4,283 research outputs found
Effects of the initial water curing time on the corrosion behavior of steel bar corrosion in fly ash concrete
AbstractConcrete specimens made of 30% fly ash (FA) replacement ratio and ordinary Portland cement (OPC) were fabricated to study the effects of the initial water curing time on the corrosion behavior of the embedded steel bar. The specimens were cured in water tank for 5days, 7days, 14days and 28days respectively at a normal temperature of 20□, then taken out and stored at an indoor natural environment. At the exposure time of 60days, 120days and 180days, steel bars' corrosion current densities icorr, corrosion potentials Ecorr in FA and OPC concrete specimens and their electrical resistivities ρc were tested. Results indicate that the initial wet curing time has important effects on steel bars' corrosion behaviors in both FA concrete and OPC concrete. With the increase of the initial wet curing time, steel bars' icorr all tend to decrease and Ecorr tend to increase. The longer the initial wet curing time, the higher the protective ability of FA concrete, compared to OPC concrete. Under the normal temperature, the shorter initial wet curing time of 5days and 7days for FA concrete showed worse protective ability than OPC concrete. However, when the initial wet curing time surpasses 14days, FA concrete behaves better than OPC concrete
Cinnamic aldehyde treatment alleviates chronic unexpected stress-induced depressive-like behaviors via targeting cyclooxygenase-2 in mid-aged rats
Ethnopharmacological relevance: COX-2 has been considered as a potent molecular target for prevention and therapy of depression. However, a recent study showed that COX-2 inhibitor does not improve depressive symptoms in persons aged 70 and over. Therefore, whether treatments targeting COX-2 have a clinical efficacy in depression, especially elderly individuals, remains unclear. Cinnamic aldehyde is a major constituent of Cinnamomum cassia, which has exhibited excellent anti-inflammatory activities as a COX-2 inhibitor. To investigate the potential antidepressant effect of cinnamic aldehyde in mid-aged rats
Correlating Gravitational Waves with -boson Mass, FIMP Dark Matter, and Majorana Seesaw Mechanism
We study a minimal extension of the Standard Model by introducing three
right-handed neutrinos and a new scotogenic scalar doublet, in which the mass
splittings between neutral and charged components are responsible for the
-boson mass newly measured by the CDF collaboration. This model can not only
generate non-vanishing Majorana neutrino masses via the interaction of
right-handed neutrinos and scotogenic scalars, but also explain the Universe's
missing matter in the form of FIMP dark matter. We also study the influence of
the mass splitting on the first order electroweak phase transition, and find
that it can further enhance the transition strength and thus induce
gravitational waves during the phase transition, which may be detected in the
forthcoming detectors such as U-DECIGO.Comment: References updated, accepted for publication in Science Bulleti
Proper Matter Collineations of Plane Symmetric Spacetimes
We investigate matter collineations of plane symmetric spacetimes when the
energy-momentum tensor is degenerate. There exists three interesting cases
where the group of matter collineations is finite-dimensional. The matter
collineations in these cases are either four, six or ten in which four are
isometries and the rest are proper.Comment: 10 pages, LaTex, accepted for publication in Modern Physics Letters
Di-μ-cyanido-1:2κ2 C:N,2:3κ2 N:C-hexacyanido-1κ3 C,3κ3 C-tetrakis(1,10-phenanthroline)-1κ2 N,N′;2κ4 N,N′;3κ2 N,N′-1,3-dicobalt(III)-2-iron(II) tetrahydrate
The hydrothermal reaction of CoCl2·6H2O, 1,10-phenanthroline (phen) and K3[Fe(CN)6] in deionized water yielded the title cyanide-bridged trinuclear cluster, [Co2Fe(CN)8(C12H8N2)4]·4H2O or [{CoIII(phen)(CN)4}2{FeII(phen)2}]·4H2O, which contains two CoIII centers and one FeII center linked by cyanide bridges. The combination of coordinative bonds, O—H⋯N and O—H⋯O hydrogen bonds and π–π stacking interactions [centroid–centroid distance = 3.630 (2) Å] results in the stabilization of a supramolecular structure. All uncoordinated water molecules are disordered. Thermogravimetric analysis reveals that the title complex loses the four crystal water molecules at about 333 K, then the anhydrous phase loses no further mass up to about 573 K, above which decomposition occurs
Production of copolyesters of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoates by E. coli containing an optimized PHA synthase gene
BACKGROUND: Microbial polyhydroxyalkanoates (PHA) are biopolyesters consisting of diverse monomers. PHA synthase PhaC2(Ps) cloned from Pseudomonas stutzeri 1317 is able to polymerize short-chain-length (scl) 3-hydroxybutyrate (3HB) monomers and medium-chain-length (mcl) 3-hydroxyalkanoates (3HA) with carbon chain lengths ranging from C6 to C12. However, the scl and mcl PHA production in Escherichia coli expressing PhaC2(Ps) is limited with very low PHA yield. RESULTS: To improve the production of PHA with a wide range of monomer compositions in E. coli, a series of optimization strategies were applied on the PHA synthase PhaC2(Ps). Codon optimization of the gene and mRNA stabilization with a hairpin structure were conducted and the function of the optimized PHA synthase was tested in E. coli. The transcript was more stable after the hairpin structure was introduced, and western blot analysis showed that both codon optimization and hairpin introduction increased the protein expression level. Compared with the wild type PhaC2(Ps), the optimized PhaC2(Ps) increased poly-3-hydroxybutyrate (PHB) production by approximately 16-fold to 30% of the cell dry weight. When grown on dodecanoate, the recombinant E. coli harboring the optimized gene phaC2(Ps)O with a hairpin structure in the 5’ untranslated region was able to synthesize 4-fold more PHA consisting of 3HB and medium-chain-length 3HA compared to the recombinant harboring the wild type phaC2(Ps). CONCLUSIONS: The levels of both PHB and scl-mcl PHA in E. coli were significantly increased by series of optimization strategies applied on PHA synthase PhaC2(Ps). These results indicate that strategies including codon optimization and mRNA stabilization are useful for heterologous PHA synthase expression and therefore enhance PHA production
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