Intraclass Correlation Coefficient (ICC and Bland-Altman method. The reference method was BFMI Siri. Results: The ICC between BFMI Siri - BFMItriceps were 0,9304 (0,9035; 0,9498, between BFMI Siri - FMI of 0,7726 (0,6846; 0,8361 and between BFMI Siri - BFMI Omron of 0,9114 (0,8771; 0,9361. BFMItriceps (limits of agreement -0,171 to 0,117 show the best agreement according to Bland-Altman analysis with BFMI Siri, followed by BMFI Siri - BFMI Omron (-0,186; 0,178. The agreement limits between FMI and BFMI Siri (-0,2; 0,42, BFMItriceps (-0,26; 0,42 or BFMI Omron (-0,292; 0,504 were beyond of the established cut-off points (-0,2; 0,2. Conclusions: Due to the nature of the statistical agreement BFMItriceps and BFMI Omron are methods interchangeable methods between them and with BFMI Siri. FMI is not interchangeable with BFMI Siri, BFMI Omron or BFMItriceps. These results suggest that FMI cannot estimate properly the body composition. BFMItriceps and BFMI Omron are valid alternative methods to be used instead BFMI Siri in the fat-to-fat-free mass ratio assessment.

  6. 多频生物电阻抗技术评价 COPD 患者营养状况及其与血气分析指标的相关性%Evaluation of Nutritional Status in COPD Patients by Multi - frequency Bioelectrical Impedance and Its Correlation With Blood Gas Indicators

    Institute of Scientific and Technical Information of China (English)

    黄陈; 朱文艺; 徐静; 李利; 樊荣; 李琦; 王建

    2015-01-01

    Objective To examine the body composition of COPD patients by multi - frequency bioelectrical impedance and investigate the relationship between body composition and blood gas indicators in order to provide clinical references for nutritional support for COPD patients. Methods We enrolled 62 patients who was hospitalized and diagnosed with COPD in the Department of Respiratory Medicine of Xinqiao Hospital from January to June in 2011. Multi - frequency bioelectrical impedance was used to detect the patients' physical composition. We collected data of serum total protein,albumin, prealbumin,hemoglobin,lymph cell count,blood gas( PaCO2 ,PaO2 and SpO2 ),HCO -3 ,Cl - ,K + ,Na + ,pH of the subjects at admission. Statistical analysis was conducted on the above indicators. Results The malnutrition rates assessed by ribosomal protein content,body fat content,BMI and MAC were 41. 9% ,17. 7% ,19. 4% and 16. 1% , respectively. According the BMI,the patients with inadequate,normal and excess nutrition were significantly different( P < 0. 05 )in ribosomal TBW,BFM,PBF,FFM,PBFF,protein content and PBP;the subjects with inadequate nutrition were higher(P <0. 05)than those with normal and high nutrition in PBP;the subjects with inadequate nutrition were lower( P < 0. 05)than those with normal and high nutrition in PBF and FFM. TBW,FFM,ribosomal protein,and SMM were negatively correlated with PaO2 ( r = - 0. 311, - 0. 306, - 0. 308, - 0. 306;P < 0. 05),and BMI was negatively correlated with SpO2 ( r =- 0. 304,P < 0. 05). Conclusion COPD patients have high malnutrition rate when assessed by ribosomal protein. FFM is more sensitive than BMI in nutritional evaluation of COPD patients. The increase of FFM in COPD patients may improve hypoxia tolerance.%目的:应用多频生物电阻抗技术分析 COPD 患者人体成分及其与血气分析指标的关系,为 COPD 患者的营养支持提供依据。方法选择2011年1—6月在新桥医院呼吸科住院并诊断为 COPD

  7. Handling uncertainty in bioenergy policy design – A case study analysis of UK and German bioelectricity policy instruments

    International Nuclear Information System (INIS)

    In designing policies to promote bioenergy, policy makers face challenges concerning uncertainties about the sustainability of bioenergy pathways (including greenhouse gas balances), technology and resource costs, or future energy market framework conditions. New information becomes available with time, but policy adjustments can involve high levels of adaptation costs. To enable an effective steering of technology choices and innovation, policies have to strike a balance between creating a consistent institutional framework, which establishes planning security for investors, and sufficient flexibility to adapt to new information. This paper examines implications of economic theory for handling cost and benefit uncertainty in bioelectricity policy design, focussing on choices between price and quantity instruments, technology differentiation, and policy adjustment. Findings are applied to two case studies, the UK's Renewables Obligation and the German feed-in tariff/feed-in premium scheme. Case study results show the trade-offs that are involved in instrument choice and design – depending on political priorities and a country's specific context, different options can prove more adequate. Combining market-based remuneration with sustainability criteria results in strong incentives for bioenergy producers to search for low-cost solutions; whereas cost-based price instruments with centrally steered technology and feedstock choices offer higher planning security for investors and more direct control for policy makers over what pathways are implemented. Independent of the choice of instrument type and technology differentiation mechanism, findings emphasise the importance of a careful policy design, which determines the exact balance between performance criteria such as cost control, incentive intensity, planning security and adaptive efficiency. - Highlights: • Bioelectricity policy design must deal with simultaneous cost and benefit uncertainty.

  8. Harmonic analysis for identification of nonlinearities in impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kiel, M.; Bohlen, O.; Sauer, D.U. [Electrochemical Energy Conversion and Storage Systems Group, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University (Germany)

    2008-10-30

    Though impedance is only defined for linear systems, impedance spectroscopy is also successfully applied to nonlinear systems such as fuel cells and batteries. The influence of nonlinearities on measurement results in impedance spectroscopy is therefore discussed on a theoretical and simulative basis. The basis is a simplified Randles model of an electrochemical cell, on which a simulated impedance spectroscopy in galvanostatic mode is performed. For the investigation the focus is on the Butler-Vollmer equation in order to describe the nonlinearity. Furthermore, a linear model for comparison is used, in which the Butler-Volmer nonlinearity is replaced by a linear resistor to show the differences in impedance measurement. In order to find a correlation, also the occurring harmonics are observed. The results are discussed and several methods are suggested for maintaining a quasi-linear impedance measurement by controlling the amplitude of the excitation signal. (author)

  9. Transformerless High-Quality Electrocardiogram and Body Impedance Recording by an Amplifier with Current-Driven Inputs

    Directory of Open Access Journals (Sweden)

    Dobrev D.

    2009-12-01

    Full Text Available Measurement and recording of changes in bioelectrical impedance in vivo has become a widely used method with various clinical applications. It includes basal impedance Zo, relative changes ΔZ or its derivative dZ. Many applications related to cardiac and respiratory function require simultaneous electrocardiogram, impedance cardiogram and/or respiration signals recording and analysis. Accurate recording of body impedance is limited by high common mode voltages at the amplifier inputs combined with the influence of the output impedance of the used current source. A circuit concept for a simultaneous high-quality electrocardiogram and bioimpedance acquisition is proposed, profiting from advantages offered by a previously specially designed amplifier with current-driven inputs, yielding to low common mode and high differential mode input impedances.

  10. Extensions to a manifold learning framework for time-series analysis on dynamic manifolds in bioelectric signals

    Science.gov (United States)

    Erem, Burak; Martinez Orellana, Ramon; Hyde, Damon E.; Peters, Jurriaan M.; Duffy, Frank H.; Stovicek, Petr; Warfield, Simon K.; MacLeod, Rob S.; Tadmor, Gilead; Brooks, Dana H.

    2016-04-01

    This paper addresses the challenge of extracting meaningful information from measured bioelectric signals generated by complex, large scale physiological systems such as the brain or the heart. We focus on a combination of the well-known Laplacian eigenmaps machine learning approach with dynamical systems ideas to analyze emergent dynamic behaviors. The method reconstructs the abstract dynamical system phase-space geometry of the embedded measurements and tracks changes in physiological conditions or activities through changes in that geometry. It is geared to extract information from the joint behavior of time traces obtained from large sensor arrays, such as those used in multiple-electrode ECG and EEG, and explore the geometrical structure of the low dimensional embedding of moving time windows of those joint snapshots. Our main contribution is a method for mapping vectors from the phase space to the data domain. We present cases to evaluate the methods, including a synthetic example using the chaotic Lorenz system, several sets of cardiac measurements from both canine and human hearts, and measurements from a human brain.

  11. Extensions to a manifold learning framework for time-series analysis on dynamic manifolds in bioelectric signals.

    Science.gov (United States)

    Erem, Burak; Martinez Orellana, Ramon; Hyde, Damon E; Peters, Jurriaan M; Duffy, Frank H; Stovicek, Petr; Warfield, Simon K; MacLeod, Rob S; Tadmor, Gilead; Brooks, Dana H

    2016-04-01

    This paper addresses the challenge of extracting meaningful information from measured bioelectric signals generated by complex, large scale physiological systems such as the brain or the heart. We focus on a combination of the well-known Laplacian eigenmaps machine learning approach with dynamical systems ideas to analyze emergent dynamic behaviors. The method reconstructs the abstract dynamical system phase-space geometry of the embedded measurements and tracks changes in physiological conditions or activities through changes in that geometry. It is geared to extract information from the joint behavior of time traces obtained from large sensor arrays, such as those used in multiple-electrode ECG and EEG, and explore the geometrical structure of the low dimensional embedding of moving time windows of those joint snapshots. Our main contribution is a method for mapping vectors from the phase space to the data domain. We present cases to evaluate the methods, including a synthetic example using the chaotic Lorenz system, several sets of cardiac measurements from both canine and human hearts, and measurements from a human brain. PMID:27176304

  12. Comparison of bioelectrical impedance with skinfold thickness and X-ray absorptiometry to measure body composition in HIV-infected with lipodistrophy Comparación de impendancia bioeléctrica con grosor de pliegues cutáneos y absorciometría de rayos X para mensurar la composición corporal de personas con VIH con lipodistrofia

    Directory of Open Access Journals (Sweden)

    H. Siqueira Vassimon

    2011-06-01

    Full Text Available Introduction: Human immunodeficiency vírus (HIV-associated lipodystrophy syndrome (LS includes body composition and metabolic alterations. Lack of validated criteria and tools make difficult to evaluate body composition in this group. Objective: The aim of the study was to compare different methods to evaluate body composition between Brazilians HIV subjects with (HIV+LIPO+ or without LS (HIV+LIPO- and healthy subjects (Control. Methods: in a cross-sectional analyses, body composition was measured by bioelectrical impedance analysis (BIA, skinfold thickness (SF and dual-energy x-ray absorptiometry (DXA in 10 subjects from HIV+LIPO+ group; 22 subjects from HIV+LIPO- group and 12 from Control group. Results: There were no differences in age and body mass index (BMI between groups. The fat mass (FM (% estimated by SF did not correlate with DXA in HIV+LIPO+ group (r = 0,46/ p > 0,05 and had fair agreement in both HIV groups (HIV+LIPO+ =0,35/ HIV+ LIPO- = 0,40. BIA had significant correlation in all groups (p Introducción: El síndrome de lipodistrofia (SL asociado al virus de inmunodeficiencia humana (HIV incluye alteraciones en la composición corporal y metabólica. La falta de herramientas adecuadas y criterios válidos dificultan la evaluación de la composición corporal en este grupo. Objetivo: El objetivo del estudio fue comparar distintos métodos para evaluar la composición corporal entre individuos brasileños con HIV que teniam (HIV+LIPO+ o no LS (HIV+LIPO- e individuos sanos (control. Métodos: Estudio transversal en el que fue evaluada la composición corporal por análisis de impedancia bioeléctrica (BIA, pliegues cutáneos (SF y absorciometría de rayos X de doble energía (DXA en un grupo de 10 individuos con HIV+LIPO+, 22 individuos del grupo HIV+ LIPO- y 12 individuos del grupo control. Resultados: No hubo diferencias en la edad e índice de masa corporal (IMC entre grupos. La masa grasa (MG (% estimada por SF no se correlacion

  13. INFLUÊNCIA DE DIFERENTES TIPOS DE ELETRODOS SOBRE OS VALORES DA BIOIMPEDÂNCIA CORPORAL E NA ESTIMATIVA DE MASSA MAGRA (MM EM GATOS ADULTOS INFLUENCE OF DIFFERENT TYPES OF ELECTRODES ON THE BIOELECTRICAL IMPEDANCE VALUES AND IN THE ESTIMATION OF LEAN BODY MASS (LBM IN ADULT CATS

    Directory of Open Access Journals (Sweden)

    Thassila Caccia Feragi Cintra

    2010-04-01

    Full Text Available A bioimpedância (BIC é um método que aplica à tecnologia da impedância no estudo da composição corporal pela avaliação da diferença da condutividade elétrica dos tecidos. Os resultados da BIC são expressos pelas medidas primárias de resistência (R e reatância (Xc. Neste experimento, o método foi desenvolvido para verificar a viabilidade do uso de três diferentes tipos de eletrodos sobre a reprodutibilidade dos valores de R e Xc em gatos adultos. As médias de R e Xc com adesivos e agulhas de acupuntura não diferiram entre si (p?0,05, e os menores valores dos coeficientes de variação obtidos com estes eletrodos sinalizaram para uma melhor reprodutibilidade dos resultados quando comparados com os da agulha hipodérmica. Os diferentes tipos de eletrodos não interferiram nos valores da massa magra (MM estimada por equação específica, porém a agulha de acupuntura mostrou ser o eletrodo mais estável e de melhor aplicabilidade. A MM determinada com os diferentes tipos de eletrodos foi superior (p?0,05 à obtida com a absorciometria de raios-x de dupla energia (DEXA, provavelmente decorrente da equação utilizada na sua estimativa.

    PALAVRAS-CHAVES: Composição corporal, felinos, impedância, massa magra.
    The bioelectrical impedance is a method that applies impedance technology in the study of physical composition by evaluation of electrical conductivity difference on each organism tissue. The results of bioelectrical impedance (BIC are expressed by the resistance (R and reactance (Xc primary measures. This study was carried out to verify the viability of the use of three different electrodes on the repeatability of R and Xc values in adult cats. The averages of R and Xc estimated by adhesive and acupuncture needles did not differ from each other (p?0.05 and the smaller values of the variation coefficient acquired with these electrodes signaled for a better reproducibility of the results when compared with

  14. Analysis of impedance characteristics of IMPATT-generators

    Directory of Open Access Journals (Sweden)

    F. B. Bereziuk

    2007-10-01

    Full Text Available Model of power solid-state oscillators in a millimeter wave band is presented. This model based on non-stationary impedance characteristics of pulse oscillating impact avalanche transit time diodes.

  15. Impedance Analysis of Longitudinal Bunch Shape Measurements at PLS

    CERN Document Server

    Hwang, Ilmoon; Kim Eun San; Yoon, Moohyun

    2005-01-01

    We measured the longitudinal bunch shape by streak camera at 2.5 GeV Pohang Light Source. The impedances estimated by a series R+L model indicate a resistance R= 960 ohm, an inductance L= 80 nH and a longitudinal impedance Z/n= 0.53 ohm. The scaling law for the bunch lengthenig is expressed as I0

  16. Two port network analysis for three impedance based oscillators

    KAUST Repository

    Said, Lobna A.

    2011-12-01

    Two-port network representations are applied to analyze complex networks which can be dissolved into sub-networks connected in series, parallel or cascade. In this paper, the concept of two-port network has been studied for oscillators. Three impedance oscillator based on two port concept has been analyzed using different impedance structures. The effect of each structure on the oscillation condition and the frequency of oscillation have been introduced. Two different implementations using MOS and BJT have been introduced. © 2011 IEEE.

  17. Impedance analysis of porous carbon electrodes to predict rate capability of electric double-layer capacitors

    Science.gov (United States)

    Yoo, Hyun Deog; Jang, Jong Hyun; Ryu, Ji Heon; Park, Yuwon; Oh, Seung M.

    2014-12-01

    Electrochemical impedance analysis is performed to predict the rate capability of two commercial activated carbon electrodes (RP20 and MSP20) for electric double-layer capacitor. To this end, ac impedance data are fitted with an equivalent circuit that comprises ohmic resistance and impedance of intra-particle pores. To characterize the latter, ionic accessibility into intra-particle pores is profiled by using the fitted impedance parameters, and the profiles are transformed into utilizable capacitance plots as a function of charge-discharge rate. The rate capability that is predicted from the impedance analysis is well-matched with that observed from a charge-discharge rate test. It is found that rate capability is determined by ionic accessibility as well as ohmic voltage drop. A lower value in ionic accessibility for MSP20 is attributed to smaller pore diameter, longer length, and higher degree of complexity in pore structure.

  18. Impedance analysis of different cell monolayers grown on gold-film electrodes.

    Science.gov (United States)

    Reiss, Bjoern; Wegener, Joachim

    2015-08-01

    Impedance analysis of mammalian cells grown on planar film electrodes provides a label-free, non-invasive and unbiased observation of cell-based assays addressing the biological response to drugs, toxins or stressors in general. Whereas the time course of the measured impedance at one particular frequency has been used a lot for quantitative monitoring, in-depth analysis of the frequency-dependent impedance spectra is rarely performed. This study summarizes and validates the existing model for spectral analysis by applying it to eight different cell types from different mammalian tissues. Model parameters correctly predict the functional and/or structural properties of the individual cells under study. PMID:26737923

  19. Automated experiment for registration of bioelectrical potentials

    Directory of Open Access Journals (Sweden)

    D. V. Chernetchenko

    2013-11-01

    Full Text Available A hardware-software complex automated system of recording bioelectrical potentials, which is based on a USB-device with subsequent processing of signals with PC was developed in this work. We proposed a universal scheme of registration of bioelectrical potentials, which allows one to detect the reaction of biological objects to different stimuli, such as cold, heat, photo- and electrical stimulation, and to different combinations of these stimuli (Motsnyj et al., 2004. They could be applied for deeper understanding of the biological mechanisms of generation of electrical potentials in cells and discovering the accommodation processes of organisms as a whole to these stimuli. The system for registration of bioelectrical potentials consists of hardware and software parts. The software part consists of the client and server sides, which transmit experimental data to the network. The client-side software renders a quantitative analysis and stores the results in a database. An integrated system of registration and biometrical processing was applied for analysis of the electrical responses of maize leaves to heat stimuli. The dynamics of these potentials were studied and a quantitative analysis of the potential level stabilization was made. We found that amplitude relation of responses to the initial response increased and stabilized at the level of 130%. Mathematical models of the plant cell for discovering intracellular mechanisms of biopotentials registration were developed. As a result of modeling, we found that the electrical response of the cells is based on selective conductance of the cell membrane for Н+ and K+ ions. By this way, we show the biophysical relation of plant potentials to intracellular biophysical mechanisms.

  20. An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability is asses......This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability...... is assessed based on a series of Nyquist diagrams drawn for the terminal impedance of each converter. Thus, the effect of the right half-plane zeros of terminal impedances in the derivation of impedance ratio for paralleled source-source converters is avoided. The interaction between the terminal impedance...... of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical...

  1. Architecture, modeling, and analysis of a plasma impedance probe

    Science.gov (United States)

    Jayaram, Magathi

    Variations in ionospheric plasma density can cause large amplitude and phase changes in the radio waves passing through this region. Ionospheric weather can have detrimental effects on several communication systems, including radars, navigation systems such as the Global Positioning Sytem (GPS), and high-frequency communications. As a result, creating models of the ionospheric density is of paramount interest to scientists working in the field of satellite communication. Numerous empirical and theoretical models have been developed to study the upper atmosphere climatology and weather. Multiple measurements of plasma density over a region are of marked importance while creating these models. The lack of spatially distributed observations in the upper atmosphere is currently a major limitation in space weather research. A constellation of CubeSat platforms would be ideal to take such distributed measurements. The use of miniaturized instruments that can be accommodated on small satellites, such as CubeSats, would be key to achieving these science goals for space weather. The accepted instrumentation techniques for measuring the electron density are the Langmuir probes and the Plasma Impedance Probe (PIP). While Langmuir probes are able to provide higher resolution measurements of relative electron density, the Plasma Impedance Probes provide absolute electron density measurements irrespective of spacecraft charging. The central goal of this dissertation is to develop an integrated architecture for the PIP that will enable space weather research from CubeSat platforms. The proposed PIP chip integrates all of the major analog and mixed-signal components needed to perform swept-frequency impedance measurements. The design's primary innovation is the integration of matched Analog-to-Digital Converters (ADC) on a single chip for sampling the probes current and voltage signals. A Fast Fourier Transform (FFT) is performed by an off-chip Field-Programmable Gate Array (FPGA

  2. High accuracy particle analysis using sheathless microfluidic impedance cytometry.

    Science.gov (United States)

    Spencer, Daniel; Caselli, Federica; Bisegna, Paolo; Morgan, Hywel

    2016-07-01

    This paper describes a new design of microfluidic impedance cytometer enabling accurate characterization of particles without the need for focusing. The approach uses multiple pairs of electrodes to measure the transit time of particles through the device in two simultaneous different current measurements, a transverse (top to bottom) current and an oblique current. This gives a new metric that can be used to estimate the vertical position of the particle trajectory through the microchannel. This parameter effectively compensates for the non-uniform electric field in the channel that is an unavoidable consequence of the use of planar parallel facing electrodes. The new technique is explained and validated using numerical modelling. Impedance data for 5, 6 and 7 μm particles are collected and compared with simulations. The method gives excellent coefficient of variation in (electrical) radius of particles of 1% for a sheathless configuration.

  3. Design and Analysis of Impedance Pumps Utilizing Electromagnetic Actuation

    OpenAIRE

    Yu-Hisang Wang; Yao-Wen Tsai; Chien-Hsiung Tsai; Chia-Yen Lee; Lung-Ming Fu

    2010-01-01

    This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS diaphragm. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnetic diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impe...

  4. NEUROFEEDBACK INFLUENCE ON CEREBRUM BIOELECTRICAL ACTIVITY IN GYMNASTS-WOMEN

    OpenAIRE

    T. Yu. Strizhkova; Cherapkina, L. P.; O. Yu. Strizhkova

    2013-01-01

    The analysis of electroencephalogram (EEG) of highly skilled gymnasts-women (main group – 49, control group – 39) showed the availability of cerebrum bioelectrical activity features of sportswomen connected with left hemisphere dominance, predominance of theta-rhythm power and lower reaction to eyes closing, also character of neurodynamic changes generated by neurofeedback course depended on ovarian-menstrual cycle phases.

  5. Graphical analysis of electrochemical impedance spectroscopy data in Bode and Nyquist representations

    Science.gov (United States)

    Huang, Jun; Li, Zhe; Liaw, Bor Yann; Zhang, Jianbo

    2016-03-01

    Though it becomes a routine to fit impedance data to an equivalent electric circuit model (EECM) using complex nonlinear least square (CNLS) to extract physical parameters from impedance data, two formidable challenges still remain: to build a physically meaningful EECM and to find good initial estimates for model parameters. In this study, combining graphical analysis of impedance data in both Bode and Nyquist plots, a two-step procedure is proposed to address the challenges: (1) a frequency derivative phase angle method is developed in Bode plot to identify the number of time constants (or electrochemical processes); (2) graphical analysis of impedance data in Nyquist plot is used sequentially for initial parameter determination. Major graphical analysis methods are compared in terms of frequency resolution, accuracy and complexity using synthetic data. The superiority of the proposed procedure is illustrated using the experimental data of a three-electrode lithium-ion cell.

  6. Fourier-Domain Analysis of Hydriding Kinetics Using Pneumato-Chemical Impedance Spectroscopy

    OpenAIRE

    Millet, P.; C. Decaux; R. Ngameni; Guymont, M.

    2007-01-01

    Analysis of phase transformation processes observed in hydrogen absorbing materials (pure metals, alloys, or compounds) is still a matter of active research. Using pneumato-chemical impedance spectroscopy (PIS), it is now possible to analyze the mechanism of hydriding reactions induced by the gas phase. Experimental impedance diagrams, measured on activated LaNi5 in single- and two-phase domains, are reported in this paper. It is shown that their shape is mostly affected by the slope of the i...

  7. 生物电阻抗法测量7~10岁儿童总体水含量和去脂体重的预测模型%A Bioelectrical Impedance Prediction Equation for the Assessment of Total Body Water and Fat-free Mass among Chinese Children Aged 7-10 Years

    Institute of Scientific and Technical Information of China (English)

    王晓君; 胡小琪; 徐海泉; 郭向晖; 李振英; 刘爱玲

    2011-01-01

    Objective To develop the bioelectrical impedance analysis (BIA) prediction equation for the assessment of body composition among Chinese children. Methods A total of 409 children (220 boys, 189 girls) aged 7-10 years were recruited in Beijing. Body height, weight, resistance and reactance measured by BIA were collected. Total body water (TBW) and fat-free mass (FFM) measured by deuterium dilution technique was used as reference. The multiple stepwise regression analysis was employed to set up equations. Pure error (PE) and Bland-Altman approach was used to cross-validate the prediction equations. Results The prediction equation for TBW was: -6.893 + 0.410xgender(boy=l, girl=0)+0.273xage(year)+0.174xweight(kg) + 0.081 xheight(cm)+ 0.206xRI (cmVft) [R2=0.90, root mean square error (RMSE) = 1.2 kg ], and for FFM was: -9.742 +0.784x gender (boy=l, girl=0)+0.429xage(year)+0.227xweight (kg)+0.104xheight (cm) + 0.269xRI(cm2/fi) (/?2=0.90, RMSE=1.6 kg). No significant difference between predicted TBW,FFM and measured TBW,FFM was found. PE was 1.4 and 1.8 kg for TBW equation and FFM equation, respectively. However, the mean of predicted and measured TBW,FFM correlated positively with the difference between the predicted and measured values ( correlation coefficient 0.24 for TBW and 0.23 for FFM,P<0.01). The two equations performed well in different BMI groups. Conclusion The developed BIA prediction equations for the estimation of TBW and FFM have a high accuracy and precision and are valid for the assessment of body composition among Chinese children aged 7-10 years.%目的 利用生物电阻抗方法测量儿童的体成分,建立适合我国儿童体成分的预测方程.方法 在北京市采用目的抽样法选取409名7~10岁的儿童(男生220名,女生189名),测量身高和体重,采用生物电阻抗仪测量全身电阻抗和电容抗,采用单标水法测量的总体水(total body water,TBW)和去脂体重(fat-free mass,FFM)作为标准,用多元线性逐步

  8. Elliptic cylinder geometry for distinguishability analysis in impedance tomography.

    Science.gov (United States)

    Saka, Birsen; Yilmaz, Atila

    2004-01-01

    Electrical impedance tomography (EIT) is a technique that computes the cross-sectional impedance distribution within the body by using current and voltage measurements made on the body surface. It has been reported that the image reconstruction is distorted considerably when the boundary shape is considered to be more elliptical than circular as a more realistic shape for the measurement boundary. This paper describes an alternative framework for determining the distinguishability region with a finite measurement precision for different conductivity distributions in a body modeled by elliptic cylinder geometry. The distinguishable regions are compared in terms of modeling error for predefined inhomogeneities with elliptical and circular approaches for a noncircular measurement boundary at the body surface. Since most objects investigated by EIT are noncircular in shape, the analytical solution for the forward problem for the elliptical cross section approach is shown to be useful in order to reach a better assessment of the distinguishability region defined in a noncircular boundary. This paper is concentrated on centered elliptic inhomogeneity in the elliptical boundary and an analytic solution for this type of forward problem. The distinguishability performance of elliptical cross section with cosine injected current patterns is examined for different parameters of elliptical geometry. PMID:14723501

  9. Analysis of bio-anode performance through electrochemical impedance spectroscopy.

    Science.gov (United States)

    ter Heijne, Annemiek; Schaetzle, Olivier; Gimenez, Sixto; Navarro, Lucia; Hamelers, Bert; Fabregat-Santiago, Francisco

    2015-12-01

    In this paper we studied the performance of bioanodes under different experimental conditions using polarization curves and impedance spectroscopy. We have identified that the large capacitances of up to 1 mF·cm(-2) for graphite anodes have their origin in the nature of the carbonaceous electrode, rather than the microbial culture. In some cases, the separate contributions of charge transfer and diffusion resistance were clearly visible, while in other cases their contribution was masked by the high capacitance of 1 mF·cm(-2). The impedance data were analyzed using the basic Randles model to analyze ohmic, charge transfer and diffusion resistances. Increasing buffer concentration from 0 to 50mM and increasing pH from 6 to 8 resulted in decreased charge transfer and diffusion resistances; lowest values being 144 Ω·cm(2) and 34 Ω·cm(2), respectively. At acetate concentrations below 1 mM, current generation was limited by acetate. We show a linear relationship between inverse charge transfer resistance at potentials close to open circuit and saturation (maximum) current, associated to the Butler-Volmer relationship that needs further exploration.

  10. Robot impedance control and passivity analysis with inner torque and velocity feedback loops

    Institute of Scientific and Technical Information of China (English)

    Michele FOCCHI; Gustavo A MEDRANO-CERDA; Thiago BOAVENTURA; Marco FRIGERIO; Claudio SEMINI; Jonas BUCHLI; Darwin G CALDWELL

    2016-01-01

    Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. In particular, the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops (e.g., a torque loop) as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase (given the constraints to preserve stability) the bandwidth of the torque loop without the need of a complex controller.

  11. Sugarcane bio ethanol and bioelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Luiz Augusto Horta; Leal, Manoel Regis Lima Verde

    2012-07-01

    This chapter approaches the Brazilian sugar cane production and processing model, sugarcane processing, sugarcane reception, sugarcane preparation and juice extraction, juice treatment, fermentation, distillation, sector efficiencies and future improvement - 2007, 2015 and 2025, present situation (considering the 2007/2008 harvesting season), prospective values for 2015 and for 2025, bioelectricity generation, straw recovery, bagasse availability, energy balance, present situation, perspective for improvements in the GHG mitigation potential, bio ethanol production chain - from field to tank, and surplus electricity generation.

  12. Analytical Model for High Impedance Fault Analysis in Transmission Lines

    Directory of Open Access Journals (Sweden)

    S. Maximov

    2014-01-01

    Full Text Available A high impedance fault (HIF normally occurs when an overhead power line physically breaks and falls to the ground. Such faults are difficult to detect because they often draw small currents which cannot be detected by conventional overcurrent protection. Furthermore, an electric arc accompanies HIFs, resulting in fire hazard, damage to electrical devices, and risk with human life. This paper presents an analytical model to analyze the interaction between the electric arc associated to HIFs and a transmission line. A joint analytical solution to the wave equation for a transmission line and a nonlinear equation for the arc model is presented. The analytical model is validated by means of comparisons between measured and calculated results. Several cases of study are presented which support the foundation and accuracy of the proposed model.

  13. Electrochemical impedance spectroscopy on in-situ analysis of oxide layer formation in liquid metal

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, M., E-mail: kondo.masatoshi@tokai-u.jp [Department of Nuclear Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Suzuki, N.; Nakajima, Y. [Department of Nuclear Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Tanaka, T.; Muroga, T. [National Institute for Fusion Science, Toki, Gifu 502-5292 (Japan)

    2014-10-15

    Graphical abstract: Some test materials (i.e. Fe, Cr, Y and JLF-1 steel) were immersed to liquid metal lead (Pb) mainly at 773 K as the working electrode of electrochemical impedance spectroscopy (EIS). Some oxide layers formed on the electrodes in liquid Pb were analyzed by EIS. The impedance response was summarized as semicircular Nyquist plot, and the electrical properties and the thickness of the oxide layers were evaluated in non-destructive manner. Large impedance due to the formation of Y oxide formed in liquid Pb was detected by EIS, though impedance of Fe oxide and Cr oxide could not be detected due to their small electro resistance. The time constant of the oxide layers was evaluated from the impedance information, and this value identified the types of oxides. The change of the time constant with the immersion time indicated the change of the electrical properties determined by the chemical composition and the crystal structure. The thickness of the oxide layer estimated by EIS agreed well with that evaluated by metallurgical analysis. The growth of Y oxide layer in the liquid Pb was successfully detected by EIS in non-destructive manner. - Highlights: • The electrical properties and the thickness of lead oxide layer formed in liquid Pb were obtained by electrochemical impedance spectroscopy (EIS). • The Fe oxide, Cr oxide and Fe–Cr oxide formed on the electrodes in liquid Pb were not detected by EIS due to their small electrical resistance. • The formation and the growth of Y oxide formed in liquid Pb was detected by EIS. - Abstract: Some test materials (i.e. Fe, Cr, Y and JLF-1 steel) were immersed to liquid metal lead (Pb) mainly at 773 K as the working electrode of electrochemical impedance spectroscopy (EIS). Some oxide layers formed on the electrodes in liquid Pb were analyzed by EIS. The impedance response was summarized as Nyquist plot, and the electrical properties and the thickness of the oxide layers were evaluated in non

  14. Coupling of impedance functions to nuclear reactor building for soil-structure interaction analysis

    International Nuclear Information System (INIS)

    Finite element model of a nuclear reactor building is coupled to complex soil impedance functions and soil-structure-interaction analysis is carried out in frequency domain. In the second type of analysis applied in this paper, soil impedance functions are used to evaluate equivalent soil springs and dashpots of soil. These are coupled to the structure model in order to carry out the time marching analysis. Three types of soil profiles are considered: hard, medium and soft. Results of two analyzes are compared on the same structural model. Equivalent soil springs and dashpots are determined using new method based on the least square approximation. (author)

  15. Measuring Electrolyte Impedance and Noise Simultaneously by Triangular Waveform Voltage and Principal Component Analysis

    Directory of Open Access Journals (Sweden)

    Shanzhi Xu

    2016-04-01

    Full Text Available In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA. Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface.

  16. Measuring Electrolyte Impedance and Noise Simultaneously by Triangular Waveform Voltage and Principal Component Analysis.

    Science.gov (United States)

    Xu, Shanzhi; Wang, Peng; Dong, Yonggui

    2016-01-01

    In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA). Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface. PMID:27110787

  17. Application of impedance spectroscopy method for analysis of benzanol fuels

    Directory of Open Access Journals (Sweden)

    Mamykin A. V.

    2015-06-01

    Full Text Available The authors have developed a method for express control of three component «gasoline-alcohol-water» fuel mixtures based on the spectral impedance investigation of benzanol mixture in the frequency range of 500 Hz — 10 kHz. A correlation dependence between the dielectric constant and the specific resistance of the fuel mixture on content of ethanol and water in the mixture has been found. On the basis of this dependence a calibration nomogram to quantify the gasoline and water-alcohol components content in the test benzanol fuel in the actual range of concentrations has been formed. The nomogram allows determining the water-alcohol and gasoline parts in the analyzed fuel with an error of no more than 1% vol., while the strength of water-alcohol solution is determined with an error of no more than 0.8% vol. The obtained nomogram can also give information about critical water content in the benzanol fuel to prevent its eventual phase separation. It is shown that the initial component composition of different gasoline brands has no significant effect on the electrical characteristics of the studied benzanol fuels, which makes the evaluation of alcohol and water content in the fuel sufficiently accurate. for practical applications.

  18. Power flow analysis for droop controlled LV hybrid AC-DC microgrids with virtual impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos;

    2014-01-01

    and virtual impedance concepts for AC network, DC network and interlinking converter are reviewed so as to model it in the power flow analysis. The validation of the algorithm is verified by comparing it with steady state results from detailed time domain simulation. The effectiveness of the proposed......The AC-DC hybrid microgrid is an effective form of utilizing different energy resources and the analysis of this system requires a proper power flow algorithm. This paper proposes a suitable power flow algorithm for LV hybrid AC-DC microgrid based on droop control and virtual impedance. Droop...

  19. Impedance-matching analysis in IR leaky-wave antennas

    Science.gov (United States)

    Premkumar, Navaneeth; Xu, Yuancheng; Lail, Brian A.

    2015-08-01

    Planar leaky-wave antennas (LWA) that are capable of full-space scanning have long since been the pursuit for applications including, but not limited to, integration onto vehicles and into cameras for wide-angle of view beam-steering. Such a leaky-wave surface (LWS) was designed for long-wave infrared frequencies with frequency scanning capability. The LWS is based on a microstrip patch array design of a leaky-wave impedance surface and is made up of gold microstrip patches on a grounded zinc sulphide substrate. A 1D composite right/left-handed (CRLH) metamaterial made by periodically stacking a unit cell of the LWS in the longitudinal direction to form a LWA was designed. This paper deals with loading the LWA with a nickel bolometer to collect leaky-wave signals. The LWA radiates a backward leaking wave at 30 degrees at 28.3THz and scans through broadside for frequencies 20THz through 40THz. The paper deals with effectively placing the bolometer in order for the collected signal to exhibit the designed frequency regime. An effective way to maximize the power coupling into the load from the antenna is also explored. The benefit of such a metamaterial/holographic antennacoupled detector is its ability to provide appreciable capture cross-sections while delivering smart signals to subwavelength sized detectors. Due to their high-gain, low-profile, fast response time of the detector and ease of fabrication, this IR LWA-coupled bolometer harbors great potential in the areas of high resolution, uncooled, infrared imaging.

  20. Bioelectrical impedance and visceral fat: a comparison with computed tomography in adults and elderly; Bioimpedancia eletrica e gordura visceral: uma comparacao com a tomografia computadorizada em adultos e idosos

    Energy Technology Data Exchange (ETDEWEB)

    Eickemberg, Michaela [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Roriz, Anna Karla Carneiro [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Fontes, Gardenia Abreu Vieira [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Sampaio, Lilian Ramos [Universidade Federal de Sao Paulo (Unifesp), Sao Paulo, SP (Brazil)

    2013-05-01

    Objective: To evaluate the association between electrical bioimpedance analysis (BIA) and visceral fat (VF) in adult and elderly patients. Subjects and methods: This was a cross-sectional study, with a sample of 191 subjects (52% women, 49% elderly) stratified by sex, age and body mass. Computerized tomography (VF area) and BIA (percentage of total body fat (%TBF-BIA), phase angle, reactance and resistance) data were generated. Statistical analysis was based on Pearson's Correlation Coefficient, Anova, Pearson's Chi-square, and ROC curves. Results: VF areas {>=} 130 cm{sup 2} were more prevalent among the elderly and among men. Adult females showed a stronger correlation between GV and %TBF-BIA. The other groups showed similar results and statistically significant correlations. Correlations between GV and phase angle were weak and not statistically significant. ROC Curves analyzes showed the following %TBF-BIA, which identified excess VF: for male subjects: 21.5% (adults) and 24.25% (elderly); for female subjects: 35.05% (adults) and 38.45% (elderly) with sensitivity of 78.6%, 82.1%, 83.3%, and 66.7%, and specificity of 70.6%, 62.5%, 79.1%, and 69%, respectively. Conclusion: BIA was found to have satisfactory sensitivity and specificity to predict VF; however, other devices and other techniques should be investigated to improve VF prediction. (author)

  1. Time-invariant measurement of time-varying bioimpedance using vector impedance analysis.

    Science.gov (United States)

    Sanchez, B; Louarroudi, E; Pintelon, R

    2015-03-01

    When stepped-sine impedance spectroscopy measurements are carried out on (periodically) time-varying bio-systems, the inherent time-variant (time-periodic) parts are traditionally ignored or mitigated by filtering. The latter, however, lacks theoretical foundation and, in this paper, it is shown that it only works under certain specific conditions. Besides, we propose an alternative method, based on multisine signals, that exploits the non-stationary nature in time-varying bio-systems with a dominant periodic character, such as cardiovascular and respiratory systems, or measurements interfered with by their physiological activities. The novel method extracts the best—in a mean square sense—linear time-invariant (BLTI) impedance approximation ZBLTI(jω) of a periodically time-varying (PTV) impedance ZPTV(jω, t) as well as its time-periodic part. Relying on the geometrical interpretation of the BLTI concept, a new impedance analysis tool, called vector impedance analysis (VIA), is also presented. The theoretical and practical aspects are validated through measurements performed on a PTV dummy circuit and on an in vivo myocardial tissue. PMID:25700023

  2. Analysis of the Impedance Resonance of Piezoelectric Multi-Fiber Composite Stacks

    Science.gov (United States)

    Sherrit, S.; Djrbashian, A.; Bradford, S C

    2013-01-01

    Multi-Fiber CompositesTM (MFC's) produced by Smart Materials Corp behave essentially like thin planar stacks where each piezoelectric layer is composed of a multitude of fibers. We investigate the suitability of using previously published inversion techniques for the impedance resonances of monolithic co-fired piezoelectric stacks to the MFCTM to determine the complex material constants from the impedance data. The impedance equations examined in this paper are those based on the derivation. The utility of resonance techniques to invert the impedance data to determine the small signal complex material constants are presented for a series of MFC's. The technique was applied to actuators with different geometries and the real coefficients were determined to be similar within changes of the boundary conditions due to change of geometry. The scatter in the imaginary coefficient was found to be larger. The technique was also applied to the same actuator type but manufactured in different batches with some design changes in the non active portion of the actuator and differences in the dielectric and the electromechanical coupling between the two batches were easily measureable. It is interesting to note that strain predicted by small signal impedance analysis is much lower than high field stains. Since the model is based on material properties rather than circuit constants, it could be used for the direct evaluation of specific aging or degradation mechanisms in the actuator as well as batch sorting and adjustment of manufacturing processes.

  3. Effects of Nitrogen on Passivity of Nickel-Free Stainless Steels by Electrochemical Impedance Spectroscopy Analysis

    Science.gov (United States)

    Wu, Xinqiang; Fu, Yao; Ke, Wei; Xu, Song; Feng, Bing; Hu, Botao

    2015-09-01

    The effects of different nitrogen contents on the passivity of nickel-free stainless steels in 0.5 M sulfuric acid + 0.5 M sodium chloride solution were investigated by electrochemical impedance spectroscopy in the potential ranges of active dissolution and active-passive transition. A simplified reaction model containing adsorbed intermediates involved dissolution process, and passivation process was proposed to explain the impedance characteristics. Based on both equivalent circuit and mathematical model analysis, the effects of nitrogen on the passivity of stainless steels are discussed.

  4. Simultaneous Impedance Analysis of Three Parallel Piezoelectric Quartz Crystals for Electrochemical Depletion Layer Effect Study

    Institute of Scientific and Technical Information of China (English)

    Hui Yan liu; Qing Ji XIE

    2004-01-01

    Simultaneous impedance analysis of three one-face sealed resonating piezoelectric quartz crystals (PQCs) in parallel is proposed through admittance measurements of the three PQCs on one impedance analyzer and then non-linear fitting according to the parallel combination of three Butterworth-Van Dyke circuits. Responses of each PQC obtained from the three-PQC mode agreed well with those measured separately in series sucrose aqueous solutions. This novel method has been used for the study of depletion-layer effect during ferri-/ferrocyanide electrochemical reactions.

  5. Conductometric analysis in bio-applications: A universal impedance spectroscopy-based approach using modified electrodes

    DEFF Research Database (Denmark)

    Canali, Chiara; Larsen, Layla Bashir; Grøttem Martinsen, Ørjan;

    2015-01-01

    We present a universal protocol for quick and reproducible conductivity determinations in bio-applications using electrochemical impedance spectroscopy (EIS), electrode modification and automate spectral analysis. Two-terminal EIS measurements may be acquired using any standard impedance analyser...... impedance. Conducted measurements showed high reproducibility in good agreement with a commercial conductometer in a wide range of ionic strengths up to five times that of physiological PBS. Since measurements in cell culture medium with bare gold electrodes indicated the need for recalibration......). The corresponding conductivity value is immediately calculated as the ratio of the conductivity cell constant(K), determined based on calibration, and RS. This protocol eliminates the need for evaluating a specific equivalent circuit followed by non-linear regression based curve fitting that is generally required...

  6. Small Signal Modeling and Comprehensive Analysis of Magnetically Coupled Impedance Source Converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Blaabjerg, Frede;

    2016-01-01

    applications; however, due to effective role of system modeling in the closed-loop controller design, this paper is allocated to small-signal modeling and analysis of MCIS converters. The modeling is performed by means of the circuit averaging and averaged switch technique. A generalized small......Magnetically coupled impedance-source (MCIS) networks are recently introduced impedance networks intended for various high-boost applications. It employs coupled magnetic in the circuit to achieve higher voltage gain. Various MCIS networks have been proposed in the literature for myriad......-signal derivation is demonstrated for pulse width modulation (PWM) MCIS converters and it is shown that the derived transfer functions can simply be applied to Y-source, Γ-source, and T-source impedance networks. Various transfer functions for capacitor voltage, output voltage, magnetizing current, input and output...

  7. Impedances of an Infinitely Long and Axisymmetric Multilayer Beam Pipe: Matrix Formalism and Multimode Analysis

    CERN Document Server

    Mounet, N

    2010-01-01

    Using B. Zotter’s formalism, we present here a novel, efficient and exact matrix method for the field matching determination of the electromagnetic field components created by an offset point charge travelling at any speed in an infinitely long circular multilayer beam pipe. This method improves by a factor of more than one hundred the computational time with three layers and allows the computation for more layers than three. We also generalize our analysis to any azimuthal mode and finally perform the summation on all such modes in the impedance formulae. In particular the exact multimode direct space-charge impedances (both longitudinal and transverse) are given, as well as the wall impedance to any order of precision.

  8. Seismic soil-structure interaction analysis of embedded multiple buildings using the hybrid continuum impedance approach

    International Nuclear Information System (INIS)

    Seismic Soil-Structure Interaction (SSI) analysis has been performed for a site with deeply embedded multiple power block structures. The new method employed combines the computational advantages of the Continuum Impedance Approach together with the Substructure Deletion/Boundary Element Method to accurately predict the 3-Dimensional seismic response of structures. (author)

  9. A Practical Approach for Analysis of Input and Output Impedances of Feedback Amplifiers

    Science.gov (United States)

    Abramovitz, A.

    2009-01-01

    This paper suggests a pedagogical approach to teaching the subject of the analysis of feedback amplifiers for electrical engineering students at the undergraduate level. Special attention is given to derivation of the input and output impedances. In order to make the procedure clear and suitable for classroom presentation an alternative proof of…

  10. Bioelectric modulation of macrophage polarization

    Science.gov (United States)

    Li, Chunmei; Levin, Michael; Kaplan, David L.

    2016-02-01

    Macrophages play a critical role in regulating wound healing and tissue regeneration by changing their polarization state in response to local microenvironmental stimuli. The native roles of polarized macrophages encompass biomaterials and tissue remodeling needs, yet harnessing or directing the polarization response has been largely absent as a potential strategy to exploit in regenerative medicine to date. Recent data have revealed that specific alteration of cells’ resting potential (Vmem) is a powerful tool to direct proliferation and differentiation in a number of complex tissues, such as limb regeneration, craniofacial patterning and tumorigenesis. In this study, we explored the bioelectric modulation of macrophage polarization by targeting ATP sensitive potassium channels (KATP). Glibenclamide (KATP blocker) and pinacidil (KATP opener) treatment not only affect macrophage polarization, but also influence the phenotype of prepolarized macrophages. Furthermore, modulation of cell membrane electrical properties can fine-tune macrophage plasticity. Glibenclamide decreased the secretion and gene expression of selected M1 markers, while pinacidil augmented M1 markers. More interestingly, glibencalmide promoted macrophage alternative activation by enhancing certain M2 markers during M2 polarization. These findings suggest that control of bioelectric properties of macrophages could offer a promising approach to regulate macrophage phenotype as a useful tool in regenerative medicine.

  11. NEUROFEEDBACK INFLUENCE ON CEREBRUM BIOELECTRICAL ACTIVITY IN GYMNASTS-WOMEN

    Directory of Open Access Journals (Sweden)

    T. Yu. Strizhkova

    2013-01-01

    Full Text Available The analysis of electroencephalogram (EEG of highly skilled gymnasts-women (main group – 49, control group – 39 showed the availability of cerebrum bioelectrical activity features of sportswomen connected with left hemisphere dominance, predominance of theta-rhythm power and lower reaction to eyes closing, also character of neurodynamic changes generated by neurofeedback course depended on ovarian-menstrual cycle phases.

  12. A package for impedance/admittance data analysis

    NARCIS (Netherlands)

    Boukamp, Bernard A.

    1986-01-01

    An outline is given of a Basic computer program which facilitates the analysis of frequency dispersion data. With this program an equivalent circuit, and starting values for the corresponding circuit parameters, can be extracted from the dispersion data. A circuit description together with crude par

  13. Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, M P; Ong, M M; Brown, C G; Speer, R D

    2011-07-20

    It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations, and finite conductivity of the shield. In order to perform an analysis of such a structure it is important to first determine the effect of the finite impedance of the conductors used in the shield. In this paper we will discuss the impedances of different cylindrical conductors in the time domain. For a time varying pulse the currents created in the conductor will have different spectral components, which will affect the current density due to skin effects. Many construction materials use iron and different types of steels that have a nonlinear permeability. The nonlinear material can have an effect on the impedance of the conductor depending on the B-H curve. Although closed form solutions exist for the impedances of cylindrical conductors made of linear materials, computational techniques are needed for nonlinear materials. Simulations of such impedances are often technically challenging due to the need for a computational mesh to be able to resolve the skin depths for the different spectral components in the pulse. The results of such simulations in the time domain will be shown and used to determine the impedances of cylindrical conductors for lightning current pulses that have low frequency content.

  14. Electrochemical impedance analysis of spray deposited CZTS thin film: Effect of Se introduction

    Science.gov (United States)

    Patil, Swati J.; Lokhande, Vaibhav C.; Lee, Dong-Weon; Lokhande, Chandrakant D.

    2016-08-01

    The present work deals with electrochemical impedance analysis of spray deposited Cu2ZnSnS4 (CZTS) thin films grown on fluorine doped tin oxide (FTO) substrates and effect of post Se introduction. The CZTS thin films are characterized using X-ray diffraction (XRD), X-Ray photo spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and UV-Vis spectroscopy techniques. The electrochemical measurements are carried out using impedance analysis spectroscopy. The strong peak in XRD pattern along (112) plane confirms the Kestrite crystal structure of CZTS film. The FE-SEM analysis reveals that nanoflakes contain crack-free surface microstructure changes with post Se introucation. The optical study reveals that absorption increases with Se dipping time and observed lower band gap of 1.31 eV. Introduction of Se in CZTS film results an improvement in the grain size and surface morphology which leads to increased electrical conductivity of CZTS film.

  15. Determination of bone mineral volume fraction using impedance analysis and Bruggeman model

    Energy Technology Data Exchange (ETDEWEB)

    Ciuchi, Ioana Veronica; Olariu, Cristina Stefania, E-mail: oocristina@yahoo.com; Mitoseriu, Liliana, E-mail: lmtsr@uaic.ro

    2013-11-20

    Highlights: • Mineral volume fraction of a bone sample was determined. • Dielectric properties for bone sample and for the collagen type I were determined by impedance spectroscopy. • Bruggeman effective medium approximation was applied in order to evaluate mineral volume fraction of the sample. • The computed values were compared with ones derived from a histogram test performed on SEM micrographs. -- Abstract: Measurements by impedance spectroscopy and Bruggeman effective medium approximation model were employed in order to determine the mineral volume fraction of dry bone. This approach assumes that two or more phases are present into the composite: the matrix (environment) and the other ones are inclusion phases. A fragment of femur diaphysis dense bone from a young pig was investigated in its dehydrated state. Measuring the dielectric properties of bone and its main components (hydroxyapatite and collagen) and using the Bruggeman approach, the mineral volume filling factor was determined. The computed volume fraction of the mineral volume fraction was confirmed by a histogram test analysis based on the SEM microstructures. In spite of its simplicity, the method provides a good approximation for the bone mineral volume fraction. The method which uses impedance spectroscopy and EMA modeling can be further developed by considering the conductive components of the bone tissue as a non-invasive in situ impedance technique for bone composition evaluation and monitoring.

  16. Numerical analysis of acoustic impedance microscope utilizing acoustic lens transducer to examine cultured cells.

    Science.gov (United States)

    Gunawan, Agus Indra; Hozumi, Naohiro; Takahashi, Kenta; Yoshida, Sachiko; Saijo, Yoshifumi; Kobayashi, Kazuto; Yamamoto, Seiji

    2015-12-01

    A new technique is proposed for non-contact quantitative cell observation using focused ultrasonic waves. This technique interprets acoustic reflection intensity into the characteristic acoustic impedance of the biological cell. The cells are cultured on a plastic film substrate. A focused acoustic beam is transmitted through the substrate to its interface with the cell. A two-dimensional (2-D) reflection intensity profile is obtained by scanning the focal point along the interface. A reference substance is observed under the same conditions. These two reflections are compared and interpreted into the characteristic acoustic impedance of the cell based on a calibration curve that was created prior to the observation. To create the calibration curve, a numerical analysis of the sound field is performed using Fourier Transforms and is verified using several saline solutions. Because the cells are suspended by two plastic films, no contamination is introduced during the observation. In a practical observation, a sapphire lens transducer with a center frequency of 300 MHz was employed using ZnO thin film. The objects studied were co-cultured rat-derived glial (astrocyte) cells and glioma cells. The result was the clear observation of the internal structure of the cells. The acoustic impedance of the cells was spreading between 1.62 and 1.72 MNs/m(3). Cytoskeleton was indicated by high acoustic impedance. The introduction of cytochalasin-B led to a significant reduction in the acoustic impedance of the glioma cells; its effect on the glial cells was less significant. It is believed that this non-contact observation method will be useful for continuous cell inspections.

  17. Complex impedance and equivalent bolometer, analysis of a low noise bolometer for SAFARI

    OpenAIRE

    Lindeman, M.A.; Khosropanah, P.; Hijmering, R.A.; De Ridder, M.; Gottardi, L; de Bruijn, M; van der Kuur, J; de Korte, P.A.J.; Gao, J. R.; Hoevers, H.

    2012-01-01

    Transition-edge-sensor (TES) bolometers are the chosen detector technology for the SAFARI Imaging Spectrometer on the SPICA telescope. For this mission, SRON is developing bolometers, each consisting of a TiAu TES that is weakly coupled to the thermal bath through thin legs of silicon nitride. In order to understand and optimize the bolometer and to verify our detector models, we characterize the devices using a series of complex impedance measurements. We apply equivalent bolometer analysis ...

  18. Label-free single cell analysis with a chip-based impedance flow cytometer

    Science.gov (United States)

    Pierzchalski, Arkadiusz; Hebeisen, Monika; Mittag, Anja; Di Berardino, Marco; Tarnok, Attila

    2010-02-01

    For description of cellular phenotypes and physiological states new developments are needed. Axetris' impedance flow cytometer (IFC) (Leister) is a new promising label-free alternative to fluorescence-based flow cytometry (FCM). IFC measures single cells at various frequencies simultaneously. The frequencies used for signal acquisition range from 0.1 to 20 MHz. The impedance signal provides information about cell volume (ionophore valinomycin. Changes in membrane potential were detectable at the level of cytoplasm conductivity (>4 MHz) and membrane capacitance (1-4 MHz). Our data indicate that IFC can be a valuable alternative to conventional FCM for various applications in the field of cell death and physiology. The work will be extended to address further potential applications of IFC in biotechnology and biomedical cell analysis, as well as in cell sorting.

  19. Electrical Impedance Analysis of Mammalian Cells Cultured on Polypyrrole-modified Gold Microlectrodes

    Science.gov (United States)

    Chen, Guo; Keese, Charles R.; Giaever, Ivar

    2003-03-01

    In the present study we describe an electrical impedance analysis of BSC cells cultured on gold electrodes (250 im in diameter) that were modified with polypyrrole/heparin composites using electrochemical deposition. Atomic force microscope images show that the composite layer has a porous bulk structure and a very rough surface topology. An electrical technique, referred to as ECIS, was used to measure the impedance of both the cell-covered and the cell-free microelectrodes at frequencies from 25 Hz to 60000 Hz. The electrical characteristics of the system can be modeled with 3 parameters, the intercellular resistance (R_b), the cellular membrane (C_m) and the cell-substrate separation (α). When cells are cultured on the polypyrrole-modified microelectrodes, the contribution to the total resistance from α is decreased, which opens a way to eliminate the contribution arising from α so that Rb and Cm can be directly measured.

  20. Role of radiation damping in the impedance function approach to soil-structure interaction analysis

    International Nuclear Information System (INIS)

    This report was prepared at the request of the Lawrence Livermore Laboratory (LLL) to provide background information for analyzing soil-structure interaction by the frequency-independent impedance function approach. LLL is conducting such analyses as part of its seismic review of selected operating plants under the Systematic Evaluation Program for the US Nuclear Regulatory Commission. The analytical background and basic assumptionsof the impedance function theory are briefly reviewed, and the role of radiation damping in soil-structure interaction analysis is discussed. The validity of modeling soil-structure interaction by using frequency-independent functions is evaluated based on data from several field tests. Finally, the recommended procedures for performing soil-structure interaction analyses are discussed with emphasis on the modal superposition method

  1. Electrochemical Impedance Spectroscopic Analysis of RuO2 Based Thick Film pH Sensors

    International Nuclear Information System (INIS)

    The conductimetric interdigitated thick film pH sensors based on RuO2 were fabricated and their electrochemical reactions with solutions of different pH values were studied by electrochemical impedance spectroscopy (EIS) technique. The microstructural properties and composition of the sensitive films were examined by scanning electron microscopy, X-ray energy dispersive spectroscopy and Raman spectroscopy. The EIS analysis of the sensor was carried out in the frequency range 10 mHz–2 MHz for pH values of test solutions 2–12. The electrical parameters of the sensor were found to vary with changing pH. The conductance and capacitance of the film were distinctly dependent on pH in the low frequency range. The Nyquist and Bode plots derived from the impedance data for the metal oxide thick film pH sensor provided information about the underlying electrochemical reactions

  2. Hardware Design of Tuber Electrical Resistance Tomography System Based on the Soil Impedance Test and Analysis

    Directory of Open Access Journals (Sweden)

    Liu Shuyi

    2016-01-01

    Full Text Available The hardware design of tuber electrical resistance tomography (TERT system is one of the key research problems of TERT data acquisition system. The TERT system can be applied to the tuber growth process monitoring in agriculture, i.e., the TERT data acquisition system can realize the real imaging of tuber plants in soil. In TERT system, the imaging tuber and soil multiphase medium is quite complexity. So, the impedance test and analysis of soil multiphase medium is very important to the design of sensitive array sensor subsystem and signals processing circuits. In the paper, the soil impedance test experimental is described and the results are analysed. The data acquisition hardware system is designed based on the result of soil medium impedance test and analysis. In the hardware design, the switch control chip ADG508, the instrumentation amplifier AD620 and programmable amplifier AD526 are employed. In the meantime, the phase locked loop technique for signal demodulation is introduced. The initial data collection is given and discussed under the conditions of existing plant tuber and no existing plant tuber. Conclusions of the hardware design of TERT system are presented.

  3. Hemodynamics analysis of patient-specific carotid bifurcation: a CFD model of downstream peripheral vascular impedance.

    Science.gov (United States)

    Dong, Jingliang; Wong, Kelvin K L; Tu, Jiyuan

    2013-04-01

    The study of cardiovascular models was presented in this paper based on medical image reconstruction and computational fluid dynamics. Our aim is to provide a reality platform for the purpose of flow analysis and virtual intervention outcome predication for vascular diseases. By connecting two porous mediums with transient permeability at the downstream of the carotid bifurcation branches, a downstream peripheral impedance model was developed, and the effect of the downstream vascular bed impedance can be taken into consideration. After verifying its accuracy with a healthy carotid bifurcation, this model was implemented in a diseased carotid bifurcation analysis. On the basis of time-averaged wall shear stress, oscillatory shear index, and the relative residence time, fractions of abnormal luminal surface were highlighted, and the atherosclerosis was assessed from a hemodynamic point of view. The effect of the atherosclerosis on the transient flow division between the two branches because of the existence of plaque was also analysed. This work demonstrated that the proposed downstream peripheral vascular impedance model can be used for computational modelling when the outlets boundary conditions are not available, and successfully presented the potential of using medical imaging and numerical simulation to provide existing clinical prerequisites for diagnosis and therapeutic treatment.

  4. Computer program for analysis of impedance cardiography signals enabling manual correction of points detected automatically

    Science.gov (United States)

    Oleksiak, Justyna; Cybulski, Gerard

    2014-11-01

    The aim of this work was to create a computer program, written in LabVIEW, which enables the visualization and analysis of hemodynamic parameters. It allows the user to import data collected using ReoMonitor, an ambulatory monitoring impedance cardiography (AICG) device. The data include one channel of the ECG and one channel of the first derivative of the impedance signal (dz/dt) sampled at 200Hz and the base impedance signal (Z0) sampled every 8s. The program consist of two parts: a bioscope allowing the presentation of traces (ECG, AICG, Z0) and an analytical portion enabling the detection of characteristic points on the signals and automatic calculation of hemodynamic parameters. The detection of characteristic points in both signals is done automatically, with the option to make manual corrections, which may be necessary to avoid "false positive" recognitions. This application is used to determine the values of basic hemodynamic variables: pre-ejection period (PEP), left ventricular ejection time (LVET), stroke volume (SV), cardiac output (CO), and heart rate (HR). It leaves room for further development of additional features, for both the analysis panel and the data acquisition function.

  5. Fast and sensitive detection of foodborne pathogen using electrochemical impedance analysis, urease catalysis and microfluidics.

    Science.gov (United States)

    Chen, Qi; Wang, Dan; Cai, Gaozhe; Xiong, Yonghua; Li, Yuntao; Wang, Maohua; Huo, Huiling; Lin, Jianhan

    2016-12-15

    Early screening of pathogenic bacteria is a key to prevent and control of foodborne diseases. In this study, we developed a fast and sensitive bacteria detection method integrating electrochemical impedance analysis, urease catalysis with microfluidics and using Listeria as model. The Listeria cells, the anti-Listeria monoclonal antibodies modified magnetic nanoparticles (MNPs), and the anti-Listeria polyclonal antibodies and urease modified gold nanoparticles (AuNPs) were incubated in a fluidic separation chip with active mixing to form the MNP-Listeria-AuNP-urease sandwich complexes. The complexes were captured in the separation chip by applying a high gradient magnetic field, and the urea was injected to resuspend the complexes and hydrolyzed under the catalysis of the urease on the complexes into ammonium ions and carbonate ions, which were transported into a microfluidic detection chip with an interdigitated microelectrode for impedance measurement to determine the amount of the Listeria cells. The capture efficiency of the Listeria cells in the separation chip was ∼93% with a shorter time of 30min due to the faster immuno-reaction using the active magnetic mixing. The changes on both impedance magnitude and phase angle were demonstrated to be able to detect the Listeria cells as low as 1.6×10(2)CFU/mL. The detection time was reduced from original ∼2h to current ∼1h. The recoveries of the spiked lettuce samples ranged from 82.1% to 89.6%, indicating the applicability of this proposed biosensor. This microfluidic impedance biosensor has shown the potential for online, automatic and sensitive bacteria separation and detection.

  6. Bioelectric signaling regulates size in zebrafish fins.

    Directory of Open Access Journals (Sweden)

    Simon Perathoner

    2014-01-01

    Full Text Available The scaling relationship between the size of an appendage or organ and that of the body as a whole is tightly regulated during animal development. If a structure grows at a different rate than the rest of the body, this process is termed allometric growth. The zebrafish another longfin (alf mutant shows allometric growth resulting in proportionally enlarged fins and barbels. We took advantage of this mutant to study the regulation of size in vertebrates. Here, we show that alf mutants carry gain-of-function mutations in kcnk5b, a gene encoding a two-pore domain potassium (K(+ channel. Electrophysiological analysis in Xenopus oocytes reveals that these mutations cause an increase in K(+ conductance of the channel and lead to hyperpolarization of the cell. Further, somatic transgenesis experiments indicate that kcnk5b acts locally within the mesenchyme of fins and barbels to specify appendage size. Finally, we show that the channel requires the ability to conduct K(+ ions to increase the size of these structures. Our results provide evidence for a role of bioelectric signaling through K(+ channels in the regulation of allometric scaling and coordination of growth in the zebrafish.

  7. Combined impedance and dielectrophoresis portable device for point-of-care analysis

    Science.gov (United States)

    del Moral Zamora, B.; Colomer-Farrarons, J.; Mir-Llorente, M.; Homs-Corbera, A.; Miribel-Català, P.; Samitier-Martí, J.

    2011-05-01

    In the 90s, efforts arise in the scientific world to automate and integrate one or several laboratory applications in tinny devices by using microfluidic principles and fabrication technologies used mainly in the microelectronics field. It showed to be a valid method to obtain better reactions efficiency, shorter analysis times, and lower reagents consumption over existing analytical techniques. Traditionally, these fluidic microsystems able to realize laboratory essays are known as Lab-On-a-Chip (LOC) devices. The capability to transport cells, bacteria or biomolecules in an aqueous medium has significant potential for these microdevices, also known as micro-Total-Analysis Systems (uTAS) when their application is of analytical nature. In particular, the technique of dielectrophoresis (DEP) opened the possibility to manipulate, actuate or transport such biological particles being of great potential in medical diagnostics, environmental control or food processing. This technique consists on applying amplitude and frequency controlled AC signal to a given microsystem in order to manipulate or sort cells. Furthermore, the combination of this technique with electrical impedance measurements, at a single or multiple frequencies, is of great importance to achieve novel reliable diagnostic devices. This is because the sorting and manipulating mechanism can be easily combined with a fully characterizing method able to discriminate cells. The paper is focused in the electronics design of the quadrature DEP generator and the four-electrode impedance measurement modules. These together with the lab-on-a-chip device define a full conception of an envisaged Point-of-Care (POC) device.

  8. Equivalent circuit model analysis on electrochemical impedance spectroscopy of lithium metal batteries

    Science.gov (United States)

    Gao, Peng; Zhang, Cuifen; Wen, Guangwu

    2015-10-01

    Lithium metal electrode is pretreated with 1,3-dioxolane or 1,4-dioxane to improve its properties. The components and morphology of the surface films formed in the above two pretreatment liquids are studied using FTIR and SEM respectively. Li-LiCoO2 coin cells are then fabricated and their cycle and discharge performance are tested. It is found that the battery performance is greatly improved by such pretreatment. Interestingly, the 1,4-dioxane pretreatment is more effective than 1,3-dioxolane in improving the lithium metal electrode performance. To explore the mechanism(s) behind, the electrochemical impedance spectroscopy (EIS) is employed and an equivalent circuit model is designed for EIS analysis. The fitting curves are aligned well with the experimental curves, suggesting that the proposed equivalent circuit model is an ideal model for lithium battery. Next, the corresponding relationship between the impedance components and every individual semicircle in the Nyquist curves is inferred theoretically and the result is satisfying. Based on the analysis using this model, we conclude that the structural stability of SEI film is increased and the interfacial compatibility between the lithium substrate and the SEI film is improved by 1,3-dioxolane or 1,4-dioxane pretreatment.

  9. A modal impedance technique for mid and high frequency analysis of an uncertain stiffened composite plate

    Science.gov (United States)

    Seçgin, A.; Kara, M.; Ozankan, A.

    2016-03-01

    A modal impedance technique is introduced for mid frequency vibration analyses. The approach is mainly based on statistical energy analysis (SEA), however loss factors are determined by not only driving but also contributed by transfer mobilities. The mobilities are computed by finite element modal analysis. The technique takes geometrical complexity and boundary condition into account to handle their mid-frequency effects. It is applied to a stiffened composite plate having randomized mass, i.e., uncertain plate. For the verification, several numerical and experimental tests are performed. Internal damping of subsystems is evaluated using power injection and is then fed to finite element software to perform numerical analyses. Monte Carlo simulation is employed for the uncertainty analyses. To imitate plate mass heterogeneity, many small masses are used in both numerical and experimental analysis. It is shown that the proposed technique can reliably be used for vibration analyses of uncertain complex structures from mid to high frequency regions.

  10. The inverse problem of bioelectricity: an evaluation

    NARCIS (Netherlands)

    Oosterom, A. van

    2012-01-01

    This invited paper presents a personal view on the current status of the solution to the inverse problem of bioelectricity. Its focus lies on applications in the field of electrocardiography. The topic discussed is also relevant in other medical domains, such as electroencephalography, electroneurog

  11. Solid oxide electrolysis cell analysis by means of electrochemical impedance spectroscopy: A review

    Science.gov (United States)

    Nechache, A.; Cassir, M.; Ringuedé, A.

    2014-07-01

    High temperature water electrolysis based on Solid Oxide Electrolysis Cell (SOEC) is a very promising solution to produce directly pure hydrogen. However, degradation issues occurring during operation still represent a scientific and technological barrier in view of its development at an industrial scale. Electrochemical Impedance Spectroscopy (EIS) is a powerful in-situ fundamental tool adapted to the study of SOEC systems. Hence, after a quick presentation of EIS principle and data analysis methods, this review demonstrates how EIS can be used: (i) to characterize the performance and mechanisms of SOEC electrodes; (ii) as a complementary tool to study SOEC degradation processes for different cell configurations, in addition to post-test tools such as scanning electron microscopy (SEM) or X-ray diffraction (XRD). The use of EIS to establish a systematic SOEC analysis is introduced as well.

  12. Hydration dynamics of collagen/PVA composites: Thermoporometric and impedance analysis

    International Nuclear Information System (INIS)

    Porous scaffolds like collagen/PVA (polyvinyl alcohol) composites have potential applications in the field of biomedical engineering. The pore properties and electrical behavior of collagen/PVA composite system were investigated by thermoporometry technique and electrochemical impedance analysis. The porous composites were crosslinked by less cytotoxic genipin due to the versatility in the crosslinking reactivity between the amino groups. Different physicochemical properties like rheological behavior, thermal stability of the protein and morphological changes of the composites were investigated as a function of PVA concentration by viscosity profile, temperature dependant circular dichroic spectroscopic studies, scanning electron microscopy. Bound water constrained within the pores of collagen/PVA composites seems to provide signatures for changes induced by amount of additives on the pore diameter and distribution in composite molecules. Impedance measurements of the composites in the frequency range of 10−2 to 105 Hz reveal that concentration of the additive and crosslinking significantly influence the permittivity of the composites. The tunable physicochemical properties help to gain insight for regulating cellular events for tissue and organ regeneration. - Highlights: • Additive and crosslinker influence pore size distribution of biocomposite. • Pore sizes are shifted to the lower nanometer range with increasing PVA concentration. • Additives influence reorientation of water near the peptide group of collagen. • Increase of tan δ values with the decrease of frequency indicates that the resistive component of biocomposites dominates

  13. Impedance Analysis of Heat Treated Polyethylene Oxide Polymeric Material for a Neural Storage Application

    Directory of Open Access Journals (Sweden)

    Mahmoud Z. Iskandarani

    2009-01-01

    Full Text Available Problem statement: From the early days of, researchers have developed electronic models of neurons designed to emulate neural behavior with electrical signals that mimic in some ways the measured potentials of biological neurons. Researchers interested in fabricating artificial neurons have long sought a simple and techniques to produce devices that efficiently store synaptic weights, which is behind holding a particular state in relation to conductance parameters. As Engineers become closer to realizing accurate hardware models of neurons, the need for a simple analog memory device grows correspondingly. To determine the storage characteristics of polyethylene oxide based polymer as the base material for high charge storage analogue neural switch. Approach: Various devices prepared under controlled conditions. Each device tested for its impedance characteristics as a function of both frequency and temperature. Mathematical model developed to account for the obtained characteristics. Results: The heat treated devices showed stability, repeatability and ability to store enough charge for long time periods. Impedance analysis proved a similar response to the actual neural switches. Conclusion: The symmetrical behavior for such devices opened a wide application area for the manufacturing of low and high frequency analogue devices for intelligent system applications.

  14. Electrochemical impedance spectroscopy analysis of porous silicon prepared by photo-electrochemical etching: current density effect

    Science.gov (United States)

    Husairi, F. S.; Rouhi, J.; Eswar, K. A.; Zainurul, A. Z.; Rusop, M.; Abdullah, S.

    2014-09-01

    Electrical impedance characteristics of porous silicon nanostructures (PSiNs) in frequency function were studied. PSiNs were prepared through photo-electrochemical etching method at various current densities (15-40 mA/cm2) and constant etching time. The atomic force microscope images of PSiNs show that pore diameter and roughness increase when current density increases to 35 mA/cm2. The surface roughness subsequently decreases because of continuous etching of pillars, and a second etching process occurs. Photoluminescence spectra show blue and red shift with increasing applied current density that is attributed to PSiNs size. Variations of electrical resistance and capacitance values of PSiNs were measured using electrochemical impedance spectroscopy analysis. These results indicate that PSiNs prepared at 20 mA/cm2 current density have uniform porous structures with a large number of pillars. Furthermore, this PSiNs structure influences large values of charge transfer resistance and double layer capacitance, indicating potential application in sensors.

  15. Correlation between percentage of body fat measured by the Slaughter equation and bio impedance analysis technique in Mexican schoolchildren

    Directory of Open Access Journals (Sweden)

    Mariana Orta Duarte

    2014-01-01

    Full Text Available Introduction: Obesity is considered one of the most serious public health problems of the 21st century in children and adolescents. The percentile or Z-score of the body mass index is widely used in children and adolescents to define and assess overweight and obesity, but it does not determine the percentage of total body fat. Other anthropometric measurements that determine total body fat are skinfold thickness and methods of body composition assessment such as bio impedance analysis, both of which are rapid and inexpensive. Objetive: The aim of the study was to correlate the percentage of body fat determined by the Slaughter equation with the percentage of body fat determined by the bio impedance analysis technique, and the body mass index in schoolchildren. Methods: The design of the study is cross-sectional and it was performed on a random selection of 74 children (9.47 ± 1.55 years old attending a primary school in Colima, Mexico during 2011. The percentage of body fat was measured by the Slaughter equation and bio impedance analysis technique. Body mass index was calculated. Inferential statistics were performed with the non-paired Student's t test, Pearson's correlation for quantitative variables (percentage of body fat by the Slaughter equation and bio impedance analysis and the Fisher exact test for qualitative variables. Results: A significant correlation (r = 0.74; p < 0.001 was identified between the percentage of fat measured by the Slaughter equation and bio impedance analysis. We also identified a significant correlation between the percentage of fat measured by the Slaughter equation and body mass index (r = 0. 85; p < 0.001 and the percentage of fat measured by bio impedance analysis and body mass index (r = 0.78; p < 0.001. Conclusion: Given that we identified a significant positive correlation between BIA and STE, we conclude that both are adequate alternatives for measuring the percentage of body fat among schoolchildren in

  16. Impedance spectroscopy analysis of CeNbO4.25

    Institute of Scientific and Technical Information of China (English)

    李琴; 王金玲; 张国光

    2013-01-01

    Monoclinic CeNbO4.25 was prepared by solid state reaction. Complex impedance analysis indicated the presence of grain interior effect along with the grain boundary contribution. The values of ionic transference number ti below 423 K were calculated to be about 0.5. The activation energies of ionic conductivity and electronic conductivity were deduced to be 36.0 and 37.2 kJ/mol, re-spectively. The real part of the AC conductivity was frequency dependent. At high frequencies corresponding to the grain interior ef-fect, the non-Debye nature of the AC conductivity was interpreted by the correlated hopping of interstitial oxygen with the electron holes on the basis of the correlated barrier hopping (CBH) model.

  17. Impedance analysis of Pb2Sb3LaTi5O18 ceramic

    Indian Academy of Sciences (India)

    C K Suman; K Prasad; R N P Choudhary

    2004-12-01

    Polycrystalline sample of Pb2Sb3LaTi5O18, a member of tungsten–bronze (TB) family, was prepared using a high temperature solid-state reaction technique. XRD analysis indicated the formation of a singlephase orthorhombic structure. The dielectric studies revealed the diffuse phase transition and the transition temperature was found to be at 52°C. Impedance plots were used as tools to analyse the sample behaviour as a function of frequency. Cole–Cole plots showed Debye relaxation. The activation energy was estimated to be 0.634 eV from the temperature variation of d.c. conductivity. The nature of variation of d.c. conductivity with temperature suggested NTCR behaviour.

  18. Electrochemical impedance spectroscopy of supercapacitors: A novel analysis approach using evolutionary programming

    Science.gov (United States)

    Oz, Alon; Hershkovitz, Shany; Tsur, Yoed

    2014-11-01

    In this contribution we present a novel approach to analyze impedance spectroscopy measurements of supercapacitors. Transforming the impedance data into frequency-dependent capacitance allows us to use Impedance Spectroscopy Genetic Programming (ISGP) in order to find the distribution function of relaxation times (DFRT) of the processes taking place in the tested device. Synthetic data was generated in order to demonstrate this technique and a model for supercapacitor ageing process has been obtained.

  19. Numerical analysis of complex impedance and microwave absorption of metamaterials composed of split cut wires on grounded dielectric substrate

    Science.gov (United States)

    Lim, Jun-Hee; Liu, Tian; Kim, Sung-Soo

    2014-06-01

    The microwave absorption of metamaterials composed of split cut wire (SCW) on grounded dielectric substrate has been investigated on the basis of equivalent transmission line circuit. S-parameters (S 11 and S 21) and input impedance are numerically simulated with variations of the thickness and dielectric loss of the substrate and the geometry of the SCW. Magnetic resonance resulting from antiparallel currents between SCW and ground plane was observed at the frequency of minimum reflection loss. The simulated resonance frequency and reflection loss can be explained well on the basis of the circuit theory of an LC resonator. Analysis of the input impedance of the high impedance surface has shown that perfect absorption can be obtained at the optimized impedance-matching condition, which is dependent on SCW width, thickness and the dielectric loss of the substrate. Better insight into the absorption mechanism of metamaterial absorbers can be attained through the parametric analysis on complex impedance of SCW and its relationship with reflection loss.

  20. Bioelectric Applications for Treatment of Melanoma

    International Nuclear Information System (INIS)

    Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma

  1. Bioelectric Applications for Treatment of Melanoma

    Directory of Open Access Journals (Sweden)

    Richard Heller

    2010-09-01

    Full Text Available Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs. EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.

  2. Bioelectric Applications for Treatment of Melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Beebe, Stephen J., E-mail: sbeebe@odu.edu; Schoenbach, Karl H.; Heller, Richard [Frank Reidy Research Center for Bioelectrics/Old Dominion University 4211 Monarch Way, Suite 300, Norfolk, Virginia 23508 (United States)

    2010-09-27

    Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.

  3. Density-viscosity product of small-volume ionic liquid samples using quartz crystal impedance analysis.

    Science.gov (United States)

    McHale, Glen; Hardacre, Chris; Ge, Rile; Doy, Nicola; Allen, Ray W K; MacInnes, Jordan M; Bown, Mark R; Newton, Michael I

    2008-08-01

    Quartz crystal impedance analysis has been developed as a technique to assess whether room-temperature ionic liquids are Newtonian fluids and as a small-volume method for determining the values of their viscosity-density product, rho eta. Changes in the impedance spectrum of a 5-MHz fundamental frequency quartz crystal induced by a water-miscible room-temperature ionic liquid, 1-butyl-3-methylimiclazolium trifluoromethylsulfonate ([C4mim][OTf]), were measured. From coupled frequency shift and bandwidth changes as the concentration was varied from 0 to 100% ionic liquid, it was determined that this liquid provided a Newtonian response. A second water-immiscible ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C4mim][NTf2], with concentration varied using methanol, was tested and also found to provide a Newtonian response. In both cases, the values of the square root of the viscosity-density product deduced from the small-volume quartz crystal technique were consistent with those measured using a viscometer and density meter. The third harmonic of the crystal was found to provide the closest agreement between the two measurement methods; the pure ionic liquids had the largest difference of approximately 10%. In addition, 18 pure ionic liquids were tested, and for 11 of these, good-quality frequency shift and bandwidth data were obtained; these 12 all had a Newtonian response. The frequency shift of the third harmonic was found to vary linearly with square root of viscosity-density product of the pure ionic liquids up to a value of square root(rho eta) approximately 18 kg m(-2) s(-1/2), but with a slope 10% smaller than that predicted by the Kanazawa and Gordon equation. It is envisaged that the quartz crystal technique could be used in a high-throughput microfluidic system for characterizing ionic liquids.

  4. An introduction to the memristor - a valuable circuit element in bioelectricity and bioimpedance

    Directory of Open Access Journals (Sweden)

    Gorm Krogh Johnsen

    2012-08-01

    Full Text Available The memristor (short for memory resistor is a yet quite unknown circuit element, though equally fundamental as resistors, capacitors, and coils. It was predicted from theory arguments nearly 40 years ago, but not realized as a physical component until recently. The memristor shows many interesting features when describing electrical phenomena, especially at small (molecular or cellular scales and can in particular be useful for bioimpedance and bioelectricity modeling. It can also give us a richer and much improved conceptual understanding of many such phenomena. Up until today the tools available for circuit modeling have been restricted to the three circuit elements (RLC as well as the widely used constant phase element (CPE. However, as one element has been missing in our modeling toolbox, many bioelectrical phenomena may have been described incompletely as they are indeed memristive. Such memristive behavior is not possible to capture within a traditional RLC framework. In this paper we will introduce the memristor and look at potential bioelectrical memristive phenomena. The goal is to explain the new memristor’s properties in a simple manner as well as to highlight its importance and relevance. We conclude that memristors must be included as a readily used building block for bioimpedance and bioelectrical data analysis and modeling.

  5. Impedance Analysis of the Conditioning of PBI–Based Electrode Membrane Assemblies for High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Vang, Jakob Rabjerg; Andreasen, Søren Juhl;

    2013-01-01

    This work analyses the conditioning of single fuel cell assemblies based on different membrane electrode assembly (MEA) types, produced by different methods. The analysis was done by means of electrochemical impedance spectroscopy, and the changes in the fitted resistances of the all the tested...

  6. Combined Dielectrophoresis and Impedance Systems for Bacteria Analysis in Microfluidic On-Chip Platforms.

    Science.gov (United States)

    Páez-Avilés, Cristina; Juanola-Feliu, Esteve; Punter-Villagrasa, Jaime; Del Moral Zamora, Beatriz; Homs-Corbera, Antoni; Colomer-Farrarons, Jordi; Miribel-Català, Pere Lluís; Samitier, Josep

    2016-09-16

    Bacteria concentration and detection is time-consuming in regular microbiology procedures aimed to facilitate the detection and analysis of these cells at very low concentrations. Traditional methods are effective but often require several days to complete. This scenario results in low bioanalytical and diagnostic methodologies with associated increased costs and complexity. In recent years, the exploitation of the intrinsic electrical properties of cells has emerged as an appealing alternative approach for concentrating and detecting bacteria. The combination of dielectrophoresis (DEP) and impedance analysis (IA) in microfluidic on-chip platforms could be key to develop rapid, accurate, portable, simple-to-use and cost-effective microfluidic devices with a promising impact in medicine, public health, agricultural, food control and environmental areas. The present document reviews recent DEP and IA combined approaches and the latest relevant improvements focusing on bacteria concentration and detection, including selectivity, sensitivity, detection time, and conductivity variation enhancements. Furthermore, this review analyses future trends and challenges which need to be addressed in order to successfully commercialize these platforms resulting in an adequate social return of public-funded investments.

  7. Combined Dielectrophoresis and Impedance Systems for Bacteria Analysis in Microfluidic On-Chip Platforms.

    Science.gov (United States)

    Páez-Avilés, Cristina; Juanola-Feliu, Esteve; Punter-Villagrasa, Jaime; Del Moral Zamora, Beatriz; Homs-Corbera, Antoni; Colomer-Farrarons, Jordi; Miribel-Català, Pere Lluís; Samitier, Josep

    2016-01-01

    Bacteria concentration and detection is time-consuming in regular microbiology procedures aimed to facilitate the detection and analysis of these cells at very low concentrations. Traditional methods are effective but often require several days to complete. This scenario results in low bioanalytical and diagnostic methodologies with associated increased costs and complexity. In recent years, the exploitation of the intrinsic electrical properties of cells has emerged as an appealing alternative approach for concentrating and detecting bacteria. The combination of dielectrophoresis (DEP) and impedance analysis (IA) in microfluidic on-chip platforms could be key to develop rapid, accurate, portable, simple-to-use and cost-effective microfluidic devices with a promising impact in medicine, public health, agricultural, food control and environmental areas. The present document reviews recent DEP and IA combined approaches and the latest relevant improvements focusing on bacteria concentration and detection, including selectivity, sensitivity, detection time, and conductivity variation enhancements. Furthermore, this review analyses future trends and challenges which need to be addressed in order to successfully commercialize these platforms resulting in an adequate social return of public-funded investments. PMID:27649201

  8. Frequency Synchronization Analysis in Digital lock-in Methods for Bio-impedance Determination

    OpenAIRE

    Brajkovič Robert; Žagar Tomaž; Križaj Dejan

    2014-01-01

    The lock-in method is one of the most frequently used methods for reconstruction of measured signals and as such frequently applied in the (bio)impedance method to determine the modulus and phase of the (bio)impedance. In implementation of the method in a (bio)impedance measurement device one has to consider possible non synchronized frequencies of the reference and the analyzed signals as well as potential sources of noise. In this work we analyzed these errors theoretically and experimental...

  9. Microelectrode and Impedance Analysis of Anion Secretion in Calu-3 Cells

    Directory of Open Access Journals (Sweden)

    Tamada T

    2001-07-01

    Full Text Available Calu-3 cells secrete HCO(3(- in response to cAMP agonists but can be stimulated to secrete Cl(- with K(+ channel activating agonists. Microelectrode and impedance analysis experiments were performed to obtain a better understanding of the conductances and driving forces involved in these different modes of anion secretion in Calu-3 cells. Microelectrode studies revealed apical and basolateral membrane depolarizations upon the addition of forskolin (V(ap -52 mV vs. -21 mV; V(bl -60 mV vs. -44 mV that paralleled the hyperpolarization of the mucosal negative transepithelial voltage (V(T -8 mV vs. -23 mV. These changes were accompanied by a decrease in the apical membrane fractional resistance (F(Rap from approximately 0.50 to 0.08, consistent with the activation of an apical membrane conductance. The subsequent addition of 1-ethyl-2-benzimidazolinone (1-EBIO, a K(+ channel activator, hyperpolarized V(ap to -27 mV, V(bl to -60 mV and V(T to -33 mV. Impedance analysis revealed the apical membrane resistance (R(ap of the forskolin-stimulated cells was less than 20 ohm cm(2, indeed in most monolayers R(ap fell to less than 5 ohm cm(2. The impedance derived estimate of the basolateral membrane resistance (R(bl was approximately 170 ohm cm(2 in forskolin treated cells and fell to 50 ohm cm(2 with the addition of 1-EBIO. Using these values for the R(bl and the F(Rap value of 0.08 yields a R(ap of approximately 14 ohm cm(2 in the presence of forskolin and 4 ohm cm(2 in the presence of forskolin plus 1-EBIO. Thus, by two independent methods, forskolin-stimulated Calu-3 cells are seen to have a very high apical membrane conductance of 50 to 200 mS/cm(2. Therefore, we would assert that even at one-tenth the anion selectivity for Cl(-, this high conductance could support the conductive exit of HCO(3(- across the apical membrane. We further propose that this high apical membrane conductance serves to clamp the apical membrane potential near the equilibrium

  10. Electrochemical impedance analysis of nanoporous TiO2 electrode at low bias potential

    Institute of Scientific and Technical Information of China (English)

    Sheng Jun Li; Yuan Lin; Zeng Chen; Jing Bo Zhang; Xiao Wen Zhou

    2010-01-01

    TiO2 colloid was prepared by the sol-gel method and was bladed on transparent conduction glass to made nanoporous electrode.The impedance performance of TiO2 electrode was studied at various bias potential.A simplified equivalent circuit was proposed to investigate the charge transport impedance of TiO2 film and good fitting results were obtained.

  11. Primary report of noninvasive impedance monitoring of cerebral hematoma and edema in patients with intracerebral hemorrhage

    Institute of Scientific and Technical Information of China (English)

    Xia Yi Lu; Dong Wei-Wei; Yang Hao; Long Men; Yang Hua

    2000-01-01

    Background and Objective Brain edema is one of the most important clinical process in many diseases. Tissue impedance monitoring offers a non-invasive, bedside, rapid, and reliable technique for the monitoring of the brain edema. Methods We use a bioelectrical impedance(BEI) monitoring unit to record the brain impedance in the healthy volunteer and the patients with intracerebral hemorrhage. Percent of BEI variations were calculation. Results and Conclusions Brain BEI haven f any difference between both hemispheres in normal ones. In 48hrs, BEI value at hematoma-side was obviously decreased; after 48hrs, BEI value was obviously increased and continue to tenth day. Brain bioelectrical impedance monitoring, particularly noninvasively, is a first time in this field. The primary results show brain BEI could reflect the evolution of cerebral hematoma and edema.

  12. Electrode impedance analysis of chronic tungsten microwire neural implants: understanding abiotic vs. biotic contributions

    Directory of Open Access Journals (Sweden)

    Viswanath eSankar

    2014-05-01

    Full Text Available Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially.

  13. Bioelectrical homeostasis as a component of acupuncture mechanism.

    Science.gov (United States)

    Zukauskas, G; Dapsys, K

    1991-01-01

    Low frequency electrical current and super-high frequency electromagnetic field were applied to acupuncture points of stomach meridian in dogs. The stimulation effect on Bioelectrical potentials of 5 acupuncture points of stomach, spleen, liver, kidney, small intestine meridians and non-acupuncture skin zones was studied in conditions of blocked autonomic ganglia or neuro-muscular junctions of the dog. The influence of ganglioblockading and myorelaxating drugs on Bioelectrical potentials of acupuncture points was also researched. The results are discussed from the neurohumoural and bioelectrical hypotheses points of view. The conclusion that both mechanisms of acupuncture supplement each other is drawn. The principle of bioelectrical homeostasis as a component of acupuncture mechanism is proposed. Bioelectrical homeostasis along with other kinds of homeostasis forms a system of first level homeostats which is united into second level homeostat by the autonomic nervous system. PMID:1685620

  14. Relating cyclic voltammetry and impedance analysis in a viologen electrochromic device

    Energy Technology Data Exchange (ETDEWEB)

    Vergaz, Ricardo; Barrios, David; Sanchez-Pena, Jose-Manuel [Grupo de Displays y Aplicaciones Fotonicas, Department Tecnologia Electronica, Universidad Carlos III de Madrid, C/Butarque, 15, E28911 Leganes, Madrid (Spain); Pozo-Gonzalo, Cristina; Salsamendi, Maitane [Centre for Electrochemical Technologies (CIDETEC), Dept. Nuevos Materiales, Parque Tecnologico de San Sebastian - Paseo Miramon, 196, E-20009, San Sebastian (Spain)

    2009-12-15

    Viologens are electrochromic materials that have a wide range of coloration depending on the radical substituents. The results for a new blue viologen-based device, that has recently been patented, with an active area of 8.5 cm{sup 2} is presented in this paper. The characterization techniques used are based on optical measurements, chronoamperometry, cyclic voltammetry, and impedance spectroscopy analysis. A study of the results obtained from these measurements provides both an overview of the reactions taking place and has allowed an equivalent circuit to be developed which relates the different electrochemical parameters. The transmittance is observed to change from 80% to 15% in 600 nm for input voltages ranging from 0 to 2.5 V. However, increasing voltage beyond 1.8 V shows no optical change, thus, maintaining the voltage below this level optimizes the use of electrical current. Voltages and charges used for each redox reaction have been computed and are seen to be linearly related. The equivalent circuit generated to mimic the process has included parameters based on Warburg diffusion and double-layer capacitances. Results from this model are consistent with measurements for up to 1.8 V. Saturation of reduced species has been deduced for input voltages beyond this level. (author)

  15. [Some problems related to the automatic interpretation of recordings of bioelectric activity in man].

    Science.gov (United States)

    Gaillard, J M

    1975-05-01

    The automatic interpretation of recordings of bioelectric activities in man represents a certain number of difficulties which are discussed more specially insofar as the analysis of automatic polygraphic recordings of sleep. A system of analysis specifically utilising "passe bande" filters has been used to obtain interesting results on many recordings. The interpretation itself is obtained with the help of a small computer coupled to a system of measurement and digitalisation. PMID:1220526

  16. Bioelectricity potential in Mato Grosso do Sul, Brazil; O potencial de bioeletricidade no Mato Grosso do Sul

    Energy Technology Data Exchange (ETDEWEB)

    Turdera, Eduardo Mirko Valenzuela [Universidade Federal da Grande Dourados (UFGD), Dourados, MS (Brazil). Faculdade de Ciencias Exatas e Tecnologicas], E-mail: eduardoturdera@ufgd.edu.br

    2009-07-01

    This paper presents the importance of bioelectricity power from renewable source in the power output of Mato Grosso do Sul (MS). The power energy capacity of MS could grow the next years due arrived of more of the thirty mills on medium term. This scenario will be very favorable because MS State will have conditions to meet power domestic market demand and to have significant surplus of electricity to export. Sugar cane crops are expanding and they could propitiate combined heat power (CHP or cogeneration) technology growth, we make an analysis about the share of the bioelectricity availability in MS power capacity installed. Bioelectricity could be good to MS as well as energy and economic aspects. (author)

  17. Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Tobias; Weinmueller, Christian; Nabavi, Majid; Poulikakos, Dimos [Department of Mechanical and Process Engineering, Laboratory of Thermodynamics in Emerging Technologies, Institute of Energy Technology, ETH Zurich, CH-8092 Zurich (Switzerland)

    2010-11-15

    A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels. (author)

  18. Design and evaluation of area-efficient and wide-range impedance analysis circuit for multichannel high-quality brain signal recording system

    Science.gov (United States)

    Iwagami, Takuma; Tani, Takaharu; Ito, Keita; Nishino, Satoru; Harashima, Takuya; Kino, Hisashi; Kiyoyama, Koji; Tanaka, Tetsu

    2016-04-01

    To enable chronic and stable neural recording, we have been developing an implantable multichannel neural recording system with impedance analysis functions. One of the important things for high-quality neural signal recording is to maintain well interfaces between recording electrodes and tissues. We have proposed an impedance analysis circuit with a very small circuit area, which is implemented in a multichannel neural recording and stimulating system. In this paper, we focused on the design of an impedance analysis circuit configuration and the evaluation of a minimal voltage measurement unit. The proposed circuit has a very small circuit area of 0.23 mm2 designed with 0.18 µm CMOS technology and can measure interface impedances between recording electrodes and tissues in ultrawide ranges from 100 Ω to 10 MΩ. In addition, we also successfully acquired interface impedances using the proposed circuit in agarose gel experiments.

  19. Interrelationship of the muscle mass and muscle strength of students in late puberty and speed of sound detected by quantitative ultrasound method and bioelectrical impedance method%定量超声法和生物电阻抗法测定青春发育后期学生肌肉量、肌力与跟骨超声传导速度的相互关系

    Institute of Scientific and Technical Information of China (English)

    李成明; 张伟

    2012-01-01

    BACKGROUND: Studies addressing the relation of student's body composition and bone mineral density in late puberty are rare. OBJECTIVE: To explore the relationship of physical fitness and body composition of students in the late youth with the speed of sound (SOS). METHODS: Quantitative ultrasound and bio-electrical impedance methods were applied in 1 004 students aged 17-20 years. RESULTS AND CONCLUSION: The physique and body composition of body students were significantly better than those of girl students. Students with different degrees of obesity had obvious physical changes: the higher the fat percentage, the worse the physical fitness. Fat percentage, muscle mass and muscle strength had a significant linear relationship with the SOS. These findings show that a clear gender difference exists between the physical fitness and body composition, but there is no gender difference in the SOS; students with different degrees of obesity has obvious physical differences, and the fat percentage in the normal range indicates the good physical fitness of students; the fat percentage is negatively correlated to the SOS, and the higher the fat percentage, the lower the bone mineral density that is influenced by muscle strength and muscle mass.%背景:查阅国内外研究文献发现研究青春发育后期学生体成分与骨密度的文章很少.目的:探讨处于青春后期的学生体质、体成分与跟骨超声传导速度的相互关系.方法:采用定量超声法和生物电阻抗法对在校的1 004名17~20周岁的学生进行了测试.结果与结论:男生的体质和体成分明显好于女生;肥胖度不同的学生,体质具有明显的层次变化,脂肪百分比越高则体质越差;脂肪百分比、肌肉量和肌力与跟骨超声传导速度具有显著的线性关系.结果可见体质和体成分具有明显的性别差异,但跟骨超声传导速度没有性别差异;肥胖度不同的学生体质具有明显的差异性,脂肪百分比处在

  20. An Analysis of Electrical Impedance Measurements Applied for Plant N Status Estimation in Lettuce (Lactuca sativa

    Directory of Open Access Journals (Sweden)

    Rafael F. Muñoz-Huerta

    2014-06-01

    Full Text Available Nitrogen plays a key role in crop yields. Hence, farmers may apply excessive N fertilizers to crop fields, inducing environmental pollution. Crop N monitoring methods have been developed to improve N fertilizer management, most of them based on leaf or canopy optical-property measurements. However, sensitivity to environmental interference remains an important drawback. Electrical impedance has been applied to determine the physiological and nutritional status of plant tissue, but no studies related to plant-N contents are reported. The objective of this article is to analyze how the electrical impedance response of plants is affected by their N status. Four sets of lettuce (Lactuca sativa L. with a different N-source concentrations per set were used. Total nitrogen and electrical impedance spectra (in a 1 to 100 kHz frequency range were measured five times per set, three times every other day. Minimum phase angles of impedance spectra were detected and analyzed, together with the frequency value in which they occurred, and their magnitude at that frequency. High and positive correlation was observed between plant N content and frequency values at minimum phase angle with no significant variations detected between days of measurement. These results suggest that electrical impedance can be sensitive to plant N status.

  1. ANALYSIS OF DYNAMIC INSTABILITY OF INTERFACIAL SLIP WAVES BASED ON THE SURFACE IMPEDANCE TENSOR

    Institute of Scientific and Technical Information of China (English)

    李楠; 汪越胜; 于桂兰

    2004-01-01

    A new method relying on the Stroh formulism and the theory of the surface impedance tensor was developed to investigate the dynamic instability of interfacial slip waves.The concept of the surface impedance tensor was extended to the case where the wave speed is of a complex value,and the boundary conditions at the frictionally contacting interface were expressed by the surface impedance tensor.Then the boundary value problem was transformed to searching for zeroes of a complex polynomial in the unit circle.As an example,the steady frictional sliding of an elastic half-space in contact with a rigid flat surface was considered in details.A quartic complex characteristic equation was derived and its solution behavior in the unit circle was discussed.An explicit expression for the instability condition of the interfacial slip waves was presented.

  2. Analysis of the longitudinal space charge impedance of a round uniform beam inside parallel plates and rectangular chamber

    CERN Document Server

    Wang, Lanfa

    2014-01-01

    This paper analyses the longitudinal space charge (LSC) impedances of a round uniform beam inside a rectangular and parallel plate chamber using image charge method. The analysis is valid for arbitrary wavelengths and the calculation converges fast. The research shows that only a few of image beams are needed to get a relative error less than 0.1%. The beam offset effect is also included.

  3. Correlation between percentage of body fat measured by the Slaughter equation and bio impedance analysis technique in Mexican schoolchildren

    OpenAIRE

    Mariana Orta Duarte; Yunue Flores Ruelas; Fátima López-Alcaraz; Mario del Toro-Equihua; Carmen Alicia Sánchez-Ramírez

    2014-01-01

    Introduction: Obesity is considered one of the most serious public health problems of the 21st century in children and adolescents. The percentile or Z-score of the body mass index is widely used in children and adolescents to define and assess overweight and obesity, but it does not determine the percentage of total body fat. Other anthropometric measurements that determine total body fat are skinfold thickness and methods of body composition assessment such as bio impedance analysis, both o...

  4. Quantitative analysis of effective height of probes in microwave impedance microscopy

    Science.gov (United States)

    Wei, Zhun; Ma, Eric Yue; Cui, Yong-Tao; Johnston, Scott; Yang, Yongliang; Agarwal, Krishna; Kelly, Michael A.; Shen, Zhi-Xun; Chen, Xudong

    2016-09-01

    A quantitative approach is used to determine an effective height of probe beyond which the capacitance contribution is not significant in microwave impedance microscopy (MIM). We compare the effective height for three different modes of measurement, i.e., capacitance C(l) (l is the tip-sample distance), derivative of capacitance (C'(l)), and second derivative of capacitance (C″(l)). We discuss the effects of tip geometry and sample properties such as relative permittivity and sample height on the effective height with examples and analyze the implication on the spatial resolution of MIM. Finally, our results are verified by microwave impedance microscopy (MIM) measurement.

  5. Electrochemical Impedance Analysis of β-TITANIUM Alloys as Implants in Ringers Lactate Solution

    Science.gov (United States)

    Bhola, Rahul; Bhola, Shaily M.; Mishra, Brajendra; Olson, David L.

    2010-02-01

    Commercially pure titanium and two β-titanium alloys, TNZT and TMZF, have been characterized using various electrochemical techniques for their corrosion behavior in Ringers lactate solution. The variation of corrosion potential and solution pH with time has been discussed. Electrochemical Impedance Spectroscopy has been used to fit the results into a circuit model. The stability of the oxides formed on the surface of these alloys has been correlated with impedance phase angles. Cyclic Potentiodynamic Polarization has been used to compute the corrosion parameters for the alloys. TMZF is found to be a better β-alloy as compared to TNZT.

  6. Biohydrogen, bioelectricity and bioalcohols from cellulosic materials

    Energy Technology Data Exchange (ETDEWEB)

    Nissila, M.

    2013-03-01

    The demand for renewable energy is increasing due to increasing energy demand and global warming associated with increasing use of fossil fuels. Renewable energy can be derived from biological production of energy carriers from cellulosic biomass. These biochemical processes include biomass fermentation to hydrogen, methane and alcohols, and bioelectricity production in microbial fuel cells (MFCs). The objective of this study was to investigate the production of different energy carriers (hydrogen, methane, ethanol, butanol, bioelectricity) through biochemical processes. Hydrogen production potential of a hot spring enrichment culture from different sugars was determined, and hydrogen was produced continuously from xylose. Cellulolytic and hydrogenic cultures were enriched on cellulose, cellulosic pulp materials, and on silage at different process conditions. The enrichment cultures were further characterized. The effect of acid pretreatment on hydrogen production from pulp materials was studied and compared to direct pulp fermentation to hydrogen. Electricity and alcohol(s) were simultaneously produced from xylose in MFCs and the exoelectrogenic and alcohologenic enrichment cultures were characterized. In the end, the energy yields obtained from different biochemical processes were determined and compared. In this study, cultures carrying out simultaneous cellulose hydrolysis and hydrogen fermentation were enriched from different sources at different operational conditions. These cultures were successfully utilized for cellulose to hydrogen fermentation in batch systems. Based on these results further research should be conducted on continuous hydrogen production from cellulosic materials.

  7. Application of the Method of Auxiliary Sources for the Analysis of Electromagnetic Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  8. Analysis of diffraction of a plane wave on a grating consisting of impedance bodies of revolution

    International Nuclear Information System (INIS)

    The problem of wave scattering by a grating consisting of coaxial impedance bodies of revolution is solved. The efficient numerical algorithm based on the modified null field method is offered. The method is applied both to scalar and vector formulations of the problem. The numerical results are obtained for various geometries of the grating elements.

  9. Models of intracellular mechanisms of plant bioelectrical potentials caused by combined stimulation

    Directory of Open Access Journals (Sweden)

    D. V. Chernetchenko

    2014-10-01

    Full Text Available This paper deals with bioelectrical potentials of the plants recorded during different types of stimuli and combined stimulus as well. All registrations were observed on the leaves of the corn. We used different stimuli, such as cold, heat, photo- and electrical stimulation, and certain combination of this stimuli. Hardware and software system for automated recording of bioelectrical potentials has been successfully used in this work. We proposed the universal pattern of bioelectrical potentials’ recording which allowed to detect the response of the biological object to different stimuli and various combinations of these stimuli. This pattern can be used for the deeper understanding of biological mechanisms of electrical potentials’ generation in cells and discovering of processes of accommodation of whole organisms to these stimuli. Integrated system of recording and biometrical processing was used for analysis of corn leaves electrical responses to the thermal stimuli. The dynamics of these potentials was studied, with the quantitative analysis of the potential level stabilization.We calculated the ratio of amplitude of response potentials to the first response amplitude. Mathematical models of the plant cell were used for studying of intracellular mechanisms of biopotentials gereration. As a result of modeling, we revealed that electrical response of the cells was based on selectiveconductivity of cell membrane for Н+ and Ca2+ ions. Therefore, we showed the biophysical relation of plant potentials to underlying intracellular biophysical mechanisms during thermal and combined stimulation.

  10. Impedance spectroscopy of unetched CdTe/CdS solar cells—equivalent circuit analysis

    Science.gov (United States)

    Proskuryakov, Y. Y.; Durose, K.; Taele, B. M.; Oelting, S.

    2007-07-01

    A detailed study of electric and structural properties has been carried out on CdTe/CdS solar cells which deliberately were not subjected to etching by a nitric-phosphoric (NP) or bromine-methanol (Br-Me) acids, conventionally employed for the formation of Te-rich layer before back contacting. In the previous work [J. Appl. Phys. 101, 014505 (2007)] we have shown that cells that were not etched provide more extensive information on sample/material properties than the etched ones, as analyzed by admittance spectroscopy. Although seemingly being able to describe the distribution of defect energy levels, the admittance spectroscopy approach has a significant drawback because the underlying theoretical formulation does not take into account the frequency-dependent contribution from the back contact together with its influence on the trap contributions. In this work we use an alternative methodology for analysis of impedance data measured in dark conditions, which applies an equivalent circuit model to the experimental spectra. In particular, a complete model consisting of 10-12 elements is suggested, which describes all the sets of data taken at different temperatures, unambiguously separating the respective roles of p-n junction parameters, defect trap levels, back contact, as well as spatial inhomogeneities within the cell. It is essential that the values of the parameters used to describe ac response from trap levels and that from the back contact are found to be consistent with admittance and I-V measurements. In addition, the temperature dependence of the dark conductance (GJ) and capacitance (CJ) of the main p-n junction, as well as temperature dependence of back contact resistance (RB), were obtained and analyzed. It was found that GJ(T ) follows exp(T /T0) behavior which is characteristic of temperature-assisted tunneling, while CJ(T) agrees well with values of the high-frequency capacitance of the cell CHF(T). The T dependence of RB is found to follow

  11. Synthetic electrophysiology: optically controlled oscillators in an engineered bioelectric tissue

    Science.gov (United States)

    McNamara, Harold; Zhang, Hongkang; Werley, Christopher; Cohen, Adam

    Multicellular electrical dynamics underlie crucial physiological functions, but the complexity of natural bioelectricity can obscure the relation of individual components (proteins, cells) to emergent system-level dynamics. Here we introduce optopatch-spiking HEK(OS-HEK) tissue, a minimal synthetic bioelectric tissue with 4 transgenic components that supports optical initiation of propagating electrical waves as well direct optical voltage readout. In conjunction with a home-built inverted microscope capable of patterned illumination, we use this tissue to probe the biophysical attributes of this excitable bioelectric medium, including dispersion relations, curvature-dependent wavefront propagation, electrotonic coupling, and effects of boundaries. We then used chemical patterning to define cellular circuits that support controllable oscillations and which retain memory for more than 2 hours (corresponding to 104 oscillations), constituting a substrate for binary bioelectric data storage. Finally, we use optical patterning of boundary conditions in a physically homogeneous tissue to design dynamically reconfigurable oscillators.

  12. Performance analysis and SOH (state of health) evaluation of lithium polymer batteries through electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Electrochemical energy storage has become important in the last years to improve the energetic efficiency of stationary and hybrid energy production systems. Lithium batteries represent the best choice, since they have high energy and power density, high number of cycles and a good temperature behaviour compared to other technologies. It becomes important the monitoring of the state of the battery to know online the energy content, to avoid dangerous operating conditions and to extend the useful life. In this work, we have defined a test procedure to study the ageing of LiPO (lithium polymer) batteries through the EIS (electrochemical impedance spectroscopy) technique. Through a fitting procedure performed on the acquired IS (impedance spectra), we have extracted the parameters of an equivalent circuit model to reproduce the voltage discharge curves of the batteries and to study the performance under load. Then we have introduced a relation between the ohmic resistance of the battery and the available capacity to evaluate the SOH (state of health) through the ToE (Theory of Evidence). The method is able to detect the SOH of the tested batteries with a maximum error of 3.73%, with an enhancement to 8.66% when an anomalous cell is considered. - Highlights: • We collected impedance spectra of LiPO cells to determine the SOH with EIS. • A model extracts the physical parameters of the cells from impedance spectra. • The parameters are used to study the performance under load of the cells. • The trend of the ohmic resistance versus capacity is used to build a diagnostic map. • The map has been interpreted by Theory of Evidence to determine the SOH

  13. LOCAL IN-SITU ANALYSIS OF PEM FUEL CELLS BY IMPEDANCE SPECTROSCOPY AND RAMAN MEASUREMENTS

    OpenAIRE

    Gülzow, Erich; Schulze, Mathias; Friedrich, Andreas; Fischer, Peter; Bettermann, Hans

    2011-01-01

    An understanding of the processes inside of low temperature fuel cells on a local scale is required for an effective improvement strategy. For this purpose in situ Raman spectroscopy and local impedance spectroscopy is being developed. The contribution describes the modifications to the cell, and installations of additional devices and the experimental detection systems for integrating both methods into a single cell set up. First results to verify the combined results were carried out and ar...

  14. Analysis of degradation mechanisms in donor-acceptor copolymer based organic photovoltaic devices using impedance spectroscopy

    Science.gov (United States)

    Srivastava, S. B.; Sonar, P.; Singh, S. P.

    2016-09-01

    The stability of organic photovoltaic (OPV) devices in ambient conditions has been a serious issue which needs to be addressed and resolved timely. In order to probe the degradation mechanism in a donor-acceptor polymer PDPP-TNT: PC71BM bulk heterojunction based OPV devices, we have studied current density-voltage (J-V) behavior and impedance spectroscopy of fresh and aged devices. The current-voltage characteristic of optimized fresh devices exhibit a short circuit current density (J sc) of 8.9 mA cm-2, open circuit voltage (V oc) of 0.79 V, fill factor (FF) of 54.6%, and power conversion efficiency (PCE) of 3.8%. For aged devices, J sc, V oc, FF, and PCE were reduced to 57.3%, 89.8%, 44.3% and 23.7% of its initial value, respectively. The impedance spectra measured under illumination for these devices were successfully fitted using a CPE-based circuit model. For aged devices, the low-frequency response in impedance spectra suggests an accumulation of the photo-generated charge carriers at the interfaces which leads to a significant lowering in fill factor. Such degradation in device performance is attributed to the incorporation of oxygen and water molecules in devices. An increase in the recombination resistance indicates a deterioration of free charge carrier generation and conduction in devices.

  15. Diffusion and Gas Conversion Analysis of Solid Oxide Fuel Cells at Loads via AC Impedance

    Directory of Open Access Journals (Sweden)

    Robert U. Payne

    2011-01-01

    Full Text Available Impedance measurements were conducted under practical load conditions in solid oxide fuel cells of differing sizes. For a 2 cm2 button cell, impedance spectra data were separately measured for the anode, cathode, and total cell. Improved equivalent circuit models are proposed and applied to simulate each of measured impedance data. Circuit elements related to the chemical and physical processes have been added to the total-cell model to account for an extra relaxation process in the spectra not measured at either electrode. The processes to which elements are attributed have been deduced by varying cell temperature, load current, and hydrogen concentration. Spectra data were also obtained for a planar stack of five 61 cm2 cells and the individual cells therein, which were fitted to a simplified equivalent circuit model of the total button cell. Similar to the button cell, the planar cells and stack exhibit a pronounced low-frequency relaxation process, which has been attributed to concentration losses, that is, the combined effects of diffusion and gas conversion. The simplified total-cell model approximates well the dynamic behavior of the SOFC cells and the whole stack.

  16. Report of the SSC impedance workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1985-10-28

    This workshop focused attention on the transverse, single-bunch instability and the detailed analysis of the broadband impedance which would drive it. Issues discussed included: (1) single bunch stability -- impact of impedance frequency shape, coupled-mode vs. fast blowup regimes, possible stopband structure; (2) numerical estimates of transverse impedance of inner bellows and sliding contact shielded bellows; (3) analytic estimates of pickup and kicker impedance contributions; and (4) feasibility studies of wire and beam measurements of component impedance.

  17. Brain bioelectrical activity changes in patients with poststroke depression and apathy

    Directory of Open Access Journals (Sweden)

    I. V. Kichuk

    2015-01-01

    Full Text Available Objective: to study the specific features of brain bioelectrical activity in patents with poststroke apathy and depressive disorders.Patients and methods. The investigation enrolled 175 patients (84 men and 91 women with new-onset cerebral stroke at different sites. A total of 107 (61% patients of them were observed to have depressive disorders (n=41 (38% and apathy (n=66 (62% within a year after disease onset. A control group included 68 (39% patients without poststroke affective disorders. The mean age of the study group patients was 66±10 years and that of the control patients was 68±11 years. The severity and magnitude of neurological deficit were evaluated using the U.S. National Institutes of Health Stroke Scale (NIHSS. The patients underwent electroencephalography (EEG, brain computed tomography and magnetic resonance imaging. The investigators used diagnostic and statistical manual of mental disorders (DSM-IV criteria to diagnose depression and the Hamilton depression rating scale (HAM-D and the mini-mental status examination (MMSE to evaluate the mental status. The basic rhythmic power indices in the affected and unaffected hemispheres were calculated, as well as anteroposterior alpha rhythm distribution coefficient and interhemispheric asymmetry coefficient. Results and discussion. The computer EEG analysis was shown to identify the hallmark characteristics of brain bioelectric activity in patients with different types of affective disorders in the acute, early and late recovery periods of stroke. The patients with affective disorders were found to have brain bioelectrical activity changes predominantly in the rapid frequency sub-band on EEG, suggesting midbrain structural dysfunction. In the patients with poststroke depression, depressive disorder scale scores were related to the power of bioelectric activity in the slow and alpha frequency bands manly in the acute stroke period whereas those were correlated with the EEG

  18. An analysis of electrical impedance tomography with applications to Tikhonov regularization

    KAUST Repository

    Jin, Bangti

    2012-01-16

    This paper analyzes the continuum model/complete electrode model in the electrical impedance tomography inverse problem of determining the conductivity parameter from boundary measurements. The continuity and differentiability of the forward operator with respect to the conductivity parameter in L p-norms are proved. These analytical results are applied to several popular regularization formulations, which incorporate a priori information of smoothness/sparsity on the inhomogeneity through Tikhonov regularization, for both linearized and nonlinear models. Some important properties, e.g., existence, stability, consistency and convergence rates, are established. This provides some theoretical justifications of their practical usage. © EDP Sciences, SMAI, 2012.

  19. Study of lithium glassy solid electrolyte/electrode interface by impedance analysis

    Indian Academy of Sciences (India)

    A Karthikeyan; P Vinatier; A Levasseur

    2000-06-01

    Cells of lithium ion conducting glassy electrolyte Li2SO4–Li2O–B2O3 with different combinations of electrodes (stainless steel blocking electrode, lithium non-blocking electrode and TiS2 electrode) have been prepared. The a.c. impedance measurements of the cells have been studied at elevated temperature as a function of time. The circuit elements such as bulk resistance, double layer capacitance and charge transfer resistance have been inferred and their time dependence studied. The results show that the electrolyte and the interface are chemically very stable with the different types of electrodes studied here.

  20. Impedance Analysis of Grain Barrier Potential in SnO2 Gas Sensors①②

    Institute of Scientific and Technical Information of China (English)

    CHENZhong; S.Birlasekaran

    1997-01-01

    The potential barrier(or“grain boundaries”)of SnO2 gas sensor is the dominant factor of conductivity.A new simple method is applied to study the grain boundary using impedance analyzer under different DC bias.A model is presented to explain the experiment results.The model predicts height of the grain boundary under different humidity conditions,as well as grain size.The role of water is discussed.This model can be applied with ease to study the role of other reducing gasses.

  1. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash;

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...... with an example single-switch 400 W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief.......A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance...

  2. Complex Impedance Spectra Analysis of SnO2-glaze Composites

    Institute of Scientific and Technical Information of China (English)

    YAN Dongliang; LU Zhenya; ZHONG Yi; WU Jianqing

    2006-01-01

    SnO2-glaze composites were prepared by Sb-doped SnO2 and SiO2- CaO-Al2 O3- B2 O3 glaze. The composites changed from an electrical insulator to a conductor as the SnO2 content increased from 0wt% to 90 wt% . The complex impedance spectra of the fabricated composites were investigated in the frequency range of 100 Hz-40 MHz and three kinds of typical shape of complex impedance spectra were recorded and analyzed. The spectrum is quite close to the model of conduction via nonohmic contacting when the SnO2 content is relatively low. In high loading region, the spectrum shows the conduction pattern through ohmic contact chains. In the moderate loading region, the model is a mixture of the above two models. Equivalent circuit of the composite changes from resistor-capacitor circuit to resistor-inductor circuit as the content of SnO2 increases.

  3. Exploring Instructive Physiological Signaling with the Bioelectric Tissue Simulation Engine

    Science.gov (United States)

    Pietak, Alexis; Levin, Michael

    2016-01-01

    Bioelectric cell properties have been revealed as powerful targets for modulating stem cell function, regenerative response, developmental patterning, and tumor reprograming. Spatio-temporal distributions of endogenous resting potential, ion flows, and electric fields are influenced not only by the genome and external signals but also by their own intrinsic dynamics. Ion channels and electrical synapses (gap junctions) both determine, and are themselves gated by, cellular resting potential. Thus, the origin and progression of bioelectric patterns in multicellular tissues is complex, which hampers the rational control of voltage distributions for biomedical interventions. To improve understanding of these dynamics and facilitate the development of bioelectric pattern control strategies, we developed the BioElectric Tissue Simulation Engine (BETSE), a finite volume method multiphysics simulator, which predicts bioelectric patterns and their spatio-temporal dynamics by modeling ion channel and gap junction activity and tracking changes to the fundamental property of ion concentration. We validate performance of the simulator by matching experimentally obtained data on membrane permeability, ion concentration and resting potential to simulated values, and by demonstrating the expected outcomes for a range of well-known cases, such as predicting the correct transmembrane voltage changes for perturbation of single cell membrane states and environmental ion concentrations, in addition to the development of realistic transepithelial potentials and bioelectric wounding signals. In silico experiments reveal factors influencing transmembrane potential are significantly different in gap junction-networked cell clusters with tight junctions, and identify non-linear feedback mechanisms capable of generating strong, emergent, cluster-wide resting potential gradients. The BETSE platform will enable a deep understanding of local and long-range bioelectrical dynamics in tissues, and

  4. Exploring Instructive Physiological Signaling with the Bioelectric Tissue Simulation Engine.

    Science.gov (United States)

    Pietak, Alexis; Levin, Michael

    2016-01-01

    Bioelectric cell properties have been revealed as powerful targets for modulating stem cell function, regenerative response, developmental patterning, and tumor reprograming. Spatio-temporal distributions of endogenous resting potential, ion flows, and electric fields are influenced not only by the genome and external signals but also by their own intrinsic dynamics. Ion channels and electrical synapses (gap junctions) both determine, and are themselves gated by, cellular resting potential. Thus, the origin and progression of bioelectric patterns in multicellular tissues is complex, which hampers the rational control of voltage distributions for biomedical interventions. To improve understanding of these dynamics and facilitate the development of bioelectric pattern control strategies, we developed the BioElectric Tissue Simulation Engine (BETSE), a finite volume method multiphysics simulator, which predicts bioelectric patterns and their spatio-temporal dynamics by modeling ion channel and gap junction activity and tracking changes to the fundamental property of ion concentration. We validate performance of the simulator by matching experimentally obtained data on membrane permeability, ion concentration and resting potential to simulated values, and by demonstrating the expected outcomes for a range of well-known cases, such as predicting the correct transmembrane voltage changes for perturbation of single cell membrane states and environmental ion concentrations, in addition to the development of realistic transepithelial potentials and bioelectric wounding signals. In silico experiments reveal factors influencing transmembrane potential are significantly different in gap junction-networked cell clusters with tight junctions, and identify non-linear feedback mechanisms capable of generating strong, emergent, cluster-wide resting potential gradients. The BETSE platform will enable a deep understanding of local and long-range bioelectrical dynamics in tissues, and

  5. Analysis of mobile ionic impurities in polyvinylalcohol thin films by thermal discharge current and dielectric impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    M. Egginger

    2012-12-01

    Full Text Available Polyvinylalcohol (PVA is a water soluble polymer frequently applied in the field of organic electronics for insulating thin film layers. By-products of PVA synthesis are sodium acetate ions which contaminate the polymer material and can impinge on the electronic performance when applied as interlayer dielectrics in thin film transistors. Uncontrollable voltage instabilities and unwanted hysteresis effects are regularly reported with PVA devices. An understanding of these effects require knowledge about the electronic dynamics of the ionic impurities and their influence on the dielectric properties of PVA. Respective data, which are largely unknown, are being presented in this work. Experimental investigations were performed from room temperature to 125°C on drop-cast PVA films of three different quality grades. Data from thermal discharge current (TDC measurements, polarization experiments, and dielectric impedance spectroscopy concurrently show evidence of mobile ionic carriers. Results from TDC measurements indicate the existence of an intrinsic, build-in electric field of pristine PVA films. The field is caused by asymmetric ionic double layer formation at the two different film-interfaces (substrate/PVA and PVA/air. The mobile ions cause strong electrode polarization effects which dominate dielectric impedance spectra. From a quantitative electrode polarization analysis of isothermal impedance spectra temperature dependent values for the concentration, the mobility and conductivity together with characteristic relaxation times of the mobile carriers are given. Also shown are temperature dependent results for the dc-permittivity and the electronic resistivity. The obtained results demonstrate the feasibility to partly remove contaminants from a PVA solution by dialysis cleaning. Such a cleaning procedure reduces the values of ion concentration, conductivity and relaxation frequency.

  6. Impedance spectroscopy analysis on electrical properties of serpentine at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    朱茂旭; 谢鸿森; 郭捷; 许祖鸣; 白武明

    2001-01-01

    The electrical conductivity of serpentine is measured and the microscopic conductance mechanisms are investigated with impedance spectroscopy at 2.5-4.0 GPa and 220-780℃. The results show that the electrical conductivity is strongly dependent on the frequencies used, and that only arcⅠ, which reflects grain interior conductance, occurs and dominates the whole conductance processes over 12-105 Hz at high pressure before dehydration. The arcⅡ, which indicates the grain boundary process, begins to occur at the initial stage of dehydration. After dehydration, due to the presence of highly conductive networks of free water, the electrical conductivity is not depen-dent on frequencies any longer and the total electrical conductivity is dominated by process of ionic conductance of free water in interconnected networks. Dehydration of serpentine enhances pro-nouncedly the total electrical conductivity, through which highly conductive layers (HCL) may be formed in the earth's interior.

  7. Interface electric properties of Si/organic hybrid solar cells using impedance spectroscopy analysis

    Science.gov (United States)

    Wang, Dan; Zhu, Juye; Ding, Li; Gao, Pingqi; Pan, Xiaoyin; Sheng, Jiang; Ye, Jichun

    2016-05-01

    The internal resistance and capacitance of Si/organic hybrid solar cells (Si-HSC) based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) are investigated by electrochemical impedance spectroscopy (EIS). Three types of Nyquist plots in Si-HSC are observed firstly at different bias voltages, while suitable equivalent circuit models are established to evaluate the details of interface carrier transfer and recombination. In particular, the carrier transport property of the PEDOT:PSS film responds at a high frequency (6 × 104-1 × 106 Hz) in three-arc spectra. Therefore, EIS could help us deeply understand the electronic properties of Si-HSC for developing high performance devices.

  8. Fatigue properties and impedance analysis of potassium sodium niobate-strontium titanate transparent ceramics

    Science.gov (United States)

    Liu, Zhiyong; Fan, Huiqing; Lei, Shenhui; Wang, Ju; Tian, Hailin

    2016-10-01

    Highly transparent ferroelectric ceramics based on 0.9K0.5Na0.5NbO3-0.1SrTiO3 were prepared using a pressure-less solid-state sintering method without using hot isostatic pressing and spark plasma sintering. An independence electromechanical response of bipolar switching cycles ( S 33 only degraded 3.2 % up to 107 cycles) was presented in this transparent ceramics, which indicated an extremely stable property under electric field. From impedance spectroscopy and X-ray photoelectron spectroscopy analyses, it was concluded that such optical transparency and fatigue-resistant behaviors were mainly attributed to the lower density of oxygen vacancies in the ceramics.

  9. Energy Dispersive X-Ray and Electrochemical Impedance Spectroscopies for Performance and Corrosion Analysis of PEMWEs

    Science.gov (United States)

    Steen, S. M., Iii; Zhang, F.-Y.

    2014-11-01

    Proton exchange membrane water electrolyzers (PEMWEs) are a promising energy storage technology due to their high efficiency, compact design, and ability to be used in a renewable energy system. Before they are able to make a large commercial impact, there are several hurdles facing the technology today. Two powerful techniques for both in-situ and ex- situ characterizations to improve upon their performance and better understand their corrosion are electrochemical impedance spectroscopy and energy dispersive x-ray spectroscopy, respectively. In this paper, the authors use both methods in order to characterize the anode gas diffusion layer (GDL) in a PEMWE cell and better understand the corrosion that occurs in the oxygen electrode during electrolysis.

  10. Detection of methotrexate in a flow system using electrochemical impedance spectroscopy and multivariate data analysis.

    Science.gov (United States)

    Tesfalidet, Solomon; Geladi, Paul; Shimizu, Kenichi; Lindholm-Sethson, Britta

    2016-03-31

    Methotrexate (MTX), a common pharmaceutical drug in cancer therapy and treatment of rheumatic diseases, is known to cause severe adverse side effects at high dose. As the side effect may be life threatening, there is an urgent need for a continuous, bed-side monitoring of the nominal MTX serum level in a patient while the chemical is being administered. This article describes a detection of MTX using a flow system that consists two modified gold electrodes. Interaction of MTX with the antibodies fixed on the electrode surface is detected by electrochemical impedance spectroscopy and evaluated using singular value decomposition (SVD). The key finding of this work is that the change in the electrode capacitance is found to be quantitative with respect to the concentration of MTX. Moreover a calibration curve constructed using the principal component regression method has a linear range of six orders of magnitude and a detection limit of 1.65 × 10(-10) M.

  11. Analysis of Different Series-Parallel Connection Modules for Dye-Sensitized Solar Cell by Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jung-Chuan Chou

    2016-01-01

    Full Text Available The internal impedances of different dye-sensitized solar cell (DSSC models were analyzed by electrochemical impedance spectrometer (EIS with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the heterojunction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.

  12. Enhanced Shewanella biofilm promotes bioelectricity generation.

    Science.gov (United States)

    Liu, Ting; Yu, Yang-Yang; Deng, Xiao-Peng; Ng, Chun Kiat; Cao, Bin; Wang, Jing-Yuan; Rice, Scott A; Kjelleberg, Staffan; Song, Hao

    2015-10-01

    Electroactive biofilms play essential roles in determining the power output of microbial fuel cells (MFCs). To engineer the electroactive biofilm formation of Shewanella oneidensis MR-1, a model exoelectrogen, we herein heterologously overexpressed a c-di-GMP biosynthesis gene ydeH in S. oneidensis MR-1, constructing a mutant strain in which the expression of ydeH is under the control of IPTG-inducible promoter, and a strain in which ydeH is under the control of a constitutive promoter. Such engineered Shewanella strains had significantly enhanced biofilm formation and bioelectricity generation. The MFCs inoculated with these engineered strains accomplished a maximum power density of 167.6 ± 3.6 mW/m(2) , which was ∼ 2.8 times of that achieved by the wild-type MR-1 (61.0 ± 1.9 mW/m(2) ). In addition, the engineered strains in the bioelectrochemical system at poised potential of 0.2 V vs. saturated calomel electrode (SCE) generated a stable current density of 1100 mA/m(2) , ∼ 3.4 times of that by wild-type MR-1 (320 mA/m(2) ). PMID:25899863

  13. Impedance spectroscopy analysis on electrical properties of serpentine at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    ZHU; Maoxu; (

    2001-01-01

    [1]Stesky, R. M., Brace, W. F., Electrical conductivity of serpentinized rocks to 6 kilobar, J. Geophys. Res., 1973, 78 (32): 7614-7621.[2]Zhu Maoxu, Xie Hongsen, Experimental studies on electrical properties of materials in the earth's interior, Advancement in Geosciences (in Chinese), 1998, 13(5): 438-446.[3]Roberts, J. J., Tyburczy, J. A., Frequency dependent electrical properties of polycrystalline olivine compacts, J. Geophys. Res., 1991, 96 (B10): 16205-16222.[4]Roberts, J. J., Tyburczy, J. A., Frequency dependent electrical properties of minerals and partial-melts, Surv. Geophys., 1994, 15: 239-262.[5]Huebner, I. S., Dillenburg, R. G., Impedance spectra of hot, dry silicate minerals and rock: Qualitative interpretation of spectra, Amer. Mineral, 1995, 80: 46-64.[6]Kavner, A., Li, X-Y, Jeanloz, R., Electrical conductivity of a natural (Mg, Fe)SiO3 majorite garnet, Geophys. Res. Lett., 1995, 22 (22): 3103-3106.[7]Hicks, T. L., Secco, R., Dehydration and decomposition of pyrophyllite at high pressure: Electrical conductivity and X-ray diffraction studies to 5 Gpa, Can. J. Earth Sci., 1997, 34: 875-882.[8]Li, X-Y, Jeanloz, R., Effect of iron content on the electrical conductivity of perovskite and magnesiowustite assemblages at lower mantle condition, J. Geophys. Res., 1991, 96(B4): 6113-6120.[9]Xie Hongsen, Introduction to the Materials in the Earth's Interior (in Chinese), Beijing: Science Press, 1997, 42-53.[10] Tatsurmi, Y., Migration of fluid phase and genesis of basalt magmas in subduction zone, J. Geophys. Res., 1989, 94: 4697-4707.[11] Duba, A., Huenges, G., Nover, E. et al., Impedance of black shale from munsterland 1 borehole: An anomalously good conductor? Geophys. J., 1988, 94: 413-419.[12] Watanabe, T., Kurita, K., The relationship between electrical conductivity and melt fraction in a partially molten simple system: Archies's law behavior, Phys. Earth Planet Inter., 1993, 78: 9-17.[13] Macdonald

  14. Electrochemical impedance analysis of electrodeposited Si-O-C composite thick film on Cu microcones-arrayed current collector for lithium ion battery anode

    Science.gov (United States)

    Hang, Tao; Mukoyama, Daikichi; Nara, Hiroki; Yokoshima, Tokihiko; Momma, Toshiyuki; Li, Ming; Osaka, Tetsuya

    2014-06-01

    The impedance behaviors of Si-O-C composite film electrodeposited on Cu microcones-arrayed current collector have been investigated to understand the electrochemical process kinetics that influences the cycling performance when used as a highly-durable anode in a lithium battery. The impedance was measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge and during several hundred charge-discharge cycles. The measured impedance was interpreted with an equivalent circuit composed of solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance change during discharge, but an abrupt augmentation of diffusive resistance at high depth of discharge is also observed which cannot be explained very well by the presented model. The impedance evolution of this electrode during charge-discharge cycles suggests that the slow growth of the SEI film as well as the increase of the electrode density are responsible for the capacity fading after long term cycling.

  15. Design, analysis and optimization of an electromagnetic actuator for a micro impedance pump

    International Nuclear Information System (INIS)

    This study designs and optimizes an electromagnetic actuator for use in a valveless micro impedance pump. The actuator is modeled to have an electroplated permanent magnet mounted on a flexible PDMS diaphragm and a planar copper micro-coil patterned on a bottom glass substrate. The constituent parts of the actuator, namely the diaphragm, the micro-coil and the magnet, are modeled, analyzed and optimized in such a way as to maximize the actuating force while simultaneously ensuring the mechanical integrity of the device. In performing the analyses, theoretical and mathematical models of the stroke volume and diaphragm deflection are developed based on thin plate theory. The design models are verified theoretically and numerically, and the relationships between the electromagnetic force, the diaphragm displacement and the diaphragm strength are systematically explored. Overall, the results reveal that in the optimized device, the target diaphragm deflection of 20 µm can be obtained using a compression force of 12 µN developed by a micro-coil input current of 0.8 A. The electromagnetic actuator proposed in this study provides an ideal solution for the pumping requirements of a variety of biomedical chips and microfluidic applications and therefore represents a valuable contribution to the ongoing development of lab-on-a-chip systems

  16. Impedance Analysis of Ovarian Cancer Cells upon Challenge with C-terminal Clostridium Perfringens Enterotoxin

    Science.gov (United States)

    Gordon, Geoffrey; Lo, Chun-Min

    2007-03-01

    Both in vitro and animal studies in breast, prostate, and ovarian cancers have shown that clostridium perfringens enterotoxin (CPE), which binds to CLDN4, may have an important therapeutic benefit, as it is rapidly cytotoxic in tissues overexpressing CLDN4. This study sought to evaluate the ability of C-terminal clostridium perfringens enterotoxin (C-CPE), a CLDN4-targetting molecule, to disrupt tight junction barrier function. Electric cell-substrate impedance sensing (ECIS) was used to measure both junctional resistance and average cell-substrate separation of ovarian cancer cell lines after exposure to C-CPE. A total of 14 ovarian cancer cell lines were used, and included cell lines derived from serous, mucinous, and clear cells. Our results showed that junctional resistance increases as CLDN4 expression increases. In addition, C-CPE is non-cytotoxic in ovarian cancer cells expressing CLDN4. However, exposure to C-CPE results in a significant (pcancer cell lines with C-CPE disrupts tight junction barrier function.

  17. Design, analysis and optimization of an electromagnetic actuator for a micro impedance pump

    Science.gov (United States)

    Chang, Hsien-Tsung; Wen, Chih-Yung; Lee, Chia-Yen

    2009-08-01

    This study designs and optimizes an electromagnetic actuator for use in a valveless micro impedance pump. The actuator is modeled to have an electroplated permanent magnet mounted on a flexible PDMS diaphragm and a planar copper micro-coil patterned on a bottom glass substrate. The constituent parts of the actuator, namely the diaphragm, the micro-coil and the magnet, are modeled, analyzed and optimized in such a way as to maximize the actuating force while simultaneously ensuring the mechanical integrity of the device. In performing the analyses, theoretical and mathematical models of the stroke volume and diaphragm deflection are developed based on thin plate theory. The design models are verified theoretically and numerically, and the relationships between the electromagnetic force, the diaphragm displacement and the diaphragm strength are systematically explored. Overall, the results reveal that in the optimized device, the target diaphragm deflection of 20 µm can be obtained using a compression force of 12 µN developed by a micro-coil input current of 0.8 A. The electromagnetic actuator proposed in this study provides an ideal solution for the pumping requirements of a variety of biomedical chips and microfluidic applications and therefore represents a valuable contribution to the ongoing development of lab-on-a-chip systems.

  18. Impedance spectroscopy analysis of human odorant binding proteins immobilized on nanopore arrays for biochemical detection.

    Science.gov (United States)

    Lu, Yanli; Zhang, Diming; Zhang, Qian; Huang, Yixuan; Luo, Senbiao; Yao, Yao; Li, Shuang; Liu, Qingjun

    2016-05-15

    Human odorant-binding proteins (hOBPs) not only can bind and transport odorants in the surrounding environment for sensing smells, but also play important roles in transmitting lots of biomolecules in different organs. Utilizing the properties of hOBPs, an electrochemical biosensor with nanopore array was developed to detect specific biomolecular ligands, such as aldehydes and fatty acids. The highly ordered nanopores of anodic aluminum oxide with diameter of 20-40 nm were fabricated with two-step oxidation. Through 2-carboxyethyl phosphonic acid, hOBPs were self-assembled on nanopores as the sensing membrane. With nanopore arrays, the impedance spectra showed quite different electron transfer processes in the frequency spectra, which could be characterized by the electron transfer resistance and electrical resistance of the porous membrane. Under stimulation of biomolecular ligands, series resistance of nanopores and hOBPs increased and showed a concentration-dependence feature, while the electron transfer resistance hardly changed. The nanopore based biosensor could sensitively detect biological ligands of benzaldehyde, docosahexaenoic acid, and lauric acid, which were closely related to or were potential biomarkers for cancers and other serious diseases. Equipped with hOBPs, the sensor exhibited promising potentials both in odorant and biomolecule detection for olfactory biosensing and in disease diagnosis and evaluation for biochemical detection. PMID:26710343

  19. Thermal Versus Impedance-Based Ablation of Renal Cell Carcinoma: A Meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Modabber, Milad, E-mail: mmodabber@gmail.com; Martin, Jason, E-mail: jason.martin@medportal.ca [McMaster University, DeGroote School of Medicine (Canada); Athreya, Sriharsha, E-mail: sathreya@stjosham.on.ca [McMaster University, Faculty of Health Sciences (Canada)

    2013-10-04

    BackgroundPercutaneous radiofrequency ablation (RFA) of renal carcinoma has become an established treatment modality. However, thermal (TB) versus impedance-based (IB)-RF generators have not been previously compared.MethodsA literature search on the application of RFA for renal masses using TB or IB-RF generators was performed. The safety, efficacy, and long-term outcomes of TB versus IB-based RFA were assessed using the outcome measures of technical success, local recurrence rate, complications, and preservation of renal function.ResultsAcross the 27 included studies, pooled results suggested comparable results for technical success (TB-RFA 98.53 % vs. IB-RFA 98.78 %, P = 0.9813). Clinical efficacy results were also similar across both generators (91.0 % TB-RFA vs. 91.5 % IB-RFA; P = 0.73). At follow-up, no differences in renal function (relative risk [RR] 0.5, 95 % confidence interval [CI] 0.45–5.48), and local recurrence (RR 0.717, 95 % CI 0.49–1.50) were observed. The pooled proportion of overall complication rates was 13.1 % for TB-RFA and 11.5 % for IB-RFA.ConclusionNo differences in the observed parameters were found either during surgery or at follow-up.

  20. Thermal Versus Impedance-Based Ablation of Renal Cell Carcinoma: A Meta-analysis

    International Nuclear Information System (INIS)

    BackgroundPercutaneous radiofrequency ablation (RFA) of renal carcinoma has become an established treatment modality. However, thermal (TB) versus impedance-based (IB)-RF generators have not been previously compared.MethodsA literature search on the application of RFA for renal masses using TB or IB-RF generators was performed. The safety, efficacy, and long-term outcomes of TB versus IB-based RFA were assessed using the outcome measures of technical success, local recurrence rate, complications, and preservation of renal function.ResultsAcross the 27 included studies, pooled results suggested comparable results for technical success (TB-RFA 98.53 % vs. IB-RFA 98.78 %, P = 0.9813). Clinical efficacy results were also similar across both generators (91.0 % TB-RFA vs. 91.5 % IB-RFA; P = 0.73). At follow-up, no differences in renal function (relative risk [RR] 0.5, 95 % confidence interval [CI] 0.45–5.48), and local recurrence (RR 0.717, 95 % CI 0.49–1.50) were observed. The pooled proportion of overall complication rates was 13.1 % for TB-RFA and 11.5 % for IB-RFA.ConclusionNo differences in the observed parameters were found either during surgery or at follow-up

  1. A Multilayer MEMS Platform for Single-Cell Electric Impedance Spectroscopy and Electrochemical Analysis

    Science.gov (United States)

    Dittami, Gregory M.; Ayliffe, H. Edward; King, Curtis S.; Rabbitt, Richard D.

    2008-01-01

    The fabrication and characterization of a microchamber electrode array for electrical and electrochemical studies of individual biological cells are presented. The geometry was tailored specifically for measurements from sensory hair cells isolated from the cochlea of the mammalian inner ear. Conventional microelectromechanical system (MEMS) fabrication techniques were combined with a heat-sealing technique and polydimethylsiloxane micromolding to achieve a multilayered microfluidic system that facilitates cell manipulation and selection. The system allowed for electrical stimulation of individual living cells and interrogation of excitable cell membrane dielectric properties as a function of space and time. A three-electrode impedimetric system was incorporated to provide the additional ability to record the time-dependent concentrations of specific biochemicals in microdomain volumes near identified regions of the cell membrane. The design and fabrication of a robust fluidic and electrical interface are also described. The interface provided the flexibility and simplicity of a “cartridge-based” approach in connecting to the MEMS devices. Cytometric measurement capabilities were characterized by using electric impedance spectroscopy (1 kHz–10 MHz) of isolated outer hair cells. Chemical sensing capability within the microchannel recording chamber was characterized by using cyclic voltammetry with varying concentrations of potassium ferricyanide (K3Fe(CN)6). Chronoamperometric recordings of electrically stimulated PC12 cells highlight the ability of the platform to resolve exocytosis events from individual cells. PMID:19756255

  2. Reliability of multifrequency segmental bioelectrical impedance analysis in measuring the character of human electricity%多频节段生物电阻抗分析法测量人体电学特征的信度研究

    Institute of Scientific and Technical Information of China (English)

    李雪迎; 于文; 王宁华

    2004-01-01

    目的:人体电阻抗特性是人体重要的物理特性之一,探讨多频节段生物电阻抗分析法测量人体节段电阻抗的可信度,对了解人体的健康状况,评价治疗效果都有重要的作用.方法:对43例受试者应用多频节段生物电阻抗分析法,在相同条件下对人体各节段电阻进行两次测量,两次测量之间间隔3 d,对测量结果进行统计分析.结果:除躯干节段对频率为5 kHz的交流电的阻抗值,其前后两次测量的相关系数偏低外,其他各项目测量所得的两次结果相关系数均>O.90.结论:应用多频节段生物电阻抗分析法测量人体成分具有较高的可重复性.

  3. 应用生物电阻抗法分析血液透析患者的人体组成%Use of Bioelectrical Impedance Analysis in Patients under Hemodialysis

    Institute of Scientific and Technical Information of China (English)

    马文君; 戚本华; 宁丽梅; 余薇

    2007-01-01

    目的 应用生物电阻抗法(BIA)检测血液透析(HD)患者身体组成的改变.方法 将122例HD稳定患者按体质指数(BMI)分为消瘦组(BMI<18.5)、正常组(BMI 18.5~23.9)和超重肥胖组(BMI≥24).采用单频体脂肪测量仪测量透析后患者的体重(WT) 、总体水(TBW)、脂肪组织(FM)和非脂肪组织(FFM),并与用Watson公式计算的TBW进行比较.同时计算尿素消除率(Kt/V).结果 (1)超重肥胖组人体组成各指标均明显高于正常组(P<0.005, P<0.001),消瘦组人体组成各指标均明显低于正常组(P均<0.001).(2)Watson公式计算的男、女TBW分别为34.4±4.2和26.9±2.7,明显低于BIA法的36.0±5.2(P<0.001)和27.7±3.8(P<0.05).(3)超重肥胖组Kt/V为1.3±0.2,明显低于正常组的1.5±0.2(P<0.001),Kt/V与BMI、TBW、FFM呈负相关(P<0.001).结论 不同BMI HD患者的人体组成变化明显,BIA对评估HD后体液平衡状态和营养状况有十分重要的意义.

  4. Research on the relationship between pregnancy and fetal birth weight by bioelectrical impedance analysis%母体生物电阻抗分析与新生儿出生体质量关系的研究

    Institute of Scientific and Technical Information of China (English)

    林锦芬; 吴元赭; 王新颖; 刘美燕

    2008-01-01

    目的:探讨孕期母体体质量增加及人体成分的改变与新生儿出生体质量间的关系.方法:选择来我院建保健卡的单胎健康孕妇70例,分别于孕中期(24~25周)和孕晚期(37~38周)测人体成分,同时监测同期胎儿生长发育状况.结果:共有63例孕妇完成所有的测量项目.孕中期和孕晚期的体质指数(BMI)、蛋白质、无机盐、肌肉量、脂肪量(FM)等与新生儿出生体质量间无相关性(P>0.05);孕中期和晚期的基础代谢率(BMR)、细胞内液(ICW),细胞外液(ECW),总体水(TBW),去脂体质(FFM),体细胞群(BCM)、上臂肌围(AMC)等与母亲体质量的增加有关,且与胎儿出生体质量呈显著相关(P<0.05).结论:孕期母体体质量的增加与母亲人体成分的组成和改变有关,并且能影响胎儿的生长发育及出生体质量,FFM是新生儿出生体质量的一个预测因素.

  5. Study on the formulas predicted for body fat of children and adolescence by using bioelectrical impedence analysis%中国7~18岁人群应用生物电阻抗法估算体脂方程

    Institute of Scientific and Technical Information of China (English)

    王京钟; 王筱桂; 胡小琪; 马冠生

    2008-01-01

    目的 建立生物电阻抗方法(BIA)测量中国儿童青少年体脂含量的应用方程.方法 按中各性别和年龄段超重的BMI参考值,将总人群分为体重正常组和超重肥胖组.以水下称重方法为标准方法,采用多元线性逐步回归方法,建立不同BMI水平7~18岁儿童青少年BIA的应用方程.结果 体重正常组方程:去脂体重(FFM,kg)=0.406weight+2.918sex+0.315H2/z+0.843;超重肥胖组方程:FFM(kg)=0.358weight+1.571sex+0.358H2/z+0.603;总人群方程:FFM(ks)=0.290weight+2222sex+0.427H2/z+1.547.三个方程的调整回归系数(r2)和标准误(SEE)分别为:0.940和2.36;0.955和2.46;0.942和2.53,方程的统计学检验均有显著性意义(ANOVA,P<0.001).结论 本研究建立的BIA应用方程与国内外同类研究相比,具有较高的可靠性.

  6. Effect of photostimulation on maize leaves’ bioelectrical response

    Directory of Open Access Journals (Sweden)

    M. P. Motsnyj

    2011-06-01

    Full Text Available Dynamics of the maize leaves’ biopotentials evoked by white, blue, green and red light stimuli with an intensity of 90 Lx illumination is analyzed. Qualitative similarity in dynamics of plant’s bioelectrical response to white and colored stimuli is determined. Hyperpolarization levels are quantitatively estimated for each experimental series. Dependence of the total hyperpolarization levels on the photostimulus wave length is detected. Mean amplitude of the hyperpolarization potentials lessens when the wave length decreases: from 57.7 mV under the red light to 27.7 mV under the blue one. Probable forms of bioelectrical response initiation in photostimulated plants are analyzed.

  7. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  8. Label-free whole blood cell differentiation based on multiple frequency AC impedance and light scattering analysis in a micro flow cytometer.

    Science.gov (United States)

    Simon, Peter; Frankowski, Marcin; Bock, Nicole; Neukammer, Jörg

    2016-06-21

    We developed a microfluidic sensor for label-free flow cytometric cell differentiation by combined multiple AC electrical impedance and light scattering analysis. The measured signals are correlated to cell volume, membrane capacity and optical properties of single cells. For an improved signal to noise ratio, the microfluidic sensor incorporates two electrode pairs for differential impedance detection. One-dimensional sheath flow focusing was implemented, which allows single particle analysis at kHz count rates. Various monodisperse particles and differentiation of leukocytes in haemolysed samples served to benchmark the microdevice applying combined AC impedance and side scatter analyses. In what follows, we demonstrate that AC impedance measurements at selected frequencies allow label-free discrimination of platelets, erythrocytes, monocytes, granulocytes and lymphocytes in whole blood samples involving dilution only. Immunofluorescence staining was applied to validate the results of the label-free cell analysis. Reliable differentiation and enumeration of cells in whole blood by AC impedance detection have the potential to support medical diagnosis for patients with haemolysis resistant erythrocytes or abnormally sensitive leucocytes, i.e. for patients suffering from anaemia or leukaemia.

  9. Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization Analysis on Anticorrosive Activity of Thiophene-2-Carbaldehyde Derivative in Acid Medium

    Directory of Open Access Journals (Sweden)

    Nimmy Kuriakose

    2014-01-01

    Full Text Available The corrosion inhibition efficiency of thiophene-2-carbaldehyde tryptophan (T2CTRY on mild steel (MS in 1 M HCl solution has been investigated and compared using weight loss measurements, electrochemical impedance spectroscopy, and potentiodynamic polarization analysis. The Schiff base exhibited very good corrosion inhibition on mild steel in HCl medium and the inhibition efficiency increased with the increase in concentration of the inhibitor. The adsorption of the inhibitor on the surface of the corroding metal obeys Freundlich isotherm. Thermodynamic parameters (Kads, ΔG ads0 were calculated using adsorption isotherm. Polarization studies revealed that T2CTRY acts as a mixed type inhibitor. A maximum of 96.2% inhibition efficiency was achieved by EIS studies at a concentration of 1 mM.

  10. Efficiency of wave impeding barrier in pipeline construction under earthquake excitation using nonlinear finite element analysis

    Indian Academy of Sciences (India)

    Fatih Goktepe; H Serdar Kuyuk; Erkan Celebi

    2014-04-01

    Earthquakes have caused colossal casualties and severe damages to engineering structures and especially leading to substantial economic loss to the underground structures and/or infrastructures. Pipelines are one of most important component of lifeline engineering. For instance, the Southern Caucasus- Eastern Turkey energy corridors are formed by several key pipelines carrying crude oil and natural gas from Azerbaijan, via Georgia, to world markets through Mediterranean Sea. Many project accomplished recently and construction of new corridors are still going on. They should be protected from earthquake disaster especially when they pass through high seismicity zones. The installation of wave impeding barriers (WIB) below the vulnerable infrastructures as pipelines established in soft soil can be used to reduce the effect of the earthquake induced ground borne vibrations. In this paper, a WIB as artificial bedrock based on the cut-off frequency of a soil layer over bedrock is proposed as isolation measurement in order to mitigate the dynamic response of the buried pipelines under earthquake strong ground motion. The computational simulation of the wave propagation problem is directly achieved by employing nonlinear 2D finite element modelling for prediction of screening performance of WIB on the dynamic response of vibrating coupled soil-pipeline system. Energy absorbing boundaries along the truncated interfaces of the unbounded nature of the underlying soil media are implemented in the time domain along with Newmark’s integration. An extensive parametric investigation and systematic computations are performed with different controlling parameters. The obtained numerical results point out that WIB can be very promising as an isolator to protect pipelines when they establish for a certain depth.

  11. Alternating current impedance spectroscopic analysis of biofunctionalized vertically-aligned silica nanospring surface for biosensor applications

    Science.gov (United States)

    Timalsina, Yukta P.

    In this dissertation, a process of vertically-aligned (silica) nanosprings (VANS) based biosensor development is presented. Alternating current (AC) impedance spectroscopy has been used to analyze sensor response as a function of saline phosphate (SP) buffer and biological solutions. The sensor is a parallel plate capacitor consisting of two glass substrates coated with indium tin oxide (ITO), where the VANS [or randomly-aligned nanosprings (RANS)] grown on one substrate serve as the dielectric spacer layer. The response of a VANS device as a function of ionic concentration in SP buffer was examined and an equivalent circuit model was developed. The results demonstrated that VANS sensors exhibited greater sensitivity to the changes in SP concentration relative to the ITO sensors, which serve as controls. The biofunctionalized VANS surface via physisorption and the cross-linker method demonstrates the repeatability, specificity, and selectivity of the binding. The physisorption of biotinylated immunoglobulin G (B-IgG) onto the VANS surface simplifies the whole sensing procedure for the detection of glucose oxidase, since the avidin-conjugated glucose oxidase (Av-GOx) can directly be immobilized on the B-IgG. The cross linker method involves the covalent attachment of antibodies onto the functionalized VANS surface via imine bond. The experiments revealed that the VANS sensor response is solely the result of the interaction of target molecule i.e. mouse IgG with the probe layer, i.e. goat antimouse IgG (GalphaM IgG). It was determined that VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls above 100 Hz, which indicates that the addition of biomolecules inhibits the diffusion of ions and changes the effective dielectric response of the VANS via biomolecular polarization. The study of ionic transport in nanosprings suggested that conductance follows a scaling law. It was demonstrated that a VANS-based device

  12. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    Science.gov (United States)

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation.

  13. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    Science.gov (United States)

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation. PMID:27162144

  14. Bioelectric Control of a 757 Class High Fidelity Aircraft Simulation

    Science.gov (United States)

    Jorgensen, Charles; Wheeler, Kevin; Stepniewski, Slawomir; Norvig, Peter (Technical Monitor)

    2000-01-01

    This paper presents results of a recent experiment in fine grain Electromyographic (EMG) signal recognition, We demonstrate bioelectric flight control of 757 class simulation aircraft landing at San Francisco International Airport. The physical instrumentality of a pilot control stick is not used. A pilot closes a fist in empty air and performs control movements which are captured by a dry electrode array on the arm, analyzed and routed through a flight director permitting full pilot outer loop control of the simulation. A Vision Dome immersive display is used to create a VR world for the aircraft body mechanics and flight changes to pilot movements. Inner loop surfaces and differential aircraft thrust is controlled using a hybrid neural network architecture that combines a damage adaptive controller (Jorgensen 1998, Totah 1998) with a propulsion only based control system (Bull & Kaneshige 1997). Thus the 757 aircraft is not only being flown bioelectrically at the pilot level but also demonstrates damage adaptive neural network control permitting adaptation to severe changes in the physical flight characteristics of the aircraft at the inner loop level. To compensate for accident scenarios, the aircraft uses remaining control surface authority and differential thrust from the engines. To the best of our knowledge this is the first time real time bioelectric fine-grained control, differential thrust based control, and neural network damage adaptive control have been integrated into a single flight demonstration. The paper describes the EMG pattern recognition system and the bioelectric pattern recognition methodology.

  15. Electrochemical impedance spectroscopy analysis with a symmetric cell for LiCoO2 cathode degradation correlated with Co dissolution

    Directory of Open Access Journals (Sweden)

    Hiroki Nara

    2016-04-01

    Full Text Available Static degradation of LiCoO2 cathodes is a problem that hinders accurate analysis using our developed separable symmetric cell. Therefore, in this study we investigate the static degradation of LiCoO2 cathodes in separable symmetric cells by electrochemical impedance spectroscopy (EIS and inductively coupled plasma analyses. EIS measurements of LiCoO2 cathodes are conducted in various electrolytes, with different anions and with or without HF and/or H2O. This allows us to determine the static degradation of LiCoO2 cathodes relative to their increase of charge transfer resistance. The increase of the charge transfer resistance of the LiCoO2 cathodes is attributed to cobalt dissolution from the active material of LiCoO2. Cobalt dissolution from LiCoO2 is revealed to occur even at low potential in the presence of HF, which is generated from LiPF6 and H2O. The results indicate that avoidance of HF generation is important for the analysis of lithium-ion battery electrodes by using the separable cell. These findings reveal the condition to achieve accurate analysis by EIS using the separable cell.

  16. Electromagnetic Scattering Analysis of Coated Conductors With Edges Using the Method of Auxiliary Sources (MAS) in Conjunction With the Standard Impedance Boundary Condition (SIBC)

    DEFF Research Database (Denmark)

    Anastassiu, H.T.; D.I.Kaklamani, H.T.; Economou, D.P.;

    2002-01-01

    A novel combination of the method of auxiliary sources (MAS) and the standard impedance boundary condition (SIBC) is employed in the analysis of transverse magnetic (TM) plane wave scattering from infinite, coated, perfectly conducting cylinders with square cross sections. The scatterer...

  17. Exploring characteristics of bioelectricity generation and dye decolorization of mixed and pure bacterial cultures from wine-bearing wastewater treatment.

    Science.gov (United States)

    Han, Jing-Long; Liu, Ying; Chang, Chang-Tang; Chen, Bor-Yann; Chen, Wen-Ming; Xu, Hui-Zhong

    2011-04-01

    This study uncovered microbial characteristics of bioelectricity generation and dye decolorization in single-chamber microbial fuel cells (MFCs) using activated sludge for wine-containing wastewater treatment. Phylogenetic tree analysis on 16S rRNA gene fragments indicated that the predominant strains on anodic biofilm in acclimatized MFCs were Gamma-Proteobacteria Aeromonas punctata NIU-P9, Pseudomonas plecoglossicida NIU-Y3, Pseudomonas koreensis NIU-X8, Acinetobacter junii NIU-Y8, Stenotrophomonas maltophila NIU-X2. Our findings showed that the current production capabilities of these pure strains were only ca. 10% of those of their mother activated sludge, indicating that synergistic interactions among microbes might be the most influential factor to maximize power generation in MFCs. Plus, these electrochemically active strains also performed reductive decolorization of C.I. reactive blue 160, suggesting that bioelectricity generation might be directly associated to azo dye decolorization to deal with electron transfer on anodic biofilm in MFCs.

  18. Electrical impedance spectroscopy (EIS)-based evaluation of biological tissue phantoms to study multifrequency electrical impedance tomography (Mf-EIT) systems

    KAUST Repository

    Bera, Tushar Kanti

    2016-03-18

    Abstract: Electrical impedance tomography (EIT) phantoms are essential for the calibration, comparison and evaluation of the EIT systems. In EIT, the practical phantoms are typically developed based on inhomogeneities surrounded by a homogeneous background to simulate a suitable conductivity contrast. In multifrequency EIT (Mf-EIT) evaluation, the phantoms must be developed with the materials which have recognizable or distinguishable impedance variations over a wide range of frequencies. In this direction the impedance responses of the saline solution (background) and a number vegetable and fruit tissues (inhomogeneities) are studied with electrical impedance spectroscopy (EIS) and the frequency responses of bioelectrical impedance and conductivity are analyzed. A number of practical phantoms with different tissue inhomogeneities and different inhomogeneity configurations are developed and the multifrequency impedance imaging is studied with the Mf-EIT system to evaluate the phantoms. The conductivity of the vegetable inhomogeneities reconstructed from the EIT imaging is compared with the conductivity values obtained from the EIS studies. Experimental results obtained from multifrequency EIT reconstruction demonstrate that the electrical impedance of all the biological tissues inhomogenity decreases with frequency. The potato tissue phantom produces better impedance image in high frequency ranges compared to the cucumber phantom, because the cucumber impedance at high frequency becomes lesser than that of the potato at the same frequency range. Graphical Abstract: [Figure not available: see fulltext.] © 2016 The Visualization Society of Japan

  19. Analysis of low-dimensional radio-frequency impedance-based cardio-synchronous waveforms for biometric authentication.

    Science.gov (United States)

    Venugopalan, Shreyas; Savvides, Marios; Griofa, Marc O; Cohen, Ken

    2014-08-01

    Over the past two decades, there have been a lot of advances in the field of pattern analyses for biomedical signals, which have helped in both medical diagnoses and in furthering our understanding of the human body. A relatively recent area of interest is the utility of biomedical signals in the field of biometrics, i.e., for user identification. Seminal work in this domain has already been done using electrocardiograph (ECG) signals. In this paper, we discuss our ongoing work in using a relatively recent modality of biomedical signals-a cardio-synchronous waveform measured using a Radio-Frequency Impedance-Interrogation (RFII) device for the purpose of user identification. Compared to an ECG setup, this device is noninvasive and measurements can be obtained easily and quickly. Here, we discuss the feasibility of reducing the dimensions of these signals by projecting onto various subspaces while still preserving interuser discriminating information. We compare the classification performance using classical dimensionality reduction methods such as principal component analysis (PCA), independent component analysis (ICA), random projections, with more recent techniques such as K-SVD-based dictionary learning. We also report the reconstruction accuracies in these subspaces. Our results show that the dimensionality of the measured signals can be reduced by 60 fold while maintaining high user identification rates. PMID:23846435

  20. Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators%Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators

    Institute of Scientific and Technical Information of China (English)

    呼义翔; 雷天时; 孙风举; 黄涛; 邱爱慈; 丛培天; 王亮平; 曾江涛; 李岩; 张信军

    2011-01-01

    Based on the transmission line code TLCODE, a 1D circuit model for a transmission- line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy- transport and power-transport for a transmission-line impedance transformer as functions of ψ (the ratio of the output impedance to the input impedance of the transformer) and Г (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in Г, from 0 to ∞, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%.

  1. FEM Analysis of Beam-coupling Impedance and RF Contacts Criticality on the LHC UA9 Piezo Goniometer

    CERN Document Server

    Danisi, A; Passarelli, A; Masi, A; Losito, R; Salvant, B

    2014-01-01

    The UA9 piezo-goniometer has been designed to guarantee micro-radians-accuracy angular positioning of a silicon crystal for a crystal collimation experiment in the LHC, and to minimize the impact on the LHC beam coupling impedance. This paper presents a Finite Element Method (FEM) study of the device, in both parking and operational positions, to evaluate its impact on the LHC impedance budget. In addition, the shielding contribution of the RF gaskets has been carefully evaluated, with the objective to assess the consequences for operation in case of their failure. A final word is drawn on the overall device impedance criticality.

  2. EFFECTS OF FOOD AND DRINK INGESTION ON BODY COMPOSITION VARIABLES OF ABDOMINAL BIOELECTRICAL IMPEDANCE.

    Science.gov (United States)

    Fernández Vázquez, Rosalía; Martínez Blanco, Javier; García Vega, María del Mar; Barbancho, Miguel Ángel; Alvero-Cruz, José Ramón

    2015-11-01

    Objetivo: conocer los cambios en la grasa del tronco y el nivel de grasa visceral determinado por BIA abdominal, así como otras medidas antropométricas relacionadas con la grasa abdominal o central después de la ingestión de una comida. Métodos: se realizó un protocolo experimental para evaluar un estudio descriptivo de intervención longitudinal. Los participantes fueron 21 sujetos (10 hombres y 11 mujeres), voluntarios que tuvieron acceso a una evaluación médica, con una edad de 74 años ± 13,43. Las mediciones antropométricas fueron: circunferencia de la cintura máxima en posición de pie, circunferencia de la cintura a nivel del ombligo en posición de decúbito supino y diámetro sagital abdominal (SAD). Además se obtuvo la grasa del tronco y el nivel de grasa visceral, por análisis de impedancia bioeléctrica abdominal, con un dispositivo Tanita AB-140 (ViScan), todo ello antes y después de una ración de comida. Resultados: las medidas antropométricas, como la circunferencia de la cintura en posición supina y SAD, no mostraron diferencias significativas (P > 0,05), después de la ingestión de alimentos, a excepción de un aumento significativo de la circunferencia de la cintura máxima en posición de pie (P 0,05). Los cambios porcentuales de las medidas fueron menores del 2% para la circunferencia de la cintura en posición de pie, para la circunferencia de cintura por Viscan, para el diámetro sagital abdominal y la grasa del tronco, y un 5,9% para el nivel de grasa visceral. Conclusiones: los efectos de una comida y bebida sobre la grasa del tronco y el nivel de grasa visceral, medidas por impedancia bioeléctrica abdominal, son mínimas, aunque siempre es recomendable hacerlo en condiciones de ayuno.

  3. Pengembangan Bioelectrical Impedance Sebagai Control Commands Pengaturan Kecepatan Gerak Kursi Roda Dengan Metoda PID Controller

    OpenAIRE

    Juli Sardi; Ali Basrah Pulungan

    2014-01-01

    In the present study, bioimpedance signals of human body was utilized to control speed of a wheelchair movement. A bioimpedance is electrically passive part contained the body tissues. The research is one of alternative solutions for patients with paralysis of the upper and lower limb. Firstly, design of system of the research consisted of bioimpedance measuring instruments and a mechanical design of the wheelchair. Bioimpedance measurement was performed by injecting a sinusoidal current sour...

  4. Pengembangan Bioelectrical Impedance Sebagai Control Commands Pengaturan Kecepatan Gerak Kursi Roda Dengan Metoda PID Controller

    Directory of Open Access Journals (Sweden)

    Juli Sardi

    2014-09-01

    Full Text Available In the present study, bioimpedance signals of human body was utilized to control speed of a wheelchair movement. A bioimpedance is electrically passive part contained the body tissues. The research is one of alternative solutions for patients with paralysis of the upper and lower limb. Firstly, design of system of the research consisted of bioimpedance measuring instruments and a mechanical design of the wheelchair. Bioimpedance measurement was performed by injecting a sinusoidal current source of 0.5 mArms with a frequency of 50 kHz to muscle tissue (shoulder to obtain the output voltage in the range of 0-5 Vdc. With impulse and manual thresholding methods, the voltage signal was classified into several controls command to adjust the speed and direction of the wheelchair control based on PID Controller. The experimental result of the research was realization of bioimpedance signal that used as a reference to control the direction and speed of the wheelchair with a success rate of 86.7 %. A wheelchair velocity was classified into three types of motion, namely slow, medium and fast. Slow speed has a rated speed of 30 Cm/s, medium speed value speed of 40 Cm/s and fast speed value of 50 Cm/s. The wheelchair can also turn to the left and the right in accordance with the wishes of wheelchair user beside to moving forward.

  5. Body Composition of Bangladeshi Children: Comparison and Development of Leg-to-Leg Bioelectrical Impedance Equation

    OpenAIRE

    Khan, I. (Imran); Hawkesworth, Ashraful; Hawlader, Sophie Mohammad Delwer Hossain; Arifeen, Shams El; Moore, Sophie; Hills, Andrew P; Wells, Jonathan C.; Persson, Lars-Åke; Kabir, Iqbal

    2012-01-01

    The aim of this study was to investigate the validity of the Tanita TBF 300A leg-to-leg bioimpedance analyzer for estimating fat-free mass (FFM) in Bangladeshi children aged 4-10 years and to develop novel prediction equations for use in this population, using deuterium dilution as the reference method. Two hundred Bangladeshi children were enrolled. The isotope dilution technique with deuterium oxide was used for estimation of total body water (TBW). FFM estimated by Tanita was compared with...

  6. Bioelectrical impedance spectroscopy to estimate fluid balance in critically ill patients.

    Science.gov (United States)

    Dewitte, Antoine; Carles, Pauline; Joannès-Boyau, Olivier; Fleureau, Catherine; Roze, Hadrien; Combe, Christian; Ouattara, Alexandre

    2016-04-01

    Fluid management is a crucial issue in intensive-care medicine. This study evaluated the feasibility and reproducibility of bioimpedance spectroscopy to measure body-water composition in critically ill patients, and compared fluid balance and daily changes in total body water (TBW) measured by bioimpedance. This observational study included 25 patients under mechanical ventilation. Fluid balance and bioimpedance measurements were recorded on 3 consecutive days. Whole-body bioimpedance spectroscopy was performed with exact or ideal body weights entered into the device, and with or without ICU monitoring. Reproducibility of bioimpedance spectroscopy was very good in all conditions despite ICU monitoring and mechanical ventilation. Bioimpedance measurements using an ideal body weight varied significantly, making the weighing procedure necessary. Comparison of fluid balance and daily changes in body weight provided the best correlation (ρ = 0.74; P 10 (ρ = 0.36; P = 0.05) and with extracorporeal circulation (ρ = 0.50; P = 0.005). Regardless of the technique used to estimate volume status, important limits of agreement were observed. Non-invasive determination of body-water composition using bioimpedance spectroscopy is feasible in critically ill patients but requires knowledge of the patient's weight. The best method to assess volume status after fluid resuscitation and the value gained from information about body composition provided by bioimpedance techniques needs further evaluation. PMID:26018457

  7. Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi;

    2016-01-01

    adequate power flow studies. In this paper, power flow analyses for both AC and DC microgrids are formulated and implemented. The mathematical models for both types of microgrids considering the concept of virtual impedance are used to be in conformity with the practical control of the distributed......In the Low-Voltage (LV) AC microgrids (MGs), with a relatively high R/X ratio, virtual impedance is usually adopted to improve the performance of droop control applied to Distributed Generators (DGs). At the same time, LV DC microgrid using virtual impedance as droop control is emerging without...... generators. As a result, calculation accuracy is improved for both AC and DC microgrid power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation...

  8. AN IMPEDANCE ANALYSIS FOR CRACK DETECTION IN THE TIMOSHENKO BEAM BASED ON THE ANTI-RESONANCE TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An alternative technique for crack detection in a Timoshenko beam based on the first anti-resonant frequency is presented in this paper. Unlike the natural frequency, the anti-resonant frequency is a local parameter rather than a global parameter of structures, thus the proposed technique can be used to locate the structural defects. An impedance analysis of a cracked beam stimulated by a harmonic force based on the Timoshenko beam formulation is investigated. In order to characterize the local discontinuity due to cracks, a rotational spring model based on fracture mechanics is proposed to model the crack. Subsequently, the proposed method is verified by a numerical example of a simply-supported beam with a crack. The effect of the crack size on the anti-resonant frequency is investigated. The position of the crack of the simply-supported beam is also determined by the anti-resonance technique. The proposed technique is further applied to the "contaminated" anti-resonant frequency to detect crack damage, which is obtained by adding 1-3% noise to the calculated data. It is found that the proposed technique is effective and free from the environment noise. Finally, an experimental study is performed, which further verifies the validity of the proposed crack identification technique.

  9. Cold vacuum chamber for diagnostics: Analysis of the measurements at the Diamond Light Source and impedance bench measurements

    Science.gov (United States)

    Voutta, R.; Gerstl, S.; Casalbuoni, S.; Grau, A. W.; Holubek, T.; Saez de Jauregui, D.; Bartolini, R.; Cox, M. P.; Longhi, E. C.; Rehm, G.; Schouten, J. C.; Walker, R. P.; Migliorati, M.; Spataro, B.

    2016-05-01

    The beam heat load is an important input parameter needed for the cryogenic design of superconducting insertion devices. Theoretical models taking into account the different heating mechanisms of an electron beam to a cold bore predict smaller values than the ones measured with several superconducting insertion devices installed in different electron storage rings. In order to measure and possibly understand the beam heat load to a cold bore, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. COLDDIAG is equipped with temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers which allow to measure the beam heat load, total pressure, and gas content as well as the flux of particles hitting the chamber walls. COLDDIAG was installed in a straight section of the Diamond Light Source (DLS). In a previous paper the experimental equipment as well as the installation of COLDDIAG in the DLS are described [S. Gerstl et al., Phys. Rev. ST Accel. Beams 17, 103201 (2014)]. In this paper we present an overview of all the measurements performed with COLDDIAG at the DLS and their detailed analysis, as well as impedance bench measurements of the cold beam vacuum chamber performed at the Karlsruhe Institute of Technology after removal from the DLS. Relevant conclusions for the cryogenic design of superconducting insertion devices are drawn from the obtained results.

  10. Oxygen diffusion in niobia-doped zirconia as surrogate for oxide film on Zr–Nb alloy: AC impedance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yamana, Teppei; Arima, Tatsumi, E-mail: arima@nucl.kyushu-u.ac.jp; Yoshihara, Takatoshi; Inagaki, Yaohiro; Idemitsu, Kazuya

    2013-11-15

    The oxygen conductivities and crystallographic properties of niobia-doped yttria-stabilized tetragonal zirconia with 0.0–2.6 wt% Nb{sub 2}O{sub 5} were evaluated by the AC impedance analysis and the X-ray diffraction measurement, respectively. The tetragonality of zirconia increased with niobia content and approached ∼1.017 while the tetragonal-to-monoclinic phase transition occurred above ca. 1 wt% Nb{sub 2}O{sub 5}. On the other hand, oxygen conductivities of bulk and grain-boundary (GB) decreased with increasing niobia content. The bulk conductivity controlled the total ionic conductivity at high temperatures, and its activation energy had smaller dependence on temperature than that of GB. In addition to the effect of [V{sub O}{sup ··}] depletion by niobia addition, the behaviors of bulk and GB conductivities might be explained by the decrease of mobility of oxygen ion due to Coulomb repulsion between Nb{sup 5+} and V{sub O}{sup ··} and by no segregation of Nb ions in the space-charge layers, respectively.

  11. NOVEL DESIGN OF A BIOELECTRIC AMPLIFIER WITH MINIMIZED MAGNITUDE AND PHASE ERRORS

    Institute of Scientific and Technical Information of China (English)

    Mashhour Bani Amer; Assistant Professor

    2001-01-01

    A new design of a bioelectric amplifier that has better parameters than conventional designs is presented. The design allows the construction of bioelectric amplifier with improved parameters in terms of common-mode rejection ratio and phase and magnitude errors. The voltage gain is easily adapted to a wide range of biomedical applications. The experimental and simulation results of the designed bioelectric amplifier are also included.

  12. Heterogeneous silicon mesostructures for lipid-supported bioelectric interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yuanwen; Carvalho-de-Souza, João L.; Wong, Raymond C. S.; Luo, Zhiqiang; Isheim, Dieter; Zuo, Xiaobing; Nicholls, Alan W.; Jung, Il Woong; Yue, Jiping; Liu, Di-Jia; Wang, Yucai; De Andrade, Vincent; Xiao, Xianghui; Navrazhnykh, Luizetta; Weiss, Dara E.; Wu, Xiaoyang; Seidman, David N.; Bezanilla, Francisco; Tian, Bozhi

    2016-06-27

    Silicon-based materials have widespread application as biophysical tools and biomedical devices. Here we introduce a biocompatible and degradable mesostructured form of silicon with multi-scale structural and chemical heterogeneities. The material was synthesized using mesoporous silica as a template through a chemical vapour deposition process. It has an amorphous atomic structure, an ordered nanowire-based framework and random submicrometre voids, and shows an average Young’s modulus that is 2–3 orders of magnitude smaller than that of single-crystalline silicon. In addition, we used the heterogeneous silicon mesostructures to design a lipid-bilayer-supported bioelectric interface that is remotely controlled and temporally transient, and that permits non-genetic and subcellular optical modulation of the electrophysiology dynamics in single dorsal root ganglia neurons. Our findings suggest that the biomimetic expansion of silicon into heterogeneous and deformable forms can open up opportunities in extracellular biomaterial or bioelectric systems.

  13. Heterogeneous silicon mesostructures for lipid-supported bioelectric interfaces

    Science.gov (United States)

    Jiang, Yuanwen; Carvalho-de-Souza, João L.; Wong, Raymond C. S.; Luo, Zhiqiang; Isheim, Dieter; Zuo, Xiaobing; Nicholls, Alan W.; Jung, Il Woong; Yue, Jiping; Liu, Di-Jia; Wang, Yucai; de Andrade, Vincent; Xiao, Xianghui; Navrazhnykh, Luizetta; Weiss, Dara E.; Wu, Xiaoyang; Seidman, David N.; Bezanilla, Francisco; Tian, Bozhi

    2016-09-01

    Silicon-based materials have widespread application as biophysical tools and biomedical devices. Here we introduce a biocompatible and degradable mesostructured form of silicon with multi-scale structural and chemical heterogeneities. The material was synthesized using mesoporous silica as a template through a chemical vapour deposition process. It has an amorphous atomic structure, an ordered nanowire-based framework and random submicrometre voids, and shows an average Young's modulus that is 2-3 orders of magnitude smaller than that of single-crystalline silicon. In addition, we used the heterogeneous silicon mesostructures to design a lipid-bilayer-supported bioelectric interface that is remotely controlled and temporally transient, and that permits non-genetic and subcellular optical modulation of the electrophysiology dynamics in single dorsal root ganglia neurons. Our findings suggest that the biomimetic expansion of silicon into heterogeneous and deformable forms can open up opportunities in extracellular biomaterial or bioelectric systems.

  14. Bioelectrical Signals as Emerging Biometrics: Issues and Challenges

    OpenAIRE

    Yogendra Narain Singh; Sanjay Kumar Singh; Amit Kumar Ray

    2012-01-01

    This paper presents the effectiveness of bioelectrical signals such as the electrocardiogram (ECG) and the electroencephalogram (EEG) for biometric applications. Studies show that the impulses of cardiac rhythm and electrical activity of the brain recorded in ECG and EEG, respectively; have unique features among individuals, therefore they can be suggested to be used as biometrics for identity verification. The favourable characteristics to use the ECG or EEG signals as biometric include univ...

  15. [Endocrine obesity: bioelectric profiles (biotypes) detected in the body composition].

    Science.gov (United States)

    Miggiano, G A D; Petitti, T

    2004-09-01

    136 patients were selected (16 men and 120 women with non-specific menstrual disturbances) with a BMI (Body Mass Index) between 25 and 45 kg/m2, which were diagnosed with "disendocrinia" (GH deficit, hyperadrenocorticism, hypothyroidsm, hyperandrogenism, menstrual cycle disorders). The proposed approach, based on the visualization of the value distribution of the electric measures in different graphics, is able to immediately explain the bioelectric state of the individual's lean-mass. Subjects with hypothyroidism present, along with their overweight, less bio-conducting mass, with an altered fluid intra/extra-cellular distribution. Patients with hyperadrenocorticism show instead an hyperhydratation of the body mass, especially in the extracellular level. Patients with menstrual disorders (amenorrea, polycystic ovary syndrome, anovulatory cycle etc...) present a lean mass reduction (elevated Rs) and an increase of the intra-cellular compartment (elevated-Xc). Patients with hyper-androgenism (and hirsutism) show a characteristic bioelectric "pattern", with low Rs levels and high Xc levels. Subjects with GH deficit (men and women), has a trend of documenting bioelectric measures with lower lean mass and higher fat-mass. Different electric biotypes seem to characterize the body composition in the several endocrine disorders. PMID:15700636

  16. A Bioassay System Using Bioelectric Signals from Small Fish

    Science.gov (United States)

    Terawaki, Mitsuru; Soh, Zu; Hirano, Akira; Tsuji, Toshio

    Although the quality of tap water is generally examined using chemical assay, this method cannot be used for examination in real time. Against such a background, the technique of fish bioassay has attracted attention as an approach that enables constant monitoring of aquatic contamination. The respiratory rhythms of fish are considered an efficient indicator for the ongoing assessment of water quality, since they are sensitive to chemicals and can be indirectly measured from bioelectric signals generated by breathing. In order to judge aquatic contamination accurately, it is necessary to measure bioelectric signals from fish swimming freely as well as to stably discriminate measured signals, which vary between individuals. However, no bioassay system meeting the above requirements has yet been established. This paper proposes a bioassay system using bioelectric signals generated from small fish in free-swimming conditions. The system records signals using multiple electrodes to cover the extensive measurement range required in a free-swimming environment, and automatically discriminates changes in water quality from signal frequency components. This discrimination is achieved through an ensemble classification method using probability neural networks to solve the problem of differences between individual fish. The paper also reports on the results of related validation experiments, which showed that the proposed system was able to stably discriminate between water conditions before and after bleach exposure.

  17. [Highly Efficient Bilayer-Structure Yellow-Green OLED with MADN Hole-Transport Layer and the Impedance Spectroscopy Analysis].

    Science.gov (United States)

    Zhang, Xiao-wen; Mo, Bing-jie; Liu, Li-ming; Wang, Hong-hang; Chen, Er-wei; Xu, Ji-wen; Wang, Hua

    2015-12-01

    Abstract Highly efficient bilayer-structure yellow-green organic light-emitting device (OLED) has been demonstrated based on MADN as hole-transport layer (HTL) and host-guest coped system of [Alq₃: 0.7 Wt% rubrene] as emitting and electron-trans- port layer. The device gives yellow-green emission through incomplete energy transfer from the host of Alq₃ to the guest of ru- brene. An electroluminescent peak of 560 nm, 1931 CIE color coordinates of (0.46, 0.52) and a maximum current efficiency of 7.63 cd · A⁻¹ (which has been enhanced by 30% in comparison with the counterpart having conventional NPB HTL) are ob- served. The hole-transporting characteristics of MADN and NPB have been systematically investigated by constructing hole-only devices and employing impedance spectroscopy analysis. Our results indicate that MADN can be served as an effective hole-trans- port material and its hole-transporting ability is slightly inferior to NPB. This overcomes the shortcoming of hole transporting more quickly than electron in OLED and improves carrier balance in the emitting layer. Consequently, the device current efficien- cy is promoted. In addition, the current efficiency of bilayer-structure OLED with MADN as HTL is comparable to that of conv- entinol trilayer-structure device with MADN as HTL and Alq₃ as electron-transport layer. This indicates that the simplified bi- layer-structure device can be achieved without sacrificing current efficiency. The emitting layer of [Alq: 0.7 Wt% rubrene possesses superior elecron-transporting ability. PMID:26964197

  18. Dielectric properties, impedance analysis and modulus behavior of CaTiO3 ceramic prepared by solid state reaction

    International Nuclear Information System (INIS)

    Highlights: •A single phase orthorhombic CaTiO3 structure with sub-micron grains is produced. •The frequency exponent ‘s’ is temperature dependent and explained by CBH model. •The dielectric constant and loss tangent are frequency and temperature dependent. •The modulus plot reveals the presence of thermally activated dielectric relaxation. •Cole-cole plot reveals two primary relaxation processes exist in the sample. -- Abstract: Calcium titanate (CaTiO3) with the general formula for perovskites, ABO3, is of technological importance, particularly with regard to dielectric properties. In this work, CaTiO3 ceramic material was prepared by the conventional solid state reaction method. The dielectric properties, impedance characteristics and modulus behavior of the CaTiO3 ceramic material sintered at 1240 °C were investigated in the frequency range of 10−2–106 Hz and temperature range of 100–250 °C. The XRD analysis of the sintered CaTiO3 shows that it is an orthorhombic structure with lattice parameters a = 5.4398 Å, b = 7.6417 Å, and c = 5.3830 Å. The FESEM micrograph shows a significant difference in grain size distribution ranging from 0.26 to 2.32 μm. The AC conductivity, σAC, is found to increase with increasing temperature within the frequency range of 10−2–106 Hz confirming the hopping of electrons to be the conduction mechanism. Due to the decreasing values of the frequency exponent s with increasing temperature, the results of the σAC are discussed using the correlated barrier height (CBH) model. For dielectric studies, the dielectric constant, ε′ is found to decrease with increasing frequency. In the whole temperature range of 100–250 °C, high and low frequency plateau are observed. Each converges at high frequency (>105 Hz) for all the temperatures. The frequency dependence of loss tangent, tan δ, decreases with rise in temperature, with the loss tangent peak shifting to higher frequency. Due to its dielectric

  19. Dielectric properties, impedance analysis and modulus behavior of CaTiO{sub 3} ceramic prepared by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Y.J., E-mail: yjeng_86@hotmail.com [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hassan, J., E-mail: jumiah@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, M., E-mail: mansor@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2013-09-15

    Highlights: •A single phase orthorhombic CaTiO{sub 3} structure with sub-micron grains is produced. •The frequency exponent ‘s’ is temperature dependent and explained by CBH model. •The dielectric constant and loss tangent are frequency and temperature dependent. •The modulus plot reveals the presence of thermally activated dielectric relaxation. •Cole-cole plot reveals two primary relaxation processes exist in the sample. -- Abstract: Calcium titanate (CaTiO{sub 3}) with the general formula for perovskites, ABO{sub 3}, is of technological importance, particularly with regard to dielectric properties. In this work, CaTiO{sub 3} ceramic material was prepared by the conventional solid state reaction method. The dielectric properties, impedance characteristics and modulus behavior of the CaTiO{sub 3} ceramic material sintered at 1240 °C were investigated in the frequency range of 10{sup −2}–10{sup 6} Hz and temperature range of 100–250 °C. The XRD analysis of the sintered CaTiO{sub 3} shows that it is an orthorhombic structure with lattice parameters a = 5.4398 Å, b = 7.6417 Å, and c = 5.3830 Å. The FESEM micrograph shows a significant difference in grain size distribution ranging from 0.26 to 2.32 μm. The AC conductivity, σ{sub AC}, is found to increase with increasing temperature within the frequency range of 10{sup −2}–10{sup 6} Hz confirming the hopping of electrons to be the conduction mechanism. Due to the decreasing values of the frequency exponent s with increasing temperature, the results of the σ{sub AC} are discussed using the correlated barrier height (CBH) model. For dielectric studies, the dielectric constant, ε′ is found to decrease with increasing frequency. In the whole temperature range of 100–250 °C, high and low frequency plateau are observed. Each converges at high frequency (>10{sup 5} Hz) for all the temperatures. The frequency dependence of loss tangent, tan δ, decreases with rise in temperature, with the

  20. CFD analysis of the human airways under impedance-based boundary conditions: application to healthy, diseased and stented trachea.

    Science.gov (United States)

    Malvè, M; Chandra, S; López-Villalobos, J L; Finol, E A; Ginel, A; Doblaré, M

    2013-01-01

    A computational fluid dynamics model of a healthy, a stenotic and a post-operatory stented human trachea was developed to study the respiration under physiological boundary conditions. For this, outflow pressure waveforms were computed from patient-specific spirometries by means of a method that allows to compute the peripheral impedance of the truncated bronchial generation, modelling the lungs as fractal networks. Intratracheal flow pattern was analysed under different scenarios. First, results obtained using different outflow conditions were compared for the healthy trachea in order to assess the importance of using impedance-based conditions. The resulted intratracheal pressures were affected by the different boundary conditions, while the resulted velocity field was unaffected. Impedance conditions were finally applied to the diseased and the stented trachea. The proposed impedance method represents an attractive tool to compute physiological pressure conditions that are not possible to extract in vivo. This method can be applied to healthy, pre- and post-operatory tracheas showing the possibility of predicting, through numerical simulation, the flow and the pressure field before and after surgery.

  1. Application of the Method of Auxiliary Sources for the Analysis of Plane-Wave Scattering by Impedance Spheres

    DEFF Research Database (Denmark)

    Karamehmedovic, Mirza; Breinbjerg, Olav

    2002-01-01

    The Method of Auxiliary Sources (MAS) is applied to 3D scattering problems involving spherical impedance scatterers. The MAS results are compared with the reference spherical wave expansion (SWE) solution. It is demonstrated that good agreement is achieved between the MAS and SWE results....

  2. Topological change and impedance spectrum of rat olfactory receptor I7: A comparative analysis with bovine rhodopsin and bacteriorhodopsin

    Science.gov (United States)

    Alfinito, Eleonora; Pennetta, Cecilia; Reggiani, Lino

    2009-04-01

    We present a theoretical investigation on possible selection of olfactory receptors (ORs) as sensing components of nanobiosensors. Accordingly, we generate the impedance spectra of the rat OR I7 in the native and activated states and analyze their differences. In this way, we connect the protein morphological transformation, caused by the sensing action, with its change in electrical impedance. The results are compared with those obtained by studying the best known protein of the G protein coupled receptor (GPCR) family: bovine rhodopsin. Our investigations indicate that a change in morphology goes with a change in impedance spectrum mostly associated with a decrease in the static impedance up to about 60% of the initial value, in qualitative agreement with existing experiments on rat OR I7. The predictiveness of the model is tested successfully for the case of recent experiments on bacteriorhodopsin. The present results point to a promising development of a new class of nanobiosensors based on the electrical properties of GPCR and other sensing proteins.

  3. Impedance analysis of Bi3.25La0.75Ti3O12 ferroelectric ceramic

    Indian Academy of Sciences (India)

    S Rachna; Surya M Gupta; S Bhattacharyya

    2008-09-01

    AC impedance spectroscopy technique has been used to study electrical properties of Bi3.25La0.75Ti3O12 (BLT) ceramic. Complex impedance plots were fitted with three depressed semicircles, which are attributed to crystalline layer, plate boundary and grain boundary and all three were found to comprise of universal capacitance nature [ = 0−1]. Grain boundary resistance and capacitance evaluated from complex impedance plots have larger values than that of plate boundary and crystalline layer. The activation energies (a) for DC-conductance in grain boundary, plate boundary and crystalline layer are 0.68 eV, 0.89 eV and 0.89 eV, respectively. Relaxation activation energies calculated from impedance plots showed similar values, 0.81 eV and 0.80 eV for crystalline layer and plate boundary, respectively. These activation energy values are found to be consistent with the a value of oxygen vacancies in perovskite materials. A mechanism is offered to explain the generation of oxygen vacancies in BLT ceramic and its role in temperature dependence of DC-conductance study.

  4. Bioelectrical signal processing in cardiac and neurological applications and electromyography: physiology, engineering, and noninvasive applications

    Directory of Open Access Journals (Sweden)

    Valentinuzzi Max E

    2007-07-01

    Full Text Available Abstract The present article reviews two recent books dealing with rather closely related subjects; in fact, they tend to complement and supplement reciprocally. Obviously, the electromyogram is a bioelectrical signal that often is mathematically manipulated in different ways to better extract its information. Moreover, its correlation with other bioelectric variables may become necessary.

  5. Bioelectrical signal processing in cardiac and neurological applications and electromyography: physiology, engineering, and noninvasive applications

    OpenAIRE

    Valentinuzzi Max E

    2007-01-01

    Abstract The present article reviews two recent books dealing with rather closely related subjects; in fact, they tend to complement and supplement reciprocally. Obviously, the electromyogram is a bioelectrical signal that often is mathematically manipulated in different ways to better extract its information. Moreover, its correlation with other bioelectric variables may become necessary.

  6. 基于插入损耗法的噪声源内阻抗建模及误差分析%Noise source impedance modeling and measurement error analysis based on insertion loss method

    Institute of Scientific and Technical Information of China (English)

    史国生; 赵阳; 颜伟; 董颖华; 朱志毅

    2012-01-01

    针对传导电磁干扰滤波器设计中人工电源网络阻抗、噪声源内阻抗、负载阻抗与EMI滤波器的阻抗匹配问题,建立了插入损耗法的误差理论模型及其等效电路.分别分析了串联和并联插入损耗法的测量精度及其系统误差,据此提出了相应的测试条件和测试方法,即当被测阻抗远大于负载阻抗时,采用串联插入损耗法;当被测阻抗远小于负载阻抗时,采用并联插入损耗法;当被测阻抗与负载阻抗相当时,可改变负载阻抗.理论与试验研究表明,该方法在适用范围内能够快速有效地提取EMI噪声源内阻抗,从而实现噪声源与EMI滤波器之间的最大阻抗适配,为EMI滤波器的设计及传导电磁干扰噪声抑制提供理论依据.%In order to solve the impedance matching problem for conducted EMI filter designing of artificial mains network (AMN) impedance, noise source impedance, load impedance and EMI filter impedance, the error theoretical model and equivalent circuits of insertion loss (IL) method were established. The measurement accuracy and system error of series and parallel IL methods were analyzed to provide improved test condition and methods. Series IL method was used when the measured impedance was much larger than load impedance. Parallel IL method was utilized when the measured impedance was much smaller than load impedance. The load impedance was altered when the measured impedance approximately equaled to load impedance. Theoretical analysis and experimental results show that the proposed method can extract EMI noise impedance effectively in certain range, where it can also realize the maximum impedance adapter between noise impedance and EMI filter. The proposed method has good validity for EMI filter design and conducted EMI noise suppression.

  7. Active impedance matching of complex structural systems

    Science.gov (United States)

    Macmartin, Douglas G.; Miller, David W.; Hall, Steven R.

    1991-01-01

    Viewgraphs on active impedance matching of complex structural systems are presented. Topics covered include: traveling wave model; dereverberated mobility model; computation of dereverberated mobility; control problem: optimal impedance matching; H2 optimal solution; statistical energy analysis (SEA) solution; experimental transfer functions; interferometer actuator and sensor locations; active strut configurations; power dual variables; dereverberation of complex structure; dereverberated transfer function; compensators; and relative power flow.

  8. Analysis of dye-sensitized solar cells with current collecting electrodes using electrochemical impedance spectroscopy, with a finite element method

    Science.gov (United States)

    Shitanda, Isao; Inoue, Kazuya; Hoshi, Yoshinao; Itagaki, Masayuki

    2014-02-01

    The internal resistances of dye-sensitized solar cells (DSCs) with and without current collecting electrodes (CCEs) were analyzed using electrochemical impedance spectroscopy (EIS) with a finite element method (FEM). Three different DSC models with or without current collecting electrodes were designed. Theoretical values of the internal resistance were estimated by FEM on changing the position and size of the current collecting electrodes. Large DSCs with current collecting electrodes were fabricated using a screen-printing technique, and experimental values of the internal resistance were analyzed by EIS and compared with the theoretical values. The internal resistances obtained from the impedance measurements were in good agreement with those obtained by simulation. The internal resistance was found to decrease with increasing width and thickness of the CCEs, below a threshold value. EIS was found to be extremely useful for evaluating CCE design for improved DSCs.

  9. Wavelet-based multiscale analysis of bioimpedance data measured by electric cell-substrate impedance sensing for classification of cancerous and normal cells

    Science.gov (United States)

    Das, Debanjan; Shiladitya, Kumar; Biswas, Karabi; Dutta, Pranab Kumar; Parekh, Aditya; Mandal, Mahitosh; Das, Soumen

    2015-12-01

    The paper presents a study to differentiate normal and cancerous cells using label-free bioimpedance signal measured by electric cell-substrate impedance sensing. The real-time-measured bioimpedance data of human breast cancer cells and human epithelial normal cells employs fluctuations of impedance value due to cellular micromotions resulting from dynamic structural rearrangement of membrane protrusions under nonagitated condition. Here, a wavelet-based multiscale quantitative analysis technique has been applied to analyze the fluctuations in bioimpedance. The study demonstrates a method to classify cancerous and normal cells from the signature of their impedance fluctuations. The fluctuations associated with cellular micromotion are quantified in terms of cellular energy, cellular power dissipation, and cellular moments. The cellular energy and power dissipation are found higher for cancerous cells associated with higher micromotions in cancer cells. The initial study suggests that proposed wavelet-based quantitative technique promises to be an effective method to analyze real-time bioimpedance signal for distinguishing cancer and normal cells.

  10. Stability Analysis of Three-Phase AC Power Systems Based on Measured D-Q Frame Impedances

    OpenAIRE

    Wen, Bo

    2015-01-01

    Small-signal stability is of great concern for distributed power systems with a large number of regulated power converters. These converters are constant-power loads (CPLs) exhibit a negative incremental input resistance within the output voltage regulation bandwidth. In the case of dc systems, design requirements for impedances that guarantee stability have been previously developed and are used in the design and specification of these systems. In terms of three-phase ac systems, a mathemati...

  11. Bioelectricity production from various wastewaters through microbial fuel cell technology

    Directory of Open Access Journals (Sweden)

    Abhilasha S Mathuriya

    2009-12-01

    Full Text Available Microbial fuel cell technology is a new type of renewable and sustainable technology for electricity generation since it recovers energy from renewable materials that can be difficult to dispose of, such as organic wastes and wastewaters. In the present contribution we demonstrated electricity production by beer brewery wastewater, sugar industry wastewater, dairy wastewater, municipal wastewater and paper industry wastewater. Up to 14.92 mA current and 90.23% COD removal was achieved in 10 days of operation. Keywords: Bioelectricity, COD, Microbial Fuel Cells, Wastewater Received: 12 November 2009 / Received in revised form: 30 November 2009, Accepted: 30 November 2009, Published online: 10 March 2010

  12. Analyzing Impedance Spectroscopy Results

    Institute of Scientific and Technical Information of China (English)

    Yoed Tsur; Sioma Baltianski

    2006-01-01

    In this contribution we briefly discuss several analysis techniques for impedance spectroscopy experiments. A number of different approaches, which differ even by the definition of the problem, are used in the literature. Some aimed towards finding an equivalent circuit. Others aimed towards finding directly dielectric properties of the material under an assumed model. Others towards finding distribution of relaxation times, either parametric or point-by point. No matter what the approach is, this will always be an ill-posed problem in the sense that there exist a large number of possible solutions that solve the problem (mathematically) equally well. Therefore some a-priori knowledge about the system must be used. In addition, we should remember that the ultimate goal is to get physical insight about the system.

  13. Wakefields and coupling impedances

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Superconducting Super Collider Laboratory, 2550 Beckleymeade Ave., Dallas, Texas 75237 (United States))

    1995-02-01

    After a short introduction of the wake potentials and coupling impedances, a few new results in impedance calculations are discussed. The first example is a new analytical method for calculating impedances of axisymmetric structures in the low frequency range, below the cutoff frequency of the vacuum chamber. The second example demonstrates that even very small discontinuities on a smooth waveguide can result in appearance of trapped modes, with frequencies slightly below the waveguide cutoff frequency. The high-frequency (above the cutoff) behavior of the coupling impedance of many small discontinuities is discussed in the third example. [copyright] 1995 [ital American] [ital Institute] [ital of] [ital Physics

  14. Wakefields and coupling impedances

    Science.gov (United States)

    Kurennoy, Sergey

    1995-02-01

    After a short introduction of the wake potentials and coupling impedances, a few new results in impedance calculations are discussed. The first example is a new analytical method for calculating impedances of axisymmetric structures in the low frequency range, below the cutoff frequency of the vacuum chamber. The second example demonstrates that even very small discontinuities on a smooth waveguide can result in appearance of trapped modes, with frequencies slightly below the waveguide cutoff frequency. The high-frequency (above the cutoff) behavior of the coupling impedance of many small discontinuities is discussed in the third example.

  15. Impedance model for nanostructures

    Directory of Open Access Journals (Sweden)

    R. S. Akhmedov

    2007-06-01

    Full Text Available The application of the impedance model for nanoelectronic quantum-mechanical structures modelling is described. Characteristics illustrating the efficiency of the model are presented.

  16. [Approaches to reduce the retroaction of long-term monitoring of bioelectric events in ergonomic field studies (author's transl)].

    Science.gov (United States)

    Zipp, P; Faber, S

    1979-10-01

    When monitoring bioelectric signals the surface electrodes can cause a retroaction on the subject thereby introducing an error of measurement. There are two types of retroaction: physical and psycho-physiological. A physical retroaction due to the hydration process of the skin occurs if 'wet' electrodes are used for the recording of the skin conductance level (SCL) causing a continuous drift of the SCL and a decrease in sensitivity to SCL changes. Therefore a dry electrode was developed with improved performance: It exhibits less sensitivity to motion, is not subject to polarization, and features better SCL long-term stability. When recording the electrocardiogram or the electromyogram a psychophysiological retroaction occurs due to the annoyance caused by the skin-irritating abrading techniques in order to decrease the skin impedance and reduce the motion artifact. In an attempt to abandon the skin preparation whenever permissible without sacrificing the measurement accuracy a performance estimation procedure was developed. Basing on the information on the signal frequency content, the electrode contact area, the required accuracy of measurement and the amplifier input impedance a decision on the necessity of skin preparation is made. Moreover, the results of a study are reported investigating the reduction of motion artifacts by means of electrode design and appropriate electrode jelly formulation.

  17. Bioelectrical Regulation of Cell Cycle and the Planarian Model System

    Science.gov (United States)

    Barghouth, Paul G.; Thiruvalluvan, Manish; Oviedo, Néstor J.

    2015-01-01

    Cell cycle regulation through the manipulation of endogenous membrane potentials offers tremendous opportunities to control cellular processes during tissue repair and cancer formation. However, the molecular mechanisms by which biophysical signals modulate the cell cycle remain underappreciated and poorly understood. Cells in complex organisms generate and maintain a constant voltage gradient across the plasma membrane known as the transmembrane potential. This potential, generated through the combined efforts of various ion transporters, pumps and channels, is known to drive a wide range of cellular processes such as cellular proliferation, migration and tissue regeneration while its deregulation can lead to tumorigenesis. These cellular regulatory events, coordinated by ionic flow, correspond to a new and exciting field termed molecular bioelectricity. We aim to present a brief discussion on the biophysical machinery involving membrane potential and the mechanisms mediating cell cycle progression and cancer transformation. Furthermore, we present the planarian Schmidtea mediterranea as a tractable model system for understanding principles behind molecular bioelectricity at both the cellular and organismal level. PMID:25749155

  18. Optically Controlled Oscillators in an Engineered Bioelectric Tissue

    Science.gov (United States)

    McNamara, Harold M.; Zhang, Hongkang; Werley, Christopher A.; Cohen, Adam E.

    2016-07-01

    Complex electrical dynamics in excitable tissues occur throughout biology, but the roles of individual ion channels can be difficult to determine due to the complex nonlinear interactions in native tissue. Here, we ask whether we can engineer a tissue capable of basic information storage and processing, where all functional components are known and well understood. We develop a cell line with four transgenic components: two to enable collective propagation of electrical waves and two to enable optical perturbation and optical readout of membrane potential. We pattern the cell growth to define simple cellular ring oscillators that run stably for >2 h (˜104 cycles ) and that can store data encoded in the direction of electrical circulation. Using patterned optogenetic stimulation, we probe the biophysical attributes of this synthetic excitable tissue in detail, including dispersion relations, curvature-dependent wave front propagation, electrotonic coupling, and boundary effects. We then apply the biophysical characterization to develop an optically reconfigurable bioelectric oscillator. These results demonstrate the feasibility of engineering bioelectric tissues capable of complex information processing with optical input and output.

  19. CSR Impedance for Non-Ultrarelativistic Beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Rui [Jefferson Lab., Newport News, VA (United States); Tsai, Cheng Y. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Jefferson Lab., Newport News, VA (United States)

    2015-09-01

    For the analysis of the coherent synchrotron radiation (CSR)-induced microbunching gain in the low energy regime, such as when a high-brightness electron beam is transported through a low-energy merger in an energy-recovery linac (ERL) design, it is necessary to extend the CSR impedance expression in the ultrarelativistic limit to the non-ultrarelativistic regime. This paper presents our analysis of CSR impedance for general beam energies.

  20. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  1. On the impedance of galvanic cells XXI. Analysis of the electrode impedance in the case of a non-reversible electrode reaction with specific adsorption of the electroactive species; appl

    NARCIS (Netherlands)

    Sluyters-Rehbach, M.; Timmer, B.; Sluyters, J.H.

    1967-01-01

    The impedance of the Pb2+/Pb(Hg) electrode has been measured in order to demonstrate the effect of specific adsorption of the electroactive species. The simple randles circuit is not in accordance with the experimental facts and therefore an attempt has been made to interpret them in terms of the th

  2. Surface-charge accumulation effects on open-circuit voltage in organic solar cells based on photoinduced impedance analysis.

    Science.gov (United States)

    Zang, Huidong; Hsiao, Yu-Che; Hu, Bin

    2014-03-14

    The accumulation of dissociated charge carriers plays an important role in reducing the loss occurring in organic solar cells. We find from light-assisted capacitance measurements that the charge accumulation inevitably occurred at the electrode and photovoltaic layer interface for bulk-heterojunction ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al solar cells. Our results indicate, for the first time through impedance measurements, that the charge accumulation exists at the anode side of the device, and more importantly, we successfully identify the type of charge accumulated. Further study shows that the charge accumulation can significantly affect open circuit voltage and short circuit current. As a result, our experimental results from light assisted capacitance measurements provide a new understanding of the loss in open-circuit voltage and short-circuit photocurrent based on charge accumulation. Clearly, controlling charge accumulation presents a new mechanism to improve the photovoltaic performance of organic solar cells.

  3. The Analysis and Structuring of the Causes Impeding the Introduction of Advanced Technologies for Exchange Grain Trading

    Directory of Open Access Journals (Sweden)

    Vinnychenko Olena V

    2015-03-01

    Full Text Available In the article the main causes impeding the development and introduction of advanced technologies for grain trading on commodity exchanges in Ukraine have been identified and structured. The generalization of existing shortcomings in operation of the domestic commodity exchanges has served the basis for the model, within which there were built: a directed graph of correlations between the above mentioned shortcomings in the operation of exchanges, the matrix of dependency and reachability. The causes have been identified and structured, the main ones being determined, which, in turn, makes it possible to carry out the correct sequence of actions and emphasize the primary issues requiring priority solutions at making management decisions in order to promote the grain exchange market. The suggested approach clearly shows the correlation between the existing causes and sequence of their elimination.

  4. Evaluation of back contact in spray deposited SnS thin film solar cells by impedance analysis.

    Science.gov (United States)

    Patel, Malkeshkumar; Ray, Abhijit

    2014-07-01

    The role of back metal (M) contact in sprayed SnS thin film solar cells with a configuration Glass/F:SnO2/In2S3/SnS/M (M = Graphite, Cu, Mo, and Ni) was analyzed and discussed in the present study. Impedance spectroscopy was employed by incorporating constant phase elements (CPE) in the equivalent circuit to investigate the degree of inhomogeneity associated with the heterojunction and M/SnS interfaces. A best fit to Nyquist plot revealed a CPE exponent close to unity for thermally evaporated Cu, making it an ideal back contact. The Bode phase plot also exhibited a higher degree of disorders associated with other M/SnS interfaces. The evaluation scheme is useful for other emerging solar cells developed from low cost processing schemes like spray deposition, spin coating, slurry casting, electrodeposition, etc. PMID:24882468

  5. Analysis of the Impedance Estimation Process of EH4%EH4仪器阻抗估算剖析

    Institute of Scientific and Technical Information of China (English)

    腰善丛

    2012-01-01

    详细讨论了STRATAGEM (EH4)音频大地电磁测量系统资料处理过程中所隐含的重要步骤及其实现过程,特别是由时间序列资料经FFT变换后所产生的原始谱叠加后的频点与其相应的X文件(互功率谱文件)中的频点对应、归属与筛选问题,由X文件形成Z(阻抗)文件时X文件中频点与Z文件中频点的对应、归属与筛选问题.上述问题的解决,为相关研究人员利用该设备所采集资料而开发其他阻抗估算技术提供了基础.%The key steps and performance in the data process of STRAGEM (EH4) system was discussed in details, especially the raw cross-powers caused by the time-serial data's FFT, its stack and the corresponding problems in the X file (the cross-power file) such as frequency reflecting, attribution and sifting, as well as those between X file and Z file (impedance file). The solution to the above problems can provide a basis for the related researcher to develop new impedance estimation technique for the EH4's time-serial data.

  6. Electrical impedance of acupuncture meridians: the relevance of subcutaneous collagenous bands.

    Directory of Open Access Journals (Sweden)

    Andrew C Ahn

    Full Text Available BACKGROUND: The scientific basis for acupuncture meridians is unknown. Past studies have suggested that acupuncture meridians are physiologically characterized by low electrical impedance and anatomically associated with connective tissue planes. We are interested in seeing whether acupuncture meridians are associated with lower electrical impedance and whether ultrasound-derived measures--specifically echogenic collagenous bands--can account for these impedance differences. METHODS/RESULTS: In 28 healthy subjects, we assessed electrical impedance of skin and underlying subcutaneous connective tissue using a four needle-electrode approach. The impedances were obtained at 10 kHz and 100 kHz frequencies and at three body sites - upper arm (Large Intestine meridian, thigh (Liver, and lower leg (Bladder. Meridian locations were determined by acupuncturists. Ultrasound images were obtained to characterize the anatomical features at each measured site. We found significantly reduced electrical impedance at the Large Intestine meridian compared to adjacent control for both frequencies. No significant decrease in impedance was found at the Liver or Bladder meridian. Greater subcutaneous echogenic densities were significantly associated with reduced impedances in both within-site (meridian vs. adjacent control and between-site (arm vs. thigh vs. lower leg analyses. This relationship remained significant in multivariable analyses which also accounted for gender, needle penetration depth, subcutaneous layer thickness, and other ultrasound-derived measures. CONCLUSION/SIGNIFICANCE: Collagenous bands, represented by increased ultrasound echogenicity, are significantly associated with lower electrical impedance and may account for reduced impedances previously reported at acupuncture meridians. This finding may provide important insights into the nature of acupuncture meridians and the relevance of collagen in bioelectrical measurements.

  7. Pilot Impedance Performance Analysis for Transmission Lines with Series Compensation%带串联补偿的输电线路纵联阻抗性能分析

    Institute of Scientific and Technical Information of China (English)

    夏经德; 索南加乐; 罗玲; 梁振锋; 张健康; 何世恩

    2011-01-01

    According to the systematic analysis for performance and impedance value of the transmission line pilot impedance based on the series compensation capacitors, especially for the influences of the different operation modes of the series compensation capacitors and subsidiary metal oxide varistor (MOV), and the discharge gap on the pilot impedance, a discrimination method of the related pilot protection is established. Because the distributed transmission line capacitances and the system operation modes mutually affect the pilot impedance, the necessity of compensation for pilot impedance can be determined via calculation. When the amplitude of the pilot impedance is smaller than the setting value to demonstrate the internal fault, the pilot protection is correctly operated; otherwise the pilot protection is stably be blocked. In the EMTP simulation,an UHV transmission line model of 1 000 kV, 500 km, including the series compensation capacitors of 45% power frequency series compensation degree, is constructed to simulate different types of faults.%在系统分析基于串联补偿电容器下输电线路纵联阻抗性能特点和阻值特征的基础上,特别在详细分析串联补偿电容器及其附属的金属氧化物变阻器(MOV)、放电间隙等不同的运行方式在纵联阻抗产生影响的前提下,确立了纵联保护的甄别方法.由于在串联补偿下输电线路分布电容和系统运行方式共同影响纵联阻抗的阻值,因此通过分析和计算才能确定是否需要补偿.一旦纵联阻抗幅值小于设定数值时,就可确定发生区内故障,保护将正确动作;否则,就断定在保护区内没有发生故障,保护将稳定不动.在EMTP软件的仿真中,建立了一条1 000 kV、500 km含工频串联补偿度为45%串联补偿电容器的特高压输电线路模型,进行了在各种故障下的仿真模拟,仿真结果验证了上述纵联阻抗及其算法在串联补偿环境下具有足够的稳定性和可靠性.

  8. Analysis of electric vehicle charger input impedance%电动汽车充电机输入阻抗特性分析

    Institute of Scientific and Technical Information of China (English)

    李晶; 姜久春; 牛利勇

    2013-01-01

    The problem of interaction between electric car charger and the grid is transformed into the research on charging machine input impedance and the grid output impedance by using the research methods of DC-DC modules interaction. The electric car charger input part is three-phase PWM rectifier, so first the small signal model of three-phase PWM rectifier is established in d-q coordinate system , then the reduced order model is established and its open loop and closed loop input impedance expression are deduced. How the charging machine input impedance vary with the change of the grid voltage is discussed. PWM rectifier output current, inductance parasitic resistance, capacitance parasitic resistance, voltage control loop, and current control loop are researched. The paper can provide a basis for the stability analysis of electric vehicle chargers.%针对电动汽车充电机与电网之间的相互作用问题,借鉴DC/DC模块之间相互作用的研究方法,将充电机与电网之间的相互作用问题转化为研究充电机输入阻抗与电网输出阻抗之间的问题.由于电动汽车充电机的输入部分为三相PWM整流器,在d-q坐标系下建立了降阶的三相PWM整流器小信号模型,推导出其开环与闲环输入阻抗表达式.研究充电机输入阻抗随电网电压波动,PWM整流器输出电流、电感寄生电阻和电容寄生电阻,以及电压控制环路和电流控制环路对输入阻抗的影响.

  9. Impedance and component heating

    CERN Document Server

    Métral, E; Mounet, N; Pieloni, T; Salvant, B

    2015-01-01

    The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.

  10. The LEP impedance model

    Energy Technology Data Exchange (ETDEWEB)

    Zotter, B. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)

  11. Dead-ended anode polymer electrolyte fuel cell stack operation investigated using electrochemical impedance spectroscopy, off-gas analysis and thermal imaging

    Science.gov (United States)

    Meyer, Quentin; Ashton, Sean; Curnick, Oliver; Reisch, Tobias; Adcock, Paul; Ronaszegi, Krisztian; Robinson, James B.; Brett, Daniel J. L.

    2014-05-01

    Dead-ended anode operation, with intermittent purge, is increasingly being used in polymer electrolyte fuel cells as it simplifies the mass flow control of feed and improves fuel efficiency. However, performance is affected through a reduction in voltage during dead-ended operation, particularly at high current density. This study uses electrochemical impedance spectroscopy (EIS), off-gas analysis and high resolution thermal imaging to examine the source of performance decay during dead-ended operation. A novel, 'reconstructed impedance' technique is applied to acquire complete EIS spectra with a temporal resolution that allows the dynamics of cell processes to be studied. The results provide evidence that upon entering dead-ended operation, there is an initial increase in performance associated with an increase in anode compartment pressure and improved hydration of the membrane electrolyte. Subsequent reduction in performance is associated with an increase in mass transport losses due to a combination of water management issues and build-up of N2 in the anode. The purge process rapidly recovers performance. Understanding of the processes involved in the dead-end/purge cycle provides a rationale for determining the optimum cycle frequency and duration as a function of current density.

  12. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.

  13. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Taer, E.; Awitdrus,; Farma, R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Mathematics and Natural Sciences, University of Riau, 28293 Pekanbaru, Riau (Indonesia); Deraman, M., E-mail: madra@ukm.my; Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Kanwal, S. [ICCBS, H.E.J. Research Institute of Chemistry, University of Karachi, 75270 Karachi (Pakistan)

    2015-04-16

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H{sub 2}SO{sub 4} electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g{sup −1} respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g{sup −1}, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  14. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    Science.gov (United States)

    Taer, E.; Deraman, M.; Talib, I. A.; Awitdrus, Farma, R.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R.; Kanwal, S.

    2015-04-01

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H2SO4 electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g-1 respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g-1, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  15. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    International Nuclear Information System (INIS)

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H2SO4 electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g−1 respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g−1, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide

  16. Position dependent analysis of membrane electrode assembly degradation of a direct methanol fuel cell via electrochemical impedance spectroscopy

    Science.gov (United States)

    Hartmann, Peter; Zamel, Nada; Gerteisen, Dietmar

    2013-11-01

    The performance of a direct methanol fuel cell MEA degraded during an operational period of more than 3000 h in a stack is locally examined using electrochemical impedance spectroscopy. Therefore, after disassembling the MEA is cut into small pieces and analyzed in a 1 cm2 test cell. Using a reference electrode, we were capable of measuring the anode and cathode spectra separately. The spectra of the segments at different positions do not follow a specified trend from methanol inlet to outlet of the stack flow field. The anode spectra were analyzed with an equivalent circuit simulation. The conductance of the charge transfer was found to increase with current density up to a point where a raising limitation process of the complex methanol oxidation dominates, which is not a bottleneck at low current density. Further, an increase of the double layer capacitance with current density was observed. The diffusion resistance was calculated as an effective diffusion coefficient in the order of 10-10 m2 s-1; implying that the diffusion limitation is not the bulk diffusion in the backing layer. Finally, the degree of poisoning of the catalysts by carbon monoxide was measured as a pseudo inductive arc and decreases with increasing current.

  17. Evaluation of the Trajectory Sensitivity Analysis of the DFIG Control Parameters in Response to Changes in Wind Speed and the Line Impedance Connection to the Grid DFIG

    Directory of Open Access Journals (Sweden)

    Mehdi Fooladgar

    2015-01-01

    Full Text Available Economic and environmental conditions often make large stations and transmission lines, restrictions are placed. Small and medium-sized production units connected to existing systems as a strategy is in progress. These units are usually near the center of the load placed and distributed generators (DG famous are the DG are allowed types vary, such as induction generators rack squirrel-connected wind turbines, generators fed induction double mounted wind turbines, fuel cells connected to the system by power electronic converters or synchronous generator connected to the turbine combustion [10]. This way sensitivity analysis in systems of distributed generation (DG is assessed. It is shown that the method can detect the effect of control parameters listed wind turbine connected to a double-fed induction generator (DFIG Badoou the impedance of the changing the speed of on the stability of the transmission line useful system invested. The control parameters of the importance of influencing the behavior of DFIG are divided.

  18. Structure, magnetic and complex impedance analysis of (1-x)BaTiO{sub 3}- xMgFe{sub 2}O{sub 4} composite

    Energy Technology Data Exchange (ETDEWEB)

    Zolkepli, M. F. A., E-mail: mifah-30@yahoo.com; Zainuddin, Z., E-mail: zazai@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2015-09-25

    MgFe{sub 2}O{sub 4} was synthesized by using sol-gel auto-combustion technique and coupled with BaTiO{sub 3} using the conventional solid state reaction method with different weight fraction of x = 0.00, 0.02, 0.04, 0.06 and 0.08 to form (1-x)BaTiO{sub 3} - xMgFe{sub 2}O{sub 4} composite. The structure, magnetic properties and complex impedance analysis of the composite samples were studied using X-ray diffraction technique (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) and High-frequency response analyzer (HFRA) respectively. XRD patterns showed a single phase tetragonal BaTiO{sub 3} for each composition due to the very small amount of MgFe{sub 2}O{sub 4}. The hysteresis loop confirmed that the composite has soft magnetic properties by addition of MgFe{sub 2}O{sub 4}. Small coercive field, HC has been recorded and it decreased with the increasing of MgFe{sub 2}O{sub 4} weight fraction. However, magnetization increased when the amount of MgFe{sub 2}O{sub 4} is increased. Impedance analysis conducted in range of 0.1 Hz to 10 MHz showed two depressed semicircle arcs for samples with MgFe{sub 2}O{sub 4} due to the resistive and capacitive behavior of the bulk and grain boundaries of the samples.

  19. Noise analysis in fast magnetic resonance electrical impedance tomography (MREIT) based on spoiled multi gradient echo (SPMGE) pulse sequence

    Science.gov (United States)

    In Oh, Tong; Jeong, Woo Chul; Kim, Ji Eun; Sajib, Saurav Z. K.; Kim, Hyung Joong; In Kwon, Oh; Woo, Eung Je

    2014-08-01

    Magnetic resonance electrical impedance tomography (MREIT) is a promising non-invasive method to visualize a static cross-sectional conductivity and/or current density image by injecting low frequency currents. MREIT measures one component of the magnetic flux density caused by the injected current using a magnetic resonance (MR) scanner. For practical in vivo implementations of MREIT, especially for soft biological tissues where the MR signal rapidly decays, it is crucial to develop a technique for optimizing the magnetic flux density signal by the injected current while maintaining spatial-resolution and contrast. We design an MREIT pulse sequence by applying a spoiled multi-gradient-echo pulse sequence (SPMGE) to the injected current nonlinear encoding (ICNE), which fully injects the current at the end of the read-out gradient. The applied ICNE-SPMGE pulse sequence maximizes the duration of injected current almost up to a repetition time by measuring multiple magnetic flux density data. We analyze the noise level of measured magnetic flux density with respect to the pulse width of injection current and T_{2}^{*} relaxation time. In due consideration of the ICNE-SPMGE pulse sequence, using a reference information of T_{2}^{*} values in a local region of interest by a short pre-scan data, we predict the noise level of magnetic flux density to be measured for arbitrary repetition time TR. Results from phantom experiment demonstrate that the proposed method can predict the noise level of magnetic flux density for an appropriate TR = 40 ms using a reference scan for TR = 75 ms. The predicted noise level was compared with the noise level of directly measured magnetic flux density data.

  20. Hydrodynamic and longitudinal impedance analysis of cerebrospinal fluid dynamics at the craniovertebral junction in type I Chiari malformation.

    Directory of Open Access Journals (Sweden)

    Bryn A Martin

    Full Text Available Elevated or reduced velocity of cerebrospinal fluid (CSF at the craniovertebral junction (CVJ has been associated with type I Chiari malformation (CMI. Thus, quantification of hydrodynamic parameters that describe the CSF dynamics could help assess disease severity and surgical outcome. In this study, we describe the methodology to quantify CSF hydrodynamic parameters near the CVJ and upper cervical spine utilizing subject-specific computational fluid dynamics (CFD simulations based on in vivo MRI measurements of flow and geometry. Hydrodynamic parameters were computed for a healthy subject and two CMI patients both pre- and post-decompression surgery to determine the differences between cases. For the first time, we present the methods to quantify longitudinal impedance (LI to CSF motion, a subject-specific hydrodynamic parameter that may have value to help quantify the CSF flow blockage severity in CMI. In addition, the following hydrodynamic parameters were quantified for each case: maximum velocity in systole and diastole, Reynolds and Womersley number, and peak pressure drop during the CSF cardiac flow cycle. The following geometric parameters were quantified: cross-sectional area and hydraulic diameter of the spinal subarachnoid space (SAS. The mean values of the geometric parameters increased post-surgically for the CMI models, but remained smaller than the healthy volunteer. All hydrodynamic parameters, except pressure drop, decreased post-surgically for the CMI patients, but remained greater than in the healthy case. Peak pressure drop alterations were mixed. To our knowledge this study represents the first subject-specific CFD simulation of CMI decompression surgery and quantification of LI in the CSF space. Further study in a larger patient and control group is needed to determine if the presented geometric and/or hydrodynamic parameters are helpful for surgical planning.

  1. Use of low-frequency electrical impedance measurements to determine phospholipid content in amniotic fluid

    Science.gov (United States)

    DeLuca, F.; Cametti, C.; Zimatore, G.; Maraviglia, B.; Pachi', A.

    1996-09-01

    In this report we propose a new method for an in vitro test of the foetal lung maturity based on the measurement of the electrical conductivity of the overall amniotic fluid obtained from transabdominal amniocentesis, since this quantity can be linked to a first approximation in a very simple way to the phospholipid content. We have carried out measurements of 85 different samples of amniotic fluid as a function of gestation weeks and we have observed a pronounced change of the electrical conductivity that reflects the increase in the phospholipid concentration occurring at the end of normal pregnancies. The method could be further developed to obtain similar information on in vivo experiments by means of bioelectric impedance tomography, taking advantage of the frequency dependence of the tissue electrical impedance.

  2. Endogenous bioelectrical networks store non-genetic patterning information during development and regeneration.

    Science.gov (United States)

    Levin, Michael

    2014-06-01

    Pattern formation, as occurs during embryogenesis or regeneration, is the crucial link between genotype and the functions upon which selection operates. Even cancer and aging can be seen as challenges to the continuous physiological processes that orchestrate individual cell activities toward the anatomical needs of an organism. Thus, the origin and maintenance of complex biological shape is a fundamental question for cell, developmental, and evolutionary biology, as well as for biomedicine. It has long been recognized that slow bioelectrical gradients can control cell behaviors and morphogenesis. Here, I review recent molecular data that implicate endogenous spatio-temporal patterns of resting potentials among non-excitable cells as instructive cues in embryogenesis, regeneration, and cancer. Functional data have implicated gradients of resting potential in processes such as limb regeneration, eye induction, craniofacial patterning, and head-tail polarity, as well as in metastatic transformation and tumorigenesis. The genome is tightly linked to bioelectric signaling, via ion channel proteins that shape the gradients, downstream genes whose transcription is regulated by voltage, and transduction machinery that converts changes in bioelectric state to second-messenger cascades. However, the data clearly indicate that bioelectric signaling is an autonomous layer of control not reducible to a biochemical or genetic account of cell state. The real-time dynamics of bioelectric communication among cells are not fully captured by transcriptomic or proteomic analyses, and the necessary-and-sufficient triggers for specific changes in growth and form can be physiological states, while the underlying gene loci are free to diverge. The next steps in this exciting new field include the development of novel conceptual tools for understanding the anatomical semantics encoded in non-neural bioelectrical networks, and of improved biophysical tools for reading and writing

  3. Dielectric, ferroelectrics properties and impedance spectroscopy analysis of the [(Na0.535K0.480)0.966Li0.058](Nb0.90Ta0.10)O3-based lead-free ceramics

    Science.gov (United States)

    Saidi, M.; Chaouchi, A.; D'Astorg, S.; Rguiti, M.; Courtois, C.

    2015-04-01

    Polycrystalline of [(Na0.535K0.480)0.966Li0.058](Nb0.90Ta0.10)O3 samples were prepared using the high-temperature solid-state reaction technique. X-ray diffraction (XRD) analysis indicates the formation of a single-phase with orthorhombic structure. AC impedance plots were used as tool to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The AC impedance studies revealed the presence of grain effect, from 425°C onwards. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) characteristic of NKLNT. The AC conductivity results were used to correlate with the barrier hopping (CBH) model to evaluate the binding energy (Wm), the minimum hopping distance (Rmin), the density of states at Fermi level (N(Ef)), and the activation energy of the compound.

  4. Impedance modelling of pipes

    Science.gov (United States)

    Creasy, M. Austin

    2016-03-01

    Impedance models of pipes can be used to estimate resonant frequencies of standing waves and model acoustic pressure of closed and open ended pipes. Modelling a pipe with impedance methods allows additional variations to the pipe to be included in the overall model as a system. Therefore an actuator can be attached and used to drive the system and the impedance model is able to include the dynamics of the actuator. Exciting the pipe system with a chirp signal allows resonant frequencies to be measured in both the time and frequency domain. The measurements in the time domain are beneficial for introducing undergraduates to resonances without needing an understanding of fast Fourier transforms. This paper also discusses resonant frequencies in open ended pipes and how numerous texts incorrectly approximate the resonant frequencies for this specific pipe system.

  5. Impeded Dark Matter

    CERN Document Server

    Kopp, Joachim; Slatyer, Tracy R; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider a new class of thermal dark matter models, dubbed "Impeded Dark Matter", in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. We demonstrate that either case can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppress...

  6. Impedance spectroscopic and dielectric analysis of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rouahi, A. [Grenoble Electrical Engineering Laboratory (G2E Lab), CNRS, University of Grenoble (UJF), 25 Rue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Laboratory of Materials, Organization and Properties (LMOP), Campus Universities, El Manar, 2092 Tunis (Tunisia); Kahouli, A., E-mail: kahouli.kader@yahoo.fr [Grenoble Electrical Engineering Laboratory (G2E Lab), CNRS, University of Grenoble (UJF), 25 Rue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Laboratory of Materials, Organization and Properties (LMOP), Campus Universities, El Manar, 2092 Tunis (Tunisia); Sylvestre, A., E-mail: alain.sylvestre@grenoble.cnrs.fr [Grenoble Electrical Engineering Laboratory (G2E Lab), CNRS, University of Grenoble (UJF), 25 Rue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France); Defaye, E. [CEA-LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Yangui, B. [Laboratory of Materials, Organization and Properties (LMOP), Campus Universities, El Manar, 2092 Tunis (Tunisia)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer The material exhibits the contribution of both grain and grain boundaries in the electric response of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3}. Black-Right-Pointing-Pointer The plot of normalized complex dielectric modulus and impedance as a function of frequency exhibits both short and long-range conduction in the film. Black-Right-Pointing-Pointer The frequency dependence of ac conductivity exhibits a polaron hopping mechanism with activation energy of 0.38 eV. Black-Right-Pointing-Pointer The complex dielectric modulus analysis confirmed the presence of a non-Debye type of conductivity relaxation deduced from the KWW function. - Abstract: Polycrystalline Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin film with Pt/BST/Pt/TiO{sub 2}/SiO{sub 2} structure was prepared by ion beam sputtering. The film was post annealed at 700 Degree-Sign C. The dielectric and electric modulus properties were studied by impedance spectroscopy over a wide frequency range [0.1-10{sup 5} Hz] at different temperatures [175-350 Degree-Sign C]. The Nyquist plots (Z Double-Prime vs . Z Prime ) show the contribution of both grain and grain boundaries at higher temperature on the electric response of BST thin films. Moreover, the resistance of grains decreases with the rise in temperature and the material exhibits a negative temperature coefficient of resistance. The electric modulus plot indicates the non-Debye type of dielectric relaxation. The values of the activation energy computed from both plots of Z Double-Prime and M Double-Prime are 0.86 eV and 0.81 eV respectively, which reveals that the species responsible for conduction are the same. The scaling behavior of M{sup Double-Prime }/M{sup Double-Prime }{sub max} shows the temperature independent nature of relaxation time. The plot of normalized complex dielectric modulus and impedance as a function of frequency exhibits both short and long-range conduction in the film.

  7. HTPEM Fuel Cell Impedance

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg

    potentially play an important role in the energy system of the future. One of the fuel cell technologies, that receives much attention from the Danish scientific community is high temperature proton exchange membrane (HTPEM) fuel cells based on polybenzimidazole (PBI) with phosphoric acid as proton conductor...... cells through experimental studies and mathematical modelling. These studies all revolve around the electrochemical impedance spectroscopy (EIS) characterisation method. EIS is performed by applying a sinusoidal current or voltage signal to the fuel cell and calculating the impedance from the response...

  8. Impedance analysis of oxygen reduction in Au nanoparticles; Analisis por impedancia de la reduccion de oxigeno sobre nanoparticulas de Au

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez-Huerta, G.; Ramos-Sanchez, G. [Cinvestav-IPN, Mexico, D.F. (Mexico)]. E-mail: gervazkez@gmail.com; Antano-Lopez, R. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica S. C., Pedro Escobedo, Queretaro (Mexico); Solorza-Feria, O. [Cinvestav-IPN, Mexico, D.F. (Mexico)

    2009-09-15

    Nanometric-sized ({approx}5nm) Au particles were synthesized using the chemical reduction of AuCl{sub 3} with NaBH{sub 4}. The Au particles were analyzed with x-ray diffraction (XRD), finding that the particles are highly crystalline, with a face-centered cubic (FCC) structure. The impedance spectrums obtained in 0.5M H{sub 2}SO{sub 4} solution saturated with O{sub 2}, at potentials greater than 0.38 V vs NHE, show one single temperature constant associated with the reduction in O{sub 2} on Au particles, producing hydrogen peroxide (O{sub 2} +2H{sup +} + 2e{sup -} =H{sub 2}O{sub 2}). At potentials less than 0.38 V, a second constant temperature appears associated with a second process, that is, the reduction of H{sub 2}O{sub 2} to H{sub 2}O. [Spanish] Particulas de Au con tamano nanometrico ({approx}5nm) fueron sintetizadas a partir de la reduccion quimica del AuCl{sub 3} con NaBH{sub 4}. Las particulas de Au fueron analizadas con difraccion de rayos X (XRD), se encontro que las particulas son altamente cristalinas, con una estructura cubica centrada en las caras (FCC). Los espectros de impedancia obtenidos en solucion 0.5M H{sub 2}SO{sub 4} saturada con O{sub 2}, a potenciales mayores de 0.38 V vs NHE muestran una sola constante de tiempo, asociada a la reduccion de O{sub 2} sobre las particulas de Au, dando como producto peroxido de hidrogeno (O{sub 2} +2H{sup +} + 2e{sup -} =H{sub 2}O{sub 2}). A potenciales menores de 0.38 V aparece una segunda constante de tiempo, asociada a un segundo proceso, i.e. la reduccion del H{sub 2}O{sub 2} a H{sub 2}O.

  9. In-situ oxide layer analysis of alloy 182 using electrochemical impedance spectroscopy in high dissolved hydrogen condition in PWR environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho-Sub; Subramanian, Gokul Obulan; Hong, Jong-Dae; Lee, Junho; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    Alloy 82/182 weld metals had been extensively used in joining the components of the PWR primary system. Unfortunately, the cracking caused by PWSCC usually occurs on Alloy 82/182 dissimilar metal welds (DMW). Previous studies indicated that the susceptibility of PWSCC is closely related to the oxide characteristics which are dependent on water chemistry condition, especially dissolved hydrogen (DH). Furthermore, in primary system of pressurized water reactor (PWR), crack initiation resulted from electrochemical instability of oxide film of Ni-base structural materials in various hydrogen concentrations. In this study, in-situ oxide analysis of Alloy 182 using electrochemical impedance spectroscopy (EIS) was performed in high dissolved hydrogen condition. Especially, to understand the effects of tensile loading on the oxide characteristics, we tried to characterize the oxides formed on the tensile loaded specimen using in-situ EIS analysis. The EIS analysis of oxide on Alloy 182 was performed. The increase of oxide film thickness was observed with the increase of exposure time. To analysis the multi-layer structure of oxides, an equivalent model was obtained by fitting EIS data. It is assumed that overall oxide structures were composed of 3 layers approximately.

  10. A review of impedance measurements of whole cells.

    Science.gov (United States)

    Xu, Youchun; Xie, Xinwu; Duan, Yong; Wang, Lei; Cheng, Zhen; Cheng, Jing

    2016-03-15

    Impedance measurement of live biological cells is widely accepted as a label free, non-invasive and quantitative analytical method to assess cell status. This method is easy-to-use and flexible for device design and fabrication. In this review, three typical techniques for impedance measurement, i.e., electric cell-substrate impedance sensing, Impedance flow cytometry and electric impedance spectroscopy, are reviewed from the aspects of theory, to electrode design and fabrication, and applications. Benefiting from the integration of microelectronic and microfluidic techniques, impedance sensing methods have expanded their applications to nearly all aspects of biology, including living cell counting and analysis, cell biology research, cancer research, drug screening, and food and environmental safety monitoring. The integration with other techniques, the fabrication of devices for certain biological assays, and the development of point-of-need diagnosis devices is predicted to be future trend for impedance sensing techniques. PMID:26513290

  11. ANÁLISIS EN EL PLANO R-X PARA LOCALIZAR FALLAS DE ALTA IMPEDANCIA R-X AXIS ANALYSIS TO LOCATE HIGH IMPEDANCE FAULTS

    Directory of Open Access Journals (Sweden)

    Germán Andrés Morales-España

    2009-08-01

    Full Text Available Este artículo propone una herramienta de análisis en el plano R-X de un sistema en falla para resolver el problema de localización de fallas en sistemas de potencia. La herramienta permite localizar todo tipo de fallas incluidas las de alta impedancia y fallas en sistemas con sobrecarga. Metodológicamente, se analiza el plano R-X de la impedancia aparente de las fases involucradas en la falla, y utilizando interpolación bidimensional se logra la ubicación de la falla a partir de curvas de distancia previamente obtenidas del sistema mediante simulación. Como resultados se presentan pruebas en un sistema de referencia sometido a los cuatro tipos de falla con diversas resistencias localizadas en diferentes sitios dentro del sistema, resaltándose la obtención de errores inferiores al 3% para fallas monofásicas y resistencia de falla hasta 1000[Ω].This paper proposes an analysis tool using the R-X axis of a faulted system to solve the fault location problem in power systems. The proposed approach allows locating all types of faults including high impedance ones and faults on overload systems. Methodologically, the apparent impedance R-X axis of faulted phases is analyzed and the fault is located from distance curves, previously obtained from the power system, by using two-dimensional interpolation. As results, tests of a reference system with four types of faults and different fault resistances located on different places on the system are presented. Errors are kept lower than 3% for single phase faults and fault resistances up to 1000[Ω].

  12. Molecular bioelectricity: how endogenous voltage potentials control cell behavior and instruct pattern regulation in vivo.

    Science.gov (United States)

    Levin, Michael

    2014-12-01

    In addition to biochemical gradients and transcriptional networks, cell behavior is regulated by endogenous bioelectrical cues originating in the activity of ion channels and pumps, operating in a wide variety of cell types. Instructive signals mediated by changes in resting potential control proliferation, differentiation, cell shape, and apoptosis of stem, progenitor, and somatic cells. Of importance, however, cells are regulated not only by their own Vmem but also by the Vmem of their neighbors, forming networks via electrical synapses known as gap junctions. Spatiotemporal changes in Vmem distribution among nonneural somatic tissues regulate pattern formation and serve as signals that trigger limb regeneration, induce eye formation, set polarity of whole-body anatomical axes, and orchestrate craniofacial patterning. New tools for tracking and functionally altering Vmem gradients in vivo have identified novel roles for bioelectrical signaling and revealed the molecular pathways by which Vmem changes are transduced into cascades of downstream gene expression. Because channels and gap junctions are gated posttranslationally, bioelectrical networks have their own characteristic dynamics that do not reduce to molecular profiling of channel expression (although they couple functionally to transcriptional networks). The recent data provide an exciting opportunity to crack the bioelectric code, and learn to program cellular activity at the level of organs, not only cell types. The understanding of how patterning information is encoded in bioelectrical networks, which may require concepts from computational neuroscience, will have transformative implications for embryogenesis, regeneration, cancer, and synthetic bioengineering. PMID:25425556

  13. Comparison of total body water estimates from O-18 and bioelectrical response prediction equations

    Science.gov (United States)

    Barrows, Linda H.; Inners, L. Daniel; Stricklin, Marcella D.; Klein, Peter D.; Wong, William W.; Siconolfi, Steven F.

    1993-01-01

    Identification of an indirect, rapid means to measure total body water (TBW) during space flight may aid in quantifying hydration status and assist in countermeasure development. Bioelectrical response testing and hydrostatic weighing were performed on 27 subjects who ingested O-18, a naturally occurring isotope of oxygen, to measure true TBW. TBW estimates from three bioelectrical response prediction equations and fat-free mass (FFM) were compared to TBW measured from O-18. A repeated measures MANOVA with post-hoc Dunnett's Test indicated a significant (p less than 0.05) difference between TBW estimates from two of the three bioelectrical response prediction equations and O-18. TBW estimates from FFM and the Kushner & Schoeller (1986) equation yielded results that were similar to those given by O-18. Strong correlations existed between each prediction method and O-18; however, standard errors, identified through regression analyses, were higher for the bioelectrical response prediction equations compared to those derived from FFM. These findings suggest (1) the Kushner & Schoeller (1986) equation may provide a valid measure of TBW, (2) other TBW prediction equations need to be identified that have variability similar to that of FFM, and (3) bioelectrical estimates of TBW may prove valuable in quantifying hydration status during space flight.

  14. The Characteristic States of the Magnetotelluric Impedance Tensor: Construction, Analytic Properties and Utility in the Analysis of General Earth Conductivity Distributions

    CERN Document Server

    Tzanis, Andreas

    2014-01-01

    It is shown that the Magnetotelluric (MT) impedance tensor admits an anti-symmetric generalized eigenvalue - eigenstate decomposition consistent with the anti-symmetry of electric and magnetic fields referred to the same coordinate frame: this is achieved by anti-diagonalization through rotation by 2x2 complex operators of the SU(2) rotation group. The eigenstates comprise simple proportional relationships between linearly polarized eigenvalues of the input magnetic and output electric field along the locally resistive and conductive propagation path into the Earth, respectively mediated by the maximum and minimum characteristic values of the tensor (eigen-impedances). It is shown from first principles that the eigen-impedances are expected to be positive real (passive) functions, analytic in the entire lower-half complex frequency plane and with singularities confined on the positive imaginary frequency axis. Insofar as the impedance tensor is generated by isometric transformation of the eigen-impedances, it...

  15. Implantable Impedance Plethysmography

    Directory of Open Access Journals (Sweden)

    Michael Theodor

    2014-08-01

    Full Text Available We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term.

  16. Microbiology and optimization of hydrogen fermentation and bioelectricity production

    Energy Technology Data Exchange (ETDEWEB)

    Makinen, A.

    2013-11-01

    This work investigated dark fermentative hydrogen (H{sub 2}) and bioelectricity production from carbohydrates. Meso- and thermophilic fermentative and mesophilic exoelectrogenic bacteria were enriched from different natural sources. The H{sub 2} production from different hexoses and pentoses, them main constituents of lignocellulose, was studied in batch assays. H{sub 2} production from xylose was examined in continuous stirred tank reactor (CSTR). Operational parameters for H{sub 2} production were optimized. Bioelectricity production was studied in microbial fuel cells and process parameters were optimized. Dynamics of microbial communities in H{sub 2} and bioelectricity production processes were determined. A novel thermophilic dark fermentative H{sub 2} producing bacterium, Thermovorax subterraneus, was enriched and isolated from geothermal underground mine. T. subterraneus had the optimum growth temperature of 72 deg C and the maximum H{sub 2} yield of 1.4 mol/mol glucose in batch assay. The main soluble fermentative end products of T. subterraneus were acetate and ethanol. Thermophilic dark fermentative mixed culture enriched from hot spring (Hisarlan, Turkey) had the maximum H{sub 2} yield of 1.7 mol/mol glucose. The optimal environmental parameters to maximize H{sub 2} yield were temperature 52 deg C, initial pH 6.5, 40 mg/L Fe{sup 2+}, 4.5 g/L yeast extract and glucose concentration of 4 g/L. Increasing the glucose concentration to 18 g/L increased the maximum H{sub 2} production rate to 56.2 mmol H{sub 2}/h/L. Environmental parameters had a significant effect on metabolic pathways of fermentation. Another hot spring (Hisarkoy, Turkey) enrichment culture was able to ferment different sugars to H{sub 2} favoring pentoses over hexoses. The best H{sub 2} yields in batch assays were obtained from pentoses: xylose, arabinose and ribose yielded 21, 15 and 8 % of the theoretical yield, respectively; whilst on glucose the yield was only 2 % of the theoretical

  17. Impedance spectroscopy of food mycotoxins

    Science.gov (United States)

    Bilyy, Oleksandr I.; Yaremyk, Roman Ya.; Kotsyumbas, Ihor Ya.; Kotsyumbas, Halyna I.

    2012-01-01

    A new analytical method of high-selective detection of mycotoxins in food and feed are considered. A method is based on optical registration the changes of conduct of the electric polarized bacterial agents in solution at the action of the external gradient electric fields. Measuring are conducted in integrated electrode-optical cuvette of the special construction, which provides the photometric analysis of forward motion of the objects registration in liquid solution under act of the enclosed electric field and simultaneous registration of kinetics of change of electrical impedance parameters solution and electrode system.

  18. Bioelectricity-assisted partial degradation of linear polyacrylamide in a bioelectrochemical system.

    Science.gov (United States)

    Cui, Yu-Zhi; Zhang, Jian; Sun, Min; Zhai, Lin-Feng

    2015-01-01

    The wide application of water-soluble linear polyacrylamides (PAMs) can cause serious environmental pollution. Biological treatment of PAMs receives very limited efficiency due to their recalcitrance to the microbial degradation. Here, we show the bioelectrochemical system (BES) can be used as an effective strategy to improve the biodegradation efficiency of PAMs. A linear PAM with viscosity-average molecular weight of 5 × 10(6) was treated in the anodic chamber of BES reactor, and the change of PAM structure during the degradation process was investigated. The anodic bacteria in the BES demonstrated abilities to utilize the PAM as the sole carbon and nitrogen source to generate electricity. Both the anode-attached and planktonic bacteria contributed to the electricity generation, while the anode-attached community exhibited stronger electron transfer ability than the planktonic one. The closed-circuit and open-circuit operations of the BES reactor obtained chemical oxygen demand (COD) removal efficiencies of 32.5 and 7.4 %, respectively, implying the generation of bioelectricity could enhance the biodegradation of PAM. Structure analysis suggested the carbon chain of PAM was partially degraded in the BES, producing polymeric products with lower molecular weight. The microbial cleavage of the carbon chain was proposed to start from the "head-to-head" linkages and end with the formation of ether bonds.

  19. Evoked bioelectrical activity of efferent fibers of the sciatic nerve of white rats in experimental menopause

    Directory of Open Access Journals (Sweden)

    Rodinsky A.G.

    2016-03-01

    Full Text Available The aim of our work was analysis of the bioelectrical activity of efferent fibers of the sciatic nerve in experimental menopause condition. Experiments were performed on 25 female white rats, divided into experimental and control groups. Menopause was modeled by total ovariohysterectomy. In 120 days after modeling we had recorded evoked action potentials of fibers of isolated ventral root L5 induced by stimulation of sciatic nerve with rectangular pulses. Threshold, chronaxia, latency, amplitude and duration of the action potential (AP were analysed. Refractory phenomenon was investigated by applying paired stimuli at intervals of 2 to 20 ms. In the context of long-term hypoestrogenemy threshold of AP appearance was 55,32±7,69%, chronaxy – 115,09±2,67%, latent period – 112,62±1,74% as compared with the control animals (p<0.01. In conditions of paired stimuli applying the amplitude of response to the testing stimulus in animals with ovariohysterectomy at intervals 3 and 4 ms was 61,25±36,45% and 53,48±18,64% (p<0.05 respectively.

  20. AC impedance analysis of ionic and electronic conductivities in electrode mixture layers for an all-solid-state lithium-ion battery

    Science.gov (United States)

    Siroma, Zyun; Sato, Tomohiro; Takeuchi, Tomonari; Nagai, Ryo; Ota, Akira; Ioroi, Tsutomu

    2016-06-01

    The ionic and electronic effective conductivities of an electrode mixture layers for all-solid-state lithium-ion batteries containing Li2Ssbnd P2S5 as a solid electrolyte were investigated by AC impedance measurements and analysis using a transmission-line model (TLM). Samples containing graphite (graphite electrodes) or LiNi0.5Co0.2Mn0.3O2 (NCM electrodes) as the active material were measured under a "substrate | sample | bulk electrolyte | sample | substrate" configuration (ion-electron connection) and a "substrate | sample | substrate" configuration (electron-electron connection). Theoretically, if the electronic resistance is negligibly small, which is the case with our graphite electrodes, measurement with the ion-electron connection should be effective for evaluating ionic conductivity. However, if the electronic resistance is comparable to the ionic resistance, which is the case with our NCM electrodes, the results with the ion-electron connection may contain some inherent inaccuracy. In this report, we theoretically and practically demonstrate the advantage of analyzing the results with the electron-electron connection, which gives both the ionic and electronic conductivities. The similarity of the behavior of ionic conductivity with the graphite and NCM electrodes confirms the reliability of this analysis.

  1. Impedance calculation for ferrite inserts

    Energy Technology Data Exchange (ETDEWEB)

    Breitzmann, S.C.; Lee, S.Y.; /Indiana U.; Ng, K.Y.; /Fermilab

    2005-01-01

    Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

  2. Impeded Dark Matter

    OpenAIRE

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider a new class of thermal dark matter models, dubbed "Impeded Dark Matter", in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. We demonstrate that either case can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonst...

  3. 电阻抗分析在菊苣根冻害检测中的应用研究%Application of Electrical Impedance Analysis to Assessment of Freezing Injury in Chicory Roots

    Institute of Scientific and Technical Information of China (English)

    陈发河; MauiceDeProft

    2002-01-01

    以菊苣(Cichorium intybus L var foliosum cv.)根为试材,分析了低温下电阻抗和钾离子渗漏速率的变化及其与细胞膜透性变化的定量关系.结果表明:随着低温贮藏时间的延长和冻害的发展,菊苣根细胞膜透性增大,钾离子渗漏速率上升,组织的电阻抗值下降.3种温度下(0℃,-1℃,-3℃)贮藏的菊苣根其电阻抗值的变化均与钾离子渗漏速率呈显著的负相关关系.电阻抗对频率作图显示,在低频率范围(20~100 Hz)可得到最大而且较稳定的电阻抗值.因此,电阻抗分析方法可以用来检测和评价植物的冻害.%Chicory (Cichorium intybus L var foliosum cv.) root was used to investigate the change in electrical impedance and potassium ion leakage during cold storage, and some quantitative relations between the electrical impedance and cell membrane permeability. It is showed that the cell membrane permeability, and the rate of potassium ion leakage increase, while the electrical impedance decreases with the development of freezing injury in chicory root. The change in electrical impedance in chicory roots stored at 0℃, -1℃, -3℃ was remarkable negatively correlated with the potassium ion leakage rate. At low frequency there was relatively little change and the highest value in impedance (20~100 Hz). Therefore, it is feasible that the electrical impedance analysis can be used to estimate the freezing injury of plant.

  4. [Effect of refeeding on the body composition of females with restrictive anorexia nervosa; anthropometry versus bioelectrical impedance].

    Science.gov (United States)

    de Mateo Silleras, Beatriz; Redondo del Río, Paz; Camina Martín, Alicia; Soto Célix, María; Alonso Torre, Sara R; Miján de la Torre, Alberto

    2013-01-01

    Objetivo: Evaluar la composición corporal en un grupo de pacientes desnutridas con anorexia nerviosa, respecto de controles sanas, antes y después del soporte nutricional, mediante antropometría y bioimpedancia. Métodos: Estudio observacional prospectivo. Se realizó una antropometría completa y un análisis de bioimpedancia a 12 mujeres con anorexia nerviosa restrictiva (24,5 años) al ingreso hospitalario y semanalmente durante la realimentación. El grupo control estuvo formado por 24 mujeres sanas (21 años). Se aplicaron los test t-Student, U-Mann-Whitney, t-Student para medidas repetidas o Wilcoxon. La concordancia entre antropometría y BIA se analizó mediante el coeficiente de correlación intraclase y Bland-Altman. Resultados: Las pacientes mejoraron significativamente todos los índices de composición corporal a lo largo de la estancia hospitalaria, aunque sus valores al alta siguieron siendo menores que los de las controles. La media de peso ganado fue 5,22 kg (DE: 1,42), de los que el 51,4% fueron masa grasa, con distribución central preferentemente. En las controles la ecuación de BIA que mejor concuerda con antropometría es la de Sun (CCI = 0,896); en las pacientes la concordancia fue más débil, al ingreso y al alta. Conclusiones: La realimentación produce una ganancia ponderal, fundamentalmente a expensas de masa grasa, con distribución central; no se consigue restablecer el estado nutricional. La concordancia entre antropometría y bioimpedancia para el estudio de la composición corporal es aceptable, especialmente en sujetos sanos. Se recomienda emplear antropometría, si no se dispone de BIA vectorial o algún método gold estandard para el análisis de la composición corporal, en casos de alteraciones importantes en la composición corporal y/o el balance hídrico.

  5. The Detection of Gastric Emptying with Bioelectrical Impedance%基于阻抗法的胃排空检测

    Institute of Scientific and Technical Information of China (English)

    王伟; 任超世; 李章勇; 魏进民

    2008-01-01

    胃排空功能是胃动力研究的主要内容之一,但临床缺乏经济、简单、易重复的检测方法.本文基于阻抗法进行胃排空检测研究,利用小波技术重构胃阻抗信号后快速获得了光滑的胃排空曲线,实现了半排空时间的准确计算.24例健康学生400ml纯净水的半排空时间为8.78±1.76min.

  6. Orthogonal Transformation in Bioelectrical Impedance Measurement%生物电阻抗测量中的正交变换

    Institute of Scientific and Technical Information of China (English)

    李镐炜; 董秀珍; 王跃科; 史学涛; 付峰

    2007-01-01

    探求生物电阻抗测量中,欧姆电阻和等效容抗间的数量关系.基于Cole-Cole阻抗模型,采用Cauchy积分公式进行了理论分析,并用多组实验数据对理论分析结果进行验证.验证实验结果在频率域的大部分范围内与理论分析结果一致.研究结果表明:生物电阻抗测量中,欧姆电阻和等效容抗之间存在确定的正交变换关系.

  7. Agreement between Omron 306 and Biospace InBody 720 Bioelectrical Impedance Analyzers (BIA) in Children and Adolescents

    Science.gov (United States)

    Finn, Kevin J.; Saint-Maurice, Pedro F.; Karsai, István; Ihász, Ferenc; Csányi, Tamás

    2015-01-01

    Purpose: The purpose of this study was to test the convergent validity of Omron 306 using Biospace InBody 720. Method: A total of 267 participants (145 boys; aged 10.4-17.9 years) completed testing during a single session. Each measure provided percent body fat (%BF), while the InBody 720 included fat-free mass (FFM). The validity was examined…

  8. Gynecologic electrical impedance tomograph

    Science.gov (United States)

    Korjenevsky, A.; Cherepenin, V.; Trokhanova, O.; Tuykin, T.

    2010-04-01

    Electrical impedance tomography extends to the new and new areas of the medical diagnostics: lungs, breast, prostate, etc. The feedback from the doctors who use our breast EIT diagnostic system has induced us to develop the 3D electrical impedance imaging device for diagnostics of the cervix of the uterus - gynecologic impedance tomograph (GIT). The device uses the same measuring approach as the breast imaging system: 2D flat array of the electrodes arranged on the probe with handle is placed against the body. Each of the 32 electrodes of the array is connected in turn to the current source while the rest electrodes acquire the potentials on the surface. The current flows through the electrode of the array and returns through the remote electrode placed on the patient's limb. The voltages are measured relative to another remote electrode. The 3D backprojection along equipotential surfaces is used to reconstruct conductivity distribution up to approximately 1 cm in depth. Small number of electrodes enables us to implement real time imaging with a few frames per sec. rate. The device is under initial testing and evaluation of the imaging capabilities and suitability of usage.

  9. Correlation between birth weight and maternal body composition.

    LENUS (Irish Health Repository)

    Kent, Etaoin

    2013-01-01

    To estimate which maternal body composition parameters measured using multifrequency segmental bioelectric impedance analysis in the first trimester of pregnancy are predictors of increased birth weight.

  10. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  11. Characterization of PMN-PT piezoelectric single crystal and PMN-PT 1-3 composite at elevated temperatures by electrical impedance resonance analysis.

    Science.gov (United States)

    Wu, Zhengbin; Xi, Kui

    2014-07-01

    In this paper, lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal and its 1-3 composite counterpart were characterized and analyzed under different stable temperatures using both a Simulated Annealing (SA) optimization algorithm and the commercial software PRAP (Piezoelectric Resonance Analysis Program). Electrical impedance resonance characteristics of the two material samples over the range 25-125 °C were measured. The correlation between experimental data and numerical fits derived from both SA and PRAP is considered. Calculation of the determination coefficient (R1(2)) between numerically fitted and measured results is above 95% for both methods. Furthermore, variations in the number of data values used for the fit introduced no more than 3.1% uncertainty on the calculated material parameters. It is found that the complex material parameters of PMN-PT composite are more dependent on temperature than the single crystal. The phase transition of the PMN-PT, which is close to 90 °C, has an effect on the high temperature material characteristics of both piezoelectric materials. These calculated complex material parameters can be used for the design of ultrasonic transducers for elevated temperature applications.

  12. Determination of ammonium in Kjeldahl digests by gas-diffusion flow-injection analysis with a bulk acoustic wave-impedance sensor.

    Science.gov (United States)

    Su, X L; Nie, L H; Yao, S Z

    1997-11-01

    A novel flow-injection analysis (FIA) system has been developed for the rapid and direct determination of ammonium in Kjeldahl digests. The method is based on diffusion of ammonia across a PTFE gas-permeable membrane from an alkaline (NaOH/EDTA) stream into a stream of diluted boric acid. The trapped ammonium in the acceptor is determined on line by a bulk acoustic wave (BAW)-impedance sensor and the signal is proportional to the ammonium concentration present in the digests. The proposed system exhibits a favorable frequency response to 5.0 x 10(-6)-4.0 x 10(-3) mol l(-1) ammonium with a detection limit of 1.0 x 10(-6) mol l(-1), and the precision was better than 1% (RSD) for 0.025-1.0 mM ammonium at a through-put of 45-50 samples h(-1). Results obtained for nitrogen determination in amino acids and for proteins determination in blood products are in good agreement with those obtained by the conventional distillation/titration method, respectively. The effects of composition of acceptor stream, cell constant of conductivity electrode, sample volume, flow rates and potential interferents on the FIA signals were discussed in detail.

  13. Characterization of PMN-PT piezoelectric single crystal and PMN-PT 1-3 composite at elevated temperatures by electrical impedance resonance analysis.

    Science.gov (United States)

    Wu, Zhengbin; Xi, Kui

    2014-07-01

    In this paper, lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal and its 1-3 composite counterpart were characterized and analyzed under different stable temperatures using both a Simulated Annealing (SA) optimization algorithm and the commercial software PRAP (Piezoelectric Resonance Analysis Program). Electrical impedance resonance characteristics of the two material samples over the range 25-125 °C were measured. The correlation between experimental data and numerical fits derived from both SA and PRAP is considered. Calculation of the determination coefficient (R1(2)) between numerically fitted and measured results is above 95% for both methods. Furthermore, variations in the number of data values used for the fit introduced no more than 3.1% uncertainty on the calculated material parameters. It is found that the complex material parameters of PMN-PT composite are more dependent on temperature than the single crystal. The phase transition of the PMN-PT, which is close to 90 °C, has an effect on the high temperature material characteristics of both piezoelectric materials. These calculated complex material parameters can be used for the design of ultrasonic transducers for elevated temperature applications. PMID:24495996

  14. Electrolyte ion adsorption and charge blocking effect at the hematite/aqueous solution interface: an electrochemical impedance study using multivariate data analysis.

    Science.gov (United States)

    Shimizu, K; Nyström, J; Geladi, P; Lindholm-Sethson, B; Boily, J-F

    2015-05-01

    A model-free multivariate analysis using singular value decomposition is employed to refine an equivalent electrical circuit model in order to probe the electrochemical properties of the hematite/water interface in dilute NaCl and NH4Cl solutions using electrochemical impedance spectroscopy. The result shows that the surface protonation is directly related to the mobility and trapping of charge carriers at the mineral surface. Moreover, the point of zero charge can be found at pH where the charge transfer resistance is the highest, in addition to the minimum double layer capacitance. The inner-sphere interaction of the NH4(+) ion with the surface is indicated by an increase of capacitance for charge carrier trapping from the protonated surface as well as lower double layer capacitance and open circuit potential. It is clear that the intrinsic electrochemical activity of hematite depends on the degree of surface (de)protonation and other inner-sphere adsorption, as these processes affect the charge carrier density in the surface state. This work also highlights an important synergistic effect of the two spectral analyses that enables EIS to be utilized in an in-depth investigation of mineral/water interfaces. PMID:25857599

  15. X-ray photoelectron spectroscopic and electrochemical impedance spectroscopic analysis of RuO2-Ta2O5 thick film pH sensors.

    Science.gov (United States)

    Manjakkal, Libu; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Socha, Robert P; Szwagierczak, Dorota

    2016-08-10

    The paper reports on investigation of the pH sensing mechanism of thick film RuO2-Ta2O5 sensors by using X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Interdigitated conductimetric pH sensors were screen printed on alumina substrates. The microstructure and elemental composition of the films were examined by scanning electron microscopy and energy dispersive spectroscopy. The XPS studies revealed the presence of Ru ions at different oxidation states and the surface hydroxylation of the sensing layer increasing with increasing pH. The EIS analysis carried out in the frequency range 10 Hz-2 MHz showed that the electrical parameters of the sensitive electrodes in the low frequency range were distinctly dependent on pH. The charge transfer and ionic exchange occurring at metal oxide-solution interface were indicated as processes responsible for the sensing mechanism of thick film RuO2-Ta2O5 pH sensors. PMID:27282750

  16. X-ray photoelectron spectroscopic and electrochemical impedance spectroscopic analysis of RuO2-Ta2O5 thick film pH sensors.

    Science.gov (United States)

    Manjakkal, Libu; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Socha, Robert P; Szwagierczak, Dorota

    2016-08-10

    The paper reports on investigation of the pH sensing mechanism of thick film RuO2-Ta2O5 sensors by using X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Interdigitated conductimetric pH sensors were screen printed on alumina substrates. The microstructure and elemental composition of the films were examined by scanning electron microscopy and energy dispersive spectroscopy. The XPS studies revealed the presence of Ru ions at different oxidation states and the surface hydroxylation of the sensing layer increasing with increasing pH. The EIS analysis carried out in the frequency range 10 Hz-2 MHz showed that the electrical parameters of the sensitive electrodes in the low frequency range were distinctly dependent on pH. The charge transfer and ionic exchange occurring at metal oxide-solution interface were indicated as processes responsible for the sensing mechanism of thick film RuO2-Ta2O5 pH sensors.

  17. Iterative Reconstruction Methods for Hybrid Inverse Problems in Impedance Tomography

    DEFF Research Database (Denmark)

    Hoffmann, Kristoffer; Knudsen, Kim

    2014-01-01

    For a general formulation of hybrid inverse problems in impedance tomography the Picard and Newton iterative schemes are adapted and four iterative reconstruction algorithms are developed. The general problem formulation includes several existing hybrid imaging modalities such as current density...... impedance imaging, magnetic resonance electrical impedance tomography, and ultrasound modulated electrical impedance tomography, and the unified approach to the reconstruction problem encompasses several algorithms suggested in the literature. The four proposed algorithms are implemented numerically in two...... be based on a theoretical analysis of the underlying inverse problem....

  18. Impedance of the PEP-II DIP screen

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.-K. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T.

    1996-08-01

    The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances. (author)

  19. Bioelectricity-AQA, one of the first MOOC courses in engineering.

    Science.gov (United States)

    Barr, Roger C

    2014-01-01

    Bioelectricity-AQA was one of the first massively open online courses in engineering, having been given the first time via Coursera starting in September, 2012. This report provides some detail on its background, presentation, enrollment, and lessons learned. PMID:25570327

  20. Evidence of potential averaging over the finite surface of a bioelectric surface electrode.

    NARCIS (Netherlands)

    Dijk, J.P. van; Lowery, M.M.; Lapatki, B.; Stegeman, D.F.

    2009-01-01

    Most bioelectric signals are not only functions of time but also exhibit a variation in spatial distribution. Surface EMG signals are often "summarized" by a large electrode. The effect of such an electrode is interpreted as averaging the potential at the surface of the skin beneath the electrode. W

  1. Bioelectricity production from paper industry waste using a microbial fuel cell by Clostridium species

    Directory of Open Access Journals (Sweden)

    Abhilasha S Mathuriya

    2008-12-01

    cellulosic waste was utilized for the bioelectricity production by Clostridium acetobutylicum and Clostridium thermohydrosulfuricum. Keywords: Bacteria, Clostridium acetobutylicum, Clostridium thermohydrosulfuricum, Electricity, Microbial fuel cell. Received: 28 January 2009 / Received in revised form: 5 February 2009, Accepted: 5 February 2009, Published online: 25 February 2009

  2. The Evaluation of Bioelectrical Activity of Pelvic Floor Muscles Depending on Probe Location: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Tomasz Halski

    2013-01-01

    Full Text Available Objectives. The main objective was to determine how the depth of probe placement affects functional and resting bioelectrical activity of the PFM and whether the recorded signal might be dependent on the direction in which the probe is rotated. Participants. The study comprised of healthy, nulliparous women between the ages of 21 and 25. Outcome Measures. Bioelectric activity of the PFM was recorded from four locations of the vagina by surface EMG and vaginal probe. Results. There were no statistically significant differences between the results during functional sEMG activity. During resting sEMG activity, the highest bioelectrical activity of the PFM was observed in the L1 and the lowest in the L4 and a statistically significant difference between the highest and the lowest results of resting sEMG activity was observed (P=0.0043. Conclusion. Different electrodes placement during functional contraction of PFM does not affect the obtained results in sEMG evaluation. In order to diagnose the highest resting activity of PFM the recording plates should be placed toward the anterior vaginal wall and distally from the introitus. However, all of the PFM have similar bioelectrical activity and it seems that these muscles could be treated as a single muscle.

  3. Impedance group summary

    Science.gov (United States)

    Blaskiewicz, M.; Dooling, J.; Dyachkov, M.; Fedotov, A.; Gluckstern, R.; Hahn, H.; Huang, H.; Kurennoy, S.; Linnecar, T.; Shaposhnikova, E.; Stupakov, G.; Toyama, T.; Wang, J. G.; Weng, W. T.; Zhang, S. Y.; Zotter, B.

    1999-12-01

    The impedance working group was charged to reply to the following 8 questions relevant to the design of high-intensity proton machines such as the SNS or the FNAL driver. These questions were first discussed one by one in the whole group, then each ne of them assigned to one member to summarize. On the lst morning these contributions were publicly read, re-discussed and re-written where required—hence they are not the opinion of a particular person, but rather the averaged opinion of all members of the working group. (AIP)

  4. Photovoltaic Characterization and Electrochemical Impedance Spectroscopy Analysis of Dye-Sensitized Solar Cells Based on Composite TiO2-MWCNT Photoelectrodes

    Science.gov (United States)

    Parvazian, E.; Karimzadeh, F.; Enayati, M. H.

    2014-05-01

    Dye-sensitized solar cells (DSSCs) use the effect of light on dye molecules to generate electricity through a photoelectrochemical mechanism. The aim of this study is to synthesize nanostructured DSSCs based on titania-multiwalled carbon nanotube (TiO2-MWCNT) composite photoelectrodes and improve their performance and efficiency. DSSCs were fabricated based on single-layer TiO2-MWCNT photoelectrodes with various weight percentages of multiwalled carbon nanotubes and bilayer TiO2/TiO2-2%MWCNT photoelectrodes. The microstructure and thickness of the anodic layers were characterized by field-emission scanning electron microscopy and optical microscopy. Also, to compare the conversion efficiency and determine the electron behavior in the electrical equivalent circuit of these cells, photovoltaic characterization and electrochemical impedance spectroscopy (EIS) analysis were used. The DSSC based on a single-layer TiO2-2%MWCNT electrode, compared with other single-layer DSSCs in this study, had the highest conversion efficiency of 3.9% (for anodic layer thickness of 9 μm). The efficiency of the solar cell with the bilayer TiO2/TiO2-2%MWCNT photoelectrode, in comparison with the single-layer solar cell with the TiO2-2%MWCNT electrode, showed a 23% increase from 4.33% to 5.35% (for anodic layer thickness of 18 μm). EIS analysis indicated that the charge-transport resistance of the DSSC based on the bilayer photoelectrode, in comparison with the single-layer TiO2 and TiO2-2%MWCNT solar cells, was decreased by 68% and 57%, respectively.

  5. Isocratic and gradient impedance plot analysis and comparison of some recently introduced large size core-shell and fully porous particles.

    Science.gov (United States)

    Vanderheyden, Yoachim; Cabooter, Deirdre; Desmet, Gert; Broeckhoven, Ken

    2013-10-18

    The intrinsic kinetic performance of three recently commercialized large size (≥4μm) core-shell particles packed in columns with different lengths has been measured and compared with that of standard fully porous particles of similar and smaller size (5 and 3.5μm, respectively). The kinetic performance is compared in both absolute (plot of t0 versus the plate count N or the peak capacity np for isocratic and gradient elution, respectively) and dimensionless units. The latter is realized by switching to so-called impedance plots, a format which has been previously introduced (as a plot of t0/N(2) or E0 versus Nopt/N) and has in the present study been extended from isocratic to gradient elution (where the impedance plot corresponds to a plot of t0/np(4) versus np,opt(2)/np(2)). Both the isocratic and gradient impedance plot yielded a very similar picture: the clustered impedance plot curves divide into two distinct groups, one for the core-shell particles (lowest values, i.e. best performance) and one for the fully porous particles (highest values), confirming the clear intrinsic kinetic advantage of core-shell particles. If used around their optimal flow rate, the core-shell particles displayed a minimal separation impedance that is about 40% lower than the fully porous particles. Even larger gains in separation speed can be achieved in the C-term regime.

  6. Two-dimensional modeling of a polymer electrolyte membrane fuel cell with long flow channel. Part II. Physics-based electrochemical impedance analysis

    Science.gov (United States)

    Bao, Cheng; Bessler, Wolfgang G.

    2015-03-01

    The state-of-the-art electrochemical impedance spectroscopy (EIS) calculations have not yet started from fully multi-dimensional modeling. For a polymer electrolyte membrane fuel cell (PEMFC) with long flow channel, the impedance plot shows a multi-arc characteristic and some impedance arcs could merge. By using a step excitation/Fourier transform algorithm, an EIS simulation is implemented for the first time based on the full 2D PEMFC model presented in the first part of this work. All the dominant transient behaviors are able to be captured. A novel methodology called 'configuration of system dynamics', which is suitable for any electrochemical system, is then developed to resolve the physical meaning of the impedance spectra. In addition to the high-frequency arc due to charge transfer, the Nyquist plots contain additional medium/low-frequency arcs due to mass transfer in the diffusion layers and along the channel, as well as a low-frequency arc resulting from water transport in the membrane. In some case, the impedance spectra appear partly inductive due to water transport, which demonstrates the complexity of the water management of PEMFCs and the necessity of physics-based calculations.

  7. Synthesis of adaptive impedance control for bipedal robot mechanisms

    Directory of Open Access Journals (Sweden)

    Petrović Milena

    2008-01-01

    Full Text Available The paper describes the impedance algorithm in locomotion of humanoid robot with proposed parameter modulation depending on the gate phase. The analysis shows influence of walking speed and foot elevation on regulator's parameters. Chosen criterion cares for footpath tracking and needed energy for that way of walking. The experiments give recommendation for impedance regulator tuning.

  8. Solving the forward problem in electrical impedance tomography for the human head using IDEAS (integrated design engineering analysis software), a finite element modelling tool.

    Science.gov (United States)

    Bayford, R H; Gibson, A; Tizzard, A; Tidswell, T; Holder, D S

    2001-02-01

    If electrical impedance tomography is to be used as a clinical tool, the image reconstruction algorithms must yield accurate images of impedance changes. One of the keys to producing an accurate reconstructed image is the inclusion of prior information regarding the physical geometry of the object. To achieve this, many researchers have created tools for solving the forward problem by means of finite element methods (FEMs). These tools are limited, allowing only a set number of meshes to be produced from the geometric information of the object. There is a clear need for geometrical accurate FEM models to improve the quality of the reconstructed images. We present a commercial tool called IDEAS, which can be used to create FEM meshes for these models. The application of this tool is demonstrated by using segmented data from the human head to model impedance changes inside the head.

  9. FFT-impedance spectroscopy analysis of the growth of magnetic metal nanowires in ultra-high aspect ratio InP membranes

    Science.gov (United States)

    Gerngross, M.-D.; Carstensen, J.; Föll, H.; Adelung, R.

    2016-01-01

    This paper reports on the characterization of the electrochemical growth process of magnetic nanowires in ultra-high-aspect ratio InP membranes via in situ fast Fourier transform impedance spectroscopy in a typical frequency range from 75 Hz to 18.5 kHz. The measured impedance data from the Ni, Co, and FeCo can be very well fitted using the same electric equivalent circuit consisting of a series resistance in serial connection to an RC-element and a Maxwell element. The impedance data clearly indicate the similarities in the growth behavior of Ni, Co and FeCo nanowires in ultra-high aspect ratio InP membranes—the beneficial impact of boric acid on the metal deposition in ultra-high aspect ratio membranes and the diffusion limitation of boric acid, as well as differences such as passivation or side reactions.

  10. Microwave Impedance Measurement for Nanoelectronics

    Directory of Open Access Journals (Sweden)

    M. Randus

    2011-04-01

    Full Text Available The rapid progress in nanoelectronics showed an urgent need for microwave measurement of impedances extremely different from the 50Ω reference impedance of measurement instruments. In commonly used methods input impedance or admittance of a device under test (DUT is derived from measured value of its reflection coefficient causing serious accuracy problems for very high and very low impedances due to insufficient sensitivity of the reflection coefficient to impedance of the DUT. This paper brings theoretical description and experimental verification of a method developed especially for measurement of extreme impedances. The method can significantly improve measurement sensitivity and reduce errors caused by the VNA. It is based on subtraction (or addition of a reference reflection coefficient and the reflection coefficient of the DUT by a passive network, amplifying the resulting signal by an amplifier and measuring the amplified signal as a transmission coefficient by a common vector network analyzer (VNA. A suitable calibration technique is also presented.

  11. [Cardiac output monitoring by impedance cardiography in cardiac surgery].

    Science.gov (United States)

    Shimizu, H; Seki, S; Mizuguchi, A; Tsuchida, H; Watanabe, H; Namiki, A

    1990-04-01

    The cardiac output monitoring by impedance cardiography, NCCOM3, was evaluated in adult patients (n = 12) who were subjected to coronary artery bypass grafting. Values of cardiac output measured by impedance cardiography were compared to those by the thermodilution method. Changes of base impedance level used as an index of thoracic fluid volume were also investigated before and after cardiopulmonary bypass (CPB). Correlation coefficient (r) of the values obtained by thermodilution with impedance cardiography was 0.79 and the mean difference was 1.29 +/- 16.9 (SD)% during induction of anesthesia. During the operation, r was 0.83 and the mean difference was -14.6 +/- 18.7%. The measurement by impedance cardiography could be carried out through the operation except when electro-cautery was used. Base impedance level before CPB was significantly lower as compared with that after CPB. There was a negative correlation between the base impedance level and central venous pressure (CVP). No patients showed any signs suggesting lung edema and all the values of CVP, pulmonary artery pressure and blood gas analysis were within normal ranges. From the result of this study, it was concluded that cardiac output monitoring by impedance cardiography was useful in cardiac surgery, but further detailed examinations will be necessary on the relationship between the numerical values of base impedance and the clinical state of the patients. PMID:2362347

  12. Conversion of orange peel waste biomass to bioelectricity using a mediator-less microbial fuel cell.

    Science.gov (United States)

    Miran, Waheed; Nawaz, Mohsin; Jang, Jiseon; Lee, Dae Sung

    2016-03-15

    Microorganisms have the potential to become a game-changer in sustainable energy production in the coming generations. Microbial fuel cells (MFCs) as an alternative renewable technology can capture bioenergy (electricity) from carbon-based sources by utilizing microorganisms as biocatalysts. This study demonstrated that MFC technology can be explored for bioelectricity production from orange peel waste (OPW), an agricultural byproduct and an organic substrate, without any chemical pretreatment or the addition of extra mediators. A maximum voltage generation of 0.59 ± 0.02 V (at 500 Ω) was achieved in a dual chamber MFC during stable voltage generation stages. The maximum power density and current density obtained were 358.8 ± 15.6 mW/m(2) and 847 ± 18.4 mA/m(2), respectively. Key components of OPW, namely pectin and cellulose, were also tested in their pure form, with pectin giving a stable current, while no significant current generation was achieved using cellulose alone as the substrate, thus demonstrating the absence of cellulose-degrading bacteria. Maximum pectinase and polygalacturonase enzyme activities of 18.55 U/g and 9.04 U/g (per gram of substrate), respectively were achieved during orange peel degradation in MFCs. Bacterial identification using 16S rRNA analysis of the initial inoculum fed to the MFC, the biofilm attached to the anode, and the anode suspension, showed significant diversity in community composition. A well-known exoelectrogen, Pseudomonas, was present among the predominant genera in the anode biofilm. PMID:26780146

  13. Optically stimulated differential impedance spectroscopy

    Science.gov (United States)

    Maxey, Lonnie C; Parks, II, James E; Lewis, Sr., Samuel A; Partridge, Jr., William P

    2014-02-18

    Methods and apparatuses for evaluating a material are described. Embodiments typically involve use of an impedance measurement sensor to measure the impedance of a sample of the material under at least two different states of illumination. The states of illumination may include (a) substantially no optical stimulation, (b) substantial optical stimulation, (c) optical stimulation at a first wavelength of light, (d) optical stimulation at a second wavelength of light, (e) a first level of light intensity, and (f) a second level of light intensity. Typically a difference in impedance between the impedance of the sample at the two states of illumination is measured to determine a characteristic of the material.

  14. Buck-Boost Impedance Networks

    DEFF Research Database (Denmark)

    Goh, Ailian; Gao, Feng; Loh, Pon Chiang;

    2007-01-01

    control, and push up the overall system costs. Therefore, alternative topological solutions are of interest, and should preferably be implemented using only passive LC elements and diodes, connected as unique impedance networks. A number of possible network configurations are now investigated...... in this paper, and are respectively named as Z-source, H-source, EZ-source and their respective "inverted" variants. The presented impedance networks can either be used with a traditional voltage-source or current-source inverter, and can either be powered by a voltage or current source. All impedance networks...... the practicalities and performances of the described impedance networks....

  15. Electrical impedance characterization of normal and cancerous human hepatic tissue.

    Science.gov (United States)

    Laufer, Shlomi; Ivorra, Antoni; Reuter, Victor E; Rubinsky, Boris; Solomon, Stephen B

    2010-07-01

    The four-electrode method was used to measure the ex vivo complex electrical impedance of tissues from 14 hepatic tumors and the surrounding normal liver from six patients. Measurements were done in the frequency range 1-400 kHz. It was found that the conductivity of the tumor tissue was much higher than that of the normal liver tissue in this frequency range (from 0.14 +/- 0.06 S m(-1) versus 0.03 +/- 0.01 S m(-1) at 1 kHz to 0.25 +/- 0.06 S m(-1) versus 0.15 +/- 0.03 S m(-1) at 400 kHz). The Cole-Cole models were estimated from the experimental data and the four parameters (rho(0), rho(infinity), alpha, f(c)) were obtained using a least-squares fit algorithm. The Cole-Cole parameters for the cancerous and normal liver are 9 +/- 4 Omega m(-1), 2.2 +/- 0.7 Omega m(-1), 0.5 +/- 0.2, 140 +/- 103 kHz and 50 +/- 28 Omega m(-1), 3.2 +/- 0.6 Omega m(-1), 0.64 +/- 0.04, 10 +/- 7 kHz, respectively. These data can contribute to developing bioelectric applications for tissue diagnostics and in tissue treatment planning with electrical fields such as radiofrequency tissue ablation, electrochemotherapy and gene therapy with reversible electroporation, nanoscale pulsing and irreversible electroporation.

  16. Modern Trends in Imaging XI: Impedance Measurements in the Biomedical Sciences

    Directory of Open Access Journals (Sweden)

    Frederick D. Coffman

    2012-01-01

    Full Text Available Biological organisms and their component organs, tissues and cells have unique electrical impedance properties. Impedance properties often change with changes in structure, composition, and metabolism, and can be indicative of the onset and progression of disease states. Over the past 100 years, instruments and analytical methods have been developed to measure the impedance properties of biological specimens and to utilize these measurements in both clinical and basic science settings. This chapter will review the applications of impedance measurements in the biomedical sciences, from whole body analysis to impedance measurements of single cells and cell monolayers, and how cellular impedance measuring instruments can now be used in high throughput screening applications.

  17. Experimental Analysis of the Effects of CO and CO2 on High Temperature PEM Fuel Cell Performance using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Vang, Jakob Rabjerg

    2010-01-01

    of fuel cells offer many advantages, particularly the increased desorption rate of CO on the anode catalyst. In order to evaluate the impact of CO and CO2 on the dynamic performance of the HTPEM fuel cell, electrochemical impedance spectroscopy (EIS) has been implemented in Labview, and used on BASF...

  18. Analysis of three-phase inverter small signal input impedance%三相逆变器小信号输入阻抗特性研究

    Institute of Scientific and Technical Information of China (English)

    郑先成; 王文光; 黄沈

    2015-01-01

    Based on the important significance of three-phase inverter input impedance characteristics while analyzing the stability of power system and controlling the power quality. This paper gives the small signal model of three-phase inverter and deduce the impedance expressions of the inverter. The influence on input impedance is analyzed. Then the conclusions are drew: overload is not conducive to the stability of the system; negative impedance characteristics is related to the control parameters, the larger the bandwidth is, the greater the negative impedance characteristics spectrum is;The influence of LC filter parameters on the input impedance of inverters mainly manifests under high frequency conditions. The impedance amplitude increases as the damping ratio enlarges. This paper also puts forward a new idea on inverter design by which the inverter parameters meets all the requirements of system stability. The simulation results show that cascade system comprised of rectifier and inverter is stable.%文中基于三相逆变器输入阻抗特性对于分析电力系统的稳定性和控制电能质量的重要意义,通过小信号建模对三相逆变器的输入阻抗进行了分析,得出以下结论:增加负载不利于系统稳定性;控制参数与维持逆变器输入阻抗负阻抗特性有关,带宽越大,负阻抗特性的频段越宽;而LC滤波器参数对输入阻抗的影响主要体现在高频段,随着阻尼比的增加,其输入阻抗幅值增加。本文还提出一种设计逆变器新思路,即从满足系统稳定性要求出发设计逆变器参数,仿真结果表明,整流器与逆变器级联系统是稳定的。

  19. Effects of various organic carbon sources on simultaneous V(V) reduction and bioelectricity generation in single chamber microbial fuel cells.

    Science.gov (United States)

    Hao, Liting; Zhang, Baogang; Cheng, Ming; Feng, Chuanping

    2016-02-01

    Four ordinary carbon sources affecting V(V) reduction and bioelectricity generation in single chamber microbial fuel cells (MFCs) were investigated. Acetate supported highest maximum power density of 589.1mW/m(2), with highest V(V) removal efficiency of 77.6% during 12h operation, compared with glucose, citrate and soluble starch. Exorbitant initial V(V) concentration led to lower V(V) removal efficiencies and power outputs. Extra addition of organics had little effect on the improvement of MFCs performance. V(V) reduction and bioelectricity generation were enhanced and then suppressed by the increase of conductivity. The larger the external resistance, the higher the V(V) removal efficiencies and voltage outputs. High-throughput 16S rRNA gene pyrosequencing analysis implied the accumulation of Enterobacter which had the capabilities of V(V) reduction, electrochemical activity and fermentation, accompanied with other functional species as Pseudomonas, Spirochaeta, Sedimentibacter and Dysgonomonas. This study steps forward to remediate V(V) contaminated environment based on MFC technology.

  20. Finite difference time domain implementation of surface impedance boundary conditions

    Science.gov (United States)

    Beggs, John H.; Luebbers, Raymond J.; Yee, Kane S.; Kunz, Karl S.

    1991-01-01

    Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In the finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media throughout the solution volume. The standard approach is to approximate the surface impedance over a very small bandwidth by its value at the center frequency, and then use that result in the boundary condition. Here, two implementations of the surface impedance boundary condition are presented. One implementation is a constant surface impedance boundary condition and the other is a dispersive surface impedance boundary condition that is applicable over a very large frequency bandwidth and over a large range of conductivities. Frequency domain results are presented in one dimension for two conductivity values and are compared with exact results. Scattering width results from an infinite square cylinder are presented as a two dimensional demonstration. Extensions to three dimensions should be straightforward.

  1. Plasmonic-Based Electrochemical Impedance Spectroscopy: Application to Molecular Binding

    Science.gov (United States)

    Lu, Jin; Wang, Wei; Wang, Shaopeng; Shan, Xiaonan; Li, Jinghong; Tao, Nongjian

    2012-01-01

    Plasmonic-based electrochemical impedance spectroscopy (P-EIS) is developed to investigate molecular binding on surfaces. Its basic principle relies on the sensitive dependence of surface plasmon resonance (SPR) signal on surface charge density, which is modulated by applying an AC potential to a SPR chip surface. The AC component of the SPR response gives the electrochemical impedance, and the DC component provides the conventional SPR detection. The plasmonic-based impedance measured over a range of frequency is in quantitative agreement with the conventional electrochemical impedance. Compared to the conventional SPR detection, P-EIS is sensitive to molecular binding taking place on the chip surface, and less sensitive to bulk refractive index changes or non-specific binding. Moreover, this new approach allows for simultaneous SPR and surface impedance analysis of molecular binding processes. PMID:22122514

  2. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling...... electrode and 2-D gas transport models which have fewer unknown parameters for the same number of processes, (ii) use of a new model fitting algorithm, “multi-fitting”, in which multiple impedance spectra are fit simultaneously with parameters linked based on the variation of measurement conditions, (iii...

  3. Acoustic impedances of ear canals measured by impedance tube

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2007-01-01

    During hearing sensitivity tests, the sound field is commonly generated by an earphone placed on a subject ear. One of the factors that can affect the sound transmission in the ear is the acoustic impedance of the ear canal. Its importance is related to the contribution of other elements involved...... locations in an impedance tube. The end of the tube representing the measurement plane is placed at the ear canal entrance. Thus, the impedance seen from the entrance inward is measured on 25 subjects. Most subjects participated in the previous measurement of the ratio between the pressures at the open...

  4. A Role for Bioelectric Effects in the Induction of Bystander Signals by Ionizing Radiation?

    OpenAIRE

    Mothersill, C; Moran, G; McNeill, F.; Gow, M.D.; Denbeigh, J.; Prestwich, W.; Seymour, C. B.

    2007-01-01

    The induction of “bystander effects” i.e. effects in cells which have not received an ionizing radiation track, is now accepted but the mechanisms are not completely clear. Bystander effects following high and low LET radiation exposure are accepted but mechanisms are still not understood. There is some evidence for a physical component to the signal. This paper tests the hypothesis that bioelectric or biomagnetic phenomena are involved. Human immortalized skin keratinocytes and primary expla...

  5. An introduction to the memristor - a valuable circuit element in bioelectricity and bioimpedance

    OpenAIRE

    Gorm Krogh Johnsen

    2012-01-01

    The memristor (short for memory resistor) is a yet quite unknown circuit element, though equally fundamental as resistors, capacitors, and coils. It was predicted from theory arguments nearly 40 years ago, but not realized as a physical component until recently. The memristor shows many interesting features when describing electrical phenomena, especially at small (molecular or cellular) scales and can in particular be useful for bioimpedance and bioelectricity modeling. It can also give us a...

  6. In vitro bioelectric properties of bronchial epithelium from transplanted lungs in recipients with cystic fibrosis.

    OpenAIRE

    Tsang, V. T.; Alton, E. W.; Hodson, M E; Yacoub, M

    1993-01-01

    BACKGROUND--Bronchial epithelial function after heart-lung transplantation (HLT) for cystic fibrosis (CF) may be affected by the original disease as well as other factors such as prolonged organ ischaemic time, the interruption of bronchial arterial and lymphatic supply, infection, rejection, and cyclosporin. In vitro measurement of the bioelectric properties of the bronchial mucosal lining may be an effective means of characterising the mucosal function of the lung allografts in response to ...

  7. Endogenous Voltage Potentials and the Microenvironment: Bioelectric Signals that Reveal, Induce and Normalize Cancer

    OpenAIRE

    Chernet, Brook; Levin, Michael

    2013-01-01

    Cancer may be a disease of geometry: a misregulation of the field of information that orchestrates individual cells’ activities towards normal anatomy. Recent work identified molecular mechanisms underlying a novel system of developmental control: bioelectric gradients. Endogenous spatio-temporal differences in resting potential of non-neural cells provide instructive cues for cell regulation and complex patterning during embryogenesis and regeneration. It is now appreciated that these cues a...

  8. Molecular bioelectricity: how endogenous voltage potentials control cell behavior and instruct pattern regulation in vivo

    OpenAIRE

    Levin, Michael

    2014-01-01

    In addition to biochemical gradients and transcriptional networks, cell behavior is regulated by endogenous bioelectrical cues originating in the activity of ion channels and pumps, operating in a wide variety of cell types. Instructive signals mediated by changes in resting potential control proliferation, differentiation, cell shape, and apoptosis of stem, progenitor, and somatic cells. Of importance, however, cells are regulated not only by their own V mem but also by the V mem of their ne...

  9. Bioelectrical activity of limb muscles during cold shivering of stimulation of the vestibular apparatus

    Science.gov (United States)

    Kuzmina, G. I.

    1980-01-01

    The effects of caloric and electric stimulation of the vestibular receptors on the EMG activity of limb muslces in anesthetized cats during cold induced shivering involved flexor muscles alone. Both types of stimulation suppressed bioelectrical activity more effectively in the ipsilateral muscles. The suppression of shivering activity seems to be due to the increased inhibitory effect of descending labyrinth pathways on the function of flexor motoneurons.

  10. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

    OpenAIRE

    Javier Cervera; Antonio Alcaraz; Salvador Mafe

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) th...

  11. Impedance-estimation methods, modeling methods, articles of manufacture, impedance-modeling devices, and estimated-impedance monitoring systems

    Science.gov (United States)

    Richardson, John G.

    2009-11-17

    An impedance estimation method includes measuring three or more impedances of an object having a periphery using three or more probes coupled to the periphery. The three or more impedance measurements are made at a first frequency. Three or more additional impedance measurements of the object are made using the three or more probes. The three or more additional impedance measurements are made at a second frequency different from the first frequency. An impedance of the object at a point within the periphery is estimated based on the impedance measurements and the additional impedance measurements.

  12. Time course of pulmonary vascular response to an acutely repetitive pulmonary microembolism in dogs--an analysis using pulmonary vascular impedance.

    Science.gov (United States)

    Tobise, K; Tosaka, S; Onodera, S

    1992-05-01

    To understand the mechanism leading to progressive pulmonary hypertension, we investigated the time course of vascular response to an acutely repetitive pulmonary microembolism in dogs by using pulmonary vascular impedance. In a normal state, the mean pulmonary arterial pressure (mPAP) was transiently increased by emboli, and the impedance moduli of 0 Hz (= Rin), 1.5 Hz and 3 Hz were slightly increased. A four-element electrical vascular model showed the transient increase in peripheral pulmonary vascular resistance (R2) and inertia, and reduction in compliance (C). In contrast, in a state of a slight pulmonary hypertension, mPAP was continuously increased by the same amount of emboli, and the impedance moduli of both 0 Hz and 3 Hz were significantly increased. By a four-element model, a severe increase in R2 and reduction in C were observed, and these changes continued. Therefore, although the vascular response to pulmonary microembolism basically depends on the degree of mechanical obstruction, this response is thought to be modulated by the responsiveness of pulmonary vessels at that time, which is involved in the alteration in the local characteristics of pulmonary vessels, and/or the recruitment of a new blood flow.

  13. Representation of bioelectric current sources using Whitney elements in the finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Tanzer, I Oguz [Laboratory of Biomedical Engineering, PO Box 2200, 02015 HUT and BioMag Laboratory, Medical Engineering Center (Finland); Jaervenpaeae, Seppo [Electromagnetics Laboratory, PO Box 3000, FIN-02015 HUT (Finland); Nenonen, Jukka [Elekta Neuromag Oy, PO Box 68, FIN-00511 Helsinki (Finland); Somersalo, Erkki [Department of Mathematics, PO Box 1100, FIN-02015 HUT (Finland)

    2005-07-07

    Bioelectric current sources of magneto- and electroencephalograms (MEG, EEG) are usually modelled with discrete delta-function type current dipoles, despite the fact that the currents in the brain are naturally continuous throughout the neuronal tissue. In this study, we represent bioelectric current sources in terms of Whitney-type elements in the finite element method (FEM) using a tetrahedral mesh. The aim is to study how well the Whitney elements can reproduce the potential and magnetic field patterns generated by a point current dipole in a homogeneous conducting sphere. The electric potential is solved for a unit sphere model with isotropic conductivity and magnetic fields are calculated for points located on a cap outside the sphere. The computed potential and magnetic field are compared with analytical solutions for a current dipole. Relative difference measures between the FEM and analytical solutions are less than 1%, suggesting that Whitney elements as bioelectric current sources are able to produce the same potential and magnetic field patterns as the point dipole sources.

  14. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  15. 空气置换法、生物电阻抗法与皮褶厚度法测试身体成分的比较研究%Comparative Study of Air Displacement Plethysmography, Bioelectrical Impedance Analysis and Skinfold Thickness in the Determination of Adult Body Fat Percentage

    Institute of Scientific and Technical Information of China (English)

    金晶; 庄洁; 陈佩杰; 王人卫

    2008-01-01

    目的:探讨生物电阻抗法与皮褶厚度法测定身体成分的结果与空气置换法(BOD-POD)结果的相关性.方法:随机选取20~59岁上海市居民697名(男471名,女226名),以空气置换法测定的身体成分值作为标准,将生物电阻抗法(OMRON与TANITA)和皮褶厚度法(测量部位为上臂部和肩胛部)的结果与之进行单因素方差分析和相关性分析.结果:皮褶厚度法测试结果与空气置换法结果相关性最低;生物电阻抗法中,TANITA测试结果与空气置换法结果相关性最高,OMRON相关性较低.结果提示:生物电阻抗法中TANI-TA测量的可靠性相对较高,皮褶厚度法(测量部位为上臂部和肩胛部)测量的可靠性相对较低.

  16. Realization of a New Segmental Bioelectrical Impedance Method for Assessing Body Composition: Correlation Analysis of Human Body Parameters%一种新的分段生物电阻抗评估人体成分方法的实现:人体参数相关性分析

    Institute of Scientific and Technical Information of China (English)

    肖贵遐; 刘国庆; 李湘荣; 郭云波; 吴建春

    2001-01-01

    用分段生物电阻抗方法评估人体成分需测量人体各段的长度或横截面积,增加了这种方法的复杂性.本文通过分析人体参数间相关性,得到了用性别、身高、体重表示的各段参数的线性回归等式,从而简化了分段阻抗法.

  17. The value of multifrequency bioelectrical impedance analysis on therapy sufficiency estimation in peritoneal dialysis patients%多频生物电阻抗技术在腹膜透析患者透析充分性评估中的价值

    Institute of Scientific and Technical Information of China (English)

    沈芳媛; 包蓓艳

    2012-01-01

    目的 应用多频生物电阻抗分析法(MBIA)评价腹膜透析患者的人体组成,并与腹膜透析充分性(Kt/V)相比较.方法 选择腹膜透析患者76例,按体质指数标准分为消瘦组、正常组、超重肥胖组.采用人体成分分析仪测量体重(WT)、体质指数(BMI)、总体水(TBW)、细胞外液(ECW)、细胞内液(ICW)、脂肪组织(FM)、非脂肪组织(FFM),同时计算尿素清除率(Kt/V).结果 从消瘦组、正常组到超重肥胖组,人体组成各指标逐级递增,各组间比较差异均有高度统计学意义(P<0.01).超重肥胖组Kt/V明显低于正常组(P<0.01).Kt/V与BMI、TBW、ECW、ICW、FM 、FFM均呈负相关(P< 0.05或P< 0.01).结论 不同BMI的腹膜透析患者的人体组成变化明显,MBIA对评估腹膜透析患者体液平衡状态及透析充分性有重要意义.

  18. IMPEDANCE CHARACTERISTICS OF POLYFURAN FILMS

    Institute of Scientific and Technical Information of China (English)

    Liang Li; Xiao-bo Wan; Gi Xue

    2002-01-01

    Electrochemical impedance spectroscopy (EIS) was first used for the characterization of polyfuran (PFu) films that had been formed electrochemically on an Au electrode. The polyfuran was measured in high oxidation state, intermediate oxidation state and reduction state, respectively. As the oxidation level is increased, the ionic conductivity of PFu/BF4-increases. And impedance studies on PFu show that the anion BF4- appears to be mobile with a high diffusion coefficient of approximately 10-8 cm2 @ s-1.

  19. Nickel-ceria infiltrated Nb-doped SrTiO3 for low temperature SOFC anodes and analysis on gas diffusion impedance

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Jacobsen, Torben;

    2012-01-01

    by sintering STN in air and reducing atmosphere, respectively. The porous microstructures were then infiltrated with Ni and Gd-doped CeO2 (CGO) precursors to incorporate the electrocatalytically active sites. The electrochemical performance of the anode was improved with the increment of Ni-CGO loadings....... The gas diffusion impedance was investigated with He and N2 in H2/H2O gas mixtures and by varying the H2O content at 655 °C. This study indicated that the gas diffusion in these electrodes are influenced by Knudsen and bulk diffusion....

  20. Motion discrimination of throwing a baseball using forearm electrical impedance

    International Nuclear Information System (INIS)

    The extroversion or hyperextension of elbow joint cause disorders of elbow joint in throwing a baseball. A method, which is easy handling and to measure motion objectively, can be useful for evaluation of throwing motion. We investigated a possibility of motion discrimination of throwing a baseball using electrical impedance method. The parameters of frequency characteristics (Cole-Cole arc) of forearm electrical impedance were measured during four types of throwing a baseball. Multiple discriminant analysis was used and the independent variables were change ratios of 11 parameters of forearm electrical impedance. As results of 120 data with four types of throwing motion in three subjects, hitting ratio was very high and 95.8%. We can expect to discriminate throwing a baseball using multiple discriminant analysis of impedance parameters.

  1. Motion discrimination of throwing a baseball using forearm electrical impedance

    Science.gov (United States)

    Nakamura, Takao; Kusuhara, Toshimasa; Yamamoto, Yoshitake

    2013-04-01

    The extroversion or hyperextension of elbow joint cause disorders of elbow joint in throwing a baseball. A method, which is easy handling and to measure motion objectively, can be useful for evaluation of throwing motion. We investigated a possibility of motion discrimination of throwing a baseball using electrical impedance method. The parameters of frequency characteristics (Cole-Cole arc) of forearm electrical impedance were measured during four types of throwing a baseball. Multiple discriminant analysis was used and the independent variables were change ratios of 11 parameters of forearm electrical impedance. As results of 120 data with four types of throwing motion in three subjects, hitting ratio was very high and 95.8%. We can expect to discriminate throwing a baseball using multiple discriminant analysis of impedance parameters.

  2. A valveless micro impedance pump driven by electromagnetic actuation

    OpenAIRE

    Rinderknecht, Derek; Hickerson, Anna Iwaniec; Gharib, Morteza

    2005-01-01

    Over the past two decades, a variety of micropumps have been explored for various applications in microfluidics such as control of pico- and nanoliter flows for drug delivery as well as chemical mixing and analysis. We present the fabrication and preliminary experimental studies of flow performance on the micro impedance pump, a previously unexplored method of pumping fluid on the microscale. The micro impedance pump was constructed of a simple thin-walled tube coupled at either end to glass ...

  3. MD 349: Impedance Localization with AC-dipole

    CERN Document Server

    Biancacci, Nicolo; Metral, Elias; Salvant, Benoit; Papotti, Giulia; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2016-01-01

    The purpose of this MD is to measure the distribution of the transverse impedance of the LHC by observing the phase advance variation with intensity between the machine BPMs. Four injected bunches with different intensities are excited with an AC dipole and the turn by turn data is acquired from the BPM system. Through post-processing analysis the phase variation along the machine is depicted and, from this information, first conclusions of the impedance distribution can be drawn.

  4. On the potential of using fractional-order systems to model the respiratory impedance

    Directory of Open Access Journals (Sweden)

    Clara IONESCU

    2006-12-01

    Full Text Available This contribution provides an analysis of the human respiratory system in frequency domain by means of estimating the respiratory impedance. Further on, analysis of several models for human respiratory impedance is done, leading to the conclusion that a fractional model gives a better description of the impedance than the classical theory of integer-order systems. A mathematical analysis follows, starting from the conclusions obtained heuristically. Correlation to the physiological characteristics of the respiratory system is discussed.

  5. On the potential of using fractional-order systems to model the respiratory impedance

    OpenAIRE

    Clara IONESCU; Robin DE KEYSER

    2006-01-01

    This contribution provides an analysis of the human respiratory system in frequency domain by means of estimating the respiratory impedance. Further on, analysis of several models for human respiratory impedance is done, leading to the conclusion that a fractional model gives a better description of the impedance than the classical theory of integer-order systems. A mathematical analysis follows, starting from the conclusions obtained heuristically. Correlation to the physiological characteri...

  6. [Monitoring cervical dilatation by impedance].

    Science.gov (United States)

    Salvat, J; Lassen, M; Sauze, C; Baud, S; Salvat, F

    1992-01-01

    Several different physics procedures have been tried to mechanize the recording of partograms. Can a measure of impedance of tissue Z using potential difference V, according to Ohm's law V = Z1, and 1 is a constant, be correlated with a measure of cervical dilatation using vaginal examination? This was our hypothesis. The tissue impedance meter was made to our design and applied according to a bipolar procedure. Our work was carried out on 28 patients. 10 patients were registered before labour started in order to test the apparatus and to record the impedance variations without labour taking place, and 18 patients were registered in labour to see whether there was any correlation. The level of impedance in the cervix without labour was 302.7 Ohms with a deviation of 8.2. Using student's t tests it was found that there was a significant correlation (p less than 0.001) in four measurements between the impedance measure and measures obtained by extrapolating the degrees of dilatation calculated from vaginal examination. This is a preliminary study in which we have defined the conditions that are necessary to confirm these first results and to further develop the method. PMID:1401774

  7. Solid state parameters, structure elucidation, High Resolution X-Ray Diffraction (HRXRD), phase matching, thermal and impedance analysis on L-Proline trichloroacetate (L-PTCA) NLO single crystals.

    Science.gov (United States)

    Kalaiselvi, P; Raj, S Alfred Cecil; Jagannathan, K; Vijayan, N; Bhagavannarayana, G; Kalainathan, S

    2014-11-11

    Nonlinear optical single crystal of L-Proline trichloroacetate (L-PTCA) was successfully grown by Slow Evaporation Solution Technique (SEST). The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm the structure. From the single crystal XRD data, solid state parameters were determined for the grown crystal. The crystalline perfection has been evaluated using high resolution X-ray diffractometer. The frequencies of various functional groups were identified from FTIR spectral analysis. The percentage of transmittance was obtained from UV Visible spectral analysis. TGA-DSC measurements indicate the thermal stability of the crystal. The dielectric constant, dielectric loss and ac conductivity were measured by the impedance analyzer. The DC conductivity was calculated by the cole-cole plot method.

  8. Electrical impedance characterization of normal and cancerous human hepatic tissue

    International Nuclear Information System (INIS)

    The four-electrode method was used to measure the ex vivo complex electrical impedance of tissues from 14 hepatic tumors and the surrounding normal liver from six patients. Measurements were done in the frequency range 1–400 kHz. It was found that the conductivity of the tumor tissue was much higher than that of the normal liver tissue in this frequency range (from 0.14 ± 0.06 S m−1 versus 0.03 ± 0.01 S m−1 at 1 kHz to 0.25 ± 0.06 S m−1 versus 0.15 ± 0.03 S m−1 at 400 kHz). The Cole–Cole models were estimated from the experimental data and the four parameters (ρ0, ρ∞, α, fc) were obtained using a least-squares fit algorithm. The Cole–Cole parameters for the cancerous and normal liver are 9 ± 4 Ω m−1, 2.2 ± 0.7 Ω m−1, 0.5 ± 0.2, 140 ± 103 kHz and 50 ± 28 Ω m−1, 3.2 ± 0.6 Ω m−1, 0.64 ± 0.04, 10 ± 7 kHz, respectively. These data can contribute to developing bioelectric applications for tissue diagnostics and in tissue treatment planning with electrical fields such as radiofrequency tissue ablation, electrochemotherapy and gene therapy with reversible electroporation, nanoscale pulsing and irreversible electroporation

  9. Transverse Impedance of LHC Collimators

    CERN Document Server

    Métral, E; Assmann, Ralph Wolfgang; Boccardi, A; Bracco, C; Bohl, T; Caspers, Friedhelm; Gasior, M; Jones, O R; Kasinski, K; Kroyer, T; Redaelli, S; Robert-Demolaize, R; Roncarolo, F; Rumolo, G; Salvant, B; Steinhagen, R; Weiler, T; Zimmermann, F

    2007-01-01

    The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams in case of failures, and which will be moved very close to the beam, with full gaps of few millimetres, in order to protect surrounding super-conducting equipments. We present an estimate of the transverse resistive-wall impedance of the LHC collimators, the total impedance in the LHC at injection and top energy, the induced coupled-bunch growth rates and tune shifts, and finally the result of the comparison of the theoretical predictions with measurements performed in 2004 and 2006 on a prototype collimator installed in the SPS.

  10. Definition of the characteristic impedance

    Institute of Scientific and Technical Information of China (English)

    徐云生; Abbas Sayed OMAR

    1996-01-01

    Currently available definitions of the characteristic impedance are ambiguous andior inaccurate.A general definition,based on the description of discontinuities between adjacent waveguides,is given.This definition is accurate and independent of the structure concerned.So it can be applied to the design of passive components in any type of transmission lines.Using this definition,a given structure can be uniquely characterized,but the absolute value of the characteristic impedance has no sense any more.As an example,the design of a microstrip impedance transformer using this new definition is presented.Numerical results using the mode-matching method prove the accuracy of the theory.

  11. Hybrid-Source Impedance Networks

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang;

    2010-01-01

    Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...... for current-type inverters. These impedance networks can in principle be combined into two generic network entities, before multiple of them can further be connected together by applying any of the two proposed generalized cascading concepts. The resulting two-level and three-level inverters implemented using...... the cascaded networks would have a higher output voltage gain and other unique advantages that currently have not been investigated yet. It is anticipated that these advantages would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually...

  12. Impedances of Laminated Vacuum Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; Lebedev, V.; /Fermilab

    2011-06-22

    First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].

  13. Impedance analysis for dye-sensitized solar cells based on TiO2 electrode coated with Cr2O3

    Science.gov (United States)

    Li, Y.; Zhuang, Q. C.; Wang, H. T.; Xu, X. Q.; Qiang, Y. H.; Fang, L.

    2013-09-01

    TiO2 nanomaterial with typical anatase was prepared by hydrothermal method. A surface modification method was carried out by dip TiO2 electrode into Cr(NO3)3 solution. The TiO2/Cr2O3 thin film was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The current-voltage (I-V) curve revealed that short circuit current and photoelectric transfer efficiency of the modified electrode enhanced by 19.3% and 21%, respectively. The main features of electrochemical impedance spectroscopy (EIS) were discussed in a wide range of potential applied. The parameters of electron transport resistance in TiO2 film (Rw), the overall charge transfer resistance (Rct) and capacitance (Cfilm) of film were analyzed using an equivalent circuit. It was found that Rw, Rct and Cfilm switch to exponential behavior at high bias.

  14. Low profile conformal antenna arrays on high impedance substrate

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan

    2016-01-01

    This book presents electromagnetic (EM) design and analysis of dipole antenna array over high impedance substrate (HIS). HIS is a preferred substrate for low-profile antenna design, owing to its unique boundary conditions. Such substrates permit radiating elements to be printed on them without any disturbance in the radiation characteristics. Moreover HIS provides improved impedance matching, enhanced bandwidth, and increased broadside directivity owing to total reflection from the reactive surface and high input impedance. This book considers different configurations of HIS for array design on planar and non-planar high-impedance surfaces. Results are presented for cylindrical dipole, printed dipole, and folded dipole over single- and double-layered square-patch-based HIS and dogbone-based HIS. The performance of antenna arrays is analyzed in terms of performance parameters such as return loss and radiation pattern. The design presented shows acceptable return loss and mainlobe gain of radiation pattern. Thi...

  15. EXPERIMENTAL RESEARCH ON EVALUATING STRUCTURE DAMAGE WITH PIEZOELECTRIC DYNAMIC IMPEDANCE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A dynamic impedance-based structural health monitoring technique is introduced. According to the direct and the converse piezoelectric property of piezoelectric materials, the piezoceramic ( PZT ) can be used as an actuator and a sensor synchronously. If damages like cracks, holes, debonding or loose connections are presented in the structure, the physical variations of the structure will cause the mechanical impedance modified. On the basis of introducing the principle and the theory, the experiment and the analysis on some damages of the structure are studied by means of the dynamic impedance technique. On the view of experiment, kinds of structural damages are evaluated by the information of dynamic impedance in order to validate the feasibility of the method.

  16. Biohydrogen, biomethane and bioelectricity as crucial components of biorefinery of organic wastes: a review.

    Science.gov (United States)

    Poggi-Varaldo, Héctor M; Munoz-Paez, Karla M; Escamilla-Alvarado, Carlos; Robledo-Narváez, Paula N; Ponce-Noyola, M Teresa; Calva-Calva, Graciano; Ríos-Leal, Elvira; Galíndez-Mayer, Juvencio; Estrada-Vázquez, Carlos; Ortega-Clemente, Alfredo; Rinderknecht-Seijas, Noemí F

    2014-05-01

    Biohydrogen is a sustainable form of energy as it can be produced from organic waste through fermentation processes involving dark fermentation and photofermentation. Very often biohydrogen is included as a part of biorefinery approaches, which reclaim organic wastes that are abundant sources of renewable and low cost substrate that can be efficiently fermented by microorganisms. The aim of this work was to critically assess selected bioenergy alternatives from organic solid waste, such as biohydrogen and bioelectricity, to evaluate their relative advantages and disadvantages in the context of biorefineries, and finally to indicate the trends for future research and development. Biorefining is the sustainable processing of biomass into a spectrum of marketable products, which means: energy, materials, chemicals, food and feed. Dark fermentation of organic wastes could be the beach-head of complete biorefineries that generate biohydrogen as a first step and could significantly influence the future of solid waste management. Series systems show a better efficiency than one-stage process regarding substrate conversion to hydrogen and bioenergy. The dark fermentation also produces fermented by-products (fatty acids and solvents), so there is an opportunity for further combining with other processes that yield more bioenergy. Photoheterotrophic fermentation is one of them: photosynthetic heterotrophs, such as non-sulfur purple bacteria, can thrive on the simple organic substances produced in dark fermentation and light, to give more H2. Effluents from photoheterotrophic fermentation and digestates can be processed in microbial fuel cells for bioelectricity production and methanogenic digestion for methane generation, thus integrating a diverse block of bioenergies. Several digestates from bioenergies could be used for bioproducts generation, such as cellulolytic enzymes and saccharification processes, leading to ethanol fermentation (another bioenergy), thus completing

  17. Biohydrogen, biomethane and bioelectricity as crucial components of biorefinery of organic wastes: a review.

    Science.gov (United States)

    Poggi-Varaldo, Héctor M; Munoz-Paez, Karla M; Escamilla-Alvarado, Carlos; Robledo-Narváez, Paula N; Ponce-Noyola, M Teresa; Calva-Calva, Graciano; Ríos-Leal, Elvira; Galíndez-Mayer, Juvencio; Estrada-Vázquez, Carlos; Ortega-Clemente, Alfredo; Rinderknecht-Seijas, Noemí F

    2014-05-01

    Biohydrogen is a sustainable form of energy as it can be produced from organic waste through fermentation processes involving dark fermentation and photofermentation. Very often biohydrogen is included as a part of biorefinery approaches, which reclaim organic wastes that are abundant sources of renewable and low cost substrate that can be efficiently fermented by microorganisms. The aim of this work was to critically assess selected bioenergy alternatives from organic solid waste, such as biohydrogen and bioelectricity, to evaluate their relative advantages and disadvantages in the context of biorefineries, and finally to indicate the trends for future research and development. Biorefining is the sustainable processing of biomass into a spectrum of marketable products, which means: energy, materials, chemicals, food and feed. Dark fermentation of organic wastes could be the beach-head of complete biorefineries that generate biohydrogen as a first step and could significantly influence the future of solid waste management. Series systems show a better efficiency than one-stage process regarding substrate conversion to hydrogen and bioenergy. The dark fermentation also produces fermented by-products (fatty acids and solvents), so there is an opportunity for further combining with other processes that yield more bioenergy. Photoheterotrophic fermentation is one of them: photosynthetic heterotrophs, such as non-sulfur purple bacteria, can thrive on the simple organic substances produced in dark fermentation and light, to give more H2. Effluents from photoheterotrophic fermentation and digestates can be processed in microbial fuel cells for bioelectricity production and methanogenic digestion for methane generation, thus integrating a diverse block of bioenergies. Several digestates from bioenergies could be used for bioproducts generation, such as cellulolytic enzymes and saccharification processes, leading to ethanol fermentation (another bioenergy), thus completing

  18. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...... kinds of problems at different locations in the grid. This means that the best measurement methodology changes depending on the location in the grid. Three typical examples with different measurement problems at 400 kV, 132 kV and 400 V voltage level are discussed....

  19. Y-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede;

    2014-01-01

    This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched...... by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment...

  20. Input impedance characteristics of microstrip structures

    Directory of Open Access Journals (Sweden)

    A. I. Nazarko

    2015-06-01

    Full Text Available Introduction. Electromagnetic crystals (EC and EC-inhomogeneities are one of the main directions of microstrip devices development. In the article the input impedance characteristics of EC- and traditional microstrip inhomogeneities and filter based on EC-inhomogeneities are investigated. Transmission coefficient characteristics. Transmission coefficient characteristics of low impedance EC- and traditional inhomogeneities are considered. Characteristics are calculated in the software package Microwave Studio. It is shown that the efficiency of EC-inhomogeneity is much higher. Input impedance characteristics of low impedance inhomogeneities. Dependences of input impedance active and reactive parts of EC- and traditional inhomogeneities are given. Dependences of the active part illustrate significant low impedance transformation of nominal impedance. The conditions of impedance matching of structure and input medium are set. Input impedance characteristics of high impedance inhomogeneities. Input impedance characteristics of high impedance EC- and traditional inhomogeneities are considered. It was shown that the band of transformation by high impedance inhomogeneities is much narrower than one by low impedance inhomogeneities. Characteristics of the reflection coefficient of inhomogeneities are presented. Input impedance characteristics of narrowband filter. The structure of narrowband filter based on the scheme of Fabry-Perot resonator is presented. The structure of the filter is fulfilled by high impedance EC-inhomogeneities as a reflectors. Experimental and theoretical amplitude-frequency characteristics of the filter are presented. Input impedance characteristics of the filter are shown. Conclusions. Input impedance characteristics of the structure allow to analyse its wave properties, especially resonant. EC-inhomogeneity compared with traditional microstrip provide substantially more significant transformation of the the input impedance.

  1. Electrical Stimulation: A Panacea for Disease?: DARPA Investigates New Bioelectrical Interfaces for a Range of Disorders.

    Science.gov (United States)

    Grifantini, Kristina

    2016-01-01

    It seems simple: send a small electrical current to a major nerve in the body and stimulate hormones and organs to react in the way you want. New efforts by research teams are doing just that, zapping peripheral nerves attached to major organs in the hopes of addressing problems as diverse as inflammatory bowel disease, chronic pain, and posttraumatic stress disorder. Thanks to the continued advance of smaller and more efficient electronics, researchers are finding new ways to develop implantable bioelectrical devices to treat a wide range of ailments. PMID:27414632

  2. Electrical Stimulation: A Panacea for Disease?: DARPA Investigates New Bioelectrical Interfaces for a Range of Disorders.

    Science.gov (United States)

    Grifantini, Kristina

    2016-01-01

    It seems simple: send a small electrical current to a major nerve in the body and stimulate hormones and organs to react in the way you want. New efforts by research teams are doing just that, zapping peripheral nerves attached to major organs in the hopes of addressing problems as diverse as inflammatory bowel disease, chronic pain, and posttraumatic stress disorder. Thanks to the continued advance of smaller and more efficient electronics, researchers are finding new ways to develop implantable bioelectrical devices to treat a wide range of ailments.

  3. Analysis of the hydridation dynamics of metals by gaseous impedance spectroscopy. Application to electrolytic hydrogen storage; Analyse de la dynamique d'hydruration des metaux par spectroscopie d'impedance gazeuse. Application au stockage de l'hydrogene electrolytique

    Energy Technology Data Exchange (ETDEWEB)

    Millet, P. [Paris-11 Univ., Institut de Chimie Moleculaire et des Materiaux, UMR CNRS 8182, 91 - Orsay (France); Guymont, M.; Korobtsev, S. [Institut of Russian Research Center, Hydrogen Energy and Plasma Technology, Kurchatov Institute, Moscow (Russian Federation)

    2007-07-01

    In this work, the hydridation dynamics in presence of impurities is analyzed by pneumato-chemical impedance spectroscopy. The measurements are carried out with a Sieverts volumetric frame. The obtention conditions of the experimental impedances are discussed in relation with the thermodynamic states of the metal-H studied systems. A software of specific modelling has been developed: with this software, it is possible to calculate the experimental impedances and, from model equations, to accede to the microscopic kinetic parameters bound to the hydridation reactions. The results obtained on different materials, in presence of oxygen, are presented and analyzed. (O.M.)

  4. The Aberdeen Impedance Imaging System.

    Science.gov (United States)

    Kulkarni, V; Hutchison, J M; Mallard, J R

    1989-01-01

    The Aberdeen Impedance Imaging System is designed to reconstruct 2 dimensional images of the average distribution of the amplitude and phase of the complex impedance within a 3 dimensional region. The system uses the four electrode technique in a 16 electrode split-array. The system hardware consists of task-orientated electronic modules for: driving a constant current, multiplexing the current drive, demultiplexing peripheral voltages, differential amplification, phase sensitive detection and low-pass filtration, digitisation with a 14 bit analog to digital converter (ADC), and -control logic for the ADC and multiplexors. A BBC microprocessor (Master series), initiates a controlled sequence for the collection of a number of data sets which are averaged and stored on disk. Image reconstruction is by a process of convolution-backprojection similar to the fan-beam reconstruction of computerised tomography and is also known as Equipotential Backprojection. In imaging impedance changes associated with fracture healing the changes may be large enough to allow retrieval of both the amplitude and phase of the complex impedance. Sequential imaging of these changes would necessitate monitoring electronic and electrode drift by imaging an equivalent region of the contralateral limb. Differential images could be retrieved when the image of the normal limb is the image template. Better characterisation of tissues would necessitate a cleaner retrieval of the quadrature signal. PMID:2742979

  5. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    from driver to driver. Therefore, a loudspeaker emulator capable of adjusting its impedance to that of a given driver is desired for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible...

  6. Characterization of electro-acoustics impedance and its application to active noise control

    Institute of Scientific and Technical Information of China (English)

    HOU Hong; YANG Jianhua

    2004-01-01

    Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed.Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.

  7. Damage detection technique by measuring laser-based mechanical impedance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeonseok; Sohn, Hoon [Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (Daehak-ro 291, Yuseong-gu, Daejeon 305-701) (Korea, Republic of)

    2014-02-18

    This study proposes a method for measurement of mechanical impedance using noncontact laser ultrasound. The measurement of mechanical impedance has been of great interest in nondestructive testing (NDT) or structural health monitoring (SHM) since mechanical impedance is sensitive even to small-sized structural defects. Conventional impedance measurements, however, have been based on electromechanical impedance (EMI) using contact-type piezoelectric transducers, which show deteriorated performances induced by the effects of a) Curie temperature limitations, b) electromagnetic interference (EMI), c) bonding layers and etc. This study aims to tackle the limitations of conventional EMI measurement by utilizing laser-based mechanical impedance (LMI) measurement. The LMI response, which is equivalent to a steady-state ultrasound response, is generated by shooting the pulse laser beam to the target structure, and is acquired by measuring the out-of-plane velocity using a laser vibrometer. The formation of the LMI response is observed through the thermo-mechanical finite element analysis. The feasibility of applying the LMI technique for damage detection is experimentally verified using a pipe specimen under high temperature environment.

  8. A model explaining synchronization of neuron bioelectric frequency under weak alternating low frequency magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Moral, A. del, E-mail: delmoral@unizar.es [Laboratorio de Magnetismo, Departamento de Física de Materia Condensada and Instituto de Ciencia de Materiales, Universidad de Zaragoza and Consejo Superior de Investigaciones Científicas, 50009 Zaragoza (Spain); Laboratorio de Magnetobiología, Departamento de Anatomía e Histología, Facultad de Medicina, Universidad de Zaragoza, 50009 Zaragoza (Spain); Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid (Spain); Azanza, María J., E-mail: mjazanza@unizar.es [Laboratorio de Magnetobiología, Departamento de Anatomía e Histología, Facultad de Medicina, Universidad de Zaragoza, 50009 Zaragoza (Spain); Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Madrid (Spain)

    2015-03-01

    A biomagnetic-electrical model is presented that explains rather well the experimentally observed synchronization of the bioelectric potential firing rate (“frequency”), f, of single unit neurons of Helix aspersa mollusc under the application of extremely low frequency (ELF) weak alternating (AC) magnetic fields (MF). The proposed model incorporates to our widely experimentally tested model of superdiamagnetism (SD) and Ca{sup 2+} Coulomb explosion (CE) from lipid (LP) bilayer membrane (SD–CE model), the electrical quadrupolar long range interaction between the bilayer LP membranes of synchronized neuron pairs, not considered before. The quadrupolar interaction is capable of explaining well the observed synchronization. Actual extension of our SD–CE-model shows that the neuron firing frequency field, B, dependence becomes not modified, but the bioelectric frequency is decreased and its spontaneous temperature, T, dependence is modified. A comparison of the model with synchronization experimental results of pair of neurons under weak (B{sub 0}≅0.2–15 mT) AC-MF of frequency f{sub M}=50 Hz is reported. From the deduced size of synchronized LP clusters under B, is suggested the formation of small neuron networks via the membrane lipid correlation. - Highlights: • Neuron pair synchronization under low frequency alternating (AC) magnetic field (MF). • Superdiamagnetism and Ca{sup 2+} Coulomb explosion for AC MF effect in synchronized frequency. • Membrane lipid electrical quadrupolar pair interaction as synchronization mechamism. • Good agreement of model with electrophysiological experiments on mollusc Helix neurons.

  9. [Effect of dosed diet restriction on physiological remodeling and bioelectric properties of bone].

    Science.gov (United States)

    Levashov, M I; Ianko, R V; Chaka, E G; Safonov, S L

    2014-07-01

    The effect of dosed diet restriction on the physiological remodeling and bioelectric properties of bone tissue was studied in 48 male Wistar rats 3- and 18-months of age. The rate of bone tissue apposition was studied by the dynamic histomorphometry method (intravital tetracycline labeling). Electric potentials on the periosteal surface of the freshly isolated femurs were recorded. The magnitude of dielectric loss factor was determined to assess the quality of bone tissue. The control rats received a standard diet. The experimental rats received a limited diet (60 % of the standard mass) for 28 days. The magnitude and rate of the bone tissue apposition on the endosteal and periosteal surface of the tibia were less by 38.4% and 122.7% respectively in experimental rats after dosed diet restriction. Electric potential in the metaphyseal-epiphyseal growth zones of the femur was 29.7% lower, and the dielectric loss factor increased by 15.8%. The bone tissue apposition rate and the electric potential magnitude were increased 10 days after completion of the dosed diet restriction. The magnitude of the dielectric loss factor decreased after returning to the standard diet. Key words: dosed diet restriction, bone, remodelling, bioelectric properties. PMID:25669112

  10. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

    Science.gov (United States)

    Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level. PMID:26841954

  11. A novel human-machine interface based on recognition of multi-channel facial bioelectric signals

    International Nuclear Information System (INIS)

    Full text: This paper presents a novel human-machine interface for disabled people to interact with assistive systems for a better quality of life. It is based on multichannel forehead bioelectric signals acquired by placing three pairs of electrodes (physical channels) on the Fron-tails and Temporalis facial muscles. The acquired signals are passes through a parallel filter bank to explore three different sub-bands related to facial electromyogram, electrooculogram and electroencephalogram. The root mean features of the bioelectric signals analyzed within non-overlapping 256 ms windows were extracted. The subtractive fuzzy c-means clustering method (SFCM) was applied to segment the feature space and generate initial fuzzy based Takagi-Sugeno rules. Then, an adaptive neuro-fuzzy inference system is exploited to tune up the premises and consequence parameters of the extracted SFCMs. rules. The average classifier discriminating ratio for eight different facial gestures (smiling, frowning, pulling up left/right lips corner, eye movement to left/right/up/down is between 93.04% and 96.99% according to different combinations and fusions of logical features. Experimental results show that the proposed interface has a high degree of accuracy and robustness for discrimination of 8 fundamental facial gestures. Some potential and further capabilities of our approach in human-machine interfaces are also discussed. (author)

  12. Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics.

    Science.gov (United States)

    Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

    2016-01-01

    Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level. PMID:26841954

  13. Cytotoxicity evaluation of nanoclays in human epithelial cell line A549 using high content screening and real-time impedance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Navin K. [Trinity College Dublin, Department of Clinical Medicine, Institute of Molecular Medicine (Ireland); Moore, Edward; Blau, Werner [Trinity College Dublin, School of Physics (Ireland); Volkov, Yuri [Trinity College Dublin, Department of Clinical Medicine, Institute of Molecular Medicine (Ireland); Ramesh Babu, P., E-mail: babup@tcd.ie [Trinity College Dublin, Centre for Research on Adaptive Nanostructures and Nanodevices (Ireland)

    2012-09-15

    Continuously expanding use of products containing nanoclays for wide range of applications have raised public concerns about health and safety. Although the products containing nanoclays may not be toxic, it is possible that nanomaterials may come in contact with humans during handling, manufacture, or disposal, and cause adverse health impact. This necessitates biocompatibility evaluation of the commonly used nanoclays. Here, we investigated the cytotoxic effects of platelet (Bentone MA, ME-100, Cloisite Na{sup +}, Nanomer PGV, and Delite LVF) and tubular (Halloysite, and Halloysite MP1) type nanoclays on cultured human lung epithelial cells A549. For the first time with this aim, we employed a cell-based automated high content screening in combination with real-time impedance sensing. We demonstrate varying degree of dose- and time-dependent cytotoxic effects of both nanoclay types. Overall, platelet structured nanoclays were more cytotoxic than tubular type. A low but significant level of cytotoxicity was observed at 25 {mu}g/mL of the platelet-type nanoclays. A549 cells exposed to high concentration (250 {mu}g/mL) of tubular structured nanoclays showed inhibited cell growth. Confocal microscopy indicated intracellular accumulation of nanoclays with perinuclear localization. Results indicate a potential hazard of nanoclay-containing products at significantly higher concentrations, which warrant their further biohazard assessment on the actual exposure in humans.

  14. Cytotoxicity evaluation of nanoclays in human epithelial cell line A549 using high content screening and real-time impedance analysis

    International Nuclear Information System (INIS)

    Continuously expanding use of products containing nanoclays for wide range of applications have raised public concerns about health and safety. Although the products containing nanoclays may not be toxic, it is possible that nanomaterials may come in contact with humans during handling, manufacture, or disposal, and cause adverse health impact. This necessitates biocompatibility evaluation of the commonly used nanoclays. Here, we investigated the cytotoxic effects of platelet (Bentone MA, ME-100, Cloisite Na+, Nanomer PGV, and Delite LVF) and tubular (Halloysite, and Halloysite MP1) type nanoclays on cultured human lung epithelial cells A549. For the first time with this aim, we employed a cell-based automated high content screening in combination with real-time impedance sensing. We demonstrate varying degree of dose- and time-dependent cytotoxic effects of both nanoclay types. Overall, platelet structured nanoclays were more cytotoxic than tubular type. A low but significant level of cytotoxicity was observed at 25 μg/mL of the platelet-type nanoclays. A549 cells exposed to high concentration (250 μg/mL) of tubular structured nanoclays showed inhibited cell growth. Confocal microscopy indicated intracellular accumulation of nanoclays with perinuclear localization. Results indicate a potential hazard of nanoclay-containing products at significantly higher concentrations, which warrant their further biohazard assessment on the actual exposure in humans.

  15. Oblique impacts into low impedance layers

    Science.gov (United States)

    Stickle, A. M.; Schultz, P. H.

    2009-12-01

    Planetary impacts occur indiscriminately, in all locations and materials. Varied geologic settings can have significant effects on the impact process, including the coupling between the projectile and target, the final damage patterns and modes of deformation that occur. For example, marine impact craters are not identical to impacts directly into bedrock or into sedimentary materials, though many of the same fundamental processes occur. It is therefore important, especially when considering terrestrial impacts, to understand how a low impedance sedimentary layer over bedrock affects the deformation process during and after a hypervelocity impact. As a first step, detailed comparisons between impacts and hydrocode models were performed. Experiments performed at the NASA Ames Vertical Gun Range of oblique impacts into polymethylmethacrylate (PMMA) targets with low impedance layers were performed and compared to experiments of targets without low impedance layers, as well as to hydrocode models under identical conditions. Impact velocities ranged from 5 km/s to 5.6 km/s, with trajectories from 30 degrees to 90 degrees above the horizontal. High-speed imaging provided documentation of the sequence and location of failure due to impact, which was compared to theoretical models. Plasticine and ice were used to construct the low impedance layers. The combination of experiments and models reveals the modes of failure due to a hypervelocity impact. How such failure is manifested at large scales can present a challenge for hydrocodes. CTH models tend to overestimate the amount of damage occurring within the targets and have difficulties perfectly reproducing morphologies; nevertheless, they provide significant and useful information about the failure modes and style within the material. CTH models corresponding to the experiments allow interpretation of the underlying processes involved as well as provide a benchmark for the experimental analysis. The transparency of PMMA

  16. Beam Coupling Impedances of Small Discontinuities

    CERN Document Server

    Kurennoy, S S

    2000-01-01

    A general derivation of the beam coupling impedances produced by small discontinuities on the wall of the vacuum chamber of an accelerator is reviewed. A collection of analytical formulas for the impedances of small obstacles is presented.

  17. 一种换能器阻抗测试分析及数据管理系统的设计与实现%Design and Implementation of Transducer Impedance Test-Analysis and Data- Manage System

    Institute of Scientific and Technical Information of China (English)

    张静; 杨惠珍; 郝莉莉; 李家宽

    2012-01-01

    A new impedance test and analytical system for transducer is designed and implemented. The test and analysis software running in the host computer is developed based on Labwindows/CVI platform. The host computer communicates with a precision impedance analyzer- Agilent4294A by GFIB. It can not only display the measurement data and graph synchronously with Agilent4294A, but also save data to database. Through the data manage software- users can consult- analysis, or display the lest data saved in the database and draw performance curves for these data. The application results show that the measurement data are accurate, the performance of the system is stable, and the operation is convenient.%设计并实现了一种换能器阻抗测试分析及数据管理系统;基于LabWIndows/CVI开发的换能器阻抗测试软件运行在PC机上,通过GPIB通信接口控制Agilent4294A高精度阻抗分析仪对换能器进行阻抗参数测试,并在PC机上实时显示测试数据和测试曲线,同时将测试结果保存到数据库中;数据管理软件实现了对全部测试数据的查询、分析、显示和报告生成等功能;应用表明该系统测量精度高、性能稳定、操作简便,提高了测试效率,实现了数据与文档的电子化,具有很好的应用和推广价值.

  18. Impact of acute changes of left ventricular contractility on the transvalvular impedance: validation study by pressure-volume loop analysis in healthy pigs.

    Directory of Open Access Journals (Sweden)

    Vincenzo Lionetti

    Full Text Available BACKGROUND: The real-time and continuous assessment of left ventricular (LV myocardial contractility through an implanted device is a clinically relevant goal. Transvalvular impedance (TVI is an impedentiometric signal detected in the right cardiac chambers that changes during stroke volume fluctuations in patients. However, the relationship between TVI signals and LV contractility has not been proven. We investigated whether TVI signals predict changes of LV inotropic state during clinically relevant loading and inotropic conditions in swine normal heart. METHODS: The assessment of RVTVI signals was performed in anesthetized adult healthy anesthetized pigs (n = 6 instrumented for measurement of aortic and LV pressure, dP/dtmax and LV volumes. Myocardial contractility was assessed with the slope (Ees of the LV end systolic pressure-volume relationship. Effective arterial elastance (Ea and stroke work (SW were determined from the LV pressure-volume loops. Pigs were studied at rest (baseline, after transient mechanical preload reduction and afterload increase, after 10-min of low dose dobutamine infusion (LDDS, 10 ug/kg/min, i.v, and esmolol administration (ESMO, bolus of 500 µg and continuous infusion of 100 µg·kg-1·min-1. RESULTS: We detected a significant relationship between ESTVI and dP/dtmax during LDDS and ESMO administration. In addition, the fluctuations of ESTVI were significantly related to changes of the Ees during afterload increase, LDDS and ESMO infusion. CONCLUSIONS: ESTVI signal detected in right cardiac chamber is significantly affected by acute changes in cardiac mechanical activity and is able to predict acute changes of LV inotropic state in normal heart.

  19. Reducing the SPS Machine Impedance

    CERN Document Server

    Collier, Paul; Guinand, R; Jiménez, J M; Rizzo, A; Spinks, Alan; Weiss, K

    2002-01-01

    The SPS as LHC Injector project has been working for some time to prepare the SPS for its role as final injector for the LHC. This included major work related to injection, acceleration, extraction and beam instrumentation for the LHC beams [1]. Measurements carried out with the high brightness LHC beam showed that a major improvement of the machine impedance would also be necessary [2]. In addition to removing all lepton related components (once LEP operation ended in 2000), the decision was made to shield the vacuum system pumping port cavities. These accidental cavities had been identified as having characteristic frequencies in the 1-1.5GHz range. Since the SPS vacuum system contains roughly 1000 of these cavities, they constitute a major fraction of the machine impedance. As removal of the ports and associated bellows is not possible, transition shields (PPS) had to be designed to insert within the pumping port cavities.

  20. A spatial impedance controller for robotic manipulation

    NARCIS (Netherlands)

    Fasse, Ernest D.; Broenink, Jan F.

    1997-01-01

    Mechanical impedance is the dynamic generalization of stiffness, and determines interactive behavior by definition. Although the argument for explicitly controlling impedance is strong, impedance control has had only a modest impact on robotic manipulator control practice. This is due in part to the