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Objectives: The aims of present study were to evaluate nickel and chromium ions concentrations in salivary and serum samples from patients treated with fixed orthodontic appliances and their possible influences on hepatic enzymes. Materials and methods: Saliva and blood samples were collected from 36 patients ranging in age from 12 to 24 years. Three samples of saliva and two samples of blood were obtained. First saliva and blood samples were collected before inserting fixed appliances. Second salivary samples were collected at 1 week, third salivary sample and second blood sample after 4 weeks of appliance insertion. Serum was prepared by centrifuging blood samples at 3000 rpm for 10 minutes. Spectrophotometric determinations were carried out using electrothermal atomic absorption spectrophotometry. Results and conclusion: In serum, significant increase in Ni and Cr ion concentration occurred in samples collected after 4 weeks. In saliva samples, nickel and chromium reached their highest lavels in first week. Mean liver function enzymes SGOT and SGPT were also significantly increased in 4 weeks. Fixed orthodontic appliances release measurable amount of nickel and chromium when placed in mouth, but this increase does not reach toxic levels for nickel and chromium in saliva and serum to cause harmful effects in human beings.

The lattice model of Coulomb Glass in two dimensions with box-type random field distribution is studied at zero temperature for system size upto 96 2 . To obtain the minimum energy state we annealed the system using Monte Carlo simulation followed by further minimization using clusterflipping. The values of the critical exponents are determined using the standard finite size scaling. We found that the correlation length ξ diverges with an exponent ν = 1.0 at the critical disorder Wc = 0.2253 and that χ dis ≈ ξ 4−η withη = 2 for the disconnected susceptibility. The staggered magnetization behaves discontinuously around the transition and the critical exponent of magnetization β = 0. The probability distribution of the staggered magnetization shows a three peak structure which is a characteristic feature for the phase coexistence at first-order phase transition. In addition to this, at the critical disorder we have also studied the properties of the domain for different system sizes. In contradiction with the Imry-Ma arguments, we found pinned and noncompact domains where most of the random field energy was contained in the domain wall. Our results are also inconsistent with Binder's roughening picture.

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Parkinson disease alters the information patterns in movement related pathways in brain. Experimental results performed on rats show that the activity patterns changes from single spike activity to mixed burst mode in Parkinson disease. However the cause of this change in activity pattern is not yet completely understood. Subthalamic nucleus is one of the main nuclei involved in the origin of motor dysfunction in Parkinson disease. In this paper, a single compartment conductance based model is considered which focuses on subthalamic nucleus and synaptic input from globus pallidus (external). This model shows highly nonlinear behavior with respect to various intrinsic parameters. Behavior of model has been presented with the help of activity patterns generated in healthy and Parkinson condition. These patterns have been compared by calculating their correlation coefficient for different values of intrinsic parameters. Results display that the activity patterns are very sensitive to various intrinsic parameters and calcium shows some promising results which provide insights into the motor dysfunction.