Development of Graphene Oxide Nanosheets as Potential Biomaterials in Cancer Therapeutics: An In-Vitro Study Against Breast Cancer Cell Line

Journal of Inorganic and Organometallic Polymers and Materials - Recent advances in nanotechnology and nano biomaterials have attracted considerable attention in the field of cancer therapy. The...     

Sulfonated co-poly(ether imide)s with alkyne groups: Fabrication of crosslinked membranes and studies on PEM properties including MFC performance

A new diamine monomer having alkyne side-groups (DADAF) has been successfully synthesized, and it was used to prepare a series of sulfonated co-polyimides (DFN-XX) when reacted with 1,4,5,8-naphthalenetetracarboxylic dianhydride along with different mole% of 4,4′-diaminostilbene-2,2′-disulfonic acid. The membrane was made from the copolymers by solution casting route, and one of the copolymers DFN-70 was used to prepare crosslinked membranes by adding a different amount of 1,6-hexanediazide during solution casting step. The morphological transformation from non-crosslinked S-coPI to crosslinked S-coPI was observed by employing transmission electron microscopy, atomic force microscopy, and small-angle X-ray scattering analyses. Compared to the non-crosslinked DFN-XX membranes, crosslinked DFN-70 copolymer membranes showed low water uptake and improved mechanical and peroxide radical stability. Also, crosslinked DFN-70 copolymer membranes showed significantly higher proton conductivities (0.004-0.06 S cm⁻¹) compared to those of DFN-70 (0.003-0.05 S cm⁻¹) particularly, at 80°C when the relative humidity increased from 40% to 98%. Furthermore, crosslinked DFN-70 copolymer membranes exhibited significantly enhanced performance in a microbial fuel cell (MFC) as compared to those of non-crosslinked DFN-70 membrane.     

Complexation chemistry in liquid–liquid extraction of rhenium

This review addresses the dearth of knowledge about the interaction of rhenium species with organic solvents during the liquid–liquid extraction of rhenium. To describe such interactions, the aqueous chemistry of rhenium in unlike media, the extraction mechanism and the salient role of thermodynamic properties are also discussed. Formation of a rhenium‐complexed species inorganic phase and competition between the extracted species during extraction is described by inner and outer sphere coordination. Emergence of a stabilized complex in a hydrophobic environment is greatly affected by the interaction of electrostatic and/or H‐bonding. The chemistry of liquid–liquid extraction of rhenium that can further assist future studies in this area is also relevant to other metal ion systems. © 2015 Society of Chemical Industry     

Low-dimensional models for describing mixing effects in reactive extrusion of polypropylene

Spatially averaged low-dimensional models based on Liapunov-Schmidt technique of bifurcation theory have been developed to study mixing effects in peroxide-induced reactive extrusion of polypropylene degradation. The two-dimensional convection-diffusion-reaction equations for each species and the energy balance equation have been averaged in the transverse direction to obtain low-dimensional models that describe transverse (local) mixing effects on conversion, average molecular weight and temperature distribution in a reactive extruder channel with asymmetric thermal boundaries. Our models predict that incomplete local mixing due to velocity distribution, backflow and transverse diffusion may significantly reduce the conversion (by more than 50%) in a reactive extruder, compared to a plug-flow case. Our analysis further reveals that beyond a transition value of Damköhler number (Da), the overall reaction occurs in the mixing-limited regime, where the conversion and the average molecular weight of the polymer melt are determined only by the dimensionless local mixing time (which, in turn, depends on the screw speed) and are independent of Da. Increased Graetz number (i.e. slow transverse thermal diffusion) decreases the polymer-melt temperature and reduces conversion, while increase in screw speed increases viscous heat generation resulting in higher exit temperature accompanied by reduced conversion and produces off grade high molecular weight (low melt flow index) product when the mixing effect dominates the temperature effect.     

Performance prediction of high-pressure coolant assisted turning of Ti-6Al-4V

The present study focuses on the development of predictive models of average surface roughness, chip-tool interface temperature, chip reduction coefficient, and average tool flank wear in turning of Ti-6Al-4V alloy. The cutting speed, feed rate, cutting conditions (dry and high-pressure coolant), and turning forces (cutting force and feed force) were the input variables in modeling the first three quality parameters, while in modeling tool wear, the machining time was the only variable. Notably, the machining environment influences the machining performance; yet, very few models exist wherein this variable was considered as input. Herein, soft computing-based modeling techniques such as artificial neural network (ANN) and support vector machines (SVM) were explored for roughness, temperature, and chip coefficient. The prediction capability of the formulated models was compared based on the lowest mean absolute percentage error. For surface roughness and cutting temperature, the ANN and, for chip reduction coefficient, the SVM revealed the lowest error, hence recommended. In addition, empirical models were constructed by using the experimental data of tool wear. The adequacy and good fit of tool wear models were justified by a coefficient of determination value greater than 0.99.     

Effect of surfactant on the co-electrodeposition of the nano-sized ceria particle in the nickel matrix

The nickel–ceria (Ni–CeO₂) nanocomposite coatings have been pulse electrodeposited from a Watts-type electrolyte containing nano-sized CeO₂ particles produced by high-energy ball milling technique (HEBM). Sodium Lauryl Sulphate (SLS) has been added in the electrolyte as a cationic surfactant. The effects of the surfactant on the zeta potential, co-deposition and distribution of ceria particles in the nickel matrix and hardness of composite coatings have been investigated. Experimental results show that the addition of SLS up to 0.10 g/l increases the amount of co-deposited ceria particles in the nickel matrix and microhardness of the nanocomposite. However, when the amount of SLS in the electrolyte is more than 0.1 g/l, there is a tendency to form agglomerates of ceria particles in the nickel matrix resulting no further increase in hardness of the Ni–CeO₂ nanocomposite coatings.     

Effect of oil unsaturation and wax composition on stability,properties and food applicability of oleogels

Oleogelation is emerging as one of the most exigent oil structuring technique. The main objective of this study was to formulate and characterize rice bran/sunflower wax-based oleogels using eight refined food grade oils such as sunflower oil, mustard oil, soybean oil, sesame oil, groundnut oil, rice bran oil, palm oil, and coconut oil. Stability and properties of these oleogels with respect to oil unsaturation and wax composition were explored. Sunflower wax exhibited excellent gelation ability even at 1%–1.5% (w/v) concentration compared to rice bran wax (8%–10% w/v). As the oleogelator concentration increased, peak melting temperature also increased with increase in strength of oleogels as per rheological studies. X-ray diffraction and morphological studies revealed that oleogel microstructure has major influence of wax composition only. Sunflower wax oleogels unveiled rapid crystal formation with maximum oil binding capacity of 99.46% in highly unsaturated sunflower oil with maximum polyunsaturated fatty acid content. Further, the applicability of this wax based oleogels as solid fat substitute in marketed butter products was also scrutinized. The lowest value of solid fat content (SFC) in oleogel was 0.20% at 25°C, resembling closely with the marketed butter products. With increase in oil unsaturation, oleogels displayed remarkable reduction in SFC. Depending upon prerequisite, oleogel properties can be modulated by tuning wax type and oil unsaturation. In conclusion, this wax-based oleogel can be used as solid fat substitute in food products with extensive applications in other fields too.     

Effect of structural, thermal and flow parameters on steam reforming of methane in a catalytic microreactor

Steam reforming of methane in microchannels, embedded in a monolith is numerically modelled. Horizontal heating layers at equal intervals within the monolith are maintained at constant temperature. The channels are coated internally with catalyst to enhance gas–solid heterogeneous reaction. The numerical method combines the analytical solution for heat transfer through a fin, extended to a stack of fins, and the reactive flow of gases through an iterative procedure. The method offers a tool for quick design of a micro-structure, without considering detailed CFD-based model. In addition, the method can be suitably modified to address thermal management in electronic chip.The temperature within a stack between two heating layers drops near the centre of the stack, in case of an endothermic reaction. This drop, signifying the deviation from isothermal behaviour is found more near the heating layer, and tapers off near the centre of the stack. When the feed temperature is significantly less than the temperature of the heating layer, the portion of the reactor, away from the heating layer remains at a substantially lower temperature, particularly when the number of channels between two heating layers is large. Accordingly, the conversions in the individual channels at the outlet are affected. If the channel wall becomes thicker, the drop in fluid temperature away from the heating layer is more. The increase in feed velocity leads to larger drop in temperature and overall conversion. The decrease in thermal conductivity and the increase in number of channels between two heating layers enhance the temperature drop. None of these functionalities appears to be linear.     

Embedded macroporous elastomers by hydrostatic fracturing for flexible strain‐sensor applications

A method is proposed for fabricating flexible materials embedded with macroporous regions by inducing fractures under point loading. Possible use of these structures in strain sensing is demonstrated. Injecting air at high pressure through a needle‐tip generates 3‐dimensional fractures in homogeneously crosslinked polydimethylsiloxane (PDMS) media, whereas a 2‐dimensional planar fracture is generated in a sandwich‐like structure wherein a softer layer is bounded by two stiffer layers. Size‐dependence of 3‐dimensional fractures on stiffness of the media which is controlled by the crosslinker concentration shows a maximum, suggesting an optimal stiffness for generating largest fracture. The size of the 2‐dimensional fractures (～5 cm) generated inside the sandwiched layer is huge as compared to the 3‐dimensional fractures (～1 mm) under the similar conditions. Two dimensional fractured surfaces show ridges with feature length monotonically becoming smaller with stiffness. Embedded rough planar domains are created by introducing 2‐dimensional fractures at distances close enough to overlap. Using this method an embedded 2‐dimensional porous domain of polyaniline nanostructures is realized in flexible PDMS matrix. An Ohmic nature of these embedded polyaniline domains with an ability to change resistance under compression establishes their suitability for developing inexpensive and flexible strain sensors. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43681.