Spatial gradient information of density field in SIMP (solid isotropic material with penalization) topology optimization is very useful for imposing overhang angle and minimum length (size) ...manufacturing constraints or achieving shell-infill optimization. However, the computation of density gradient is an approximation since the design space is discretized. There are several operators for this purpose, which arise from the image processing field. This note compares different gradient operators in the context of SIMP topology optimization method and suggests a new computation strategy to improve the accuracy of gradient estimation. We take a case study of spatial gradient-based minimum size constraints. New structural indicator functions are proposed to improve the general applicability of previous gradient-based minimum length constraints. This study is carried out in 2D structure examples to validate the methodology.
This study investigated the effects of soil crust development on the underlying soil properties. The field sampling work was conducted in June 2016 in the Hobq Desert in Inner Mongolia, North China. ...Soil crust samples and 0–6, 6–12, 12–18, 18–24, and 24–30 cm deep underlying soil samples were taken from five representative areas of different soil crust development stages. All samples were analyzed for physicochemical properties, including water content, bulk density, aggregate content, organic matter content, enzyme activities, and microbial biomass carbon and nitrogen. The results showed that the thickness, water content, macro-aggregate (>250 μm) content, organic matter content, microbial biomass, and enzyme activities of the soil crusts gradually increased along the soil crust development gradient, while the bulk density of the soil crusts decreased. Meanwhile, the physicochemical and biological properties of the soils below the algal and moss crusts were significantly ameliorated when compared with the physical crust. Moreover, the amelioration effects were significant in the upper horizons (approx. 0–12 cm deep) and diminished quickly in the deeper soil layers.
The control on the size and morphology of hybrid nanocrystals is essential for the fundamental research and practical applications of these multimaterial nanocrystals with elaborate structures. In ...our work, the ZnO–Au hybrid nanocrystals were prepared by using an aqueous solution method, where hexadecyl trimethyl ammonium bromide, a surfactant, was proved to play an important role in obtaining fine hybrid nanocrystals with good dispersibility. Compared to pure ZnO, the hybrid nanocrystals emitted strong visible light arising from the defects at the ZnO/Au interface.
A large amount of information including indoor spatial structure information and smartphone sensor information can be utilized for indoor localization. However, it remains an open challenge to ...efficiently organize and effectively integrate this data to achieve accurate indoor localization. Knowledge Graphs have powerful intuitive data representation capabilities, semantic and relational processing capabilities, and efficient data storage and feedback mechanisms. Introducing Knowledge Graphs to indoor localization can effectively improve positioning accuracy and subsequently, enrich indoor location-based services. This article presents a Knowledge Graph framework that integrates the basic structure of the indoor environment and various types of smartphone sensing data for indoor localization. This framework consists of two sections: indoor space ontology and mobile sensing data. The indoor space ontology expresses the indoor spatial structure and relationship data, while the sensor sensing data includes a large amount of sensor information generated by pedestrians during indoor activities. Experimental results confirm that the proposed Knowledge Graph framework can achieve efficient indoor localization with good scalability and flexibility under various indoor circumstances.
ZnO–Au hybrid nanocrystals with good dispersibility and uniform size are prepared via a high temperature reflux route. The structure, morphology, interface structure and optical properties were ...characterized by X-ray diffraction high resolution transmission electron microscope and UV–vis absorption spectrophotometer. The formation of hybrid nanocrystals was believed to arise from the heterogeneous nucleation and epitaxial growth, high temperature and surfactant are proposed as the key factors for producing fine and uniform hybrid nanocrystals.
The effect of the Nb
5+
substitution with a charge-compensated strategy in lithium-rich layered oxides (LLOs) Li
1.2
Ni
0.13+x
Co
0.13-x
Mn
0.54-x
Nb
x
O
2
(
x
= 0, 0.01, 0.02, and 0.03) has been ...investigated systematically. A hydroxide co-precipitation method followed by a high-temperature solid-state reaction is adopted in the synthesis process. Structural characterization confirms that the low dose substituting of Nb
5+
in the layered structures forms a solid solution, and the samples show low cation mixing and enlarged Li
+
-diffusing channels, which imply favorable high-rate capability. The initial charge/discharge measurements suggest that the oxygen loss from the network during the delithiation process has been suppressed by the substitution of Nb
5+
due to the formation of robust Nb–O bonds and a decrease in TM-O (TMs are transition metals) covalence. Moreover, these Nb–O bonds contribute to the stabilization of the crystalline framework, resulting in an excellent cycle stability with a mitigated voltage decay.
Protein-disulfide isomerase-like protein of the testis (PDILT), a member of the protein-disulfide isomerase family, is a chaperone essential for the folding of spermatogenesis-specific proteins in ...male postmeiotic germ cells. However, the structural mechanisms that regulate the chaperone function of PDILTs are unknown. Here, we report the structures of human PDILT (hPDILT) determined by X-ray crystallography to 2.4 Å resolution and small-angle X-ray scattering (SAXS). Distinct from previously reported U-like structures of related PDI family proteins, our structures revealed that hPDILT folds into a compact L-like structure in crystals and into an extended chain-like structure in solution. The hydrophobic regions and the hydrophobic pockets in hPDILT, which are important for substrate recognition, were clearly delineated in the crystal structure. Moreover, our results of the SAXS analysis and of structure-based substitutions and truncations indicated that the C-terminal tail in hPDILT is required for suppression of aggregation of denatured proteins, suggesting that the tail is crucial for the chaperone activity of PDILT. Taken together, our findings have identified the critical regions and conformational changes of PDILT that enable and control its activity. These results advance our understanding of the structural mechanisms involved in the chaperone activity of PDILT.
Imaging guided techniques have been increasingly employed to investigate the pharmacokinetics (PK) and biodistribution of nanoparticle based drug delivery systems. In most cases, however, the PK ...profiles of drugs could vary significantly from those of drug delivery carriers upon administration in the blood circulation, which complicates the interpretation of image findings. Herein we applied a genetically encoded luciferase reporter in conjunction with near infrared (NIR) fluorophores to investigate the respective PK profiles of a drug and its carrier in a biodegradable drug delivery system. In this system, a prototype hydrophobic agent, rapamycin (Rapa), was encapsulated into human serum albumin (HSA) to form HSA Rapa nanoparticles, which were then labeled with Cy5 fluorophore to facilitate the fluorescence imaging of HSA carrier. Meanwhile, we employed transgenetic HN12 cells that were modified with a split luciferase reporter, whose bioluminescence function is regulated by Rapa, to reflect the PK profile of the encapsulated agent. It was interesting to discover that there existed an obvious inconsistency of PK behaviors between HSA carrier and rapamycin in vitro and in vivo through near infrared fluorescence imaging (NIFRI) and bioluminescence imaging (BLI) after treatment with Cy5 labeled HSA Rapa. Nevertheless, HSA Rapa nanoparticles manifested favorable in vivo PK and tumor suppression efficacy in a follow-up therapeutic study. The developed strategy of combining a molecular reporter and a fluorophore in this study could be extended to other drug delivery systems to provide profound insights for non-invasive real-time evaluation of PK profiles of drug-loaded nanoparticles in pre-clinical studies.
The photocatalyzed water splitting reaction in aqueous methanol solution is an efficient preparation method for hydrogen and methanal under mild conditions. In this work, metal sulfide-loaded TiO
2
...photocatalysts for hydrogen and methanol production were synthesized by hydrothermal method (180°C/12 h) and characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The crystal structures of the samples are the typical anatase phase of TiO
2
and exhibit a spherical morphology. When TiO
2
was loaded with CoS, ZnS, and Bi
2
S
3
, respectively, the resulting catalysts showed photocatalytic activities for water decomposition to hydrogen in aqueous methanol solution under 300 W Xe lamp irradiation. Among the photocatalysts with various compositions, the 20 wt% CoS/TiO
2
sample with a 2.1 eV band gap showed the maximum photocatalytic activity for the photocatalytic reaction, which indicated that CoS improved the separation ratio of photoexcited electrons and holes. The enhanced activity can be attributed to the intimate junctions that are formed between CoS and TiO
2
, which can reduce the electron-hole recombination. The production rate of hydrogen with 20 wt% CoS/TiO
2
photocatalyst was about 5.6 mmol/g/h, which was 67 times higher than that of pure TiO
2
. The formation rate of HCHO was 1.9 mmol/g/h with 98.7% selectivity. Moreover, the CoS/TiO
2
photocatalyst demonstrated good reusability and stability. In the present study, it is demonstrated that CoS can act as an effective cocatalyst to enhance the photocatalytic hydrogen and methanal production activity of TiO
2
. The highly improved performance of the CoS/TiO
2
composite was mainly ascribed to the efficient charge separation.
PDF
