Circuit and EM modeling of wideband high power VHF/UHF combiners

Design of wideband high power VHF/UHF combiners requires developing accurate equivalent circuit models. These high power combining structures generally use nonplanar lines and ferrite cores to enhance their power handling capabilities. For optimum and accurate design, part of these equivalent models should be based on full wave EM analysis. In this article, we present such detailed analysis and give examples for wideband isolating and nonisolating power combiners, along with a novel flux canceling circuitry that has been developed to potentially improve the intermodulation distortion performance of these power combiners. Good agreement between measured and simulated results has been successfully demonstrated for both designs with over 30–450 MHz bandwidth and less than half decibel insertion loss. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

The Norwegian banks in the Nordic consortia: a case of international strategic alliances in banking

Despite the scholarly interest in joint ventures and strategicalliances, the consortium bank movement represents and under-researchedphase in postwar banking history. From 1964 to the early 1980s,many of the largest banks in the world, including the Nordicbanks, entered into international strategic alliances. Almostall of these alliances are now defunct and thus we are lookingat the growth and demise of an organizational form. We followthe Norwegian banks in the Nordic consortia and find that domesticrivals do not cooperate but international rivals do. Legal prohibitionsin the Nordic countries on entry by foreign banks underpinnedthe cooperation. The cooperation broke down when, as a resultof deregulation, the Nordic banks could establish operationsin each other's domestic markets and when domestic mergers disruptedexisting international alliances.     

Fabrication of nanostructured titania on flexible substrate by electrochemical anodization

Titanium films were deposited on ITO (indium tin oxide)-coated PEN (polyethylene naphthalate) and flexible clay substrates by ion beam sputter deposition method. The surface morphology of the deposited films was smooth on PEN and rough on clay substrates. The titanium film deposited on Clay-mo (98% montmorillonite) substrate was anodized in ethylene glycol + 2 vol% H₂O + 0.3 wt% NH₄F solution, and the titanium films deposited on Clay-st (99% stevensite) substrate was anodized in 2-propanol + 16 vol% H₂O + 0.14 M NH₄F solution. Then nanohole-structured titania (TiO₂) films were firstly and successfully fabricated on the flexible transparent clay substrates. The nanohole structures of TiO₂ on both clay substrates were similar to those on PEN and glass substrates. The TiO₂ nanohole structure was almost maintained after annealing at 450 °C for 4 h in air. The optical transmittance of the nanohole-structured TiO₂ films on Clay-st increased from 26% to 54% at 800 nm in wavelength after annealing at 450 °C for 1 h in air.     

Atomic structure of collision cascades in ion-implanted silicon and channeling effects

We have investigated the atomic structures of collision cascades in Bi⁺-implanted silicon. The formation of subcascades or bunching of the primary cascades is clearly observed. The central regions of the cascades were found to be amorphous with a high density of disorder in the surrounding regions. The experimental results are discussed in terms of the computer simulation of the deposited damage energy profiles. The effect of channeling on the deposited damage energy profile is examined. The peak and integrated damage energies are considerably lower in channeling directions compared to random directions.     

Pantoprazole Attenuates MAPK (ERK1/2, JNK,p38)–NF-κB and Apoptosis Signaling Pathways after Renal Ischemia/Reperfusion Injury in Rats

Ischemia/reperfusion injury (IRI) in the kidney is the most common cause of acute renal dysfunction through different cell damage mechanisms. This study aimed to investigate, on molecular basics for the first time, the effect of pantoprazole on renal IRI in rats. Different biochemical parameters and oxidative stress markers were assessed. ELISA was used to estimate proinflammatory cytokines. qRT-PCR and western blot were used to investigate the gene and protein expression. Renal histopathological examination was also performed. IRI resulted in tissue damage, elevation of serum levels of creatinine, urea nitrogen, malondialdehyde, TNF-α, IL-6, IL-1β, up-regulation of NF-κB, JNK1/2, ERK1/2, p38, and cleaved caspase-3 proteins. Furthermore, it up-regulated the expression of the Bax gene and down-regulated the expression of the Bcl-2 gene. Treatment of the injured rats with pantoprazole, either single dose or multiple doses, significantly alleviated IRI-induced biochemical and histopathological changes, attenuated the levels of proinflammatory cytokines, down-regulated the expression of NF-κB, JNK1/2, ERK1/2, p38, and cleaved caspase-3 proteins, and the Bax gene, and up-regulated Bcl-2 gene expression. Moreover, treatment with pantoprazole multiple doses has an ameliorative effect that is greater than pantoprazole single-dose. In conclusion, pantoprazole diminished renal IRI via suppression of apoptosis, attenuation of the pro-inflammatory cytokines’ levels, and inhibition of the intracellular signaling pathway MAPK (ERK1/2, JNK, p38)–NF-κB.     

Total suspended particles and solar radiation over Cairo and Aswan

Measurements were carried out at Cairo (30.05°N, 31.17°E) and Aswan (23.58°N, 32.47°E) in Egypt for three years (1990–1992) by the Egyptian Meteorological Authority. The measurements were done using an Eppley ultraviolet radiometer to measure the global ultraviolet solar radiation (UV), Eppley pyranometers to measure the global solar radiation (G) and the pyrgeometers with silicon dome from Eppley to measure the atmospheric infrared radiation (IR). The clearness index (K_t) and the diffuse fraction (K_d) for both regions have been calculated. Finally the total suspended particles for Cairo and Helwan and their interaction with the solar radiation has been found.     

Effect of preparation parameters on the properties of TiO2 nanoparticles for dye sensitized solar cells

Nano-sized TiO₂ powders have been prepared by sol–gel method. Influences of the different preparation parameters on the TiO₂ nano-powder properties were investigated. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO₂ nanoparticles. Yield efficiency of the resulted nanoparticles was calculated and the reaction efficiency was estimated. Maximum efficiency of 98.9% was achieved at autoclaving temperature of 245 °C for time duration of 12 h. X-ray diffraction analyses show the presence of anatase structure at low and high autoclaving temperatures. Fraction of rutile phase is detected with increasing the calcination temperature and reach 40% at 850 °C. High resolution transmission electron microscopy (HRTEM) showed spherical nanoparticles of 8–9 nm at autoclaving temperature of 130 °C, while elongated nanoparticles of 14–18 nm in length and 9 nm in width were measured at autoclaving temperature of 245 °C. The solar cell performance was measured for various TiO₂ dye sensitized solar cells. Samples of high autoclaving temperature gave an improvement in the efficiency to be 8.5% while those of lower autoclaving temperature had an efficiency of 7.29%. An enhancement in both open circuit voltage (V_oc) and fill factor (FF) is obviously detected, where elongated nanoparticles are measured by HRTEM, which improved the electronic conductivity and consequently FF and V_oc.