Phase Angle Reduction Research Articles

Skin Bioimpedance Analysis to Determine Cellular Integrity by Phase Angle in Women with Fibromyalgia: A Cross-Sectional Study.

Oxidative stress has been proposed as a significant part of the pathogenesis of fibromyalgia, and the phase angle in bioelectrical impedance analysis has been explored as a potential technique to screen oxidative abnormalities. This study recruited 35 women with fibromyalgia and 35 healthy women, who underwent bioelectrical impedance analysis and maximum isometric handgrip strength tests. Women with fibromyalgia showed lower bilateral handgrip strength (right hand: 16.39 ± 5.87 vs. 27.53 ± 4.09, p < 0.001; left hand: 16.31 ± 5.51 vs. 27.61 ± 4.14, p < 0.001), as well as higher body fat mass (27.14 ± 10.21 vs. 19.94 ± 7.25, p = 0.002), body fat percentage (37.80 ± 8.32 vs. 30.63 ± 7.77, p < 0.001), and visceral fat area (136.76 ± 55.31 vs. 91.65 ± 42.04, p < 0.01) compared with healthy women. There was no statistically significant difference in muscle mass between groups, but women with fibromyalgia showed lower phase angles in all body regions when compared with healthy control women (right arm: 4.42 ± 0.51 vs. 4.97 ± 0.48, p < 0.01; left arm: 4.23 ± 0.48 vs. 4.78 ± 0.50, p < 0.001; trunk: 5.62 ± 0.77 vs. 6.78 ± 0.84, p < 0.001; right leg: 5.28 ± 0.56 vs. 5.81 ± 0.60, p < 0.001; left leg: 5.07 ± 0.51 vs. 5.69 ± 0.58, p < 0.001; whole body: 4.81 ± 0.47 vs. 5.39 ± 0.49, p < 0.001). Moreover, whole-body phase-angle reduction was only predicted by the presence of fibromyalgia (R2 = 0.264; β = 0.639; F(1,68) = 24.411; p < 0.001). Our study revealed significantly lower phase angle values, lower handgrip strength, and higher fat levels in women with fibromyalgia compared to healthy controls, which are data of clinical relevance when dealing with such patients.

Alteration in body water compartments following intermittent fasting in Ramadan.

Concerning the health outcomes of intermittent fasting in Ramadan, loss of fat-free mass (FFM) and changes in the content of body water are of paramount importance. In this study, we aimed to assess the concomitant alterations in body water compartment and composition following Ramadan fasting in healthy individuals. We conducted an open-label cohort with longitudinal follow-up, involving 73 healthy medical staff who planned to fast for at least 20 consecutive days during Ramadan. The primary outcomes of the cohort were changes in parameters related to body composition and water content, which were measured using bioelectrical impedance analysis by InBody S10 (InBody, Seoul, South Korea). Based on the results, the participants' weight decreased significantly by approximately 1,030 g after the fasting period (p < 0.001). There was a significant reduction in the fat mass of an average 828 g (p < 0.001), which accounted for more than 80% of the weight loss. The decline in FFM was not significant (190 g; p = 0.234). The amount of total body water (TBW) and extracellular water (ECW) did not change, while intracellular water (ICW) decreased significantly by about 160 mL (p = 0.027). A strong correlation was observed between the reduction of phase angle and the increase in ECW/TBW ratio (R = -0.71, p < 0.001). Overall, our findings revealed a minimal amount of weight loss after Ramadan fasting, which was mainly due to the loss of fat mass. The parallel decrease in ICW and phase angle indicated impaired cell membrane integrity, with subsequent movement of water from the intracellular to the extracellular compartment.

Application of bioelectrical impedance analysis in monitoring patients with head and neck cancer after surgical intervention.

It is estimated that about 60% of patients with head and neck cancer (HNC) show poor nutritional status, and approximately 80% lose weight during treatment. The impact of surgical procedures on the risk of further weight loss, severe malnutrition and cachexia is a significant clinical problem that determines the higher incidence of postoperative complications, reduced effectiveness of the treatment used, longer hospitalization time, poor quality of life and higher mortality among patients. Bioelectrical impedance analysis (BIA) is currently recognized as a useful method of assessing the body composition and therefore the nutritional status of cancer patients. The aim of this study is to investigate whether measured and calculated parameters of BIA change shortly after surgery and could reflect the health of cells and body composition changes. We enrolled 54 patients (males) with advanced HNC in this observational study. We collected detailed anthropometric and BIA derived data. The Subjective Global Assessment (SGA) was used to assess the nutrition. In the assessment performed one week after the surgery, compared to the condition on the day of surgery, the patients had significantly lower values of nutritional status (weight; body mass index - BMI; SGA), body composition (free fat mass - FFM; intracellular fluid - ICF; total body water - TBW). Other changes include a significant increase in fat mass (FM) or extracellular fluid (ECF). Moreover, a significant reduction of phase angle (PA, one of the most important BIA derived prognostic factors) was also noted. Apart from the baseline assessment of the body composition and diagnosing nutritional disorders, it seems, that BIA should be considered also in the monitoring of HNC patients undergoing surgery.

A Higher Phase Angle Is Associated with Greater Metabolic Equivalents in Women 1 Year After Bariatric Surgery.

Phase angle (PhA), proposed as an indicator of the number, integrity, and function of cells and evaluated in some clinical situations, decreases after bariatric surgery (BS). In contrast, higher values are found in physically active or exercising individuals. We therefore evaluated the influence of physical activity on PhA after BS. The PhA and body composition (obtained by bioelectrical impedance analysis), physical activity level (obtained by International Physical Activity Questionnaire), and metabolic equivalents (METs) were evaluated in adult women submitted to BS. The PhA and body composition were evaluated at three time points: before and 6 and 12months after surgery. Physical activity level and METs were measured at the two postoperative time points. A reduction in PhA was observed 6 (p < 0.01) and 12months (p < 0.01) after BS, with no significant difference between time points. A moderate or high physical activity level was found in 81% of the volunteers after 6months and in 65% after 12months. METs were reduced after 12months compared to 6months. A positive correlation (p < 0.05) was observed between PhA and body cell mass after surgery. There was a significant positive correlation (p < 0.01) between PhA and METs after 12months. Physical activity may attenuate the PhA reduction that occurs after BS, with this parameter reflecting the engagement of these patients in this type of activity.

Fracture Initiation Mechanisms of Multibranched Radial-Drilling Fracturing

Abstract Compared with conventional hydraulic fracturing, radial-drilling fracturing presents remarkable advantages and can effectively develop low-permeability reservoirs. The radial borehole can reduce formation fracture pressure and guide the fracture initiation and propagation. Due to the large radial borehole azimuth or the strong anisotropy of the reservoir, the single radial borehole may not efficiently guide the fracture propagation. The researchers proposed multibranched radial-drilling fracturing. However, the research on fracture initiation of multibranched radial-drilling fracturing is inadequate. Radial boreholes usually need certain dip angles to avoid penetrating the interlayer, but the effect of dip angle on the stress field has never been considered before. In this paper, an analytical model for predicting stress distribution around the main wellbore with multiradial boreholes of arbitrary dip angle, azimuth angle, and phase angle is established for the first time, taking full account of the influences of in situ stress, internal pressure, and fracture fluid infiltration on the stress field. The model is utilized to calculate the fracture initiation pressure (FIP) and point out the specific fracture initiation location (FIL). The influences of azimuth angle, dip angle, phase angle, depth difference, and the stress profile radius on fracture initiation pressure, fracture initiation location, and maximum tensile stress distribution are investigated, and a series of sensitivity analyses are carried out. The results show that the areas between the radial boreholes and closer to the walls of radial boreholes are more prone to tensile failure, which provides a theoretical basis for radial boreholes guiding fracture initiation. The reduction of phase angle and depth difference enhances the interference between radial wells, which is conductive to the formation of hydraulic fracture networks between them. As the dip angle increases, the stress becomes increasingly concentrated, and the preferential rock tensile failure becomes increasingly easy. The farther the stress profile is from the main wellbore axis, the smaller it will be influenced by the main wellbore. When the distance exceeds 2R, the maximum tensile stress distribution on the profile remains constant. The research enriches the fracture initiation mechanism of multibranched radial-drilling fracturing and provides guidance for optimizing radial borehole layout parameters of hydraulic fracturing directed by multiradial boreholes.

Four-point bending mechanical behavior of aged asphalt mixtures containing charcoal

The asphalt coating is the layer responsible for resisting the traffic stresses of a highway. However, the search for new materials to mitigate environmental impacts and improve pavement quality is increasing. Thus, the mechanical behavior of asphalt mixtures was analyzed through the four-point bending test after the molding process and aged, with the participation of residues in the form of charcoal. The frequencies of 1Hz, 3Hz, 5Hz, 10Hz, 20Hz and 1Hz are considered at temperatures of 25°C and 40°C. The aging process contributed to improve the mechanical characteristics of the charcoal mixture at a temperature of 25 ° C, considering that there was an increase in stiffness at frequencies from 1 to 20 Hz, as well as a reduction in phase angle at frequencies of 3 Hz. , 5 Hz, 10 Hz and 20 Hz.

E-Waste plastic powder modified bitumen: rheological properties and performance study of bituminous concrete

Bitumen being a viscoelastic material sometimes needs modification for stability under adverse environmental conditions. Several researchers have carried out the modification of bitumen with unconventional materials namely; crumb rubber (CR), fibers, etc. In this study, Viscosity grade (VG) −30 bitumen has modified with e-waste plastic powder and termed as e-waste plastic powder modified bitumen (EPPMB). Noticeable improvement in rheological properties of EPPMB was observed when tested with a dynamic shear rheometer (DSR) and conventional tests. Bitumen modified with 5% e-waste plastic powder by weight of bitumen fulfills the guidelines of Indian specification, hence was selected for further study. Marshall stability of bituminous concrete (BC) prepared with EPPMB which is named as EPPMBC was found to be improved. Cyclic triaxial tests were performed to evaluate complex modulus parameters at 10, 25 and 40°C for 0.1–10 Hz frequency. Dynamic modulus was improved up to 10% at 40°C. Reduction in phase angle (δ) at 40°C may be attributed to the increase in elasticity of EPPMBC. The fatigue resistance improved by 19% at 10°C whereas rutting resistance enhanced by 28% at 40°C.

Bioimpedance phase angle is associated with serum transthyretin but not with prognostic inflammatory and nutritional index during follow-up of women submitted to bariatric surgery

Phase angle (PhA) has been used as a prognostic indicator in several clinical situations. However, the use of PhA as a prognostic tool in bariatric patients is less known. The aim of this study was to evaluate PhA as a prognostic index and its correlation with the prognostic inflammatory and nutritional index (PINI) during follow-up of women subjected to bariatric surgery. Twenty female volunteers were studied. Body weight, body mass index (BMI), PhA, and biochemical components of PINI [serum C-reactive protein, alpha-1-acid glycoprotein, albumin, and transthyretin (TTR) concentrations] were evaluated at three time points: before (T0) and approximately 2-3 (T1) and 6 (T2) months after surgery. One-way repeated measures ANOVA or the Friedman test with Tukey's post hoc test was used depending on data normality. The associations between PhA and the other parameters were evaluated using Spearman's (nonparametric data) or Pearson's (parametric data) correlation coefficient. Phase angle reduction was accompanied by a significant decrease in body weight and BMI at T1 (P<0.05), but not at T2 (P>0.05). PINI indicated low-risk complications during the preoperative period and no risk during the postoperative period (T1 and T2). No significant correlation was observed between PhA and PINI (P>0.05). Regarding its association with the biochemical components of PINI, lower PhA values were significantly correlated with lower serum TTR concentrations (r=0.633, P<0.001). Phase angle was not associated with PINI, although lower values were correlated with lower serum TTR, suggesting that PhA reduction is associated with an increased nutritional risk.

The effect of processing conditions on the rheological properties of blends of ultra high molecular weight polyethylene with high‐density polyethylene

Blends of high‐density polyethylene (HDPE) with small amounts of ultra‐high molecular weight polyethylene (UHMWPE) were prepared by melt mixing in a twin‐screw microcompounder. Two types of UHMWPE differing in their states of chain entanglement were used. The blend composition, time of mixing, and rotation speed of the screws were varied. Rheological properties of the blends were studied in oscillatory shear and uniaxial elongational tests. Reduction in phase angle measured in dynamic shear rheology and increase in extensional strain hardening were found to be useful indicators for quantifying the extent of mixing of the two components. Although the disentangled UHMWPE showed reasonable mixing with HDPE during typical residence times of melt compounding operations, the entangled UHMWPE remained essentially undissolved. The extent of mixing increased with mixing time and screw speed. POLYM. ENG. SCI., 59:821–829, 2019. © 2018 Society of Plastics Engineers

May nutritional status worsen during hospital stay? A sub-group analysis from a cross-sectional study.

Hospital malnutrition is a detrimental prognostic factor regarding hospital mortality, complications, and length of stay. However, the role of hospitalization itself on nutritional status has not been fully elucidated. We report the results of a secondary analysis from the dataset of a recent cross-sectional study at Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. Data from patients evaluated at admission and discharge were collected and compared. One hundred thirty-nine patients were evaluated. Mean length of stay was 13.6 (± 7.7) days. Patients at risk of malnutrition, according to NRS-2002, were 75 (53.9%), while 63 (45.3%) were malnourished according to ESPEN Criteria. Compared to admission, at discharge, patients reported a significant decrease in Mid-Upper Arm Circumference (MUAC)-from 26.5cm (± 3.6) to 25.9cm (± 3.7) (p = 0.016), a reduction in Phase angle (PhA)-from 4.25° (± 1.20) to 4.01° (± 1.15) (p = 0.005), fat-free mass (FFM)-from 47.5kg (± 9.19) to 44.9kg (± 9.4) (p = 0.03) and fat-free mass index (FFMI)-from 16.9kg/m2 (± 2.3) to 15.8kg/m2 (± 2.7) (p = 0.04). Laboratory data showed a reduction of albumin-from 29.2 (± 5.7) to 28.0 (± 5.9) (p = 0.01) and Onodera's PNI- from 29.1 (± 5.6) to 27.6kg (± 5.6) (p = 0.039). At the multivariate linear regression analysis, the variables significantly associated with a worsening of PhA at discharge are the PhA value at admission and the diagnosis of malnutrition according to ESPEN Criteria. Hospitalization leads to significative changes in nutritional status. A clinical concern should be raised about the quality of hospital food and meal times and on the need for a clinical nutritionist on the ward.

Investigation of Rheological Characteristics of Carbon Fiber Modified Asphalt Binder

The performance of asphalt concrete is strongly dependent on the rheological properties of asphalt binders. In this paper, PAN carbon fiber was employed to improve the conductivity of asphalt mixture. To better understand the performance of conductive asphalt mixture, the present study investigated the rheological characteristics of asphalt binders containing PAN carbon fiber. Additionally, scanning electron microscopy (SEM) was used to elucidate the microstructure and interface reaction between the asphalt and the PAN carbon fiber. Experimental results showed that carbon fibers in the asphalt can overlap each other and form a three-dimensional space structure, which could transfer and buffer the stress. Moreover, the addition of PAN carbon fiber increases the complex shear modulus of modified asphalt binders, which means higher resistance to the permanent deformation. Furthermore, the reduction of phase angle implied the increment of elastic portion in the visco-elastic of carbon modified asphalt binder.

Rheological Properties of High Grade Asphalt and its Mixture

Viscosity test, dynamic shear test, dynamic modulus test and creep test were conducted to investigate the rheological properties of high modulus asphalt and its mixture. Test results indicated that the viscosity of hard grade asphalt could be increased when compared with the ordinary asphalt, especially at high temperatures. The complex shear modulus and dynamic modulus of hard-grade asphalt binder and its mixture were increased, which implied that the stiffness of them was enhanced. Furthermore, the elastically portions for viscoelastic property of asphalt binders were increased, which resulted in the reduction of phase angle for hard grade asphalt binders and mixtures. The rutting parameter for hard-grade asphalt mixture was increased remarkably, which revealed that the resistance to permanent deformation could be significantly improved for hard grade asphalt mixture.

A new method for standing phase angle reduction in system restoration by incorporating load pickup as a control means

In restoring a power system after a major disturbance, system operators often encounter an excessive standing phase angle difference (SPA) between two buses of a circuit breaker when a transmission line is energized and results in a loop closure. Under such a condition, there is high risk of damage to nearby generators and other equipments for the breaker/loop closure operation. Since the SPA value is a function of the restoring system topology, load and generation injections, the SPA reduction becomes an important problem in system restoration. Presently, generation rescheduling is adopted as a primary control means and load shedding is used as the final resort to reduce the SPA. In fact, there remains a lot of unserved load in the system throughout the restoration process. Since the unserved load that can help reduce the SPA is not picked up and selected as a control means, the existing control strategy for SPA reduction is not optimal for a system under restorative state. In this paper, a new method that incorporates load pickup as a control means is proposed to address the SPA reduction problem. Firstly, a general principle for SPA reduction is established, i.e., a smaller SPA can be achieved by lowering the total active power flow transmitted from the sending-end to the receiving-end subsystem. Based on which, the pickup of load in the sending-end subsystem and the increased active power generation in the receiving-end subsystem are combined as control means. Then a mixed integer nonlinear programming (MINLP) algorithm and an alternative two-stage decoupled (TSD) algorithm are proposed to develop specific control strategies. The algorithms can help restore some unserved load during the process of SPA reduction and, thus, are more effective in achieving the goal of power system restoration. Simulation results on the New England test system demonstrate the effectiveness of the proposed algorithms.

Asphalt binders modified by SBS and SBS/nanoclays: effect on rheological properties

In this work, it was investigated the effect of organically modified vermiculite and montmorillonite (OVMT and OMMT, respectively) in asphalt binders (AB) modified by SBS (styrene-butadiene-styrene). The physical and rheological properties were performed for AB, 4.0% SBS MB and nanocomposite AB modified by 2.5% SBS with 2.5% of organoclays. The modified binders (MB) result in the enhancement of complex modulus (G*) and reduction of phase angle (d), which means greater resistance to permanent deformation. The viscosity, penetration and thermal susceptibility were appropriate. The black diagrams show that the effect of nanoclays OVMT and OMMT was similar to the effect of Cloisite®. The rheological properties of the nanocomposite were comparable to the 4.0% SBS MB, identifying a cost reduction due to the potential of replacing polymer with clay. The presence of OVMT improved the storage stability of SBS MB, an important result, as the phase separation is a major obstacle to the use of SBS in paving.

Standing Phase Angle Reduction Based on a Wide Area Monitoring System Using Genetic Algorithm

During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. A novel approach for reducing large standing phase angle (SPA) based on Genetic Algorithm (GA) is presented in this paper. The proposed approach starts with a state estimation on Wide Area Monitoring System (WAMS) data measurements and considering power system operation and angular stability constraints, seeks an optimal control action scenario for reducing SPA. Since these constraints are evaluated based on WAMS data, the presented approach is considerably high speed and accurate. As an optimization problem, objective function of the proposed approach is to minimize variation from the current state of the power system. Simulation results on the IEEE 118 bus test system clearly show efficiency of the approach.

Bioelectrical impedance analysis in clinical practice: implications for hepatitis C therapy

Aims: Phase angle (PA), determined by bioelectrical impedance analysis (BIA), detects changes in tissue electrical properties and has been found to have a prognostic value in various chronic diseases such as liver cirrhosis. The aim of this prospective study was to investigate the clinical and the prognostic value of BIA-derived PA and also alterations in the body composition in patients with chronic hepatitis C infection under antiviral therapy. Patients and Methods: We evaluated 37 HCV infected patients. Overall, 22 HCV patients with genotype 3 treated for 24 weeks and also 15 patients with genotype 1 treated for 48 weeks, were examined before and after treatment with interferon and ribavirin. Data were compared to 10 patients with non-alcoholic fatty liver disease (NAFLD) used as controls. Results: A significant reduction of body fat (BF, p&lt;0.05) and body cell mass (BCM, p&lt;0.005) was found after treatment of the patients with chronic hepatitis C–irrespective of their genotype. Mean PA values for patients with genotype 3 decreased from 5.97 to 5.39 and for patients with genotype 1 from 5.28 to 5.15, respectively. Interestingly, reduction in PA was clinically more often accompanied with episodes of flu-like syndromes, fatigue, and reduced appetite. Patients with NAFLD demonstrated a significant reduction in body fat and an increase in total body water (TBW). No coherence was found between the BIA-measurements and standard laboratory parameters. Conclusion: BIA can offer a more sophisticated discrimination of the body composition including BF, BCM, and TBW. Moreover, reduction of phase angle was associated with more adverse effects. Therefore, phase angle determined by BIA allows a more valuable application in patients with hepatitis C under antiviral treatment.

Nutrition Status and Pressure Ulcer: What We Need for Nutrition Screening

Pressure ulcers (PU) and malnutrition exist in elderly hospitalized patients as a significant and costly problem. The aim of the study was to compare different screening tools to assess nutrition status and to verify them for usage in clinical routine. Nutrition status (body mass index [BMI], Mini Nutritional Assessment [MNA], weight loss) was determined in 484 (326 female/158 male) multimorbid elderly patients with mean age of 79.6 +/- 7.6 (80.9 +/- 7.4 female/76.9 +/- 7.4 male) years. Bioelectrical impedance analysis (BIA; Nutrigard 2,000-M) was used for evaluation of body composition. Activities of daily living (ADL) were measured with the Barthel Index. PUs were divided into stages I-IV (European Pressure Ulcer Advisory Panel [EPUAP]) and were assessed by the Norton scale. The prevalence of PU was 16.7%, with a median Norton scale of 20 (range, 17-24). According to MNA, 39.5% of the PU patients were malnourished, and 2.5% were well nourished. By contrast, 16.6% of the non-PU patients were malnourished, and 23.6% were well nourished. BMI decreased significantly in PU patients (p < .008). BIA resulted in no significant resistance and reactance but in a significant reduction of phase angle in PU. According to a significantly reduced body cell mass and lean body mass in PU patients, the ADL decreased in these patients, too. Furthermore, we analyzed a significant effect of age, ADL, MNA, BMI, phase angle, and body cell mass on the Norton scale. The MNA as a screening and assessment tool is easy to use to determine the nutrition status in multimorbid geriatric patients with PU. Further studies are needed to show an improved outcome of PU healing if evaluation of nutrition status is part of routine clinical practice in multimorbid elderly risk patients within the first day after admission.

A Technique for the Standing Phase-Angle Reduction in Power System Restoration

Blackout occurrences could cause devastating circumstances in power systems. Experience shows that the execution of power system restoration would require certain expertise and understanding of power system characteristics. One of the critical issues in power system restoration is the possible excessive phase angle difference between two buses which are to be connected by a transmission line. If the standing phase-angle is larger than the synchrocheck relay setting, then the circuit breaker would not be allowed to close. Correspondingly, instability could result in power systems if an attempt is made to force the closing of the loop. This article describes a simple and reliable approach to reduce the standing phase-angle difference. This approach is based on the rescheduling of power generation to achieve the desired reduction in standing phase-angle. The proposed approach is much more reliable than the time consuming method of trial and error that is being prescribed in practice. The results of the application of the proposed approach on the IEEE 118-bus system are presented and discussed.

New approach to standing phase angle reduction for power system restoration

AbstractDuring power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. These angles may occur across a tie line between two systems or between two connected subsystems within a system. In case of large Standing Phase Angle (SPA) difference the synchro‐check relay does not allow closing of the breaker for this line. Therefore, this excessive SPA has to be reduced before attempting to connect the line. In this paper a new and fast method for reducing SPA is presented. For this purpose, the standing phase angle difference between two specific buses is represented in terms of sensitivity factors associated with the change in active power generations and consumption at the buses. Then, the proposed method reschedule generation of selected units or shed load of selected buses to reduce excessive SPA difference between two buses based on sensitivity factors.

An algorithm for standing phase angle reduction for power system restoration

During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. In case of large standing phase angle (SPA) difference the synchrocheck relay does not allow closing of the breaker for this line. Therefore, this SPA has to be reduced before attempting to connect the line. In this paper a new and fast method for reducing SPA is presented. For this purpose, the standing phase angle difference between two specific buses is represented in terms of sensitivity factors associated with the change in real power injections at the buses. The proposed method will act as a direct help for reducing excessive SPA difference between two buses to an acceptable limit.