Influence of Cobalt Doping on the Physical Properties of Zn<Subscript>0.9</Subscript>Cd<Subscript>0.1</Subscript>S Nanoparticles

Zn_0.9Cd_0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn_0.9Cd_0.1S sphalerite phase. For low cobalt concentration (≤0.05 M) particle size, d _XRD is ~3.5 nm, while for high cobalt concentration (>0.05 M) particle size decreases abruptly (~2 nm) as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm) irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.     

Fatigue reliability under multiple-amplitude loads

A method to determine the fatigue of structures subjected to multiple-amplitude loads is presented. Unlike the more common cumulative damage methods, which are usually based on fatigue life data, the proposed method is based on tensile strength data. Assuming the Weibull distribution for the initial tensile strength and the fatigue life, the probability distributions for the residual tensile strength in both the crack initiation and the crack propagation stages of fatigue are determined. The method is illustrated for two-amplitude loads by means of experimental results obtained by testing specimens of a structural steel and is shown to be more accurate than the Palmgren-Miner cumulative damage method.     

Extrusion blown films of poly(lactic acid) chain‐extended with food grade multifunctional epoxies

The effectiveness and efficiency of two food grade multifunctional epoxies with low and high epoxy equivalent weights in chain extending/branching poly(lactic acid) (PLA) were studied in a torque rheometer. Processing PLA and chain extender (CE) at 200°C for 300 s not only chain‐extended PLA effectively as indicated by a significant increase in the mixing torque as well as PLA's melt viscosity and molecular weight, but also branched it leading to its reduced crystallinity. Chain extension occurred through the ring opening reaction of epoxy groups in the CE with PLA's hydroxyl and/or carboxyl groups. CE with lower epoxy equivalent weight was more efficient due to its higher reactivity. Secondly, the processabilities of PLA films chain‐extended and branched with various amounts of the most efficient CE were assessed. Like in torque rheometer, chain extension and branching also occurred during film production as indicated by PLA's increased molecular weight and decreased crystallinity when blended with CE. However, film manufacture was feasible only for blends with up to 0.5% CE, becoming unprocessable above this content due to chain entanglement leading to increased viscosity. Chain extension/branching of PLA was beneficial in overcoming film's brittleness since its impact strength increased almost linearly with the CE content. POLYM. ENG. SCI., 59:2211–2219, 2019. © 2019 Society of Plastics Engineers     

Visualizing Thermally Activated Memristive Switching in Percolating Networks of Solution-Processed 2D Semiconductors

Memristive systems present a low-power alternative to silicon-based electronics for neuromorphic and in-memory computation. 2D materials have been increasingly explored for memristive applications due to their novel biomimetic functions, ultrathin geometry for ultimate scaling limits, and potential for fabricating large-area, flexible, and printed neuromorphic devices. While the switching mechanism in memristors based on single 2D nanosheets is similar to conventional oxide memristors, the switching mechanism in nanosheet composite films is complicated by the interplay of multiple physical processes and the inaccessibility of the active area in a two-terminal vertical geometry. Here, the authors report thermally activated memristors fabricated from percolating networks of diverse solution-processed 2D semiconductors including MoS₂, ReS₂, WS₂, and InSe. The mechanisms underlying threshold switching and negative differential resistance are elucidated by designing large-area lateral memristors that allow the direct observation of filament and dendrite formation using in situ spatially resolved optical, chemical, and thermal analyses. The high switching ratios (up to 10³) that are achieved at low fields (≈4 kV cm⁻¹) are explained by thermally assisted electrical discharge that preferentially occurs at the sharp edges of 2D nanosheets. Overall, this work establishes percolating networks of solution-processed 2D semiconductors as a platform for neuromorphic architectures.     

Experimental study on fluidisation behaviour and pressure drop across the centrifugal fluidised bed with static geometry by varying inlets,inlet width and mass of bed particles

Centrifugal fluidised bed with static geometry (CFBSG) is the novel approach of fluidisation which has not yet attracted the attention of IC engine researchers to remove particulate matter. This requires necessitating an understanding of the nature of fluidisation and pressure drop in CFBSG. The present study describes an experimental study on the effect of a number of inlets, inlet width, and mass of bed particles silicon carbide (SiC) on fluidisation and pressure drop across the fluidised bed chamber using air as a medium. Low pressure drop and better partial fluidisation were observed for three- and four-inlet chambers, especially at a higher loading of bed particles. The accumulation of bed particles near inlet and outlet is also drastically reduced as the number of inlet increases. When compared to 5?mm inlet slot chambers, 3?mm inlet slot chambers for any inlet gives better fluidisation with higher pressure drop.     

Spray pyrolytically deposited nanoporous Ti doped hematite thin films for efficient photoelectrochemical splitting of water

Nanoporous hematite (α-Fe₂O₃) thin films doped with Ti⁴⁺ deposited by spray-pyrolysis were successfully used in photoelectrochemical splitting of water for solar hydrogen production. X-ray diffraction, field emission scanning electron microscopy, UV–visible absorption and photoelectrochemical studies have been performed on the undoped and Ti⁴⁺ doped hematite thin films. Morphology of α-Fe₂O₃ thin films was observed to be nanoporous, with increased porosity (pore size ∼12 to 20 nm) on increasing doping concentration. A significant decrease in the bandgap energy from 1.95 to 1.27 eV was found due to doping. α-Fe₂O₃ film doped with 0.02 M Ti⁴⁺ ions exhibited best solar to hydrogen conversion efficiency (photoconversion efficiency) of 1.38% at 0.5 V/SCE. Highest photocurrent densities of 0.34 mA/cm² at zero bias and 1.98 mA/cm² at 0.5 V/SCE were obtained by incorporating 0.02 M Ti⁴⁺ in α-Fe₂O₃, which are significantly larger than earlier reported values. Donor density (30.8 × 10²⁰ cm⁻³) and flatband potential (−1.01 V/SCE) obtained were also maximum for this sample. Hydrogen collected in 1 hr at Pt electrode with the best photoelectrode was 2.44 mL with 150 mW/cm² visible light source.     

The Organization of the Quorum Sensing luxI/R Family Genes in Burkholderia

Members of the Burkholderia genus of Proteobacteria are capable of living freely in the environment and can also colonize human, animal and plant hosts. Certain members are considered to be clinically important from both medical and veterinary perspectives and furthermore may be important modulators of the rhizosphere. Quorum sensing via N-acyl homoserine lactone signals (AHL QS) is present in almost all Burkholderia species and is thought to play important roles in lifestyle changes such as colonization and niche invasion. Here we present a census of AHL QS genes retrieved from public databases and indicate that the local arrangement (topology) of QS genes, their location within chromosomes and their gene neighborhoods show characteristic patterns that differ between the known Burkholderia clades. In sequence phylogenies, AHL QS genes seem to cluster according to the local gene topology rather than according to the species, which suggests that the basic topology types were present prior to the appearance of current Burkholderia species. The data are available at http://net.icgeb.org/burkholderia/.     

Combining Surface Water with Mine Water to Improve the Removal of Natural Organic Matter by Enhanced Coagulation

Mine Water and the Environment - Mixing of near-neutral pH mine water and surface water substantially reduced the reactive portion of the natural organic matter (NOM) in the surface water by...     

The paraneuronal gill neuroendocrine system in ocellated puffer fish Leiodon cutcutia

Pseudobranchial neurosecretory system (PSNS) is the third Neuroendocrine (NE) system found in the gill region of fishes in close association with pseudobranch/carotid labyrinth/carotid gland and can suitably be placed under the category of “Diffused NE system (DNES).” The cells belonging to this system fall under the category of “Paraneurons,” a concept proposed by Fujita and coworkers. It is found uniformly in all the catfish species and some other noncatfish group of teleosts as Atheriniformes, Channiformes, Perciformes, and Clupeiformes. The fishes, in which the PSNS is present, belong to different breathing habits. Most of these have the capacity to tolerate low O₂ conditions. Leiodon cutcutia although not an air‐breathing fish, is known to retain air in its stomach for varied periods when threatened. In an attempt to verify the veracity of this system in a fish of another peculiar breathing habit, ocellated puffer fish L. cutcutia (order Tetradontiformes) was investigated. The histological observations undertaken on L. cutcutia revealed the presence of a well‐developed extrabranchial NE system. The findings are discussed in the light of the association of PSNS with chemosensory system and its evolution in fishes, especially in the view of the transition from aquatic to terrestrial life.