Plasma-Enhanced Chemical Vapor Deposition of Boron Nitride Using Polymeric Cyanoborane as Source

The plasma-enhanced chemical vapor deposition (PECVD) of boron nitride films was studied using polymeric cyanoborane, (CNBH₂) n , a material previously examined by thermally activated CVD. The PECVD procedure yields boron nitride coatings containing ≅20 wt% paracyanogen as a contaminant. This impurity can be removed by heat treatment under vacuum or in an ammonia atmosphere. The boron nitride coatings are hexagonal and appear to be boron deficient. The PECVD process takes place at 300°C, measured at the backside of the substrate, as compared with 600°C in the thermally activated CVD process.     

Dielectric characteristics of sisal–oil palm hybrid biofibre reinforced natural rubber biocomposites

Natural rubber was reinforced with sisal and oil palm fibers. Biocomposites were prepared by varying the weight fraction of the fibers. The dielectric properties such as dielectric constant, volume resisitivity and dielectric loss factor of the biocomposites were evaluated as a function of fiber loading, frequency and chemical modification of fibers. The dielectric constant values were found to be higher for fiber reinforced system than the gum due to polarization exerted by the incorporation of lignocellulosic fibers. Chemical modification of fibers resulted in decrease of dielectric constant values and volume resisitivity values. The volume resisitivity of the composites was found to decrease with fiber loading due to increase of hydrophilicity imparted by the lignocellulosic fibers. The dissipation factor was found to increase with fiber content.     

Confidential and efficient asset proof for bitcoin exchanges

Technological advancements boost the business to play a crucial role in a country’s economic success. Cryptography-based currencies, called as cryptocurrencies, are now leading the world’s economy. With the increasing popularity of cryptocurrencies, cryptocurrency exchanges have emerged to support cryptocurrency-related services. Among cryptocurrencies, bitcoin takes the lead and it is widely accepted by the world community. Lots of security issues are arising day by day and the exchange should handle all of of them sensibly. It is necessary that the exchange should be solvent all the time in terms of its assets and liabilities for its survival. For this, periodic settlement of the accounts should be done using appropriate techniques. The information exchange needed for this should be concealed from the adversaries. Cryptography-based techniques with zero-knowledge protocols are suitable for this purpose. Maxwell’s proof of liabilities is the first cryptography-based method to verify the user assets. It makes use of binary Merkle hash trees for representing the proof of liabilities. The root node reveals the total assets of the exchange, which will attract the adversaries to execute an attack. Later the Dagher et al scheme, a privacy preserving proof of asset for bitcoin exchanges, was proposed. The scheme works in an interactive manner that requires the collaboration of the exchange and the user. This paper proposes an efficient non-interactive proof of assets for bitcoin exchanges.     

Shedding light on electrodeposition dynamics tracked <Emphasis Type="Italic">in situ</Emphasis> via soft X-ray coherent diffraction imaging

The in situ physicochemical analysis of nanostructured functional materials is crucial for advances in their design and production. X-ray coherent diffraction imaging (CDI) methods have recently demonstrated impressive potential for characterizing such materials with a high spatial resolution and elemental sensitivity; however, moving from the current ex situ static regime to the in situ dynamic one remains a challenge. By combining soft X-ray ptychography and single-shot keyhole CDI, we performed the first in situ spatiotemporal study on an electrodeposition process in a sealed wet environment, employed for the fabrication of oxygen-reduction catalysts, which are key components for alkaline fuel cells and metal-air batteries. The results provide the first experimental demonstration of theoretically predicted Turing–Hopf electrochemical pattern formation resulting from morphochemical coupling, adding a new dimension for the in-depth in situ characterization of electrodeposition processes in space and time.

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Epitaxial TiOx Surface in Ferroelectric BaTiO3: Native Structure and Dynamic Patterning at the Atomic Scale

Surfaces and interfaces of ferroelectric oxides exhibit enhanced functionality, and therefore serve as a platform for novel nano and quantum technologies. Experimental and theoretical challenges associated with examining the subtle electro‐chemo‐mechanical balance at metal‐oxide surfaces have hindered the understanding and control of their structure and behavior. Here, combined are advanced electron‐microscopy and first‐principles thermodynamics methods to reveal the atomic‐scale chemical and crystallographic structure of the surface of the seminal ferroelectric BaTiO₃. It is shown that the surface is composed of a native <2 nm thick TiO_x rock‐salt layer in epitaxial registry with the BaTiO₃. Using electron‐beam irradiation, artificial TiO_x sites with sub‐nanometer resolution are successfully patterned, by inducing Ba escape. Therefore, this work offers electro‐chemo‐mechanical insights into ferroelectric surface behavior in addition to a method for scalable high‐resolution beam‐induced chemical lithography for selectively driving surface phase transitions, and thereby functionalizing metal‐oxide surfaces.     

Development of a Novel Catalytic Membrane Reactor for Heterogeneous Catalysis in Supercritical CO2

A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO₂). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO₂ for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 °C in 10 MPa (H₂: 1 MPa, CO₂: 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min.