Experimental Study on Carbonation of Steel Fiber Reinforced Concrete

With the steel fiber reinforced concrete (SFRC) used more and more widely in some large-span structures, large tunnel linings, dam structures, military engineering, and some other major projects, its durability arouses more and more concerns. In this paper carbonation test of SFRC was conducted. The rule for the mixing amount of steel fiber (0, 0.5, 1.0, 1.5, and 2.0%) to affect the carbonation depth of concrete and the strength developing rule of SFRC after carbonation test were researched. To analyze the property change rules from micro perspective of SFRC after carbonation, the pore structure of SFRC after carbonation was tested. The results show that appropriate amount of steel fiber can retard the speed of concrete carbonation; the concrete carbonation speed is the slowest when the fiber content is 1.5%, and the carbonation speed is accelerated when the fiber content is increased to 2%. Carbonation can change the pore structure of SFRC, total porosity, total pore volume, and total pore areas reduced and makes the pore structure of concrete going more reasonable. Carbonation can improve the splitting tensile strength of SFRC to certain extent

Selection Method for Kernel Function in Nonparametric Extrapolation Based on Multicriteria Decision-Making Technology

Selecting the most appropriate kernel function to extrapolate a load set is the paramount step in compiling load spectrum, as it affects the results of nonparametric extrapolation largely. Aiming at this issue, this paper provides a new approach in selecting kernel function for the nonparametric extrapolation. To solve the complexity and uncertainty of nonparametric extrapolation, characteristics of four kernel functions and their effects on the results are explained in the “from-to” diagram obtained by rainflow counting. Multicriteria decision-making (MCDM) is then applied to solve the selection problem of kernel function. To evaluate the dispersion degrees of the mean and amplitude of a load set accurately, their range, standard deviation, and interquartile range are selected as the evaluation criteria. The weight of each criterion, which represents the impact degree on the selection of the kernel function, is calculated separately using the eigenvector and entropy method. The comprehensive weights are obtained by applying the optimization theory and Jaynes’ maximum entropy principle. Finally, the importance of each criterion is discussed according to their calculated comprehensive weights, and the selection method for kernel functions is obtained, which is illustrated by extrapolating the output torque of the power split device of hybrid electrical vehicles

Primary culture of human blood-retinal barrier cells and preliminary study of APOBEC3 expression

PURPOSE. To develop methods for primary culture of human blood-retinal barrier (BRB) cells and to explore the expression of APOBEC3 (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3) family gene, novel host-defense factors to HIV-1. METHODS. Cellular components of human BRB (human retinal capillary endothelial cells [HRCECs], human retinal capillary pericytes, and human retinal pigment epithelial cells) were isolated separately and subjected to primary culture according to procedures modified in our laboratory. Immunocytochemistry and immunofluorescence were used to identify specific markers of the primary cells and to analyze their purity by flow cytometry. RNA of the three different cells was isolated, and primers were designed to probe expression of the APOBEC3 gene by reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. For further confirmation, APOBEC3F and APOBEC3G proteins were detected in the cultured cells and fresh retina tissue through Western blot analysis. In the end, HRCECs were treated with IFN-␥, and change of APOBEC3G expression was displayed. RESULTS. Pure BRB cells (Ͼ95% purity) were primary cultured according to procedures modified in our laboratory. Qualitative test of RT-PCR and semiquantitative examination of realtime PCR demonstrated the presence of APOBEC3B, -3C, -3F, and -3G genes and the absence of APOBEC3A and -3D genes in all cellular components of the BRB. Finding of the APOBEC3G and APOBEC3F proteins expressed in the three primary cultured cells and different layers of retinal tissue by Western blot analysis further confirmed the PCR results. Moreover, IFN-␥ could upregulate the expression of APOBEC3G in HRCECs. CONCLUSIONS. Major cellular components of human BRB could be primary cultured in vitro according to procedures optimized in our laboratory. Different expression of APOBEC3 in human blood-retinal barrier gives a clue to further research in intrinsic antiviral immunity in HIV-1-related retinopathy. (Invest Ophthalmol Vis Sci. 2009;50:4436 -4443

Ligand and structure-based approaches for the exploration of structure–activity relationships of fusidic acid derivatives as antibacterial agents

Introduction: Fusidic acid (FA) has been widely applied in the clinical prevention and treatment of bacterial infections. Nonetheless, its clinical application has been limited due to its narrow antimicrobial spectrum and some side effects.Purpose: Therefore, it is necessary to explore the structure–activity relationships of FA derivatives as antibacterial agents to develop novel ones possessing a broad antimicrobial spectrum.Methods and result: First, a pharmacophore model was established on the nineteen FA derivatives with remarkable antibacterial activities reported in previous studies. The common structural characteristics of the pharmacophore emerging from the FA derivatives were determined as those of six hydrophobic centers, two atom centers of the hydrogen bond acceptor, and a negative electron center around the C-21 field. Then, seven FA derivatives have been designed according to the reported structure–activity relationships and the pharmacophore characteristics. The designed FA derivatives were mapped on the pharmacophore model, and the Qfit values of all FA derivatives were over 50 and FA-8 possessed the highest value of 82.66. The molecular docking studies of the partial target compounds were conducted with the elongation factor G (EF-G) of S. aureus. Furthermore, the designed FA derivatives have been prepared and their antibacterial activities were evaluated by the inhibition zone test and the minimum inhibitory concentration (MIC) test. The derivative FA-7 with a chlorine group as the substituent group at C-25 of FA displayed the best antibacterial property with an MIC of 3.125 µM. Subsequently, 3D-QSAR was carried on all the derivatives by using the CoMSIA mode of SYBYL-X 2.0.Conclusion: Hence, a computer-aided drug design model was developed for FA, which can be further used to optimize FA derivatives as highly potent antibacterial agents

Synthesis and Biological Evaluation of Novel Fusidic Acid Derivatives as Two-in-One Agent with Potent Antibacterial and Anti-Inflammatory Activity

Fusidic acid (FA), a narrow-spectrum antibiotics, is highly sensitive to various Gram-positive cocci associated with skin infections. It has outstanding antibacterial effects against certain Gram-positive bacteria whilst no cross-resistance with other antibiotics. Two series of FA derivatives were synthesized and their antibacterial activities were tested. A new aromatic side-chain analog, FA-15 exhibited good antibacterial activity with MIC values in the range of 0.781-1.563 µM against three strains of Staphylococcus spp. Furthermore, through the assessment by the kinetic assay, similar characteristics of bacteriostasis by FA and its aromatic derivatives were observed. In addition, anti-inflammatory activities of FA and its aromatic derivatives were evaluated by using a 12-O-tetradecanoylphorbol-13-acetate (TPA) induced mouse ear edema model. The results also indicated that FA and its aromatic derivatives effectively reduced TPA-induced ear edema in a dose-dependent manner. Following, multiform computerized simulation, including homology modeling, molecular docking, molecular dynamic simulation and QSAR was conducted to clarify the mechanism and regularity of activities. Overall, the present work gave vital clues about structural modifications and has profound significance in deeply scouting for bioactive potentials of FA and its derivatives

The inhibitory effect of different concentrations of KH902 eye drops on corneal neovascularization induced by alkali burn

Purpose: The aim of this study was to evaluate the inhibitory effect of different concentrations of KH902 eye drops on rabbit corneal neovascularization (CNV) induced by alkali burn. Methods: Forty-eight adult rabbits were randomized into four groups after alkali burning: Group A (2.5 mg/ml), Group B (5 mg/ml), and Group C (10 mg/ml) by different concentrations of KH902 eye drops and Group D by saline solution as control with three times a day for 2 weeks. At days 7, 14, and 28, the anterior segment photographs, confocal microscopy, and histopathology were performed to evaluate corneal opacity, neovascularization, inflammatory cell density, vessel size, and edema. Immunohistochemistry was applied to analyze the vascular endothelial growth factor (VEGF) level. Results: (1) The CNV in the medicine-treated groups showed a reduction without obvious corneal side effects histologically. (2) Compared to the control group, the three medicine-treated groups showed a reduction in the VEGF levels and CNV areas on days 7, 14, and 28 and in the inflammatory cell density on days 14 and 28 (P 0.05). Conclusion: KH902 eye drops in lower concentration showed an obvious reduction of the CNV growing for rabbit corneal alkali burn without side effects

Investigations on the discharge and total temperature increase characteristics of the labyrinth seals with honeycomb and smooth lands

ABSTRACT The viscous work generated by the rotating components of the seal not only represents the direct loss of power, but also causes the increase in total temperature of fluid (windage effect). In order to study the discharge and total temperature increase characteristics of the stepped labyrinth seals with smooth and honeycomb lands, 3D RANS solutions from CFX is used in this work. At first, the influences of the inlet preswirl, leakage flow rate and rotational speed on the total temperature increase in the convergent and divergent stepped labyrinth seals with smooth and honeycomb lands are conducted. The obtained 3D numerical results are well in agreement with the referenced experimental data. It shows that the utilized numerical approach has sufficient precision to predict the total temperature increase in seals. Then, a range of pressure ratios and four sizes of sealing clearance are performed to investigate the effects of sealing clearances and pressure ratios impact on the discharge and total temperature increase of the stepped labyrinth seals with honeycomb and smooth liners. Greek letters

What limit the research productivity of universities? A case study of a Chinese university

In the era of knowledge economy, university plays an important role in the development of community. Generally, universities are responsible for three missions, i.e. teaching, research and social service. Among them, research lunes at the centre, which provides latest intellectual products for teaching on one hand, and supports social service with advanced practices on the other hand. Critical and influential as it is, after investigation we found that the research productivity of the leading research universities in China is quite stable and thus may not meet the expectation of stakeholders. To address this issue, first we conduct an unstructured interview to conclude the limiting factors and causal loop diagram is built. Then a simulation model is developed and alternative polices are tested. It is founded that there are four limits to growth structures in the system, which help to explain the stagnant performance of research productivity. Based on sensitivity test and analysis of implementation cost and risk, we suggest university to provide training and supports to shorten the assimilation time and to increase maximal recruiting rate to response to the requirement of teaching and projects more promptly