Co-Doped MoSe2 Nanoflowers as Efficient Catalysts for Electrochemical Hydrogen Evolution Reaction (HER) in Acidic and Alkaline Media

Transition metal dichalcogenides (TMDCs) based materials are considered as highly active alternatives to the precious Pt-based catalysts for the hydrogen evolution reaction (HER). In particular, MoSe₂ emerges as a promising catalyst due to its abundance and electrochemical stability, but further modifications are still required to enhance its performance, specifically in alkaline conditions. Here, we developed a method to obtain MoSe₂ with two cobalt doping patterns: homogeneously doped and edge doped nanoflowers, with abundant edge sites and extended surface area. The results show that low concentration of doping enhances the catalytic activity toward HER. Incorporation of cobalt as a substituent dopant within the layered structure of MoSe₂ appears to have two major contributions: it changes the chemical environment providing more active sites with favored hydrogen adsorption properties, and improves the charge transfer resistance and thus facilitates the HER kinetics. Moreover, the homogeneous and edge-doped nanoflowers show different pH-dependence of HER activity. Edge-doped samples exhibit significantly improved performance in acidic medium, while the overpotential increases in alkaline environment upon doping. A mechanistic explanation of the observed effect is proposed. This work opens up an additional path for improving the catalytic activity of TMDCs in acidic or alkaline medium using a simple and facile method with only small quantities of dopants.     

Neuroprotective Effect of Nerve Growth Factor Loaded in Porous Silicon Nanostructures in an Alzheimer's Disease Model and Potential Delivery to the Brain

Nerve growth factor (NGF) plays a vital role in reducing the loss of cholinergic neurons in Alzheimer's disease (AD). However, its delivery to the brain remains a challenge. Herein, NGF is loaded into degradable oxidized porous silicon (PSiO₂) carriers, which are designed to carry and continuously release the protein over a 1 month period. The released NGF exhibits a substantial neuroprotective effect in differentiated rat pheochromocytoma PC12 cells against amyloid‐beta (Aβ)‐induced cytotoxicity, which is associated with Alzheimer's disease. Next, two potential localized administration routes of the porous carriers into murine brain are investigated: implantation of PSiO₂ chips above the dura mater, and biolistic bombardment of PSiO₂ microparticles through an opening in the skull using a pneumatic gene gun. The PSiO₂‐implanted mice are monitored for a period of 8 weeks and no inflammation or adverse effects are observed. Subsequently, a successful biolistic delivery of these highly porous microparticles into a live‐mouse brain is demonstrated for the first time. The bombarded microparticles are observed to penetrate the brain and reach a depth of 150 µm. These results pave the way for using degradable PSiO₂ carriers as potential localized delivery systems for NGF to the brain.     

Automatic endocardial-boundary detection in low mechanical-index contrast echocardiography

This paper presents a novel algorithm, aimed at automatic endocardial boundary (inner boundary) detection in myocardial opacification scenarios. The data acquisition protocol uses (on purpose) low mechanical index imaging (i.e., weak ultrasound signal), so that the acquired images are characterized by low signal-to-noise ratios. The proposed algorithm is based on converting the frames, given in Cartesian coordinates, into polar coordinates, and applying a set of filters in order to compute the initial estimation of the endocardial boundary. The final estimation of the endocardial boundary is produced by an error correction process, which uses both spatial and temporal filtering. The estimated boundaries are converted into Cartesian coordinates, for display. Our algorithm has been tested on nine cine-loops. The resulting myocardial outlines have been separately assessed by two clinicians, scoring each segment in each cine-loop on a scale between 5 (excellent) and 1 (completely unacceptable). The mean overall score is 3.8 +/- 0.8, which seems adequate. The same clinicians have also manually drawn the contours of the endocardial boundary for the end-systolic and the end-diastolic frames of each cine-loop. The results show, that the mismatch between the automatically determined outlines and the manually drawn outlines is of the same order of magnitude as the interobserver variability. These results further support the validity of our method.     

"Phytoscreening": the use of trees for discovering subsurface contamination by VOCs

We tested the possibility of using tree cores to detect unknown subsurface contamination by chlorinated volatile organic compounds (Cl-VOCs) and petroleum hydrocarbons, a method we term "phytoscreening". The scope and limitations of the method include the following: (i) a number of widespread Cl-VOC contaminants are readily found in tree cores, although those with very high vapor pressures or low boiling points may be absent; (ii) volatile petroleum hydrocarbons were notwell-expressed in tree cores; (iii) trees should be sampled during active evapotranspiration and from directions that are well exposed to sunlight; (iv) there is not necessarily a direct correlation between concentrations measured in tree cores and those in the subsurface; (v) detection of a contaminant in a tree core indicates that the subsurface is contaminated with the pollutant; (vi) many possible causes of false negatives may be predicted and avoided. We sampled trees at 13 random locations in the Tel Aviv metropolitan area and identified Cl-VOCs in tree coresfromthree locations. Subsequently, subsurface contamination at all three sites was confirmed. Phytoscreening is a simple, fast, noninvasive, and inexpensive screening method for detecting subsurface contamination, and is particularly useful in urban settings where conventional methods are difficult and expensive to employ.     

Monitoring techniques for phased-array antennas

The problem of monitoring phased-array antennas in general and microwave landing system (MLS) in particular is considered. Various methods of monitoring phased-array antennas are suggested. One is based on changes in the far-field radiation pattern arising from defects in the array. Another method uses the near-field to far-field transformation, based on the concept of the plane-wave spectrum, for the detection of defects in the antenna. A third method is based on near-field measurements and uses the properties of the Fresnel integral. The methods were simulated on the computer and, where possible, were tested by experiment. A comparative assessment of the methods is given, and an operational monitoring system is suggested for the MLS phased army.     

Preference-Based Constrained Optimization with CP-Nets

Many artificial intelligence (AI) tasks, such as product configuration, decision support, and the construction of autonomous agents, involve a process of constrained optimization, that is, optimization of behavior or choices subject to given constraints. In this paper we present an approach for constrained optimization based on a set of hard constraints and a preference ordering represented using a CP-network—a graphical model for representing qualitative preference information. This approach offers both pragmatic and computational advantages. First, it provides a convenient and intuitive tool for specifying the problem, and in particular, the decision maker's preferences. Second, it admits an algorithm for finding the most preferred feasible (Pareto-optimal) outcomes that has the following anytime property: the set of preferred feasible outcomes are enumerated without backtracking. In particular, the first feasible solution generated by this algorithm is Pareto optimal.     

Guest Editors' Introduction: Micro's Top Picks from the Microarchitecture Conferences

The guest editors introduce this special issue showcasing Micro's Top Picks from the Microarchitecture Conferences of 2006. They describe the issue's intensive submission and selection process. The articles focus on the design of resilient computing systems, the architecture of multicore systems, performance evaluation techniques, general-purpose processors, and a programmable architecture for wireless protocols.     

Sources of nitrates in groundwater of the coastal plain of Israel Evolution of ideas

A critical review of the studies conducted on the problem of nitrate pollution of the Coastal Plain aquifer of Israel is presented. The quantitative nitrogen balance of the aquifer is analyzed based on the reconstructed average nitrate trends in groundwater. This balance indicates that most of the nitrates found today in the aquifer reached the water table in the period 1930–1960. We suggest that the mineralization of the organic matter in the soil and unsaturated zone was the main source of nitrate pollution. The steep rise in the average nitrate concentration of groundwater over the last 50 years was the inevitable result of the agricultural development of the area. If no large transient nitrate reservoir exists in the unsaturated and water table zones, it is expected that the average nitrate content of groundwater will decrease with time.