Multifunctional Optoelectronics via Harnessing Defects in Layered Black Phosphorus

Layered black phosphorus (BP), a promising 2D material, tends to oxidize under ambient conditions. While such defective BP is typically considered undesirable, defect engineering has in fact been exploited in contemporary materials to create new behaviors and functionalities. In this spirit, new opportunities arising from intrinsic defect states in BP, particularly through harnessing unique photoresponse characteristics, and demonstrating three distinct optoelectronic applications are demonstrated. First, the ability to distinguish between UV‐A and UV‐B radiations using a single material that has tremendous implications for skin health management is shown. Second, the same device is utilized to show an optically stimulated mimicry of synaptic behavior opening new possibilities in neuromorphic computing. Third, it is shown that serially connected devices can be used to perform digital logic operations using light. The underpinning photoresponse is further translated on flexible substrates, highlighting the viability of the technology for mechanically conformable and wearable systems. This demonstration paves the way toward utilizing the unexplored potential offered by defect engineering of 2D materials for applications spanning across a broad range of disciplines.     

Fluid Dynamics Effects on Microstructure Prediction in Single-Laser Tracks for Additive Manufacturing of IN625

Metallurgical and Materials Transactions B - Single-track laser fusion were simulated using a heat-transfer-solidification-only (HTS) model and its extension with fluid dynamics (HTS_FD) model...     

Web Based Capacity Allocation Strategies for Customers with Heterogeneous Preferences

We study different mechanisms for the pricing and allocation of capacity to customers with heterogeneous and unknown preferences. The mechanisms we study include posting of prices, auctions, with and without the possibility of resale. We compare the performance of each mechanism with the optimal selling procedure in terms of expected seller's profit and efficiency. We also discuss the feasibility of web based implementation.     

Neuro-Fuzzy Control of Railcar Vibrations Using Semiactive Dampers

Abstract:   This article describes a new approach to reducing vertical vibrations in a 70-ton railcar using a neuro-fuzzy controller and a magnetorheological (MR) damper. A semiactive control technique is developed for a two-degree-of-freedom quarter car model of the railcar that has an installed MR damper. A fuzzy controller in real time continuously updates damping properties of the device. The controller uses feedback acceleration of the freight mass to specify a voltage signal to the MR damper. Correlations between acceleration (controller input) and voltage applied to the MR damper (controller output) are developed using Neuro Fuzzy Controller (NEFCON). To assess effectiveness of the semiactive control scheme, responses of the railcar to various haul conditions are compared with those for uncontrolled and for passive operating conditions of the MR damper. Results indicate that semiactively controlled MR dampers can reduce vibrations to acceptable levels provided that sufficient force capacity can be supplied by the damper .     

Donor‐Induced Performance Tuning of Amorphous SrTiO3 Memristive Nanodevices: Multistate Resistive Switching and Mechanical Tunability

Metal–oxide valence‐change memristive devices are the key contenders for the development of multilevel nonvolatile analog memories and neuromorphic computing architectures. Reliable low energy performance and tunability of nonlinear resistive switching dynamics are essential to streamline the high‐density circuit level integration of these devices. Here, manipulation of room temperature‐synthesized defect chemistry is employed to enhance and tune the switching characteristics of high‐performance amorphous SrTiO₃ (a‐STO) memristors. Substitutional donor (Nb) doping with low concentrations in the a‐STO oxide structure allows extensive improvements in energy requirements, stability, and controllability of the memristive performance, as well as field‐dependent multistate resistive switching. Evidence is presented that room temperature donor doping results in a modified insulator oxide where dislocation sites act as charge carrier modulators for low energy and multilevel operation. Finally, the performance of donor‐doped a‐STO‐based memristive nanodevices is showcased, with the possibility of mechanical modulation of the nonlinear memristive characteristics of these devices demonstrated. These results highlight the potential of donor‐doped a‐STO nanodevices for high‐density integration as analog memories and multifunctional alternative logic elements.     

Concentrated Fenofibrate Nanoparticle Suspensions from Melt Emulsification for Enhanced Drug Dissolution

Concentrated fenofibrate (FNB) nanoparticle suspensions are produced via an oil/water melt emulsification process from the micronized drug particles dispersed in water above the drug melting point. Sonication energy enables forming nanosized melt droplets, and nanosized solid particles upon subsequent cooling. Stabilization achieved via surface‐active molecules is necessary to prevent coalescence of the droplets or agglomeration of the solid nanoparticles. Judicious selection of stabilizer and concentration resulted in 150‐nm drug particles with solid loading up to 30 %. The hydrophilic‐lipophilic‐balance concept is applicable, facilitating selection of surfactants based on their chemical structure. The strong in vitro dissolution rate enhancement suggests improved FNB bioavailability.     

Biodegradable polymer blends of poly(lactic acid) and poly(ethylene glycol)

Poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were melt-blended and extruded into films in the PLA/PEG ratios of 100/0, 90/10, 70/30, 50/50, and 30/70. It was concluded from the differential scanning calorimetry and dynamic mechanical analysis results that PLA/PEG blends range from miscible to partially miscible, depending on the concentration. Below 50% PEG content the PEG plasticized the PLA, yielding higher elongations and lower modulus values. Above 50% PEG content the blend morphology was driven by the increasing crystallinity of PEG, resulting in an increase in modulus and a corresponding decrease in elongation at break. The tensile strength was found to decrease in a linear fashion with increasing PEG content. Results obtained from enzymatic degradation show that the weight loss for all of the blends was significantly greater than that for the pure PLA. When the PEG content was 30% or lower, weight loss was found to be primarily due to enzymatic degradation of the PLA. Above 30% PEG content, the weight loss was found to be mainly due to the dissolution of PEG. During hydrolytic degradation, for PLA/PEG blends up to 30% PEG, weight loss occurs as a combination of degradation of PLA and dissolution of PEG. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1495–1505, 1997     

Enhanced thromboxane biosynthesis in patients with chronic obstructive pulmonary disease. The Chronic Obstructive Bronchitis and Haemostasis Study Group

Thrombotic complications of pulmonary circulation occur in patients with chronic obstructive pulmonary disease (COPD). In the present study, we sought to evaluate in vivo platelet activation through the measurement of 11/dehydro-thromboxane (Tx) B2 TxA2 major metabolite in the urine, in 29 patients with COPD, compared with 29 sex- and age-matched healthy subjects. The urinary excretion of 11-dehydro-TxB2 was significantly higher in patients with COPD than in control subjects: median (range), 753 (277-4,409) and 275 (129-612) pg/mg creatinine, respectively; p < 0.0001). Moreover, 11-dehydro-TxB2 excretion was inversely related with arterial oxygen tension (rho = -0.46; p = 0.0145). In five of the 29 patients a short-term therapeutic course with oxygen supplementation induced a significant decrease of urinary 11-dehydro-TxB2 excretion: median range, 941 (452-2,640) to 445 (166-1,560) pg/mg creatinine. Moreover, selective inhibition of platelet cyclooxygenase activity by low-dose aspirin was associated with more than 90% inhibition of thromboxane metabolite excretion, demonstrating its being of platelet origin. Plasma levels of prothrombin fragment F1 + 2 were higher in patients than in control subjects (2.6 +/- 1.5 versus 0.9 +/- 0.4 nM, p = 0.0001). No relation between 11-dehydro-TxB2 excretion and plasma F1 + 2 levels was found. We conclude that platelet TxA2 biosynthesis is enhanced in patients with COPD and may be influenced by arterial oxygen tension changes.     

Effects of hypnotically induced dreams on creative problem solving.

A wealth of anecdotal evidence supports the age-old notion that the nocturnal dream is a source for creative inspiration. Unfortunately, scientific research on so-called creative dreaming has not been forthcoming. Using hypnosis in an effort to bring the phenomenon under experimental control, the present investigation induced dreams in 24 undergraduates representing a number of occupational and educational backgrounds. Each S was at an impasse in the course of working on an academic, vocational, avocational, or personal problem or project at the time of participation in the experiment. As hypothesized, when compared with a rational-cognitive treatment group that emphasized a linguistic and logical approach to creative problem solving, a significantly greater number of Ss who were administered the hypnotic dream treatment were able to overcome their creative blocks within 1 wk of treatment. Treatment success was assessed in accordance with criteria derived from an operational definition of creativity developed in the introduction. The hypothesis is considered to have received conditional support, pending the outcome of suggested research. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)