Investigation on the Influence of Synovial Fluid and Vitreous Humour on Avulsion Wounds Healing in Rabbits.

In the present study, we investigated the efficacy of vitreous humour and synovial fluid on avulsion wound healing in a rabbit's model. The vitreous humour is a fluid that resembles gel consisting of approximately 98-99% water, little hyaluronic acid, glucose, collagen, anions, cations and ions. It is in the posterior eye chamber for the comparison with synovial fluid that consisted of hyaluronin, lubricin, proteinase, prostaglandins and collagenase. In this study, both synovial fluid and vitreous humour were collected from rabbits by aspiration of vitreous humour from the eye (postmortem) and arthrocentesis procedure was applied for collection of synovial fluid. Twelve adult rabbits were used in this study, they divided into three groups each group consisted of four animals wounded experimentally (an avulsion wound). Our results showed the influence of vitreous humour (group B) on healing of the wound is better than the synovial fluid (group C) in the clinical evaluation of shrinkage of the wound. The histo-pathologically changes also revealed that in the vitreous humour treated group (group B), the wound healing process proceeded better than other groups (control and synovial fluid groups). In conclusion, the histopathological and clinical observations demonstrated that application of vitreous humour on wound might be pivotal in improving the healing of avulsion wounds and establish a new tissue in rabbits.

Microelectrical characterizations of junctions in solar cell devices by scanning Kelvin probe force microscopy.

Scanning Kelvin probe force microscopy was applied to the microelectrical characterizations of junctions in solar cell devices. Surface Fermi-level pinning effects on the surface potential measurement were avoided by applying a bias voltage (V(b)) to the device and taking the V(b)-induced potential and electric field changes. Two characterizations are presented: the first is a direct measurement of Bi-induced junction shift in GaInNAs(Bi) cells; the second is a junction-uniformity measurement in a-Si:H devices. In the first characterization, using Bi as a surfactant during the molecular beam epitaxy growth of GaInNAs(Bi) makes the epitaxial layer smoother. However, the electrical potential measurement exhibits a clear Bi-induced junction shift to the back side of the absorber layer, which results in significant device degradation. In the second characterization, the potential measurement reveals highly non-uniform electric field distributions across the n-i-p junction of a-Si:H devices; the electric field concentrates much more at both n/i and i/p interfaces than in the middle of the i-layer. This non-uniform electric field is due possibly to high defect concentrations at the interfaces. The potential measurements further showed a significant improvement in the electric field uniformity by depositing buffer layers at the interfaces, and this indeed improved the device performance.

Possible approach to overcome the doping asymmetry in wideband gap semiconductors.

The asymmetry doping problem has severely hindered the potential applications of many wideband gap (WBG) materials. Here, we propose a possible approach to overcome this long-standing doping asymmetry problem for WBG semiconductors. Our approach is based on the reduction of the ionization energies of dopants through introduction and effective doping of mutually passivated impurity bands, which can be realized by doping the host with passive donor-acceptor complexes or isovalent impurities. Our density-functional theory calculations demonstrate that this approach provides excellent explanations for the n-type doping of diamond and p-type doping of ZnO, which could not be understood by previous theories. In principle, this approach can be applied to any WBG semiconductors and therefore will open a broad vista for the application of WBG materials.

Electrically benign behavior of grain boundaries in polycrystalline CuInSe2 films.

The classic grain-boundary (GB) model concludes that GBs in polycrystalline semiconductors create deep levels that are extremely harmful to optoelectronic applications. However, our first-principles density-functional theory calculations reveal that, surprisingly, GBs in CuInSe2 (CIS) do not follow the classic GB model: GBs in CIS do not create deep levels due to the large atomic relaxation in GB regions. Thus, unlike the classic GB model, GBs in CIS are electrically benign, which explains the long-standing puzzling fact that polycrystalline CIS solar cells with remarkable efficiency can be achieved without deliberate GB passivation. This benign electrical character of GBs in CIS is confirmed by our scanning Kelvin probe microscopy measurements on Cu(In,Ga)Se2 chalcopyrite films.

Grain-boundary physics in polycrystalline CuInSe2 revisited: experiment and theory.

Current studies have attributed the remarkable performance of polycrystalline CuInSe2 (CIS) to anomalous grain-boundary (GB) physics in CIS. The recent theory predicts that GBs in CIS are hole barriers, which prevent GB electrons from recombining. We examine the atomic structure and chemical composition of (112) GBs in Cu(In,Ga)Se2 (CIGS) using high-resolution Z-contrast imaging and nanoprobe x-ray energy-dispersive spectroscopy. We show that the theoretically predicted Cu-vacancy rows are not observed in (112) GBs in CIGS. Our first-principles modeling further reveals that the (112) GBs in CIS do not act as hole barriers. Our results suggest that the superior performance of polycrystalline CIS should not be explained solely by the GB behaviors.