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With the rapid increase of efficiency up to 23.7% during the past few years, hybrid organic-inorganic metal halide perovskite solar cells (PSCs) have become a research “hot spot” for many solar cell researchers. The perovskite materials show various advantages due to unique characteristics of perovskite materials, such as high photo-to-electric conversion efficiency, direct band gap, high light absorption coefficient, high charge-carrier mobility and long electron-hole electron transport distance. The low-cost fabrication techniques together with the high efficiency makes PSCs comparable with Si-based solar cells. This paper begins with the discussion of crystal structures of perovskite based on recent research findings. The following part of this paper discussion of synthetic process of lead iodide perovskite materials from lead-acid battery and Harvesting material from the anodes and cathodes of car battery; synthesizing PbI2 from the collected materials and compare with pure Lead iodide to know the absolute by XRD peak, depositing lead iodide perovskite nanocrystals. Efficient flexible PSCs are fabricated onto FTO glass substrate by a two-step coating method under ambient condition. By adjusting the concentration of precursor CH3NH3I (MAI), the morphology and thickness of perovskite layer is effectively tailored, according to SEM analysis and using TiO2 as electron transport layer instead of ZnO and CuI instead of spiro-OMeTAD as hole transport layer.

The world energy demand is continuously increasing. Due to environment issues, global warming, and other issues, there is a need for clean sources of energy, sustainable energy, i.e. renewable energy technologies. Photovoltaic (PV) technology employing solar energy is regarded as rather most promising and efficient technology among all the renewable energy industries. The further improvement in the efficiency and reliability and also reduction in cost are in great demand, for the healthy development of global economy. Among the third generation solar cells, perovskite cells have attracted a lot of attention due to their high efficiency and low cost construction methods. In this research, low-cost perovskite solar cell (PSC) was prepared, and its photovoltaic performance was investigated. In this project, we tried to get rid of some structures or materials which are harm to the environment. i.e. car batteries. By using lead sheets (from recycled car battery). However, by reusing car batteries we will avoid the disposal of toxic battery materials and provide an alternative, readily-available lead source for fabricating PSC. Perovskite solar cell was prepared by two-steps spin coating solution technique on glass substrates at various thermal annealing deposition temperature. Then photovoltaic performance of PSC was investigated, together with the stability of PSC, and the effect of annealing temperature of perovskite layer on performance of perovskite solar cell. The efficiency of the cell, subjected to thermal annealing at temperature of 100, for 12 minutes was (14.8%). Then the efficiency of the cell altered to (12.4%), after 105 days ageing at room temperature.

In this paper we study the periodic solution of nonlinear system of differential equations depending on the gamma distribution by using the numerical analytic method to investigate periodic solutions of ordinary differential equation which given by Samoilenko A. M. .These investigations lead us to improving and extending this method. Also we expand the results gained by Samoilenko A. M. to change the periodic system of nonlinear differential equations to periodic system of nonlinear differential equations depending the on gamma distribution.

Summary Objective Dentine hypersensitivity may occur due to loss of covering enamel and/or loss of cementum after gingival recession, resulting in exposure of cervical dentine and patency of dentinal tubules. The effect of thermally cooled pulsed neodymium:yttrium–aluminium-garnet (Nd:YAG) laser on the permeability and structural appearance of the root canal wall was investigated in vitro. The aim of this study was to compare the occluding effect of Nd:YAG laser with that of sensodyne on exposed dentine. Material and methods Forty freshly extracted human maxillary anterior teeth were collected at random. Root canal obturations were performed using master apical file no. 60 k-type for obturated teeth. All teeth were stored in 100% humidity at 37 °C for 48 h to allow time for the sealer to set. Dentine of 35 teeth was exposed by removing the cementum, and the remaining five teeth represented a negative control group. Specimens were examined using stereomicroscopy to show the surface topography of the dentine substrate before and after treatment with Nd:YAG laser or sensodyne. Results A double-blind technique was used when taking measurements of ink penetration (in mm) for each group. Teeth treated by Nd:YAG laser showed the least ink penetration, followed by teeth treated by sensodyne. The positive control group demonstrated complete ink penetration and the negative control group showed no ink penetration. Stereomicroscopic examination of specimens treated with Nd:YAG laser showed deposition on the dentinal surface, and specimens treated with sensodyne showed partial deposition. Untreated specimens were free of deposition and the tubules remained patent. Conclusion There is no significant difference in the occluding effect of Nd:YAG laser and sensodyne toothpaste. Both treatments have a promising effect on the reduction of permeation through exposed dentinal tubules. However, the occluding effect of Nd:YAG laser occurs within seconds whereas that of sensodyne takes at least 3 weeks.

Antibacterial activity of ethanolic and aqueous extracts of Capsella Bursa were carried out against eight different species of bacteria, Gram-positive Staphylococcus aureus and Enterococcus fecalis and Gram-negative Escherichia coli, Proteus vulgaris, Serratia marcescens,Acinitobacter bumani, Klebsiella pneumoniae and Pseudomonas aeruginosa. It is active antibacterial only against gram-negative bacteria. The ethanolic and aqueous extract from the same plant showed different activities; the aqueous extract (hot) showed the same or greater activity than the ethanolic extract. by disc diffusion, hot aqueous extract 2000 and 3000 µg/ml inhibition zone was observed against five gram negative pathogens in almost similar pattern . Ethanolic extract was active only against Ps.aeruginosa and K. pneumoniae. The MIC and MBC values of the ethanolic and aqueous extract of Capsella Bursa was active against most bacteria. All isolates were tested by different concentration of sub-MIC of aqueous and ethanolic extracts give different activities of these concentrations to inhibit or omitting the ability of those isolates to produce virulence factors (DNase, Haemolysin production and Lipase production). Finally, the Broth dilution assay showed larger activity than the disc diffusion method.