Grain growth and pore coarsening in dense nano‐crystalline UO2+x fuel pellets

Dense nano‐sized UO_2+x pellets are synthesized by spark plasma sintering with controlled stoichiometries (UO_2.03 and UO_2.11) and grain sizes (~100 nm), and subsequently isothermally annealed to study their effects on grain growth kinetics and microstructure stability. The grain growth kinetics is determined and analyzed focusing on the interaction between grain boundary migration, pore growth, and coalescence. Grains grow much bigger in nano‐sized UO_2.11 than UO_2.03 upon thermal annealing, consistent with the fact that hyper‐stoichiometric UO_2+x is beneficial for sintering due to enhanced U ion diffusion from excessive O ion interstitials. The activation energies of the grain growth for UO_2.03 and UO_2.11 are determined as ~1.0 and ~2.0 eV, respectively. As compared with the micrometer‐sized UO₂ in which volumetric diffusion dominates the grain coarsening with an activation energy of ~3.0 eV, the enhanced grain growth kinetics in nano‐sized UO_2+x suggests that grain boundary diffusion controls grain growth. The higher activation energy of more hyper‐stoichiometric nano‐sized UO_2.11 may be attributed to the excessive O interstitials pinning grain boundary migration.     

Blown film extrusion of poly(lactic acid) without melt strength enhancers

Processing strategies were developed to manufacture poly(lactic acid) (PLA) blown films without melt strength enhancers (MSEs). The effects of processing temperature on PLA's melt properties (shear and elongational viscosities), PLA grades, and other processing conditions [ratio of take‐up roller to extruder's rotational screw speeds or processing speed ratio (PSR) and internal air pressures] on film's blow‐up ratio were examined. Experimental results indicate that extrusion‐blown amorphous and semicrystalline PLA films can be successfully manufactured without MSEs by controlling melt rheology through processing temperature and other extrusion processing conditions. PLA processed at lower extrusion temperature had higher melt viscosities, which favored the formation of stable films depending on the PSR and internal air pressure used. Inappropriate control of PSR and internal air pressure led to unstable films with various processing defects such as melt sag, bubble dancing, or draw resonance, irrespective of the lower extrusion processing temperature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45212.     

Effect of annealing temperature and $$\hbox {CdCl}_{2}$$ treatment on the photo-conversion efficiency of $$\hbox {CdTe/Zn}_{0.1}$$CdTe/Zn0.1$$\hbox {Cd}_{0.9}$$Cd0.9S thin film solar cells

We report the effects of annealing in conjunction with \(\hbox {CdCl}_{2}\) treatment on the photovoltaic properties of \(\hbox {CdTe/Zn}_{0.1}\hbox {Cd}_{0.9}\)S thin film solar cells. CdTe layer is subjected to dry \(\hbox {CdCl}_{2}\) treatment by thermal evaporation method and subsequently, heat treated in air using a tube furnace from 400 to \(500{^{\circ }}\hbox {C}\). AFM and XRD results show improved grain size and crystallographic properties of the CdTe film with dry \(\hbox {CdCl}_{2}\) treatment. This recrystallization and grain growth of the CdTe layer upon \(\hbox {CdCl}_{2}\) treatment translates into improved photo-conversion efficiencies of \(\hbox {CdTe/Zn}_{0.1}\hbox {Cd}_{0.9}\)S cell. The results of dry \(\hbox {CdCl}_{2}\) treatment were compared with conventional wet \(\hbox {CdCl}_{2}\) treatment. Photo-conversion efficiency of 5.2% is achieved for dry \(\hbox {CdCl}_{2}\)-treated cells in comparison with 2.4% of wet-treated cell at heat treatment temperature of \(425{^{\circ }}\hbox {C}\).     

Effect of banana peel powder on bioactive constituents and microstructural quality of chapatti: unleavened Indian flat bread

Effect of banana peel powder (BPP) on the bioactive constituents and micro structural quality of chapatti was evaluated. Chapatti dough prepared from 5, 10, 15 and 20 % BPP was examined for dough stickiness, dough strength, dough kneading and rollability. With increased level of BPP, there was an increase in subjective score in kneading and rollability of chapatti. Dough stickiness was increased while increased dough strength was observed with increased level of BPP. Chapatti incorporated with BPP showed total phenolic content and flavonoid content significantly higher than the control. Chapatti incorporated with 20 % BPP showed DPPH radical scavenging activity up to 68.3 %. The tear force of chapatti prepared from dough added with 5, 10, 15 and 20 % BPP was 414, 404, 393, 356.2 g which was lower than that of control (449 g). The microstructure of chapatti prepared from dough added with 15 % BPP was uniform with solubilised starch granules while in the control starch granules were overlapping on one another to form aggregation. The X-ray diffraction pattern for chapatti incorporated with 15 % BPP showed V-type pattern. Chapatti’s prepared from BPP had softer chapatti and better pliability.     

Compatibility and biodegradability of PMMA–starch cinnamate blends in various solvents

The compatibility of PMMA and starch cinnamate (STCN) blends prepared in tetrahydrofuran, 1,4‐dioxane, and N,N‐dimethylformamide has been examined through viscometry at 30°C. From the intrinsic viscosity, relative viscosity, reduced viscosity, and density measurements, the blends of the two polymers were observed to be compatible in all three solvents. The compatibility of the blends was also confirmed through FTIR and SEM studies. The blends were observed to be compatible on the basis of heat of mixing, but they were observed to be incompatible on the basis of polymer–polymer interaction parameters. Results obtained show that the compatibility predicted on the basis of viscometric and density measurements is not affected by the choice of solvents. Biodegradation studies showed 13% weight loss within 120 days in the case of the blend containing 30% STCN. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 488–496, 2001     

Self-assembly of the Ag deposited ZnO/carbon nanospheres: A resourceful photocatalyst for efficient photocatalytic degradation of methylene blue dye in water

Carbon nanospheres (CNSs) are synthesized by pyrolysis of benzene at 1000?°C. Various UV-light photocatalysts of ZnO/CNSs and Ag-ZnO/CNSs (AZCN) composites are synthesized on the surface of CNSs using a facile chemical precipitation method. Morphological and optical properties of the as-synthesized photocatalysts are characterized by scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, UV-Vis spectroscopy, photoluminescence and Raman spectroscopy. Photocatalytic degradation efficiency of methylene blue dye is investigated to examine the photocatalytic activity of synthesized photocatalysts. It is found that as-synthesized ZnO/CNSs composite can degrade higher methylene blue dye (～85.6%) after 25?min of UV irradiation in comparison with that of CNSs. A prominent improvement in the photodegradation is attained by depositing metal (Ag) particles on the surface of ZnO/CNSs composite. AZCN composite displays the enhanced photocatalytic degradation performance (～95% after 15?min of UV light) in high concentration of methylene blue dye. Furthermore, stability performance is studied by recycling the AZCN composite photocatalyst. It is found that the photocatalytic activity of AZCN composite is only slightly decreased even after five cycles. Present work demonstrates that AZCN composite show a great potential in the treatment of organic pollutants for wastewater treatment.     

Traversing the advantageous role of samarium doped spinel nanoferrites for photocatalytic removal of organic pollutants

The present work reportes the pertinence of samarium(Sm) doped spinel nanoferrites as magnetically recoverable photocatalyst for the removal of organic pollutants from wastewater.Thus,a series of Sm substituted spinel nano ferrites,MSm_xFe_(2-x)O_4(M=Ni,Co;x=0,0.02,0.06,0.1) we re synthesized via sol-gel methodology.The effect of Sm doping on the structural,morphological,optical and magnetic properties of pristine nanoferrites was investigated systematically.Further,the fabricated samples were explored as photocatalysts for the oxidative degradation of antibiotics(ofloxacin and norfloxacin) and dyes(methyl orange and safranin O).The Sm doped nanoferrites exhibit astonishing catalytic efficacy that can be attributed to higher surface area,octahedral site preference of Sm ions and reduced band gap.The synthesized nanoferrites display excellent recyclability which enables them to be utilized as potential photocatalysts for wastewater treatment.     

Compartmentalization Role of A-Kinase Anchoring Proteins (AKAPs) in Mediating Protein Kinase A (PKA) Signaling and Cardiomyocyte Hypertrophy

The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure–function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.