In order to improve the efficiency and ensure the security of power supply used in a mine, this paper mainly studies the quasi-resonant flyback secondary power supply and analyzes its operational principles based on the requirements of soft-switching technology. In accordance with the maximum energy of a short-circuit and the request of maximum output voltage ripple, this paper calculates the spectrum value of the output filter capacitor and provides its design and procedures to determine the parameters of the main circuit of power supply. The correctness and availability of this theory are eventually validated by experiments.
Anatomical variations of the inferior vena cava, including the double inferior vena cava or isolated left inferior vena cava, are uncommon and of great clinical importance. Inferior vena cava variations signify predisposition to deep vein thrombosis and may complicate retroperitoneal surgeries including abdominal aortic surgery. Failure to recognize such variations may predispose a patient to life- threatening complications. This prospective anatomical study assessed 129 cadavers for variations of the inferior vena cava. One of the 129 cadavers (0.78%) possessed a double inferior vena cava and none (0%) possessed an isolated left inferior vena cava. The left-sided inferior vena cava was of a larger diameter than that of the right-sided inferior vena cava — opposite of what would be seen in a Type III duplication. Therefore, this observation expands the three-type classification system to include a Type IV duplication.
B a c k g r o u n d: Today no established biomarkers are available for the early diagnosis of takotsubo syndrome and its differentiation from ST-segment elevation myocardial infarction. We hypothesized that copeptin and copeptin/NT-proBNP ratio may serve a routine marker combination for non-invasive differentiation.
M e t h o d s: The study compared the serum concentrations of copeptin, troponin I (TnI) and NT-proBNP in 19 consecutive women diagnosed with takotsubo syndrome according to the Mayo Clinic criteria and 10 consecutive women diagnosed with ST-segment elevation myocardial infarction.
R e s u l t s: Copeptin concentrations were significantly lower in patients with takotsubo syndrome than in patients with ST-segment elevation myocardial infarction. The diagnostic accuracy to distinguish takotsubo syndrome from ST-segment elevation myocardial infarction is highest for copeptin/NTproBNP ratio, copeptin/TnI at admission ratio and copeptin alone (AUC 0.8713, 0.8538, 0.8480, respectively).
C o n c l u s i o n s: The serum copeptin to NTproBNP ratio could be an additional tool in the non-invasive differentiation between takotsubo syndrome and ST-segment elevation myocardial infarction. However, further researches are needed.
The article provides a theoretical basis for a method allowing to calculate probability of effects of electric shock, as well as a method for determining probabilistic characteristics of random touch current values and of human body impedance in a person who suffered from specific effects of electric shock. Results of example calculations are presented, including probabilities of occurrence of sensory symptoms, exceeding the letgo threshold, and development of ventricular fibrillation, as well as probabilistic characteristics of random touch current values and of impedance of human body in people who experienced specific effects of electric shock.
Ozonation is a heterogeneous process of chemical absorption often controlled by a gas-liquid mass transfer rate. This paper presents the results of kinetics in a reaction between phenylphenol isomers and ozone. The degradation of phenylphenol isomers during ozonation proceeds quite fast. In order to avoid the influence of mass transfer limitation the kinetics experiments were conducted in a homogenous liquid-liquid system. The second-order rate constants were determined using classical and competition methods, which are especially recommended for fast reactions. The determined rate constants at pH 2 using the two different methods are almost the same. The increase of pH causes an increase of rate constants for the reaction of phenylphenol isomers with ozone.
I n t r o d u c t i o n: Complications occurring aft er neurosurgical procedures which lead to reoperations are associated with poor treatment outcomes. Th e aim of our study was to establish predictive factors of unplanned early reoperations aft er intracranial meningioma removal.
Ma t e r i a l s a n d M e t h o d s: We retrospectively analyzed 177 patients who underwent craniotomy due to an intracranial meningioma. Early reoperation was defi ned as reoperation during the same hospital stay. We used a χ2 test for proportional values and t-test and Mann-Whitney U tests as appropriate for continuous variables. To determine the potential predictors of early reoperation we used univariate and multivariate logistic regression analyses.
R e s u l t s: A total of 13 (7.34%) patients underwent unplanned early reoperation. Th ese patients underwent retrosigmoid craniotomies (25.00% vs. 6.40%; p = 0.047), suff ered from ischemic heart disease (66.67% vs. 6.64%; p <0.01) and atrial fi brillation (60.00% vs. 6.25%; p <0.01), were receiving heparin (50.00% vs. 6.74%; p <0.01) and anticoagulants (66.67% vs. 6.21%; p <0.01) signifi cantly more oft en than the general study population. In multivariate logistic regression analysis anticoagulant use (OR: 31.463; 95% CI: 1.139–868.604; p = 0.04) and retrosigmoid craniotomy (OR: 6.642; 95% CI: 1.139–38.73; p = 0.034) remained independently associated with a higher risk of early reoperation.
C o n c l u s i o n s: Patients who underwent retrosigmoid craniotomy, those with a history of ischemic heart disease or atrial fi brillation and those who take heparin or anticoagulants are more likely to require early reoperation. Retrosigmoid craniotomy and anticoagulant use are independent risk factors for early reoperation.
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