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Hydroxy apatite (HA) is a biocompatible material used as bone-substitute materials in both orthopedics and dentistry due to its excellent osteo-conductive and chemical composition similar to that of the inorganic part of bone in comparison with other implant materials . HA (S1) and Cr loaded hydroxy apatite (S2, S3, S4 and S5) of different chromium concentrations have been prepared. many techniques used to analyze the changes occurred due to the substitution. The XRD (X-ray diffraction) and FTIR (Fourier transform infrared radiation )spectroscopy were used as analytical techniques for the prepared HA and Cr loaded HA. The effect of the heat treatment on structural change of the samples was examined by DTA. It was found that all the samples have the same crystalline structure. The crystallinity of the samples decreased as the chromium ions concentration increase

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) is widely used as bio-ceramic materials and as adsorbents for separation of bio-molecules. These materials have also been used as adsorbents for heavy metals, supports and as catalysts in oxidation and dehydrogenation reactions. The catalytic performance of these materials depend on the lattice substitution of Ca sites in Hydroxyapatite structure by varied cations as Na, Mg, Sr and Mn, which result in changes in various structural pro perties as crystallinity and morphology. Pure calcium hydroxyapatite (S1) and Cr loaded hydroxyl apatite (S2, S3, S4 and S5) of different chromium concentrations have been prepared by wet precipitated method. An <i>in-vitro</i> examination is essential to investigate the mechanism of the deficient HA and tissue interface reaction by preparing SBF (Simulated Body Fluid) through the elemental and chemical analysis of Ca, P and Cr. FTIR used to analyze the samples after incubation in SBF for 24 day. PH of the samples also was measured at the first period of immersion time. At high loading of chromium ions, the formation of carbonate apatite decrease. The concentrations of the chromium in the Cr_HA crystal during the soaking in SBF are very safe dose for human

H YDROXYAPATITE is considered as one of the most effective biomaterials with general formula Ca 10 [ PO 4 [ 6 [0H , 2 [many substances have been used for doping hydroxypatite like F, Mg, CO 3 ,Zn, Bi and Na ,to improve the properties of the HA crystal. In this paper, we discuss the influence of magnesium ions on the electrical properties of the HA crystal. Pure HA (S1) and Mg loaded hydroxy apatite (S2 ,S3 and S4) of different magnesium concentrations have been prepared by wet precipitation method .The dielectric parameters) ε ('and) ε (''measured at different temperature ,relaxation time of relaxation process was calculated from the cole cole plot. The advantages of modulus studies were to recognize the conduction process and study the effect on the frequency and estimate the relaxation frequency. Conduction mechanism has been studied using alternating current measurements, analyzing their dependence on temperature and frequency .The exponent (S) was estimated to recognize the type of conduction .The activation energy studied also to confirm the conductivity measurements. The electrical measurements confirmed that as the addition of Mg increased , the conductivity of the substance would increase and this will improve the bioactivity of HA.

In the present study, we have obtained a blood hemoglobin (Hb) sensor using binary defective one-dimensional photonic crystal. The structure is composed of Air/Diamond/SiO2)NHb /Diamond/SiO2)S/SiO2 and the defect layer is filled by hemoglobin solution. The numerical calculations are based on transfer matrix method (TMM). The defect peak showed well shifting of the defect peak frequency by increasing the hemoglobin concentration; the wavelength shifted due to the change of hemoglobin concentration; from 679.5 nm at the 0g/dL to 682.3 nm at 28.7 g/dL. The presented idea is very simple, and can potentially attract a wider audience when one considers the fact of constantly rising interest of the scientific community (especially biologists and physicians) in the diagnostic methods utilizing different types of the optical phenomena.

This paper is an attempt to investigate the effect of neodymium yag ( Nd:YAG) laser exposure during eye treatment (1064nm, 0.01w/cm 2 , spot size 450µm, duration time 9 n sec., 30 pulses per sec and time exposure, 0.25 (group A) and 0.1 sec (group B)). We intend to measure the dielectric properties of eye tissues and correlate them with structure. Values of the relative permittivity, dielectric loss and conductivity έ, ε'' & , are measured for various rabbit ocular tissues (cornea, lens and retina) at the frequency range 100Hz -100kHz before and after laser exposure. The aim of this work is to test the functional state of the eye tissues exposed to laser beam of the same intensity and duration as that used in lens posterior capsulotomy after cataract surgery, by the use of dielectric method. We tried to adapt the physical conditions surrounding the exposed eye during exposure. The obtained results showed that, for the whole eye, as well as for all eye tissues, both values of permittivity and conductivity showed remarkable decreases than normal values, immediately after laser exposure, for both group A & B and this reduction begins to diminish with days after exposure approaching normal values approximately after 8 days of exposure. It is evident that, although laser interacts with all cell membrane structures responsible for transport phenomena leading to changes in the dielectric properties, this interaction depends on the tissue type, special function of membrane and magnitude of exposure power and time of exposure which must accurately considered during choosing the laser treatment conditions and the tissue to be treated. Introduction:

The aim of the present study was to find out the effects of low frequency electromagnetic field (EMF) 50 Hz -10 mT on the rat electroencephalogram (EEG) recorded from the rat brain cortex and from the skull surface. The rats were, whole body, exposed to this EMF intensity one hour daily for 7 days. Recovery study was done after one week from stopping the EMF exposure. The effects of the filed were estimated by compression of the averaged EEG frequency spectra in the range of frequencies between 0.2 -0.7 Hz and by comparison of amplitude of EEG waves in control, exposed to EMF and recovery animals. Statistically significant effects of EMF were observed both in EEG amplitude and power reduction at most EEG frequencies. Also, noticeable variations were observed in normal values of maximum amplitude and number of successive EEG epochs recorded from brain and skull surfaces after exposure to ELF magnetic fields. These results show that a weak low EMF can influence the spontaneous electrical rat brain activity in the animals subjected to the EMF.

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