Resistive switching memory characteristics of Ge/GeOx nanowires and evidence of oxygen ion migration

The resistive switching memory of Ge nanowires (NWs) in an IrO_x/Al₂O₃/Ge NWs/SiO₂/p-Si structure is investigated. Ge NWs with an average diameter of approximately 100 nm are grown by the vapor–liquid-solid technique. The core-shell structure of the Ge/GeO_x NWs is confirmed by both scanning electron microscopy and high-resolution transmission electron microscopy. Defects in the Ge/GeO_x NWs are observed by X-ray photoelectron spectroscopy. Broad photoluminescence spectra from 10 to 300 K are observed because of defects in the Ge/GeO_x NWs, which are also useful for nanoscale resistive switching memory. The resistive switching mechanism in an IrO_x/GeO_x/W structure involves migration of oxygen ions under external bias, which is also confirmed by real-time observation of the surface of the device. The porous IrO_x top electrode readily allows the evolved O₂ gas to escape from the device. The annealed device has a low operating voltage (<4 V), low RESET current (approximately 22 μA), large resistance ratio (>10³), long pulse read endurance of >10⁵ cycles, and good data retention of >10⁴ s. Its performance is better than that of the as-deposited device because the GeO_x film in the annealed device contains more oxygen vacancies. Under SET operation, Ge/GeO_x nanofilaments (or NWs) form in the GeO_x film. The diameter of the conducting nanofilament is approximately 40 nm, which is calculated using a new method.     

FSAP Protects against Histone-Mediated Increase in Endothelial Permeability In Vitro

Factor-VII-activating protease (FSAP) is involved in the regulation of hemostasis and inflammation. Extracellular histones play a role in inflammation and the conversion of latent pro-FSAP into active FSAP. FSAP has been shown to regulate endothelial permeability, but the mechanisms are not clear. Here, we have investigated the effects of FSAP on endothelial permeability in vitro. A mixture of histones from calf thymus stimulated permeability, and the wild-type (WT) serine protease domain (SPD) of FSAP blocked this effect. WT–SPD–FSAP did not influence permeability on its own, nor that stimulated by thrombin or vascular endothelial growth factor (VEGF)-A₁₆₅. Histones induced a large-scale rearrangement of the junction proteins VE-cadherin and zona occludens-1 from a clear junctional distribution to a diffuse pattern. The presence of WT–SPD–FSAP inhibited these changes. Permeability changes by histones were blocked by both TLR-2 and TLR4 blocking antibodies. Histones upregulated the expression of TLR-2, but not TLR-4, in HUVEC cells, and WT–SPD–FSAP abolished the upregulation of TLR-2 expression. An inactive variant, Marburg I (MI)–SPD–FSAP, did not have any of these effects. The inhibition of histone-mediated permeability may be an important function of FSAP with relevance to sepsis, trauma, and stroke and the need to be investigated further in in vivo experiments.     

Photoactive Lanthanide-Based Upconverting Nanoclusters for Antimicrobial Applications

Developing photoactive nanosystems against microbial infection and its therapeutic application is compromised by the lack of suitable materials or molecular dyes activatable at biofriendly NIR light. In this direction, the upconverting nanoparticles based on core–shell lanthanide-doped nanoclusters are developed synthetically to achieve a broad range of NIR-active phototherapeutic antimicrobial agents. This review illustrates antimicrobial photodynamic therapy (aPDT) and multimodal therapy by NIR photoirradiation, generated by lanthanum doped upconverting nanoparticles (UCNPs). The objective herein is to discuss the insights in developing the UCNPs for designing efficient aPDTs and their efficacies against emerging antibiotic-resistant bacterial colonies and their biofilms, drug-resistant fungi, and viruses. The biosafety and biocompatibility of UCNPs at both in vitro and in vivo level are also presented in detail. Finally, our perspectives on the ways of future material engineering needed for the effective translation into their real-world applications are also commented.     

Medium resolution magneto-optical Faraday rotation measurement system

Medium resolution magneto-optic Faraday rotation measurement setup has been reported. Measuremental setup reported is made up of simple polarized laser source, beam expander, analyzer and a bisected cross polarizedp-n detector for single ended measurements. Result of CoO modified yttrium iron garnet (YIG) films showed a rotation of 3 deg/μm which is comparable to earlier reported Co-doped YIG films. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

Local open‐ and closed‐loop manipulation of multiagent networks

The manipulation of networked cyberphysical devices via local external actuation or feedback control is explored, in the context of a canonical multiagent dynamical system that is engaged in a consensus or synchronization task. One main focus is to understand whether or not, and how easily, a stakeholder can manipulate the full network's dynamics by hijacking only one agent's actuation signal. Explicit spectral characterizations are given of the energy (effort) required to manipulate the dynamics. These characterizations are used to (1) gain structural insights into ease of manipulation, (2) show that manipulation along the consensus manifold is easy, and (3) address network design to enable or prevent manipulation. Additionally, it is shown that the multiagent system can be manipulated effectively along the consensus manifold using local feedback controls, which do not require model knowledge or wide‐area measurements.     

Influence of combined electromagnetohydrodynamics on microchannel flow with electrokinetic effect and interfacial slip

We investigate analytically the combined consequences of electromagnetohydrodynamic forces and interfacial slip on streaming potential mediated pressure-driven flow in a microchannel. Going beyond traditional Debye–Hückel limit, we first derive a closed-form analytical solution for velocity field by considering nonlinear electrical potential distribution, wall slip effects, externally imposed transverse magnetic field, and laterally applied electric field in the plane of flow. The effects of electrical double-layer (EDL) formation and the consequent interfacial phenomena are critically examined under such situations. An expression for induced streaming potential in the microchannel is deduced considering EDL formation and the consequences of finite conductance of the immobilized Stern layer. This simplified analytical expression is later on critically assessed against three-dimensional simulation paradigm of streaming potential mediated flows, which is a first effort of this kind. We demonstrate that flow rate increases progressively with increasing surface potential and eventually approaches to a limiting value. Combination of electromagnetohydrodynamic effect with liquid slip is shown to amplify the flow rate, even at lower values of surface potential. Our study brings out the possibility of achieving an optimum flow rate by judicious application of combined electromagnetohydrodynamics. The present analysis has significant consequence in the design of advanced microfluidic devices with improved efficiency and functionality.     

Biomaterial Based Polyurethane Adhesive for Bonding Rubber and Wood Joints

An intermediate compound for synthesizing polyester polyol was prepared from glycosylation of potato starch by reacting it with ethylene glycol in presence of sulphuric acid. Glycol glycoside thus prepared was characterized by HPLC and FTIR. This polyhydroxy compound was replaced in varying amounts with trimethylolpropane for polyester polyol synthesis. Sebacic acid was used as dicarboxylic acid along with castor oil for polyester polyol formulation. Polyols were reacted with toluene 2,4-diisocyanate adduct for polyurethane formation. Polyester polyol and polyurethane were characterized by FTIR. Polyurethane was utilized for bonding wood as well as rubber joints. Bond strength was measured by means of lap shear strength and peel strength for wood and rubber joints, respectively. Chemical resistance of polyurethane adhesive was also evaluated. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the Relation of Microstructure and Texture Evolution in an Austenitic Fe-28Mn-0.28C TWIP Steel During Cold Rolling

In the present study, microstructure and texture evolution in an austenitic Fe-28 wt pct Mn-0.28 wt pct C TWIP steel in the range between 10 and 80 pct reduction by cold rolling were systematically analyzed. The formation of the observed microstructural features occurred in three different stages: I (10 to 20 pct)—mainly slip lines, grain elongation, and formation of few twin-matrix lamellae; II (30 to 50 pct)—severe increase of the volume fraction of twins, alignment of twins with the rolling plane, and formation of microshear bands; and III (60 to 80 pct)—further alignment of twins, evolution of a herring bone structure, and macroshear bands. In contrast to most f.c.c. metals, the transition from Copper- to Brass-type texture occurred at low strain levels (30 pct). This behavior is attributed to the early formation of deformation twins in the material and can be related to the SFE of this high manganese steel. At higher reduction levels, microscopic (≥40 pct) and macroscopic shear band formation (≥60 pct) contributed to the increase of randomly oriented grains, mainly at the expense of the Brass component. Furthermore, the formation of the Goss component and of the 〈111〉//ND fiber (γ) is attributed to severe twin formation.