Improvement of Makrofol® De 7-2 polycarbonate optical properties by thermal annealing for the registration of alpha particles

AbstractTranslucent Makrofol® DE 7-2 polycarbonate samples are thermally-annealed at 200°C for different durations in the air. UV–Vis spectra of the thermally-annealed Makrofol® DE 7-2 were measured. The results reveal that the light absorbance by thermally-annealed Makrofol® DE 7-2 is significantly minimized which enhances the visualization of the charged particle track registered on it. Both direct and indirect band gaps show pronounced stability over all thermal annealing durations; the same behavior was observed to Urbach’s energy and the number of carbon atoms per cluster where no reasonable alteration was observed. The thermally-annealed Makrofol® DE 7-2 was irradiated with 3MeV alpha particles and etched for different durations in 75% 6N KOH+25% C2H5OH at 50°C. Alpha particle track diameter is found to be linearly correlated with the etching time up to 3h before the Bragg peak. The chemical etching efficiency of alpha particle tracks ranges from 0.22 to 0.26. The current new findings indicate the possibility to improve the optical properties of translucent Makrofol® DE 7-2 by a thermal annealing for its utilization in charged particle registration

Modified Koyanagi Technique in Management of Proximal Hypospadias

Background/Purpose: One stage urethroplasty with parameatal foreskin flap (OUPF) applicable to all types of hypospadias was first described by Tomohiko Koyanagi, however high complication rates were reported.The aim of this study is to analyze the results of a modification of the Koyanagi technique as a one-stage repair of proximal hypospadias. Patients and Methods: During the period of from March 2008 to March 2009, 30 patients underwent treatment of proximal hypospadias using the modified Koyanagi technique. Patient age at the time of surgery ranged from 6 to 24 months. In all cases, the urethral opening was at or just proximal to the penoscrotal junction. Follow up ranged from 3 months to 1 year. Results: Primary success occurred in 27 cases (90%) with accepted cosmetic appearance. Complications occurred in 3 cases (10%). Urethrocutaneous fistula occurred in 2 cases (6.7%). Meatal recession occurred in 1 case (3.3%). There was no incidence of meatal stenosis, urethral stricture, residual chordee or complete flap necrosis. Conclusion: The modified technique permits one-stage repair of proximal hypospadias with low complication rates. Keywords: Hypospadias, Koyanagi, One stage urethroplasty

Rigorous Characterization of Carbon Nanotube Complex Permittivity over a Broadband of RF Frequencies

This work presents a comprehensive characterization of the frequency dependence of the effective complex permittivity of bundled carbon nanotubes considering different densities over a broadband of frequencies from 10 MHz to 50 GHz using only one measurement setup. The extraction technique is based on rigorous modeling of coaxial and circular discontinuities using mode matching technique in conjunction with inverse optimization method to map the simulated scattering parameters to those measured by vector network analyzer. The dramatic values of complex permittivity obtained at low frequencies are physically explained by the percolation theory. The effective permittivity of a mixture of nano-particles of alumina and carbon nanotubes versus frequency and packing density is studied to verify the previously obtained phenomenon

Near-total pancreatectomy for persistent hyperinsulinemic hypoglycemia of infancy (nesidioblastosis): Mansoura experience

Background/purpose Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is the most common cause of persistent hypoglycemia in infancy with consequences such as seizures and brain damage. Treatment that prevents the occurrence of these sequele is essential. When medical therapy fails or complications are anticipated, early pancreatectomy is recommended to maintain euglycemia. The aim of this study was short-term evaluation of near-total pancreatectomy for PHHI after failure of medical treatment in patients in Mansoura, Egypt.Patients and methods During May 2002 to May 2010, 33 patients suffering from persistent hyperinsulinemic hypoglycemia were admitted to Mansoura university child hospital. Twenty patients responded to medical treatment and 13 patients (eight girls and five boys) were treated by near-total (90–95%) pancreatectomy after failure of medical treatment. Their ages at the time of surgery ranged from 20 days to 27 months. Only patients who were surgically managed were included in this study. All of them suffered from symptoms of PHHI: thermoregulatory problems in five cases, tremors in five cases, seizures in three, irritability in five, respiratory distress in eight, apnea in four, hypotonia in four, lethargy in five, and feeding difficulty in four cases. All cases were diagnosed following strict criteria that included bouts of hypoglycemia without acidosis coinciding with increased insulin level. Follow-up ranged from 3 months to 8 years.Results Primary success occurred in two cases (15%); four more cases (31%) developed temporary diabetes mellitus, and one case (8%) had a temporary pancreatic fistula. Eventually, total cure occurred in seven cases (54%); six cases (46%) developed a variety of complications; and persistent hypoglycemia was seen in two. Persistent diabetes mellitus was observed in three patients, developmental delay in one, and persistent neurological deficit in two patients; there was one case of mortality.Conclusion Near-total (90–95%) pancreatectomy is a suitable procedure for treatment of nesidioblastosis not responding to medical treatment and should be performed as early as possible. Keywords: Mansoura, near-total pancreatectomy, persistent hyperinsulinemic hypoglycemi

Analysis of Fuel Burnup and Transmutations at High Burnup of Sodium Fast Breeder Reactor

In this paper, the Monte Carlo N-Particle extended  computer code (MCNP) were used to design a model of the European Sodium-cooled Fast Reactor. The multiplication factor, conversion factor, delayed neutrons fraction, doppler constant, control rod worth, sodium void worth, masses for major heavy nuclei, radial and axial power distribution at high burnup are studied. The results show that the reactor breeds fissile isotopes with a conversion ratio of 0.994 at fuel burnup 70 (GWd/T), and minor actinides are buildup inside the reactor core. The study aims to check the efficiency of the model on the calculation of the neutronic parameters of the core at high burnup

Engineered Carbon-Nanotubes Based Composite Material for RF Applications

Electrical properties of nano-composite materials are extracted to investigate the possibility to engineer novel material for microwave applications. A measurement setup is developed to characterize material in a powder form. The developed measurement technique is applied on nano-particles of alumina, carbon nanotubes (CNTs), and composite mixture of carbon nanotubes and alumina. The effect of packing density on dielectric constant and loss tangent is thoroughly characterized experimentally. The obtained results show that the real part of effective permittivity may be considerably enhanced by increasing the percentage of conducting nano-particles. In addition, it is possible to decrease the loss in a material by mixing low-loss dielectric nano-particles powder in a lossy material

Modeling and Optimization of Microwave Devices and Circuits Using Genetic Algorithms

Abstract-This paper presents a new approach for the simulation and optimization of microwave devices using a genetic algorithm (GA). The proposed technique solves the equations that describe the semiconductor transport physics in conjunction with Poisson's equation, employing an adaptive real-coded GA. An objective function is formulated, and most of the GA parameters are recommended to change during the simulation. In addition, different methods for describing the way the GA parameters change are developed and studied. The effect of GA parameters including the mutation value, number of crossover points, selection criteria, size of population, and probability of mutation is analyzed. The technique is validated by simulating a submicrometer field-effect transistor, and then compared to successive over relaxation, showing the same degree of accuracy along with a moderate speed of convergence. The purpose of this paper is to introduce a new vision for a GA capable of optimizing real value functions with a considerably large number of variables. This paper also represents a fundamental step toward applying GAs to Maxwell's equations in conjunction with the hydrodynamic model, aiming to develop an optimized and unconditionally stable global-modeling simulator