Thermophysical properties of the Ni-based alloy Nimonic 80A up to 2400 K

Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe, voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers and the radiance temperature of the sample with a pyrometer. These measurements allow to determine heat of fusion as well as heat capacity and electrical resistivity at initial geometry of Nimonic 80A as a function of temperature in the solid and in the liquid phase up to 2400 K.     

Cerebral air embolism after central venous catheter

Introduction of air into the arterial circulation can cause cerebral air embolism, leading to severe neurological deficits. A case is reported on a patient suffering from fatal cerebral air embolism after a subclavian vein catheter had been inserted. The risks associated with inserting and removing central venous catheters are described. Apart from the pathogenesis of a paradoxical air embolism in a patient with a right-to-left shunt due to a patent foramen ovale, air embolism can occur if a large amount of air traverses the pulmonary circulation. The ability of the pulmonary vasculature to filter air may be exceeded by a bolus injection of more than 30 ml air. Air embolism is suspected if acute neurological symptoms occur after inserting a central venous catheter. Echocardiography, especially transoesophageal echocardiography. Is highly sensitive in detecting air emboli in the ventricles. Treatment is effected with hyperbaric oxygen and standard measures of intensive-care medicine.     

Design and evaluation of current-mode image sensors in CMOS-technology

Three different current-mode-output CMOS image sensor structures comprising of a pixel cell and an appropriate readout circuit have been analyzed and compared with regard to their noise behavior, fixed-pattern noise (FPN), and the dynamic range. First, a standard integrating pixel cell with a readout circuit containing a voltage-to-current converter is proposed. Second, a pixel cell based on a switched current cell is analyzed. The third sensor cell uses a feedback loop to control the reverse bias voltage of the photodiode to reduce the settling time of the pixel cell and the influence of the photodiodes's dark current. The necessary amplifier is partly located in the pixel cell and partly in the readout circuit. In all sensors, correlated double sampling is used to suppress the FPN.     

Thermophysical Properties of a Chromium–Nickel–Molybdenum Steel in the Solid and Liquid Phases

Numerical simulation of vacuum arc re-melting, pressurized or protective electro-slag re-melting, and ingot casting have become quite important in the metal industry. However, a major drawback of these simulation techniques is the lack of accurate thermophysical properties for temperatures above 1,500 K. Heat capacity, heat of fusion, density, and thermal conductivity are important input parameters for the heat transfer equation. Since, direct measurements of thermal conductivity of alloys in the liquid state are almost impossible, its estimation from electrical conductivity using the Wiedemann–Franz law is very useful. The afore-mentioned thermophysical properties of several steels are investigated within the context of an ongoing project. Here, we present a full set of thermophysical data for the chromium–nickel–molybdenum steel meeting the standard DIN 1.4435 (X2CrNiMo18-14-3); these values will be used by our partner to simulate various re-melting and solidification processes. Wire-shaped samples of the steel are resistively volume-heated, as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe. The voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers, the temperature of the sample with a pyrometer, and the volumetric expansion of the wire with a fast acting CCD camera. These measurements enable the heat of fusion, the heat capacity, and the electrical resistivity to be determined as a function of temperature in the solid and liquid phases. The thermal conductivity and thermal diffusivity are estimated via the Wiedemann–Franz law.     

Right intra-atrial catheter placement for hemodialysis in patients with multiple venous failure

The purpose of this study is to evaluate the efficacy and safety of direct right atrial catheter insertion for hemodialysis in patients with multiple venous access failure. We retrospectively evaluated the charts of 27 patients with multiple venous access failure who had intra-atrial dialysis catheter placement between October 2005 and October 2010 in our clinic. Permanent right atrial dialysis catheters were placed through a right anterior mini-thoracotomy under intratracheal general anesthesia in all patients. Demographics of the cases, the patency rates of hemodialysis via atrial catheterization, existence of any catheter thrombosis, and catheter-related infections were documented and used in statistical analysis. Seventeen women (63%) and 10 men (37%) with the mean age of 59.0 ± 7.1 years (47-71) were enrolled in this study. Chronic renal failure was diagnosed for the mean of 78.9 ± 24.3 months (33-130). Five patients (18.5%) died. Ventricular fibrillation and myocardial infarction were the causes of death in the early postoperative period in two patients. Two of the remaining three patients died because of cerebrovascular events, and one patient died because of an unknown cause. Ten patients (37%) had been using anticoagulate agents (warfarin) because of concomitant disorders such as deep vein thrombosis, operated valve disease, and arrhythmias. Catheter thrombosis and malfunction was determined in three cases (11.1%). Intra-atrial hemodialysis catheterization is a safe and effective life-saving measure for the patients with multiple venous failure and without any possibility of peritoneal dialysis or renal transplantation.     

Aggrecan synthesis and secretion. A paradigm for molecular and cellular coordination of multiglobular protein folding and intracellular trafficking

Each globular domain of exported multiglobular proteins putatively undergoes chaperone surveillance in the endoplasmic reticulum lumen. It is difficult to visualize how surveillance of multiple globular domains might be orchestrated and regulated. Aggrecan core protein has been used as a prototype for this problem by examining transfection of informative constructs into Chinese hamster ovary cells. The salient results are as follows: 1) aggrecan's N-terminal G1 domain is minimally secreted, and its flanking Golgi reporter sites are not decorated with glycsoaminoglycan chains; in contrast, its C-terminal G3 domain is readily secreted with flanking GAG chains, and G3 also facilitates G1 secretion; 2) G3 but not G1 can be intracellularly cross-linked to chaperone Hsp25; 3) G3 and Hsp25 remain noncovalently bound and are secreted together when G3 is situated N-terminal to its normal location; 4) exon 15, which encodes the center of G3's C-lectin subdomain, is necessary and sufficient for G3 secretion. A model is proposed in which Hsp25 piggybacks onto nascent G3 in the cytosol during a translocational pause and enters the ER lumen with G3, and once G3 properly folds, Hsp25 releases G3 and recycles to the nucleus while G3 continues to the Golgi stacks, providing passage for the entire core protein.     

Neonatal purpura fulminans due to homozygous protein C deficiency

All aspects of surgical decision making,--why, what, when, where, how and to whom--are being subjected to an increasingly accurate analysis. The principles of this analysis should form an essential part of the theoretical curriculum of all surgeons, young and old. Only by these means can the production of health benefits be maximized and the definitive goal of all surgical care be attained: the maximization of produced health benefits. This article provides a short outline of decision analysis in surgery.     

On the Importance of Electric Currents Flowing directly into the Mould during an ESR Process

In the present paper a numerical model is developed to predict the exact electric current paths in the slag region of an Electro‐Slag‐Remelting (ESR) process. The model solves the momentum and energy equations. The solidification of the slag at the mould is modelled with an enthalpy‐porosity approach. The magnitude of the Joule heating and the Lorentz force are derived from the computed electric current lines. The localization where the Joule heating occurs controls the temperature distribution. The electric current distribution is in turn influenced by the temperature field through the temperature dependant electric conductivity. With this numerical tool the electric current paths are exactly computed by choosing the less resistive way to the liquid pool, or to the mould. For a given electric intensity the model predicts the power generated by the system and the solidified slag thickness at the mould. The model is validated by comparing its results with experiments on a small scale ESR process with high current density.     

Effects of radiologists' skill and experience on patient doses in interventional examinations

In this study, effects of radiologists' skill and experience on patient doses were investigated. Dose-area product and entrance surface doses of two groups of patients, one examined by a number of junior radiologists and another one by a senior radiologist, have been compared for the diagnostic interventional examinations of cerebral and lower limbs. Collimation of the X-ray beam and shortening the fluoroscopy times by the senior radiologist considerably reduced the patient doses for interventional cerebral examinations.