Informatics Publishing Limited

N. Nandi ¹, R. K. Roy ¹, Anupriya ¹, S. Upadhaya ¹, D. Vollhardt ²

Affiliations
1 Chemistry Department, Birla Institute of Technology and Science, Pilani, Rajasthan, 333 031, IN
2 Max-Planck-Institute fur Kolloid-und Grenzflaechenforschung, D-14424 Postdam/Golm, DE

Abstract

An Effective Pair Potential (EPP) theory is used to study relation between the molecular chiral structure of a phospholipid (Dipalmitoyl phosphatidyl choline; DPPC) and the shape of the mesoscopic domain composed of DPPC. It is experimentally known that the monolayers of DPPC in the condensed phase exhibit the formation of triskellion shaped domains. The curvature of the arms of the triskellions has specific handedness depending on the chirality of the constituent molecule. The study uses an equivalent description of the groups attached to the chiral center and calculates the mutual orientation of a pair of molecules (enantiomeric and racemic pairs). The pair potential is calculated using Lennard Jones potential. Also, the electrial interaction is computed using semi-empirical approach. Based on the minimum energy arrangement, the handedness of the aggregates and their pair potential are predicted. Theoretically obtained results are compared with the experimental results and also with the previously obtained coarse-grained description of the molecule. The study uses no adjustable parameter and uses the microscopic information obtained from X-ray diffraction data. It shows that the equivalent sphere description of the molecule can fairly describe the mesoscopic features of the domains such as the handedness based on the pair potential calculation.

Keywords

Chiral Interaction, Monolayer, Effective Pair Potential.

Full Text

     

K. Usharani ¹, Vijayalakshmi ², R. K. Roy ², Jamuna Prakash ¹

Affiliations
1 Department of Studies in Food Science and Nutrition, University of Mysore, Manasagangotri, Mysore -570 006, IN
2 Bharath Hospital and Institute of Oncology, Hebbal, Mysore, IN

Abstract

Cancer in simple terms is an uncontrolled growth of cells. These are cells that have acquired ability to multiply and spread without restriction. Any cell tissue or organ in the body can be affected. Cancer is a set of disease states rather than a single disease with devastating impacts in terms of mortality as well as physical and psychological morbidity. The growth of a tumour leads to profound alterations of body organs and functions. As a result of this a poorly understood syndrome, "cachexia" develops. Cancer patients frequently lose body weight and anorexia is one of the prime determinants of weight loss. Pre-treatment weight loss is associated with decreased median survival and response to therapy. The three types of therapy used in the treatment of cancer are surgery, radiotherapy and chemotherapy.

Full Text

     

J. S. Khuraijam ¹, R. K. Roy ¹

Affiliations
1 Botanic Garden, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226 001, IN

Abstract

Cycads are an ancient group of plants which have survived three mass extinctions. They are dioecious, perennial, palm-like trees or shrubs with woody trunk above the ground or subterranean. They are a relict group of seed plants that evolved in the late Carboniferous or early Permian around 300 million years ago. With the ever-increasing interest in cycad taxonomy over last two decades, the number of new species of cycad has increased significantly.

Full Text

   

R. K. Roy ¹, A. K. Panda ¹, A. Mitra ¹

Affiliations
1 NDE & Magnetic Materials Group, CSIR - National Metallurgical Laboratory, Jamshedpur 831007, IN

Abstract

The joining behaviour between stainless steel and copper has an importance in scientific and engineering applications such as high energy ring vacuum chambers and International Thermonuclear Fusion Experiment Reactor (ITER). In this research, the rapidly solidified foils of nominal composition 50Cu-40Mn-10Ni (C50) are used as a filler alloy for brazing between stainless steel (304 SS) and copper (Cu) plates. It is examined that C50 foil makes a good contact joint between two dissimilar metal plates of different thermal conductivities. The brazed region is mostly free from any porosities and intermetallic compounds, emphasizing on the distribution of solid solution phases. It causes high bonding strength of 304 SS-Cu butt joint at low brazing temperature (B_T=920°C) with a fracture at the joint area. On the other hand, the fracture occurs at Cu base metal for B_T = 980°C. The fractography also shows the presence of several dimples at Cu substrate and severely deformed region at stainless steel substrate, representing a good quality bonding between 304SS and Cu plates.

Keywords

Brazing, Diffusion, Electron Microscopy, Solid Solution Phases, Bonding Strength.

Full Text