Biohydrogen Production from Organic Waste – A Review

Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency.     

Physico-Mechanical Properties of Nano Silica-Filled Epoxy-Based Mono and Hybrid Composites for Structural Applications

Silicon - This research article describes the results of nano-silica (nSiO2) filled epoxy (Ep) mono composites with different contents (0.5, 1.0, 1.5, 3, and 5 wt.%) and carbon...     

Tailoring the morphology of hydroxyapatite particles using a simple solvothermal route

Nanometric and sub-micrometric monodispersed hydroxyapatite (HAp) particles with different morphologies (spheres and rods) were synthesized via a simple solvothermal method using Ca(NO₃)₂·4H₂O and P₂O₅ as starting materials without any requirement to use organic templates. The growth, evolution and purity of the nanoparticles were investigated by controlling the synthesis conditions, including the alkalinity and the temperature of the solvothermal treatment. The increasing of the alkaline ratio results in a great change of the elaborated particles’ morphology that evolved from anisotropic forms (nanorods, sub-micrometric rod) at pH 9, short rod particles at pH 9.5 to spherical ones at higher pH (pH≥10).Powder X-Ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Nitrogen adsorption and desorption studies (BET) were used to characterize the structure and composition of the as-prepared samples.The thermal analysis of the synthesized particles conducted by differential scanning calorimetry (DSC) shows a good stability for all morphologies with a degradation temperature reaching 1300 °C.     

Analytical Drain Current Modeling and Simulation of Triple Material Gate-All-Around Heterojunction TFETs Considering Depletion Regions

Semiconductors - This paper deals with electrostatic behavior of triple-material gate-all-around hetero-junction tunneling field-effect transistors (TMGAA-HJTFET) device. The model is advantageous...     

Electrosynthesis of poly-2,5-pyridine promoted by nickel complexes

A nickel-catalysed electrochemical method for the synthesis of poly-2,5-pyridine is suggested. It is based on the reduction of 2,5-dibromopyridine carried out by generating electrochemically and continuously recycling nickel(0) from nickel(II) in the presence of both bipyridyl and triphenyl-phosphine. The simultaneous presence of these ligands is required to avoid the abstraction of the nickel promoter from the electrocatalytic cycle, thus allowing a very satisfactory yield (89%) to be achieved. Bipyridyl is in fact a ligand suitable for binding the metal in the 2+ oxidation state, so that it is able to compete with the nitrogen-coordination sites present in the polymer originated in the process, thus maintaining nickel(II) in the solution, while triphenylphosphine is able to stabilize nickel(0), thus preventing side reactions of this very reactive species with the solvent. The conductivity of poly-2,5-pyridine after doping has also been tested. Doping with electron-acceptor species such as iodine or bromine leads to charge-transfer complexes displaying semiconducting properties, while n-doping with sodium naphthalenide causes a larger increase in the electrical conductivity, which suggests that a conducting material is obtained.     

Synthesis,characterization and low frequency AC conduction of polyaniline/niobium pentoxide composites

New types of conducting polyaniline–niobium pentoxide (PANI/Nb₂O₅) nanocomposites have been synthesized by in situ deposition technique by placing fine grade powder of Nb₂O₅ during in situ polymerization of aniline. The composites formed were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). XRD and TEM indicated the dominant role-played by Nb₂O₅ particles, whereas XPS indicated incomplete protonation of imine moieties. SEM images indicated a systematic morphological variation of particles aggregated in the composite matrix as compared to the pristine PANI. Three step decomposition patterns were observed for PANI and its composites. AC conductivity and dielectric response of the composites were investigated in the frequency range, 10²–10⁶ Hz. AC conductivity obeyed the power law index, which decreased with increasing wt.% of Nb₂O₅. PANI showed high dielectric constant, which could be related to conductivity relaxation phenomenon. Both dielectric constant and dielectric loss decreased with increasing wt.% of Nb₂O₅. Variations in measured AC response parameters with increasing Nb₂O₅ contents of the composite followed systematic trends that are similar to those observed with decreasing temperature and level of doping.     

Cross-section measurements for the (n,p) and (n,α) reactions on 23Na and for the (n,p) reaction on 26Mg at the neutron energies from 13.6 to 14.9 MeV

Cross sections were measured at neutron energies from 13.6 to 14.9 MeV for the reactions ²³Na(n,p)²³Ne and ²³Na(n,α)²⁰F, and ²⁶Mg(n,p)²⁶Na leading to short-lived products. The production of short-lived nuclei and the spectra accumulation have been carried out by cyclic activation method. Corrections were made for the effects of gamma ray attenuation, coincidence summing, pulse pile-up, dead time, neutron flux fluctuations and scattered low energy neutrons.     

Nano/micro-structuring of oxide thin film under SHI irradiation

In the present work, we have studied the nano/micro-patterning of the surface of NiO thin films on different substrates (SiO₂, Si and Al) using 100 MeV Ag ions at LN₂ temperature and at an incidence angle of 75^° with the beam axis. The surface morphology of the irradiated surface is observed by Atomic force microscopy (AFM). AFM images of ion beam irradiated samples show the restructuring of initially flat and coherent NiO film into an almost periodic NiO lamellae structure. The quite regular lamellae with width, height and average distance of hundreds of nm are oriented perpendicular to the beam direction. Section analysis of the AFM images reveal that the width of the lamellae is less in case of NiO films deposited on SiO₂ substrate in comparison to Al substrate. The cracking and the development of lamellae structure is observed at higher fluence in the case of Al substrate in comparison to other substrates.     

A model for the evolution of grain size distribution during superplastic deformation

In a recent paper, we postulated that a grain size distribution in a polycrystal can result in mixed mode deformation during superplastic flow. Since diffusional flow is strongly grain size-dependent while power-law creep is not, it was inferred that large grains may deform by power-law creep, while concomitantly, the small grains deform by diffusional creep. Here, a first order model for dynamic change in the grain size distribution with strain is developed to explain the shape of the stress-strain curves obtained during superplastic deformation of aluminum alloys. The model is based on the simple assumption that regions deforming by diffusion creep suffer strain induced grain growth, while dislocation creep results in grain refinement. In spite of the approximation, the model correctly predicts the shape of the stress-strain curves. The possible significance of these concepts in classical dynamic recrystallization phenomena is also discussed.