In vitro and in vivo degradability,biocompatibility and antimicrobial characteristics of Cu added iron-manganese alloy

In recent years,iron(Fe)based degradable metal is explored as an alternative to permanent fracture fixation devices.In the present work,copper(Cu)is added in Fe-Mn system to enhance the degradation rate and antimicrobial properties.Fe-Mn-xCu(x=0.9,5 and 10 wt.％)alloys are prepared by the melting-casting-forging route.XRD analysis confirms austenite phase stabilization due to the presence of Mn and Cu.As predicted by Thermo-Calc calculations,Cu rich phase precipitations are noticed along the austen-ite grain boundaries.Degradation behaviours of Cu added Fe-Mn alloys are investigated through static immersion and electrochemical polarization where enhanced degradation is found for higher Cu added alloys.When challenged against E.Coli bacteria,the Fe-Mn-Cu alloy media extract shows a significant bac-tericidal effect compare to the base alloy.In vitro cytocompatibility studies,as determined using MG63 and MC3T3-E1 cell lines,indicate increased cell density as a function of time for all the alloys.When implanted in rabbit femur,the newly developed alloy does not show any kind of tissue necrosis around the implants.Better osteogenesis and higher new bone formation are observed with Fe-Mn-10Cu alloy as evident from micro-computed tomography(μ-CT)and fluorochrome labelling.     

A numerical model to predict the powder–binder separation during micro-powder injection molding

The micro-powder injection molding (micro-PIM) process has the potential to bridge the gap between the design and manufacturing of micro-components that are often used in small and handy devices. Numerical modeling helps to analyze and overcome various difficulties of micro-PIM. In the present work, a numerical model is developed to predict the powder–binder separation (a common defect in PIM and especially severe in micro-PIM) during the injection of an alumina feedstock. A powder–binder separation criterion is proposed dealing with applied injection pressure and friction force between the powder and binder. An indirect comparison of feedstock travel time between two locations is used to validate the model. The predicted segregation from the simulated result is supported by a qualitative experimental measurement. The developed model can be used to optimize injection parameters to get a defect-free product.     

Design of a Variable Depth Axially Corrugated Horn Antenna at X-Band for Low Cross-Polarization Applications

Wireless Personal Communications - This paper presents a study of a class of iris localization algorithms in the presence of blurring. The effect of blurring is a serious problem in most image...     

Large Area Self-Assembled Ultrathin Polyimine Nanofilms Formed at the Liquid–Liquid Interface Used for Molecular Separation

Separation membranes with higher molecular weight cut-offs are needed to separate ions and small molecules from a mixed feed. The molecular sieving phenomenon can be utilized to separate smaller species with well-defined dimensions from a mixture. Here, the formation of freestanding polyimine nanofilms with thicknesses down to ≈14 nm synthesized via self-assembly of pre-synthesized imine oligomers is reported. Nanofilms are fabricated at the water–xylene interface followed by reversible condensation of polymerization according to the Pieranski theory. Polyimine nanofilm composite membranes are made via transferring the freestanding nanofilm onto ultrafiltration supports. High water permeance of 49.5 L m^-2 h⁻¹ bar⁻¹ is achieved with a complete rejection of brilliant blue-R (BBR; molecular weight = 825 g mol⁻¹) and no more than 10% rejection of monovalent and divalent salts. However, for a mixed feed of BBR dye and monovalent salt, the salt rejection is increased to ≈18%. Membranes are also capable of separating small dyes (e.g., methyl orange; MO; molecular weight = 327 g mol⁻¹) from a mixed feed of BBR and MO. Considering a thickness of ≈14 nm and its separation efficiency, the present membrane has significance in separation processes.     

Guayule natural rubber composites: impact of fillers on their cure characteristics,dynamic and mechanical behavior

Guayule natural rubber (GNR) is an alternative resource of Hevea natural rubber (HNR) with 99.9% cis content in its 1,4-polyisoprene chemical backbone. In this study, compounds were formulated independently with four different reinforcing fillers such as carbon black (HAF), precipitated silica (VN3), fume silica (FUM) and nanofly ash (NFA) for the advancement of GNR based products. The cure characteristic, dynamic-mechanical performance and mechanical properties of GNR composite were studied with the reinforcing effect of different fillers on GNR. The cure characteristic results demonstrated that HAF and FUM silica filled compounds had more processing safety than VN3 and NFA filled compounds. Viscoelastic parameters of the vulcanizates were studied by dynamic mechanical analysis to estimate the glass transition characteristics and dynamic behavior. The higher storage modulus of FUM silica vulcanizate was an indication of superior filler reinforcing nature and improved rolling resistance than other filled systems. Additionally, HRTEM analysis also proved the better filler dispersion ability of FUM silica in GNR matrix. The mechanical properties were studied with a variation of each filler loading of 8, 16, and 32 phr in GNR vulcanizates. The tensile strength of each filled system increased with an increase of filler content from 8 to 32 phr. In comparison, FUM silica GNR vulcanizates exhibited better mechanical properties, therefore, it was considered as a better structure-performance composite than those of HAF, VN3 and NFA filled composites.

     

Multicomponent bulk metal nitride (Nb1/3Ta1/3Ti1/3)N1−δ synthesis via reaction flash sintering and characterizations

In this research, near fully dense single phase bulk multicomponent transition metal nitride (Nb_1/3Ta_1/3Ti_1/3)N_1−δ has been successfully synthesized from mixed commercial powders of NbN, TaN and TiN via reaction flash sintering technique. This was performed with an applied pressure of ~ 35 MPa at 25°C under a constant DC electric field (~24-32 V/cm). The flash event, which is the abrupt increase in current (up to ~ 25.2 A/mm²) and temperature, occurred without preheating. The threshold power dissipation on the sample right before the flash is ~ 0.7 W/mm³. The formation of single phase (Nb_1/3Ta_1/3Ti_1/3)N_1−δ random solid solution and its compositional uniformity were confirmed by XRD and EDS, respectively. The effects of ball milling duration and limiting current density on phase formation were studied. Simulation based on Joule heating provides an estimate of the ultimate sample temperature of ~ 1850°C. Vickers hardness of the obtained (Nb_1/3Ta_1/3Ti_1/3)N_1−δ is 17.6 ± 0.6 GPa, which is comparable to similarly flash sintered ingredient binary nitrides of TaN and NbN. TGA in air shows that the oxidation resistance of (Nb_1/3Ta_1/3Ti_1/3)N_1−δ is better than that of TaN and NbN but inferior to TiN. The study demonstrates that reaction flash sintering can be a highly efficient technique for synthesizing bulk multicomponent ceramics for both material fundamental investigations and application development.     

Renewable electricity: a hope for the future

Clean Technologies and Environmental Policy -     

All forms of energy are equal,but some forms of energy are more equal than others

Clean Technologies and Environmental Policy -