Effect Of Shunt Research Articles

An electromagnetic actuator for the medium voltage vacuum contactor

A review of the use of mono- and bistable unpolarized and polarized electromagnets in medium voltage contactors is presented. The analysis of the design features of electromagnetic actuators is carried out and recommendations for their improvement are developed. A new design of a bistable actuator based on a polarized monostable electromagnet with a return spring, its principle of operation are considered. Due to the use of a ring-shaped element of a non-magnetic material between the case and the core of the electromagnet, it is possible to reduce the effect of shunting without increasing the axial size of the electromagnet. For the prototype, the magnetic fields are calculated in the off position, with a gap of 12 mm between the armature and the fixed part of the magnetic core and in the on position, with the armature pressed. The effect of a ring ferromagnetic shunt on the traction force at the released and pressed armature is determined. The electromechanical control system of a single-coil bistable actuator is developed. Experimental investigations of a bistable actuator based on a polarized monostable electromagnet with a return spring are carried out. The time for switching on and off of the new vacuum contactor is set.

Laboratory and technological electric-arc plasma generators

The constructive schemes of electric-arc plasmatrons were analyzed by energy and erosion characteristics. The effect of arc shunting on plasmatron classification is presented. The effectiveness of barrier cooling in plasmatron channel with a sectioned interelectrode insert is determined. The criteria for the efficiency of tubular electrodes in plasmatrons with gas-vortex stabilization of an arc discharge are given. The role of vacuum plasmatrons in creation of plasma-vacuum electric furnaces is shown.

Risk factors for hepatic veno-occlusive disease caused by Gynura segetum: a retrospective study

BackgroundHepatic veno-occlusive disease (HVOD) caused by Gynura segetum has been increasingly reported in China in recent years. The aim of this retrospective study was to identify independent prognostic markers for survival in patients with Gynura segetum-induced HVOD and to evaluate the effect of anticoagulants and transjugular intrahepatic portosystemic shunt (TIPS) on survival rate.MethodsClinical data including symptoms, signs, imaging characteristics, laboratory test results, results of liver tissue biopsies, type of treatment during follow-up and clinical outcomes were collected. Univariate, multivariate and time-dependent Cox regression analyses were performed.ResultsSurvival rates were 91% (95% confidence interval [CI], 82–95%), 64% (95% CI, 53–69%) and 57% (95% CI, 51–65%) at 1, 3 and 60 months, respectively. Total bilirubin, albumin and hepatic encephalopathy were independent prognostic markers of survival. Anticoagulants were administered to 76% of the patients. Among 75 patients treated with anticoagulants, 49 patients (65.3%) were cured, whereas 26 patients (34.7%) died; the cure rate in anticoagulant-treated patients was higher than that of those not treated with anticoagulants (χ2 = 9.129, P = 0.004). Cure rate of the anticoagulation + TIPS treatment group was 64.3%, which was also higher than that of the non-anticoagulation group; however, this was not significantly different (χ2 = 3.938, P = 0.096).ConclusionsThe presence of hepatic encephalopathy, serum bilirubin and albumin levels were major prognostic factors for Gynura segetum-induced HVOD. Anticoagulation therapy significantly increased the cure rate; however, TIPS treatment did not have a beneficial effect on the cure rate.

Early outcome and risk factors analysis of Blalock-Taussig shunt

Objective To investigate the early curative effect of Blalock-Taussig(B-T) shunt and summarize the key point in its post-operative intensive care, analyze the related risk factor of its mortality. Methods We collected 71 patients who received B-T shunt in Shanghai Children′s Medical Center from June 2015 to June 2017.All of 71 cases were divided into neonates group (25 cases) and non-neonate group(46 cases). All patients were operated through median sternotomy, 19 were emergency cases, in which 15 cases were neonates.Eight cases used cardio-pulmonary bypass in our study, in which 4 cases were neonates.Twenty-nine cases received ductus ligation in total 34 patients with patent ductus arterious.Percutaneous heparin was immediately administered after operation as an anticoagulation therapy.Relative large dosage inotropic agents was used after sufficient volume infusion in order to guarantee diastolic pressure higher than 35 mmHg(in neonates >30 mmHg, 1 mmHg=0.133 kPa). Ventilator parameter was adjusted to obtain appropriate flow distribution between pulmonary and systemic circulation.In order to avoid excessive pulmonary flow, the target PO2 was set between 40~45 mmHg. Results Oxygen saturation elevated by 15% after operation in all 71 cases.Average mechanical ventilation time was 92 hours, mean inotropic agents score was 17.There were 6 dead cases, mortality was 8.5%.In neonates, 4 cases dead, mortality was 16.0%.There was no significant difference in ventilation time, ICU retention day and mortality between neonates group and non-neonates group.The logistic regression analysis showed that the body weight and ratio between the shunt conduit diameter and body weight (mm/kg) were the risk factors for early post-operative mortality[body weight: 2 500~3 500 g: OR=6.729, 95%CI=1.373~17.131; ≤2 500 g: OR=7.832, 95%CI=2.563~28.325.the ratio between the shunt conduit diameter and body weight (mm/kg): 1.10~1.15: OR=4.204, 95%CI=1.195~23.926; ≥1.15: OR=3.981, 95%CI=1.195~12.926]. Conclusion B-T shunt is still a high risk operation although it is a palliative method.Low body weight and bigger diameter conduit are the significant factors related to its mortality.Strict control of the systemic and pulmonary flow ratio is the key point in the post-operation intensive care. Key words: Blaclock-Taussig shunts; Neonates; Palliative operation; Congenial heart disease

The surgical treatment in adults with idiopathic normal pressure hydrocephalus

Objective: To investigate the effect of Ventriculoperitoneal shunt (VPS)in adult patients with idiopathic normal pressure hydrocephalus (iNPH). Methods: The patients with idiopathic normal pressure hydrocephalus were reviewed, who were admitted into the Peking union medical college hospital from October 2010 to October 2016.The patients treated via VPS were retrospectively analyzed by collecting the data including clinic features, iNPH score and imaging data. Results: 33 patients were included in the group.3 months after operation, the iNPH scores were significantly decreased (3.0±1.0 vs 6.0±2.5, P<0.01), and there were no difference among 3 month, 6 month and 12 month post operation.The Evans index and the width of the three ventricles were also significantly decreased.1 patient suffered from subdural hematoma and no other complications such as infection, obstruction or death occurred. Conclusions: VPS is an effective treatment approach of iNPH and multidisciplinary team is the key in diagnosis.

Effect of Proximal Splenorenal Shunt on Intraoperative Portal Venous Pressure and Its Correlation with Clinical Outcomes

Proximal splenorenal shunt (PSRS), commonly performed for non-cirrhotic portal hypertension (NCPH), diminishes elevated portal venous pressure (PP) and prevents its sequelae. The change in PP after PSRS and its correlation with clinical outcome is largely unknown. Twenty-four patients who underwent PSRS for NCPH were evaluated prospectively. PP was measured after completion of splenectomy and after PSRS. Follow-up for 3 months was done to assess shunt patency and other relevant clinical variables. Change in PP and shunt patency were correlated with clinical outcome. Seventeen patients had extrahepatic portal vein obstruction (EHPVO) and seven had non-cirrhotic portal fibrosis (NCPF). There was a significant decrease in PP (median10 mmHg) after PSRS (p 0.05). Shunt patency showed significant correlation with splenic vein diameter (p = 0.018), shunt diameter (p = 0.024), blood flow across shunt (p = 0.023), change in variceal grade (p = 0.032), and need for endotherapy (p = 0.002). PP decreases after PSRS in patients with NCPH. However, this does not correlate with clinical outcome. A patent shunt at 3 months correlated with most of these variables.

Measurement and Analysis of Low Frequency Magnetic Shielding Performance of Open-Cell Nickel Foam

Low frequency magnetic field in the range from 10 to 500 kHz is between very-low and mid-high frequencies, mainly coming from industrial equipments such as antenna, battery, inverter, etc. In some shielding applications simultaneously demanding for ventilation and cooling, high-performance shielding materials with a porous structure are necessary. However, the investigation of these materials in this band was rarely reported. Open-cell nickel foam has excellent electrical conductivity and magnetic permeability, which makes it a potential new kind of shielding material in the field of low frequency magnetic shielding. It is generally believed that, in this band, materials shield the magnetic field mainly through two mechanisms, i.e., flux shunting and eddy current cancellation. With the equation of shielding effectiveness (SE) for a cylindrical shell, SEs of copper foil and Permalloy were calculated. The results indicated that the effect of flux shunting can be ignored, which was further verified by the results of Helmholtz coil test. Thus, only eddy current cancellation mechanism was considered to establish a shielding model, in which the flat open-cell nickel foam was assumed to be a group of coils and the eddy current was assumed to flow along the conductive paths composed of the coils. The prediction of the model was verified by the measured results of a window test method. Both the experimental and theoretical results revealed that, SE is enhanced with the decrease of the average pore size of the foam because the number of conductive paths in the foam increases. In addition, the calculated results of SE indicated that the open-cell nickel foam has no obvious superiority compared to a fully dense nickel strip of the same areal density. However, the structure characteristics of open-cell foam make it definite to find applications simultaneously asking for shielding, ventilating and cooling.

Ventriculoperitoneal shunts in non-HIV cryptococcal meningitis

BackgroundPersistent and uncontrollable intracranial hypertension (ICH) and difficulty in reducing Cryptococcus count are severe problems in cryptococcal meningitis (CM) patients. The therapeutic effects of ventriculoperitoneal shunts (VPS) in non-HIV CM patients are not fully known, and the procedure is somewhat unusual. Here, our study offers a review to investigate the role of VPS in non-HIV CM.MethodsWe retrospectively collected data on 23 non-HIV CM patients with and without ventriculomegaly from 2010 to 2016. Their demographic data, clinical manifestations, cerebrospinal fluid (CSF) features and outcomes were analysed.ResultsWe found that non-HIV CM patients without ventriculomegaly were older, had earlier treatment times and had shorter symptom durations than CM patients with ventriculomegaly. In both groups, headache, vomiting, fever and loss of vision were the most common clinical features. CSF pressure and Cryptococcus count were significantly decreased after operation. VPS could provide sustained relief from ICH symptoms such as headache. 13% of patients had poor outcomes because of serious underlying disease, while 87% of patients had good outcomes.ConclusionsThe use of a VPS is helpful in decreasing ICH and fungal overload in non-HIV CM patients, and VPS should be performed before CM patients present with symptoms of severe neurological deficit.

Tu1478 - The Effects of a Transjugular Intrahepatic Portosystemic Shunt on the Diagnosis of Hepatocellular Cancer

Tu1478 - The Effects of a Transjugular Intrahepatic Portosystemic Shunt on the Diagnosis of Hepatocellular Cancer

Effect Of Av Shunt On Cardiac Function in Patient with Fair Systolic Function

Cardiovascular disease is the leading cause of the death in patients receiving chronic renal replacement therapy,Arteriovenous fistulas [AVFs] have superior longevity, lower infection and mortality rates and are associated with lowercost, and hence have become the vascular access of choice for patients needing dialysis.The aim of this study is to assessthe effect of AVF on cardiac function in patients with fair systolic function in patients with ESRD .This is a prospective,non-controlled , observational study that will include 20 patients who will been admitted to Heliopolis Hospital withESRD and treated with hemodialysis and cardiac function will be assessed by echocardiography preoperative of AVFcreation and 3 months postoperative There was statistically significant difference in diastolic dysfunction grades betweenbefore and after AVF. there is an effect of AVF on cardiac function in patients with fair systolic function in patients withESRD as there was statistically significant difference in diastolic dysfunction grades between before and after AVF.

Effect of Local Shunting on the Electrical Mismatch Losses in Industrial Silicon Photovoltaic Modules

Effect of Local Shunting on the Electrical Mismatch Losses in Industrial Silicon Photovoltaic Modules

Imaging, microscopic analysis, and modeling of a CdTe module degraded by heat and light

Photoluminescence (PL), electroluminescence (EL), and dark lock-in thermography are collected during stressing of a CdTe module under one-Sun light at an elevated temperature of 100°C. The PL imaging system is simple and economical. The PL images show differing degrees of degradation across the module and are less sensitive to effects of shunting and resistance that appear on the EL images. Regions of varying degradation are chosen based on avoiding pre-existing shunt defects. These regions are evaluated using time-of-flight secondary ion-mass spectrometry and Kelvin probe force microscopy. Reduced PL intensity correlates to increased Cu concentration at the front interface. Numerical modeling and measurements agree that the increased Cu concentration at the junction also correlates to a reduced space charge region.

Effect of temporary vascular shunting as a previous intervention on lower extremity arterial injury: Single center experiences in the Syrian Civil War.

The goal of this retrospective study was to clarify the effect of using temporary vascular shunt (TVS) as a previous intervention. A total of 96 cases with war-related lower extremity arterial injury and surgically treated between October 2013 and March 2016 were included in the study. The patients were divided into two groups: those in which TVS was performed as a previous intervention on admission (TVS group, n=24) and those in which compression, tourniquet, and ligation/clampage were performed as a previous intervention on admission (non-TVS group, n=72). In comparing injury pattern, there was no difference between the two groups. In addition, mean hematocrit level, mean systolic blood pressure, the incidence of concomitant vein injury, nerve injury, soft tissue damage, and bone injury were similar in both groups. The overall amputation rate was 19%. There were a total of 18 amputations, with 1 (4%) in the TVS group and 17 (24%) in the non-TVS group. The difference on amputation rate was statistically significant. The mean values of the mangled extremity severity score (MESS) were 6.45 in the TVS group and 7.44 in the non-TVS group. The overall mean MESS was 7.1. The duration of ischemia (DoI) was 4.84+-1.84 h in the TVS group and 5.95+-1.92 h in the non-TVS group. These differences in MESS and DoI were statistically significant. We think that it may be beneficial for patients to consider a TVS to reduce DoI and gain time for surgical revascularization. As a result, the present study demonstrates that the use of TVS may successfully serve as a bridge between initial injury and definitive repair with a reduction in amputation rates.

Ascites

Ascites is the most common cause of decompensation in cirrhosis, and 5% to 10% of patients with compensated cirrhosis develop ascites each year. The main factor of ascites formation is renal sodium retention due to activation of the renin-angiotensin-aldosterone system and sympathetic nervous system by the reduced effective volume secondary to splanchnic arterial vasodilation. Diagnostic paracentesis is indicated in all patients with a new onset of grade 2 or 3 ascites and in those admitted to hospital for any complication of cirrhosis. A serum-ascites albumin gradient of ≥1.1 g/dL indicates portal hypertension with an accuracy of approximately 97%. Sodium restriction, diuretics, and large volume paracentesis are the mainstay of treatment in grade 1 to 3 ascites. The refractoriness of ascites is associated with a poor prognosis with a median survival of approximately six months. Repeated large volume paracentesis plus albumin is the first line treatment, and liver transplantation is recommended in patients with refractory ascites. A careful selection of patients is also important to obtain the beneficial effects of transjugular intrahepatic portosystemic shunts in refractory ascites. This review details the recent diagnosis and treatment of cirrhotic ascites.

Lumboperitoneal shunts for the treatment of post-traumatic hydrocephalus

Objective: To assess the effectiveness and safety of lumboperitoneal shunt for treatment of post-traumatic hydrocephalus (PTH). Methods: A retrospective analysis of medical records of patients with lumboperitoneal shunts admitted in Shanghai Tenth People's Hospital from January 2014 to March 2017 was done. Experience with lumboperitoneal shunt placement for PTH was reviewed. The diagnosis of PTH was based on ventricular enlargement with the Evans’ index (EI>0.3) before shunt implantation. Patients were evaluated for improvements in Glasgow Coma Scale (GCS), Glasgow Outcome Scale (GOS), and EI after shunt placement. Results: Totally, the study included 34 PTH patients with the average age of 49.32 years (range: 9-67 years). The average follow-up period was (3.9±3.5) months. Before lumboperitoneal shunt, the GOS score was (4±1), the GCS score was (8.53±3.38), and the EI score was (0.40±0.08). After shunt implantation, the GOS score was (3±1), the GCS score was (10.29±3.15), and the EI score was (0.34±0.13), respectively (P 2 and 8 patients GCS improvement=1), 21 (61.76%) patients had EI improvement (18 patients with EI

Transjugular intrahepatic portosystemic shunt: impact on systemic hemodynamics and renal and cardiac function in patients with cirrhosis.

Transjugular intrahepatic portosystemic shunt (TIPS) alleviates portal hypertension and possibly increases central blood volume (CBV). Moreover, renal function often improves; however, its effects on cardiac function are unclear. The aims of our study were to examine the effects of TIPS on hemodynamics and renal and cardiac function in patients with cirrhosis. In 25 cirrhotic patients, we analyzed systemic, cardiac, and splanchnic hemodynamics by catheterization of the liver veins and right heart chambers before and 1 wk after TIPS. Additionally, we measured renal and cardiac markers and performed advanced echocardiography before, 1 wk after, and 4 mo after TIPS. CBV increased significantly after TIPS (+4.6%, P < 0.05). Cardiac output (CO) increased (+15.3%, P < 0.005) due to an increase in stroke volume (SV) (+11.1%, P < 0.005), whereas heart rate (HR) was initially unchanged. Cardiopulmonary pressures increased after TIPS, whereas copeptin, a marker of vasopressin, decreased (-18%, P < 0.005) and proatrial natriuretic peptide increased (+52%, P < 0.0005) 1 wk after TIPS and returned to baseline 4 mo after TIPS. Plasma neutrophil gelatinase-associated lipocalin, renin, aldosterone, and serum creatinine decreased after TIPS (-36%, P < 0.005; -65%, P < 0.05; -90%, P < 0.005; and -13%, P < 0.005, respectively). Echocardiography revealed subtle changes in cardiac function after TIPS, although these were within the normal range. TIPS increases CBV by increasing CO and SV, whereas HR is initially unaltered. These results indicate an inability to increase the heart rate in response to a hemodynamic challenge that only partially increases CBV after TIPS. These changes, however, are sufficient for improving renal function. NEW & NOTEWORTHY For the first time, we have combined advanced techniques to study the integrated effects of transjugular intrahepatic portosystemic shunt (TIPS) in cirrhosis. We showed that TIPS increases central blood volume (CBV) through improved cardiac inotropy. Advanced echocardiography demonstrated that myocardial function was unaffected by the dramatic increase in preload after TIPS. Finally, renal function improved due to the increase in CBV. Recognition of these physiological changes significantly contributes to our clinical understanding of TIPS.

Techniques and long-term effects of transjugular intrahepatic portosystemic shunt on liver cirrhosis-related thrombotic total occlusion of main portal vein

Portal vein hypertension (PVH) in liver cirrhosis complicated with portal venous thrombosis (PVT) has been mainly treated with transjugular intrahepatic portosystemic shunt (TIPS). The clinical effects of TIPS have been confirmed, however, no large-scale studies have been focused on technical analyses and a long-term follow-up, especially on thrombotic total occlusion of main portal vein (MPV). To demonstrate critical techniques and clinical outcome of TIPS on liver cirrhosis-related thrombotic total occlusion of MPV, 98 patients diagnosed with liver cirrhosis related thrombotic total occlusion of MPV and treated with TIPS from January 2000 to January 2010 were retrospectively analyzed. Twenty-three (23.5%) patients had MPV (single site) thrombosis, 55 (56.1%) had multiple site-thrombosis (MPV and other), 17 (17.3%) had cavernous transformation of portal vein, and 3 (3.1%) had post-transplant thrombosis. The successful rate of TIPS was 90.7%, without any procedure-related deaths or severe complications. Mean portal pressure was dropped from 33.08 ± 1.38 mmHg preoperatively to 20.18 ± 0.83 mmHg postoperatively (p < 0.001). Collectively, TIPS is safe and effective in treating liver cirrhosis-related thrombotic total occlusion of MPV. This complex procedure requires combination of indirect portography and percutaneous transhepatic portal techniques to increase the rate of success.

Effectiveness of Transjugular Intrahepatic Portosystemic Shunt in Variceal Bleeding: An Audit from a Tertiary Care Center in North India

AbstractVariceal bleeding is one of the most feared complications of cirrhosis and portal hypertension. Transjugular intrahepatic portosystemic shunt (TIPS) is an effective minimally invasive option to achieve adequate decompression of the portal system. The aim of the study was to assess the efficacy and complications of TIPS in patients presenting with variceal bleed. It was a retrospective study done in a tertiary care center in North India in cirrhotic patients with acute or recurrent variceal bleed who underwent TIPS from April 2010 to October 2013. All the patients were followed up till April 2014. We could successfully implant TIPS in 100% of our patients with 100% success rate in controlling variceal bleeding immediately and during the follow-up period. Our primary patency rate was 94.5% and overall patency rate was 100%. Major TIPS-related complication was hepatic encephalopathy in 20% of patients; 7 of 22 patients died during the follow-up period. TIPS is a safe and effective procedure for control of acute or recurrent variceal bleed. Emerging evidence in favor of early TIPS is further going to expand its indication in variceal bleed. Hepatic encephalopathy was the major procedure-related complication in our study consistent with previous literature reports.

Cardiovascular Effects of a Transjugular Intrahepatic Portosystemic Shunt in Patients with Cirrhosis

Insertion of a transjugular intrahepatic portosystemic shunt (TIPS) has proven effective in alleviating complications to portal hypertension such as refractory ascites and variceal bleeding in patients with cirrhosis. Moreover, it increases survival in selected patient groups. However, TIPS also causes marked circulatory changes and a central concern has been whether this could negatively affect cardiac function. Therefore, this review aims to critically discuss our knowledge on cardiovascular effects of a TIPS in cirrhosis. These suggest that TIPS does not worsen cardiac function. Careful cardiac evaluation prior to TIPS is, however, a prerequisite in order to prevent cardiac complications after TIPS insertion. The focus on cirrhotic cardiomyopathy has raised the awareness on specific procedures such as TIPS. Thus, previous studies have demonstrated that TIPS seemingly worsens cardiac function with a negative effect on ascites clearance and survival. However, recent studies have not been able to establish this deleterious interplay and the overall frequency of cardiac failure after TIPS still remains low. Hence, TIPS seems to be safe with regard to cardiac function in patients with cirrhosis.

Ohmic shunts in two-terminal dual-junction solar cells with current mismatch

The impact of ohmic shunts on the current–voltage characteristics of single junction solar cells is well understood. Yet, for monolithic dual-junction solar cells, the effects of shunts have far less been investigated, especially if there is a current mismatch between the two sub cells. In this work, we investigate theoretically and experimentally how current–voltage characteristics of a monolithic GaAs/GaAs tandem solar cell depend on shunts in the top or the bottom sub cell, when either of this sub cells is current limiting. The open-circuit voltage of the device is observed to transition to the open-circuit voltage of the non-shunted sub cell as the shunting increases. In the same way, the fill factor is found to be more significantly affected when ohmic shunts occur in the current-limiting sub cell. Finally, as the current-limiting sub cell is shunted, the short-circuit current of the device is observed to transition to the short-circuit current of the non-current-limiting sub cell. These results allow identifying the shunted sub cell and enable characterization of ohmic shunts under current limiting conditions in dual-junction solar cells.