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The fossiliferous lower Cambrian (Series 2) successions along the north coast of Kangaroo Island, South Australia—known collectively as the Kangaroo Island Group—can be divided into two main areas: a western succession located between Snelling Beach and Smith Bay, which comprises the Mt McDonnell Formation (base), Stokes Bay Sandstone and Smith Bay Shale; and an eastern succession that extends from Emu Bay to Point Marsden, represented by exposures of the White Point Conglomerate (base), Marsden Sandstone, Emu Bay Shale and Boxing Bay Formation (top), with an overlap in the Cape d'Estaing/Emu Bay area. Some previous interpretations of the Kangaroo Island Group stratigraphy suggest that the western succession stratigraphically underlies the eastern succession. Most of the previously reported and described Cambrian fossils come from the eastern succession, especially the internationally significant Emu Bay Shale Konservat-Lagerstätte. Here we report the trilobites Redlichia takooensis and Balcoracania dailyi from the Smith Bay Shale near Freestone Creek, indicating that the eastern and western successions are at least partly contemporaneous. The present investigation indicates that the Smith Bay Shale of the western succession can be correlated with the stratigraphic interval represented by the Marsden Sandstone and the overlying Emu Bay Shale of the eastern succession. The Kangaroo Island Group was deposited as part of a fan delta system with the eastern succession representing the proximal part, and the western succession representing the distal part of the fan delta. The lack of substantial conglomerate units within the Kangaroo Island Group to the west of Cape d'Estaing suggests that the tectonic uplift that led to the deposition of the White Point Conglomerate was concentrated in the area immediately to the north of Emu Bay. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To analyze the correlation of serum placental growth factor (PLGF), pregnancy-associated plasma protein-A (PAPP-A) and disease severity in patients with hypertensive disorders in pregnancy (HDP). PATIENTS AND METHODS: Altogether 88 pregnant women with hypertensive disorder who underwent prenatal examination and delivery in our hospital from March 2017 to February 2019 were selected and included as the research group (n=88), and 62 healthy pregnant women who underwent prenatal examination during the same period were included as the normal control group (n=62). Enzyme-linked immunosorbent assay (ELISA) was used to detect the expression levels of PAPP-A and PLGF in the serum of the two groups. The correlation of the expression levels of PAPP-A and PLGF with the severity of HDP was analyzed. The occurrence of adverse pregnancy outcomes in the two groups was compared, and the relationship of the expression levels of PAPP-A and PLGF with adverse pregnancy outcomes was compared. RESULTS: PAPP-A expression level in serum of pregnant women in the research group was significantly higher than that in the control group, while PLGF expression level was significantly lower than that in the control group (p<0.001). PAPP-A expression level was positively correlated with HDF severity (r=0.753, p<0.001), while PLGF expression level was negatively correlated with HDP severity (r=-0.929, p<0.001). The incidence of adverse pregnancy outcomes in the research group was significantly higher than that in the control group (p<0.05). The serum PAPP-A level of patients in the group with adverse pregnancy outcomes was significantly higher than that in the group without adverse pregnancy outcomes, while PLGF level was significantly lower than that in the group without adverse pregnancy outcomes (p<0.001). CONCLUSIONS: In conclusion, the expression levels of PAPP-A and PLGF in serum were closely related to the severity of HDP and could be used as indicators for disease monitoring. [ABSTRACT FROM AUTHOR]

Bi3+-Ln3+ (Ln = Dy, Er, Ho, Eu, and Sm) co-doped YVO4 phosphors are proposed as UV-absorbing luminescent converter candidate to enhance the power conversion efficiency and photochemical stability of dye-sensitized solar cells (DSSCs). The phosphors can efficiently convert UV photons in a broad range from 250 to 400 nm into visible emissions, which can be absorbed by DSSCs. Efficient broadband down-conversion UV light into near-infrared emission around 1000 nm was achieved in the YVO4:Bi3+,Yb3+ phosphors. The energy transfer from V5+-Bi3+ charge-transfer state to Yb3+ was shown to be a cooperative down-conversion type by the luminescence spectra, energy transfer efficiency, and luminescence decay curves. The YVO4:Bi3+,Yb3+ phosphors are promising for boosting the efficiency of crystalline silicon solar cells by down-converting the UV part of the solar spectrum to near-infrared photons with a twofold increase in the photon number. This research may open up promising new perspectives for designing novel luminescent materials for photovoltaic cells with high efficiency. [ABSTRACT FROM AUTHOR]

Using terahertz time-domain spectroscopy, we measured the frequency dependent complex dielectric response and conductivity of n-type single-crystal ZnO epilayers with different carrier concentrations over the frequency range from 0.1 to 3.0 THz. The measured complex dielectric response and conductivity are analyzed using Drude model. [ABSTRACT FROM AUTHOR]

We investigate the photoconductivity properties of ZnO thin films prepared by pulsed laser deposition with and without metals (Au or Pt) on the surface. The covering of nanostructured metals can largely enhance the photocurrent. Meanwhile, the dark currents have been increased significantly due to the increase in carrier concentration and mobility near the surface of ZnO thin film. Although plasmonic effect was observed by the photoluminescence enhancement, the main mechanism of the increase in the dark current and photoresponsivity for ZnO photoconductors has been interpreted by surface states, interface states, and persistent photoconductivity. [ABSTRACT FROM AUTHOR]

ZnO nanotubes were fabricated by vapor-phase transport using the mixture of ZnO and graphite powders in air. A self-catalyzed growth mechanism was proposed based on microstructure analysis by scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. Raman scattering, integrated photoluminescence, and time-resolved photoluminescence were employed to explore the optical properties and the dynamic process. Combing with crystal structure and the spectral characteristics of the ZnO nanotubes, the charge carrier transport process was discussed. [ABSTRACT FROM AUTHOR]

Surface defect passivation for ZnO nanocombs (NCBs), random nanowires (RNWs), and aligned nanowires (ANWs) was performed through a metal plasma immersion ion implantation with low bias voltages ranging from 0 to 10 kV, where Ni was used as the modification ion. The depth of surface-originated green band (GB) emission is thus probed, revealing the surface origin of the GB. It is also found that the GB is closely related to oxygen gas content during growth of the nanostructures. The GB origin of NCBs and RNWs grown with higher oxygen content is shallower (∼0.5 nm), which can be completely quenched with no bias applied. However, the GB origin of ANWs grown at lower oxygen content is much deeper (∼7 nm) with a complete quenching bias of 10 kV. Quenching of the GB can be attributed to passivation of the surface hole or electron trapping sites (oxygen vacancies) by Ni ions. [ABSTRACT FROM AUTHOR]

Postgrowth annealing was carried out on ZnO thin films grown by metal-organic chemical-vapor deposition. It was found from the scanning electron microscopy and atomic force microscopy measurements that the morphology of the thin films changed drastically after annealing. The as-grown thin films consist of fine nanoscale-sized sheets with random orientation. Upon annealing at 800 °C, the ZnO nanosheets changed to three-dimensional nanoneedles. The different types of the mass transport mechanisms are discussed and correlated with the experimental results. A coarsening kinetics developed by Lifshitz and Slyozov [J. Phys. Chem. Solids 19, 35 (1961)] and Wagner [Z. Elektrochem. 65, 581 (1961)] was used to estimate the activation energy of the coarsening process. The activation energy of the Ostwald ripening in ZnO films was estimated in the first attempt, and the value is at around 1.33 eV. Hall effect and photoluminescence measurements were carried out to investigate the effect of coarsening on electrical and optical properties of the ZnO thin films. [ABSTRACT FROM AUTHOR]

The band structures of wurtzite ZnO are calculated by the empirical pseudopotential method (EPM). The eight parameters of the Zn and O atomic pseudopotential form factors are obtained with the formula of Schluter et al.[Phys. Rev. B 12, 4200 (1975)]. The band parameters are extracted by using a k·p Hamiltonian to fit the EPM results. The calculated band-edge energies (Eg, EA, EB, and EC) at the Γ point are in good agreement with the experimental results. Based on the band parameters obtained, valence subbands of wurtzite ZnO/MgxZn1-xO tensile-strained quantum wells with different well widths and Mg compositions are calculated by the six-band k·p method. [ABSTRACT FROM AUTHOR]

Based on vapor-phase transport method, manganese-doped zinc oxide (ZnO:Mn) tetropod whiskers were fabricated. The pods of the ZnO:Mn whiskers show hexagonal hollow shape with multitips at the front. X-ray diffraction and high-resolution transmission electron microscopy demonstrate that the tube pods and the tips are composed of wurtzite ZnO growing along [0001] direction. The generation of the luminescent center in ZnO whiskers and electron transport between the ground state and the excitation states of Mn2+ are analyzed by Raman-scattering, photoluminescence, and photoluminescent excitation measurements. [ABSTRACT FROM AUTHOR]

The optical band gap of ZnO thin films deposited on fused quartz by metal-organic chemical-vapor deposition was studied. The optical band gap of as-grown ZnO blueshifted from 3.13 to 4.06 eV as the growth temperature decreased from 500 to 200 °C. After annealing, the optical band gap shifted back to the single-crystal value. All the ZnO thin films studied show strong band-edge photoluminescence. X-ray diffraction measurements showed that samples deposited at low temperatures (<450 °C) consisted of amorphous and crystalline phases. The redshift of the optical band gap back to the original position after annealing was strong evidence that the blueshift was due to an amorphous phase. The unshifted photoluminescence spectra indicated that the luminescence was due to the crystalline phase of ZnO, which was in the form of nanocrystals embedded in the amorphous phase. [ABSTRACT FROM AUTHOR]

The electro-optical and response properties of a nematic liquid crystal cell driven by double-side fringe-field switching [ C. Y. Xiang, X. W. Sun, and X. J. Yin, Appl. Phys. Lett. 83, 5154 (2003) ] have been studied. The transmission-voltage curve of the double-side fringe-field cell can be modeled by the change of the maximum twist angle. It is shown that the liquid crystal layer is linearly twisted before the transmission reaches the maximum. The threshold voltage of double-side fringe-field switching is the same as that of single-side fringe-field switching. The turn-on and turn-off response times, showing four time improvement over the single-side fringe-field switching, have been derived. The experimental turn-off times of the double-sides fringe-field switching and single-side fringe-field switching cell match with the theoretical prediction. The experimental turn-on time of the double-side fringe-field switching cell shows four times improvement over the single-side fringe-field one as predicted by the theoretical analysis. [ABSTRACT FROM AUTHOR]

Nanostructural zinc oxide fibers have been fabricated by a simple vapor transport method of heating the mixture of zinc oxide, gallium oxide, and carbon powders in air. The zinc oxide nanofibers showed cauliflower-like, disordered, vertically and horizontally aligned morphologies in different temperature regions. The aligned nanofibers were composed of hexagonal zinc oxide with good crystallinity. Gallium was doped into zinc oxide with a concentration of 0.73 at. %. The growth process and the characteristics can be interpreted by a vapor-liquid-solid mechanism. The field emission of the vertically aligned zinc oxide fiber array showed a low field emission threshold, high current density, rapid surge, and high field enhancement factor. The threshold electric field is about 2.4 V/μm at a current density of 0.1 μA/cm[sup -2]. The field enhancement factor was 2991. The emission current density and the electric field followed the Fowler–Nordheim relationship. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

An approach improving diamond–metal adhesion has been developed based on modeling predictions and experimental verifications on the interfacial stresses modified by catalytic reaction. It is found that N-plasma irradiating onto Ti and tungsten-carbide substrates generates tensile surface stresses while C-plasma irradiation creates strongly compressive stress at the surfaces, both of which deteriorate the diamond–metal adhesion. It is also found that surface oxidation prevents diamond nucleation. Therefore, we applied a graded TiCN interlayer with carefully adjusting the ratio of C and N in the gas mixture to neutralize the interfacial stress and, hence, we have improved the diamond–metal adhesion substantially. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]