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Seleniferous red soils cover a large area in the southern part of China. These agricultural soils are enriched in selenium (Se), heavy metals, and rare earth elements and have been cultivated for more than 1000 years for rice production without any consideration of the effects of selenium, heavy metals, and rare earth element bioaccumulation in the food plants produced. To address this knowledge gap, this study focuses on the investigation of Se, heavy metals, and rare earth elements within soils and plants in the region. The rice (Oryza spp.) plants studied were grown in the Gutian (GT), Gechuan (GC), and Pengkou (PK) villages in Lianchen (LC) County, Fujian Province. The surface soils and harvested rice tissues were collected to determine the Se, Cd, Zn, Pb, La, Ce, and Nd concentrations in the soils and plant tissues. Different rice cultivars possessed various potentials for elemental accumulation. Generally, rice plant tissues accumulated certain amounts of these elements; however, the elemental concentrations found in rice grain were within the acceptable ranges stipulated by the National Security Standard of Food. The Hongbaoshi (HBS) Indica red rice produced in the PK village accumulated more selenium, heavy metals, and rare earth elements than those in the plant tissues of the Xinyinzhan (XYZ) and Wushansimiao (WSSM) rice cultivars because HBS had more root hairs and finer root distribution. Thus, in the interest of food safety, increased attention needs to be given to the careful selection of the optimum crop species planted in these types of seleniferous red soils.

This study aims to compare the clay mineralogy and whole-soil major chemistry of elements in late Miocene soil sediments and early Quaternary red paleosols in the Penghu Islands, (Pescadores), Taiwan, and Zhangpu Volcanic Park, Fujian. There were the late Miocene Chu Wan (CWI and CWII), Shiao Men Yu (SMY) and two intergrade red soils, Chu Wan (CW(irs)) and Shiao Men Yu (SMY(irs)), with three distinctive zones of different dominating kaolins in the profiles of the Penghu Islands. A Tong Wei (TW) paleosol of early Quaternary basaltic eruptions in the Penghu Islands was collected. The Anzei (AZ), Si Yu (HY) and Chianmei (CM) paleosols were sampled from the Penghu Islands and Yulinshi (YLS) paleosols near the Zhangpu Volcanic Park for this study. The CW and SMY paleosols erupted in the late Miocene, and the other paleosols erupted on the Penghu Islands. These paleosols were fractionated into clay fractions and subjected to soil physical and chemical analyses. Kaolin minerals were dominant in the CW(irs) and SMY(irs) paleosols. The top layer (layer one) in the CW(irs) was 7 Å-halloysite, and order/disordered kaolinites were present in layers two and three. The CW(irs) and SMY(irs) hexagonal-like, platy kaolinites (0.1–0.2 µm in diameter), spheroidal and hollow 7 Å-halloysite (layer 1) was determined with transmission electron microscopic (TEM) investigations. The early Quaternary red soil of TW consisted of kaolinite, illite, vermiculite and smectite clay assemblages. Late Miocene paleosols were classified as fine, kaolinite, hyperthermic and Typic Rhodic Paleudults, and the early Quaternary red paleosols were classified as fine, mixed, hyperthermic and Typic Rodistalf, respectively. Late Miocene paleosols contained more clays, lower SiO2/Al2O3 and higher chemical index of weathering (CIW) than early Quaternary paleosols. The kaolin, illite, smectite and vermiculite mineralogy, physical and chemical properties of paleosols and landscapes in the Zhangpu YLS, Fujian, were similar to those of late Miocene sediments and early Quaternary red paleosols in the Penghu Islands.

Reversible addition–fragmentation chain transfer (RAFT)-mediated polymerization-induced self-assembly (PISA) is an in situ growth method of growing interest for the preparation of well-defined bloc...

In this paper, a singly-averaged, semi-analytical orbital dynamic model in terms of Milankovitch elements is given for geostationary transfer orbits (GTOs), which includes the Earth's oblateness, luni-solar perturbations, atmospheric drag and solar radiation pressure (SRP). The orbital dynamic model is verified through a numerical simulation compared with the Semi-analytic Tool for End of Life Analysis software (STELA) by CNES. We find that if the area-to-mass ratio of the object is relatively large, the SRP will have a significant impact on the long-term evolution of GTOs. Then, the long-term dynamical evolution and orbital resonances of rocket upper stages in inclined geostationary transfer orbits (IGTOs) are studied. It has been found that the luni-solar secular resonances, which are inclination-dependent-only, play a leading role in the long-term evolution of IGTOs. By comparing and analyzing long-term dynamical evolution of orbits with different initial inclinations, the effects of luni-solar secular resonances are studied in details. Finally, a mitigation method for IGTO objects by utilizing luni-solar secular resonances is proposed, in which the eccentricity growth caused by the resonances is used for an early atmospheric re-entry.

This study aimed to determine the microbial diversity of different soil depths (0-5 and 5-20 cm) in a subtropical orchard during different seasons (i.e., Spring, Summer and Autumn) for enrich the knowledgements on micorbes roles in orchard ecosystem balance. In tracking experiments conducted in an orchard (established in 1996), the phospholipid fatty acid (PLFA) biomarker method was employed to know soil microbial system. Total PLFAs concentration did not vary significantly between soil depths but changed between seasons. It peaked in the summer at 258.97 ± 23.48 μg g-1soil from 0-5 cm and at 270.99 ± 58.94 μg g-1soil from 5-20 cm. A total of 33 microbial fatty acid biomarkers were observed and identified in the sampled soil. Quantities of PLFAs for 29 microbe groups varied significantly between seasons, except for 15:0 iso 3OH, 15:1 iso G, 16:0 2OH, and 17:0 iso 3OH. The bacterial PLFAs and fungal and actinomycotic PLFAs in the orchard soil collected in Summer were significantly higher than in the Spring or Autumn (P< 0.01). The number of soil microorganism species (Richness) and the Simpson and Shannon-Wiener indexes were all the highest in summer. The total PLFAs, bacterial PLFAs, fungal PLFAs, actinomycotic PLFAs, Richness, or the Simpson and Shannon-Wiener indexes were all significantly negatively correlated with soil pH, total carbon (TOC), total nitrogen (TN) and cation-exchange capacity (CEC) (P< 0.05).

In order to provide a novel biomimetic composite substrate for tissue engineering and explore the interaction between cells and this type of material, we developed chitosan/liquid crystal (CS/LC) composite hydrogel with embedded LC phases by composing of cholesterol hydroxypropyl cellulose ester liquid crystalline material and CS. The micromorphology of CS/LC composite hydrogels exhibited ‘islands-sea’ phase separation structures similar to the ‘fluid mosaic model’ of biomembrane. In vitro cell compatibility study suggested that 3T3 is fibroblasts exhibited better initial cell adhesions and higher proliferation rates on the composite hydrogel than on the polystyrene control plate and the pure LC membrane. This novel CS/LC composite hydrogel provides more favorable interface for cell growth and proliferation and may serve as potentially active substrate for engineering interfaces to live cells.

Hafnium dioxide has been recently introduced as a gate dielectric in the field effect transistors. It belongs to a class of high dielectric constant or high-k dielectrics. We briefly discuss the structural and electronic properties of bulk hafnia, and show how oxygen vacancies believed to affect the band alignment across the metal oxide semiconductor (MOS) stack are stabilized in hafnia films next to high work function metals.

Data from towed streamer surveys in shallow water environments are usually contaminated by different orders of sea floor reflections called water-layer-related multiples (WLRMs). The model-based water-layer demultiple (MWD) method effectively removes WLRMs. The initial development of 2D MWD was followed by a 3D implementation to better handle out-of-plane WLRMs. This 3D implementation was further improved by using a selective-input strategy to handle the inconsistency of the high-frequency multiple patterns between adjacent sail lines and shots. Time-variant aperture scheme is proposed based on multiple contribution gathers (MCGs) to include sufficient large apertures, avoid aliasing problems, and compensate for apex shifting. Using narrow azimuth towed streamer (NATS) data from the Hibernia field, we demonstrate the benefit of selective-input MWD with timevariant apertures for attenuating WLRMs in shallow water data.

We reported the synthesis of titanium disulfide (TiS 2 ) whiskers on Ni-coated Si wafer via a simple vapor transport deposition method at 630 °C. To our knowledge, this is the first time to report the synthesis of TiS 2 whiskers with exact stoichiometric composition. By gently controlling the configuration of S and Ti sources and Si substrate during vapor reaction, TiS 2 whiskers could be successfully acquired. TiS 2 whiskers are single crystalline with exact stoichiometric composition. This kind of solid sulfide source method also can be used for synthesis of other transitional metal dichalcogenide whiskers. We believe that the successful growth of TiS 2 whiskers would provide significant theoretical and experimental opportunities for researchers.

ZnSe nanoparticles were synthesized via a simple, effective thermal evaporation method by a vapor phase reaction of Zn and Se powder. Particle characterization was performed by X-ray diffraction (XRD), transmission electron microscopy (TEM). It is found that the higher the growth temperature, the larger the nanoparticles. Obvious blue shift was observed in the photoluminescence (PL) spectra at room temperature with decreasing particle size. Raman spectra of the as-grown ZnSe nanoparticles were compared with that of the bulk ZnSe crystal. Though no obvious peak shift was observed for both the transverse optical (TO) and longitudinal optical (LO) phonon modes within the apparatus spectral resolution, non-symmetrical broadening of the LO phonon mode is obvious, indicating that the phonon lifetime is shorter in ZnSe nanoparticles than in bulk material.

A simple vapor phase growth method was used for large-scale synthesis of high-purity Mn 3 O 4 nanowires on silicon substrates. The microstructure, morphology and chemical composition of as-grown Mn 3 O 4 nanowires were investigated using the X-ray diffraction and electron microscopy methods. The products were composed of pure and single crystalline tetragonal structure Mn 3 O 4 nanowires. The nanowires had an average diameter of ∼200 nm and length of 10 μm. Magnetic measurements showed that Mn 3 O 4 nanowires had a high Curie temperature, T c , around 51 K and a large coercive force of about 5710 Oe.

Aligned TiO2 nanowire arrays were fabricated onto Si wafers by a simple thermal deposition (PVD) method. Scanning electron microscopy and high-resolution transmission electron microscopy observations confirm that the as-prepared TiO2 nanowires are single-crystalline and of high purity. Field emission measurements showed that the TiO2 nanowire arrays could provide stable, high-current electron emission at a low voltage. The emission current monitored over a period of 24 h fluctuated gently but did not show degradation. The cathode-luminescence (CL) images captured by a CCD camera were very bright and their CL intensity was homogeneous. This remarkable performance reveals that TiO2 nanowire arrays are well suited for commercial use in electron devices, particularly flat panel displays.

Selenium dioxide nanowires were fabricated as the co-products of ZnSe nanostructures. The SeO2 nanowires have diameters between 20∼70 nm and lengths up to several hundred micrometers. The morphology and microstructure of the nanowires were analyzed using TEM, and the growth mechanism of the SeO2 nanowires was explained under the framework of a vapor-solid model, in which structure defects may play a very important role in the nanowire growth. The nanostructured SeO2 materials may find application in both catalytic and biological fields.

Silica sheathed titania nanocable arrays were synthesized on Si substrates by using a vapor phase method. The morphology, microstructure, and chemical composition of the nanocables were characterized by using scanning electron microscopy, transmission electron microscopy, and spatial-resolution energy-dispersive X-ray spectroscopy, respectively. Raman spectroscopy combined with the other characterization methods elucidates that the nanocable core is of rutile titania. X-ray photoelectron spectroscopy indicates the existence of Ti−O−Si bonds as well as Ti−O−Ti and Si−O−Si bonds. A possible growth mechanism of the nanocables was also proposed on the basis of thermodynamic and kinetic considerations. The as-grown nanocable arrays may find applications as photocatalysts.

Nanosized manganese oxide particles have been synthesized via vapor phase growth. The diameter of the nanoparticles can be controlled by the growth temperature: the higher the temperature, the larger the diameter of the particle. Magnetization measurements show that the manganese oxide nanoparticles have an obvious ferromagnetic behavior with the Curie temperature around 40 K. The latter is size-dependent, namely: the smaller is the diameter of the particles, the lower is the Curie temperature.

We describe a vapor-phase route to the controllable synthesis of indium oxide micro-and nanopyramids on the silicon wafer via selective epitaxial vapor-solid growth by a methane-assist thermal reduction method. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy revealed that the pyramids were cubic single crystals with a tetragonal symmetry. The size, morphology, and density of pyramids could easily be controlled by tuning reaction parameters. The method has good compatibility with other procedures involved in the microfabrication processes. Laterally grown indium oxide nanorods on the silicon wafer were also prepared via a vapor-liquid-solid mechanism. Those crystalline In2O3 nanorods were about 100 nm in diameter and 1 μm in length. The as-synthesized indium oxide nanopyramids and nanorods could offer novel opportunities for both fundamental research and technological applications.

High-purity ZnO nanowires, which possess branching structures, were prepared by evaporating metal zinc onto thermally oxidized Si wafer. The morphology and microstructure analyses of ZnO crystals were performed by scanning electron microscopy and high-resolution transmission electron microscopy. The nanowires possess hexagonal wurzite structure. The 1-D growth mechanism of ZnO nanowires corresponds to Sears theory. Multiply twinned ZnO fine particles deposited on silica surfaces serve as the growth centers of branching structure. The dendrite ZnO nanowires have potential for building optoelectronic nanodevices with special configurations or as building blocks in the construction of functionalized interfaces.

High-density ZnO nanowires (ZnONWs) were aligned onto Au-catalyzed Si substrate through a simple low-temperature physical vapor deposition method. Scanning electron microscope (SEM) observations, x-ray diffraction (XRD) analysis, and photoluminescence spectra showed that the ZnONWs were single-crystalline, with a hexagonal wurzite structure. All of the results inferred from the SEM observations, the XRD rocking curves, and the Raman spectra for the investigated samples confirm that the ZnONWs are well aligned and c-axis oriented. The Raman spectra also indicated that the ZnONWs on Si substrates are under the biaxial compressive stress. Since it takes the advantage of low-cost, easily controlled deposition spot (due to the selective deposition trait of the Au layer), potential for scale-up production, and ability to integrate with Si substrate, this technique has a potential in future for fabricating the ZnONW array-based optoelectronic devices.

Diluted magnetic semiconductor Zn1−xMnxO nanowires were synthesized via an in situ doping of manganese in ZnO nanowires using vapor phase growth at 500 °C. The maximum content of the manganese in the ZnO is around 13 at. %, approaching the maximum thermal equilibrium limit of Mn solubility in ZnO at the growth temperature. Structure and composition analysis revealed that the manganese was doped into the lattice structure, forming solid solution instead of precipitation. Magnetic property measurements revealed that the as-doped Zn1−xMnxO nanowires exhibit ferromagnetic behavior with Curie temperature around 37 K.

Well-aligned indium oxide pyramids were synthesized on a Ni-coated silicon (100) substrate by a chemical vapor deposition. Scanning electron microscopy and x-ray diffraction investigations show that these pyramids present a tetragonal morphology and single-crystalline cubic bixbyite structure. The size control of the pyramids was achieved by varying the growth temperature. Field-emission characteristics of the as-grown indium oxide pyramids were measured. The field-emission current density of the nanopyramids (average size: ∼180 nm) reached about 1 mA/cm2 at a threshold field of about 6.0 V/μm, which is comparable to that of carbon nanotubes, and can guarantee sufficient luminescence brightness in a flat panel display.

Using density functional theory (DFT) we examine the effect of Al and La incorporation on the electronic properties of the interface in the SiO${}_{2}$/HfO${}_{2}$ high-k gate stacks recently introduced into the advanced modern field effect transistors (FETs). We show that La and Al doping have opposite effects on the band alignment at the SiO${}_{2}$/HfO${}_{2}$ interface: while the Al ions, which substitute preferentially for Si in the SiO${}_{2}$ layer, promote higher effective work function (EWF) values, the substitution of La for Hf decreases EWF. The analysis of the electronic structure of the doped interface suggests a simple relation between the electronegativity of the doping metal, screening properties of the interfacial layer, and the band offset, which allows predicting qualitatively the effect of the high-k gate stack doping with a variety of metals on its EWF.

Continuous scaling in semiconductor technology, associatsed with Moore’s law, brought new materials in every functional element of Si-based metal-oxide-semiconductor (MOS) field effect transistors (FET). In particular, for a gate dielectric instead of traditional SiO2 new HfO2-based oxides with higher dielectric constants are now used. The introduction of these so-called high-k dielectrics opened the possibility of using high mobility semiconductors instead of Si in MOS technology. In this chapter we discuss density functional calculations of high-k oxides hafnia and zironia. After briefly describing theoretical methods used in our calculations we discuss the bulk properties, surfaces and interfaces of hafnia and zirconia relevant to advanced gate stack engineering.

We use a combination of density functional theory and calorimetric measurements to investigate the monoclinic to tetragonal transition in hafnia and zirconia. We measure the transition enthalpies to be $8.4\ifmmode\pm\else\textpm\fi{}0.7\text{ }\text{kJ}/\text{mol}$ in hafnia and, as previously reported, $5.272\ifmmode\pm\else\textpm\fi{}0.544\text{ }\text{kJ}/\text{mol}$ in zirconia. Calculated values are 10.21 and 7.50 kJ/mol for hafnia and zirconia, respectively. We formulate a theoretical model of the phase transition consistent with the martnesitic character of the transformations. The transition barriers of 20.3 and 16.3 kJ/mol are estimated for hafnia and zirconia, respectively. We report the phonon spectra of monoclinic and tetragonal phases of both oxides and identify the Raman and IR active modes. The theoretical results compare well with available experiments. We present a comprehensive theoretical comparison of thermodynamic properties of zirconia and hafnia including the temperature dependence of specific heat.

Hafnium dioxide that belongs to a class of metal oxides with a high dielectric constant or high-k dielectrics has been recently introduced as a gate dielectric in field effect transistors. We report a theoretical study of structural and electronic properties of hafnia surface, and the electronic structure and band alignment at hafnia interfaces with metals, oxides and semiconductors that are crucial in gate stack engineering.

We present a joint experimental and theoretical study of ultrathin hafnia films grown on Si (001) by atomic layer deposition for applications as a gate dielectric of a field-effect transistor. The structural analysis by means of high-resolution transmission electron microscopy, electron diffraction, and x-ray diffractometry indicates films with thickness of 4 nm or less to be polycrystalline, predominantly monoclinic and textured, with the texture axis being the normal to the $(21\overline{1})$, $(11\overline{2})$, and their equivalent planes. Films with thickness around 10 nm consist of a mixture of monoclinic and tetragonal phases more or less randomly oriented. Films thicker than 25 nm are purely monoclinic with $(\overline{1}11)$ and (111) textures. Using density-functional theory we investigate surface energies of monoclinic and tetragonal hafnia films in search for thermodynamic means of controlling the film microstructure. We report the atomic and electronic structures of these films including the surface energy, work function, and electron affinity.

Density functional theory has proved to be a useful tool in device engineering, particularly at nanoscale and when novel materials are involved. In this chapter we briefly introduce the theoretical background necessary for understanding the modern theory of solid state and review recent theoretical results in the area of advanced gate stack materials engineering.

We investigate theoretically amorphous hafnia using the first principles melt and quench method. We identify two types of amorphous structures of hafnia. Type I and type II are related to tetragonal and monoclinic hafnia, respectively. We find type II structure to show stronger disorder than type I. Using the phonon density of states, we calculate the specific heat capacity for type II amorphous hafnia. Using the nudged elastic band method, we show that the averaged transition barrier between the type II amorphous hafnia and monoclinic phase is approximately 0.09 eV/HfO2. The crystallization temperature is estimated to be 421 K. The calculations suggest an explanation for the low thermal stability of amorphous hafnia.

Polycrystalline GaN thin films have been deposited epitaxially on a ZnO-buffered (111)-oriented Si substrate by molecular beam epitaxy. The microstructural and compositional characteristics of the films were studied by analytical transmission electron microscopy (TEM). A SiO2 amorphous layer about 3.5 nm in thickness between the Si/ZnO interface has been identified by means of spatially resolved electron energy loss spectroscopy. Cross-sectional and plan-view TEM investigations reveal (GaN/ZnO/SiO2/Si) layers exhibiting definite a crystallographic relationship: [111](Si)//[111](ZnO)//[0001](GaN) along the epitaxy direction. GaN films are polycrystalline with nanoscale grains (similar to100 nm in size) grown along [0001] direction with about 20degrees between the (1 (1) over bar 00) planes of adjacent grains. A three-dimensional growth mode for the buffer layer and the film is proposed to explain the formation of the as-grown polycrystalline GaN films and the functionality of the buffer layer. (C) 2004 Elsevier Ltd. All rights reserved.

We report a calibrated equipment for return loss (RL) of fiber optic passive components, the expanded uncertainty for this equipment are 0.80dB(0--60)dB, 1.60dB(-60- -70)dB with 1300 nm and 1550 nm wavelength, RL measurement repeatability to 0.25dB(--60)dB, 0.50dB(-60--70)dB, and stability to 0.20dB(0- -60)dB, 0.40dB(-60--70)dB are obtained by experiments.