A group theoretic construction of highly nonlinear substitution box and its applications in image encryption

Substitution box is the most significant component of block cipher. The property of nonlinearity is of great importance for the design of secure substitution boxes. Therefore, it is necessary to develop new methods for the production of substitution boxes with a high non-linearity score. In this paper, we have introduced a novel group theoretic method to construct a robust S-box with non-linearity score 113.75 greater than that of AES S-box. The performance of generated S-box is found to be excellent, when examined through various other well-known algebraic criteria such as strict avalanche criterion, bit independence criterion, differential uniformity and linear approximation probability. The suitability of proposed S-box is tested for image encryption applications through different statistical analyses. We got very encouraging outcomes from all these examinations which certify that the generated S-box meets all the criteria needed to be reliable for secure communication and image encryption.

     

How does justice matter in online retailers’ reputation and purchase intentions: an empirical study of China

In recent years, online shopping has been proliferated around the world. Online retailers’ reputation and purchase intentions are critical for survival and profitability of any online store. Thus, this study proposes a research framework to examine the perceived justice effects on customers purchase intention and online retailers’ reputation. A confirmatory factor analysis was conducted to demonstrate the reliability and validity of the measurement model, and the structural equation modelling technique was used to test the research model. The hypothesised model was validated empirically using data collected from 383 online shopping customers in China. The results indicated that perceived procedural, distributive and interactional justice components were strong predictors of customers purchase intention and online retailers’ reputation while online retailers’ reputation had significant effects on purchase intentions. Finally, theoretical and managerial implications are also presented in the paper.     

Preparation and characterization of pH sensitive crosslinked Linseed polysaccharides-co-acrylic acid/methacrylic acid hydrogels for controlled delivery of ketoprofen

Some pH responsive polymeric matrix of Linseed (Linum usitatissimum), L. hydrogel (LSH) was prepared by free radical polymerization using potassium persulfate (KPS) as an initiator, N,N-methylene bisacrylamide (MBA) as a crosslinker, acrylic acid (AA) and methacrylic acid (MAA) as monomers; while ketoprofen was used as a model drug. Different formulations of LSH-co-AA and LSH-co-MAA were formulated by varying the concentration of crosslinker and monomers. Structures obtained were thoroughly characterized using Fourier transforms infrared (FTIR) spectroscopy, XRD analysis and Scanning electron microscopy. Sol-gel fractions, porosity of the materials and ketoprofen loading capacity were also measured. Swelling and in vitro drug release studies were conducted at simulated gastric fluids, i.e., pH 1.2 and 7.4. FTIR evaluation confirmed successful grafting of AA and MAA to LSH backbone. XRD studies showed retention of crystalline structure of ketoprofen in LSH-co-AA and its amorphous dispersion in LSH-co-MAA. Gel content was increased by increasing MBA and monomer content; whereas porosity of hydrogel was increased by increasing monomer concentration and decreased by increasing MBA content. Swelling of copolymer hydrogels was high at pH 7.4 and low at pH 1.2. Ketoprofen release showed an increasing trend by increasing monomer content; however it was decreased with increasing MBA content. Sustained release of ketoprofen was noted from copolymers and release followed Korsmeyer-Peppas model.     

Studies on marigold seed oil and seed meal

The fixed oil (26%) of the seeds of Marigold (Calendula officinalis) locally known as “Gul-e-Ashrafi” growing around the laboratories, was studied for its physico-chemical properties. Fatty acid composition of the seed oil as determined by gaschromatography and UV-spectroscopy showed the presence of lauric (3.90%), myristic (3.58%), palmitic (14.96%), stearic (10.13%), palmito-oleic (4.55%), oleic (16.26%), linoleic (39.45%) and linolenic (7.15%) acids. In the seed oil, conjugated acid is present to the extent of 4.5% whereas the percentage of non-conjugated acid (linolenic acid) is only 2.65%. The residual meal after the extraction of oil was also studied for its proteins (18%) and amino acids composition.     

Gender, Gender Relations, and the Social Dynamics of Children's Conversations.

The authors investigated the effects of gender on the social dynamics and outcomes of conversations involving 120 children (mean age = 8 years 7 months). Children were taught particular values for different shaped counters and placed in same-gender or mixed-gender pairs with children who were taught different values. Pairs were asked to add the counters together to make a total of 100. Conversations were coded in terms of communication acts and simultaneous speech acts. Boys used more controlling acts overall and more negative interruptions in mixed-gender pairs. Girls used more affiliating acts. All children used more collaborative communication in same-gender pairings. Children whose perspective dominated used more controlling and comparatively fewer affiliating acts. When children reached a compromise, conversations were more collaborative. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Off-diagonal magnetoimpedance in NiFe-Au-NiFe layered film and its application to linear magnetic sensors

We have measured the field dependence of the off-diagonal impedance in the megahertz frequency range for a NiFe-Au-NiFe layered film using a helical microcoil. The film and the coil were deposited by means of radio-frequency sputtering, and a transverse anisotropy in magnetic layers was established by applying a dc magnetic field during the deposition and by postproduction annealing. The film had 5 mm length, 50 /spl mu/m width, and 1.5 /spl mu/m total thickness. The helical microcoil had 23 turns with a 50 /spl mu/m turn width. We applied high-frequency excitation by means of the coil current and measured the induced voltage across the film stripe. This voltage response is directly proportional to the off-diagonal component of the total impedance tensor. We found that the plots of the real and imaginary parts of the off-diagonal impedance, as functions of the applied dc magnetic field, are antisymmetrical with respect to the field direction. The dc bias current through the film plays an important role: without the bias current, the measured signal is very small and irregular. The field antisymmetry demonstrated by the off-diagonal impedance can be utilized in highly sensitive and linear magnetic sensors, and we discuss the principles of operation of such sensors here.     

Molecular dynamics study of thermal properties of noble metals

Molecular dynamics simulations have been applied to investigate thermal properties of Ag and Au. Semi-empirical potentials, based on the embedded atom method (EAM) have been employed to calculate lattice parameter, energy per atom, mean square displacements and radial distribution function for the two metals. Thermal properties like specific heat, thermal coefficient of linear expansion and melting temperature are deduced from the calculated parameters. Results are found to compare well with the experimental results.