Searching for the factors which affect self-healing capacitordegradation under non-sinusoidal voltage

The purpose of this paper is to show how voltage distortion may cause accelerated aging of insulation systems, particularly of self-healing capacitors. Distortion is due to the presence, in the supply voltage waveform, of harmonics which are typically detected in distribution ac networks. These harmonics sum up to the fundamental component giving rise to voltage waveforms which can considerably differ, for peak value and shape, from the sinusoidal waveform. The results of life tests carried out on capacitors subjected to non-sinusoidal voltage allow an investigation on the most significant factors which affect endurance to be performed, resorting to appropriate statistical techniques. The peak voltage seems to be the most significant factor for aging acceleration, but also waveshape and RMS voltage play a significant role. A life model is thus derived, which provides a relationship between failure time, defined as the time required to reach a given decrease of capacitance, and appropriate figures derived from the voltage waveform. These figures take into account peak voltage, waveshape and RMS voltage     

Evaluation of Time-Temperature Parameter Effects on the Structural Characteristics of Films Obtained by Aqueous Polymeric Dispersions

Pellet cores, containing d-indobufen as the active principle, were prepared by the extrusion-spheronization process and coated with an aqueous polymeric dispersion using Wurster bottom-spray equipment. The present study investigated factors affecting the film properties, such as the product temperature during the coating process and the effects of the thermal postcoating treatment (curing phase), carried out in different drying conditions. The experimental results, in terms of drug release control, confirm that the properties of the film coating depend on the substrate temperature, which directly influences the coalescence process of the polymeric dispersion. Moreover, along with time and temperature of the drying phase, the type of equipment used affects the performance of the film coating dosage form. In particular, using the fluidized bed at a high temperature for a short time produced a film coating structure that seemed to remain unchanged after storage.     

Dynamic cardiomyoplasty: clinical follow-up at 12 years

OBJECTIVE: The purpose of this study is to evaluate the long-term outcome of dynamic cardiomyoplasty. This surgical technique was conceived to assist the failing heart. The many proposed mechanisms of action of cardiomyoplasty are: (1) systolic assist; (2) limitation of ventricular dilation; (3) reduction of ventricular wall stress (sparing effect); (4) ventricular remodeling with an active girdling effect; (5) angiogenesis; and (6) a neurohumoral effect. METHODS: We investigated 95 patients in our hospital undergoing this procedure due to severe chronic heart failure, refractory to optimal medical treatment. Patients had a mean age of 51 +/- 12 years. The etiology of heart failure was ischemic 55%, idiopathic 34%, ventricular tumor 6%, and other 5%. The mean follow-up was 44 months. RESULTS: The mean New York Heart Association (NYHA) functional class improved postoperatively from 3.2 to 1.8. Average radioisotopic left ventricular (LV) ejection fraction increased from 17 +/- 5 to 27 +/- 4% (P < 0.05). Stroke volume index increased from 32 +/- 7 to 43 +/- 8 ml/beat per m2 (P < 0.05). The heart size remained stable over the long term. Following cardiomyoplasty, the number of hospitalizations due to congestive heart failure was reduced to 0.4 hospitalizations/patient per year (preoperative: 2.5, P < 0.05). Computed tomography scans showed at long term a preserved latissimus dorsi muscle structure in 84% of patients. Survival probability at 7 years is 54%. Six patients underwent heart transplant after cardiomyoplasty (mean delay: 25 months), due to the natural evolution of their underlying heart disease. There were no specific technical difficulties. CONCLUSIONS: Clinically, this procedure reverses heart failure, improves functional class and ameliorates quality of life. The latissimus dorsi muscle histological structure is maintained at long-term, when postoperative electrostimulation is performed, avoiding excessive stimulation. Cardiomyoplasty may delay or prevent the progression of heart failure and the indication of cardiac transplantation.     

Polycyclic aromatic hydrocarbons enhance the production of phorbol 12-myristate 13-acetate-induced superoxide ions in human monocytes

To welcome the transitions in management and leadership roles, a leader may consider developing the skills necessary to promote the success of interdisciplinary point-of-service teams. The author discusses factors that contribute to success in leading a point-of-service team. Key strategies and leader behaviors are addressed. A case study describing one point-of-service team for patient care redesign is presented and analyzed. The experience was viewed very positively by the leaders of the team; opportunities for further improvement are offered.     

Short-term and long-term mechanical characteristics of BSCCO steel-reinforced tapes

An investigation on short-term and long-term mechanical characteristics of Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ reinforced tapes is presented in this paper. Results of critical current measurements obtained after bending, as well as during application of tensile stress and strain, are shown. Data are processed to provide a threshold model for the bending test, according to which bending on large-diameter mandrels does not provide appreciable damage to superconductor tapes. The values of critical current density derived from tensile stress and strain are investigated by the Weibull cumulative function, showing the existence of two distinct failure modes, determined by different strengths of reinforced tapes. This statistical analysis provides a methodology for a feasible quality control test on superconductive tapes. Long-term behavior evaluation, carried out through life lines derived from tests under different levels of stress and strain, indicate that reinforced tapes show largely improved endurance with respect to nonreinforced ones.     

Combined surgery of the mitral valve and the abdominal aorta in a case of Takayasu's disease

The authors report the case of a 34-year-old woman, of North African origin, with mitral valve disease and abdominal aortitis. The differential diagnosis between Takayasu' disease, embolism of cardiac origin and rheumatic aortitis is discussed. Treatment of these lesions was by combined cardiac and vascular surgery in a single-stage operation.     

Role of the laboratory in the diagnosis and treatment of lead poisoning]

In an experimental canine model, topical application of phenylephrine hydrochloride (Neo-Synephrine) to the urethral mucosa was demonstrated to cause a rise of intraurethral pressure which persisted for over 2 h without any rise of arterial pressure. There was no intraurethral pressure change after the topical application of phentolamine (Regitine) or phenoxybenzamine (Dibenzyline). No effect was observed on the intraurethral pressure following isoprenaline (Isuprel) application, but a marked fall in arterial pressure was observed.