Correlation Between Interfacial Electronic Structure and Mechanical Properties of ZrN–Me (Me=Ag, Au, or Pd) Nanocomposite Films

Nanocomposite films of ZrN–Me (Me=Ag, Au, or Pd) were prepared using reactive unbalanced magnetron sputtering. The hardness and elastic modulus were measured by nanoindention and were found to vary differently with composition for the three nanocomposite structures. Young’s modulus was found to decrease much more dramatically with the increase in Me content for the ZrN–Ag system. These findings were attributed to the weaker bonding mechanism at the interface between the ceramic and the metallic phases, which is more prone to grain-boundary sliding as shown using first-principles calculations of the electronic structure at the interface for the three systems

Real-time Spectroscopic Ellipsometry Study of Ultrathin Diffusion Barriers for Integrated Circuits

The objective of this work is to monitor the growth process and the thermal stability of ultrathin tantalum nitride barrier nanostructures against copper diffusion in integrated circuits using real-time spectroscopic ellipsometry (RTSE). Single layers of copper and bilayer films of copper and tantalum nitride were produced on Si(111) substrates using unbalanced magnetron sputtering. The RTSE data was simulated using the Bruggeman effective medium approximation and a combined Drude-Lorentz model to obtain information about the growth process, film architecture, interface quality, and the conduction electron transport properties for these structures. The results deduced from the RTSE were verified by characterizing the structural and the chemical properties of the fabricated films using x-ray diffraction, Auger electron spectroscopy, and Rutherford backscattering. The effectiveness of the tantalum nitride barrier to stop the diffusion of copper into silicon was evaluated, monitoring their optical properties when annealed at 720 degreesC. The dielectric function of the films changed from a metallic to an insulating character when the diffusion proceeded. Also, the RTSE provided valuable information about the microstructure and the kinetics of the phase transformations that occur during heat treatment. (C) 2004 American Institute of Physics

Multi-Scale Modeling of Mechanobiological Behavior of Bone

The simulation and theoretical or numerical predictive modeling of the development and growth of biological tissues mainly in the case of bone is a complicated task. As a result, many and various knowledge tools required (experimental, theoretical and numerical) are not yet mastered and even discovered. We will cite here some techniques and methods as well as results specific to the multi-scale numerical modeling methodology, and multiphysics using finite element coupling with neural network computation of biological tissues applied to the predictive behavior of cortical bone based of the microstructure of their local constituents and their reconstruction according to local mechanobiology. It follows that additional work is necessary to give more precision on the different models, the considered approaches show their potential utility to understand this behavior in terms of biological evolutions as well as the subsequent use in medical applications

Chemokine and Chemokine Receptor Gene Polymorphism in Tunisian Hemodialysis Patients with HCV Infection

Introduction: Our aim was to investigate the possibility of a significant relationship between chemokines and chemokine receptor genes polymorphisms and the spontaneous clearance or the persistence of HCV infection. Methods: A total of 96 hemodialysis (HD) patients infected with HCV were classified into two groups: G1 included 73 patients with persistently positive HCV-RNA and G2 included 23 HD patients who have spontaneously eliminated the virus. The control group consisted of 170 healthy blood donors. All subjects were genotyped for CCR5 Δ32, CCR5 (-59029) A/G, CCR2 (64Ile) and MCP-1(-2518) A/G gene polymorphisms. Results: Our results showed statistically significant increased frequencies of the CCR2 (64Ile) and the (-59029) CCR5 A alleles in patients infected with HCV (22.1% and 35.9%) compared to G1 (24.3% and 40.6%) and compared to controls (14.4% and 20%). We also observed a lower frequency of the MCP-1 G allele and a greater frequency of the CCR5Δ32 variant in G2 (15.2% and 6.5%) compared to G1 (22.6% and 1.4%) that was not statistically significant. However, adjustment for known covariates (age, gender and HCV genotypes) didn’t confirm the results of univariate analysis. Conclusion: In conclusion, our study suggests a possible role for some of the studied chemokines polymorphisms in the spontaneous clearance or persistence of HCV infection in Tunisian population. These results should be further investigated by a prospective cohort studies and large population-based studies.Keywords: Chemokines; Receptors; Hepatitis C virus; Spontaneous Clearance; Polymorphisms

Optical and photoelectronic properties of a new material:Optoelectronic application

With the aim of studying the optical, electrochemical, and electronic properties of a new porphyrin-based material, we have synthesized a new porphyrinic complex, namely the (4,4$^{\prime}$-bipyridine)(meso-tetratrifluoromethylphenylporphyrinato)zinc(II) 4,4$^{\prime}$-bipyridine disolvate dihydrate complex with the formula [Zn(TFMPP)(4,4$^{\prime}$-bipy)]${\cdot }$2(4,4$^{\prime}$-bipy)${\cdot }$2H2O (I). This species is characterized by single-crystal X-ray molecular structure. The optical study is performed by UV–visible absorption and fluorescence spectroscopy. The fluorescence intensity presents an emission in the UV–visible range, indicating that this compound can be used as an optoelectronic material. The optical energy gap is 1.95 eV, and the current–voltage characteristics and impedance spectroscopy measurements have been studied to define the electronic properties of the zinc (II) porphyrin complex. The barrier height ${\phi }_{\mathrm{b}}$ is calculated, and the space-charge limited current mechanism is found to control the conductance. The results from the electronic study confirm that our porphyrin derivative can be used for various optoelectronic applications

Design, Synthesis and Discovery of N,N'-Carbazoyl-aryl-urea Inhibitors of Zika NS5 Methyltransferase and Virus Replication

The recent outbreaks of Zika virus (ZIKV) infection worldwide make the discovery of novel antivirals against flaviviruses a research priority. This work describes the identification of novel inhibitors of ZIKV through a structure‐based virtual screening approach using the ZIKV NS5‐MTase. A novel series of molecules with a carbazoyl‐aryl‐urea structure has been discovered and a library of analogues has been synthesized. The new compounds inhibit ZIKV MTase with IC50 between 23–48 μM. In addition, carbazoyl‐aryl‐ureas also proved to inhibit ZIKV replication activity at micromolar concentration

Bimodal Effect on Pancreatic β-Cells of Secretory Products From Normal or Insulin-Resistant Human Skeletal Muscle

OBJECTIVE: Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) beta-cells. RESEARCH DESIGN AND METHODS: Human skeletal muscle cells were cultured for up to 24 h with tumor necrosis factor (TNF)-alpha to induce insulin resistance, and mRNA expression for cytokines was analyzed and compared with controls (without TNF-alpha). Conditioned media were collected and candidate cytokines were measured by antibody array. Human and rat primary beta-cells were used to explore the impact of exposure to conditioned media for 24 h on apoptosis, proliferation, short-term insulin secretion, and key signaling protein phosphorylation and expression. RESULTS: Human myotubes express and release a different panel of myokines depending on their insulin sensitivity, with each panel exerting differential effects on beta-cells. Conditioned medium from control myotubes increased proliferation and glucose-stimulated insulin secretion (GSIS) from primary beta-cells, whereas conditioned medium from TNF-alpha-treated insulin-resistant myotubes (TMs) exerted detrimental effects that were either independent (increased apoptosis and decreased proliferation) or dependent on the presence of TNF-alpha in TM (blunted GSIS). Knockdown of beta-cell mitogen-activated protein 4 kinase 4 prevented these effects. Glucagon-like peptide 1 protected beta-cells against decreased proliferation and apoptosis evoked by TMs, while interleukin-1 receptor antagonist only prevented the latter. CONCLUSIONS: Taken together, these data suggest a possible new route of communication between skeletal muscle and beta-cells that is modulated by insulin resistance and could contribute to normal beta-cell functional mass in healthy subjects, as well as the decrease seen in type 2 diabetes