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RITS acts in cis to promote RNA interference-mediated transcriptional and post-transcriptional silencing 总被引:10,自引:0,他引:10
Noma K Sugiyama T Cam H Verdel A Zofall M Jia S Moazed D Grewal SI 《Nature genetics》2004,36(11):1174-1180
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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
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Farhad Khorramshahi Mohammadabad Sina Hejazi Jalil Vahdati khaki Abolfazl Babakhani 《矿物冶金与材料学报》2016,23(4):380-388
This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching (mechanochemical leaching) of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to determine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide (H2O2) and ferric sulfate (Fe2(SO4)3) after 20 h of mechanochemical leaching reached 28% and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry. 相似文献
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Ataallah Bahrami Mirsaleh Mirmohammadi Yousef Ghorbani Fatemeh Kazemi Morteza Abdollahi Abolfazl Danesh 《北京科技大学学报》2019,(4)
The aim of this study is to apply process mineralogy as a practical tool for further understanding and predicting the flotation kinetics of the copper sulfide minerals. The minerals' composition and association, grain distribution, and liberation within the ore samples were analyzed in the feed, concentrate, and the tailings of the flotation processes with two pulp densities of 25 wt% and 30 wt%. The major copper-bearing minerals identified by microscopic analysis of the concentrate samples included chalcopyrite(56.2 wt%), chalcocite(29.1 wt%),covellite(6.4 wt%), and bornite(4.7 wt%). Pyrite was the main sulfide gangue mineral(3.6 wt%) in the concentrates. A 95% degree of liberation with d_(80) 80 μm was obtained for chalcopyrite as the main copper mineral in the ore sample. The recovery rate and the grade in the concentrates were enhanced with increasing chalcopyrite particle size. Chalcopyrite particles with a d_(80) of approximately 100 μm were recovered at the early stages of the flotation process. The kinetic studies showed that the kinetic second-order rectangular distribution model perfectly fit the flotation test data. Characterization of the kinetic parameters indicated that the optimum granulation distribution range for achieving a maximum flotation rate for chalcopyrite particles was between the sizes 50 and 55 μm. 相似文献
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Tung SY Hong JY Walz T Moazed D Liou GG 《Cellular and molecular life sciences : CMLS》2012,69(4):641-650
In the cell, many small endogenous metabolic molecules are involved in distinct cellular functions such as modulation of chromatin
structure and regulation of gene expression. O-acetyl-ADP-ribose (AAR) is a small metabolic molecule that is generated during NAD-dependent deacetylation by Sir2. Sir2
regulates gene expression, DNA repair, and genome stability. Here, we developed a novel chromatin affinity-precipitation (ChAP)
method to detect the chromatin fragments at which small molecules interact with binding partners. We used this method to demonstrate
that AAR associated with heterochromatin. Moreover, we applied the ChAP method to whole genome tiling array chips to compare
the association of AAR and Sir2. We found that AAR and Sir2 displayed similar genomic binding patterns. Furthermore, we identified
312 potential association cluster regions of AAR. The ChAP assay may therefore be a generally useful strategy to study the
small molecule association with chromosomal regions. Our results further suggest that the small metabolic molecule AAR associates
with silent chromatin regions in a Sir2-dependent manner and provide additional support for the role of AAR in assembly of
silent chromatin. 相似文献
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Emanuela Talamonti Anna M. Pauter Abolfazl Asadi Alexander W. Fischer Valerio Chiurchiù Anders Jacobsson 《Cellular and molecular life sciences : CMLS》2017,74(15):2815-2826
Docosahexaenoic acid (DHA) is an omega-3 fatty acid obtained from the diet or synthesized from alpha-linolenic acid through the action of fatty acid elongases (ELOVL) and desaturases. DHA plays important roles in the central nervous system as well as in peripheral organs and is the precursor of several molecules that regulate resolution of inflammation. In the present study, we questioned whether impaired synthesis of DHA affected macrophage plasticity and polarization both in vitro and in vivo models. For this we investigated the activation status and inflammatory response of bone marrow-derived M1 and M2 macrophages obtained from mice deficient of Elovl2 (Elovl2?/?), a key enzyme for DHA synthesis in mammals. Although both wild type and Elovl2?/? mice were able to generate efficient M1 and M2 macrophages, M1 cells derived from Elovl2?/? mice showed an increased expression of key markers (iNOS, CD86 and MARCO) and cytokines (IL-6, IL-12 and IL-23). However, M2 macrophages exhibited upregulated M1-like markers like CD80, CD86 and IL-6, concomitantly with a downregulation of their signature marker CD206. These effects were counteracted in cells obtained from DHA-supplemented animals. Finally, white adipose tissue of Elovl2?/? mice presented an M1-like pro-inflammatory phenotype. Hence, impairment of systemic DHA synthesis delineates an alteration of M1/M2 macrophages both in vitro and in vivo, with M1 being hyperactive and more pro-inflammatory while M2 less protective, supporting the view that DHA has a key role in controlling the balance between pro- and anti-inflammatory processes. 相似文献
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Ioannidis JP Gwinn M Little J Higgins JP Bernstein JL Boffetta P Bondy M Bray MS Brenchley PE Buffler PA Casas JP Chokkalingam A Danesh J Smith GD Dolan S Duncan R Gruis NA Hartge P Hashibe M Hunter DJ Jarvelin MR Malmer B Maraganore DM Newton-Bishop JA O'Brien TR Petersen G Riboli E Salanti G Seminara D Smeeth L Taioli E Timpson N Uitterlinden AG Vineis P Wareham N Winn DM Zimmern R Khoury MJ;Human Genome Epidemiology Network the Network of Investigator Networks 《Nature genetics》2006,38(1):3-5
Networks of investigators have begun sharing best practices, tools and methods for analysis of associations between genetic variation and common diseases. A Network of Investigator Networks has been set up to drive the process, sponsored by the Human Genome Epidemiology Network. A workshop is planned to develop consensus guidelines for reporting results of genetic association studies. Published literature databases will be integrated, and unpublished data, including 'negative' studies, will be captured by online journals and through investigator networks. Systematic reviews will be expanded to include more meta-analyses of individual-level data and prospective meta-analyses. Field synopses will offer regularly updated overviews. 相似文献
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