Search

Background: The fruit of Psoralea corylifolia L., Psoraleae fructus (PF), is widely used in traditional Chinese medicine as a well-known herbal tonic. Previous studies have shown that PF and its major constituents may have potential values in the treatment of Parkinson and Alzheimer diseases, though their pharmacokinetics and brain distribution were largely unknown.Purpose: To develop a liquid chromatographic-tandem mass spectrometry (LC-MS/MS) method for simultaneous studies of the plasma pharmacokinetics and cerebral nuclei (including cerebellum, thalamus, brainstem, hippocampus, corpus striatum and cortex) distribution in rats of eleven known PF compounds following as psoralen, isopsoralen, psoralidin, bavachin, bavachinin, isobavachin, isobavachalcone, bavachalcone, neobavaisoflavone, corylifol A, and corylin.Methods: Rats were orally administered via gavage at a single dose of PF extract at 1.2 g/kg. The eleven known PF compounds were extracted from rat plasma and cerebral nuclei at different time points, and then determined by the established LC-MS/MS method. Non-compartmental pharmacokinetic profiles were calculated, and the distribution in rat plasma and cerebral nuclei were compared.Results: The results showed that all the tested compounds were quickly absorbed into rat plasma and distributed almost evenly to the cerebral nuclei. The distribution concentrations at different nuclei varied at one determined time point, but the overall trends were basically similar to the plasma concentration-time results. Psoralen and isopsoralen, the two highest coumarins contained in PF, displayed far higher plasma concentrations (AUC0→∞, plasma≈53,884∼65,578 ng·h/ml) and central nervous system penetration (AUC0→∞, brain nuclei ≈44,659∼65,823 ng·h/g) than the prenylflavonoids (other compounds except psoralidin, AUC0→∞, plasma≈69∼324 ng·h/ml; AUC0→∞, brain nuclei ≈119∼3662 ng·h/g). However, the total brain-to-plasma ratios of the prenylflavonoids were higher than the coumarins, suggesting the prenylflavonoids can more readily enter the brain than the coumarins.Conclusion: The established LC-MS/MS method is sensitive and specific for the simultaneous quantitation of the eleven PF compounds in rat plasma and cerebral nuclei. The results of plasma pharmacokinetics and cerebral nuclei distribution may reveal the possible substance basis for the CNS activities of PF, and highlight the application possibility of PF and its major constituents in the treatment of Parkinson and Alzheimer diseases. [ABSTRACT FROM AUTHOR]

Marine engineering structures may be subjected to various levels of vessel collisions, causing different degrees of damage to the RC piles. However, the influence of different combinations of impact mass and velocity under the same initial kinetic energy or momentum on the impact behavior of RC piles has not been explored. A numerical investigation of the impact responses of RC pile structures (including plumb piles and inclined pile groups) considering the material strain rate effect is carried out using the software ABAQUS/Explicit in this paper. Parametric studies are conducted based on the validated finite element models of RC piles subjected to horizontal impact. The internal force distributions, as well as the effect of the impact kinetic energy and the momentum (including different combinations of impact mass and initial velocity) on the impact response of RC piles, are discussed. The results indicate that the development path of the bending moment‒overall structural displacement curves in the plastic hinge regions of RC piles are almost identical under both impact and static loading conditions. Compared to momentum, the impact response of RC piles is insensitive to the variation of impact kinetic energy with different combinations of impact mass and velocity. Therefore, the impact kinetic energy is more suitable for evaluating the structural deformation of RC piles after impact. Finally, a performance-based impact-resistance design framework for RC piles is proposed. • A numerical investigation of the impact responses of RC pile structures is carried out. • The internal force distributions on the impact response of RC piles are discussed. • The effect of different combinations of impact mass and initial velocity on the response of RC piles is studied. • A performance-based impact-resistance design framework for RC piles is proposed. [ABSTRACT FROM AUTHOR]

Abstract This study assessed the environmental impacts of a composite polyvinylidene fluoride (PVDF) membrane (incorporating nanomaterials) and compared with neat PVDF membrane on algal membrane photoreactor (A-MPR) system's overall sustainability. The life cycle assessment (LCA) was carried out using Simapro 8.4.0 with cradle-to-gate approach, including raw materials, equipment, transportation and electricity consumption using ReCiPe 1.13 (H) and IPCC 2013 GWP 100a methodology. From the LCA analysis, silver/graphene oxide - polyvinylidene fluoride (Ag/GO-PVDF) membrane fabrication showed higher environmental impact than the neat PVDF membrane fabrication due to the addition of Ag/GO nanohybrids into the polymer. However, the A-MPR system using the Ag/GO-PVDF membrane exhibited better environmental footprint due to the improved performance of the modified membrane in producing higher volume of permeate as the output. Therefore, the A-MPR system using Ag/GO-PVDF membrane had outweighed the additional environmental impact of the Ag/GO-PVDF membrane fabrication process. Energy demand was identified as the main environmental hotspot in the LCA analysis. Subsequently, sensitivity analysis was performed to find out the effect of various energy mix for electricity generation towards the environment. The analysis revealed that the energy source for electricity generation had significant influence on the overall sustainability of the A-MPR system. The use of grid with 100% renewable energy (hydropower and geothermal) and solar photovoltaic might be able to mitigate 94.8% and 97.5% of CO 2 emission, respectively. Highlights • Fabrication of composite membrane had greater environmental influence. • Composite membrane showed lower environmental footprint in the reactor operation. • Reduction of electricity usage is essential to minimize the environmental impact. • Development of green energy source is crucial to reduce environmental loads. [ABSTRACT FROM AUTHOR]

Poor corrosion property has been a bottleneck problem during the application of Mg alloys. This work proposes a new way to improve the corrosion resistance of MgNd alloy by micro-alloying Zr, which promotes the precipitation process to rapidly form a protective corrosion layer. The corrosion rate decreases by three orders of magnitude from 32.69 mL/cm2/day to 0.072 mL/cm2/day. The results show Zr tends to form nano-scale oxide clusters on Mg surface, acting as pre-precipitation sites to accelerate the precipitation and facilitate the formation of dense and compact corrosion layer. [Display omitted] • Via micro-alloying Zr, the corrosion rate of Mg-Nd alloy decreases by three orders of magnitude to 0.072 mL/cm2/d. • The formation process of the corrosion layer was monitored and clarified by in-situ AFM and EN technique. • The oxide of Zr can act as pre-precipitate sits to accelerate the precipitation rate, leading to a dense and compact corrosion layer. [ABSTRACT FROM AUTHOR]

This study investigated the characteristics of various graphene oxide (GO) nanohybrid membranes and their performance in algal organic matter (AOM) filtration. The membranes were fabricated by phase inversion method. The effect of GO and its nanohybrids embedded in membranes was investigated in terms of wettability, porosity, pore size, surface charge, composition, morphology, permeability, fouling resistance and antimicrobial ability. In addition, the rejection of protein and carbohydrate as critical foulants in AOM was studied. Based on the findings, all the composite membranes showed lower flux decline than PVDF membrane. Composite membranes maintained higher protein (81–86%) and carbohydrate (77–83%) rejection compared with PVDF membrane (64% for protein and 63% for carbohydrate). However, the reversible to irreversible fouling ratio of PVDF, ZnO/GO-PVDF, Ag/GO-PVDF and GO-PVDF membranes was 3.07, 1.53, 0.86 and 1.09, respectively. This scenario implied that more hydrophilic substances in small molecular weight (MW) contained in AOM had plugged the composite membranes' pores and resulted in irreversible fouling. On the other hand, ZnO/GO-PVDF and Ag/GO-PVDF membranes exhibited superior antimicrobial ability and showed great potential in anti-biofouling mitigation. [ABSTRACT FROM AUTHOR]

Transition metal complexes capable of near-infrared light triggered-cytotoxicity are actively being developed as potential photosensitizers (PS) for photodynamic therapy (PDT) of cancers. In the present work, the structures and photophysical properties of complexes Pt(NˆCˆN)Cl and Pd(NˆCˆN)Cl (NˆCˆN = 2,6-dipyrido-4-methyl-benzenechloride) are investigated with a theoretical approach. The features of low-lying singlet and triplet excited states are discussed in detail. Their potential therapeutic use as two-photon PS in PDT is proposed on the basis of their strong absorbance in near-infrared region (NIR), vertical triplet energies resulting higher than 0.98 eV, and the spin-orbit matrix elements lager than 0.24 cm −1 . Moreover, an evaluation of triplet excited states lifetime is presented. The longer lifetime of the triplet excited states would lead to higher 1 O 2 yields for Pd(NˆCˆN)Cl compared to Pt(NˆCˆN)Cl. It is expected that the low-cost Pd(NˆCˆN)Cl will replace the reported Pt(NˆCˆN)Cl as a promising two-photon PS for improving clinical PDT efficacy. [ABSTRACT FROM AUTHOR]

This paper presents the hysteretic behavior of square concrete-filled steel tubular (CFT) stub columns with binding bars. A total of ten square CFT stub columns including eight specimens with binding bars and two specimens without binding bars were tested under constant axial load and cyclic lateral loads. The effects of the axial load level and the spacing of binding bars on the hysteretic behavior were investigated carefully. Experimental results demonstrate that the specimens with binding bars show higher lateral bearing capacity, higher stiffness, higher ultimate deformation capacity and better energy-dissipation capacity compared with those without binding bars. In addition, the initial local buckling for specimens with binding bars is significantly delayed by the binding bars. Furthermore, the lateral bearing capacity, the ultimate deformation capacity, the energy-dissipation capacity and the stiffness of the specimens with binding bars are significantly improved with the spacing of binding bars decreasing. The ultimate deformation capacity decreases with an increase in axial load levels while the energy-dissipation capacity increases with an increase in axial load levels. Finally, the fiber element analysis for all specimens is carried out. The calculated envelope curves and the calculated hysteretic curves of the specimens by the fiber element analysis are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]