MOSFE-Capacitor Silicon Carbide-Based Hydrogen Gas Sensors.

The features of the wide band gap SiC semiconductor use in the capacitive MOSFE sensors' structure in terms of the hydrogen gas sensitivity effect, the response speed, and the measuring signals' optimal parameters are studied. Sensors in a high-temperature ceramic housing with the Me/Ta2O5/SiCn+/4H-SiC structures and two types of gas-sensitive electrodes were made: Palladium and Platinum. The effectiveness of using Platinum as an alternative to Palladium in the MOSFE-Capacitor (MOSFEC) gas sensors' high-temperature design is evaluated. It is shown that, compared with Silicon, the use of Silicon Carbide increases the response rate, while maintaining the sensors' high hydrogen sensitivity. The operating temperature and test signal frequency influence for measuring the sensor's capacitance on the sensitivity to H2 have been studied.

Surgical Management of Aorto-Ventricular Tunnel. A Multicenter Study.

Aorto-ventricular tunnel (AoVT), a rare congenital anomaly, is a channel originating in the ascending aorta just above the sinotubular junction and leading to the cavity of the left ventricle (AoLVT), or, rarely, the right (AoRVT). This study reviews our collective 30-year experience with the surgical treatment of AoVT. Data were submitted by 15 participating centers on 42 patients who underwent correction of AoVT between 1987 and 2018. Of these, 36 had AoLVT, and 6 AoRVT. The tunnel originated above the right coronary sinus in 28 (77.8%) patients. For AoLVT, most operations were performed early (median age 25 days, range: 1 day-25 years). In contrast, AoRVT was diagnosed and repaired later (median age 6 years, range: 1 month-12 years). Surgically important coronary ostial displacement was common. Patch closure of the aortic orifice only was the commonest surgical repair for AoLVT (23 patients), while in AoRVT, both orifices or only the ventricular one was closed. Aortic valvar insufficiency, severe or moderate, coexisted in 11 (30.5%) patients with AoLVT, and aortic valvuloplasty was performed in 8, mainly due to aortic valve stenosis. Aortic valvar insufficiency at discharge ranged from trivial to mild in almost all patients. Early mortality was 7.14%, with 3 patients with AoLVT succumbing to cardiac failure. There were 2 early reoperations and 1 late death. AoVT is a rare malformation. AoLVT usually necessitates surgery in early life. AoRVT is rarer, diagnosed and repaired later in life. Surgical repair by patch closure, with concomitant aortic valve repair as needed, is associated with good results.

Comparative Assessment of Excretion of Milk from Two Breast Pumps with Different Vacuum Strength and Duration.

BACKGROUND: Breastfeeding is the best source of food for the newborn. In a situation wherein it is not possible to breastfeed a baby, it may be necessary to express milk from the mother's breast using a breast pump. To achieve lactation success before a baby's suckling can ensure the effective extraction of milk, breast pumps must meet specific biomechanical requirements. However, the parameters of the vacuum stimuli by which milk is expressed remain nonoptimized. SUBJECTS AND METHODS: Forty-nine lactating women of 21-30 years of age who volunteered to be included in this study were examined. Women had been lactating and breastfeeding normally for 6-7 days. A new method was developed to compare the amount of milk ejected by vacuum pulses of different amplitudes or duration. RESULTS: It was found that for most nursing women, the vacuum stimuli with amplitude of about 190 mm Hg, duration of 0.7 second, and frequency of 1 impulse/s are optimal for removing milk from the breast of a woman. CONCLUSIONS: Optimization of the amplitude and duration of the vacuum stimuli increased the efficacy of the breast pump.

The Mechanics of Breast Pumping: Compression Stimuli Increased Milk Ejection.

BACKGROUND: The use of breast pumps with a compression component has shown their higher efficacy compared with vacuum pumps. However, the direct role of the compression stimulus is not sufficiently proven in the removal of milk from the main milk ducts of the breast. The aim of this study was to determine the contribution pulsating compression component of the breast pump has on total volume milk ejection by vacuum and compression stimuli. SUBJECTS AND METHODS: Twenty-four lactating women of 21-30 years of age, who volunteered to be included in this study, were examined. Experimental breast pump with vacuum and compressive components were used to express breast milk. RESULTS: It was found that volume milk ejection together with vacuum and compression stimuli was 10-46% more than expressing only with vacuum stimuli. Average values were 40.5% ± 5% for expression only with vacuum stimuli and 59.5% ± 5% for expression with vacuum and compression stimuli. CONCLUSIONS: Compression stimuli increased the efficacy of the breast pump, which is not only due to the effective formation milk ejection reflex but also directly to an additional squeezing of milk from the breast.

Early Diagnosis and Repair of Double Saccular Aneurysms of the Aortic Arch Associated With Aortic Coarctation in an Infant With Loeys-Dietz Syndrome.

Multiple saccular aneurysms of the thoracic aorta in neonates and infants are exceedingly rare. An association of these aneurysms with Loeys-Dietz syndrome (LDS) in older age-groups is well known. This case report describes the diagnosis and subsequent successful repair of aortic coarctation associated with double saccular aneurysms of the thoracic aorta in patient with LDS during the first year of life.

Deep impact of the template on molecular weight, structure, and oxidation state of the formed polyaniline.

In this work we find that polyaniline (PANI), synthesized by aniline chemical polymerization at a surface of template polycarbonate (PC) particles, is significantly different in molecular weight, structural order, oxidation state, and conductivity from a neat PANI. Molecular weight of the PANI phase in the composite (Mw = 158,000) is 1.6 times higher than that of the neat PANI synthesized in the absence of the template particles. Moreover, XRD analysis shows that crystallinity of the PANI phase in the composite is three times higher than that of the neat PANI. Raman spectroscopy indicates that the oxidation level of PANI in the PC/PANI composite is lower than that of the neat PANI. These noticeable changes of the PANI phase properties suggest specific interactions of reagents in the polymerization medium and formed PANI with the template phase as well as an orientation effect of the latter surface. FTIR spectroscopy reveals that hydrogen bonding in the neat doped PANI is weaker than one between -NH- of PANI and C═O of PC at their interface. The discovered differences are supported by the fact that conductivity of the PANI phase in the composite is more than three times higher than that of the neat PANI.

Surgical correction of tetralogy of Fallot with unilateral absence of pulmonary artery.

BACKGROUND: Tetralogy of Fallot with unilateral absence of the pulmonary artery is a rare congenital heart defect that still represents a surgical challenge. The purpose of this study is to summarize our experience of surgical treatment of this complex lesion. METHODS: From 1983 to 2003, 27 patients with tetralogy of Fallot and unilateral absence of the left (n = 25) or right (n = 2) pulmonary artery underwent different surgical interventions. The age of patients ranged from 40 days to 37 years (median, 5.3 years). Pulmonary arterial Nakata index and Nakata index Z-score were used for the quantitative assessment of the contralateral pulmonary artery. Twenty patients underwent various palliative procedures, namely Blalock-Taussig or Gore-Tex shunt, transluminal balloon pulmonary valvuloplasty, and reconstruction of right ventricular outflow tract without ventricular septal defect closure. At a median interval of 3.6 years after palliation, 13 patients underwent complete repair of tetralogy of Fallot. In the other 7 patients, complete repair was performed as a primary intervention. RESULTS: Hospital mortality after palliation and after a complete repair was the same and reached 5%. Sixteen patients with the Nakata index greater than 200 mm2/m2 and Z-score greater than -4 survived after a complete repair. One of 4 patients with Nakata index less than 200 mm2/m2 and Z-score less than -4 died after surgery. CONCLUSIONS: Majority of patients with tetralogy of Fallot and unilateral absence of the pulmonary artery require palliative intervention as a first step of surgical treatment. Nakata index greater than 200 mm2/m2 and Nakata index Z-score greater than -4 are criteria for a successful complete repair.

The arterial switch operation in Europe for transposition of the great arteries: a multi-institutional study from the European Congenital Heart Surgeons Association.

OBJECTIVES: This study analyzes the results of the arterial switch operation for transposition of the great arteries in member institutions of the European Congenital Heart Surgeons Association. METHODS: The records of 613 patients who underwent primary arterial switch operations in each of 19 participating institutions in the period from January 1998 through December 2000 were reviewed retrospectively. RESULTS: A ventricular septal defect was present in 186 (30%) patients. Coronary anatomy was type A in 69% of the patients, and aortic arch pathology was present in 20% of patients with ventricular septal defect. Rashkind septostomy was performed in 75% of the patients, and 69% received prostaglandin. There were 37 hospital deaths (operative mortality, 6%), 13 (3%) for patients with an intact ventricular septum and 24 (13%) for those with a ventricular septal defect (P < .001). In 36% delayed sternal closure was performed, 8% required peritoneal dialysis, and 2% required mechanical circulatory support. Median ventilation time was 58 hours, and intensive care and hospital stay were 6 and 14 days, respectively. Although of various preoperative risk factors the presence of a ventricular septal defect, arch pathology, and coronary anomalies were univariate predictors of operative mortality, only the presence of a ventricular septal defect approached statistical significance (P = .06) on multivariable analysis. Of various operative parameters, aortic crossclamp time and delayed sternal closure were also univariate predictors; however, only the latter was an independent statistically significant predictor of death. CONCLUSIONS: Results of the procedure in European centers are compatible with those in the literature. The presence of a ventricular septal defect is the clinically most important preoperative risk factor for operative death, approaching statistical significance on multivariable analysis.