//--> Workshops & conferences in SNBNCBS
     
 
   
   
 
One day Symposium, S.N. Bose National Centre for Basic Sciences
  
     
  Schedule:  
     
  Welcome note by Abhijit Mookerjee (9.30 - 9.35)
Address by UNANST group head, A. K. Raychaudhury (9.35 - 9.50)		  
     
  Session I (chaired by Surajit Sengupta)  
     
  Jaydeb Chakrabarty (9.50 - 10.10)
Samir Pal (10.10 - 10.30)
Ranjit Biswas (10.30 - 10.50)
Partha Guha (10.50 - 11.10)		  
     
  Tea (11.10 - 11.30)  
     
  Session II (chaired by Samir Pal)  
     
  P. A. Sreeram (11.30 - 11.50)
D. Das (11.50 - 12.10)
A. Patra (12.10 - 12.30)
A. Saha (12.30 - 12.50)		  
     
  Lunch (12.50 - 14.00)  
     
  Session III (chaired by Ranjit Biswas)  
     
  Priya Mahadevan (14.00 - 14.20)
Ashim Ray (14.20 - 14.40)
P. Singha Deo (14.40 - 15.00)
Surajit Sengupta (15.00 - 15.20)
P.K. Mukhopadhyay (15.20 - 15.40)		  
     
  Tea (15.40 - 16.00)  
     
  Session IV (chaired by Priya Mahadevan)  
     
  Barnali Ghosh (16.00 - 16.20)
Kalyan Mandal (16.20 - 16.40)
S. Dattagupta (16.40 - 17.00)
Abhijit Mookerjee (17.00 - 17.20)
A. K. Raychaudhury (17.20 - 17.40)		  
     
  Concluding remarks (by S. Dattagupta, A. K. Raychaudhury) and High tea  
     
     
 
Titles and abstracts
  
     
Simple Physics of Complicated Materials: Nano-dispersions and Flow sensors of nanoassembly
Dr. Jaydeb Chakraborti
     
 
Simple Physics of Complicated Materials: Nano-dispersions and Flow sensors of nanoassembly
1. We carry out MC simulations of e ective interaction between a pair of "solvophobic" solute particles in a subcritical liquid solvent bath. The solute particles can self-aggregate into nano-sized cluster which
may be relevant in making stable nano-dispersions.
2. An assembly of nano gold particles can act as a ow sensor device. We shall discuss the experiment and simple theoretical model to understand qualitatively the experimental results.
  
     
     
Biological Macromolecules in Nano-cages
Dr. Samir Pal
     
 
Biomolecules in nanometer-sized cages are quite interesting and relevant as the system mimic spatial restriction imposed on the macromolecules in a real physiological environment. The structural, functional and dynamical aspects of proteins and DNA in aqueous nanocages will be discussed.
  
     
     
Ranjit Biswas (Not received)
  
     
     
Dynamics of DNA
Dr. Partha Guha
     
  We present the intrinsic dynamics of DNA in terms of the Kirchho elastic rod equation and nonlinear elasticity theory.  
     
     
Understanding the operation of Dynamic Force Microscope.
Dr. P. A. Sreeram
     
     
Characterization of nanocrystalline materials by nuclear techniques
Dipankar Das
UGC-DAE Consortium for Scienti c Research, Kolkata 700 098
     
  Nanocrystalline materials are known to have di erent physical and chemical properties compared with the same in the bulk state. The usefulness of nuclear techniques e.g. Mssbauer spectroscopy and positron
annihilation lifetime spectroscopy in probing unusual properties of the nanomaterials will be discussed by taking speci c examples of ferrites, composites and gels.		  
     
     
Understanding the photoluminescence properties of nano- materials
Amitava Patra
Sol-Gel Division, Central Glass & Ceramic Research Institute, Jadavpur, Kolkata 700 032, India
     
 

The study of nanoscale matter-radiation interactions o ers numerous opportunities for both fundamental research and technological applications in photonics and biophotonics [1-9]. Nano-enviornments play key roles in controlling the relaxation dynamics. We are currently exploring the understanding the luminescence properties of rare-earth ions
in oxide nano environments. From the fundamental point of view, the
physical understanding of emission and upconverted emission of rareearth
ions/transition metal ions in oxide nanocrystals and the way it changes with size, crystal phase and concentration is very important.
The changes observed in the lifetime of excited state of rare-earth ion
is mainly due to modi cations of radiative and nonradiative relaxation
processes due to crystal structure and crystal size respectively. The
luminescence eciency of Eu-complex doped in di erent polymers has
been studied. The energy transfer study between CdS nanoparticles
with dye and the role of capping agent on the emission properties of
NC?s have been investigated.

1. Amitava Patra, Chem. Phys. Lett., 387 (2004) 35.
2. Amitava Patra, Ind. Jour. Phys, 78A (2004) 43.
3. S. Saha, P. S. Chowdhury and A. Patra, J. Phys. Chem. B,
109(2005) 2699.
4. P. S. Chowdhury, S. Saha and A. Patra, Chem. Phys. Lett, 405
(2005) 393.
5. P. S. Chowdhury, S. Saha and A. Patra, Solid State Commu, 131
(2004) 785.
6. A. Patra, Solid State Commu, 132 (2004) 299.
7. P. S. Chowdhury and A. Patra, Chem. Phys. Lett, 2005 (accepted,
July, 2005).
8. A. Patra, P. Ghosh, P. Saha Chowdhury, et.al, J. Phys. Chem.
B, 109 (2005) 10142.
9. A. Patra, S. Saha, et.al., Chem. Phys. Lett, 407 (2005) 477.

  
     
     
Synthesis of surface capped uorescent nanoparticles and its interaction with biomolecules
A. Saha
UGC-DAE Consortium for Scienti c Research, Kolkata Centre III/LB-
8 Bidhannagar, Kolkata 700 098
     
  There has been considerable interest in semiconductor nanoparticles
or colloidal quantum dots due the novel electronic and optical properties
arising out of quantum con nement e ects. The drive for expanding
our understanding of semiconductor nanoparticles has been
spearheaded by potential applications of these materials in various optoelectronic
devices. Lately, surface modi cation of
uorescent semiconductor
nanoparticles by biomolecules like peptides and nucleic acids
have added a new dimension to the nanoparticle research with respect
to their biological applications. Utilizing these nanoparticle bioconjugates
for accurate and sensitive determination of water soluble analytes
such as toxins, small molecule explosives, ionic species, and various
biomolecules like nucleic acids and proteins is one of the most
cherished scienti c goals with wide rami cations in disease diagnosis,
drug development and defence applications. The e ectiveness of biofunctionalized
semiconductor nanoparticle probes in determination of
proteins and nucleic acids as compared to conventional techniques using
organic
uorophores has been quite vividly demonstrated by earlier
workers. In contrast, little attention has been paid to understand the
role of constituents of these macromolecules in interaction with the
semiconductor nanoparticles. Here, mainly syntheses of CdS nanoparticles
by chemical and gamma irradiation routes and its interaction
with amino acids will be highlighted.		  
     
     
Doping in Nanostructured Systems
  
Dr. Priya Mahadevan
  
     
  I will present an overview of doping in nanostructured materials, discussing
the issues from a theoretical viewpoint. Some of our results on
doping in carbon nanotubes will be discussed.		  
     
     
Fock-Darwin like states in a quantum ring.
Dr. Ashim Roy
     
  We have considered a 2D ring with an Aharonov-Bohm
ux. The single
particle Hamiltonian is solved exactly under two di erent boundary
conditions which correspond to a mesoscopic superconducting ring and
a persistent current ring. Both these phenomena can be observed experimentally
in nano to micron sized rings. Just as the Fock-Darwin
states have a wide range of applications in case of quantum dots, we
believe that the states that we have derived will nd a wide range of
applications in quantum rings.		  
     
     
Electronic properties in mesoscopic systems
Dr. P. Singha Deo
     
  At subkelvin temperatures and in micron to nano size materials, the
electronic properties are strikingly di erent from that in the bulk. Some
exciting aspects will be presented.		  
     
     
Strategies for understanding phase transitions in small clusters and
con ned systems.
Dr. Surajit Sengupta
     
  Small systems behave di erently from bulk. The melting point of certain
small clusters of atoms are very di erent from their bulk values.
However, does it make sense to talk about phase transitions in systems
which are de nitely not in the thermodynamic limit? In this short
talk I will try to discuss certain strategies which may help us to make
progress in trying to understand the issues involved.		  
     
     
Dr. P. K. Mukhopadhyay (Not received)
     
     
Synthesis and Characterisation of nanostructured lms and nanowires
of complex oxides by wet chemical route
Dr. Barnali Ghosh
Dr. Kalyan Mandal (Not received)
DIAMAGNETISM IN A PARABOLIC WELL
Prof. Sushanta Dattagupta
     
  I will discuss the quantum calculation of Landau Diamagnetism in a
con ned geometry of a parabolic well. The resuts are applicable to a
nondegenerate two-dimensional electron gas con ned within a quantum
well.		  
     
     
Electronic and Magnetic structure of Mn(x)As(y) clusters
Prof. Abhijit Mookerjee
     
  We shall report a study of the Electronic and Magnetic structures of
Mn(x)As(y) clusters using a rst-principles Molecular Dynamics study
based on local spin-density approximation and using recently proposed
soft pseudopotentials appropriate to transition metal clusters.		  
     
     
How stable are nanowires?
Prof. A.K. Raychaudhury
     
  We have measured the low frequency (1mHz f 10Hz) resistance
uctuations
in metallic nanowires (diameter 15nm to 200nm) in the temperature
range 77K to 400K. The nanowires were grown electrochemically
in polycarbonate membranes and the measurements were carried out
in arrays of nanowires by retaining them in the membrane. A largeuctuation in excess of conventional 1/f noise was found which peaks
beyond a certain temperature. The
uctuations with a signi cant low
frequency component ( 1=f3=2) arise when the diameter of the wire <
15nm and vanishes rapidly as the diameter is increased. We argue that
Rayleigh-Plateau instability is the likely cause of this excess noise.		  
     
     
         
         
 
 
S.N. Bose National Centre for Basic Sciences, Sector - III, Block - JD, Salt Lake, Kolkata - 700 098
Phone: +91 (033) 2335 5706-8 Fax : +91 (033) 2335 3477
Developed by Amitava Bhattacharyya & Santosh K. Singh