Parallel Aluminum-Cobalt Oxide Nanosheet Arrays with High-Temperature Ferromagnetism

Parallel nanomaterials possess unique properties and show potential applications in industry. Whereas, vertically aligned 2D nanomaterials have plane orientations that are generally chaotic. Simultaneous control of their growth direction and spatial orientation for parallel nanosheets remains a big challenge. Here, a facile preparation of vertically aligned parallel nanosheet arrays of aluminum-cobalt oxide is reported via a collaborative dealloying and hydrothermal method. The parallel growth of nanosheets is attributed to the lattice-matching among the nanosheets, the buffer layer, and the substrate, which is verified by a careful transmission electron microscopy study. Furthermore, the aluminum-cobalt oxide nanosheets exhibit high-temperature ferromagnetism with a 919 K Curie temperature and a 5.22 emu g⁻¹ saturation magnetization at 300 K, implying the potential applications in high-temperature ferromagnetic fields.     

Control of gold surface diffusion on si nanowires

Silicon nanowires (NW) were grown by the vapor-liquid-solid mechanism using gold as the catalyst and silane as the precursor. Gold from the catalyst particle can diffuse over the wire sidewalls, resulting in gold clusters decorating the wire sidewalls. The presence or absence of gold clusters was observed either by high angle annular darkfield scanning transmission electron microscopy images or by scanning electron microscopy. We find that the gold surface diffusion can be controlled by two growth parameters, the silane partial pressure and the growth temperature, and that the wire diameter also affects gold diffusion. Gold clusters are not present on the NW side walls for high silane partial pressure, low temperature, and small NW diameters. The absence or presence of gold on the NW sidewall has an effect on the sidewall morphology. Different models are qualitatively discussed. The main physical effect governing gold diffusion seems to be the adsorption of silane on the NW sidewalls.     

Particle sizing with a fast polar nephelometer

We reported previously the design of a polar nephelometer that uses a rotational confocal imaging setup to enable fast scanning of the scattering phase function within a field of view of 55 degrees . The full dynamic range of the detection system can be used by increasing the signal-to-noise ratio by means of averaging successive scans. The calibration of the angular response of the instrument is achieved by obtaining the transfer function of the optical detection system using Rayleigh scatterers. Accurate particle sizing of individual polystyrene spheres (ranging from 1.5 to 9 micro m in diameter) in aqueous suspension is achieved by maximizing a correlation coefficient between precalculated tables of Mie phase functions and data obtained from the polar nephelometer. Good correlation is achieved between experimental and theoretical data, proving the functioning of the instrument as a fast and convenient particle sizer.     

Estimation of polyvinyl alcohol cryogel mechanical properties with four ultrasound elastography methods and comparison with gold standard testings

Tissue-mimicking phantoms are very useful in the field of tissue characterization and essential in elastography for the purpose of validating motion estimators. This study is dedicated to the characterization of polyvinyl alcohol cryogel (PVA-C) for these types of applications. A strict fabrication procedure was defined to optimize the reproducibility of phantoms having a similar elasticity. Following mechanical stretching tests, the phantoms were used to compare the accuracy of four different elastography methods. The four methods were based on a one-dimensional (1-D) scaling factor estimation, on two different implementations of a 2-D Lagrangian speckle model estimator (quasistatic elastography methods), and on a 1-D shear wave transient elastography technique (dynamic method). Young's modulus was investigated as a function of the number of freeze-thaw cycles of PVA-C, and of the concentration of acoustic scatterers. Other mechanical and acoustic parameters-such as the speed of sound, shear wave velocity, mass density, and Poisson's ratio-also were assessed. The Poisson's ratio was estimated with good precision at 0.499 for all samples, and the Young's moduli varied in a range of 20 kPa for one freeze-thaw cycle to 600 kPa for 10 cycles. Nevertheless, above six freeze-thaw cycles, the results were less reliable because of sample geometry artifacts. However, for the samples that underwent less than seven freeze-thaw cycles, the Young's moduli estimated with the four elastography methods showed good matching with the mechanical tensile tests with a regression coefficient varying from 0.97 to 1.07, and correlations R2 varying from 0.93 to 0.99, depending on the method.     

Hole-vibronic coupling in oligothiophenes: impact of backbone torsional flexibility on relaxation energies

Density functional theory calculations together with highly resolved gas-phase ultraviolet photoelectron spectroscopy have been applied to oligothiophene chains with up to eight thiophene rings. One of the important parameters governing the charge transport properties in the condensed phase is the amount of energy relaxation upon ionization. Here, we investigate the impact on this parameter of the backbone flexibility present in oligothiophenes as a result of inter-ring torsional motions. With respect to oligoacenes that are characterized by a coplanar and rigid backbone, the torsional flexibility in oligothiophenes adds to the relaxation energy and leads to the broadening of the first ionization peak, making its analysis more complex.     

Near optimal interval observers bundle for uncertain bioreactors

In this paper we design an interval observer for the estimation of unmeasured variables of uncertain bioreactors. The observer is based on a bounded error observer, as proposed in [Lemesle, V., & Gouzé, J.-L. (2005). Hybrid bounded error observers for uncertain bioreactor models. Bioprocess and Biosystems Engineering, 27, 311-318], that makes use of a loose approximation of the bacterial kinetics. We first show how to generate guaranteed upper and lower bounds on the state, provided that known intervals for the initial condition and the uncertainties are available. These so-called framers depend on a tuning gain. They can be run in parallel and the envelope provides the best estimate. An optimality criterion is introduced leading to the definition of an optimal observer. We show that this criterion provides directly a gain set containing the best framers. The method is applied to the estimation of the total biomass of an industrial wastewater treatment plant, demonstrating its efficiency.     

Distributed Coordination and Workflow on the World Wide Web

This paper describes WebFlow, an environment thatsupports distributed coordination services on theWorld Wide Web. WebFlow leverages the HTTP Webtransport protocol and consists of a number of toolsfor the development of applications that require thecoordination of multiple, distributed servers.Typical applications of WebFlow include distributeddocument workspaces, inter/intra-enterprise workflow,and electronic commerce. In this paper we describe thegeneral WebFlow architecture for distributedcoordination, and then focus on the environment fordistributed workflow.     

Binding of the tautomeric forms of isoniazid-NAD adducts to the active site of the Mycobacterium tuberculosis enoyl-ACP reductase (InhA): a theoretical approach

The front-line antituberculosis drug isoniazid (INH) inhibits InhA, the NADH-dependent fatty acid biosynthesis enoyl ACP-reductase from Mycobacterium tuberculosis, via formation of covalent adducts with NAD (INH-NAD adducts). While ring tautomers were found the main species formed in solution, only the 4S chain INH-NAD tautomer was evidenced in the crystallized InhA:INH-NAD complex. In this study we attempted to explore the modes of interaction and energy binding of the different isomers placed in the active site of InhA with the help of various molecular modelling techniques. Ligand and enzyme models were generated with the help of the Vega ZZ program package. Resulting ligands were then docked into the InhA active site individually using computational automated docking package AUTODOCK 3.0.5. The more relevant docked conformations were then used to compute the interaction energy between the ligands and the InhA cavity. The AM1 Hamiltonian and the QM/MM ONIOM methodologies were used and the results compared. The various tautomers were found docked in almost the same place where INH-NAD was present as predicted by earlier X-ray crystallographic studies. However, some changes of ligand conformation and of the interactions ligand-protein were evidenced. The lower binding energy was observed for the 4S chain adduct that probably represents the effective active form of the INH-NAD adducts, as compared to the 4R epimer. The two 4S,7R and 4R,7S ring tautomers show intermediate and similar binding energies contrasting with their different experimental inhibitory potency on InhA. As a possible explanation based on calculated conformations, we formulated the hypothesis of an initial binding of the two ring tautomers to InhA followed by opening of only the ring hemiamidal 4S,7R tautomer (possibly catalyzed by Tyr158 phenolate basic group) to give the 4S chain INH-NAD tight-binding inhibitor. The predictions of ligand-protein interactions at the molecular level can be of primary importance in elucidating the mechanisms of action of isoniazid and InhA-related resistances, in identifying the effective mycobactericidal entities and, in further step, in the design of a new generation of antitubercular drugs.     

Design and Implementation of an Agent Home Scheme Strategy for Prefetch-Based DSM Systems

In recent years, cluster computing has been widely investigated and there is no doubt that it can provide a cost-effective computing infrastructure by aggregating computational power, communication, and storage resources. Moreover, it is also considered to be a very attractive platform for low-cost supercomputing. Distributed shared memory (DSM) systems utilize the physical memory of each computing node interconnected in a private network to form a global virtual shared memory. Since this global shared memory is distributed among the computing nodes, accessing the data located in remote computing nodes is an absolute necessity. However, this action will result in significant remote memory access latencies which are major sources of overhead in DSM systems. For these reasons, in order to increase overall system performance and decrease this overhead, a number of strategies have been devised. Prefetching is one such approach which can reduce latencies, although it always increases the workload in the home nodes. In this paper, we propose a scheme named Agent Home Scheme. Its most noticeable feature, when compared to other schemes, is that the agent home distributes the workloads of each computing nodes when sending data. By doing this, we can reduce not only the workload of the home nodes by balancing the workload for each node, but also the waiting time. Experimental results show that the proposed method can obtain about 20% higher performance than the original JIAJIA, about 18% more than History Prefetching Strategy (HPS), and about 10% higher than Effective Prefetch Strategy (EPS).     

Estimation of heat fluxes during high-speed drilling

Heat fluxes on each cutting edge of a carbide double cutting drill are estimated during a high-speed machining process from temperature measurements in the drill tool and a direct model that has been established using the non integer system identification approach. A single experiment is required in order to characterize the transient thermal behavior of the tool. The non integer system identification method is based on the recursive linear least square algorithm. The inverse method is based on the constant function specification approach. Results obtained during machining lead to predict the tool wear and possible tool positioning defect.