An accurate approximation for the highly efficient sampling of polar scattering angle of electron elastic single-scattering events

In single-event Monte Carlo electron transport simulations, elastic scattering events dominate the changes in electron trajectories due to collisions. Classically, the polar scattering angle due to an elastic collision can be sampled efficiently from the screened Rutherford cross section. However, the screened Rutherford cross section fails for both high Z materials and when the incident electron energy becomes too low. Alternatively, improved simulation accuracy for electrons in all energy ranges and through all materials may be obtained by sampling directly from differential data derived from partial-wave-expansion method (PWEM) calculations based on theoretical atomic potential models. While sampling directly from wave calculations will yield simulation results to the best known physical accuracy, it comes at the cost of simulation time. This is due to a sampling process that is typically more involved when compared with using the screened Rutherford cross section. In this work we present a relationship capable of reproducing the moments of the differential cross section derived from PWEM calculations, resulting in good preservation of forward and backscattering peaks. The relationship is directly invertible and is as easily sampled as the Rutherford cross section. Most important, the data presented in this paper in combination with this relationship produce Monte Carlo simulation results which are comparable with those using the exact differential cross section from PWEM calculations for elements Z = 1 to 96 and for incident electron energies from 300,000 down to 50 eV.     

Nafion‐115/aromatic poly(etherimide) with isopropylidene groups/imidazole membranes for polymer fuel cells

Proton exchange membrane fuel cells (PEMFCs) with Pt/C gas diffusion electrodes and graphite single‐serpentine monopolar plates were constructed based on an aromatic poly(etherimide) with isopropylidene groups (PI)/imidazole (Im) and a popular Nafion‐115 matrix. The electrochemical properties of PEMFCs were tested at 25 and 60°C. The maximum power density of 171 mW/cm² and the maximum current density of 484 mA/cm² were detected for Nafion‐115/PI membrane. For both constructed PEMFCs the efficiency at 0.6 V was found about 41%. Immersion of Nafion‐115 in PI or PI/Im increased the thermal stability and mechanical properties of membranes. Thermal, mechanical properties and morphology of membranes were characterized by TGA, and AFM techniques including force spectroscopy. Interactions between the components in composite membranes were established by FT‐IR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42436.     

Influence of aluminium electrode preparation on PCE values of polymeric solar cells based on P3HT and PCBM

The main goal of the paper was investigation of influence of aluminum electrode preparation via thermal evaporation (TE) and the magnetron sputtering (MS) on power conversion efficiency (PCE) of polymeric solar cells. The photovoltaic properties of such three kinds devices based on poly(3-hexylthiophene-2,5-diyl) (P3HT) as ITO/P3HT/Al, ITO/P3HT:PCBM (1:1, w/w)/Al and ITO/PEDOT:PSS/P3HT:PCBM (1:1, w/w)/Al were investigated. For the constructed devices impedance spectroscopy were analyzed. For devices lack of PEDOT:PSS layer or lack of PCBM, photovoltaic parameters were very low and similar to the parameters obtained for device with Al electrode prepared by magnetron sputtering. The devices comprising PEDOT:PSS with P3HT:PCBM showed the best photovoltaic parameters such as a V_OC of 0.60 V, J_SC of 4.61 mA/cm², FF of 0.21, and PCE of 5.7 × 10^?1%.     

Aliphatic–aromatic poly(azomethine)s with ester groups as thermotropic materials for opto(electronic) applications

We have explored the opto(electronic) and liquid crystal properties of a new series of semiconducting materials based on aliphatic–aromatic poly(azomethine)s. The structures of polymers were characterized by means of FTIR, ¹H, ¹³C NMR spectroscopy, and elemental analysis. UV–vis properties of the thin films of the polymers were investigated on the quartz substrate. The lowest optical energy gap (E_g) at 2.28 eV was found. The polymers were irradiated with a test dose of 2 Gy Co-60 gamma-rays to detect their thermoluminescence properties in the temperature range 25–200 °C. Mesomorphic behavior was investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) studies. Being into consideration backbone geometry, all polymers, excepted polymer PAZ2, obtained from poly(1,4-butanediol)bis(4-aminobenzoate) and 9-(2-ethylhexyl)carbazole-3,6-dicarboxaldehyde, exhibited liquid-crystalline properties. Moreover, the electrical characterizations of bulk heterojunction (BHJ) and bilayer devices with the following architecture ITO/PEDOT/PAZ:TiO₂/Al were investigated. Additionally, devices without and with TiO₂ layer such as ITO/PAZ/Al and ITO/TiO₂/PAZ/Al were prepared and investigation in the dark and during irradiation with light (under illumination 1000 W/m²). The sol–gel technique was applied to prepared TiO₂ layers and powders. Moreover, impedance spectroscopy at different temperatures for electrical properties measurement was used. Additionally, the compounds were tested using various AFM techniques such as Mode and Phase Imaging and local contrast force–distance curve measurement and roughness (Ra, Rms) along with skew and kurtosis are presented.     

A new computational approach for the linearized scalar potential formulation of the magnetostatic field problem

We consider the linearized scalar potential formulation of the magnetostatic field problem in this paper. Our approach involves a reformulation of the continuous problem as a parametric boundary problem. By the introduction of a spherical interface and the use of spherical harmonics, the infinite boundary condition can also be satisfied in the parametric framework. The reformulated problem is discretized by finite element techniques and a discrete parametric problem is solved by conjugate gradient iteration. This approach decouples the problem in that only standard Neumann type elliptic finite element systems on separate bounded domains need be solved. The boundary conditions at infinity and the interface conditions are satisfied during the boundary parametric iteration.     

Fabrication and evaluation of Ni-GDC composite anode prepared by aqueous-based tape casting method for low-temperature solid oxide fuel cell

Large-size, 8 cm × 8 cm, NiO-Gd_0.1Ce_0.9O_1.95 (Ni-GDC) composite anodes have been successfully fabricated by aqueous-based tape casting method for anode-supported solid oxide fuel cell (SOFC). The pre-sintered anode green tape was coated with a GDC electrolyte film by spray coating method and then co-sintered together to obtain electrolyte/anode bi-layer. The cathode, which is made of La_0.8Sr_0.2Co_0.2Fe_0.8O₃-GDC (LSCF-GDC) was screen printed onto the electrolyte film and sintered to form a complete anode-supported SOFC. The performance of the cell was evaluated on an in-house developed test station between 500 and 650 °C. Due to the limitation of the test station for large-cell testing, small-size samples with dimensions of 2.5 cm × 2.5 cm were cut out from the large-cell. For the single cell with humidified hydrogen as fuel and air as oxidant, the maximum power density achieved 909, 623, 335 and 168 mW cm⁻² at 650, 600, 550 and 500 °C, respectively. Impedance analysis confirmed that the performance of single cells below 600 °C was retarded primarily due to the slow interfacial reaction kinetics at reduced temperatures. Development of catalytically active electrode materials, especially the cathode material and improvement of the electrode microstructure are thus crucial for achieving a high performance low-temperature SOFC.     

A promising Ni–Fe bimetallic anode for intermediate-temperature SOFC based on Gd-doped ceria electrolyte

Anode supported solid oxide fuel cells (SOFC) based on Ni–Fe bimetal and gadolinia-doped ceria (GDC) composite anode were fabricated and evaluated in the intermediate- and low-temperature range. Ni_0.75Fe_0.25-GDC anode substrate and GDC electrolyte bilayer were prepared by the multi-layered aqueous tape casting method. The single cell performance was characterized with La_0.6Sr_0.4Co_0.2Fe_0.8O₃-GDC (LSCF-GDC) composite cathode. The maximum power density reached 330, 567, 835 and 1333 mW cm⁻² at 500, 550, 600 and 650 °C, respectively. Good long-term performance stability has been achieved at 600 °C for up to 100 h. The improved single cell performance was achieved in the reduced temperature after the long-term stability test. The maximum power density registered 185 and 293 mW cm⁻² at 400 and 450 °C, respectively. The impedance spectra fitting results of the test cell revealed that the improved cell performance was attributed to the much lower electrochemical reaction resistance. XRD and SEM examination indicated that the outstanding performance of the single cell seemed to arise from the optimized composition and excellent microstructure of Ni_0.75Fe_0.25-GDC anode, as well as the improved stability of the anode microstructure with prolonged testing time.     

Urinary nuclear matrix protein as a marker for transitional cell carcinoma of the urinary tract

PURPOSE: The purpose of this trial was to evaluate an immunoassay for urinary nuclear matrix protein, NMP22, as an indicator for transitional cell carcinoma of the urinary tract. MATERIALS AND METHODS: Three groups of subjects participated in this trial of NMP22: 1-175 with transitional cell carcinoma, 2-117 with benign urinary tract conditions and 3-375 healthy volunteers. Each subject provided a single (3 voids) urine sample for analysis at the time of study entry. Each sample was assayed for the level of NMP22. RESULTS: In normal healthy volunteers and in subjects with benign conditions median NMP22 levels were 2.9 and 3.3 units per ml., respectively. Median urinary NMP22 levels in patients with transitional cell carcinoma were significantly greater than in comparison subjects. Patients with active transitional cell carcinoma had significantly greater median urinary NMP22 levels than those with no evidence of disease (6.04 versus 4.11 units per ml., p = 0.027, 1-tailed Mann-Whitney U test). We noted no effect of tumor grade, extent of disease or exposure to intravesical therapy on urinary NMP22 levels. CONCLUSIONS: NMP22 is a promising urinary tumor marker for monitoring transitional cell carcinoma. Nuclear matrix proteins are a new class of tumor markers that represent the basis for the development of assays with increased efficacy for the detection and treatment of cancer.     

Evolution of microstructure and local thermal conditions during directional solidification of A356-SiC particle composites

Solidification microstructures of aluminium silicon alloy (A-356) containing 0, 10, 15 and 20 vol % silicon carbide particles formed during directional solidification from a chill have been studied and compared with the structures obtained during solidification of the base alloy under similar mould and chill conditions. Columnar dendritic structure was observed during solidification of the base alloy at all distances from the chill. In the case of composites, the presence of silicon carbide particles disturbs the orderly aligned arrangement of dendrites observed in the base alloy, under similar solidification conditions, except near the chill surface where a particle-free zone is observed due to probable pushing of particles by the macroscopic solidification front with cell spacings finer than the particle size. During the entire range of solidification conditions studied in this work, the silicon carbide particles are pushed by growing dendrites of -aluminium into the last freezing eutectic liquid. The observations on pushing of silicon carbide particles have been examined in relation to existing models on particle pushing by planar solidification fronts. Even in the regions away from the chill, where silicon carbide particles are present, there are large regions covering several dendrite arm spacings where there are no particles representing another form of macrosegregation of particles. It is observed that the secondary dendrite arm spacings (DAS)of -aluminium are related to cooling rate by an equation DAS =b (T) ⁿ for the base alloy as well as for the composite. The coefficientb is generally higher for composites than for base alloy, and it is found to be a function of particle content. The value ofn for the composite is close to the value of the base alloy and is not significantly influenced by the presence of particles. Cooling rate, temperature gradients and the rate of advancement of the solidification front have been experimentally measured for the base alloy as well as for the composites during unidirectional solidification. The study indicates that the presence of particles themselves alters the cooling rates, temperature gradients and growth rate of the macroscopic solidification front under identical thermal surroundings during solidification. The possible influences of these alterations in growth condition on the solidification microstructure due to the presence of particles are discussed together with the other possible direct influences of particles on dendritic growth of aluminium-silicon alloys.     

Hybrid polymer electrolyte membrane fuel cell–lithium‐ion battery powertrain testing platform – hybrid fuel cell electric vehicle emulator

A testing and validation platform for hybrid fuel cell (FC)–lithium‐ion battery (LIB) powertrain systems is investigated. The hybrid FC electric vehicle emulator enables testing of hybrid system components and complete hybrid power modules up to 25 kW for application in electric light‐duty vehicles, light electric vehicles and so forth. A hybrid system comprising a 10‐kW_el low‐temperature polymer electrolyte membrane FC stack and an 11.5‐kWh LIB pack is installed. The system supplies power to a 20‐kW permanent magnet synchronous motor and a 25‐kW alternating current asynchronous, electrically programmable dynamometer is used to simulate the vehicle load during testing at dynamic drive cycle. The steady‐state performance tests of the direct current (DC) motor, DC/DC converter, low‐temperature polymer electrolyte membrane FC stack and LIB are performed as well as dynamic tests of the complete hybrid system. The Economic Commission for Europe driving cycle is selected as a reference cycle to validate the investigated hybrid FC–LIB powertrain. An efficiency of 83% and 95% is measured for electric motor and DC/DC converter, respectively. An average stack efficiency of 50% is achieved. An average hydrogen consumption of 3.9 g * km^?1 is reached during the Economic Commission for Europe driving cycle test. Copyright © 2017 John Wiley & Sons, Ltd.