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1.
Catherine E. Waters Joshua C. Saldivar Seyed Ali Hosseini Kay Huebner 《Cellular and molecular life sciences : CMLS》2014,71(23):4577-4587
The FHIT gene at FRA3B is one of the earliest and most frequently altered genes in the majority of human cancers. It was recently discovered that the FHIT gene is not the most fragile locus in epithelial cells, the cell of origin for most Fhit-negative cancers, eroding support for past claims that deletions at this locus are simply passenger events that are carried along in expanding cancer clones, due to extreme vulnerability to DNA damage rather than to loss of FHIT function. Indeed, recent reports have reconfirmed FHIT as a tumor suppressor gene with roles in apoptosis and prevention of the epithelial–mesenchymal transition. Other recent works have identified a novel role for the FHIT gene product, Fhit, as a genome “caretaker.” Loss of this caretaker function leads to nucleotide imbalance, spontaneous replication stress, and DNA breaks. Because Fhit loss-induced DNA damage is “checkpoint blind,” cells accumulate further DNA damage during subsequent cell cycles, accruing global genome instability that could facilitate oncogenic mutation acquisition and expedite clonal expansion. Loss of Fhit activity therefore induces a mutator phenotype. Evidence for FHIT as a mutator gene is discussed in light of these recent investigations of Fhit loss and subsequent genome instability. 相似文献
2.
Seyed Mahmood Hosseini Abdolmotalleb Rezaei 《Systemic Practice and Action Research》2013,26(2):131-152
This article explores the potentials of systems analysis and design of information system for sustainable natural resource management. Soft and hard system analyses were performed to better understand the information needs and design of an information system for improving decision making for achieving sustainable natural resource management. In order to analyze the complex and soft systems situations for developing an effective information system, which meets related actors’ changing needs, a conceptual model inspired by soft systems methodology (SSM) was developed. This model is based on information derived from twelve farmers who were purposely selected to represent diverse conditions and 23 agricultural extension experts across the Alborz Watershed in Mazandaran Province, located in northern Iran. Since a conceptual model resulting from SSM is not in itself sufficient as the basis for the implementation of information systems, a hard system methodology was used to structure the data handling by using unified modeling language. This research has shown the promising potentiality of using soft system analysis methodology as a preliminary step to the actual design of an information system in the natural resource management situation in the watershed system level when combined with hard system analysis methods. 相似文献
3.
This paper presents an analysis of shift-contagion in energy markets, testing whether linkages between returns in energy markets increase during crisis periods. The research presented herein demonstrates how common movement between energy markets increases due to (i) shift-contagion across energy markets, reflected by structural transmission of shocks across markets and (ii) larger common shocks operating through standard cross-market interdependences. A regime-switching model was developed to detect shift-contagion across energy markets. In the approach adopted herein, the occurrence of shift-contagion is endogenously estimated rather than being exogenously assigned. The results show that shift-contagion has been a major feature of energy markets over the last decade. Evidence is presented which demonstrates that the linkages between energy markets do not appear to be stable. These results are remarkably accurate for forecasting Brent and natural gas for horizons for up to 50 days. Conversely, for WTI (West Texas Intermediate oil) and coal, the model performs well only for forecasting very short horizons (up to 20 days). For all products, the model shows significant biases for long horizons. 相似文献
4.
Lifestyle transitions in plant pathogenic Colletotrichum fungi deciphered by genome and transcriptome analyses 总被引:8,自引:0,他引:8
RJ O'Connell MR Thon S Hacquard SG Amyotte J Kleemann MF Torres U Damm EA Buiate L Epstein N Alkan J Altmüller L Alvarado-Balderrama CA Bauser C Becker BW Birren Z Chen J Choi JA Crouch JP Duvick MA Farman P Gan D Heiman B Henrissat RJ Howard M Kabbage C Koch B Kracher Y Kubo AD Law MH Lebrun YH Lee I Miyara N Moore U Neumann K Nordström DG Panaccione R Panstruga M Place RH Proctor D Prusky G Rech R Reinhardt JA Rollins S Rounsley CL Schardl DC Schwartz N Shenoy K Shirasu UR Sikhakolli K Stüber 《Nature genetics》2012,44(9):1060-1065
5.
Malaria is a mosquito-borne disease that is transmitted by inoculation of the Plasmodium parasite sporozoite stage. Sporozoites invade hepatocytes, transform into liver stages, and subsequent liver-stage development ultimately results in release of pathogenic merozoites. Liver stages of the parasite are a prime target for malaria vaccines because they can be completely eliminated by sterilizing immune responses, thereby preventing malarial infection. Using expression profiling, we previously identified genes that are only expressed in the pre-erythrocytic stages of the parasite. Here, we show by reverse genetics that one identified gene, UIS3 (upregulated in infective sporozoites gene 3), is essential for early liver-stage development. uis3-deficient sporozoites infect hepatocytes but are unable to establish blood-stage infections in vivo, and thus do not lead to disease. Immunization with uis3-deficient sporozoites confers complete protection against infectious sporozoite challenge in a rodent malaria model. This protection is sustained and stage specific. Our findings demonstrate that a safe and effective, genetically attenuated whole-organism malaria vaccine is possible. 相似文献
6.
Metallic materials are the most used materials as orthopedic or dental implants due to
their excellent mechanical properties. However they are not able to create a natural bonding with
the mineralized bone and occasionally suffer localized corrosion. This work describes the
electrochemical behavior of a hybrid sol–gel thin film with the addition of green inhibitor. These
films enhance the ability of the implant to make a union with the existing bone and improve its
resistance to aggressive environment. An ethanol solution of the polymerized vinyltrimethoxysilane
(PVTMS) was mixed with an aqueous solution of henna extract (Lawsonia inermis) and refluxed to
give homogeneous sols. Nanostructure hybrid PVTMS/henna thin films were deposited on the
stainless steel 316L by spin-coating. The morphology, composition and adhesion of hybrid sol–gel
coatings have been examined by SEM, EDX and pull-off test, respectively. Addition of high
additive concentrations (0.1%) did not disorganize the sol–gel network. Direct pull-off test
recorded a mean coating-substrate bonding strength larger than 20.6 MPa for the hybrid sol–gel
coating. The effect of henna extract, with various added concentrations from 0.012% to 0.1%, on
the anticorrosion properties of sol–gel films have been characterized by electrochemical impedance
spectroscopy (EIS) and potentiodynamic polarization tests in simulated body fluid (SBF) solution
and has been compared to the bare metal. Henna extract additions (0.05%) have significantly
increased the corrosion protection of the sol–gel thin film to higher than 90%. The in vitro
bioactivity of prepared films indicates that hydroxyapatite nuclei can form and grow on the surface
of the doped sol–gel thin films. The present study shows that due to their excellent anticorrosion properties, bioactivity and bonding strength to substrate, doped sol–gel thin films are practical
hybrid films in biomedical applications. 相似文献
7.
Mehdi Haj Hojjatollah Mansouri Reza Vafaei Golam Reza Ebrahimi Ali Kanani 《矿物冶金与材料学报》2013,20(6):529-534
The hot compression behavior of AISI 321 austenitic stainless steel was studied at the temperatures of 950–1100℃ and the strain rates of 0.01–1 s?1 using a Baehr DIL-805 deformation dilatometer. The hot deformation equations and the relationship between hot deformation parameters were obtained. It is found that strain rate and deformation temperature significantly influence the flow stress behavior of the steel. The work hardening rate and the peak value of flow stress increase with the decrease of deformation temperature and the increase of strain rate. In addition, the activation energy of deformation (Q) is calculated as 433.343 kJ/mol. The microstructural evolution during deformation indicates that, at the temperature of 950℃ and the strain rate of 0.01 s?1, small circle-like precipitates form along grain boundaries; but at the temperatures above 950℃, the dissolution of such precipitates occurs. Energy-dispersive X-ray analyses indicate that the precipitates are complex carbides of Cr, Fe, Mn, Ni, and Ti. 相似文献
8.
Biodegradable starch/poly (vinyl alcohol) film reinforced with titanium dioxide nanoparticles 总被引:1,自引:0,他引:1
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Zahra Hejri Ali Akbar Seifkordi Ali Ahmadpour Seyed Mojtaba Zebarjad Abdolmajid Maskooki 《矿物冶金与材料学报》2013,20(10):1001-1011
Biodegradable starch/poly (vinyl alcohol)/nano-titanium dioxide (ST/PVA/nano-TiO2) nanocomposite films were prepared via a solution casting method. Their biodegradability, mechanical properties, and thermal properties were also studied in this paper. A general full factorial experimental approach was used to determine effective parameters on the mechanical properties of the prepared films. ST/PVA/TiO2 nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of mechanical analysis show that ST/PVA films with higher contents of PVA have much better mechanical properties. In thermal analysis, it is found that the addition of TiO2 nanoparticles improves the thermal stability of the films. SEM micrographs, taken from the fracture surface of samples, illustrate that the addition of PVA makes the film softer and more flexible. The results of soil burial biodegradation indicate that the biodegradability of ST/PVA/TiO2 films strongly depends on the starch proportion in the film matrix. The degradation rate is increased by the addition of starch in the films. 相似文献
9.
Ali Rasooli Mehdi Divandari Hamid Reza Shahverdi Mohammad Ali Boutorabi 《矿物冶金与材料学报》2012,19(2):165-172
Based on the measurement of the released hydrogen gas pressure (PH2), the reaction kinetics between TiH2 powder and pure aluminum melt was studied at various temperatures. After cooling the samples, the interface of TiH2 powder and aluminum melt was studied. The results show that the 2 H PH2-time curves have three regions; in the first and second regions, the rate of reaction conforms zero and one order, respectively; in the third region, the hydrogen gas pressure remains constant and the rate of reaction reaches zero. The main factors that control the rate of reaction in the first and second regions are the penetration of hydrogen atoms in the titanium lattice and the chemical reaction between molten aluminum and titanium, respectively. According to the main factors that control the rate of reaction, three temperature ranges are considered for the reaction mechanism:(a) 700-750℃, (b) 750-800℃, and (c) 800-1000℃. In the first temperature range, the reaction is mostly under the control of chemical reaction; at the temperature range of 750 to 800℃, the reaction is controlled by the diffusion and chemical reaction; at the third temperature range (800-1000℃), the dominant controlling mechanism is diffusion. 相似文献
10.
Mehdi Shahedi Asl Abbas Sabahi Namini Seyed Ali Delbari Quyet Van Le Mohammadreza Shokouhimehr Mohsen Mohammadi 《自然科学进展(英文版)》2021,31(1):47-54
Sintering behavior of ZrB2 ceramic with nano-sized SiC dopant was studied. ZrB2-25 vol% nano-sized SiC was selected as the starting mixture to fabricate the composite. The manufacturing process was accomplished at 1800℃ for 5 min under 25 MPa via spark plasma sintering(SPS). The as-sintered sample reached a relative density of 99%. Besides the initial phases, namely ZrB2 and SiC, the high-resolution X-ray diffraction(HRXRD) was used to study the formation of an i... 相似文献