Tuning of shear thickening behavior and elastic strength of polyvinylidene fluoride via doping of ZnO-graphene

ZnO rice like nonarchitects are grafted on the graphene carbon core via a rapid microwave synthesis route. The prepared grafted systems are characterized via XRD, SEM, RAMAN, and XPS to examined the structural and morphological parameters. Zinc oxide grafted graphene sheets (ZnO-G) are further doped in β-phase of polyvinylidene fluoride (PVDF) to prepare the polymer nanocomposites (PNCs) via mixed solvent approach (THF/DMF). β-phase confirmation of PVDF PNCs is done by FTIR studies. It is observed that ZnO-G filler enhances the β-phase content in the PNCs. Non-doped PVDF and PNCs are further studied for rheological behavior under the shear rate of 1–100 s⁻¹. Doping of ZnO-G dopant to the PVDF matrix changes its discontinuous shear thickening (DST) behavior to continues shear thickening behavior (CST). Hydrocluster formation and their interaction with the dopant could be the reason for this striking DST to CST behavioral change. Strain amplitude sweep (10⁻³% -10%) oscillatory test reveals that the PNCs shows extended linear viscoelastic region with high elastic modulus and lower viscous modulus. Effective shear thickening behavior and strong elastic strength of these PNCs present their candidature for various fields including mechanical and soft body armor applications.     

Serial cytological assay of micronucleus induction: a new tool to predict human cancer radiosensitivity

The role of the propeptide sequence and a disulfide bridge between sites 1 and 122 in chymotrypsin has been examined by comparing enzyme activities of wild-type and mutant enzymes. The kinetic constants of mutants devoid of the Cys1-Cys122 disulfide-linked propeptide show that this linkage is not important either for activity or substrate specificity. However this linkage appears to be the major factor in keeping the zymogen stable against non-specific activation. A comparison of zymogen stabilities showed that the trypsinogen propeptide is ten times more effective than the chymotrypsinogen propeptide in preventing non-specific zymogen activation during heterologous expression and secretion from yeast. This feature can also be transferred in trans to chymotrypsinogen; i.e. the chymotrypsin trypsin propeptide chimera forms a stable zymogen.     

Multi purpose research reactor

At present Dhruva and Cirus reactors provide the majority of research reactor based facilities to cater to the various needs of a vast pool of researchers in the field of material sciences, physics, chemistry, bio sciences, research & development work for nuclear power plants and production of radio isotopes. With a view to further consolidate and expand the scope of research and development in nuclear and allied sciences, a new 20 MWt multi purpose research reactor is being designed. This paper describes some of the design features and safety aspects of this reactor.     

Eco-friendly electronics,based on nanocomposites of biopolyester reinforced with carbon nanotubes: a review

ABSTRACT

Fabrication of electronic materials from nanocomposite of biopolyesters reinforced with carbon nanotubes can be regarded as the effective alternative for conventional nanocomposites consisting of non-biodegradable polymers. Commercial availability of biopolyester-based nanocomposites is limited because of their high cost compared to other polymers, but the factor of their compostable nature is worthless for environmental protection. Such nanocomposites have potential applications in biodegradable sensors, EMI materials, etc. In this review, the current progress of biopolyester/CNTs nanocomposites in the field of biodegradable electronics is reviewed and also the impact of CNTs dispersion on electrical, thermal and mechanical properties of eco composites is stipulated.     

The chemistry of dicalcium silicate mineral

Dicalcium silicate is of vital importance in several fields of silicate science. It exists in several polymorphic forms, of which one (the-form) is stable at room temperature without any stabilizer. The-form is commonly found in ordinary portland cement (OPC) in association with stabilizing ions. Stabilization of other forms,,_L,_H and_m for structural and other studies have been reported. Theoretical structural analysis using topology has been reported to be of value in understanding the stabilization process of the polymorphs. The conversion of form is at times a problem in the cement industry, in addition to the formation of unwanted compounds, such as spurrite. The-form is low in hydraulic properties but in the presence of impurities such as excess CaO over the stoichiometric ratio, shows fairly high hydraulic properties. Of the other phases, the hydraulic properties of the a forms are quite encouraging but the choice of stabilizers etc. plays a dominant role. Correlation of hydraulicity with structural properties such as crystal defects, etc., has been reported but satisfactory explanation is yet to come. The hydration products of-C₂S are quite similar to those of C₃S but the kinetics are fairly slow. In the presence of active silica, and at elevated temperatures, even the-form hydrates at a faster rate. The influence of chemical accelerators on the hydration of C₂S at room temperature is well studied and NaF is found to be one of the best accelerators. The formation of reactive-C₂S by different preparative methods shows a quite interesting trend for potential manufacture of low-temperature inorganic cement or OPC with low C₃S; even utilization of low-grade limestone could be possible. The role of C₂S in the hydration of aluminous cements is being increasingly recognized and, in fact, a newer class of cements called alumina-belite cement, etc., are being developed in which C₂S is purposely maintained as a major phase.     

An in vivo Evaluation of Ultra-fine Grained Titanium Implants

The present work focuses mainly on an in vivo evaluation of ultra fine grained titanium(UFG-Ti) obtained by severe plastic deformation(SPD).The SPD on commercially produced Grade 2 titanium(Cp-Ti) resulted in the refinement of the grain size by several orders of magnitude.Polished surfaces having similar roughness from both UFG-Ti and Cp-Ti were prepared.In vitro test revealed the presence of fibronectin,which was involved in the attachment of the cells to the substrate.Phase contrast micrographs showed the...     

Atomic Force Microscopy as a Nanometrology Tool: Some Issues and Future Targets

Diverse novel nanomaterials are being developed for a wide range of applications nowadays. Atomic force microscopy (AFM) assumes specific importance for the measurement of size and other related properties for such nanomaterials. The different aspects related to AFM modes of operation, nanopositioning, sensing systems as well as calibration for reliable characterization in order to meet the nanometrology requirements are discussed. The future targets in this context, set by nanometrology institutes, are also highlighted.     

Optimisation and comparative study on the addition of shrimp protein hydrolysate and shrimp powder on physicochemical properties of extruded snack

The effect of an addition of shrimp protein hydrolysate and shrimp powder on the physicochemical properties of extruded snack was studied. Rice flour and cornflour were used as base materials, and extrusion was done using corotating twin‐screw extruder. A mixture response surface methodology was used to study the effect of ingredient mixture on the physical, functional and sensory properties of extrudates. Linear and quadratic mixture response regression model was fitted to the response variables, and it was evaluated using R² values. Based on the desirability function score, the optimum combination of ingredient was 47.75% rice flour, 38.64% cornflour, 5.95% hydrolysate and 7.67% shrimp protein powder. It was observed that an addition of shrimp hydrolysate more than 5% (7.5%) improved the crispiness. Sensory evaluation revealed that shrimp hydrolysate and shrimp powder can be used at 5–7.5% level for developing protein‐rich extruded products without affecting sensory characteristics.