Solar test of an integrated sodium reflux heat pipe receiver/reactor for thermochemical energy transport

A chemical reactor for carbon dioxide reforming of methane was integrated into a sodium reflux heat pipe receiver and tested in the solar furnace of the Weizmann Institute of Science, Rehovot, Israel. The receiver/reactor was a heat pipe with seven tubes inside an evacuated metal box containing sodium. The catalyst, 0.5 wt% Rh on alumina, filled two of the tubes with the front surface of the box serving as the solar absorber. In operation, concentrated sunlight heated the front plate and vaporized sodium from a wire mesh wick attached to the other side. Sodium vapor condensed on the reactor tubes, releasing latent heat and returning to the wick by gravity. The receiver system performed satisfactorily in many tests under varying flow conditions. The maximum power absorbed was 7.5 kW at temperatures above 800°C. The feasibility of operating a heat pipe receiver/reactor under solar conditions was proven, and the advantages of reflux devices confirmed.     

A comparative study of human immunodeficiency virus culture, polymerase chain reaction and anti-human immunodeficiency virus immunoglobulin A antibody detection in the diagnosis during early infancy of vertically acquired human immunodeficiency virus infection

Asynchrony of delivered and spontaneous breaths in mechanically ventilated infants may impair gas exchange and prolong the need for assisted ventilation. We conducted a randomized, controlled trial of a patient-triggered, flow-synchronized ventilator on 30 preterm infants with respiratory distress syndrome who weighed between 1100 and 1500 gm at birth. Entry criteria included radiographic evidence of respiratory distress syndrome and the need for mechanical ventilation and surfactant replacement therapy. Patients were assigned to either conventional time-cycled, pressure-limited ventilation or patient-triggered, flow-synchronized ventilation in an assist/control mode. Otherwise clinical management was identical. Time to extubation was the primary outcome measure. Patients treated with flow-synchronized ventilation were weaned more rapidly and had a significantly shorter mean time to extubation than those treated with time-cycled, pressure-limited ventilation, 119 versus 271 hours, p = 0.0152. In addition, there was no difference in the rate of complications between the two groups. There were, however, considerable reductions in patient charges of $4344 per patient in the flow-synchronized ventilation group.     

Methanation of synthesis gas in a solar chemical heat pipe

The reversible reaction CH₄ + CO₂ = 2H₂ + 2CO is under investigation as a chemical heat pipe for storage and transport of solar energy. In this paper, the study of the back exothermic reaction, the methanation of CO-rich synthesis gas, is reported. Three different methanators were constructed and operated in a closed-loop, with the reforming products from the reaction carried out in the solar furnace. The best performance was obtained with a six-stage adiabatic methanator. The experimental results are compared with computer calculations, assuming equilibrium at each stage. The agreement between experimental and calculated results is satisfactory. Scale-up work on a 400 kW unit is in progress.     

Craniofacial computer-assisted surgical planning and simulation

Computer-assisted planning and simulation of craniofacial surgery has progressed from development, through validation, and into clinical use. CT scans are transferred from the radiology department to a graphics workstation in the surgeon's office or laboratory, where data postprocessing and visualization for anatomic evaluation and surgical simulation are performed. Quantitative and qualitative comparative analyses between the plan/simulation and the actual postoperative result provide the feedback that validates or refutes the preoperative assessment and simulated intervention. The optimum surgical solution can be chosen from many possibilities. Interactive computer-assisted surgical simulation is also useful for morbidity-free training of inexperienced surgeons.     

Absorption, tissue distribution, and excretion of zinc acexamate in rats

AIM: The SRK II formula has been widely used for intraocular lens (IOL) power calculations. The predictability of this formula is evaluated in axial myopic patients. METHODS: Planned extracapsular cataract extraction and posterior chamber IOL implantation (PECCE + IOL) were performed on 98 eyes of 98 patients with axial length > 24.5 mm. Cases had no preoperative complications and postoperative visual acuity was at least 0.5 (Snellen). Corneal refractive power and axial length were measured preoperatively and emmetropic IOL power calculations were made using the SRK II formula. Long-term (mean 4.7 months) visual acuities and refractions were noted postoperatively. RESULTS: The absolute refractive error was < 1.00 Diopters (D) in 57 eyes (58.2%) and < 2.00 D in 83 eyes (84.7%). The mean absolute error of the SRK II formula in axial myopia was 1.16 D +/- 0.78 SD. CONCLUSIONS: The SRK II formula is not very accurate in axial myopic patients.     

Acute and delayed effects of prolonged exercise on serum lipoproteins. II. Concentration and composition of low-density lipoprotein subfractions and very low-density lipoproteins

To investigate the effects of a single period of prolonged exercise on lipoprotein concentration and composition, 13 healthy endurance-trained men were examined before and after (1 h, 20 h) a cross-country run [30 km, time: 130 (SD 7.4) min]. The data show that following acute exercise, serum triglyceride (TG) concentration were reduced (36%) as a consequence of a reduced number (31%) of very low density lipoprotein (VLDL) particles. Changes in composition of VLDL were present but less evident. In contrast to this, acute exercise did not induce significant changes in the average concentration of individual low-density lipoprotein (LDL) subfractions. However, changes in dense LDL [density (d) > 1.044 g.ml-1] concentration were significantly correlated to changes in serum TG: a reduction of dense LDL occurred in subjects with large reductions in serum TG. In addition, LDL composition changed significantly. Immediately (1 h) after exercise the TG content of all LDL subfractions was reduced. These reductions were significant in large (d = 1.006-1.037 g.ml-1) and small LDL (1.044-1.063 g.ml-1). It can be concluded therefore from our study that acute exercise primarily altered the composition of LDL subfractions while their concentration remained stable.     

Imaging of laryngeal cancer

CT and MRI are the main modalities for examination of laryngeal pathology. Generally, MRI seems to be the optimal method of examination in cooperative patients, especially for evaluation of their larynx before an attempted partial laryngectomy. The choice between the two modalities will also be determined by one's experience with these modalities. The possibilities of CT and MRI vary clearly from each other regarding detection of cartilage invasion. MRI seems to be more sensitive than CT in detection of neoplastic cartilage invasion, but seems to have a somewhat lower specificity, especially for thyroid cartilage involvement. There are increasing indications for imaging regarding tumor volume, and signs of cartilage involvement may have prognostic significance for the risk of tumor recurrence.