Plastic deformation of dense nanocrystalline yttrium oxide at elevated temperatures

Nanocrystalline yttrium oxide, Y₂O₃ with 110 nm average grain size was plastically deformed between 800 °C and 1100 °C by compression at different strain rates and by creep at different stresses. The onset temperature for plasticity was at 1000 °C. Yield stress was strongly temperature dependent and the strain hardening disappeared at 1100 °C. The polyhedral and equiaxed grain morphology were preserved in the deformed specimens. The experimentally measured and theoretically calculated stress exponent n = 2 was consistent with the plastic deformation by grain boundary sliding. Decrease in the grain size was consistent with decrease in the brittle to ductile transition temperature.     

Characterisation of the Dynamic Interactions between Complex N-Glycans and Human CD22

CD22 (Siglec-2) is a B-cell surface inhibitory protein capable of selectively recognising sialylated glycans, thus dampening autoimmune responses against self-antigens. Here we have characterised the dynamic recognition of complex-type N-glycans by human CD22 by means of orthogonal approaches including NMR spectroscopy, computational methods and biophysical assays. We provide new molecular insights into the binding mode of sialoglycans in complex with h-CD22, highlighting the role of the sialic acid galactose moieties in the recognition process, elucidating the conformational behaviour of complex-type N-glycans bound to Siglec-2 and dissecting the formation of CD22 homo-oligomers on the B-cell surface. Our results could enable the development of additional therapeutics capable of modulating the activity of h-CD22 in autoimmune diseases and malignancies derived from B-cells.     

Synthesis of magnetic nanocomposite microparticles for binding of chlorinated organics in contaminated water sources

In this work, the development of novel magnetic nanocomposite microparticles (MNMs) via free radical polymerization for their application in the remediation of contaminated water is presented. Acrylated plant-based polyphenols, curcumin multiacrylate (CMA) and quercetin multiacrylate (QMA), were incorporated as functional monomers to create high affinity binding sites for the capture of polychlorinated biphenyls (PCBs), as a model pollutant. The MNMs were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, dynamic light scattering, and UV–visible spectroscopy. The affinity of these novel materials for PCB 126 was evaluated and fitted to the nonlinear Langmuir model to determine binding affinities (K_D). The results suggest the presence of the polyphenolic moieties enhances the binding affinity for PCB 126, with K_D values comparable to that of antibodies. This demonstrates that these nanocomposite materials have promising potential as environmental remediation adsorbents for harmful contaminants.     

Design, synthesis, and biological evaluation of 2-aminobenzanilide derivatives as potent and selective HDAC inhibitors

Epigenetic regulation is an essential process for the normal functioning of genes. Therefore, targeting epigenetic dysregulation in cancer may be a valid therapeutic approach for the treatment of this severe disease. Histone deacetylases (HDACs) are enzymes involved in the regulation of epigenetic post-translational modifications; because they are overexpressed in many types of cancer, HDACs are valuable targets for the development of new anticancer agents. A large series of 2-aminobenzanilides linked at the 4'-position to α-amino acid amides, arenes, and heteroarenes through a methylene bridge were designed, synthesized, and tested as novel HDAC inhibitors. Several compounds showed IC(50) values in the two-digit nanomolar range in hrHDAC1 inhibition assays, lower than that of the reference compound MS-275. They also showed interesting selectivity profiles, as confirmed by western blot assays.     

Virus-templated iridium oxide-gold hybrid nanowires for electrochromic application

A highly porous electrode comprised of biologically templated iridium oxide-gold (IrO(2)-Au) hybrid nanowires is introduced for electrochromic applications. A filamentous M13 virus is genetically engineered to display IrO(2)-binding peptides on the viral surface and used as a template for the self-assembly of IrO(2) nanoclusters into a nanowire. The open porous morphology of the prepared nanowire film facilitates ion transport. Subsequently, the redox kinetics of the IrO(2) nanowires seems to be limited by the electric resistance of the nanowire film. To increase the electron mobility in the nanowires, gold nanoparticles are chemically linked to the virus prior to the IrO(2) mineralization, forming a gold nanostring structure along the long axis of the virus. The resulting IrO(2)-Au hybrid nanowires exhibit a switching time of 35 ms for coloration and 25 ms for bleaching with a transmission change of about 30.5% at 425 nm. These values represent almost an order of magnitude faster switching responses than those of an IrO(2) nanowire film having the similar optical contrast. This work shows that genetically engineered viruses can serve as versatile templates to co-assemble multiple functional molecules, enabling control of the electrochemical properties of nanomaterials.     

Appraisal of ε-Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

The potential of ε-caprolactam (CAP) and trimellitic anhydride (TMA) compounds as novel chain extenders for poly(lactic acid) (PLA) has been assessed; the amounts of 0.01, 0.025, and 0.05 wt% each additive have been added. The chain extension was evidenced by the increase in PLA/CAP and PLA/TMA viscosities in mixing torque measurements and by infrared spectroscopy. PLA reaction with CAP and TMA has also been confirmed from contact angle and surface free energy studies, which have shown that the increase in TMA amount decreased the hydrophilicity of PLA due to the decreased concentration of terminal surface hydroxyl groups. However, the addition of CAP accentuated the PLA hydrophilicity as indicated by the increase in the polar component of the surface energy. On the other hand, the glass transition temperature of PLA/TMA and PLA/CAP decreased as a result of a local plasticizing effect, which favored the chain mobility and the crystallization of PLA due to the concomitant nucleating effect of the chain extenders moieties too. Furthermore, the higher molecular weight of PLA/CAP and PLA/TMA was responsible for their increased thermal stability and higher impact strength with respect to PLA. POLYM. ENG. SCI., 60:944–955, 2020. © 2020 Society of Plastics Engineers     

Lithium fuel cells:: I. Lithium/poly(organophosphazene) membrane anodes in KOH and seawater

The main goal of our research project is to design safe, high energy and power density lithium/water systems. We explored the feasibility of substituting the natural bilayer (formed on the lithium surface when lithium is in contact with water), for a thin polymeric film. By substituting the natural bilayer film we hope to reduce the parasitic reactions occurring at the lithium/water interface, thus yielding an increase in the anodic efficiency. We investigated the effect of placing or casting a thin, (lithium/ion-conducting) polymer layer on the lithium metal surface. This paper is part one in a series of two papers. Paper I presents the results obtained with a lithium/polymer system, where the polymer was a monolayer of a polyphosphazene with 90% trifluoromethylphenoxy and 10% lithium carboxyphenoxy side groups (Polymer 4), or a multilayer film formed of one layer of poly[bis(methoxyethoxyethoxy)phosphazene] (MEEP) and one to three layers of Polymer 4 containing from 0 to 75 wt.% of lithium triflate salts. Paper II presents results obtained when the polymer layers were prepared using a polymer with equal amounts of methoxyethoxyethoxy and phenoxy side groups containing from 0 to 75 wt.% of lithium triflate salts. Phosphazene membranes have been designed and tailored to allow lithium ion conduction and prevent water migration to the surface of lithium metal. The phosphazene membranes enhance the safety of an aqueous lithium cell by inhibiting (or reducing) the reaction of lithium with water that evolves hydrogen at the anode. Original tests of lithium/phosphazene systems led to unpredictable open circuit voltages (OCVs). When the adhesion of the membrane to the lithium metal was improved, the OCV stabilized. The OCVs for the half-cell of lithium polymer aqueous electrolytes varies between −3.1 and −2.8 V_SCE, depending on the membrane. The current densities for this polymer system are in the range of 10⁻⁶-10⁻³ A/cm². The Columbic anodic efficiency is assumed to be near 100%—as hydrogen evolution is not measurable. Some of the polymeric membranes developed pinholes with use. Layered systems have also been designed to avoid the development of pinholes over time. In this paper, we present the results obtained by using polyphosphazenes with a 9:1 ratio of trifluoromethylphenoxy and p-carboxyphenoxy side groups and the lithium salt of the carboxylate function. Poly(organophosphazene) membranes with a single layer and a multilayer structure were tested in 8 M KOH or synthetic seawater for up to 5 days.     

Solid Yttria-Stabilized Zirconia Films by Pulsed Chemical Vapor Deposition from Metal-organic Precursors

A pulsed chemical vapor deposition from metal-organic precursors (MOCVD) system was used to produce solid zirconia, and yttria-stabilized zirconia (YSZ) films. A total of six candidate metal-organic precursors for zirconia and three for yttria were investigated. Three precursor solutions for YSZ proved suitable for pulsed-MOCVD processing. Layers were deposited on metal, alumina, and porous nickel cermet substrates. Under optimal deposition conditions, precursor conversion efficiency of 90% was achieved using a solution of 3.74 vol% zirconium 2-methyl-2-butoxide + 0.42% yttium methoxyethoxide in toluene. The film growth rate was 7.5 μm·h⁻¹ at 525°C deposition temperature. Two alkoxide precursors produced YSZ layers with material costs under $0.50/(μm·cm²).     

Influence of dietary long-chain PUFA on premature baboon lung FA and dipalmitoyl PC composition

One of the major survival challenges of premature birth is production of lung surfactant. The lipid component of surfactant, dipalmitoyl PC (DPPC), increases in concentration in the period before normal term birth via a net shift in FA composition away from unsaturates. We investigated the influence of dietary DHA and arachidonic acid (AA) on lung FA composition and DPPC concentration in term and preterm baboons. Pregnant animals/neonates were randomized to one of four groups: breast-fed (B), term formula-fed (T⁻), preterm formulafed (P⁻), and preterm fed formula supplemented with DHA-AA (P⁺). Breast milk contained 0.68%wt DHA and the P⁺ group formula contained 0.61%wt DHA. In the preterm groups (P⁻ and P⁺), pregnant females received a course of antenatal corticosteroids. At the adjusted age of 4 wk, neonate lung tissue was harvested, and FA composition and DPPC were analyzed. Palmitate was ∼28%wt of lung total FA and no significant differences were found among the four treatment groups. In contrast, DPPC in the B group lung tissue was significantly greater than DPPC in the unsupplemented groups, but not compared with the P⁺ group. The B and P⁺ groups were not significantly different in DHA and AA, but were different compared with the unsupplemented (T, P⁻) groups. These results indicate that LCP supplementation increases lung DHA and AA, without compromising overall lung 16∶0 or DPPC. The shift in FA composition toward greater unsaturation in the groups consuming LCP supported improved surfactant lipid concentration in preterm neonate lungs.