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Repression of transcription mediated by dual elements in the ccAAT/enhancer binding protein alpha gene

PROcEEDINGS OF THE NATIONAL AcADEMY OF ScIENcES OF THE UNITED STATES OF AMERIcA 1997年第25期94卷 13571-13575页

作者： Tang, QQ Jiang, MS Lane, MD JOHNS HOPKINS UNIV SCH MEDDEPT BIOL CHEMBALTIMOREMD 21205

During adipocyte differentiation, the expression of c/EBP alpha is activated, which in turn serves to transcriptionally activate numerous adipocyte genes. A previous search for cis elements that regulate transcription of the c/EBP alpha gene led to the identification of a potential repressive element within the proximal 5' flanking region of the gene. Nuclear extracts from 3T3-L1 preadipocytes, but not adipocytes, were found to contain a factor, cUP (c/EBP alpha undifferentiated protein), that binds to this site (the cUP-1 site). In the present investigation, we show that c/EBP alpha promoter-luciferase constructs containing both the proximal 5' flanking and the entire 5' untranslated regions of the gene exhibit an expression pattern during adipocyte differentiation comparable to that of the endogenous c/EBP alpha gene. Mutation of the cUP-1 site in these constructs had little effect on reporter gene expression;however, when this mutation was combined with deletion of the 5' untranslated region, reporter gene expression by preadipocytes was dramatically up-regulated. consistent with this finding, a second cUP binding site (the cUP-2 site) was identified in the 5' untranslated region. Although mutation of either cUP element in constructs containing both the 5' flanking and 5' untranslated region had little effect on reporter gene transcription, mutation of both cUP elements markedly activated transcription. Thus, it appears that dual cUP regulatory elements repress transcription of the c/EBP alpha gene prior to induction of the adipocyte differentiation program.

关键词： 3T3-L1 cells preadipocyte adipocyte differentiation adipose c EBP alpha undifferentiated protein

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Size-tunable synthesis of mono-disperse wastewater-derived carbon spheres with polyacrylamide as a directing agent

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MIcRO & NANO LETTERS 2015年第10期10卷 603-606页

作者： Tang, chuanqiu Zhang, Pingping Sun, Yong Bai, Li Yunyang Teachers Coll Dept Chem Biol & Environm Engn Shiyan 442000 Hubei Peoples R China Wuhan Univ Minist Educ Key Lab Analyt Chem Biol & Med Wuhan 430072 Peoples R China

Highly mono-disperse carbon spheres (cSs) with a tunable diameter of 300-4000 nm are shown to be successfully synthesised using sugar-rich wastewater as carbon sources and polyacrylamide (PAM) as a size-controlling agent. The effects of PAM and pH on the morphology and size were also investigated. Experimental results showed that PAM acted as a size-directing agent which directs the self-assembly of sugar from wastewater to form the spheroidal particles. The size of cSs could be increased from 300 to 600 nm without any alteration in the morphologies by altering the solution pH from 7 to 12. Furthermore, the size of spheroidal carbon particles can be easily controlled by increasing the concentration of PAM from 0.05 to 0.1% (w/v) at pH 12. The largest sizes of cSs grew nearly 4000 nm without damage to their morphology or broadening of their size distribution with the addition of 0.1% PAM. On the basis of the experimental results, a mechanism is proposed to elucidate the formation of cSs with a wide diameter range. It is believed that this work not only provides a novel potential way to utilise wastewater, but also puts forward a facile sustainable approach to synthesise size-controllable cSs.

关键词： carbon particle size materials preparation wastewater polymers self-assembly sugar size-tunable synthesis mono-disperse wastewater-derived carbon spheres polyacrylamide directing agent sugar-rich wastewater polyacrylamide effects pH effects morphology size-directing agent self-assembly spheroidal carbon particles size size distribution size 300 nm to 4000 nm c

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Synthesis of carbon nanostructures from coal by chemical solid synthesis method

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MIcRO & NANO LETTERS 2016年第8期11卷 450-453页

作者： Fathabadi, Motahare Vakili Rafsanjani, Hasan Hashemipour Danafar, Firouze Shahid Bahonar Univ Dept Chem Engn Kerman Iran

carbon nanofibres (cNFs) and carbon spheres (cSs) are successfully synthesised using coal particles (<44 micron) in solid phase. coal and ferrocene as catalyst were fed to the reactor in the solid form. The reaction is carried out in a tubular reactor. The as-synthesised samples have been characterised through Raman spectroscopy, X-ray diffraction, scanning and transmission electron microscopy. The results show cNFs formed in 25-40 nm and mono dispersed cSs in 200-300 nm are amorphous. A feasible mechanism of cNFs and cSs formation from coal described here with the help of coal structure.

关键词： carbon fibres nanofibres catalysts Raman spectra X-ray diffraction scanning electron microscopy transmission electron microscopy amorphous state nanofabrication carbon nanostructures chemical solid synthesis method carbon nanofibres coal particles solid phase ferrocene catalyst tubular reactor Raman spectroscopy X-ray diffraction scanning electron microscopy transmission electron microscopy coal structure amorphous structure monodispersed carbon spheres c

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cOMPILER PERFORMANcE ANALYSIS TOOLS

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SOFTWARE-PRAcTIcE & EXPERIENcE 1988年第9期18卷 917-921页

作者： HEINES, TS JALIcS, PJ Department of Computer and Information Science Cleveland State University ClevelandOH 44115 U.S.A.

Most of the performance bench-marks for compilers do not give detailed performance characteristics that might be useful to a programmer. The goal of most bench-marks seems to be to produce a single number. A set of bench-mark tools that measure individual language features of c and generate a large number of measurements has been designed to create a detailed performance profile of any c compiler. There is an emphasis on the detailed statement-level measurements of both cPU and I/O aspects of c, but there is also a range of routine and program-level bench-marks that seek to measure the interaction of cPU and I/O in actual application programs. The programs are portable, parametrized, and openended so that additional measurements can be added with little effort. With some additional effort, the tools could be adapted to other languages.

关键词： Performance compiler c Tools Bench-marks Measurement

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Influence of mechanical strain on critical current density and microstructure of silver-sheathed Bi(Pb)2223 superconducting tapes

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PHYSIcA c 1996年第3-4期266卷 223-229页

作者： Yau, JKF Savvides, N Sorrell, cc CSIRO DIV APPL PHYSLINDFIELDNSW 2070AUSTRALIA

The influence of mechanical strain on the critical current density J(c) (77 K) of single- and multi-filament silver-sheathed Bi(Pb)2223 (Bi2-xPbxSr2ca2cu3O10-y) superconducting tapes was investigated by cyclic double-bend tests. The in;eversible strain limits epsilon(irr) determined were compared with those measured using single-bend tests. II was found that the decrease in the J(c) is determined primarily by the bending radius while cyclic stress caused further deterioration. However, a large percentage of the J(c) is retained at large strain (much greater than epsilon(irr)) and through repeated bending. Scanning electron microscopy revealed that the deterioration resulted from microstructural damage in the form of cracks. At strains just beyond the irreversible strain limit, cracks developed only on the sides of the samples subjected to tensile strains. At large strains, cracks also were found on the compressive sides. The magnetic field dependence of the J(c) was measured on samples subjected to various strain levels. The results suggest that the effect of strain on the J(c) is extrinsic and that microstructural damage is the only cause of the deterioration.

关键词： High- T c superconductor Strain tolerance critical current density Bi(Pb)2223 Superconducting tape

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Nd:YAG Nanosecond Laser Pulses for Precipitation Silver Nanoparticles in Silicate Glasses: Ac conductivity and Dielectric Studies

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SILIcON 2020年第1期12卷 13-20页

作者： Menazea, A. A. Abdelghany, A. M. Hakeem, N. A. Osman, W. H. Abd El-kader, F. H. Natl Res Ctr Div Phys Dept Spect 33 ElBehouth St Giza 12311 Egypt Natl Res Ctr Div Phys Laser Technol Unit 33 ElBehouth St Giza 12311 Egypt Horus Univ Dept Basic Sci Int Coastal Rd Kafr Saad Damietta Govern Egypt Cairo Univ Fac Sci Dept Phys Giza Egypt

Silicate glasses with chemical composition in mol%: (75 mol% SiO2-15 mol% Na2O-10 mol% ca2O) doped by different ratios (x) of AgNo3, (x = 0.0, 0.1, 0.5 and 1.0) were successfully prepared by melting method. Silver nanoparticles (AgNPs) have been precipitated in the prepared glasses via Nd:YAG nanosecond laser irradiation pulses. The A.c. conductivity behavior and the dielectric properties such as;(dielectric constant (epsilon') anddielectric loss (epsilon")), Ac conductivity (sigma(ac)' and sigma(ac)"), electric modulus (M' and M") and electric impedance (Z' and Z") have been investigated as a function of frequency for the prepared glass samples in the frequency range;from 0.1 Hz to 10 MHz at room temperature. The Ac conductivity is proportional to AgNO3 and increased as silver nanoparticles concentrations inside the silicate glass matrix increasing.

关键词： Nd YAG Nanosecond laser Ag nanoparticles Silicate glasses Dielectric properties A c conductivity

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Is graphene a good transparent electrode for photovoltaics and display applications?

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IET cIRcUITS DEVIcES & SYSTEMS 2015年第6期9卷 403-412页

作者： Bointon, Thomas H. Russo, Saverio craciun, Monica Felicia Univ Exeter Ctr Graphene Sci CEMPS Exeter EX4 4QL Devon England

The current standard material used for transparent electrodes in displays, touch screens and solar cells is indium tin oxide (ITO) which has low sheet resistance (10 /), high optical transmission in the visible wavelength (85%) and does not suffer of optical haze. However, ITO is mechanically rigid and incompatible with future demands for flexible applications. Graphene materials share many of the properties desirable for flexible transparent conductors, including high optical transparency, high mechanical flexibility and strength. Whilst pristine graphene is not a good transparent conductor, functionalised graphene is at least 1000 times a better conductor than its pristine counterpart and it outperforms ITO. Here the authors review recent work on a novel graphene-based conductor with sheet resistance as low as 8.8 / and 84% optical transmission. This material is obtained by ferric chloride (Fecl3) intercalation into few-layer-graphene (FLG), giving rise to a new system which is the best known flexible and transparent electricity conductor. Fecl3-FLG shows no significant changes in the electrical and structural properties for a long exposure to air, to high levels of humidity and at temperatures of up to 150 degrees c in atmosphere. These properties position Fecl3-FLG as a viable and attractive replacement to ITO.

关键词： indium compounds graphene devices conductors (electric) electrodes display devices photovoltaic cells visible spectra graphene-based conductor transparent electrode photovoltaics applications display applications current standard material touch screens solar cells indium tin oxide sheet resistance optical transmission visible wavelength flexible transparent conductors optical transparency mechanical flexibility mechanical strength functionalised graphene ferric chloride flexible material transparent material electrical properties structural properties ITO c

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Low pump threshold cVD graphene based passively harmonic mode-locked fibre laser

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ELEcTRONIcS LETTERS 2017年第5期53卷 330-+页

作者： chow, Kin Kee Manchester Metropolitan Univ Sch Engn John Dalton BldgChester St Manchester M1 5GD Lancs England

A low pump threshold passively harmonic mode-locked fibre laser is demonstrated. The key component is a chemical vapour deposition grown graphene saturable absorber to enable higher order harmonic mode-locking (HML) of the fibre laser with good output noise characteristics. With a relatively low pump power of 100 mW, the fibre laser generates approximate to 1 ps soliton pulses at the 21st order of HML with 40 dB of super-mode noise suppression.

关键词： fibre lasers laser mode locking laser noise optical pumping optical saturable absorption optical solitons optical harmonic generation optical pulse generation graphene c power 100 mW super-mode noise suppression soliton pulses output noise characteristics higher order HML higher order harmonic mode-locking graphene saturable absorber chemical vapour deposition passively harmonic mode-locked fibre laser low pump threshold cVD graphene

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Transmission characteristics of multi-walled carbon nanotube-based through-silicon vias considering temperature effects

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IET MIcROWAVES ANTENNAS & PROPAGATION 2017年第10期11卷 1424-1431页

作者： Su, Jinrong chen, Xinwei Han, Liping Yang, Rongcao Zhang, Wenmei Shanxi Univ Coll Phys & Elect Taiyuan 030006 Shanxi Peoples R China

In this study, a simplified temperature-dependent expression of electron mean free path (MFP) is proposed first. Then, the electrical model of multi-walled carbon nanotube bundle-based through-silicon vias (MWcNTB-TSVs) is established considering the temperature effects of the MFP, metal-oxide-semiconductor capacitance, substrate conductance and number of conducting channels of MWcNT. Based on this model, the propagation constant, forward transmission coefficient S-21 and crosstalk at different temperatures are calculated. By analysing the phase constant, the zero dispersion transmission condition is obtained. According to this condition, the guidelines on how to select the substrate in different level integrations are proposed. Furthermore, a concise formula for the equivalent conductivity of MWcNTB is proposed. Moreover, the minimum diameter of MWcNTB-TSV whose attenuation is less than that of copper-filled TSV has been deduced.

关键词： multi-wall carbon nanotubes three-dimensional integrated circuits electron mean free path crosstalk MWcNTB-based through-silicon vias considering temperature effect electron mean free path MFP TSV multiwalled carbon nanotube bundle metal-oxide-semiconductor capacitance substrate conductance propagation constant forward transmission coefficient zero dispersion transmission condition c

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Molecular dynamics study of bio-manipulation in aqueous media

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MIcRO & NANO LETTERS 2016年第1期11卷 9-14页

作者： Kheirodin, Mohsen Pishkenari, Hossein Nejat Mahboobi, Seyed Hanif Sharif Univ Technol Sch Mech Engn Nano Robot Lab Tehran Iran Univ Calif Berkeley Dept Bioengn Berkeley CA 94720 USA

Nano-manipulation is one of the most important aspects of nano-robotics and nano-assembly. The positioning process is considered by many researches to be one of the most important parts of nano-assembly, but has been poorly investigated, particularly for biologic samples. This Letter is devoted to modelling the process of positioning a biomolecule with atomic force microscopy (AFM) in an aqueous media using molecular dynamics simulations. carbon nanotube (cNT) and graphite sheet are selected as AFM tip and substrate, respectively. To consider the effects of the medium on the manipulation, several models for decreasing the calculations including implicit, coarse grained, and all-atom methods have been investigated. They examined several parameters which may affect the quality of the manipulation process such as the cNT initial position with respect to the sample and substrate, its diameter and positioning strategies (pushing or pulling). The results demonstrate that despite of the implicit solvent methods, coarse-grained model can simulate the aqueous media accurately with lower computational cost. Furthermore, pulling method with a cNT which has a larger diameter and a smaller gap with respect to the substrate is the most appropriate setting for manipulation.

关键词： molecular dynamics method atomic force microscopy carbon nanotubes nanopositioning graphite biomanipulation aqueous media nanomanipulation nanorobotics nanoassembly atomic force microscopy molecular dynamics simulations carbon nanotube graphite sheet pushing pulling c

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