Workability and mechanical properties of alkali-activated fly ash-slag concrete cured at ambient temperature

Alkali-activated fly ash-slag (AAFS) concrete is a new blended alkali-activated concrete that has been increasingly studied over the past decades because of its environmental benefits and superior engineering properties. However, there is still a lack of comprehensive studies on the effect of different factors on the fresh and hardened properties of AAFS concrete. This paper aims to provide a thorough understanding of workability and mechanical properties of AAFS concrete cured at ambient temperature and to obtain the optimal mixtures for engineering application. A series of experiments were carried out to measure workability, setting time, compressive strength, splitting tensile strength, flexural strength and dynamic elastic modulus of AAFS concrete. The results showed that workability and setting time decreased with the increase of slag content and molarity of sodium hydroxide solution (SH). Compressive strength increased with the increase of slag content and molarity of SH as well as the decrease of alkaline activator to binder (AL/B) ratio, but it did not have significant relationship with sodium silicate to sodium hydroxide (SS/SH) ratio. In addition, equations provided by ACI code, Eurocode and previous researchers for ordinary Portland cement concrete overestimated the values of splitting tensile strength, flexural strength and dynamic elastic modulus of AAFS concrete. The optimal mixtures of AAFS concrete were set as slag content of 20–30%, AL/B ratio of 0.4, 10 M of SH, and SS/SH ratio of 1.5–2.5 considering the performance criteria of workability, setting time and compressive strength

The Proliferation and Migration Effects of Huangqi on RSC96 Schwann Cells

[[abstract]]This study evaluated the proliferation effects of huangqi on neuron regeneration. We investigated the molecular mechanisms, which include: (1) cyclin D1, A, E-cell cycle factors and MAPK signaling proliferation (2) FGF-2-UPA-MMPs migration signaling. After treatment with various Huanqi concentrations (1.25, 12.5, 125, 250 and 500 mu g/ml,), we observed that Huanqi can increase Rsc 96 cell proliferation at 12.5 mu g/ml (p < 0.01) concentration determined by the MTT and wound healing tests. Examination by RT-PCR and Western blotting assay showed that Huangqi is able to stimulate the mRNA and protein expressions of cyclin D1, A, E, cell cycle controlling proteins and excite ERK and P38 MAPK signaling pathways to promote cell proliferation. Huangqi stimulates the FGF-2-UPA-MMP9 migration pathway and enhances RSC 96 Schwann cells migration. Using MAPK chemical inhibitors, U0126, SB203580 and SP600125, the proliferative effects of Huangqi oil RSC 96 cells were ERK and P38 signaling-dependent. Based oil these results, applying an appropriate dose of Huangqi with biomedical materials would be a potential approach to enhancing neuron regeneration

Antecedent Avian Immunity Limits Tangential Transmission of West Nile Virus to Humans

Background: West Nile virus (WNV) is a mosquito-borne flavivirus maintained and amplified among birds and tangentially transmitted to humans and horses which may develop terminal neuroinvasive disease. Outbreaks typically have a three-year pattern of silent introduction, rapid amplification and subsidence, followed by intermittent recrudescence. Our hypothesis that amplification to outbreak levels is contingent upon antecedent seroprevalence within maintenance host populations was tested by tracking WNV transmission in Los Angeles, California from 2003 through 2011. Methods: Prevalence of antibodies against WNV was monitored weekly in House Finches and House Sparrows. Tangential or spillover transmission was measured by seroconversions in sentinel chickens and by the number of West Nile neuroinvasive disease (WNND) cases reported to the Los Angeles County Department of Public Health. Results: Elevated seroprevalence in these avian populations was associated with the subsidence of outbreaks and in the antecedent dampening of amplification during succeeding years. Dilution of seroprevalence by recruitment resulted in the progressive loss of herd immunity following the 2004 outbreak, leading to recrudescence during 2008 and 2011. WNV appeared to be a significant cause of death in these avian species, because the survivorship of antibody positive birds significantly exceeded that of antibody negative birds. Cross-correlation analysis showed that seroprevalence was negatively correlated prior to the onset of human cases and then positively correlated, peaking at 4–6 weeks after the onse

Nitrogen doped-ZnO/n-GaN heterojunctions

Nitrogen-doped ZnO nanorods were prepared by electrodeposition using two different Zn precursors (zinc nitrate and zinc acetate), while all other growth conditions (dopant precursor, concentration, growth temperature, and bias) were identical. We have shown that the precursor used affects the properties of the ZnO nanorods, and that the presence of rectifying properties in n-GaN/N:ZnO heterojunctions is strongly related to the use of nitrate precursor for ZnO growth. The difference in the properties of ZnO obtained from two precursors is attributed to the differences in native defect and impurity concentrations, which could affect the electronic properties of the samples. © 2011 American Institute of Physics.published_or_final_versio

Solution-based growth of ZnO nanorods for light-emitting devices: Hydrothermal vs. electrodeposition

ZnO nanorods have been grown by two inexpensive, solution-based, low-temperature methods: hydrothermal growth and electrodeposition. Heterojunction n-ZnO nanorods/p-GaN light-emitting diodes have been studied for different nanorod growth methods and different preparation of the seed layer. We demonstrate that both the nanorod properties and the device performance are strongly dependent on the growth method and seed layer. All the devices exhibit light emission under both forward and reverse bias, and the emission spectra can be tuned by ZnO nanorod deposition conditions. Electrodeposition of rods or a seed layer results in yellow emission, while conventional hydrothermal growth results in violet emission. © The Author(s) 2010. This article is published with open access at Springerlink.com.published_or_final_versionSpringer Open Choice, 01 Dec 201

Nitrogen doped-ZnO/n-GaN heterojunctions

Author name used in this publication: Aleksandra B. DjurišičAuthor name used in this publication: Kok Wai CheahAuthor name used in this publication: Chi Chung LingAuthor name used in this publication: Wai Kin ChanAuthor name used in this publication: Patrick W. K. FongAuthor name used in this publication: Hsian Fei Lui2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Comparison of Argentinean Saint Louis Encephalitis Virus Non-Epidemic and Epidemic Strain Infections in an Avian Model

St. Louis encephalitis virus (SLEV, Flavivirus, Flaviviridae) is an emerging mosquito-borne pathogen in South America, with human SLEV encephalitis cases reported in Argentina and Brazil. Genotype III strains of SLEV were isolated from Culex quinquefasciatus mosquitoes in Cordoba, Argentina in 2005, during the largest SLEV outbreak ever reported in South America. The present study tested the hypothesis that the recent, epidemic SLEV strain exhibits greater virulence in birds as compared with a non-epidemic genotype III strain isolated from mosquitoes in Santa Fe Province 27 years earlier. The observed differences in infection parameters between adult House sparrows (Passer domesticus) that were needle-inoculated with either the epidemic or historic SLEV strain were not statistically significant. However, only the House sparrows that were infected with the epidemic strain achieved infectious-level viremia titers sufficient to infect Cx. spp. mosquitoes vectors. Furthermore, the vertebrate reservoir competence index values indicated an approximately 3-fold increase in amplification potential of House sparrows infected with the epidemic strain when pre-existing flavivirus-reactive antibodies were present, suggesting the possibility that antibody-dependent enhancement may increase the risk of avian-amplified transmission of SLEV in South America

A Bayesian Network Driven Approach to Model the Transcriptional Response to Nitric Oxide in Saccharomyces cerevisiae

The transcriptional response to exogenously supplied nitric oxide in Saccharomyces cerevisiae was modeled using an integrated framework of Bayesian network learning and experimental feedback. A Bayesian network learning algorithm was used to generate network models of transcriptional output, followed by model verification and revision through experimentation. Using this framework, we generated a network model of the yeast transcriptional response to nitric oxide and a panel of other environmental signals. We discovered two environmental triggers, the diauxic shift and glucose repression, that affected the observed transcriptional profile. The computational method predicted the transcriptional control of yeast flavohemoglobin YHB1 by glucose repression, which was subsequently experimentally verified. A freely available software application, ExpressionNet, was developed to derive Bayesian network models from a combination of gene expression profile clusters, genetic information and experimental conditions

ZnO nanorod/GaN light-emitting diodes : the origin of yellow and violet emission bands under reverse and forward bias

Author name used in this publication: Xinyi ChenAuthor name used in this publication: Alan Man Ching NgAuthor name used in this publication: Aleksandra B DjurišićAuthor name used in this publication: Kok Wai CheahAuthor name used in this publication: Patrick Wai Keung Fong2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe