Leaf stable carbon isotope composition in Picea schrenkiana var. tianschanica in relation to leaf physiological and morphological characteristics along an altitudinal gradient

To understand the effects of leaf physiological and morphological characteristics on δ13C of alpine trees, we examined leaf δ13C value, LA, SD, LNC, LPC, LKC, Chla+b, LDMC, LMA and Narea in one-year-old needles of Picea schrenkiana var. tianschanica at ten points along an altitudinal gradient from 1420 m to 2300 m a.s.l. on the northern slopes of the Tianshan Mountains in northwest China. Our results indicated that all the leaf traits differed significantly among sampling sites along the altitudinal gradient(P<0.001). LA, SD, LPC, LKC increased linearly with increasing elevation, whereas leaf δ13C, LNC, Chla+b, LDMC, LMA and Narea varied non-linearly with changes in altitude. Stepwise multiple regression analyses showed that four controlled physiological and morphological characteristics influenced the variation of δ13C. Among these four controlled factors, LKC was the most profound physiological factor that affected δ13C values, LA was the secondary morphological factor, SD was the third morphological factor, LNC was the last physiological factor. This suggested that leaf δ13C was directly controlled by physiological and morphological adjustments with changing environmental conditions due to the elevation.

Microstructure Morphologies of Asphalt Binders using Atomic Force Microscopy

We investigated microstructure morphologies of three asphalts（SK, Karamay, and Esso） used in China using atomic force microscopy（AFM）. The topography and phase contrast images were obtained. Topographic profile and three dimensional images were described. Roughnesses of microstructure were calculated. And the chemical compositions of asphalt were tested to explain the microstructural mechanism of the asphalt. The results show that the topography and phase image in atomic force microscopy are appropriate to evaluate the microstructure of the asphalt binder. There are significant differences in microstructural morphologies including bee-like structure, topographic profile, 3D image, and roughness for three asphalts in this study. There are three different phases in microstructure of asphalt binder. The oil source and chemical composition of asphalt, especially asphaltenes content have a great influence on the microstructure.

Preparation and Characterization of Urea-formaldehyde Resin/reactive Montmorillonite Composites

The urea-formaldehyde resin/reactive montmorillonite composites were prepared by in situ polymerization. The reactive montmorillonite was prepared firstly by being ion exchanged with organic molecules and secondly by being grafted with silane coupling agent, which could be demonstrated by X-ray diffraction（XRD） and thermogravimetric analysis（TGA）. Scanning electron microscopy（SEM） revealed that the morphology of the urea-formaldehyde resin/reactive montmorillonite composites were ellipsoid or columnar particles. Energy dispersive spectrometry（EDS） confirmed that the reactive montmorillonite was encapsulated by urea-formaldehyde resin. Differential scanning calorimetry（DSC） indicated that curing process of the ureaformaldehyde resin/reactive montmorillonite composites consumed more energy than pure urea-formaldehyde resin. Thermogravimetric analysis（TGA） showed that the thermal stability of the urea-formaldehyde resin/reactive montmorillonite composites improved compared to pure urea-formaldehyde resin. Furthermore, the reactive montmorillonites reduced the formaldehyde emission of the composites and increased the water resistance. Finally, the mechanism to prepare the urea-formaldehyde resin/reactive montmorillonite composites was proposed.

Preparation and Characterization of Multi Shape ZnO/PVDF Composite Materials

Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Fourier transform infrared spectroscopy（FT-IR）, thermal gravimetry（TG）, and X-ray diffraction（XRD） were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.

Surface Functionalized Carbon Nanofibers and Their Effect on the Dispersion and Tribological Property of Epoxy Nanocomposites

Surface functionalization of carbon nanofibers（CNFs） was carried out, i e, CNFs were firstly oxidized and then the surface was silanized by 3-Aminopropyltriethoxysilane（APTES） via an assembly method. A new kind of high wear resistance s-CNFs/epoxy composite was fabricated by in-situ reaction. FTIR spectroscopy was used to detect the changes of the functional groups produced by silane on the surface of CNFs. The tribological properties and microstructures of modified and unmodified CNFs/epoxy composites were studied, respectively. The expremental results indicate that APTES is covalently linked to the surface of CNFs successfully and improves the dispersion of CNF in epoxy matrix. The friction coefficients and the wear rates of s-CNFs/epoxy composites are evidently lower than those of u-CNFs/epoxy composites under the same loads. Investigations also indicate that abrasive wear is the main wear mechanism for u-CNFs/epoxy composite, with slight adhesive wear for s-CNFs/epoxy composite under the same sliding wear condition.

Mechanical Performances and Morphology of LDPE/UHMWPE Single-Polymer Composites Produced by Extrusion-Calendering Method

Extrusion-calendering method was developed to prepare single-polymer composites（SPCs） of ultrahigh molecular weight polyethylene（ UHMWPE） fabric reinforcing low density polyethylene（LDPE）.Differential scanning calorimeter（DSC） experiments were executed to determine the setup of extrusion temperature.Effects of the die temperature on the tensile and interfacial performances of SPCs were studied through the tensile and T-peel tests,respectively. The results showed that both tensile strength and modulus increased initially and decreased afterwards as the temperature increased. The peak values of tensile strength and modulus of PE SPCs,which are 10. 8 and 3. 5 times as high as those of the unreinforced LDPE respectively,were obtained at 150 ℃. Higher temperatures also give a positive effect on peel strength. Scanning electron microscopy（ SEM） and camera were also used to observe the morphology of the SPCs samples.

Size and elemental composition of dry-deposited particles during a severe dust storm at a coastal site of Eastern China

Dry-deposited particles were collected during the passage of an extremely strong dust storm in March, 2010 at a coastal site in Qingdao（36.15°N, 120.49°E）, a city located in Eastern China. The size, morphology, and elemental composition of the particles were quantified with a scanning electron microscope equipped with an energy dispersive X-ray instrument（SEM–EDX）. The particles appeared in various shapes, and their size mainly varied from 0.4to 10 μm, with the mean diameters of 0.5, 1.5, and 1.0 μm before, during, and after the dust storm, respectively. The critical size of the mineral particles settling on the surface in the current case was about 0.3–0.4 μm before the dust storm and about 0.5–0.7 μm during the dust storm. Particles that appeared in high concentration but were smaller than the critical size deposited onto the surface at a small number flux. The elements Al, Si and Mg were frequently detected in all samples, indicating the dominance of mineral particles. The frequency of Al in particles collected before the dust storm was significantly lower than for those collected during and after the dust storm. The frequencies of Cl and Fe did not show obvious changes, while those of S, K and Ca decreased after the dust arrival. These results indicate that the dust particles deposited onto the surface were less influenced by anthropogenic pollutants in terms of particle number.

Effect of lubricant sulfur on the morphology and elemental composition of diesel exhaust particles

This work investigates the effects of lubricant sulfur contents on the morphology,nanostructure,size distribution and elemental composition of diesel exhaust particle on a light-duty diesel engine. Three kinds of lubricant（LS-oil,MS-oil and HS-oil,all of which have different sulfur contents：0.182%,0.583% and 1.06%,respectively）were used in this study. The morphologies and nanostructures of exhaust particles were analyzed using high-resolution transmission electron microscopy（TEM）. Size distributions of primary particles were determined through advanced image-processing software. Elemental compositions of exhaust particles were obtained through X-ray energy dispersive spectroscopy（EDS）. Results show that as lubricant sulfur contents increase,the macroscopic structure of diesel exhaust particles turn from chain-like to a more complex agglomerate. The inner cores of the core-shell structure belonging to these primary particles change little; the shell thickness decreases,and the spacing of carbon layer gradually descends,and amorphous materials that attached onto outer carbon layer of primary particles increase. Size distributions of primary particles present a unimodal and normal distribution,and higher sulfur contents lead to larger size primary particles. The sulfur content in lubricants directly affects the chemical composition in the particles. The content of C（carbon）decreases as sulfur increases in the lubricants,while the contents of O（oxygen）,S（sulfur）and trace elements（including S,Si（silicon）,Fe（ferrum）,P（phosphorus）,Ca（calcium）,Zn（zinc）,Mg（magnesium）,Cl（chlorine）and Ni（nickel））all increase in particles.

Preparation and characterization of urea-formaldehyde resin]reactive kaolinite composites

Novel urea-formaldehyde resin/reactive kaolinite composites containing 20-40wt%; kaolinite were prepared by in situ polymerization. The kaolinite was modified with tetraethoxysilane and a silane coupling agent to introduce reactive groups. Fourier-transform infrared spectroscopy and X-ray diffraction confirmed preparation of the urea-formaldehyde resin/reactive kaolinite composites. The composite morphology was investigated using scanning electron microscopy; the composites consisted of uni- form spherical particles. The surface chemical components of the composites were determined using energy-dispersive X-ray spectroscopy. The spectra showed that the reactive kaolinite was encapsulated by the urea-formaldehyde resin. The thermal properties of the composites were examined using dif- ferential scanning calorimetry and thermogravimetric analysis. The results showed that their thermal stability was much better than that of pure urea-formaldehyde resin, Reactive kaolinite addition greatly decreased formaldehyde emissions and improved the water resistance of the composites. A mechanism for urea-formaldehyde resin/reactive kaolinite composite synthesis is proposed.

Composites of sodium manganese oxides with enhanced electrochemical performance for sodium-ion batteries: Tailoring properties via controlling microstructure

Composites of Na_(0.44)Mn O_2, Na_(0.7)Mn O_(2.05), and Na_(0.91) Mn O_2 were synthesized by facile solid-state reaction, ball milling, and annealing methods. Two different composites of identical overall composition but drastically different morphologies and microstructures were synthesized. A composite of a hierarchical porous microstructure with primary and secondary particles(i.e., a "meatball-like" microstructure) achieved an excellent stable capacity of 126 m A h g^(-1) after 100 cycles. The rate capability of the composite could be dramatically enhanced by another round of high-energy ball milling and reannealing; subsequently, a composite that was made up of irregular rods was obtained, for which the capacity was improved by more than 230% to achieve ~53 m A h g^(-1) at a particularly high discharge rate of 50 C. This study demonstrated the feasibility of tailoring the electrochemical performance of electrode materials by simply changing their microstructures via facile ball milling and heat treatments, which can be particularly useful for optimizing composite electrodes for sodium-ion batteries.