bluuebunny/crossref_metadata_2025 huggingface dataset:
NOS isoform‐specific regulation of basal but not exercise‐induced mitochondrial biogenesis in mouse skeletal muscle
Authors: Wadley G. D. , Choate J. , McConell G. K.
Published: October 2007

Nitric oxide is a potential regulator of mitochondrial biogenesis. Therefore, we investigated if mice deficient in endothelial nitric oxide synthase (eNOS−/−) or neuronal NOS (nNOS−/−) have attenuated activation of skeletal muscle mitochondrial biogenesis in response to exercise. eNOS−/−, nNOS−/− and C57Bl/6 (CON) mice (16.3 ± 0.2 weeks old) either remained in their cages (basal) or ran on a treadmill (16 m min−1, 5% grade) for 60 min (n= 8 per group) and were killed 6 h after exercise. Other eNOS−/−, nNOS−/− and CON mice exercise trained for 9 days (60 min per day) and were killed 24 h after the last bout of exercise training. eNOS−/− mice had significantly higher nNOS protein and nNOS−/− mice had significantly higher eNOS protein in the EDL, but not the soleus. The basal mitochondrial biogenesis markers NRF1, NRF2α and mtTFA mRNA were significantly (P< 0.05) higher in the soleus and EDL of nNOS−/− mice whilst basal citrate synthase activity was higher in the soleus and basal PGC‐1α mRNA higher in the EDL. Also, eNOS−/− mice had significantly higher basal citrate synthase activity in the soleus but not the EDL. Acute exercise increased (P< 0.05) PGC‐1α mRNA in soleus and EDL and NRF2α mRNA in the EDL to a similar extent in all genotypes. In addition, short‐term exercise training significantly increased cytochrome c protein in all genotypes (P< 0.05) in the EDL. In conclusion, eNOS and nNOS are differentially involved in the basal regulation of mitochondrial biogenesis in skeletal muscle but are not critical for exercise‐induced increases in mitochondrial biogenesis in skeletal muscle.
Synaptic heterogeneity between mouse paracapsular intercalated neurons of the amygdala
Authors: Geracitano Raffaella , Kaufmann Walter A. , Szabo Gabor , Ferraguti Francesco , Capogna Marco
Published: October 2007

GABAergic medial paracapsular intercalated (Imp) neurons of amygdala are thought of as playing a central role in fear learning and extinction. We report here that the synaptic network formed by these neurons exhibits distinct short‐term plastic synaptic responses. The success rate of synaptic events evoked at a frequency range of 0.1–10 Hz varied dramatically between different connected cell pairs. Upon enhancing the frequency of stimulation, the success rate increased, decreased or remained constant, in a similar number of cell pairs. Such synaptic heterogeneity resulted in inhibition of the firing of the postsynaptic neurons with different efficacies. Moreover, we found that the different synaptic weights were mainly determined by diversity in presynaptic release probabilities rather than postsynaptic changes. Sequential paired recording experiments demonstrated that the same presynaptic neuron established the same type of synaptic connections with different postsynaptic neurons, suggesting the absence of target‐cell specificity. Conversely, the same postsynaptic neuron was contacted by different types of synaptic connections formed by different presynaptic neurons. A detailed anatomical analysis of the recorded neurons revealed discrete and unexpected peculiarities in the dendritic and axonal patterns of different cell pairs. In contrast, several intrinsic electrophysiological responses were homogeneous among neurons, and synaptic failure counts were not affected by presynaptic cannabinoid 1 or GABAB receptors. We propose that the heterogeneous functional connectivity of Imp neurons, demonstrated by this study, is required to maintain the stability of firing patterns which is critical for the computational role of the amygdala in fear learning and extinction.
pH dependence of melanoma cell migration: protons extruded by NHE1 dominate protons of the bulk solution
Authors: Stüwe Laura , Müller Markus , Fabian Anke , Waning Judith , Mally Sabine , Noël Josette , Schwab Albrecht , Stock Christian
Published: October 2007

Migration and morphology of human melanoma cells (MV3) depend on extracellular pH (pHe) and the activity of the Na+/H+ exchanger NHE1. To distinguish effects of NHE1 activity per se from effects of pHe we compared an NHE1‐deficient mutant with rescued and wild‐type cells. Time lapse video microscopy was used to investigate migratory and morphological effects caused by pHe and NHE1 activity, and a membrane‐bound fluorescein conjugate was employed for ratiometric pH measurements at the outer leaflet of the cell membrane. As long as NHE1 remained inactive due to deficiency or inhibition by cariporide (HOE642) neither migration nor morphology was affected by changes in pHe. Under these conditions pH at the outer leaflet of the plasma membrane was uniform all over the cell surface. The typical pH dependence of MV3 cell migration and morphology could be reconstituted by restoring NHE1 activity. At the same time the proton gradient at the outer leaflet of the plasma membrane with the higher proton concentration at the leading edge and the lower one at the cell rear was re‐established as well. Hence, NHE1 activity generates a proton gradient at the cell surface accompanied by the cells' ability to respond to changes in pHe (bulk pH). We conclude that NHE1 activity contributes to the generation of a well‐defined cell surface pH by creating a proton gradient at the outer leaflet of the plasma membrane that is needed for (i) the development of a variety of morphologies including a distinct polarity and (ii) migration. A missing proton gradient at the cell surface cannot be compensated for by varying pHe.
Modeling and Analysis of Functionally Graded Materials and Structures
Authors: Birman Victor , Byrd Larry W.
Published: October 2007

This paper presents a review of the principal developments in functionally graded materials (FGMs) with an emphasis on the recent work published since 2000. Diverse areas relevant to various aspects of theory and applications of FGM are reflected in this paper. They include homogenization of particulate FGM, heat transfer issues, stress, stability and dynamic analyses, testing, manufacturing and design, applications, and fracture. The critical areas where further research is needed for a successful implementation of FGM in design are outlined in the conclusions.
Effect of interface treatment with assisted ion beam on Mo-Si multilayer formation for mask blanks for extreme ultraviolet lithography
Authors: Hiruma Kenji , Miyagaki Shinji , Yamaguchi Atsuko , Nishiyama Iwao
Published: October 2007

To reduce the surface roughness of a substrate for mask blanks for extreme ultraviolet (EUV) lithography, the layers of a Mo-Si multilayer structure being deposited by magnetron sputtering were treated with an assisted ion beam. The effectiveness was analyzed by atomic force microscopy, x-ray reflection diffraction, EUV reflectivity measurements, and transmission electron microscopy (TEM). An interface analysis was performed using software that extracts the roughness profile of a Mo/Si interface from a TEM image. The results showed that the treatment produced a large reduction in both interface and surface roughness, resulting in a multilayer with better EUV performance than one formed without such treatment.
Fabrication and characterization of a field emission display prototype for indoor giant display application
Authors: Zhou T. T. , She J. C. , Chen Jun , Deng S. Z. , Xu N. S.
Published: October 2007

The authors report the fabrication and characterization of a 4.5in. field emission display (FED) prototype. The FED prototype consists of 14×14 matrix addressable pixels. The pixel is 5mm in diameter. The characteristics including current-voltage properties, current stability, brightness, and image quality of the display prototype were characterized. The average static brightness of the display prototype is 2500cd∕m2. Characters were displayed in a scanning pulsed driving mode. The adjacent pixels are tangent to each other, making continuous display feature. The results show that the FED prototype has promising potential for high-resolution giant display application.
On the photoresist stripping and damage of ultralow k dielectric materials using remote H2- and D2-based discharges
Authors: Stueber Guido J. , Oehrlein Gottlieb S. , Lazzeri P. , Bersani M. , Anderle M. , Busch Eric , McGowan Richard
Published: October 2007

Blanket films of ultralow dielectric constant (ULK) materials and 193nm photoresist films have been processed downstream from hydrogen and deuterium-based discharges produced using an inductively coupled plasma reactor. Photoresist ashing rates and ULK modifications have been determined as a function of process parameters. The explored ULK materials differed widely in porosity and carbon content. The effect of processing time, substrate temperature (200–300°C), and gas composition on the surface and bulk chemical composition of ULK materials was monitored and quantified by ex situ ellipsometry and time-of-flight secondary ion mass spectrometry (SIMS). The stripping rates of 193nm photoresist films were found to strongly depend on processing temperature and only weakly on the nature of the H2/additive gas mixture. The authors found that hydrogen (or deuterium) fully penetrates the high porosity ULK layer, whereas for low porosity materials, such penetration is limited to a 50nm near-surface region. SIMS measurements also reveal that H2 (D2) diffusion into carbon-rich ULK layers can cause substantial carbon depletion throughout the penetration region. ULK damage values increase with temperature and injection of gas additives such as argon, helium, and nitrogen to H2 or D2 process gases. For each ULK material, the amount of damage depends on the gas mixing ratio; in general, high percentages of nitrogen in H2∕N2 (or D2∕N2) mixtures cause the most damage. Overall, the results demonstrate that ULK ashing damage depends strongly on both ULK material properties and H2-based plasma process parameters. In addition, the authors observed in this work a kinetic isotope effect for stripping of 193nm photoresist films in H2∕D2∕N2-based discharges. For given ashing process conditions, the photoresist ashing rate decreases by a factor of 1.414 (or square root of 2) in D2 plasma compared to H2 plasma. This can be explained by the influence of the H or D mass on the chemical reaction rate through a change in the frequency of nuclear vibrations of the reacting atoms. The presence of the kinetic isotope effect for gas mixtures provides unambiguous evidence of the rate-limiting role of atomic hydrogen in the fundamental etching reaction. Simultaneously processed ULK materials showed minor film thickness changes (<10nm) in H2 or D2 discharges, and the ULK damage level does not reflect a kinetic isotope effect. Therefore the H∕D isotope effect can be used to separate H2∕D2 associated ashing and etching processes from other chemistries or mechanisms.
Effects of phase of underlying W film on chemical vapor deposited-W film growth and applications to contact-plug and bit line processes for memory devices
Authors: Kim Soo-Hyun , Kim Jeong-Tae , Kwak Nohjung , Kim Jinwoong , Yoon Tae-Sik , Sohn Hyunchul
Published: October 2007

This article presents the effects of phases of underlying nucleation layers prepared using two different reaction schemes, one is with B2H6 and WF6 and the other with SiH4 and WF6, on the properties of chemical vapor deposited (CVD)-tungsten (W) thin film. From the x-ray diffractometry and transmission electron microscopy analysis, the B2H6-based nucleation layer was found to form as a poorly crystallized metastable β-phase W while SiH4-based one as a well-crystallized equilibrium α phase. The subsequently grown CVD-W film, as deposited with α phase, has significantly larger grains and, consequently, mitigated the increase of CVD-W resistivity due to size effect as well as lower resistivity on the B2H6-based nucleation layer than on SiH4-based one. CVD-W film on the B2H6-based nucleation layer integrated on memory devices disclosed the improved electrical properties of interconnection such as lowered contact resistance at the metal line to bit line contact, lowered bit line resistance, and reduced parasitic capacitance. These improved electrical properties are explained with the enlarged grain size of CVD-W film on the B2H6-based nucleation layer compared to that on the SiH4-based one, which is determined by the nucleation and growth behaviors on each nucleation layer.
Optical improvement of photonic devices fabricated by Ga+ focused ion beam micromachining
Authors: Tao Hai-Hua , Ren Cheng , Feng Shuai , Liu Ya-Zhao , Li Zhi-Yuan , Cheng Bing-Ying , Zhang Dao-Zhong , Jin Ai-Zi
Published: October 2007

The authors propose a novel post-focused-ion-beam (FIB) treatment method to improve the optical properties of photonic devices fabricated by the Ga+ FIB technique on the silicon substrate with low temperature liquid annealing process. A conventional micrometric ridge waveguide is first fabricated and then annealed to roughly detect the improvement of its optical properties. Then a nanometric 12-fold photonic quasicrystal waveguide is designed to further study its topography variation as well as the subtle influence on its optical properties with different post-FIB treatments. By comparing the experimental results with the theoretical results that are made by means of the three-dimensional finite-difference time-domain method, the authors find that the proposed low temperature liquid annealing method can efficiently improve the optical properties of photonic devices by decreasing Ga+ contamination, removing redeposited Si–SiO2 composites, and restoring damaged silicon lattice structures caused by Ga+ bombardment in the FIB micromachining.
Electron emission characteristics of sol-gel (Ba0.67Sr0.33)TiO3 thin film coated silicon tips
Authors: Gurbuz Y. , Kang W. P. , Davidson J. L. , Tan O. K. , Zhu W. G. , Li Q. , Xu J. F.
Published: October 2007

Field emission characteristics of sol-gel (Ba0.67Sr0.33)TiO3 (BST) ferroelectric thin film coated silicon emitters have been systemically investigated. The effects of BST coating, BST annealing temperature, and biasing at BST-silicon junction on field emission characteristics of BST coated silicon tips have been studied. The authors have found that field emission characteristics of silicon tips can be significantly improved by BST coating. The turn-on electric field required between the silicon tips and the anode significantly reduced from 70to4–20V∕μm by BST coating. The theoretical studies have shown that the improved emission characteristics by BST coating may be attributed to the lower electron affinity and the lower work function properties of BST material. Emission stability was also improved by BST coating. BST coated silicon emitter has a relatively stable emission current with 20% fluctuation compared to 50% current fluctuation of uncoated silicon tips. It was also found that the emission characteristics of BST coated silicon tips strongly depended on BST annealing temperature. The samples with 750°C BST annealing temperature were found to have the best emission characteristics with low turn-on electric field of 4–9V∕μm. A higher annealing temperature results in higher activation of ionic conduction, increasing carrier concentration, raising the Fermi level toward the conduction band, and thus reducing the effective work function. Finally, the electron field emission from BST coated silicon tips was improved significantly by the positive bias on BST-silicon junction. The theoretical studies have shown that the effective work function is reduced with a positive bias on BST-silicon junction and hence the turn-on electric field is significantly reduced by the bias on BST-silicon junction.
Interpretation of atomic friction experiments based on atomistic simulations
Authors: Wyder U. , Baratoff A. , Meyer E. , Kantorovich L. N. , David J. , Maier S. , Filleter T. , Bennewitz R.
Published: October 2007

Atomic stick-slip experiments on the KBr(100) surface are analyzed using classical zero temperature atomistic simulations. Three different tip models exhibiting atomic stick-slip movement are studied in comparison with the experimental data and the Tomlinson model. The implications of a compliant tip apex for the stick-slip process and the dissipation pathways are discussed.
Influence of halo implant on leakage current and sheet resistance of ultrashallow p-n junctions
Authors: Faifer V. N. , Schroder D. K. , Current M. I. , Clarysse T. , Timans P. J. , Zangerle T. , Vandervorst W. , Wong T. M. H. , Moussa A. , McCoy S. , Gelpey J. , Lerch W. , Paul S. , Bolze D. , Halim J.
Published: October 2007

Sheet resistance and leakage current density of spike rapid thermal processed, millisecond flash annealed, and chemical vapor deposition (CVD) grown ultrashallow junctions (USJs) are compared with the contactless junction photovoltage technique for measurement of sheet resistance and leakage current (RsL) and four-point probe (4PP) techniques. A significant leakage current increase for USJs formed in halo-implanted profiles is explained by high electron and hole recombination generation in the near-surface end-of-range damaged layer enhanced by trap-assisted tunneling. The reduced thermal budget of millisecond annealing allows junction formation with reduced dopant diffusion and lower sheet resistance. However, when strong halo doping is employed, there is a significant increase in junction leakage current relative to that for junctions formed by spike annealing. This rise in leakage current can be reduced by annealing the halo implants before implanting the USJ or by lowering the halo implant dose. USJs grown with CVD demonstrate low leakage current due to localization of recombination centers at the edge of the depletion layer where recombination (generation) is low. This study demonstrates the importance of characterizing USJs formed in halo profile using the contactless RsL technique and highlights the limitations of contact probes, such as four-point probes, for characterization of advanced ultralarge scale integrated junctions.
Solutions to a proximity effect in high resolution electron beam induced deposition
Authors: van Dorp W. F. , Lazar S. , Hagen C. W. , Kruit P.
Published: October 2007

A new type of proximity effect in electron beam induced deposition (EBID) is presented. Proximity effects are well known in resist based electron beam lithography (EBL), where they present themselves as an extra and unintentional exposure of the resist layer surrounding the irradiated areas. Several types of proximity effects have already been reported for EBID, which are of a different nature. The authors report a proximity effect where the amount of deposited mass increases with each new line that is deposited. This effect occurs when parallel lines are deposited at a spacing close to the width of the lines. The increase in deposition rate was found to be dependent on the angle between the irradiated target and the incident electron beam. Results from a simulation based on this model qualititatively show the same trend. A successful strategy for reducing the effect is presented.
Bright-field transmission imaging of carbon nanofibers on bulk substrate using conventional scanning electron microscopy
Authors: Suzuki Makoto , Ngo Quoc , Kitsuki Hirohiko , Gleason Kristofer , Ominami Yusuke , Yang Cary Y. , Yamada Toshishige , Cassell Alan M. , Li Jun
Published: October 2007

The authors present scanning transmission electron microscopy (STEM) of carbon nanofibers (CNFs) on a bulk substrate using conventional scanning electron microscopy (SEM) without specimen thinning. By utilizing the electron beam tilted >85° from the substrate normal, bright-field STEM contrast is obtained for the CNFs on substrate with conventional SEM. Analysis of the observed contrast using Monte Carlo simulation shows that the weakly scattered electrons transmitted from the CNF are selectively enhanced by the largely tilted substrate and result in the observed STEM contrast. This mechanism provides a useful STEM imaging technique to investigate the internal structure of materials on bulk substrates without destructive specimen thinning.
Ga
2
O
3
grown on GaAs by molecular beam epitaxy for metal oxide semiconductor field effect transistors
Authors: Holland M. , Stanley C. R. , Reid W. , Hill R. J. W. , Moran D. A. J. , Thayne I. , Paterson G. W. , Long A. R.
Published: October 2007

Molecular beam epitaxy has been used to deposit Ga2O3 onto GaAs(001) to form a III-V/oxide interface. Photoluminescence is used to monitor the interface quality and to compare these films with samples known to have a low interface state density and an unpinned Fermi level. An additional flux of molecular oxygen has been used during oxide growth, and the impact on growth rate is reported. A rf plasma source is shown to produce mainly neutral atomic oxygen. Atomic oxygen has a significant impact on the oxide growth mechanism and interface quality. The performance of metal oxide semiconductor field effect transistors fabricated from GaAs structures with their surface unpinned by Ga2O3 is discussed briefly.
Possibility of constructing microwave antenna with carbon nanotubes
Authors: Zhu Q. , Wu L. , Sheng S. , Mei Z. C. , Liu W. F. , Cai W. L. , Yao L. Z.
Published: October 2007

The distribution of electrons on a carbon nanotube (CNT) under microwave excitation is analyzed here. Numerical results demonstrate that electrons on CNTs are oscillating under the microwave excitation, which means that the electrons can radiate microwaves with the same frequency. The length of CNTs required for microwave radiation is estimated. Both results reveal that it is possible to construct a microwave antenna with carbon nanotubes or nanotube arrays.
Plasma treatment on plastic substrates for liquid-phase-deposited SiO2
Authors: Yeh Chih-Chieh , Lin Yu-Ju , Lin Shun-Kuan , Wang Yeong-Her , Chung Sheng-Feng , Huang Li-Ming , Wen Ten-Chin
Published: October 2007

The liquid-phase deposition method for growing silicon dioxide interlayers on O2∕Ar plasma pretreatment plastic substrates is investigated. The authors found that the ratio of COO (288.9eV) to CH2(284.5eV) increases with the O2∕Ar plasma pretreatment as indicated by x-ray photoelectron spectroscopy. Upon treatment, the interlayer on the plastic substrate is grown, and the quality of the film on the substrate with or without plasma pretreatment is examined by using scanning electron microscopy, etching rate of the oxide layer by dilute HF solution, and surface leakage current measurement. Pentacene-based organic thin-film transistors on dielectric layers are demonstrated. Finally, they also found that this coating can enhance optical transmittance, as demonstrated by ultraviolet-visible spectroscopy measurement.
Room temperature InGaSb quantum well microcylinder lasers at 2μm grown monolithically on a silicon substrate
Authors: Yang Tian , Lu Ling , Shih Min-Hsiung , O’Brien J. D. , Balakrishnan Ganesh , Huffaker D. L.
Published: October 2007

Fabrication of microcylinder laser cavities in III-Sb material on a silicon substrate is reported. Room temperature lasing near 2μm wavelength under optical pumping conditions is demonstrated in the microcylinders with InGaSb quantum wells. The III-Sb material is grown monolithically on a silicon substrate. High quality epitaxy is enabled by an interfacial misfit array.
Temperature influence and hot electrons in field electron emission from composite layers deposited by air plasma spraying of powders and suspensions
Authors: Znamirowski Z. , Czarczyński W. , Pawlowski L. , Wojnakowski A.
Published: October 2007

A temperature dependence of field electron emission from composite layers has been investigated. Air plasma spraying associated with laser engraving and suspension plasma spraying has been used for preparation of composite field electron emitters. The deposited materials were fine sized TiO2 and TiO2∕Al2O3 powders. The sprayed titanium oxide layers contained rutile, anatase, and Magneli phases as well as alumina and alumina-titania spinel. Field emission from these layers was strongly influenced by the emitter temperature. A decrease of emission with temperature rise was observed. This effect has been explained as a result of rutile grain permittivity and conductivity increase with temperature. Model calculations supported this explanation. The plots of low-level current emission as a function of temperature have been used for identification of emission mechanism in this range. The presence of low-current tail in Fowler-Nordheim plot has been attributed to hot electrons. An absence of such tail should indicate a metal-like conduction mechanism in the emitting layer. As the penetration of external electric field into the bulk of emitter material creates conditions for generation of hot electrons, the temperature dependence of electron emission current may be used for indication of carrier transport mechanism in the composite layers.
Etching mechanisms of HfO2, SiO2, and poly-Si substrates in BCl3 plasmas
Authors: Sungauer E. , Pargon E. , Mellhaoui X. , Ramos R. , Cunge G. , Vallier L. , Joubert O. , Lill T.
Published: October 2007

B Cl 3 based plasmas exhibit promising plasma chemistries to etch high-k materials and, in particular, HfO2, with a high selectivity over SiO2 and Si substrates. The authors report on the mechanisms involved in the etching of HfO2, SiO2, and poly-Si substrates in BCl3 plasmas. X-ray photoelectron spectroscopy analyses help in understanding the mechanism driving the high etch selectivity between HfO2 and silicon-containing substrates. The ion energy plays an important role in the etching mechanisms since it controls a transition between a BCl-like deposition on the substrate and its etching by ionic bombardment. The ion energy threshold above which etching occurs is different from one substrate to another, being lower for HfO2 than for Si substrates. Indeed, BClx deposition forms more easily on poly-Si or SiO2 rather than on HfO2 surfaces, because boron reacts with Si atoms to form Si–B bonds initiating the growth of BClx polymer on Si-containing surfaces, while on HfO2 surfaces, boron is directly involved in the etching and reacts with oxygen to form volatile BOCl etch products.
Transport behavior of atomic layer deposition precursors through polymer masking layers: Influence on area selective atomic layer deposition
Authors: Sinha Ashwini , Hess Dennis W. , Henderson Clifford L.
Published: October 2007

Sorption and diffusion of precursors through polymer layers were considered as limitations to the successful implementation of a polymer film-based masking approach to area selective atomic layer deposition techniques (ASALDT). Quartz crystal microbalance studies were used to estimate solubility and diffusivity of ALD precursors through supported thin polymer films at elevated temperatures. Specifically, measurements have been performed to estimate the solubility of water in polyhydroxystyrene, polymethylmethacrylate (PMMA), and hexafluoroisopropylalcohol polynorbornene. In addition, diffusion coefficients and solubilities of titanium tetrachloride (TiCl4) and titanium isopropoxide [Ti(ipr)4] through PMMA have also been determined. The results suggest that polymer films exhibit insignificant water uptake at high temperature (∼160°C) and, hence, sorption of water into polymer films does not pose limitations to polymer masking-based ASALDT. Diffusion coefficient measurements of metal precursors account for the role of precursor size in determining the minimum polymer masking layer thickness for a successful ASALDT process.
Microcontact printing pattern as a mask for chemical etching: A scanning photoelectron microscopy study
Authors: Wu Yi-Te , Liao Jiunn-Der , Weng Chih-Chiang , Chen Chia-Hao , Wang Ming-Chen , Zharnikov Michael
Published: October 2007

Synchrotron-based scanning photoelectron spectromicroscopy and microspectroscopy were used to monitor the outcome of the etching process involving the transfer of a lithographic pattern produced by microcontact printing (μCP) of self-assembled monolayers (SAMs) to the underlying metal (gold) substrate. As a test system, octadecanethiolate (ODT) SAMs on gold substrates were chosen. The μCP ODT SAMs were found to protect the underlying gold against the wet-chemical etching, ensuring the effective transfer of the μCP pattern to the substrate. These SAMs exhibited only a slight degradation upon their exposure to the Au-etching solution. In contrast, a significant degradation of the edges of the printed features was observed. This degradation was predominantly related to a lateral diffusion of the active etching agents across these edges, along the SAMs-Au interface. This process can result in a blurring and narrowing of the printing features of a μCP SAM pattern at its transfer to the underlying substrate.
Telomeric Repeat–Containing RNA and RNA Surveillance Factors at Mammalian Chromosome Ends
Authors: Azzalin Claus M. , Reichenbach Patrick , Khoriauli Lela , Giulotto Elena , Lingner Joachim
Published: October 2007

Telomeres, the DNA-protein complexes located at the end of linear eukaryotic chromosomes, are essential for chromosome stability. Until now, telomeres have been considered to be transcriptionally silent. We demonstrate that mammalian telomeres are transcribed into telomeric repeat–containing RNA (TERRA). TERRA molecules are heterogeneous in length, are transcribed from several subtelomeric loci toward chromosome ends, and localize to telomeres. We also show that suppressors with morphogenetic defects in genitalia (SMG) proteins, which are effectors of nonsense-mediated messenger RNA decay, are enriched at telomeres in vivo, negatively regulate TERRA association with chromatin, and protect chromosome ends from telomere loss. Thus, telomeres are actively transcribed into TERRA, and SMG factors represent a molecular link between TERRA regulation and the maintenance of telomere integrity.
TOPOLOGICAL ZERO-THICKNESS COSMIC STRINGS
Authors: DUAN YI-SHI , CAO ZHEN-BIN
Published: October 2007

In this paper, based on the gauge potential decomposition and the ϕ-mapping theories, we study the topological structures and properties of the cosmic strings that arise in the Abelian–Higgs gauge theory in the zero-thickness limit. After a detailed discussion, we conclude that the topological tensor current introduced in our model is a better and more basic starting point than the generally used Nambu–Goto effective action for studying cosmic strings.
IMPLICATIONS OF MEASURED PROPERTIES OF THE MIXING MATRIX ON MASS MATRICES
Authors: CHATURVEDI S. , GUPTA V. , SÁNCHEZ-COLÓN G.
Published: October 2007

It is shown how the two experimentally measurable properties of the mixing matrix V, the asymmetry Δ(V) = |V12|2 - |V21|2 of V with respect to the main diagonal and the Jarlskog invariant [Formula: see text], can be exploited to obtain constraints on possible structures of mass matrices in the quark sector. Specific mass matrices are examined in detail as an illustration.
STATIONARY VACUUM HYPER-CYLINDRICAL SOLUTION IN 4+1 DIMENSIONS
Authors: LEE JUNGJAI , KIM HYEONG-CHAN
Published: October 2007

We find a (4+1)-dimensional stationary vacuum hyper-cylindrical solution which is spherically symmetric in three dimensions and invariant under the translation along the fifth coordinate. The solution is characterized by three parameters, mass, tension, and conserved momentum along the fifth coordinate. The metric is locally equivalent to the known static solution. We briefly discuss its physical properties.
INFRARED-SUPPRESSED GLUON PROPAGATOR IN 4D YANG–MILLS THEORY IN A LANDAU-LIKE GAUGE
Authors: CUCCHIERI ATTILIO , MAAS AXEL , MENDES TEREZA
Published: October 2007

The infrared behavior of the gluon propagator is directly related to confinement in QCD. Indeed, the Gribov–Zwanziger scenario of confinement predicts an infrared vanishing (transverse) gluon propagator in Landau-like gauges, implying violation of reflection positivity and gluon confinement. Finite-volume effects make it very difficult to observe (in the minimal Landau gauge) an infrared suppressed gluon propagator in lattice simulations of the four-dimensional case. Here we report results for the SU(2) gluon propagator in a gauge that interpolates between the minimal Landau gauge (for gauge parameter λ equal to 1) and the minimal Coulomb gauge (corresponding to λ = 0). For small values of λ we find that the spatially-transverse gluon propagator D tr (0, |p|), considered as a function of the spatial momenta |p|, is clearly infrared suppressed. This result is in agreement with the Gribov–Zwanziger scenario and with previous numerical results in the minimal Coulomb gauge. We also discuss the nature of the limit λ→0 (complete Coulomb gauge) and its relation to the standard Coulomb gauge (λ = 0). Our findings are corroborated by similar results in the three-dimensional case, where the infrared suppression is observed for all considered values of λ.
THE RARITA–SCHWINGER FIELD: RENORMALIZATION AND PHENOMENOLOGY
Authors: KALOSHIN A. E. , LOMOV V. P.
Published: October 2007

We discuss renormalization of propagator of interacting Rarita–Schwinger field. Spin-3/2 contribution after renormalization takes usual resonance form. For nonleading spin-1/2 terms we found procedure, which guarantees absence of poles in energy plane. The obtained renormalized propagator has one free parameter and is a straight generalization of the famous free propagator of Moldauer and Case. Application of this propagator for production of Δ++(1232) in π+ p →π+p leads to good description of total cross-section and to reasonable agreement with results of partial wave analysis.
NEW APPROACH FOR FINDING MULTIPARTITE ENTANGLED STATE REPRESENTATIONS VIA THE IWOP TECHNIQUE
Authors: FAN HONG-YI , LIU SHU-GUANG
Published: October 2007

We present a new approach to finding multipartite entangled state representation by decomposing normally ordered Gaussian-form operator in completeness relation, the technique of integration within an ordered product (IWOP) of operators is essential in this searching.
THE NLO QCD CALCULATION OF SEA QUARK DISTRIBUTIONS IN THE CORGI APPROACH, BASED ON THE CONSTITUENT QUARK MODEL
Authors: MIRJALILI A. , KESHAVARZIAN K.
Published: October 2007

Sea quark distributions in the NLO approximation, based on the phenomenological valon model or constituent quark model are analyzed. We use the parametrized inverse Mellin transform technique to perform a direct fit with available experimental data and obtain the unknown parameters of the distributions. We try to extend the calculation to the NLO approximation for the singlet and nonsinglet cases in DIS phenomena. We do also the same calculation for electron–positron annihilation. The resulting sea distributions are effectively independent of the process used. The approach of complete RG improvement (CORGI) is employed and the results are compared with the standard approach of perturbative QCD in the [Formula: see text] scheme with a physical scale. The comparisons with data are in good agreement. As is expected, the results in the CORGI approach indicate a better agreement to the data than the NLO calculation in the standard approach.
THE ELEMENTARY PARTICLES AS QUANTUM KNOTS IN ELECTROWEAK THEORY
Authors: FINKELSTEIN ROBERT J.
Published: October 2007

We explore a knot model of the elementary particles that is compatible with electroweak physics. The knots are quantized and their kinematic states are labeled by [Formula: see text], irreducible representations of SU q(2), where j = N/2, m = w/2, m′ = (r+1)/2 and (N, w, r) designate respectively the number of crossings, the writhe, and the rotation of the knot. The knot quantum numbers (N, w, r) are related to the standard isotopic spin quantum numbers (t, t3, t0) by (t = N/6, t3 = -w/6, t0 = -(r+1)/6), where t0 is the hypercharge. In this model the elementary fermions are low lying states of the quantum trefoil (N = 3) and the gauge bosons are ditrefoils (N = 6). The fermionic knots interact by the emission and absorption of bosonic knots.
MOTION OF CHARGED PARTICLES AROUND A FIVE-DIMENSIONAL ROTATING MAGNETIZED BLACK HOLE
Authors: KAYA R.
Published: October 2007

We study the effect of an external magnetic field on the stability of circular motion of charged particles in the equatorial plane of a five-dimensional rotating black hole. Using the Hamilton–Jacobi formalism, we derive the effective potential for the radial motion of test particles around a five-dimensional magnetized Myers–Perry black hole. We show that there exist stable circular orbits in equatorial planes in the background of this metric.
IMPROVED TESTS ON THE RELATIONSHIP BETWEEN THE KINETIC ENERGY OF GALAXIES AND THE MASS OF THEIR CENTRAL BLACK HOLES
Authors: FEOLI A. , MELE D.
Published: October 2007

We support, with new fitting instruments and the analysis of more recent experimental data, the proposal of a relationship between the mass of a Supermassive Black Hole (SMBH) and the kinetic energy of random motions in the host elliptical galaxy. The first results obtained in a previous paper with 13 elliptical galaxies are now confirmed by the new data and an enlarged sample. We find MBH ∝ (MGσ2/c2)β with 0.8 ≤ β ≤ 1 depending on the different fitting methods and samples used. The meaningful case β = 1 is carefully analyzed. Furthermore, we test the robustness of our relationship, including in the sample also lenticular and spiral galaxies and we show that the result does not change. Finally, we find a stronger correlation between the mass of the galaxy and the corresponding velocity dispersion that allows us to connect our relationship to the MBH ∝ σα law. With respect to this law, our relationship has the advantage of having a smaller scatter.
LOOP VARIABLE AND HOLONOMY TRANSFORMATIONS IN THE KERR–NEWMAN SPACE–TIME
Authors: GOMES DE ASSIS J. , FURTADO C. , BEZERRA V. B.
Published: October 2007

We compute the loop variable for different curves in the Kerr–Newman space–time, taking into account the appropriate modification of these quantities due to the rotation of the source. In parallel transporting of both vectors and spinors, we examine how the rotation of the charged black hole affects the holonomy for a circle on the equatorial plane.
DARK VISCOUS FLUID DESCRIBED BY A UNIFIED EQUATION OF STATE IN COSMOLOGY
Authors: REN JIE , MENG XIN-HE
Published: October 2007

We generalize the ΛCDM model by introducing a unified EOS to describe the Universe contents modeled as dark viscous fluid, motivated by the fact that a single constant equation of state (EOS) p = -p0 (p0 > 0) reproduces the ΛCDM model exactly. This EOS describes the perfect fluid term, the dissipative effect, and the cosmological constant in a unique framework and the Friedmann equations can be analytically solved. Especially, we find a relation between the EOS parameter and the renormalizable condition of a scalar field. We develop a completely numerical method to perform a χ2 minimization to constrain the parameters in a cosmological model directly from the Friedmann equations, and employ the SNe data with the parameter [Formula: see text] measured from the SDSS data to constrain our model. The result indicates that the dissipative effect is rather small in the late-time Universe.
A Role for JAK2 Mutations in Myeloproliferative Diseases
Authors: Morgan Kelly J. , Gilliland D. Gary
Published: October 2007

Myeloproliferative disorders (MPDs) are characterized by a clonal expansion of myeloid cells. Over the past two years, the identification of the JAK2V617F mutation in most cases of polycythemia vera (PV) as well as ∼50% of patients with essential thrombocythemia (ET) and idiopathic myelofibrosis (IMF) has greatly advanced our understanding of MPDs. The JAK2V617F mutation alters the JAK2 tyrosine kinase to confer constitutive activation and affect downstream signaling pathways. Data from mouse models demonstrate that the mutation is sufficient for development of PV, but additional work is needed to better understand how this allele functions in ET and IMF. Regardless of the various pathologies, the JAK2V617F discovery highlights the importance of JAK-STAT signaling in myeloid differentiation and focuses effort on developing a clinically relevant JAK2 inhibitor.
PKC Isozymes in Chronic Cardiac Disease: Possible Therapeutic Targets?
Authors: Churchill Eric , Budas Grant , Vallentin Alice , Koyanagi Tomoyoshi , Mochly-Rosen Daria
Published: October 2007

Cardiovascular disease is the leading cause of death in the United States. Therefore, identifying therapeutic targets is a major focus of current research. Protein kinase C (PKC), a family of serine/threonine kinases, has been identified as playing a role in many of the pathologies of heart disease. However, the lack of specific PKC regulators and the ubiquitous expression and normal physiological functions of the 11 PKC isozymes has made drug development a challenge. Here we discuss the validity of therapeutically targeting PKC, an intracellular signaling enzyme. We describe PKC structure, function, and distribution in the healthy and diseased heart, as well as the development of rationally designed isozyme-selective regulators of PKC functions. The review focuses on the roles of specific PKC isozymes in atherosclerosis, fibrosis, and cardiac hypertrophy, and examines principles of pharmacology as they pertain to regulators of signaling cascades associated with these diseases.
Obstructive cholestasis induces TNF-α- and IL-1β-mediated periportal downregulation of Bsep and zonal regulation of Ntcp, Oatp1a4, and Oatp1b2
Authors: Donner Markus G. , Schumacher Stephanie , Warskulat Ulrich , Heinemann Jane , Häussinger Dieter
Published: October 2007

Inverse acinar regulation of Mrp2 and 3 represents an adaptive response to hepatocellular cholestatic injury. We studied whether obstructive cholestasis (bile duct ligation) and LPS treatment affect the zonal expression of Bsep (Abcb11), Mrp4 (Abcc4), Ntcp (Slc10a1), and Oatp isoforms (Slco1a1, Slco1a4, and slco1b2) in rat liver, as analyzed by semiquantitative immunofluorescence. Contribution of TNF-α and IL-1β to transporter zonation in obstructive cholestasis was studied by cytokine inactivation. In normal liver Bsep, Mrp4, Ntcp, and Oatp1a1 were homogeneously distributed in the acinus, whereas Oatp1a4 and Oatp1b2 expression increased from zone 1 to 3. Glutamine synthetase-positive pericentral hepatocytes exhibited markedly lower Oatp1a4 expression than the remaining zone 3 hepatocytes. In cholestatic liver Bsep and Ntcp immunofluorescence in periportal hepatocytes significantly decreased to 66 ± 4% ( P < 0.01) and 67 ± 7% ( P < 0.05), whereas it was not altered in pericentral hepatocytes. Oatp1a4 was significantly induced in hepatocytes with a primarily low expression, i.e., in periportal hepatocytes and in glutamine synthetase-positive pericentral hepatocytes. Likewise, Oatp1b2 was upregulated in periportal hepatocytes. Mrp4 zonal induction was homogeneous. Inactivation of TNF-α and IL-1β prevented periportal downregulation of Bsep. Recruitment of neutrophils and polymorphonuclear cells mainly occurred in the periportal zone. Likewise, IL-1β induction was largely found periportally. No significant transporter zonation was seen following LPS treatment. In conclusion, zonal downregulation of Bsep in obstructive cholestasis is associated with portal inflammation and is mediated by TNF-α and IL-1β. Periportal downregulation of Ntcp and induction of Oatp1a4 and Oatp1b2 may represent adaptive mechanisms to reduce cholestatic injury in hepatocytes with profound downregulation of Bsep and Mrp2.
Fenofibrate inhibits intestinal Cl−secretion by blocking basolateral KCNQ1 K+channels
Authors: Bajwa Poonam J. , Alioua Abderrahmane , Lee Jimmy W. , Straus Daniel S. , Toro Ligia , Lytle Christian
Published: October 2007

Fibrates are peroxisome proliferator-activated receptor-α (PPARα) ligands in widespread clinical use to lower plasma triglyceride levels. We investigated the effect of fenofibrate and clofibrate on ion transport in mouse intestine and in human T84 colonic adenocarcinoma cells through the use of short-circuit current ( Isc) and ion flux analysis. In mice, oral administration of fenofibrate produced a persistent inhibition of cAMP-stimulated electrogenic Cl−secretion by isolated jejunum and colon without affecting electroneutral fluxes of22Na+or86Rb+(K+) across unstimulated colonic mucosa. When applied acutely to isolated mouse intestinal mucosa, 100 μM fenofibrate inhibited cAMP-stimulated Iscwithin 5 min. In T84 cells, fenofibrate rapidly inhibited ∼80% the Cl−secretory responses to forskolin (cAMP) and to heat stable enterotoxin STa (cGMP) without affecting the response to carbachol (Ca2+). Both fenofibrate and clofibrate inhibited cAMP-stimulated Iscwith an IC50∼1 μM, whereas other PPARα activators (gemfibrozil and Wy-14,643) were without effect. Membrane permeabilization experiments on T84 cells indicated that fenofibrate inhibits basolateral cAMP-stimulated K+channels (putatively KCNQ1/KCNE3) without affecting Ca2+-stimulated K+channel activity, whereas clofibrate inhibits both K+pathways. Fenofibrate had no effect on apical cAMP-stimulated Cl−channel activity. Patch-clamp analysis of HEK-293T cells confirmed that 100 μM fenofibrate rapidly inhibits K+currents associated with ectopic expression of human KCNQ1 with or without the KCNE3 β-subunit. We conclude that fenofibrate inhibits intestinal cAMP-stimulated Cl−secretion through a nongenomic mechanism that involves a selective inhibition of basolateral KCNQ1/KCNE3 channel complexes. Our findings raise the prospect of fenofibrate as a safe and effective antidiarrheal agent.
Molecular mechanisms contributing to glutamine-mediated intestinal cell survival
Authors: Larson Shawn D. , Li Jing , Chung Dai H. , Evers B. Mark
Published: October 2007

Glutamine, the most abundant amino acid in the bloodstream, is the preferred fuel source for enterocytes and plays a vital role in the maintenance of mucosal growth. The molecular mechanisms regulating the effects of glutamine on intestinal cell growth and survival are poorly understood. Here, we show that addition of glutamine (1 mmol/l) enhanced rat intestinal epithelial (RIE)-1 cell growth; conversely, glutamine deprivation increased apoptosis as noted by increased DNA fragmentation and caspase-3 activity. To delineate signaling pathways involved in the effects of glutamine on intestinal cells, we assessed activation of extracellular signal-related kinase (ERK), protein kinase D (PKD), and phosphatidylinositol 3-kinase (PI3K)/Akt, which are important pathways in cell growth and survival. Addition of glutamine activated ERK and PKD in RIE-1 cells after a period of glutamine starvation; inhibition of ERK, but not PKD, increased cell apoptosis. Conversely, glutamine starvation alone increased phosphorylated Akt; inhibition of Akt enhanced RIE-1 cell DNA fragmentation. The role of ERK was further delineated using RIE-1 cells stably transfected with an inducible Ras. Apoptosis was significantly increased following ERK inhibition, despite Ras activation. Taken together, these results identify a critical role for the ERK signaling pathways in glutamine-mediated intestinal homeostasis. Furthermore, activation of PI3K/Akt during periods of glutamine deprivation likely occurs as a protective mechanism to limit apoptosis associated with cellular stress. Importantly, our findings provide novel mechanistic insights into the antiapoptotic effects of glutamine in the intestine.