Structural and Mechanical Properties of Al/B4C Composites Fabricated by Wet Attrition Milling and Hot Extrusion

In this study,Al matrix composites reinforced by 7.5 and 15 vol.%B₄C particles and also monolithic Al（Al without the B₄C particles） were produced by wet attrition milling and subsequent hot forward extrusion processes.The microstructure of the composites,evaluated by scanning electron microscopy（SEM）,showed that the B₄C particles were properly distributed in the Al matrix.Mechanical properties of the AI/B₄C composites and monolithic Al were investigated by tensile,wear and hardness tests.The results revealed that with increasing content of B₄C particles,the tensile strength and microhardness of composites increased but the elongation decreased.In addition,the tensile strength and microhardness of composite samples were higher than those of monolithic Al.The density measurements revealed that the density of composites decreased with increasing content of the B₄C particles.     

The impact of dual-market on supply chain configuration for new products

Given a firm’s supply chain network, the key objective of supply chain configuration (SCC) is to determine a subset of supply chain partners to be involved in development, sourcing, production, distribution and support of a new product at the highest level of efficiency and expected responsiveness. Current literature on SCC realises the importance of considering the demand dynamics associated with the new product diffusion (NPD). However, these studies assume one-segment market for new products, a single homogenous consumer segment. Recent research in marketing indicates that such simplification might be fatal because a diverse and significant number of product categories may experience a dual-market structure, namely early and main markets, and generate a different demand dynamics. The objectives of this study are to: (i) develop a hybrid optimisation model, capturing both SCC decisions and the demand dynamics of dual-market NPD process; (ii) based on real-world data for a host of electronic product categories, various SCC networks and NPD demand dynamics, examine the new integrated optimisation model under one- and two-segment market; and (iii) present relevant managerial implications and guidelines for supply chain and marketing managers. Our extensive comparative computational experiment with 26 categories of consumer electronic products show that on average the relative net profit may improve significantly, when the market is considered as two-segment.     

Highly selective optical nitrite sensor for food analysis based on Lauth’s violet-triacetyl cellulose membrane film

A new sensor has been developed for the determination of nitrite based on the immobilisation of Lauth’s violet on triacetyl cellulose membrane using absorption spectrophotometry. The optical sensor signal is based on the reaction of Lauth’s violet with bromate as an oxidant in the presence of nitrite to produce a colourless product. Nitrite has a strong catalytic effect on the oxidation of Lauth’s violet with bromate in acidic media. The difference in the absorbance of the optode at 617 nm between uncatalysed and catalysed reactions (ΔA) was directly proportional to the concentration of nitrite in sample solution. A linear calibration curve (r² = 0.985) was observed in the nitrite concentration range of 10.12-1012 ng mL⁻¹ and a detection limit of 8.3 ng mL⁻¹ was found.     

Environmental selenium research: from microscopic processes to global understanding

Selenium is a natural trace element that is of fundamental importance to human health. The extreme geographical variation in selenium concentrations in soils and food crops has resulted in significant health problems related to deficient or excess levels of selenium in the environment. To deal with these kinds of problems in the future it is essential to get a better understanding of the processes that control the global distribution of selenium. The recent development of analytical techniques and methods enables accurate selenium measurements of environmental concentrations, which will lead to a better understanding of biogeochemical processes. This improved understanding may enable us to predict the distribution of selenium in areas where this is currently unknown. These predictions are essential to prevent future Se health hazards in a world that is increasingly affected by human activities.     

Directed differential connectivity graph of interictal epileptiform discharges

In this paper, we study temporal couplings between interictal events of spatially remote regions in order to localize the leading epileptic regions from intracerebral EEG (iEEG). We aim to assess whether quantitative epileptic graph analysis during interictal period may be helpful to predict the seizure onset zone of ictal iEEG. Using wavelet transform, cross-correlation coefficient, and multiple hypothesis test, we propose a differential connectivity graph (DCG) to represent the connections that change significantly between epileptic and nonepileptic states as defined by the interictal events. Postprocessings based on mutual information and multiobjective optimization are proposed to localize the leading epileptic regions through DCG. The suggested approach is applied on iEEG recordings of five patients suffering from focal epilepsy. Quantitative comparisons of the proposed epileptic regions within ictal onset zones detected by visual inspection and using electrically stimulated seizures, reveal good performance of the present method.     

Preliminary Results of IS Plasma Focus as a Breeder of Short-Lived Radioisotopes 12C(d,n)13N

Modified IS (Iranian Sun) plasma focus (10 kJ,15 kV, 94 ??F, 0.1 Hz) has been used to produce the short-lived radioisotope ¹³N (half-life of 9.97 min) through ¹²C(d,n)¹³N nuclear reaction. The filling gas was 1.5?C3 torr of hydrogen (60%) deuterium (40%) mixture. The target was solid nuclear grade graphite with 5 mm thick, 9 cm width and 13 in length. The activations of the exogenous target on average of 20 shots (only one-third acceptable) through 10?C13 kV produced the 511 keV gamma rays. Another peak found at the 570 keV gamma of which both was measured by a NaI portable gamma spectrometer calibrated by a ¹³⁷Cs 0.25 ??Ci sealed reference source with its single line at 661.65 keV and ²²Na 0.1 ??Ci at 511 keV. To measure the gamma rays, the graphite target converts to three different phases; solid graphite, powder graphite, and powder graphite in water solution. The later phase approximately has a doubled activity with respect to the solid graphite target up to 0.5 ??Ci of 511 keV and 1.1 ??Ci of 570 keV gamma lines were produced. This increment in activity was perhaps due to structural transformation of graphite powder to nano-particles characteristic in liquid water.     

Yellow–Orange Electroluminescence of Novel Tin Complexes

Novel tin complexes were synthesized for use as fluorescent materials in organic light-emitting diodes (OLEDs). The structures of these complexes were characterized by ultraviolet–visible, Fourier-transform infrared, and nuclear magnetic resonance spectroscopy methods and elemental analyses. The energy levels of the tin complexes were determined using cyclic voltammetry measurements. Devices were fabricated with an indium tin oxide (ITO)/PEDOT:PSS (90 nm)/PVK:PBD:tin complexes (75 nm)/Al (180 nm) structure; the resultant devices had peak emissions ranging from 537 nm to 580 nm. The tin complexes accounted for 8 wt.% of the blend in the PVK:PBD (100:40), which was used as a host. The electroluminescent spectra of the tin complexes were red-shifted as compared with the PVK:PBD blend. We believe that the electroluminescence performance of OLED devices based on tin complexes relies on overlaps between the absorption of the tin compounds and the emission of PVK:PBD.     

The effect of sintering time on the densification and mechanical properties of a mechanically alloyed Cr–Mn–N stainless steel

Sintering is an essential stage in powder metallurgy, which affects the final microstructure and performance of the part. This study is concerned with the sintering and mechanical behaviors of Fe–18Cr–8Mn–0.9N stainless steel prepared from mechanically alloyed amorphous/nanocrystalline powders. The contribution of sintering time to the densification at 1100 °C is considered and a sluggish densification is found for the alloy. Furthermore, the correlation between the microstructure and mechanical properties of the fabricated porous parts is studied. It is found that the yield stress is affected by both porosity and the material’s intrinsic yield strength. Nonetheless, the effect of porosity on the overall hardness typically prevails over the effect of matrix hardness. Interestingly, even after sintering at 1100 °C for up to 20 h, the nanometric structure of the material is retained.     

Fast LV motion estimation using subspace approximation techniques

Cardiac motion estimation is very important in understanding cardiac dynamics and in noninvasive diagnosis of heart disease. Magnetic resonance (MR) imaging tagging is a technique for measuring heart deformations. In cardiac tagged MR images, a set of dark lines are noninvasively encoded within myocardial tissue providing the means for measurement of deformations of the heart. The points along tag lines measured in different frames and in different directions carry important information for determining the three-dimensional nonrigid movement of left ventricle. However, these measurements are sparse and, therefore, multidimensional interpolation techniques are needed to reconstruct a dense displacement field. In this paper, a novel subspace approximation technique is used to accomplish this task. We formulate the displacement estimation as a variational problem and then project the solution into spline subspaces. Efficient numerical methods are derived by taking advantages of B-spline properties. The proposed technique significantly improves our previous results reported in [3] with respect to computational time. The method is applied to a temporal sequence of two-dimensional images and is validated with simulated and in vivo heart data.