Experimental and physical approaches on a novel semiconducting-ionic membrane fuel cell

Semiconducting-ionic membranes (SIMs) have exhibited significant superiority to replace the conventional ionic electrolytes in solid oxide fuel cells (SOFCs). One interesting phenomenon is that the SIMs can successfully avoid the underlying short-circuiting issue and power losses while bringing significantly enhanced power output. It is crucial to understand the physics in such devices as they show distinct electrochemical processes with conventional fuel cells. We first presented experimental studies of a SIM fuel cell based on a composite of semiconductor LiCo_0.8Fe_0.2O₂ (LCF) and ionic conductor Sm-doped CeO₂ (SDC), which achieved a remarkable power density of 1150 mW cm^?2 at 550 °C along with a high open circuit voltage (OCV) of 1.04 V. Then, for the first time we used a physical model via combining a semiconductor-ionic contact junction with a rectifying layer which blocks the electron leakage to describe such unique SIM device and excellent performance. Current and power are the most important characteristics for the device, by introducing the rectifying layer we described the SIM physical nature and new device process. This work presented a new view on advanced SIM SOFC science and technology from physics.     

Highly porous and thermally stable tribopositive hybrid bimetallic cryogel to boost up the performance of triboelectric nanogenerators

There have been tremendous efforts made to investigate various materials to enhance the electrical performance of triboelectric nanogenerators (TENGs) but there is still demand for some techniques to further enhance the performance of tribomaterials. Therefore, we fabricated a bimetallic hybrid cryogel via cheap and facile UV-radiation as well as in situ reduction method. Fabricated TENG device made up of porous hybrid bimetallic cryogel film containing silver and gold nanoparticles as tribopositive material and poly dimethyl siloxane (PDMS) as a tribonegative layer with dimension of 1 × 2 cm² has the ability to produced output voltage of 262.14 V with current density of 27.52 mA/m² and 7.44 W/m² peak power density, which was sufficient to light up more than 120 white light emitting-diodes (LEDs). Porous and rough structure, interaction of nanoparticles was the reason behind the performance enhancement of tribopositive material. Thus, this study introduces a very stable and easily synthesized bimetallic hybrid cryogel as a tribopositive material to enhance the performance of tribomaterials to design high performance TENG devices.     

Characterization of Carnobacterium maltaromaticum LMA 28 for its positive technological role in soft cheese making

Carnobacterium maltaromaticum is a lactic acid bacterium isolated from soft cheese. The objective of this work was to study its potential positive impact when used in cheese technology. Phenotypic and genotypic characterization of six strains of C. maltaromaticum showed that they belong to different phylogenetic groups. Although these strains lacked the ability to coagulate milk quickly, they were acidotolerant. They did not affect the coagulation capacity of starter lactic acid bacteria, Lactococcus lactis and Streptococcus thermophilus, used in dairy industry. The impact of C. maltaromaticum LMA 28 on bacterial flora of cheese revealed a significant decrease of Psychrobacter sp. concentration, which might be responsible for cheese aging phenomena. An experimental plan was carried out to unravel the mechanism of inhibition of Psychrobacter sp. and Listeria monocytogenes and possible interaction between various factors (cell concentration, NaCl, pH and incubation time). Cellular concentration of C. maltaromaticum LMA 28 was found to be the main factor involved in the inhibition of Psychrobacter sp. and L. monocytogenes.     

Design and computational analysis of a metal hydride hydrogen storage system with hexagonal honeycomb based heat transfer enhancements-part A

In this study, design and performance analysis is carried out for a 10 kWh metal hydride based hydrogen storage system. The system is equipped with distinctive aluminium hexagonal honeycomb based heat transfer enhancements (HTE) having higher surface area to volume ratio for effective heat transfer combined with low system weight addition. The system performance was studied under different operating conditions. The optimum absorption condition was achieved at 35 bar with water at room temperature as heat transfer fluid where up to 90% absorption was completed in 7200 s. The performance of the reactor was observed to significantly improve upon the addition of the HTE network at a minimal system weight penalty.     

Analysis of grey wolf optimizer based fractional order PID controller in speed control of DC motor

Microsystem Technologies - The present work deals with comparative and robustness analysis of grey wolf optimization (GWO) based fractional order proportional–integral derivative (FOPID)...     

Sarcoplasmic reticular Ca2+ pump ATPase activity in congestive heart failure due to myocardial infarction

OBJECTIVE: Earlier studies have shown a depression in the sarcoplasmic reticular (SR) Ca2+ uptake and gene expression in Ca2+ pump ATPase protein in congestive heart failure subsequent to myocardial infarction. It is the objective of this study to understand further the mechanisms of depressed SR Ca2+ pump activity in the failing heart. METHODS: Heart failure in rats was induced by occluding the left coronary artery for 16 weeks and the viable left ventricle was processed for the isolation of SR membranes. Sham-operated animals were used as control. The characteristics of SR Ca2+ pump ATPase in the presence of different concentrations of K+, Ca2+ and ATP were examined and the purity of these membranes was monitored by determining the marker enzyme activities. In addition to measuring changes in cyclic adenosine monophosphate (cAMP) protein kinase and Ca(2+)-calmodulin induced phosphorylation, alterations in SR phospholipid composition as well as sulfhydryl (SH) group content were investigated. RESULTS: Ca(2+)-stimulated ATPase activity, unlike Mg(2+)-ATPase activity, was depressed in the left ventricular SR from failing hearts as compared to control. The decrease in Ca(2+)-stimulated ATPase activity was seen at different concentrations of Ca2+, K+ and ATP but no changes in the affinities of the enzyme for Ca2+ and ATP were evident. The SR Ca(2+)-stimulated ATPase activities in the presence of both cAMP-dependent protein kinase and Ca(2+)-calmodulin were markedly decreased in the failing hearts when compared to control preparations. Furthermore, the 32P incorporation in the presence of cAMP-dependent protein kinase or Ca(2+)-calmodulin was also reduced in the experimental heart SR membranes. The phospholipid composition of the SR membranes from the failing heart was markedly altered. No changes in SH-group or the degree of cross contamination with other membranes were apparent in the failing heart SR. CONCLUSIONS: These results suggest that abnormalities in membrane phospholipid composition and phosphorylation of the enzyme may partly explain the observed depression in SR Ca2+ pump ATPase activity in heart failure following myocardial infarction.     

Design of a large-scale metal hydride based hydrogen storage reactor: Simulation and heat transfer optimization

An optimized design for a 210 kg alloy, TiMn alloy based hydrogen storage system for stationary application is presented. A majority of the studies on metal hydride hydrogen systems reported in literature are based on system scale less than 10 kg, leaving questions on the design and performance of large-scale systems unanswered. On the basis of sensitivity to various design and operating parameters such as thermal conductivity, porosity, heat transfer coefficient etc., a comprehensive design methodology is suggested. Following a series of performance analyses, a multi-tubular shell and tube type storage system is selected for the present application which completes the absorption process in 900 s and the desorption process in 2000 s at a system gravimetric capacity of 0.7% which is a vast improvement over similar studies. The study also indicates that after fifty percent reaction completion, heat transfer ceases to be the major controlling factor in the reaction. This could help prevent over-designing systems on the basis of heat transfer, and ensure optimum system weight.     

The influence of temperature and interface strength on the microstructure and performance of sol–gel silica–epoxy nanocomposites

A series of silica–epoxy nanocomposites were prepared by hydrolysis of tetraethoxysilane within the organic matrix at different processing temperatures, i.e., 25 and 60 °C. Epoxy matrices reinforced with 2.0–10.0 wt% silica were subsequently crosslinked with an aliphatic diamine hardener to give optically transparent nanocomposite films. Interphase connections between silica networks and organic matrix were established by in situ functionalization of silica with 2.0 wt% γ-aminopropyltriethoxysilane (APTS). The microstructure of silica–epoxy nanocomposites as studied by transmission electron microscopy indicated the formation of very well-matched nanocomposites with homogeneous distribution of silica at relatively higher temperatures and in the presence of APTS. Thermogravimetric and static mechanical analyses confirmed considerable increase in thermal stability, stiffness, and toughness of the modified composite materials as compared to neat epoxy polymer and unmodified silica–epoxy nanocomposites. A slight improvement in the glass transition temperatures was also recorded by differential scanning calorimetry measurements. High temperature of hydrolysis during the in situ sol–gel process not only improved reaction kinetics but also promoted mutual solubility of the two phases, and consequently enhanced the interface strength. In addition, APTS influenced the size and distribution of the inorganic domain and resulted in better performance of the modified silica–epoxy nanocomposites.     

Effects of silver nanoparticles on thermal properties of DBSA-doped polyaniline/PVC blends

Dodecylbenzenesulfonic acid (DBSA)-doped polyaniline (PAND) has been synthesized by redoping (PANDR) and aqueous polymerization (PANDA) methods. Silver nanoparticles were incorporated into the PANDR/tetrahydrofuran solution (PANDS) and then mixed with poly (vinyl chloride) (PVC) solution to prepare PANDS/PVC nanocomposites. In the present study, effects of silver nanoparticles on thermal properties of PAND/PVC blends have been investigated by employing thermal gravimetric analysis and heat flow microcalorimetry techniques. From these results it has been observed that the thermal stability of blends have increased by increasing the concentration of PAND in blends and nanocomposites. Addition of silver nanoparticles has suppressed the dehydrochlorination process and evolution/degradation of DBSA in PANDS/PVC nanocomposites. Presence of silver nanoparticles in PAND/PVC nanocomposites has reduced the mobility of PANI chains which in turn inhibited the transfer of free radicals formed during degradation of PAND and PVC through inter-chain reactions; hence, degradation process has been slowed down and thermal stability has been improved. Embedment of silver nanoparticles has reduced thermal weight loss corresponding to polymer degradation step and attains lower heat flow level in inert atmosphere for nanocomposites in contrast to those with no nanoparticles, thereby further improving thermal stability of nanocomposites. The heats of oxidation measured for blends and nanocomposites were independent of PAND/PVC blends composition.