Effect of ultrasound radiation on the size and size distribution of synthesized copper particles

The effect of ultrasound radiation on the size and size distribution of synthesized copper particles was investigated under various concentrations of ethylene glycol (E.G.) as a capping agent. Monodispersed copper particles were produced by the reduction of an aqueous copper (II) sulfate solution at the presence of hydrazine monohydrate. X-ray diffraction and scanning electron microscopy analysis revealed that the morphology, size, and size distribution of produced particles were influenced by the reducing agent injection rate, capping agent concentration, and sonication. Increasing the injection rate of reducing agent to an amount higher than a critical value decreases the size of copper particles and also converts the monodispersed particles to polydispersed particles. Results of using a sonifier at the reduction stage revealed that finer monodispersed copper particles can be achieved at higher injection rates related to the critical value. Increasing the concentration of E.G. as a capping agent decreases the size of copper particles, while applying ultrasound radiation along with increasing the concentration of E.G. increases the size of copper particles. Morphology of particles varies by the concentration and type of the capping agent. Higher reducing agent injection rates and the application of a sonifier at the instance of reduction result in smaller spherical particles at various capping agent concentrations.     

A new empirical model for quiescent annealing of binary co-continuous polymer blends

The high sensitivity of the morphology and final properties of co-continuous polymer blends to thermal annealing has motivated many researchers to study the evolution of their morphology during thermal annealing process. In this work, phase coarsening of a low interfacial tension polylactic acid/polycaprolactone blend and a medium interfacial tension polylactic acid/polyethylene blend during quiescent annealing was studied in detail. To this aim, characteristic length scale of the microstructure of the polymer blends was determined at different annealing times. It was found that the phase size in both blends increased linearly by time at the early stage of the annealing and then the phase coarsening rate gradually decreased at longer times. Finally, the phase size of the blends approached a finite size. The mechanisms involved in the observed phase coarsening behavior were discussed in detail. Linear and exponential phase coarsening models in the literature could not explain the observed phase coarsening behavior in the studied blends. A new empirical model was presented which showed a very good agreement with both the obtained results in this work and the previous experimental data in the literature. The obtained results indicate the significant potential of the new model in analyzing phase coarsening behavior of co-continuous polymer blends.

     

The creation of a novel fluorescent protein by guided consensus engineering

Consensus engineering has been used to increase the stability of a number of different proteins, either by creating consensus proteins from scratch or by modifying existing proteins so that their sequences more closely match a consensus sequence. In this paper we describe the first application of consensus engineering to the ab initio creation of a novel fluorescent protein. This was based on the alignment of 31 fluorescent proteins with >62% homology to monomeric Azami green (mAG) protein, and used the sequence of mAG to guide amino acid selection at positions of ambiguity. This consensus green protein is extremely well expressed, monomeric and fluorescent with red shifted absorption and emission characteristics compared to mAG. Although slightly less stable than mAG, it is better expressed and brighter under the excitation conditions typically used in single molecule fluorescence spectroscopy or confocal microscopy. This study illustrates the power of consensus engineering to create stable proteins using the subtle information embedded in the alignment of similar proteins and shows that the benefits of this approach may extend beyond stability.     

Analysis of Partial Volume Effects on Accurate Measurement of the Hippocampus Volume

Hippocampal volume loss is an important biomarker in distinguishing subjects with Alzheimer’s disease(AD)and its measurement in magnetic resonance images(MRI)is influenced by partial volume effects(PVE).This paper describes a post-processing approach to quantify PVE for correction of the hippocampal volume by using a spatial fuzzy C-means(SFCM)method.The algorithm is evaluated on a dataset of 20 T1-weighted MRI scans sampled at two different resolutions.The corrected volumes for left and right hippocampus(HC)which are 23%and 18%for the low resolution and 6%and 5%for the high resolution datasets,respectively are lower than hippocampal volume results from manual segmentation.Results show the importance of applying this technique in AD detection with low resolution datasets.     

Using Coal Fly Ash and Wastewater for Microwave Synthesis of LTA Zeolite

The reuse of industrial wastes from a coal‐fired power plant and a plasma electrolytic oxidation process was attempted to realize a zero discharge. The batch composition was adjusted by adding sodium hydroxide and sodium aluminate. A single‐mode microwave oven equipped with reflux condenser was used for crystallization under atmospheric pressure. The synthesized samples were characterized by X‐ray diffraction, scanning electron microscopy, BET, thermogravimetric analysis, and cation‐exchange capacity (CEC) measurement. Analytical results indicated that Na‐A zeolite with a defined maximum crystallinity could be successfully synthesized by hydrothermal treatment of fly ash with wastewater. Due to the high CEC, the product can be applied for gas purification and soil remediation processes.     

Beam shaping design for coupling high power diode laser stack to fiber

A beam shaping technique that rearranges the beam for improving the beam symmetry and power density of a ten-bar high power diode laser stack is simulated considering a stripe mirror plate and a V-Stack mirror in the beam shaping system. In this technique, the beam of a high power diode laser stack is effectively coupled into a standard 550 μm core diameter and a NA=0.22 fiber. By this technique, compactness, higher efficiency, and lower cost production of the diode are possible.     

Relationship between J-integral and averaged strain-energy density for U-notches in the case of large control volume under Mode I loading

The main purpose of this technical note is to present a relationship between J-integral and averaged strain-energy density () in U-notches under Mode I loading for brittle or quasi-brittle materials. In this work, control volume includes the rectilinear edge of the notch in addition to semi-circular arc of the notch root. A dimensionless function (f) between J and has been presented in this paper. Finite element analysis has been used for verification. It is found that this relationship is identical for tension or bending loading.