Magnetotransport and magnetic properties of InAs/Mn digital alloys

We have investigated the magnetic and magneto-transport properties of a systematic sequence of five InAs/Mn digital alloys grown by a combination of molecular beam epitaxy and atomic layer epitaxy. The samples consist of 30 periods of Mn fractional monolayers (ML) (0.17–0.5 ML) separated by 14 ML thick InAs spacer layers in a superlattice configuration. Four samples show n-type electrical conduction while the fifth (0.25 ML Mn) is p-type. Squid magnetization measurements performed on these samples show remnant magnetization above room temperature, which is apparently related to a second phase.     

Evaluation of Zn and Fe in diets of patients with chronic renal failure

Having in mind the importance of Fe and Zn content in the diets of nondialyzed patients with chronic renal failure, diets of 39 patients with ages varying from 18 to 79 years under a conservative treatment were analyzed by INAA. The 24-hour recall method was used for sample collection. The content of proximate composition was also determined. The average daily dietary intake was compared to the new recommended values by the Food and Nutrition Board. It was observed that the diets were deficient for these elements and, therefore, there should be a nutritional follow-up to avoid possible negative effects. This revised version was published online in August 2006 with corrections to the Cover Date.     

Solving Sequences of Refined Multistage Stochastic Linear Programs

Multistage stochastic programs with continuous underlying distributions involve the obstacle of high-dimensional integrals where the integrands' values again are given by solutions of stochastic programs. A common solution technique consists of discretizing the support of the original distributions leading to scenario trees and corresponding LPs which are – up to a certain size – easy to solve. In order to improve the accuracy of approximation, successive refinements of the support result in rapidly expanding scenario trees and associated LPs. Hence, the solvability of the multistage stochastic program is limited by the numerical solvability of sequences of such expanding LPs. This work describes an algorithmic technique for solving the large-scale LP of refinement ν based on the solutions at the previous ν?1 refinements. Numerical results are presented for practical problem statements within financial applications demonstrating significant speedup (depending on the size of the LP instances).     

Fullerene C6 0 Aggregates in Polymethyl Methacrylate Films

The structure of aggregates of fullerene C_{6 0} introduced into films of radical polymethyl methacrylate in the stage of solution preparation was studied by wide-angle X-ray diffraction.     

Quasioptical Approach for Meniscus Lens Corrected Horn: Application to Cassegrain Systems

The Beam Mode Expansion (BME) approach for corrugated conical feed horn plus meniscus lens is presented. This approach is useful for providing the radiation pattern as it propagates through an optical system. A developed theoretical model has been verified measuring near and far field of a built horn and lens. These results have been used for designing the optical system of a Cassegrain antenna at 100GHz using the fundamental Gaussian beam mode (GBM) of the new approach. Multimode analysis has been performed with the pre-designed system in order to test the fundamental GBM results.     

Simultaneous determination of trace cadmium and mercury in Chinese herbal medicine by non-dispersive atomic fluorescence spectrometry using intermittent flow vapor generator.

A method was proposed for the simultaneous determination of trace cadmium and mercury by vapor generation non-dispersive atomic fluorescence spectrometry using an intermittent flow system. The effects of the parameters on the performance were studied systematically. The parameters such as acid concentration of the reaction medium, flow rate of the carrier gas and shield gas, the observation height and the atomizer temperature, etc. which affected the sensitivity, were optimized. Ascorbic acid, cobalt ion and thiourea were used as enhancement reagents or masking agents to enhance the generation efficiency of the volatile species of Cd and Hg. The mechanisms of their effects on vapor generation were investigated. In the presence of thiourea and ascorbic acid, the influences of some coexisting elements on the determination of cadmium and mercury were investigated. The detection limits (3sigma) were 0.010 microg l(-1) for Cd and 0.019 microg l(-1) for Hg, respectively. The relative standard deviations for Cd and Hg at 1.00 microg l(-1) were 2.6% and 0.97% (n = 11), respectively. The proposed method has been satisfactorily applied to the determination of trace cadmium and mercury in Chinese herbal medicine.     

Fatigue Loading and Life Prediction in Three Fretting Fatigue Fixtures

Three fixtures for conducting laboratory fretting fatigue tests are described and their respective testing methods and the results of the analysis are compared. Each of these fixtures has been used to investigate the effects of various parameters of interest in fretting fatigue. These fixtures include a unique apparatus in which all load applied to the specimen is transferred to the fretting pads, an apparatus similar to many found in the literature where partial load transfer occurs across the pads, and a simplified dovetail fixture in which the clamping load, P, and the shear load, Q, are varied in phase. Select test conditions from prior experiments performed on identical material and resulting in similar lives ranging from one to ten million cycles from these fixtures are identified. The various testing conditions were used to compute the unique stress field for each case. The resulting contact stresses were used to calculate crack initiation based criteria, and to calculate stress intensity factors. The three fixtures were shown to be able to accommodate a range of loads, fretting pad contours, and specimen geometries that produced a variety of stress fields. A crack-initiation-based criterion was shown to predict the failure lives of thinner specimens accurately. The stress intensity factor calculations showed the possibility of a crack arresting for a stress field that decays rapidly and the possibility of a local minimum for K as a function of depth. The fixtures are shown to be complementary in generating data for development of robust fretting fatigue models that use these criteria.     

Interactions of Eu3+ and Am3+ with humic acid extracted from soil of Yongkwang in the Okchon Basin of the Korean Peninsula

Summary The stability constants of Eu³⁺ and Am³⁺ with the site specific humic acid (YKHA) have been determined. The humic acid has been extracted from the soil of Yongkwang area belonging geologically to the Okchon Basin of the Korean Peninsula, where the nuclear power plant is located. The total carboxylate capacity, the acidity constant (pKa), and the binding constants with Eu³⁺ and Am³⁺ have been determined for humic acid.