Engineering the efficient three-dimension hollow cubic carbon from vacuum residuum with enhanced mass transfer ability towards H2O2 production

Constructing efficient carbon material with enhanced mass transfer ability from vacuum residuum(VR)is of prime industrial and scientific significance.Herein,we demonstrated a one-pot synthesis of metal-free and highly symmetric hollow carbon cubes(HCCs)using cost-efficient vacuum residuum(VR)as a C/N/S source.By multi-techniques such as TEM,SEM,Raman,XPS,and XRD,it is found that the CTAB surfactant plays an important role in emulsifying and forming oil-in-water suspension particles.Subsequently,high aromatics contents in VR favor the formation of HCCs shell by graphitization on the surface of Na Cl template.Notably,heavy metals(e.g.,V,Ni)are not enriched in carbon skeleton due to the unique graphitization mechanism.This metal-free HCCs catalyst showed good catalytic stability and high selectivity towards direct and local electrochemical production of hydrogen peroxide(H_(2)O_(2))through two-electron O_(2)reduction due to enhanced mass transfer ability.The results provide a novel avenue to synthesize metal-free cubic carbon material from low-cost and plentiful VR,which are essential to the design of more efficient catalysts for O_(2)reduction to H_(2)O_(2).

Construction of three-dimensional hierarchical porous nitrogen-doped re duce d graphene oxide/hollow cobalt ferrite composite aerogels toward highly efficient electromagnetic wave absorption

The development of graphene-based composites with low density,robust absorption,wide bandwidth and thin thickness remained a great challenge in the field of electromagnetic(EM)absorption.In this work,nitrogen-doped reduced graphene oxide/hollow cobalt ferrite(NRGO/hollow CoFe_(2)O_(4))composite aerogels were constructed by a solvothermal and hydrothermal two-step route.Results demonstrated that the as-fabricated composite aerogels had the ultralow density and a unique three-dimensional(3D)network structure,and lots of hollow CoFe_(2)O_(4)microspheres were almost homogeneously distributed on the wrinkled surfaces of lamellar NRGO.Moreover,superior EM absorbing capacity could be achieved by modulating the ferrite structure,addition amounts of hollow CoFe_(2)O_(4)and thicknesses.It was noteworthy that the NRGO/hollow CoFe_(2)O_(4)composite aerogel with the addition amount of ferrite of 15.0 mg pos-sessed the minimum reflection loss of-44.7 dB and maximum absorption bandwidth of 5.2 GHz(from 12.6 to 17.8 GHz)at a very thin thickness of 1.8 mm and filling ratio of 15.0 wt.%.Furthermore,the possible EM attenuation mechanism had been proposed.The results of this work would be helpful for developing RGO-based 3D composites as lightweight,thin and highly efficient EM wave absorbers.

Magnetic Resonance Three-dimensional Cube Technique in the Measurement of Piglet Femoral Anteversion

Background： The accurate measurement of the femoral anteversion （FA） angle is always a topic of much debate in the orthopedic surgery and radiology research. We aimed to explore a new FA measurement method to acquire accurate results without radiation damage using piglet model. Methods： A total of thirty piglets were assigned to two groups based on the age. Bilateral femora were imaged with 3.0-T magnetic resonance （MR） and 64-slice computed tomography （CT） examinations on all piglets. FA was measured on MR-three-dimensional （3D） postprocessing software with a four-step method： initial validation of the femoral condylar axis, validation of the condylar plane, validation of the femoral neck axis, and line-plane angle measurement of FA. After MR and CT examinations, all piglets were sacrificed and their degree of FA was measured using their excised, dried femora. MR, CT, and dried-femur measurement results were analyzed statistically; M R and CT measurements were compared for accuracy against each other and against the gold standard dried femur measurement. Results： In both groups, the mean FA value measured by MR was lower than that measured by CT. A statistically significant difference was observed between CT- and dried-femur measurements but not between MR- and dried-femur measurements. A higher correlation （0.783 vs. 0.408） and a higher consistency （0.863 vs. 0.578） with dried-femur measurement results were seen for MR measurements than CT measurements in the 1 -week age group. However, in the 8-week age group, similar correlations （0.707 vs. 0.669） and consistencies （0.864 vs. 0.82 l ） were observed. Conclusions： Noninvasive MR-3D-Cube reconstruction was able to accurately measure FA in piglets. Particularly in the 1-week age group with a larger proportion of cartilaginous structures, the correlation and consistency between MR- and dried-femur measurement results were higher than those between CT- and dried-femur measurements, suggesting that MR may be a new useful examination tool for FA-related diseases in children.

空心锥体棱镜研制工艺研究

介绍一种空心锥体棱镜加工工艺。首先,采用光学冷加工技术加工三个玻璃基板,并进行滚外圆和镀膜处理;其次,利用夹具初步固定三个基板,并在粘贴区域涂胶;最后,采用自准直平行光管对空心锥体棱镜的核心技术指标进行实时监测,紫外灯进行固化处理,控制成型。实践证明:该工艺可以对空心锥体的二面角进行精确控制,适合大口径空心锥体棱镜的加工。

Synthesis of Hollow Three-Dimensional Channels LiNi_(0.5)Mn_(1.5)O_4 Microsphere by PEO Soft Template Assisted with Solvothermal Method

A appropriate size with three-dimension(3 D) channels for lithium diffusion plays an important role in constructing highperforming LiNi_(0.5)Mn_(1.5)O_4(LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li~+ intercalation/deintercalation. In this work, an e fficient method for designing the hollow LNMO microsphere with 3 D channels structure by using polyethylene oxide(PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3 D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g~(-1) at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3 D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion.

A three-dimensional hollow graphene fiber microelectrode with shrink-effect-enabled enzyme immobilization for sensor applications

Microelectrodes are a type of electrode with microscopic dimension, and due to their rapid diffusing rates, high electrical current densities and signal-to-noise ratios, they can help improve the detection sensitivity for various analytes [1]. Investigations on the fabrication and the application of microelectrodes are highly relevant. Fiber-type microelectrodes with one-dimensional (ID) microstructures that possess ID diffusion, particularly carbon fiber microelectrodes, have been widely fabricated and used in many different types of sensors due to their low cost, small volume, portability, and good biocompatibility [1,2]. However, poor electrocatalytic activity and low response currents preclude the applications of carbon fiber microelectrodes in sensors.

板式空心角锥棱镜的研制

在远距离测量、特别是距离达到一公里左右时,角锥棱镜几乎是唯一可行的反射器件。远距离测量的需求是增大角锥棱镜的通光口径,以便于捕捉目标,并增大反射光的能量。常用的整体式角锥棱镜,以及国外的柱式空心角锥棱镜,随着通光口径的增大,都会显著增加棱镜的体积与重量,造成使用不便与工艺困难。解决办法是采用板式结构,经试验,通光口径为80mm的板式空心角锥棱镜,工作距离可达一公里以上,出射光对入射光的平行度达角秒级,体积与重量在可以接受的范围内,而且可以降低工艺难度。

煤矸石玻化微珠保温混凝土初探

玻化微珠保温混凝土作为一种集承重、保温于一体的绿色建筑材料,在工程上的应用正在逐步推广。在玻化微珠保温混凝土的基础上,用煤矸石取代了其中的部分或全部粗骨料制成了一种新型绿色建筑材料——煤矸石玻化微珠保温混凝土。通过对5种不同煤矸石掺量的玻化微珠保温混凝土立方体抗压强度和导热系数进行分析可知,参照C50强度等级普通混凝土配制的煤矸石玻化微珠保温混凝土抗压强度能够达到C30~C45混凝土的设计值,并仍具有玻化微珠保温混凝土良好的保温性能。

空心角隅棱镜在激光干涉测角中的应用

阐述了激光小角度测量装置中使用的实心角隅棱镜由于制造和安装误差对测量结果所造成的影响,同时提出利用空心角隅棱镜可以解决问题的理论依据,通过应用实验效果对理论给予验证。

中空二氧化锰制备及其电化学性能研究

制备出两种形态的MnO2,中空微球和中空微方,采用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(HRTEM)和N2吸脱附对两种材料进行了表征,结果显示中空微球具有较小的粒径和较大的比表面积。将两种材料应用于电容器,中空微球具有更优异的电化学性能,在0.1A/g电流密度下的比电容为263F/g,当电流密度增大至5A/g时,比电容为157F/g,容量保持率高达60%。

三维空心体织物预制件设计研究

借鉴三维空心正方体折纸原理和成型方法,分层分区域设计了三维空心正方体织物结构件,在普通提花织机上实现了三维空心正方体织物结构预制件的一次成型织造。结果表明:采用正交结构、角联锁编织结构为基础组织,合理设计不同层、不同区域织物组织结构和各层间纬纱联接路径,可以完成空心正方体的整体结构设计,达到特殊结构件织物一次成型织造工艺要求,为特殊箱体造型织物预制件一次成型结构提供设计方法和织造工艺技术支持。

高温作用后玻化微珠保温混凝土受压力学性能试验研究

为了研究玻化微珠保温混凝土高温(火灾)后的受压力学性能,设计了玻化微珠保温混凝土和普通混凝土标准受压试件的高温及抗压试验。根据试验结果,分析了玻化微珠保温混凝土和普通混凝土经受高温后的立方体抗压和轴心抗压破坏形态的异同,总结了2种受压强度在不同高温作用后的损失规律,并采用最小二乘法回归了玻化微珠保温混凝土高温后受压强度以及其"轴压比"随温度变化的解析表达式。结果表明:玻化微珠保温混凝土和普通混凝土受压破坏形态基本一致,但2种混凝土经受高温后的破坏均比常温下严重;受压强度随温度变化的拟合公式可为玻化微珠保温混凝土的结构设计提供理论参考。

3D Bioprinting:A Novel Avenue for Manufacturing Tissues and Organs

Three-dimensional(3D)bioprinting is a rapidly growing technology that has been widely used in tissue engineering,disease studies,and drug screening.It provides the unprecedented capacity of depositing various types of biomaterials,cells,and biomolecules in a layer-by-layer fashion,with precisely controlled spatial distribution.This technology is expected to address the organ-shortage issue in the future.In this review,we first introduce three categories of 3D bioprinting strategies:inkjet-based printing(IBP),extrusion-based printing(EBP),and light-based printing(LBP).Biomaterials and cells,which are normally referred to as“bioinks,”are then discussed.We also systematically describe the recent advancements of 3D bioprinting in fabricating cell-laden artificial tissues and organs with solid or hollow structures,including cartilage,bone,skin,muscle,vascular network,and so on.The development of organs-onchips utilizing 3D bioprinting technology for drug discovery and toxicity testing is reviewed as well.Finally,the main challenges in current studies and an outlook of the future research of 3D bioprinting are discussed.

偏锡酸锌空心立方体的合成及其乙醇气敏性能

采用简易的一步共沉淀法合成偏锡酸锌空心立方体.利用扫描电子、透射电子显微镜、X射线衍射、固体紫外、氮气吸附比表面测试等表征手段对该材料形貌和结构进行表征,结果表明,所合成的偏锡酸锌空心立方体边长约为1.4μm,立方体的壁厚约为210 nm,而且尺寸均匀.气敏性能测试研究表明,偏锡酸锌空心立方体材料对乙醇表现出优异的气敏性能,其最佳工作温度为175℃,并且对体积分数为百万分之一的乙醇气体的响应为1.7.因此,偏锡酸锌空心立方体材料可以做为一种优良的气敏材料.

Surface chlorine doped perovskite‐type cobaltate lanthanum for water oxidation

Rationally manipulating the in‐situ formed catalytically active surface of catalysts remains a great challenge for a highly efficient water electrolysis.Here,we report a cationic oxidation method which can adjust the leaching of the in‐situ catalyst and promote the reconstruction of dynamic surface for the oxygen evolution reaction(OER).The chlorine doping can reduce the possibility of triggering in‐situ cobalt oxidation and chlorine leaching,leading to a transformation of the surface chlorine doped LaCoO_(3)(Cl‐LaCoO_(3))into an intricate amorphous(oxygen)hydroxide phase.And thus,Cl‐LaCoO_(3)nanocrystals shows an ultralow overpotential of 342 mV at the current density of 10 mA cm^(–2)and Tafel slope of 76.2 mV dec–1.Surface reconstructed Cl‐LaCoO_(3)is better than many of the most advanced OER catalysts and has proven significant stability.This work provides a new prospect for designing a high‐efficiency electrocatalyst with optimized perovskite‐structure in renewable energy system.

基于ZIF-8的中空立方体的制备及锂离子电池应用

材料的结构形貌对其应用起到至关重要的作用,中空结构因其独特的结构特征广泛应用于催化,气体储存,锂离子电池等领域。本文首先通过调控表面活性剂CTAB制备出大小一致的沸石咪哩骨架(ZIF-8)立方体,然后利用TEOS和多巴胺来固定立方体ZIF-8的形貌,接着通过退火以及刻饰的方法获得SiO2@C的中空立方体结构。通过X射线衍射、扫描电镜、透射电镜等一系列表征方法可知,采用模板法制备出的SiO2@C不仅在尺寸上保持大小的高度一致并且具有规则的立方体结构。作为中空结构在实际应用中的典型例子,将SiO2@C作为模板制备出的中空SiO2@C@MoS2结构,具有优异的锂离子储存性能。在100mA/g恒流充放电下循环100次后保持着930mAh/g的放电比容量,且在此过程中充放电循环效率均在95%以上。

中空立方体Au-TiO_2纳米复合材料的制备、表征及气敏性能

以Cu_2O为模板,采用水热法合成中空立方体Au-TiO_2纳米复合材料,通过XRD、EDX、SEM和TEM对该复合材料的结构和形貌进行表征,探讨了该中空立方体结构的形成过程,并测试了该复合材料的气敏性能。结果表明,Cu_2O模板尺寸约为1μm,TiO_2作为中空立方体结构的框架,尺寸约为20nm,Au颗粒分散在中空立方体的表面;中空立方体Au-TiO_2纳米复合材料具有良好的丙酮敏感性,在250℃下对100×10-6的丙酮的灵敏度达到8.2。

Rational design of stratified material with spatially separated catalytic sites as an efficient overall water-splitting photocatalyst

The development of metal sulfide catalysts with remarkable activity toward efficient overall photocatalytic water splitting remains challenging owing to the dominant charge recombination and deficient catalytic active sites.Moreover,in the process of water oxidation catalysis,the inhibition of severe photocorrosion is an immense task,requiring effective photogenic hole-transfer kinetics.Herein,stratified Co-MnO_(2)@CdS/CoS hollow cubes with spatially separated catalytic sites were rationally designed and fabricated as highly efficient controllable catalysts for photocatalytic overall water splitting.The unique self-templated method,including a continuous anion/cation-exchange reaction,integrates a Co-doped oxidation co-catalyst(Co-MnO_(2))and a reduction co-catalyst(CoS)on the nanocubes with uniform interface contact and ultrathin two-dimensional(2D)nanometer sheets.We demonstrate that the stratified Co-MnO_(2)@CdS/CoS hollow cubes can provide an abundance of active sites for surface redox reactions and contribute to the separation and migration of the photoionization charge carriers.In particular,CoS nanoparticles dispersed on the walls of CdS hollow cubes were identified as reduction co-catalysts accelerating hydrogen generation,while Co-MnO_(2) nanosheets attached to the inner walls of the CdS hollow cube were oxidation co-catalysts,promoting oxygen evolution dynamics.Benefiting from the desirable structural and compositional advantages,optimized stratification of Co-MnO_(2)@CdS/CoS nanocubes provided a catalytic system devoid of precious metals,which exhibited a remarkable overall photocatalytic water-splitting rate(735.4(H_(2))and 361.1(O_(2))μmol h^(−1) g^(−1)),being among the highest values reported thus far for CdS-based catalysts.Moreover,an apparent quantum efficiency(AQE)of 1.32%was achieved for hydrogen evolution at 420 nm.This study emphasizes the importance of rational design on the structure and composition of photocatalysts for overall water splitting.

Determine the position of nanoparticles in cells by using surfaceenhanced Raman three-dimensional imaging

The development of efficient three-dimensional cell imaging technology is a necessary means to study cell composition and structure,especially to track and monitor the phagocytosis process of nanoparticles by cells.Herein,we prepared a MoO_(2)hollow nanosphere with a strong surface plasmon resonance effect in the visible light region,which exhibited an excellent surface enhanced Raman scattering effect.When the 4-mercaptobenzoic acid(4-MBA)molecules are modified,it can be efficiently used as Raman probe molecules to perform clear three-dimensional cell imaging.No matter when the nanoparticles are located inside the cell,outside the cell or partly inside the cell,they all can be clearly presented by this enhanced Raman probe molecule.These results provide a rapid and accurate method for three-dimensional imaging of cells,especially for tracking the phagocytosis of nanoparticles.

BDF现浇混凝土空心楼盖施工工艺及技术经济分析

BDF薄壁箱体现浇混凝土空心楼盖是近年来新开发的现浇混凝土空心楼盖内模形式,其具有拓展实用空间、降低综合造价、缩短施工工期、提高隔音隔热性能、免吊顶装饰、减少消防隐患等特点.详细介绍了BDF薄壁箱体现浇混凝土空心楼盖的施工工艺方法,同时分析了采用BDF薄壁箱体现浇混凝土空心楼盖所产生的综合效益,可对类似的工程起到一定借鉴作用.