Structural, Optical, and Electrical Parameters of Doped PVA/PVP Blend with TPAI or THAI Salt

The 70% polyvinyl alcohol/30% polyvinyl pyrrolidone (PVA/PVP) polymer blends, with different weight ratios of tetrapropylammonium iodide (TPAI) or tetrahexylammonium iodide (THAI) salt, were prepared using dimethyl sulfoxide (DMSO) as a solvent. The X-ray diffraction technique was used to trace the crystalline nature of the formed blends. The SEM and EDS techniques were applied to figure out the morphology of the blends. The variation in the FTIR vibrational bands was used to investigate the chemical composition and the effect of different salt doping on the functional groups of the host blend. The influence of the salt type (TPAI or THAI) and its ratio on the linear and nonlinear optical parameters for the doped blends were investigated in detail. Absorbance and reflectance are highly enhanced in the UV region reaching a maximum for the blend with 24% TPAI or THAI; so, it can be employed as shielding materials for UVA and UVB types. The direct (5.1 eV) and indirect (4.8 eV) optical bandgaps were reduced continuously to (3.52, 3.63 eV) and (3.45, 3.51 eV) while increasing the content of TPAI or THAI, respectively. The blend doped with 24% wt TPAI exhibited the highest refractive index (around 3.5 in 400-800 nm). The DC conductivity is affected by the content and type of salt, its dispersion, and blend-salt interaction. The activation energies of different blends were obtained by applying the Arrhenius formula.

Development of Perovskite (MACl)0.33FA0.99MA0.01Pb(I0.99Br0.01)3 Solar Cells via n-Octylammonium Iodide Surface Passivation

The influence of n-octylammonium iodide (OAI, passive layer) on the types of phases formed in a (MACl)_0.33FA_0.99MA_0.01Pb(I_0.99Br_0.01)₃ perovskite film was studied using X-ray diffraction. Using UV spectrophotometric techniques, it was determined how varied OAI additive layer ratios affected the linear and nonlinear optical characteristics of glass substrates/FTO/compact TiO₂/mesoporous TiO₂/(MACl)_0.33FA_0.99MA_0.01Pb(I_0.99Br_0.01)₃ films. All films' direct optical bandgap energies were determined to be 1.54 eV. The effects of OAI addition on the films' photoluminescence intensity and emitted colors were also investigated. For the fabricated perovskite solar cells (PSCs) without an OAI passivation layer, the corresponding power conversion efficiency (PCE), open-circuit voltage (V_OC), short-circuit current density (J_SC), and fill factor (FF) values were 18.8%, 1.02 V, 24.6 mAcm^-2, and 75%, respectively. When the concentration of OAI reached 2 mg, the maximum obtained values of PCE, V_OC, J_SC, and FF were 20.2%, 1.06 V, 24.2 mAcm^-2, and 79%, respectively. The decreased trap density and increased recombination resistance were responsible for the improvement in solar cell performance.

Bandgap Tuning and Blue-Green Band Emissions of Sol-Gel Synthesized ZnO Films by High Cu Doping

The present research focuses on the preparation of ZnO thin films both undoped and doped with varying Cu concentrations (0.0%, 0.8%, 3.0%, 5.0%, 10.0% and 20.0%) using sol-gel spin coating technique. The optical bandgap (E_g) for undoped films is recorded as 3.239 eV and shows a little increase to 3.248 eV when it is doped with 0.8% Cu concentration whereas further increase of Cu doping concentration, it is decreased from 3.248 eV to 3.107 eV for 20% Cu. The E_U (Urbach Energy) is improved with the enhancement of Cu doping concentration. Ultraviolet (UV) and bluegreen band emissions are noticed from PL (photoluminescence) spectra. The UV peak intensities are diminished with increasing Cu doping concentration while the blue peaks intensities are amplified. These results illustrate that ZnO films doped with Cu meet the requirement for applications in different blue emission devices.

Synthesis and structure of novel Ag2Ga2SiSe6 crystals: promising materials for dynamic holographic image recording

Phase diagrams of the AgGaSe₂–SiSe₂ system were explored by differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis methods for the first time.

Nissen fundoplication, robotic-assisted versus laparoscopic procedure: a comparative study in children

BACKGROUND/PURPOSE

Many reports have addressed the feasibility and safety of robotic-assisted surgery. However, few have compared the use of robots with the standard laparoscopic approach in various procedures. The aim of this study was to compare robotic-assisted Nissen fundoplication (RNF) with laparoscopic Nissen fundoplication (LNF).

METHODS

Children who underwent RNF were compared with those who underwent LNF during the same period at the same institution. Data collected included patient demographics, surgical indications, operative times, intraoperative and postoperative complications and clinical outcomes.

RESULTS

Between January 2005 and July 2008, 25 patients underwent RNF and 25 underwent LNF. Both groups were similar with regard to age, male/female ratio, and body weight. The total operative time was comparable in both groups. There were no deaths, intraoperative complications or untoward events. There were no significant differences in postoperative complication rates, postoperative analgesic requirements or lengths of hospital stay between the groups. Short-term clinical results with respect to gastroesophageal reflux symptoms were comparable in both groups after 14 months of follow-up.

CONCLUSION

RNF is a safe and feasible alternative to LNF. There were no significant differences in outcomes measured between groups. In view of the high cost of robotic devices, no clear benefits of using robotics in Nissen fundoplication were observed.