Microstructure and electrical conductivity of Mo/TiN composite powder for alkali metal thermal to electric converter electrodes

A Mo/TiN composite powder has been synthesized by a sol–gel method to improve the electrical performance and microstructural stability of the alkali metal thermal to electric converter electrode. The core (TiN)–shell (Mo) structure of the composite powder is confirmed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. The composite powder is primarily composed of submicron (400–800 nm) particles that are coated on a core (>3–5 μm) particle. The Mo/TiN composite electrode exhibits high electrical conductivities of 1000 Scm⁻¹ at 300 °C and 260 Scm⁻¹ at 700  °C in an Ar atmosphere. The electrode exhibits excellent tolerance against grain growth during thermal cycling tests (R.T.↔800 °C), where the average growth rate of Mo grains in the Mo/TiN composite electrodes is controlled less than 0.5%/time (0.62→0.65 μm), while the growth rate in Mo electrodes is 306.7%/time (0.24→3.92 μm). It can be concluded that the Mo/TiN composite powder will suppress the degradation of the electrode and enhance the performance and durability of the unit cell at elevated temperatures.     

Sonochemical Synthesis and Characterization of A Nano-Rod Lead(II) Supramolecular, Three Dimensional Coordination Compound: New Precursor to Produce Pure Phase Nano-Sized Lead(II) Oxide

Nanorods of a lead(II) supramolecular three-dimensional (3D) coordination compound, [Pb(tfpb)₂]_n (1) (Htfpb?=?4,4,4-trifluoro-1-phenyl-1,3-butanedione), was prepared by the sonochemical method. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. A single-crystal structure of the compound showed that the coordination number of Pb(II) is eight with six O-donor atoms from the tfpb ligand and two F-donors from anionic ligands. The 3D supramolecular structure of 1 is realized by weak directional C–F···F–C and π–π stacking interactions. After calcination of nano-sized 1 at 500?°C, pure phase nano-sized lead(II) oxide is produced.     

Solvothermal Synthesis of a Nano-sized Aza-aromatic Base Adduct of a Cadmium(II) 4,4-Difluoro-1-phenyl-1,3-butandionate Coordination Compound

A new nano-structured cadmium(II) coordination compound, [Cd(phen)(dfpb)₂] (1) (phen?=?1,10-phenanthroline, dfpb?=?4,4-difluoro-1-phenyl-1,3-butandion), was synthesized by a solvothermal method and produced a coordination polymer in the nano-size range. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction elemental analysis and IR spectroscopy. Compound 1 was structurally characterised by single crystal X-ray diffraction. The single crystal structure shows a coordination number for the Cd ion of six with two N-donor atoms from the phen ligand and four O-donors from the two dfpb moieties. Self-assembly occurs by CH····F–C and π–π stacking interactions. The supramolecular features in these complexes are controlled by weak directional intermolecular interactions.     

Enhanced mechanical properties and pre-tension effects of polyurethane (PU) nanofiber filaments prepared by electrospinning and dry twisting

We studied the mechanical properties of polyurethane (PU) nanofiber filaments prepared by electrospinning and dry twisting, and compared them with those of the corresponding nonwoven PU nanofiber webs. The morphologies and mechanical properties of the nonwoven PU nanofiber webs and the corresponding PU nanofiber filaments were investigated by scanning electron microscopy (SEM) and through the use of a universal testing machine (UTM), respectively. The tensile strength and the Young’s modulus of the nanofiber filaments improved dramatically as the number of twists or the width of the nanofiber webs was increased compared with the nonwoven PU nanofibers. Moreover, it was found that applying pre-tension was an effective method of increasing the mechanical properties of PU nanofiber filaments.     

Influence of Y2O3 addition on electrical properties of β-SiC ceramics sintered in nitrogen atmosphere

The influence of Y₂O₃ addition on electrical properties of β-SiC ceramics has been investigated. Polycrystalline SiC samples obtained by hot-pressing SiC–Y₂O₃ powder mixtures in nitrogen (N) atmosphere contain Y₂O₃ clusters segregated between SiC grains. Y₂O₃ forms a Y–Si-oxycarbonitride phase during sintering by reacting with SiO₂ and SiC and by dissolution of N from the atmosphere; this induces N doping into the SiC grains during the process of grain growth. The SiC samples exhibit an electrical resistivity of ～10^?3 Ω cm and a carrier density of ～10²⁰ cm^?3, which are ascribed to donor states derived from N impurities. The increase in defect density with increasing Y₂O₃ content is likely to be a main limiting factor of the electrical conductivity of SiC ceramics.     

Effect of grain size on the mechanical properties and crack formation of HPFRCC containing deformed steel fibers

This research investigated the influence of sand grain size on the behavior of high-performance fiber-reinforced cementitious composites (HPFRCC). Four types of sand with different grain sizes were investigated using the same matrix composition containing 2.0% hooked and twisted fibers by volume. The compressive strength was significantly greater for the finer sand grains, despite little difference in the packing density. The better compressive strength was mainly due to the denser calcium silicate hydrate (CSH) resulting from an intensive pozzolanic reaction with the finer silica sand, rather than to an improvement in packing density. The interfacial bond strength of those fibers was notably improved, having favorable effects on the mechanical properties and multiple crack formation of HPFRCCs. Although both fibers showed superior properties in mortars with a finer sand grain, twisted fiber produced more sensitive behavior according to the sand grain size.     

Prunella vulgaris Suppresses HG-Induced Vascular Inflammation via Nrf2/HO-1/eNOS Activation

Vascular inflammation is an important factor which can promote diabetic complications. In this study, the inhibitory effects of aqueous extract from Prunella vulgaris (APV) on high glucose (HG)-induced expression of cell adhesion molecules in human umbilical vein endothelial cells (HUVEC) are reported. APV decreased HG-induced expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. APV also dose-dependently inhibited HG-induced adhesion of HL-60 monocytic cells. APV suppressed p65 NF-κB activation in HG-treated cells. APV significantly inhibited the formation of intracellular reactive oxygen species (ROS). HG-stimulated HUVEC secreted gelatinases, however, APV inhibited it. APV induced Akt phosphorylation as well as activation of heme oxygenase-1 (HO-1), eNOS, and nuclear factor E2-related factor 2 (Nrf2), which may protect vascular inflammation caused by HG. In conclusion, APV exerts anti-inflammatory effect via inhibition of ROS/NF-κB pathway by inducing HO-1 and eNOS expression mediated by Nrf2, thereby suggesting that Prunella vulgaris may be a possible therapeutic approach to the inhibition of diabetic vascular diseases.     

Hepatoprotective Potency of Chrysophanol 8-O-Glucoside from Rheum palmatum L. against Hepatic Fibrosis via Regulation of the STAT3 Signaling Pathway

Rhubarb is a well-known herb worldwide and includes approximately 60 species of the Rheum genus. One of the representative plants is Rheum palmatum, which is prescribed as official rhubarb due to its pharmacological potential in the Korean and Chinese pharmacopoeia. In our bioactive screening, we found out that the EtOH extract of R. palmatum inhibited hepatic stellate cell (HSC) activation by transforming growth factor β1 (TGF-β1). Chemical investigation of the EtOH extract led to the isolation of chrysophanol 8-O-glucoside, which was determined by structural analysis using NMR spectroscopic techniques and electrospray ionization mass spectrometry (ESIMS). To elucidate the effects of chrysophanol 8-O-glucoside on HSC activation, activated LX-2 cells were treated for 48 h with chrysophanol 8-O-glucoside, and α-SMA and collagen, HSC activation markers, were measured by comparative quantitative real-time PCR (qPCR) and western blotting analysis. Chrysophanol 8-O-glucoside significantly inhibited the protein and mRNA expression of α-SMA and collagen compared with that in TGF-β1-treated LX-2 cells. Next, the expression of phosphorylated SMAD2 (p-SMAD2) and p-STAT3 was measured and the translocation of p-STAT3 to the nucleus was analyzed by western blotting analysis. The expression of p-SMAD2 and p-STAT3 showed that chrysophanol 8-O-glucoside strongly downregulated STAT3 phosphorylation by inhibiting the nuclear translocation of p-STAT3, which is an important mechanism in HSC activation. Moreover, chrysophanol 8-O-glucoside suppressed the expression of p-p38, not that of p-JNK or p-Erk, which can activate STAT3 phosphorylation and inhibit MMP2 expression, the downstream target of STAT3 signaling. These findings provided experimental evidence concerning the hepatoprotective effects of chrysophanol 8-O-glucoside against liver damage and revealed the molecular basis underlying its anti-fibrotic effects through the blocking of HSC activation.     

Formation of bed agglomeration in a fluidized multi-waste incinerator

A case study was carried out to investigate the bed agglomeration observed in a fluidized bed incinerator when burning blends of three wastes (carbon soot, biosludge and fuel oil). Several instrumental approaches were employed (i.e. XRF, SEM, XRD, and ICP-AES) to identify the bed materials (fresh sand and degrader sand) and clinkers formed in the full-scale incinerator tests. Several elements (V, Al, S, Na, Fe, Ni, P, and Cl), which normally are associated with the formation of low melting point compounds, were found in the waste blends at high content levels. The clinker bridges were identified to be associated with Al, Fe, V, K, Na, S, Ni, and Si elements.The effects of temperature and blending ratio were investigated in a muffle furnace. Carbon soot is believed to be more susceptible to the clinker formation than the other two fuels. Thermodynamic multi-phase multi-component equilibrium calculations predict that the main low melting point species could be Al₂(SO₄)₃, Fe₂(SO₄)₃, Na₂SO₄, NaCl, Na₂SiO₃ and V₂O₅. This information is useful to understand the chemistry of clinker formation. Also, it helps to develop methods for the control and possible elimination of the agglomeration problem for the design fuels.