Electronic properties of binary and ternary, hard and refractory transition metal nitrides

We present a detailed study of the microstructure and morphology of a very wide variety of binary transition metal nitrides (TiN, ZrN and TaN) grown by pulsed laser deposition (PLD) as well as of ternary nitrides consisting of Ti alloyed with Ta or Zr. We also present a critical investigation of their electronic properties such as the plasma energy, electrical resistivity and work function, with respect to their composition, microstructure and the electronic structure of the constituent metals using optical reflectance spectroscopy, Hall effect and Kelvin probe measurement

Untapped potential of moving bed biofilm reactors with different biocarrier types for bilge water treatment: A laboratory‐scale study

Two labscale aerobic moving bed biofilm reactor (MBBR) systems, with a different type of biocarrier in each (K3 and Mutag BioChip), were operated in parallel for the treatment of real saline bilge water. During the operation, different stress conditions were applied in order to evaluate the performance of the systems: organic/hydraulic load shock (chemical oxygen demand (COD): 9 g L‐1; hydraulic retention time (HRT): 48–72 h) and salinity shock (salinity: 40 ppt). At the same time, the microbiome in the biofilm and suspended biomass was monitored through 16S rRNA gene analysis in order to describe the changes in the microbial community. The dominant classes were Alphaproteobacteria (families Rhodospirillaceae and Rhodobacteraceae) and Bacteroidia (family Lentimicrobiaceae), being recorded at high relative abundance in all MBBRs. The structure of the biofilm was examined and visualized with scanning electron microscopy (SEM) analysis. Both systems exhibited competent performance, reaching up to 86% removal of COD under high organic loading conditions (COD: 9 g L‐1). In the system in which K3 biocarriers were used, the attached and suspended biomass demonstrated a similar trend regarding the changes observed in the microbial communities. In the bioreactor filled with K3 biocarriers, higher concentration of biomass was ob-served. Biofilm developed on Mutag BioChip biocarriers presented lower biodiversity, while the few species identified in the raw wastewater were not dominant in the bioreactors. Through energy-dispersive X‐ray (EDX) analysis of the biofilm, the presence of calcium carbonate was discovered, indicating that biomineralization occurred

Stress evolution in magnetron sputtered Ti–Zr–N and Ti–Ta–N films studied by in situ wafer curvature: role of energetic particles

Stress evolution during reactive magnetron sputtering of binary TiN, ZrN and TaN thin films as well as ternary Ti–Zr–N and Ti–Ta–N solid-solutions was studied using real-time wafer curvature measurements. The energy of the incoming particles (sputtered atoms, backscattered Ar, ions) was tuned by changing either the metal target (MTi = 47.9, MZr = 91.2 and MTa = 180.9 g/mol), the plasma conditions (effect of pressure, substrate bias or magnetron configuration) for a given target or by combining different metal targets during co-sputtering. Experimental results were discussed using the average energy of the incoming species, as calculated using Monte-Carlo simulations (SRIM code). In the early stage of growth, a rapid evolution to compressive stress states is noticed for all films. A reversal towards tensile stress is observed with increasing thickness at low energetic deposition conditions, revealing the presence of stress gradients. The tensile stress is ascribed to the development of a ‘zone T’ columnar growth with intercolumnar voids and rough surface. At higher energetic deposition conditions, the atomic peening mechanism is predominant: the stress remains largely compressive and dense films with more globular microstructure and smooth surface are obtaine

Effects of biomechanical properties of blood on surface tension-driven flows in superhydrophilic channels

Surface tension-driven microfluidic flows offer low-cost solutions for blood diagnostics due to the pump-less flow handling. Knowledge of the influence of the biomechanical properties of blood on such flows is key to design such devices; however, a systematic examination of that influence is lacking in the literature. We report on the effects of specific hemorheological factors for flows in a superhydrophilic microchannel. Whole human blood and erythrocyte suspensions in phosphate buffer and dextran solutions were tested. Heat-treated counterparts of the aforementioned samples were produced to alter the deformability of the cells. The flow of the samples was imaged and characterized using micro-particle image velocimetry and tracking techniques to probe the effects of hematocrit, and erythrocyte aggregation and deformability. Meniscus velocities, velocity profiles in the channel, and local and bulk shear rates were derived. The mean velocity of blood was affected by the increasing sample viscosity and the reduced erythrocyte deformability as expected. The increased erythrocyte aggregation appeared to affect more the shape of the velocity profiles in the normal, compared to the heat-treated samples. Very high shear rates are observed in the early stages of the flow, suggesting high erythrocyte disaggregation, persisting sufficiently strong until the flow reaches the end of the channel

Controlling the optical properties of nanostructured oxide-based polymer films

International audienceA bulk scale process is implemented for the production of nanostructured film composites comprising unary or multi-component metal oxide nanoparticles dispersed in a suitable polymer matrix. The as-received nanoparticles, namely Al2O3, SiO2 and TiO2 and binary combinations, are treated following specific chemical and mechanical processes in order to be suspended at the optimal size and composition. Subsequently, a polymer extrusion technique is employed for the fabrication of each film, while the molten polymer is mixed with the treated metal oxide nanoparticles. Transmission and reflection measurements are performed in order to map the optical properties of the fabricated, nanostructured films in the UV, VIS and IR. The results substantiate the capability of the overall methodology to regulate the optical properties of the films depending on the type of nanoparticle formation which can be adjusted both in size and composition

Controlling the optical properties of nanostructured oxide-based polymer films

A bulk scale process is implemented for the production of nanostructured film composites comprising unary or multi-component metal oxide nanoparticles dispersed in a suitable polymer matrix. The as-received nanoparticles, namely Al[Formula: see text]O[Formula: see text], SiO[Formula: see text] and TiO[Formula: see text] and binary combinations, are treated following specific chemical and mechanical processes in order to be suspended at the optimal size and composition. Subsequently, a polymer extrusion technique is employed for the fabrication of each film, while the molten polymer is mixed with the treated metal oxide nanoparticles. Transmission and reflection measurements are performed in order to map the optical properties of the fabricated, nanostructured films in the UV, VIS and IR. The results substantiate the capability of the overall methodology to regulate the optical properties of the films depending on the type of nanoparticle formation which can be adjusted both in size and composition

Structure, stability and mechanical performance of AlN: ag nanocomposite films

Nanocomposite films consisting of a hard AlN matrix incorporating soft Ag inclusions (AlN:Ag) and which are suitable for protective coatings are presented. The growth has been performed using Pulsed Laser Deposition and the film structural properties, such as nanoparticle size and distribution, were studied in relation to the growth parameters, such as metal content and PLD working pressure and laser power. High resolution transmission electron microscopy and nanoindentation were employed in order to determine the film composition, inclusions' crystal structure and mechanical properties respectively. The employed Ag nanoparticles had average sizes ranging between 3–10 nm and were clearly separated by the matrix material. The critical parameters, which determine the nanoparticle size and distribution, and the decisive role of the latter on the mechanical performance of AlN:Ag nanocomposite films are establishe

Biowaste-based biochar: A new strategy for fermentative bioethanol overproduction via whole-cell immobilization

This work explores the potential use of biochar as a microbial cell carrier enhancing the efficiency of alcoholic fermentations. Olive kernels, vineyard prunings, sewage sludge and seagrass residues were applied as biowaste for biochar production through pyrolysis at two different temperatures (250 °C and 500 °C), while a commercial type of non-biomass char was also employed for benchmarking purposes. Apart from vineyard prunings pyrolyzed at 250 °C, all other carbonaceous materials presented crystalline phases including halite, calcite, sylvite and/or silicon. Moreover, increase in pyrolysis temperature enhanced biochar's porosity and BET-specific surface area, which reached 41.7 m 2 g −1 for VP-based biochar remaining at lower levels (0.15–5.3 m 2 g −1 ) in other specimens tested. Elemental analysis demonstrated reduction in oxygen and increase in the carbon content of biochars produced at elevated temperatures, while biochar from seagrass included residues of chloride (0.3–5.14%). Three major yeasts were immobilized on materials exhibiting the highest surface areas and applied in repeated batch fermentations using Valencia orange peel hydrolyzates as feedstock. The biocatalysts developed using S. cerevisiae and K. marxianus immobilized on vineyard prunings-based biochar exhibited exceptional ethanol productivities as compared to the relevant literature, which reached 7.2 g L −1 h −1 and 7.3 g L −1 h −1 respectively. Although the aforementioned strains improved biofuel production by 36–52% compared to the conventional process, P. kudriavzevii KVMP10 was not efficient following immobilization on biochar. The approach constitutes an innovative method for bioenergy production, demonstrating a novel application of biochar in industrial biotechnology which incorporates important technological advances such as enhanced biofuel production and biomass recycling