we study how to control the dynamics of excitable systems by using the phase control technique.We study how to control nonlinear semiconductor laser dynamics with optoelectronic feedback using the phase control method. The phase control method uses the phase difference between a small.added frequenc y and the main driving frequency to suppress chaos, which leads to various periodic orbits. The experimental studying for the evaluation of chaos modulation behavior are considered in two conditions, the first condition, when one frequency of the external perturbation is varied, secondly, when two of these perturbations are changed. The chaotic system becomes regular under one frequency or two freq

Laser cleaning of materials’ surfaces implies the removal of deposited pollutants without affecting the material. Nanosecond Nd:YAG pulsed laser, operating at 1064 nm and 532nm, was utilized. Different laser intensities and number of pulses were used on metallic and non-metallic surfaces under O2 and Ar environments to remove metal oxide and crust. Cleaning efficiency was studied by optical microscope. The results indicated the superiority of 1064 nm over the 532 nm wavelength without any detectable damage to materials’ surfaces. Marble cleaned in Oxygen gas environment was better than in Ar gas.

In this work the analysis of laser beam profile system ,using a two dimensional CCD (Charge Coupled Device) arrays, is established. The system is capable of producing video graphics that give a two dimensional image of laser beam. The video graphics system creates color distribution that represent the intensity distribution of the laser beam or the energy profile of the beam. The software used is capable of analyzing and displaying the profile in four different methods that is , color code intensity contouring , intensity shareholding, intensity cross section along two dimension x-y, and three dimensional plot of the beam intensity given in the same display.

Pyogenic granuloma is one of the inflammatory hyperplasia seen in the oral cavity. The
present study included 10 patients with pyogenic granuloma, involving 4 males and 6 females with 1:1.5
male to female ratio. Patient ages ranged from 5 to 85 years (mean, 30 years) and half of the lesions had
pedunculated base, with surface ulceration in 10% of cases. Treatment consisted of resection, using 810
nm diode lasers. Eight patients were anesthetized during the surgical operation by local infiltration of
anesthesia. Only three patients reported mild post-operative pain within the first 24 hours of the healing
period. During the surgical operation there was no significant bleeding so clear surgical field. There was
no blee

Pyogenic granuloma is one of the inflammatory hyperplasia seen in the oral cavity. The
present study included 10 patients with pyogenic granuloma, involving 4 males and 6 females with 1:1.5
male to female ratio. Patient ages ranged from 5 to 85 years (mean, 30 years) and half of the lesions had
pedunculated base, with surface ulceration in 10% of cases. Treatment consisted of resection, using 810
nm diode lasers. Eight patients were anesthetized during the surgical operation by local infiltration of
anesthesia. Only three patients reported mild post-operative pain within the first 24 hours of the healing
period. During the surgical operation there was no significant bleeding so clear surgical field. There was
no blee

In this paper, ferric oxide nanoparticles) Fe₂O₃ NPs( were synthesized directly on a quartz substrate in vacuum by pulse laser deposition technique using Nd:YAG laser at different energies (171, 201,363 mJ/pulse). The slides were then heated to 700^o C for 1 hour. The structural, optical, morphological, and electrical properties were studied. The optical properties indicated that the prepared thin films have an energy gap ranging from 2.28 to 2.04 eV. The XRD results showed no lattice impurities for other iron oxide phases, confirming that all particles were transformed into the α-Fe₂O₃ phase during the heating process. The AFM results indicated the dependence of nanoparticles size o

     In this study, cadmium oxide (CdO) was deposited on glass bases by thermal chemical spraying technique at three concentrations (0.05, 0.1, 0.15) M and then was irradiated by CO₂ laser with 10.6 μm wave length and 1W power. The results of the atomic force microscope AFM test showed that the surfaces of these CdO thin films were homogenous and that the laser irradiated effect resulted in decreasing the roughness of the surface as well as the heights of the granular peaks, indicating a greater uniformity and homogeneity of the surfaces. The optical properties were studied to determine laser effect. The results of optical tests of these thin films showed that the photoluminescence spectra and absorption s

Background: A diverse group of bacteria live in biofilms in the oral cavity. On dental surfaces biofilms form plaque that is potentially involved in caries and periodontal diseases. Periodic studying of plaque microflora and their antimicrobial sensitivity patterns strongly affects the clinical practice in plaque-induced oral diseases. Materials and methods: Dental plaque samples were collected from 22 patients having ages ranged between 33 and 49 years with gingivitis that met the study criteria. Plaque, gingival and gingival bleeding indices (PI, GI, GBI) were measured for each patient. Laboratory procedures included microbiological examination of plaque samples followed by antibiotic sensitivity testing using disc diffusion method were

Background: Tooth extraction is one of the most commonly performed procedures in dentistry. It is usually a traumatic process often resulting in immediate destruction and loss of alveolar bone and surrounding soft tissues. Various instruments have been described to perform atraumatic extractions which can prevent damage to the paradental structures. The physics forceps is one of those innovations in dental extraction technologies that claim to provide an efficient means for atraumatic dental extractions. Materials and method: A randomized clinical trial was conducted to compare the physics forceps with the conventional forceps for the removal of 28 mandibular single rooted teeth under the following parameters: incidence of crown, root, b