Bioelectrical impedance analysis-derived phase angle (PhA) has been gaining attention in the clinical evaluation of nutritional status because it is thought to be a proxy of water distribution and ...body cell mass; it is also associated to muscle strength and is an effective predictor of different clinical outcomes. Since an association may be expected between PhA and sarcopenia (defined by low skeletal muscle mass and impaired muscle function), the aim of this systematic review was to evaluate: a) changes in PhA due to sarcopenia; b) prevalence of sarcopenia according to PhA values; c) derivation of phase angle cut-offs for detecting sarcopenia; d) sarcopenia and PhA as predictors of clinical outcomes.
A systematic research on electronic databases (PubMed, Embase, Scopus and Web of Science) from inception to January 31st, 2020 was performed according to PRISMA checklist. Using PICOS strategy, “P” corresponded to participants of any age, gender or ethnicity, “I” designated diagnosis of sarcopenia, “C” indicated subjects without sarcopenia, “O” corresponded to PhA, and “S” selected all study types. Methodological quality was assessed using the National Institute of Health (NIH) quality assessment tool.
Through the initial literature search and after removing duplicates and excluding papers by screening titles and abstracts, 79 potentially relevant studies were examined. Thirteen studies (7668 subjects) met the inclusion criteria. The overall risk of bias was low. Sarcopenia was associated with a significant lower PhA in seven studies out of eight, while five studies out of six reported a high prevalence of sarcopenia was in patients with low PhA. Different cut-off point values from 4.05 to 5.05° have been derived for the identification of sarcopenia. PhA and sarcopenia were independent predictors of survival in cancer patients and geriatric hospitalized patients.
Data from the selected papers demonstrate that PhA is decreased in sarcopenic subjects and the prevalence of sarcopenia is higher in subjects with low PhA. Further studies are needed to determine to what extent PhA may be valuable in detecting low muscle quality and/or identifying sarcopenia.
•Phase angle is decreased in sarcopenic subjects.•The prevalence of sarcopenia is higher in subjects with low phase angle.•Phase angle may help in detecting low muscle quality and identifying sarcopenia.•Different cut-off phase angle values have been derived for identifying sarcopenia.
The bioimpedence phase angle has been considered as a predictor for morbidity and mortality in different clinical situations, although reference values from a large healthy population are lacking. ...The aim of this meta-analysis is to estimate mean phase-angle values in healthy individuals.
This meta-analysis systematically searched MEDLINE, EMBASE, The Cochrane Controlled Trials Register, SCIELO, LILACS, CINAHL, Web of Science and gray literature for studies estimating mean phase angles. Quality of evidence was assessed for all studies and subgroup (males and females) meta-analysis stratified by age group according to literature (up to 2; 3–5; 6–12; 13–15; 16–18; 19–28; 29–38; 39–48; 49–58; 59–69; 70–80 and >80 years of age) were conducted using random-effects models.
A total of 46 studies including 249,844 subjects were selected for the present analysis. Males show a pooled estimate of the mean phase angle of 3.6 (95% CI: 3.0–4.1) for infants (0–2 y), increasing progressively to 7.3 (95% CI: 7.0–7.5) at the teenage phase (16–18 y), stabilizing during adult ages (18–38) and decreasing progressively with ongoing years with an estimate of 5.3 (95% CI: 4.5–6.0) for elderly above 80 years old. Similarly, females start from 3.7 (95% CI: 3.2–4.3) for infants (0–2 y), increasing progressively to 6.4 (95% CI: 6.1–6.8) at the teenage phase (16–18 y), stabilizing during adult ages (18–48) and decreasing progressively with ongoing years with an estimate of 5.4 (95% CI: 5.3–5.6) for elderly above 80 years old. Also, males have higher estimates than females for all age groups except for infants (0–2) and subjects older than 80 years old. Heterogeneity was high for all age groups.
In both sexes, phase-angle values have a similar pattern that start from infants, increase progressively up to the teenage phase, stabilize during adult ages, and then decrease progressively in older subjects and the elderly.
•Phase angle is a predictor of morbidity and mortality in different clinical situations. Nevertheless, reference values from a large healthy population data are lacking.•This study synthesizes data from 46 studies including 249,844 health individuals and provides estimates for mean phase angle for males and females stratified by age.•Phase-angle increases progressively from the first years of life until 18 years of age, then stabilizes from 19 until 48 years and progressively decreases with ongoing years.•This study provides references values that can contribute to the prediction of health status in clinical practice.
To evaluate the relationship between physical activity and phase angle.
Systematic Review and Meta-analysis.
Electronic searches of MEDLINE (via PUBMED), EMBASE, Cochrane Central Register of ...Controlled Trials (CENTRAL, The Cochrane Library), SciELO, LILACS, SPORTDiscus, Scopus, and Web of Science from inception to December 10th, 2017.
The PICOS strategy was defined, in which “P” corresponded to participants of any age, sex or ethnicity, “I” indicated any type of physical activity program, “C” denoted lack of exercise or irregular physical activity, “O” corresponded to the phase angle obtained by bio-impedance, and “S” indicated longitudinal or cross-sectional studies.
In cross-sectional studies the phase angle was higher among the active individuals (MD = 0.70; 95% CI: 0.48, 0.92, P < 0.001), with low heterogeneity (I2 = 0%; P = 0.619). In longitudinal studies, the mean of the difference of phase angles from the baseline was significantly higher for the active group than the control group (MD = 0.30; 95% CI: 0.11, 0.49, P = 0.001), with low heterogeneity (I2 = 13%, P = 0.331). No evidence of publication bias was found and the overall risk of bias was moderate to high.
The positive association of physical activity with phase angle reinforces the importance of routinely including exercise in health care. We also identified the need for further studies to define with different types, intensities and frequencies of exercises should be conducted in order to find the best dose-effect relationship.
Cold extrusion 3D food printing is an emerging technology which enables the manufacture of food in different shapes and structures and offers huge potential for personalised food products. This study ...investigates rheological properties and printability (shape fidelity) of food-grade hydrocolloid pastes. From this study, it was found that if the phase angle is in the range of 3°–15° and the relaxation exponent is in the range of 0.03–0.13 the paste material is printable, which means that it can support its own-weight if printed. As the demand for inks for 3D printing increases, rheological measurements can rapidly assist with the development of new ink feedstocks.
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•3D printing of hydrocolloids is influenced by their rheological properties.•Thixotropic hydrocolloid systems were used as a model for food 3D printing.•Over 50 combinations (concentration/type) of hydrocolloids were analysed and their rheological properties were reported.•Phase angle and relaxation exponent are used to get insight on 3D printing of hydrocolloids.•This design rule can be used to identify food formulations with tailored made properties for use in food 3D printing.
It is well-known that series-series compensated resonant inductive wireless power transfer links (SS-IWPTL) may be designed to attain load independent voltage output (LIVO) for given operating ...frequency and coupling coefficient. Unfortunately, corresponding inverter output impedance is either highly-inductive or highly-capacitive (inductive region is typically preferred due to natural zero-voltage switching (ZVS) of inverter transistors), significantly increasing inverter volt-ampere (VA) rating. The letter demonstrates that designing the SS-IWPTL for operation in the capacitive region and then adding a shunt inductor across AC-side terminals of either inverter or rectifier while allows attaining inverter zero phase angle (ZPA) thus minimizing its VA rating.
In this paper, electrochemical impedance spectroscopy (EIS) method was used to investigate the degradation of four types of organic coating systems, which were brushed on three kinds of metal ...substrates and applied in various accelerated corrosion environments. Because the change of phase angle in the middle frequency region can effectively reflect the variation of the coating protection performance, with the aid of computer programs, the Pearson correlation, Cosine similarity and Euclidean distance correlation analysis methods were used to deeply analyze the impedance data of total 60 samples from different coating systems, so as to accurately determine the frequencies at which the phase angles present the best correlation with the low-frequency impedance (|Z|0.01 Hz). The results indicate that using Pearson correlation coefficient (r) to analyze the impedance data, the top eight ranked frequencies determined are in the range of 0.85 Hz to 41.75 Hz, the variations of phase angles in this range are closely related to that of the |Z|0.01Hz. Based on this, the impedance data of all the samples are furtherly analyzed using Cosine similarity and Euclidean distance methods and the obtained frequencies are 4.52 Hz or 41.75 Hz. The final goal is to establish a rapid evaluation technique based on phase angles at middle frequency range, and promote the field engineering application of electrochemical impedance spectroscopy in coating performance evaluation.
Wireless power transfer (WPT) is an emerging technology that can realize electric power transmission over certain distances without physical contact, offering significant benefits to modern ...automation systems, medical applications, consumer electronics, etc. This paper provides a comprehensive review of existing compensation topologies for the loosely coupled transformer. Compensation topologies are reviewed and evaluated based on their basic and advanced functions. Individual passive resonant networks used to achieve constant (load-independent) voltage or current output are analyzed and summarized. Popular WPT compensation topologies are given as application examples, which can be regarded as the combination of multiple blocks of resonant networks. Analyses of the input zero phase angle and soft switching are conducted as well. This paper also discusses the compensation requirements for achieving the maximum efficiency according to different WPT application areas.
This paper extends the high-frequency transformer isolation concept to the Z-source (ZS) ac-ac converters and introduces a new family of high-frequency transformer isolated (HFTI) ZS ac-ac ...converters. The proposed HFTI-ZS converters retain all the benefits of their existing nonisolated counterparts, such as providing a larger range of output voltage with buck-boost functionality, reversing or maintaining the phase angle, reducing the in-rush and harmonic currents, and improving reliability. In addition to these benefits, the high-frequency (20 kHz) transformer (HFT) in the proposed ZS ac-ac converters provides the electrical isolation and safety with high power density as it eliminates the need for bulky and heavy line frequency (50 or 60 Hz) transformer for galvanic isolation, in applications such as dynamic voltage restorers, etc. The dc-blocking capacitor added in series with the HFT results in only ac voltage applied across its windings, which avoids its saturation. Various ZS-based HFTI ac-ac converters are proposed in this paper, and to verify their operation and advantages, example of quasi-ZS (qZS)-based isolated ac-ac converter is considered in detail. The commutation strategy is also developed to achieve the safe commutation, which avoids the current and voltage spikes without using any RC snubber. A 200-W laboratory prototype of HFTI-qZS ac-ac converter is fabricated and experiments are performed to validate the advantages of the proposed ac-ac converters.
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