Synthesis method of novel Gd2O3@Fe3O4 nanocomposite modified by dextrose capping agent

In current study, gadolinium oxide was heterogeneously formed on the surface of iron oxide nanoparticles and further modified with dextrose capping agent to be used in biomedical applications, especially for contrast enhancement in MR images. First, two types of iron oxide nanoparticles were prepared at 25 and 80 ^°C via simple coprecipitaion method. Then, gadolinium oxide nanoparticles were synthesized through a consecutive precipitation process on previously formed iron oxide seeds in an aqueous media and subsequent annealing at 300 ^°C. Finally, dextrose was used as capping agent to stabilize nanocomposites in a colloidal suspension. X-ray diffraction (XRD), Scanning and Transmission electron microscopy, Dynamic Laser Scattering (DLS), Fourier-Transform Infrared Spectroscopy (FTIR), and Magnetometery (VSM) techniques were employed for nanocomposites investigation and MTT-assay method used for viability assessment of colloidal samples. Measurements based on Scherrer equation from XRD patterns showed that increasing coprecipitation temperature resulted bigger iron oxide crystallites. The iron oxide crystallite size was increased from 15.1 to 28.1 nm. Precipitation process led to gadolinium oxide formation with 30.7 and 38.8 nm crystallite sizes, respectively. TEM images revealed that iron oxide agglomerates were encapsulated in gadolinium oxide surroundings. Hydrodynamic size of the coated nanoparticles with dextrose was 208 and 247 nm. In VSM examinations, nanocomposites did not display coercive field and the saturation magnetization was 1.93 emu/g. MTT-assay results showed 80% viability in 285 μg nanocomposites containing 96.9 μg [Fe] and 11.4 μg [Gd].     

Laboratory pull-out tests using bamboo and polymer geogrids including a case study

This study investigates the interaction between soil and geogrids by using both direct shear and pull-out tests and applied the results to a case study. A polymer geogrid and bamboo grids were used with clayey sand and weathered clay as backfill since these materials are readily available in Thailand. The results indicated that the interaction between soil and reinforcement consists of: (a) the adhesion between soil and reinforcement on the solid surface area of the geogrid; and (b) the bearing capacity of soil in front of all transverse members of the geogrids which behaved as a strip footing embedded in the soil. The proposed design procedure for pull-out resistance agreed fairly well with the laboratory pull-out test results. In addition, it was observed that bamboo grids have higher pull-out resistance per unit area than the polymer geogrids. Moreover, the cohesive fill proved to be quite effective when used with geogrid reinforcement. Finally, the proposed design procedure and test results were applied to a case study on an irrigation canal bank repaired by the Public Works Department of Thailand using cohesive backfill and Tensar SS2 geogrids resulting in much improved slope stability.     

高效丢糟纤维素分解菌的筛选及产酶研究

从白酒丢糟堆腐物中筛选出5株分解丢糟纤维素能力强的菌株,以其中降解能力最强的绿色木霉S7为出发菌株。通过对其固态发酵产酶条件的单因素优化试验,初步确定其固体培养基质中丢糟粉与麸皮的最适质量比为4∶1,硫酸铵2%,初始pH值为4.0,30～35℃发酵96 h,羧甲基纤维素酶活和滤纸酶活分别达到57.08μg/min.mL和26.02μg/min.mL。     

Pyrolysis of Mississippi lignite in a fixed bed

The lignite deposits in Mississippi make up approximately 25 percent of the Gulf Coast deposit. To date, the limited number of studies on this lignite have chiefly been by Phillips Coal [1] and investigators in Mississippi [2,3]. This lignite, which is high in ash and moisture, was pyrolyzed in a 2.54 cm (1 in.) diameter fixed bed pyrolyzer under a helium atmosphere at temperatures ranging from 400°C to 950°C. The loss of volatile matter increased with increasing ultimate temperature producing weight losses 20–25% greater than the proximate analysis at 900°C. The yield of tar was found to decrease with temperature while volumetric gas production increased with the ultimate temperature. Hydrogen and carbon monoxide yields increased dramatically above 750°C. The maximum yield of gas was 375 ml/g daf lignite and was achieved at and above 815°C.     

Effect of Yb3+ concentration on the green-yellow upconversion emission of SrGe4O9:Er3+ phosphors

This work presents the structural, morphological and luminescent, properties of SrGe₄O₉ (SGO):Er³⁺,Yb³⁺ phosphors. These phosphors were synthesized by simple combustion synthesis and subsequently annealed at 1100 °C. The XRD patterns revealed that all the SGO samples doped with Yb³⁺ concentrations from 2 to 10 at.% presented a trigonal pure phase (the Er³⁺ concentration was fixed to 1 at.%). The morphology of the SGO samples was analyzed by scanning electron microscopy and found that they are formed by microparticles with irregular shapes and average sizes in the range of 0.2 μm–3 μm. The luminescence measurements of the SGO:Er³⁺,Yb³⁺ samples showed the presence of two main emission bands at 551 nm (green) and at 662 nm (red) under excitation at 980 nm, which are associated to Er³⁺ transitions. For Yb concentration of 2 and 3 at.% the green band dominated, but the red band became more intense for Yb concentrations above 5 at.%. As result, the CIE coordinate changed from the green to the yellow region. The increase for the Yb content from 2 to 10 at.% also enhanced of the NIR emission of Er³⁺ ≈5 times and the maximum upconversion emission was observed for 8% of Yb concentration. Further, the surface of the SGO samples was analyzed by the FTIR technique in order to find OH groups which are common luminescent quenching centers, but these groups were not detected on the samples. Since the SGO samples presented tunable emission, absence of OH groups on their surface and stable crystalline structure for high Yb dopant concentrations, they could be good candidates as phosphors for solid state lighting or displays applications.     

Regulating the multifactor during wet chemical synthesis to obtain calcium phosphate powders with controllable phase purity for bone repair

Calcium phosphate ceramics are widely used as bone repair materials owing to their excellent biocompatibility, bone conductivity, bone induction, and degradability. Although there are many methods for synthesizing calcium phosphate and controlling its phase composition, it is necessary to explore effective preparation methods by understanding the formation of calcium phosphate and its influencing factors. In this study, calcium phosphate powders with controllable phase compositions were synthesized using a wet chemical precipitation method by adjusting the process parameters (aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration). Subsequently, a certain biphasic proportion of (biphasic calcium phosphate, BCP) products was prepared, and pure (β-tricalcium phosphate, β-TCP) can be obtained according to the customer's requirements. BCP ceramics with desired phase compositions were obtained by pressing and sintering different calcium-deficient powders. Specifically, β-TCP powder with a purity of 99.83 wt% was obtained when the aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration were 0 h, 50% ethanol, 1, 0.27 M, and 0.0135 M, respectively. The BCP synthesized in this study shows great application potential in the field of bone tissue repair materials.     

安徽白象山铁选厂一段球磨优化及离散元仿真模拟分析

针对安徽白象山铁选厂一段球磨指标进行优化试验研究,对矿石进行力学性质测定、球磨机给矿筛分,按照段式球径半理论公式初步确定推荐方案为m(Φ60):m(Φ50):m(Φ40):m(Φ30)=20:30:15:35,设置偏大及偏小方案作为对比,通过磨矿对比试验得出,推荐方案较现场方案+0.15 mm级别产率下降11.24百分点,(-0.15+0.10) mm、(-0.074+0.019) mm级别产率分别提高6.55百分点、9.88百分点,磨矿技术效率提高7.57百分点;离散元仿真结果表明,推荐方案法向碰撞能量较现场方案仅降低4.15百分点,切向碰撞能量较现场提高69.04百分点,综合比较推荐方案全面优于现场方案。      

Ca2+ enhances algal photolysis hydrogen production by improving the direct and indirect pathways

In this study, Ca²⁺ was applied to enhance the photolysis H₂ production of Chlamydomonas reinhardtii grown in pure culture or co-cultivated with bacterium. With addition of Ca²⁺, the chlorophyll and protein contents in algal cells were maintained at high levels and the reactive oxygen species (ROS) were scavenged to tolerable levels by activities of catalase (CAT) and superoxide dismutase (SOD). High chlorophyll and low ROS are benefit to protect the photosystem II (PS II) activity that responsible for the direct photolysis H₂ production. Moreover, addition of Ca²⁺ was able to promote the acetic acid assimilation as well as the starch synthesis. The starch degradation, in return, contributed to the H₂ production via the indirect photolysis pathway. Based on the improvements of direct and indirect photolysis pathways, the H₂ production of algae grown in co-cultivation adding with 5 mM Ca²⁺ reached a maximum value of 306 mL L⁻¹, which was 2.4 times higher than the production without Ca²⁺ addition. This study gives an efficient and easy strategy to improve the algal photolysis H₂ production, and gets an insight into the mechanisms of the improvement.     

Revealing unconventional host–guest complexation at nanostructured interface by surface-enhanced Raman spectroscopy

Interfacial host–guest complexation offers a versatile way to functionalize nanomaterials. However, the complicated interfacial environment and trace amounts of...