Search

The effects of pretreatment methods (DR, R, ROR) on the microstructure of Co/SiO2 catalysts and the activity for Fischer-Tropsch synthesis (FTS) were investigated. The pretreated catalysts were characterized by TEM, HRTEM, XRD, XPS, H2-TPD, TG and TPR. The results showed that after the pretreatments, specific morphological of the Co species changed, forming new Co active surface species. The Co particles redispersed and the Co species was facile to be re-reduced. The Co/SiO2 catalysts pretreated by different method showed different catalytic performance. The catalyst treated by the reduction-passivation had higher activity and \begin{document}${\rm{C}}_{5}^ {+} $\end{document} selectivity for FTS.

Additional file 1.

Debris flows often pose great threats to people���s lives and property in mountainous regions. For example on August 8, 2010, a debris flow with a volume of 220��104 m3 occurred in ZhouQu county, Gansu province, China. The debris flow resulted in not only significant loss of farmlands, but also in 1,248 deaths and 496 people missing. The construction of check dams in debris- flow valleys is a useful way to mitigate deaths and damages. Herein, we investigate scour downstream from check dam spillway structures. We propose that the main parameters which determine scour depth of a scour hole downstream from check dams, include flow density, flow depth, flow discharge per unit width, and acceleration due to gravity. Physical experiments were also carried out to investigate debris flow movement and scour characteristics. In addition, a theoretical expression was deduced to predict the maximum scour depth downstream from check dams. There was a good correlation between experimental data and results predicted from theory. The results obtained in this paper can provide constraints for the design of check dams in mountainous areas.

We report a new and simple approach to prepare a class of silica-reinforced liposomes with hybrid core-shell nanostructures. The amphiphilic natural structure of lipids was exploited to sequester hydrophobic molecules, namely precursor TEOS and pyrene, in the hydrophobic midplane of liposomal bilayer assemblies in the aqueous phase. Subsequent interfacial hydrolysis of TEOS at the bilayer/water interface and ensuing condensation within the hydrophobic interstices of the lipid bilayer drives silica formation in situ, producing a novel class of silica-lipid hybrid liposils. Structural characterization by scanning- and transmission electron microscopy confirm that the liposils so generated preserve closed topologies and size-monodipersity of the parent lecithin liposomes, and DSC-TGA and XRD measurements provide evidence for the silica coating. Monitoring fluorescence measurements using embedded pyrene yield detailed information on microenvironment changes, which occur during sol-gel process and shed light on the structural evolution during silica formation. We envisage that liposils formed by this simple, new approach, exploiting the hydrophobic core of the lipid bilayer to spatially localize silica-forming precursors enables preparation of stable liposils exhibiting capacity for cargo encapsulation, bicompatibility, and fluorescence monitoring, more generally opening a window for construction of stable, functional hybrid materials.

Various morphology ZnO submicrorods and microrods have been fabricated onto glass substrates through chemical solution growth by the source of zinc acetate (Zn(CH3COO)2.2H2O) and hexamethylene tetraamine ((CH2)6N4). We discuss the influence of PH and the concentration of the solution on the shapes of the as-synthesized ZnO samples. And analyse the growth mechanism. The regular hexagonal ZnO rods align has been made by control of a certain concentration and proper PH. The hexagonal ZnO columns mainly grew in the [002] direction. X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) are used to characterize the structure, the morphology and optical property of the samples. The photoluminescence spectrum of hexagonal ZnO columns shows that there are a broad strong red band (650nm) and a broad band in short wavelength which are two overlapped emission bands with the peaks at about 380nm and 430nm.The UV emission (~387nm) comes from recombination of free excitons. The blue emission with peak at 430nm is assigned for the recombination from an electron at interstitial Zn to a hole in VB. The red emission at 650nm is ascribed to the recombination from an electron at Vo2+ to a hole in VB.

Hexagonal ZnO microrods and sub-microrods have been prepared through thermal decomposition of an equimolar (0.1 M) aqueous solution of Zn(NO3)2.4H2O and (CH2)6N4 at 90 degrees C for different times (10–46 h). The microrods were transformed into hollow hexagonal ZnO microtubes when the growth time reached 46 h. The Raman spectra and the photoluminescent (PL) spectra were measured. The PL spectra of microrods consist of two strong narrow near-UV bands at 380 nm and 400 nm assigned to free exciton emission and exciton–exciton collision, respectively. The PL spectrum of ZnO microtubes show only one peak in the near-UV region with peak located at 380 nm with FWHM of about 20 nm assigned to free exciton emission. When the growth time increased, the peak intensity of near-UV band decreased.

Based on theories of protective forests and landscape ecology, the reasonableness of structures and patterns of shelterbelt system at Beizang Town, Daxing County, Beijing were analyzed and assessed from the two scales of forest belts and networks, by integrating uses of field investigation, GIS and RS techniques. Results showed that the existent main belt (3–12 m in width) was too narrow, while the assistant belt (3–27.1 m in width) was too wide; the species composition of the existent shelterbelts was single, and the structures and patterns of the shelterbelt system were unreasonable. It is suggested that the structure of the main and the assistant belts should be changed, such as increasing the width of main belts, decreasing the width of assistant belt, and planting more mixed species, and the pattern with arbores in the middle and shrubs in the sides of belts could be taken into account. For the landscape structure of forest network after regenerating or reconstruction, the grid number of closed network should be 13 per km2 and the minimum number of belts should be 34 per km2. This study also testified that integrating GIS and remote technique with landscape ecology could provide an effective method for reasonable reconstruction of the structures and patterns of shelterbelts system.

The stomachs of the yellow-billed grosbeaks were examined by means of light microscopy. The mucous membrane of the proventriculus presented many folds and sulci. The sulci were lined by simple columnar cells with basal nuclei and clear acidophilic cytoplasm. The proventriculus glands were constituted by many round or elliptical glandular lobules. The sulci and the collecting duct of compound tubular glands showed an intense positive reaction in PAS and AB stain. The gizzard was characterized by an internal abrasion-resistant lining cuticle and a thick muscular layer. The cuticle, gizzard glands and muscular layer in two sides were thicker than those in the cranial and caudal. Los estómagos del Pepitero de cola negra fueron examinados mediante microscopía óptica. La membrana mucosa del proventrículo presentó muchos pliegues y surcos. Los surcos estaban revestidos por células columnares simples con núcleos basales y un citoplasma claro acidófilo. Las glándulas proventriculares estaban constituidos por abundantes lóbulos glandulares redondos o elípticos. Los surcos y conductos colectores de las glándulas tubulares compuestas mostraron una reacción positiva e intensa a las tinciones de PAS y AB. La molleja estomacal se caracterizó por una cutícula de revestimiento resistente a la abrasión interna y una capa muscular gruesa. La cutícula, glándulas de la molleja y capa muscular en ambos lados eran más gruesas que en la craneal y caudal.