Electrodeposition and characterization of nano-crystalline antimony telluride thin films

Electrodeposition is a promising low-cost method to fabricate nanostructured thermoelectric thin films such as Sb₂Te₃. However, electrodeposition of crystalline Sb₂Te₃ without the need for additional processing and with good compositional control has presented a challenge. Here we report on the electrodeposition of crystalline Sb₂Te₃ thin films at room temperature from a tartaric-nitric acid electrolyte using a pulsed, potentiostatic process. The effects of synthesis conditions on the resulting microstructure and compositional homogeneity are investigated using x-ray diffraction, electron diffraction, electron microscopy, and energy dispersive x-ray spectroscopy. The composition of the Sb-Te films was found to be dependent on the interval between pulses, a result that is likely due to the slow kinetics associated with Sb₂Te₃ formation at the surface. We also observed a change in texture and microstructure with varied applied pulse duration: for short pulse durations a lamellar microstructure with a {000?} texture forms, whereas for longer pulse durations a more equiaxed and randomly oriented microstructure forms. The thermal conductivities of the pulsed electrodeposited films are surprisingly low at less than 2 W/K·m and are found to systematically decrease with reduced pulse time.     

Some considerations regarding finishing by abrasive flap wheels

The diminishing of the surface roughness of a metallic part can be performed by using various finishing methods, polishing by means of abrasive flap wheels being one of them. There are several factors that influence the roughness of surfaces finished by means of abrasive flap wheels. When polishing external cylindrical surfaces by means of abrasive flap wheels, the surface roughness can be changed more easily if the following elements are modified: the peripheral speed of the workpiece and of the abrasive flap wheel, the speed of the longitudinal feed, and the grit size of the abrasive material. Experimental research has allowed for the establishment of power-type functions which highlight the influence exerted by the above-mentioned factors on the size of the surface roughness parameters R _a , RS, RSm, Rku. Analyses of the experimental results have shown that, in the case of the R _a roughness parameter, from among the range of interactions of orders 2 and 3, only the interaction between the rotation speed of the abrasive flap wheel and the speed of the longitudinal feed seems to be significant.     

Recent Advances on the Roles of PCSK-9 Inhibitors in the Management of Acute Ischemic Stroke Patients

Acute ischemic stroke (AIS) represents an important cause of disability and death. Since only a minor percentage of patients with AIS are eligible for acute therapy, the management of risk factors is mandatory. An important risk factor of AIS is hyperlipemia. The current guidelines recommend a strict correction of it. Statins are recommended as the first-line treatment, while proprotein convertase subtilin/kexin type 9 (PCSK-9) inhibitors are administered as a second or even third option when the goal for a low-density lipoprotein cholesterol (LDL-C) level is not achieved. PCSK-9 inhibitors effectively decrease the LDL-C levels through the inhibition of PCSK-9-LDL-receptor complex formation. The in-depth understanding of the PCSK-9 protein mechanism in the metabolism of LDL-C led to the development of effective targeted approaches. Furthermore, a better understanding of the LDL-C metabolic pathway led to the development of newer approaches, which increased the therapeutic options. This article aims to offer an overview of the PCSK-9 inhibitors and their mechanism in reducing the LDL-C levels. Moreover, we will present the main indications of the current guidelines for patients with hyperlipemia and for those who have suffered an acute ischemic stroke, as well as the importance of LDL-C reduction in decreasing the rate of a recurrence.     

Assessing the reactivity of TiCl3 and TiF3 with hydrogen

TiCl₃ and TiF₃ additives are known to facilitate hydrogenation and dehydrogenation in a variety of hydrogen storage materials, yet the associated mechanism remains under debate. Here, experimental and computational studies are reported for the reactivity with hydrogen gas of bulk and ball-milled TiCl₃ and TiF₃ at the temperatures and pressures for which these additives are observed to accelerate reactions when added to hydrogen storage materials. TiCl₃, in either the α or δ polymorphic forms and of varying crystallite size ranging from ～5 to 95 nm, shows no detectable reaction with prolonged exposure to hydrogen gas at elevated pressures (～120 bar) and temperatures (up to 200 °C). Similarly, TiF₃ with varying crystallite size from ～4 to 25 nm exhibits no detectable reaction with hydrogen gas. Post-exposure vibrational and electronic structure investigations using Fourier transform infrared spectroscopy and x-ray absorption spectroscopy confirm this analysis. Moreover, there is no significant promotion of H₂ dissociation at either interior or exterior surfaces, as demonstrated by H₂/D₂ exchange studies on pure TiF₃. The computed energy landscape confirms that dissociative adsorption of H₂ on TiF₃ surfaces is thermodynamically inhibited. However, Ti-based additives could potentially promote H₂ dissociation at interfaces where structural and compositional varieties are expected, or else by way of subsequent chemical transformations. At interfaces, metallic states could be formed intrinsically or extrinsically, possibly enabling hydrogen-coupled electronic transfer by donating electrons.     

Thin Film Growth of nbo MOFs and their Integration with Electroacoustic Devices

Metal‐organic frameworks (MOFs) with the “nbo” topology constitute a diverse suite of more than 100 nanoporous materials, but their use in applications such as chemical sensing and membranes is inhibited by a lack of methods for growing them as thin films. Here, layer‐by‐layer (LBL) and solvothermal growth of “nbo” films is demonstrated and it is established for the first time that interlinker steric hindrance is a critical factor in determining the effectiveness of the LBL method. Film growth is demonstrated for three “nbo” MOFs: NOTT‐100 and NOTT‐101, which have the R‐3m space group and are deposited by the LBL method, and PCN‐14, with the R‐3c space group, which is deposited by a solvothermal approach. Continuous and dense films of NOTT‐100 and NOTT‐101 are obtained and LBL growth is verified by observing deposition with a quartz crystal microbalance technique, which also yields the temperature dependence. Oxygen plasma treatment is found to be a useful tool for promoting the MOF film growth under solvothermal conditions. Effective mechanical coupling of these films to the substrate is demonstrated by growing them on surface acoustic wave sensors, which respond reversibly to vapors of water, acetone, and n‐hexane.     

Quantum correlations in cavity QED networks

We present a review of the dynamical features such as generation, propagation, distribution, sudden transition and freezing of the various quantum correlation measures, as Concurrence, Entanglement of Formation, Quantum Discord, as well their geometrical measure counterparts within the models of Cavity Quantum Electrodynamics Networks. Dissipation and thermal effects are discussed both in the generation of quantum correlations as well as their effect on the sudden changes and freezing of the classical and quantum correlations in a cavity quantum electrodynamical network. For certain initial conditions, double transitions in the Bures geometrical discord are found. One of these transitions tends to disappear at a critical temperature.