Search

• The FER with nano-sized fins was successfully prepared by a secondary growth method. • The finned FER shows more BASs and shorter diffusion pathway. • Both increased BASs and improved diffusion properties contribute to the enhanced DME carbonylation activity. The carbonylation of dimethyl ether (DME) to produce methyl acetate (MA) has a promising prospect in industry. FER zeolites have high MA selectivity and considerable stability but suffer from low activity due to diffusion limitation. Enhancing the diffusion properties of FER zeolites can improve their competitiveness in the DME carbonylation. This study proposed the synthesis of finned FER zeolites with low Si/Al ratio by a secondary growth method. Based on NH 3 -TPD and FTIR, the amount and distribution of acid sites in FER with fins were determined. Combining the normalized MA formation rates on the BASs in 8-MR and diffusion kinetic studies of DME, the influence of diffusion limitation was quantitatively discussed. The results showed that the acidity and diffusion properties were significantly improved on the finned FER, which boosted the DME conversion. This work illustrated the importance of the acidity and diffusion properties in FER catalyzed DME carbonylation. It inspires the rational design of zeolite catalysts by constructing morphology and optimizing compositions. [ABSTRACT FROM AUTHOR]

• As F-S powder content increases, the flexural crack spacing increases. • F-S concrete strength is an important factor ensuring the flexural capacity. • Concrete strength affects the ductility of RC beams. • F-S concrete with required strength can be applied in beams. Concrete containing ferronickel slag with blast furnace slag, namely composite ferronickel slag concrete or F-S concrete, is featured by low bond strength with horizontally-placed rebar compared with normal concrete of equal strength. This feature may affect the flexural capacity and deformational characteristic of F-S concrete beams, which needs to be investigated. Four under-reinforced beams were prepared and tested, including one normal concrete beam and three F-S concrete beams. The variable was the percentages of F-S powder content, i.e., 0%, 20%, 30%, and 40%. The experimental results showed that as F-S powder content increased, both the flexural capacity and ductility of RC beams decreased. For the flexural capacity analysis, directly increasing F-S powder content lowers concrete strength, thus reducing the flexural capacity. Regarding the deformational characteristic analysis, the RC beam is ideally simplified to the combination of the compressive concrete column model plus the tie bar model, and the influence of tensile rigidity effect with different bond level on the tie bar deformation is mainly studied. It is found that the lower bond stress just increases the flexural crack spacing, and changes the stress and strain distribution of rebar and concrete, but does not change the stress-mean strain relation of the rebar in the tie bar per unit length. The incorporation of F-S powder has no effect on the deformation of RC beams. Unexpectedly, the concrete strength is another important factor affecting the plastic rotation ability of RC beams. Whether increasing/decreasing the concrete strength will increase or decrease the ductility of RC beams, it is much determined by the given ratio of the longitudinal tensile reinforcement. In other words, while F-S concrete strength equals that of normal concrete, the ductility of the F-S concrete beam resembles that of normal concrete beam. F-S concrete can be applied in engineering structures, as long as it meets the design strength requirement as normal concrete does, irrespective of any F-S powder content. [ABSTRACT FROM AUTHOR]

Abstract: Neuronal injury in manganism is accompanied by activation of astroglia within the basal ganglia that is thought to increase production of inflammatory mediators such as nitric oxide (NO). The present studies postulated that astroglial-derived NO mediates neuronal apoptosis induced by manganese (Mn) and pro-inflammatory cytokines. Pheochromocytoma (PC12) cells differentiated with nerve growth factor (NGF) were co-cultured with primary astrocytes and exposed to Mn and tumor necrosis factor-α (TNF-α) plus interferon-γ (IFN-γ). Mn enhanced cytokine-induced expression of inducible nitric oxide synthase (NOS2, EC 1.14.13.39) and production of NO in astrocytes that correlated with apoptosis in co-cultured neurons, as determined by caspase activity, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL), and nuclear morphology. Apoptosis in PC12 neurons required the presence of astrocytes and was blocked by overexpression of a phosphorylation-deficient mutant of IκBα (S32/36A) in astrocytes that prevented induction of NOS2. Pharmacologic inhibition of NOS2 with (±)-2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) significantly reduced neuronal apoptosis, and the addition of low concentrations of the NO donor, S-nitroso-N-acetylpenicillamine (SNAP), to neurons cultured without astrocytes was sufficient to recover the apoptotic phenotype following exposure to Mn and TNF-α/IFN-γ. It is concluded that Mn- and cytokine-dependent apoptosis in PC12 neurons requires astroglial-derived NO and NF-κB-dependent expression of NOS2. [Copyright &y& Elsevier]

• Bond quality of F-S concrete is inferior to that of normal concrete. • Bleeding has a severe impact on the bond quality of reinforcement-concrete. • A bond stress-slip relationship was proposed for F-S concrete. • An anchorage length modifying factor was proposed for F-S concrete. Thirty-six pullout tests, including twelve groups of three specimens, were performed to study the bond behavior of steel reinforcement in concrete containing ferronickel slag and blast furnace slag powder (F-S powder/concrete). Test parameters considered in this research were F-S powder replacement percentages (i.e., 0%, 10%, 20%, 30%, 40%, and 50%) and concrete strength grades (i.e., C30 and C35). Unexpectedly, the results showed that the bond quality of steel reinforcement in F-S concrete was inferior to that of normal concrete even with comparable concrete strength. The more F-S powder content, the greater the inferiority. Through investigating the underlying mechanism, it was found that bleeding adversely affected the reinforcement-concrete bond quality in F-S concrete. Based on the pullout test results, a bond stress-slip relationship and an anchorage length modifying factor were proposed for F-S concrete of C30 and C35 strength grade. The conclusions would help designers assess the suitability of a particular F-S concrete for use in a given structure. [ABSTRACT FROM AUTHOR]

• F-S concrete presents identical mechanical properties to conventional concrete. • The stress-strain curve characteristics were mainly related to F-S concrete strength. • The stress-strain constitutive equations were established for F-S concrete. This study investigated the mechanical properties of concrete of strength grade C30 and C35, containing different content (10%–50%) of a composite admixture of ferronickel slag and blast furnace slag powder (referred to as F-S powder and F-S concrete hereafter, respectively). The mechanical properties include axial compressive strength, elastic modulus, Poisson's ratio, splitting tensile strength, and the compressive stress-strain relationship. The difference in mechanical properties between F-S concrete and conventional concrete was analyzed. Test results indicated that the positive correlation of conventional concrete between the axial compressive strength, elastic modulus, splitting tensile strength, and cubic compressive strength was applicable to F-S concrete irresponsible of the specific F-S powder content. Both Poisson's ratio and the failure mode under compression for F-S concrete were identical to those of conventional concrete. The shape characteristics and fitting parameters of the stress-strain curve were mainly related to F-S concrete strength grade but had little connection with the specific F-S powder content. Furthermore, based on tested data, the stress-strain constitutive equations were established for F-S concrete, which provides a reference for the test analysis of large specimens and corresponding engineering application. [ABSTRACT FROM AUTHOR]

In this work, a novel sustained released system (VCSB-Zn(II)) for zinc supplements was built by vanillin-chitosan Schiff base (VCSB) chelated with Zn2+ to improve the zinc trace element utilization ratio. Samples were characterized by FT-IR, 1H NMR, XRD, SEM, and TGA. The results showed that VCSB exhibited a more excellent chelation capacity of Zn2+ than chitosan. The chelation capacity of VCSB was about 1.7 times more than that of chitosan, corresponding to 50.96 mg/g and 29.91 mg/g, respectively. Furthermore, VCSB-Zn(II) showed excellent sustained released performance at simulated gastric fluid because of the acid slow-dissolving ability. And the higher the C N content of VCSB, the higher the cumulative release rate (R i) of Zn2+, the highest R i reached 77.81%. The sustained released curves were described by the first-order and Korsmeyer-Peppas equation, which described the Zn2+ sustained released performance caused by the dissolution of VCSB-Zn(II) and Fick diffusion. This Zn2+ sustained released system shows great potential in the application in the field of trace elements supplements for animals. [Display omitted] • Vanillin-chitosan Schiff base shows a higher chelation capacity of Zn2+ than chitosan. • Vanillin-chitosan Schiff base zinc complex was built for zinc supplements as a novel Zn2+ sustained release system. • The acid slow-dissolving ability of chitosan achieved Zn2+ sustained release in simulated gastric fluid. [ABSTRACT FROM AUTHOR]

Neuronal injury in manganese neurotoxicity (manganism) is thought to involve activation of astroglial cells and subsequent overproduction of nitric oxide (NO) by inducible nitric oxide synthase (NOS2). Manganese (Mn) enhances the effects of proinflammatory cytokines on expression of NOS2 but the molecular basis for this effect has not been established. It was postulated in the present studies that Mn enhances expression of NOS2 through the cis-acting factor, nuclear factor kappaB (NF-κB). Exposure of C6 glioma cells to lipopopolysaccharide (LPS) resulted in increased expression of NOS2 and production of NO that was dramatically potentiated by Mn and was blocked through overexpression of mutant IκBα (S32/36A). LPS-induced DNA binding of p65/p50 was similarly enhanced by Mn and was decreased by mutant IκBα. Phosphorylation of IκBα was potentiated by Mn and LPS and was not blocked by U0126, a selective inhibitor of ERK1/2. Mn decreased mitochondrial membrane potential and increased matrix calcium, associated with a rise in intracellular reactive oxygen species (ROS) that was attenuated by the mitochondrial-specific antioxidant, MitoQ. Blocking mitochondrial ROS also attenuated the enhancing effect of Mn on LPS-induced phosphorylation of IκBα and expression of NOS2, suggesting a link between Mn-induced mitochondrial dysfunction and activation of NF-κB. Overexpression of a dominant-negative mutant of the NF-κB-interacting kinase (Nik) prevented enhancement of LPS-induced phosphorylation of IκBα by Mn. These data indicate that Mn augments LPS-induced expression of NOS2 in C6 cells by increasing mitochondrial ROS and activation of NF-κB. [Copyright &y& Elsevier]

• The effects of adding basalt fiber and polyethylene fiber on the dynamic compressive strength of concrete under dynamic loading. • Dynamic damage constitutive model describing the behavior of BPFRC under dynamic compressive loading. In order to enhance concrete's impact resistance, this study investigates the effects of single basalt fiber and basalt-polyethylene hybrid fiber on concrete through split Hopkinson pressure bar (SHPB) tests, emphasizing their significance in engineering applications. A comparative analysis of the failure modes, dynamic compressive strength, dynamic compressive toughness, and dynamic growth factor of specimens was conducted under different strain rates and polyethylene fiber volume fractions. The study considered concrete damage, strain rate effect, and the toughening effect of fibers, introducing the damage factor, and establishing a dynamic damage constitutive model for fiber-reinforced concrete. The results showed that basalt-polyethylene fiber reinforced concrete (BPFRC) exhibited better impact resistance and deformation capability. There were improvements observed in dynamic compressive strength, dynamic compressive toughness, and dynamic growth factor. The addition of basalt fiber (BF) and polyethylene fiber (PE) played a buffering role in inhibiting crack propagation and slowing down the damage process. The optimum PE volume fraction for dynamic compressive strength was 0.1% at a strain rate of 60 s−1, 0.15% at a strain rate of 95 s−1, and 0.05% at a strain rate of 120 s−1, all with a BF volume fraction of 0.25%. The optimum fiber volume fractions for dynamic compressive toughness and dynamic peak toughness were consistent, both at 0.25% BF and 0.1% PE. The established dynamic damage constitutive model for fiber-reinforced concrete can effectively describe the impact resistance performance of BPFRC, and the experimental curves fit well with the constitutive curves. Furthermore, it was observed that BF acted as macrofibers, bridging to restrain the post-hardening cracking of concrete, while PE acted as microfibers, inhibiting the propagation of plastic cracks, reducing internal defects in concrete, and enhancing the ductility and toughness of concrete. Consequently, BPFRC holds significant potential value in engineering applications. [ABSTRACT FROM AUTHOR]