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Single-crystalline Si3N4 nanobelts (NBs) were successfully synthesized in a size-controlled manner using graphite, nanosilicon and nanosilica powders in N2 gas. The average width of Si3N4 NBs increased with an increase in the flow rate of N2 gas, with 264 nm at 50 ml min−1, 295 nm at 100 ml min−1 and 341 nm at 200 ml min−1. The room-temperature photoluminescence (PL) spectra showed that the synthesized α-Si3N4 nanobelts with three different sizes all had two strong emission peaks located in the yellow and red spectral range, which could be mainly attributed to the incorporation of a small amount of Al in the NBs, and the larger size could also lead to a slight red shift. The Young's modulus of Si3N4 NBs was measured with a hybrid scanning electron microscope/scanning probe microscope (SEM/SPM) system by means of the modulated nanoindentation method. The Young's modulus of Si3N4 NBs strongly depended on their size, decreasing from about 548.6 to 455.1 GPa, which can be explained by surface effects and defect-related effects arising due to their nanometer size. These findings provide a method to tailor the optical and mechanical properties of the NBs in a controlled manner over a wide range of Young's modulus values. [ABSTRACT FROM AUTHOR]

Suspended sediment particle size distribution characteristics not only represent the state of being of the suspended particle, but can also be used to imply the procedure and strength of the hydro-dynamics and re-suspension. Mie theory is used to build the suspended sediment average grain size retrieval model. Results show that suspended sediment backscattering coefficient and the cube of average grain size has ideal linear relationship, with the determination coefficients of the fitting equations all above 0. 93 at four bands (412 nm, 443 nm, 555 nm, 667 nm). The maximal and minimal fitting errors are 16. 632 2% (412 nm) and 20. 314 3% (667 nm), respectively. The suspended sediment backscattering coefficient in the study area was estimated using the quasi-analytical algorithm (QAA) from a MODIS remote sensing reflectance image. Surface water average grain size was estimated by combining the retrieval values of the suspended sediment concentration and the suspended sediment backscattering coefficient. The result shows that values estimated from the inversion model are in good agreement with experimental data from near-shore areas with high suspended sediment content. This study can provide significant supporting data for deep research on land-ocean interaction, marine ecological system evolution, and marine participates in the global carbon cycle. [ABSTRACT FROM AUTHOR]

Abstract: The core–shell structure Ag@Al2(SiO3)3 nanocomposites were prepared by depositing a thin layer of Al2(SiO3)3 on as-synthesized Ag nanostructures through a precipitation reaction of Al2(SO4)3 and Na2SiO3. The controllable morphologies of these core–shell nanocomposites were obtained via tailoring the sizes and morphologies of Ag cores during the synthesis process. The surface plasmon resonance (SPR) analysis on Ag cores indicated different characteristic bands from nanocubes to nanorods. Microstructure analysis by SEM and TEM showed that the obtained Ag@Al2(SiO3)3 have typical core–shell structure and an average shell thickness of 10nm for nanorods and 25nm for nanocubes. The absorption peaks of these Ag@Al2(SiO3)3 nanocomposites are significantly red-shifted comparing with those of uncoated Ag nanostructures. [Copyright &y& Elsevier]

To prepare a coating with a high emissivity and low solar absorption ratio on the surface of aluminum silicate fiber cloth, the sol-gel method was used with silica sol as a binder. In this study, the effects of two white fillers, titanium oxide and zirconia, on the substrate and radiation properties of coatings were compared after heat treatment at 800–1200 °C. The ZrO 2 -based coating had good stability after heat treatment at 800–1200 °C, and maintained its white color, exhibiting solar absorption ratio of approximately 0.14 and emissivity of 0.84. ZrO 2 -based coatings prevented harmful cracking, as observed for the TiO 2 -based coatings after heat treatment, because of the ZrO 2 phase transformation. The ZrO 2 -based coating did not have strong bonding with the substrate, and the substrate strength was improved by maintaining a weak bonding interface. Compared with the TiO 2 -based coatings, which exhibit reduced substrate strength above 1000 °C, the ZrO 2 -based coating was more suitable for the surface of flexible fiber cloths as a temperature-resistant coating with good development prospects. [ABSTRACT FROM AUTHOR]

Cratons play an important role in the evolution of Earth and usually exhibit extremely thick and strong lithosphere roots and low surface heat flow. Most cratons remain in a stable state throughout their long evolutionary process. However, the stability of a few cratons was lost, the thickness of the lithosphere was greatly reduced, and surface heat flow greatly increased. Significant thinning of the lithosphere is one of the most obvious features of craton destruction. However, even within the same area, the lithospheric thickness values estimated from different methods can vary a lot. The thickness disparities between the thermal and seismic lithosphere remain unclear. On the basis of the latest global heat flow data and crustal stratification information, we calculated the thickness of the thermal lithosphere of cratons globally and conducted a detailed comparison to that of the seismic lithosphere. We found that 1) the thickness of the thermal lithosphere of most cratons is more than 150 km, while that of the Bundelkhand, Singhbhum, and upper Yangtze craton ranges from approximately 120–150 km. The thickness of the eastern North China craton, lower Yangtze craton and Wyoming craton ranges from only approximately 80–100 km. 2) For most cratons, the thickness of the seismic lithosphere is tens of kilometers (30–141 km) larger than that of the thermal lithosphere, except for the Wyoming craton, eastern North China craton, upper Yangtze craton, and Dahawar craton. 3) The part between the bottom boundaries of the seismic and thermal lithosphere can be considered as the rheological boundary layer (RBL), which is related to the craton stability. The thicker the RBL is, the higher the craton stability. 4) Due to plate subduction, the water content in the upper mantle is high, the viscosity is low, and the thickness of the RBL of cratons is small. • The thermal lithospheric thickness of most cratons exceeds 150 km. • The seismic lithosphere is thicker than thermal lithosphere for stable cratons. • Different thickness of rheological boundary layer accounts for the disparities. • Destroyed cratons usually exhibit thin rheological boundary layer. • A thick rheological boundary layer exists in stable cratons. [ABSTRACT FROM AUTHOR]

It is important to determine the relationship between the concentration of chlorophyll a (Chla) and the inherent optical properties (IOPs) of ocean water to develop optical models and algorithms that characterize the biogeochemical properties and estimate biological pumping and carbon flux in this environment. However, previous studies reported relatively large variations in the particulate backscattering coefficient (b bp (λ)) and Chla from more eutrophic high-latitude waters to clear oligotrophic waters, especially in oligotrophic oceanic areas where these two variables have little covariation. In this study, we examined the variability of b bp (λ) and Chla in the euphotic layer in oligotrophic areas of the tropical Western Pacific Ocean and determined the sources of these variations by reassessment of in-situ measurements and the biogeochemical-argo (BGC-Argo) database. Our findings identified covariation of b bp (λ) and Chla in the water column below the deep Chla maximum (DCM) layer, and indicated that there was no significant correlation relationship between b bp (λ) and Chla in the upper layer of the DCM. Particles smaller than 3.2 µm that were in the water column above the DCM layer had a large effect on the b bp (λ) in the vertical profile, but particles larger than 3.2 µm and smaller than 10 µm had the largest effect on the b bp (λ) in the water column below the DCM layer. The contribution of non-algal particles (NAPs) to backscattering is up to 50%, which occurs in the water depth of 50 m and not consistent with the distribution of Chla. Phytoplankton and NAPs were modeled as coated spheres and homogeneous spherical particles to simulate the b bp (λ) of the vertical profile by Aden-Kerker method and Mie theory, and the results also indicated that the backscattering caused by particles less than 20 µm were closer to the measured data when they were below and above the DCM layer, respectively. This relationship also reflects the b bp (λ) of particles in the upper water was significantly affected particle size, but b bp (λ) in the lower water was significantly affected by Chla concentration. This effect may have relationship with phytoplankton photoacclimation and the relationship of a phytoplankton biomass maximum with particle size distribution in the water column according to the previous relevant studies. These characteristics also had spatial and seasonal variations due to changes of Chla concentration at the surface and at different depths. There was mostly a linear relationship between Chla and b bp (700) during winter. During other seasons, the relationship between these two variables was better characterized by a power function (or a logarithmic function) in the lower layer of the DCM. The spatial and vertical relationships between the b bp (λ) and Chla and the corresponding variations in the types of particles described in this study provide parameters that can be used for accurate estimation of regional geochemical processes.