The role of interfacial interactions on the crystallinity and nanomechanical properties of clay–polymer nanocomposites: A molecular dynamics study

Polymer clay nanocomposites (PCN) show enhanced mechanical, thermal, liquid or gas barrier properties in comparison to pure polymer. However, the mechanisms for enhancement of these physical properties of PCN are not well understood. This knowledge is important for tailoring the properties of PCN to desired specifications. Our earlier study showed that organic modifiers have significant influence on the crystallinity and nanomechanical properties of PCN. For quantitative evaluation of the influence of organic modifiers on the crystallinity and nanomechanical properties of PCN, molecular models of three intercalated PCNs containing same polymer and clay but with three different organic modifiers are constructed in this work. Using molecular dynamics simulations, the interaction energies among the different constituents of PCNs are evaluated. This study reveals that the interactions between polymer, organic modifiers, and intercalated clay are critical factors in controlling the crystallinity and enhancement of nanomechanical properties of PCN. We have described the possible mechanisms leading to change in crystallinity and nanomechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Pressure induced magnetic phase transition in Fe3Pt

Results of electronic band structure calculations for Fe₃Pt performed using the linear muffin-tin orbital method in the tight binding representation are presented here. From the total energy calculations we find that at ambient conditions Fe₃Pt is stable in the ferromagnetic phase, in agreement with the experimental results. Under compression Fe₃Pt is found to undergo a magnetic transition to paramagnetic phase at a pressure of about 4 GPa, in excellent agreement with experimental observations.     

Scientific Data Collections and Distributed Collective Practice

As the basic sciences become increasingly information-intensive, the management and use of research data presents new challenges in the collective activities that constitute scholarly and scientific communication. This also presents new opportunities for understanding the role of informatics in scientific work practices, and for designing new kinds tools and resources needed to support them. These issues of data management, scientific communication and collective activity are brought together at once in scientific data collections (SDCs). What can the development and use of shared SDCs tell us about collective activity, dynamic infrastructures, and distributed scientific work? Using examples drawn from a nascent neuroscience data collection, we examine some unique features of SDCs to illustrate that they do more than act as infrastructures for scientific research. Instead, we argue that they are themselves instantiations of Distributed Collective Practice (DCP), and as such illustrate concepts of transition, emergence, and interdependency that may not be so apparent in other kinds of DCPs. We propose that research into SDCs can yield new insights into institutional arrangements, policymaking, and authority structures in other very large-scale socio-technical networks.     

Electrochemical properties of microwave-assisted reflux-synthesized Mn<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles in different electrolytes for supercapacitor applications

The nanosized Mn₃O₄ particles were prepared by microwave-assisted reflux synthesis method. The prepared sample was characterized using various techniques such as X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman analysis, and transmission electron microscopy (TEM). Electrochemical properties of Mn₃O₄ nanoparticles were investigated using cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge analysis in different electrolytes such as 1 M KCl, 1 M Na₂SO₄, 1 M NaNO₃, and 6 M KOH electrolytes. XRD pattern reveals the formation of single-phase Mn₃O₄ nanoparticles. The FT-IR and Raman analysis also assert the formation of Mn₃O₄ nanoparticles. The TEM image shows the spherical shape particles with less than 50 nm sizes. Among all the electrolytes, the Mn₃O₄ nanoparticles possess maximum specific capacitance of 94 F g⁻¹ in 6 M KOH electrolyte calculated from CV. The order of capacitance obtained by various electrolytes is 6 M KOH > 1 M KCl > 1 M NaNO₃ > 1 M Na₂SO₄. The EIS and galvanostatic charge–discharge results further substantiate with the CV results. The cycling stability of Mn₃O₄ electrode reveals that the prepared Mn₃O₄ nanoparticles are a suitable electrode material for supercapacitor application.     

Diverse Organic Field‐Effect Transistor Sensor Responses from Two Functionalized Naphthalenetetracarboxylic Diimides and Copper Phthalocyanine Semiconductors Distinguishable Over a Wide Analyte Range

Naphthalenetetracarboxylic diimide derivatives (octyl “8” NTCDI, dimethylaminopropyl “DMP” NTCDI) and copper phthalocyanine (CuPc) are used to form a diverse organic field‐effect transistor (OFET) sensor array. CuPc and 8‐NTCDI are p‐channel and n‐channel semiconductors, respectively, showing expected and opposing responses to analytes. DMP‐NTCDI, on the other hand, because of its ionizable side chain, shows response directions and magnitudes that are not correlated to those of the other two. The result is a distinct response pattern and unambiguous recognition ability for individual analytes. The differences are even more dramatic if the time evolution of the responses is considered. The three‐response patterns obtained from representative polar, nonpolar, acidic, and basic vapors are all different, showing the potential for this approach in rapid, low‐cost electronic detection of volatile compounds.     

Influence of elephant apple powder as an adsorbent in the regeneration of fried soybean oil: Process optimization studies

In the present work, elephant apple powder (EAP) has been characterized as an adsorbent by analyzing its properties in Fourier transform infrared, scanning electron microscope, and Brunauer–Emmett–Teller surface analyser. Furthermore, the effect of EAP on the regeneration of fried soybean oil was studied by performing frying experiments with potato chips at 180 ± 5 °C for 5 hr/day in a deep fat fryer for 5 days. Oil samples were drawn periodically for evaluating the quality parameters (free fatty acid, peroxide value, iodine value, p‐anisidine value, and total polar content). The effect of process variables (contact time, heating time, and concentration of adsorbent) on the quality parameters of the fried oil was examined using response surface methodology. Results indicated that the process variables had a significant effect on the final quality of the oil. From the study, it was revealed that the quality of fried soybean oil has improved after treating with EAP.

Practical applications

The present work provides the useful information regarding the treatment of deep fried oil using a natural adsorbent. The method used in the work is cost‐effective and regenerates oil with good quality. The method of regeneration may be utilized by small and medium scale food processors as the process is simple. The results of this study showed that elephant apple powder can be used as an adsorbent to improve the quality parameters of deep fried soybean oil.     

Study of isotropic etching behavior of CR-39(DOP) polymer through ion tracks

The same sample of CR-39(DOP) polymeric foil has been exposed to ²⁰⁹Bi (11.4 MeV/u) ions at three different angles (30°, 45° and 60°) of incidence. The exposed sample has been etched chemically and various parameters of the etched tracks have been measured. The objective of the present study is to establish the isotropic etching behavior of CR-39(DOP) polymer.     

Characterization of network structure of rubber vulcanizate by monsanto moving die rheometer (MDR 2000)

While studying the curing of rubbers in a moving die rheometer, the viscous component (S″) of the measured torque increases with the formation of ionic cross-linking. But the covalent cross-linking of elastomers is manifested by a decreases in S″. The mixed cross-linking system, however, shows an initial rise in S″ value due to ionic cross-linking, followed by a decrease in S″ due to covalent cross-linking. As curing progresses, the elastic component (S′) of the measured torque in the case of a mixed cross-linking system increases in two steps: The first step is due to ionic cross-link formation, and the second step, to covalent cross-link formation. The moving die rheometer can be useful in assessing not only the extent of cross-linking, but also the type of cross-links formed during the vulcanization of rubbers. © 1993 John Wiley & Sons, Inc.