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Sample records for hierarchical micro-nano structures

  1. Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

    Institute of Scientific and Technical Information of China (English)

    Weiyan Meng; Yanmin Zhou; Yanjing Zhang; Qing Cai; Liming Yang; Jinghui Zhao; Chnnyan Li

    2011-01-01

    In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hierarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching (EE). MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched (SLA) as well as Machined (M) surfaces respectively. The results show significant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

  2. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis.

    Science.gov (United States)

    Nozaki, Kosuke; Shinonaga, Togo; Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao; Tsukamoto, Masahiro; Yamashita, Kimihiro; Nagai, Akiko

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni-Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol.

  3. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, Kosuke [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Shinonaga, Togo [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Tsukamoto, Masahiro [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yamashita, Kimihiro [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Nagai, Akiko, E-mail: nag-bcr@tmd.ac.jp [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan)

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni–Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol. - Highlights: • Hierarchical micro/nano-structures were created on nitinol using a femtosecond laser. • The nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. • Endothelial cells aligned along the nano-structures • Platelets failed to adhere to the micro/nano-surface.

  4. Fabrication of micro/nano hierarchical structures with analysis on the surface mechanics

    Science.gov (United States)

    Jheng, Yu-Sheng; Lee, Yeeu-Chang

    2016-10-01

    Biomimicry refers to the imitation of mechanisms and features found in living creatures using artificial methods. This study used optical lithography, colloidal lithography, and dry etching to mimic the micro/nano hierarchical structures covering the soles of gecko feet. We measured the static contact angle and contact angle hysteresis to reveal the behavior of liquid drops on the hierarchical structures. Pulling tests were also performed to measure the resistance of movement between the hierarchical structures and a testing plate. Our results reveal that hierarchical structures at the micro-/nano-scale are considerably hydrophobic, they provide good flow characteristics, and they generate more contact force than do surfaces with micro-scale cylindrical structures.

  5. Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin

    2016-05-01

    Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

  6. Osteogenic activity of titanium surfaces with hierarchical micro-/nano-structures obtained by hydrofluoric acid treatment

    Science.gov (United States)

    Liang, Jianfei; Xu, Shanshan; Shen, Mingming; Cheng, Bingkun; Li, Yongfeng; Liu, Xiangwei; Qin, Dongze; Bellare, Anuj; Kong, Liang

    2017-01-01

    An easier method for constructing the hierarchical micro-/nano-structures on the surface of dental implants in the clinic is needed. In this study, three different titanium surfaces with microscale grooves (width 0.5–1, 1–1.5, and 1.5–2 μm) and nanoscale nanoparticles (diameter 20–30, 30–50, and 50–100 nm, respectively) were obtained by treatment with different concentrations of hydrofluoric acid (HF) and at different etching times (1%, 3 min; 0.5%, 12 min; and 1.5%, 12 min, respectively; denoted as groups HF1, HF2, and HF3). The biological response to the three different titanium surfaces was evaluated by in vitro human bone marrow-derived mesenchymal stem cell (hBMMSC) experiments and in vivo animal experiments. The results showed that cell adhesion, proliferation, alkaline phosphatase activity, and mineralization of hBMMSCs were increased in the HF3 group. After the different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in groups HF1, HF2, and HF3 was 33.17%±2.2%, 33.82%±3.42%, and 41.04%±3.08%, respectively. Moreover, the maximal pullout force in groups HF1, HF2, and HF3 was 57.92±2.88, 57.83±4.09, and 67.44±6.14 N, respectively. The results showed that group HF3 with large micron grooves (1.5–2.0 μm) and large nanoparticles (50–100 nm) showed the best bio-functionality for the hBMMSC response and osseointegration in animal experiments compared with other groups.

  7. Bioinspired synthesis of hierarchically micro/nano-structured CuI tetrahedron and its potential application as adsorbent for Cd(II) with high removal capacity.

    Science.gov (United States)

    Gao, Shuyan; Yang, Jianmao; Li, Zhengdao; Jia, Xiaoxia; Chen, Yanli

    2012-04-15

    An environment friendly bioinspired strategy for synthesizing hierarchically micro/nano-structured CuI tetrahedron has been developed by combining the stabilization and the reduction performances of l-tryptophan together. A possible growth mechanism of such hierarchical tetrahedron is tentatively proposed. Remarkably, such CuI tetrahedron is found to possess high removal capacity for poisonous Cd(II) ions, 136.3mg/g, and ideal reusability. This is ascribed to the hierarchical micro/nano-structure and chemical adsorption mechanism, which shows great advantages over the traditional nano-scaled adsorbents. These interesting results stand out the promising applications of such hierarchically micro/nano-structured materials in environment. It is also a good example for the organic combination of green chemistry and nanotechnologies for the treatment of contaminated water.

  8. Hierarchical micro-nano structured Ti6Al4V surface topography via two-step etching process for enhanced hydrophilicity and osteoblastic responses.

    Science.gov (United States)

    Moon, Byeong-Seok; Kim, Sungwon; Kim, Hyoun-Ee; Jang, Tae-Sik

    2017-04-01

    Hierarchical micro-nano (HMN) surface structuring of dental implants is a fascinating strategy for achieving fast and mechanically stable fixation due to the synergetic effect of micro- and nano-scale surface roughness with surrounding tissues. However, the introduction of a well-defined nanostructure on a microstructure having complex surface geometry is still challenging. As a means of fabricating HMN surface on Ti6Al4V-ELI, target-ion induced plasma sputtering (TIPS) was used onto a sand-blasted, large-grit and acid-etched substrate. The HMN surface topography was simply controlled by adjusting the tantalum (Ta) target power of the TIPS technique, which is directly related to the Ta ion flux and the surface chemical composition of the substrate. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and laser scanning microscopy (LSM) verified that well-defined nano-patterned surface structures with a depth of ~300 to 400nm and a width of ~60 to 70nm were uniformly distributed and followed the complex micron-sized surface geometry. In vitro cellular responses of pre-osteoblast cells (MC3T3-E1) were assessed by attachment and proliferation of cells on flat, nano-roughened, micro-roughened, and an HMN surface structure of Ti6Al4V-ELI. Moreover, an in vivo dog mandible defect model study was used to investigate the biological effect of the HMN surface structure compared with the micro-roughened surface. The results showed that the surface nanostructure significantly increased the cellular activities of flat and micro-roughened Ti, and the bone-to-implant contact area and new bone volume were significantly improved on the HMN surface structured Ti. These results support the idea that an HMN surface structure on Ti6Al4V-ELI alloy has great potential for enhancing the biological performance of dental implants.

  9. Fabrication and Cell Responsive Behavior of Macroporous PLLA/Gelatin Composite Scaffold with Hierarchical Micro-Nano Pore Structure

    Directory of Open Access Journals (Sweden)

    Kedong Song

    2015-03-01

    Full Text Available Scaffolds providing a 3D environment which can effectively promote the adhesion, proliferation and differentiation of cells are crucial to tissue regeneration. In this study, the poly-l-lactic acid (PLLA scaffold with hierarchical pore structural was fabricated via two-step thermally induced phase separation (TIPS. To mimic both physical architecture and chemical composite of natural bone extracellular matrix (ECM, gelatin fibers were introduced into the pores of PLLA scaffolds and formed 3D network structure via TIPS. Human adipose tissue-derived stem cells (ADSCs were harvested and seeded into PLLA/gel hybrid scaffolds and cultured in vitro for biocompatibility assay. The surface morphology, porosity and compressive modulus of scaffolds were characterized by scanning electron microscopy (SEM, density analysis and compression test respectively. The results showed that hybrid scaffolds had high porosity (91.62%, a good compressive modulus (2.79 ± 0.20 MPa, nanometer fibers (diameter around 186.39~354.30 nm and different grades of pore size from 7.41 ± 2.64 nm to 387.94 ± 102.48 nm. The scaffolds with mild hydrolysis by NaOH were modified by 1-ethyl-3-(3-dimethyl ami-nopropyl carbodiimide/N-hydroxysuccinimide (EDC/NHS. Gelatin was performed onto PLLA scaffold via TIPS aiming at enhancement cell-material interaction. In comparison with PLLA scaffold, the PLLA/gel scaffold had better biological performance and the mechanical properties because the gelatin fibers homogeneously distributed in each pore of PLLA scaffold and formed 3D network structure.

  10. Hierarchically structured superhydrophobic coatings fabricated by successive Langmuir-Blodgett deposition of micro-/nano-sized particles and surface silanization.

    Science.gov (United States)

    Tsai, Ping-Szu; Yang, Yu-Min; Lee, Yuh-Lang

    2007-11-21

    The present study demonstrates the creation of a stable, superhydrophobic surface by coupling of successive Langmuir-Blodgett (LB) depositions of micro- and nano-sized (1.5 µm/50 nm, 1.0 µm/50 nm, and 0.5 µm/50 nm) silica particles on a glass substrate with the formation of a self-assembled monolayer of dodecyltrichlorosilane on the surface of the particulate film. Particulate films, in which one layer of 50 nm particles was deposited over one to five sublayers of larger micro-sized particles, with hierarchical surface roughness and superhydrophobicity, were successfully fabricated. Furthermore, the present 'two-scale' (micro- and nano-sized particles) approach is superior to the previous 'one-scale' (micro-sized particles) approach in that both higher advancing contact angle and lower contact angle hysteresis can be realized. Experimental results revealed that the superhydrophobicity exhibited by as-fabricated particulate films with different sublayer particle diameters increases in the order of 0.5 µm>1.0 µm>1.5 µm. However, no clear trend between sublayer number and surface superhydrophobicity could be discerned. An explanation of superhydrophobicity based on the surface roughness introduced by two-scale particles is also proposed.

  11. Hierarchically structured superhydrophobic coatings fabricated by successive Langmuir-Blodgett deposition of micro-/nano-sized particles and surface silanization

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, P-S; Yang, Y-M; Lee, Y-L [Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2007-11-21

    The present study demonstrates the creation of a stable, superhydrophobic surface by coupling of successive Langmuir-Blodgett (LB) depositions of micro- and nano-sized (1.5 {mu}m/50 nm, 1.0 {mu}m/50 nm, and 0.5 {mu}m/50 nm) silica particles on a glass substrate with the formation of a self-assembled monolayer of dodecyltrichlorosilane on the surface of the particulate film. Particulate films, in which one layer of 50 nm particles was deposited over one to five sublayers of larger micro-sized particles, with hierarchical surface roughness and superhydrophobicity, were successfully fabricated. Furthermore, the present 'two-scale' (micro- and nano-sized particles) approach is superior to the previous 'one-scale' (micro-sized particles) approach in that both higher advancing contact angle and lower contact angle hysteresis can be realized. Experimental results revealed that the superhydrophobicity exhibited by as-fabricated particulate films with different sublayer particle diameters increases in the order of 0.5 {mu}m>1.0 {mu}m>1.5 {mu}m. However, no clear trend between sublayer number and surface superhydrophobicity could be discerned. An explanation of superhydrophobicity based on the surface roughness introduced by two-scale particles is also proposed.

  12. Magnetic Micro/Nano Structures for Biological Manipulation

    Science.gov (United States)

    Huang, Chen-Yu; Hsieh, Teng-Fu; Chang, Wei-Chieh; Yeh, Kun-Chieh; Hsu, Ming-Shinn; Chang, Ching-Ray; Chen, Jiann-Yeu; Wei, Zung-Hang

    2016-05-01

    Biomanipulation based on micro/nano structures is an attractive approach for biotechnology. To manipulate biological systems by magnetic forces, the magnetic labeling technology utilized magnetic nanoparticles (MNPs) as a common rule. Ferrofluid, well-dispersed MNPs, can be used for magnetic modification of the surface or as molds to form organized microstructures. For magnetic-based micro/nano structures, different methods to modulate magnetic field at the microscale have been developed. Specifically, this review focused on a new strategy which uses the concept of micromagnetism of patterned magnetic thin film with specific domain walls configurations to generate stable magnetic poles for cell patterning.

  13. The influence of hierarchical hybrid micro/nano-textured titanium surface with titania nanotubes on osteoblast functions.

    Science.gov (United States)

    Zhao, Lingzhou; Mei, Shenglin; Chu, Paul K; Zhang, Yumei; Wu, Zhifen

    2010-07-01

    Hierarchical hybrid micro/nano-textured titanium surface topographies with titania nanotubes were produced by simple acid etching followed by anodization to mimic the hierarchical structure of bone tissues. Primary rat osteoblasts were used to evaluate the bioactivity. The microtopography formed by acid etching of titanium induced inconsistent osteoblast functions with initial cell adhesion and osteogenesis-related gene expression being dramatically enhanced while other cell behaviors such as proliferation, intracellular total protein synthesis and alkaline phosphatase activity, collagen secretion, and extracellular matrix mineralization being depressed. In comparison, addition of nanotubes to the microtopography led to enhancement of multiple osteoblast functions. Nearly all the cell functions investigated in this study were retained or promoted. Compared to a microtopography, the enhancement of multiple cell functions observed from the hierarchical micro/nano-textured surfaces is expected to lead to faster bone maturation around the titanium implants without compromising the bone mass. In addition, the hierarchical micro/nano-textured surfaces still retain the mechanical interlocking ability of the microtopography thereby boding well for osseointegration. Our study reveals a synergistic role played by the micro and nanotopographies in osteoblast functions and provides insight to the design of better biomedical implant surfaces.

  14. 微纳分级结构碳酸钙中空微球的可控制备%Controllable Fabrication of Calcium Carbonate Hollow Microspheres with Micro-nano Hierarchical Structure

    Institute of Scientific and Technical Information of China (English)

    邹俭鹏; 杨洪志; 肖平; 潘一峰

    2016-01-01

    以CaCl2和Na2CO3为反应原料,以聚乙烯吡咯烷酮(PVP)和十二烷基磺酸钠(SDSN)为模板剂,在50℃采用化学沉淀反应,干燥、煅烧后成功制备了具有微纳分级结构的 CaCO3中空微球。采用扫描电子显微镜、透射电子显微镜和X射线衍射等检测手段对所制备的样品形貌、结构进行了表征,结果显示:所制备的微纳分级结构CaCO3中空微球直径为4~6μm,壳壁由直径约60 nm的CaCO3颗粒组成,壳层厚度约为200 nm, CaCO3中空微球晶相组成为方解石和球霰石的共混体。同时,在反应温度为50℃、PVP添加量为0.4 g, SDSN浓度为0.1 mol/L的条件下,所制备的微纳分级结构CaCO3中空微球分散性好,且形貌比较完整。%With polyvinyl pyrrolidone (PVP) and sodium dodecyl sulfonate (SDSN) as the template, calcium car-bonate hollow microspheres with micro-nano hierarchical structure were successfully synthesized using sodium carbonate and calcium chloride as starting materials through a precipitation reaction method at reaction temperature of 50℃. The products were characterized by scanning electronic microscopy (SEM), transmission electron micro-scope (TEM), X-ray diffraction (XRD) and other detection methods. The results show that the hollow calcium car-bonate microspheres with micro-nano hierarchical structure are about 4-6μm in diameter. The shell thickness of calcium carbonate hollow microspheres is about 200 nm, which consists of calcium carbonate particles with size about 60 nm. The phase of calcium carbonate hollow microspheres is composed of calcite and vaterite. Excellent dispersibility and spherical morphology of calcium carbonate hollow microspheres can be achieved with addition of 0.1 mol/L SDSN and 0.4 g PVP consequently.

  15. Drag reduction in ultrahydrophobic channels with micro-nano structured surfaces

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of experiments have been performed to demonstrate the significant drag reduction of the laminar flow in the ultrahydrophobic channels with dual-scale micro-nano structured surfaces.However,in previous experiments,the ultrahydrophobic surfaces were fabricated with micro-structures or nano-structures and the channels were on the microscale.For the drag reduction in macro-scale channels few reports are available.Here a new method was developed to fabricate ultrahydrophobic surfaces with micro-nano hierarchical structures made from carbon nanotubes.The drag reductions up to 36.3% were observed in the macro-channels with ultrahydrophobic surfaces.The micro-PIV was used to measure the flow velocity in channels.Compared with the traditional no-slip theory at walls,a significant slip velocity was observed on the ultrahydrophobic surfaces.

  16. Adsorption of phenol from aqueous solution by a hierarchical micro-nano porous carbon material

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. Nitrogen adsorption and mercury porosimetry show that mixed nanopores and micropores coexist in MNC with a high specific surface area of 1978 m2·g-1 and a total pore volume of 0.99 cm3·g-1. In addition, the MNC is found to consist of EG and activated carbon with...

  17. Hierarchical Micro/Nano-Porous Acupuncture Needles Offering Enhanced Therapeutic Properties

    Science.gov (United States)

    in, Su-Ll; Gwak, Young S.; Kim, Hye Rim; Razzaq, Abdul; Lee, Kyeong-Seok; Kim, Hee Young; Chang, Suchan; Lee, Bong Hyo; Grimes, Craig A.; Yang, Chae Ha

    2016-10-01

    Acupuncture as a therapeutic intervention has been widely used for treatment of many pathophysiological disorders. For achieving improved therapeutic effects, relatively thick acupuncture needles have been frequently used in clinical practice with, in turn, enhanced stimulation intensity. However due to the discomforting nature of the larger-diameter acupuncture needles there is considerable interest in developing advanced acupuncture therapeutical techniques that provide more comfort with improved efficacy. So motivated, we have developed a new class of acupuncture needles, porous acupuncture needles (PANs) with hierarchical micro/nano-scale conical pores upon the surface, fabricated via a simple and well known electrochemical process, with surface area approximately 20 times greater than conventional acupuncture needles. The performance of these high-surface-area PANs is evaluated by monitoring the electrophysiological and behavioral responses from the in vivo stimulation of Shenmen (HT7) points in Wistar rats, showing PANs to be more effective in controlling electrophysiological and behavioral responses than conventional acupuncture needles. Comparative analysis of cocaine induced locomotor activity using PANs and thick acupuncture needles shows enhanced performance of PANs with significantly less pain sensation. Our work offers a unique pathway for achieving a comfortable and improved acupuncture therapeutic effect.

  18. Cellulose and collagen derived micro-nano structured scaffolds for bone tissue engineering.

    Science.gov (United States)

    Aravamudhan, Aja; Ramos, Daisy M; Nip, Jonathan; Harmon, Matthew D; James, Roshan; Deng, Meng; Laurencin, Cato T; Yu, Xiaojun; Kumbar, Sangamesh G

    2013-04-01

    Scaffold based bone tissue engineering (BTE) has made great progress in regenerating lost bone tissue. Materials of natural and synthetic origin have been used for scaffold fabrication. Scaffolds derived from natural polymers offer greater bioactivity and biocompatibility with mammalian tissues to favor tissue healing, due to their similarity to native extracellular matrix (ECM) components. Often it is a challenge to fabricate natural polymer based scaffolds for BTE applications without compromising their bioactivity, while maintaining adequate mechanical properties. In this work, we report the fabrication and characterization of cellulose and collagen based micro-nano structured scaffolds using human osteoblasts (HOB) for BTE applications. These porous micro-nano structured scaffolds (average pore diameter 190 +/- 10 microm) exhibited mechanical properties in the mid range of human trabecular bone (compressive modulus 266.75 +/- 33.22 MPa and strength 12.15 3 +/- 2.23 MPa). These scaffolds supported the greater adhesion and phenotype maintenance of cultured HOB as reflected by higher levels of osteogenic enzyme alkaline phosphatase and mineral deposition compared to control polyester micro-nano structured scaffolds of identical pore properties. These natural polymer based micro-nano structured scaffolds may serve as alternatives to polyester based scaffolds for BTE applications.

  19. Condensation and Wetting Dynamics on Micro/Nano-Structured Surfaces

    Science.gov (United States)

    Olceroglu, Emre

    Because of their adjustable wetting characteristics, micro/nanostructured surfaces are attractive for the enhancement of phase-change heat transfer where liquid-solid-vapor interactions are important. Condensation, evaporation, and boiling processes are traditionally used in a variety of applications including water harvesting, desalination, industrial power generation, HVAC, and thermal management systems. Although they have been studied by numerous researchers, there is currently a lack of understanding of the underlying mechanisms by which structured surfaces improve heat transfer during phase-change. This PhD dissertation focuses on condensation onto engineered surfaces including fabrication aspect, the physics of phase-change, and the operational limitations of engineered surfaces. While superhydrophobic condensation has been shown to produce high heat transfer rates, several critical issues remain in the field. These include surface manufacturability, heat transfer coefficient measurement limitations at low heat fluxes, failure due to surface flooding at high supersaturations, insufficient modeling of droplet growth rates, and the inherent issues associated with maintenance of non-wetted surface structures. Each of these issues is investigated in this thesis, leading to several contributions to the field of condensation on engineered surfaces. A variety of engineered surfaces have been fabricated and characterized, including nanostructured and hierarchically-structured superhydrophobic surfaces. The Tobacco mosaic virus (TMV) is used here as a biological template for the fabrication of nickel nanostructures, which are subsequently functionalized to achieve superhydrophobicity. This technique is simple and sustainable, and requires no applied heat or external power, thus making it easily extendable to a variety of common heat transfer materials and complex geometries. To measure heat transfer rates during superhydrophobic condensation in the presence of non

  20. Direct writing of large-area micro/nano-structural arrays on single crystalline germanium substrates using femtosecond lasers

    Science.gov (United States)

    Li, Lin; Wang, Jun

    2017-06-01

    A direct writing technique for fabricating micro/nano-structural arrays without using a multi-scanning process, multi-beam interference, or any assisted microlens arrays is reported. Various sub-wavelength micro/nano-structural arrays have been directly written on single crystalline germanium substrate surfaces using femtosecond laser pulses. The evolution of the multiscale surface morphology from periodic micro/nano-structures to V-shaped microgrooves has been achieved, and the relationship between array characteristics and laser polarization directions has been discussed. The self-organization model agrees well with the experimental results in this study.

  1. Fabrication of various micro/nano structures by modified near-field electrospinning

    Directory of Open Access Journals (Sweden)

    T. P. Lei

    2015-04-01

    Full Text Available The modified near-field electrospinning (NFES and the conventional NFES have been compared to demonstrate the viability of direct-writing micro/nano structures from PVDF solution systems. The modified NFES shows good capability in writing various orderly micro/nano patterns, such as straight and continuous lines, parallel lines, arc lines, and beads-on-string structures, whereas the conventional NFES is difficult to give a continuous writing process. Besides, the modified NFES also allows a lower electric field due to the jet initiated in a mechanical way. By finely tuning the key parameters during the modified NFES process, such as the solution property, speed of the movable collector, and the distance between the spinneret and the collector, it is likely to construct complex patterns as required on rigid or flexible substrates for a myriad of applications.

  2. Combining a micro/nano-hierarchical scaffold with cell-printing of myoblasts induces cell alignment and differentiation favorable to skeletal muscle tissue regeneration.

    Science.gov (United States)

    Yeo, Miji; Lee, Hyeongjin; Kim, Geun Hyung

    2016-09-16

    Biomedical scaffolds must be used in tissue engineering to provide physical stability and topological/biochemical properties that directly affect tissue regeneration. In this study, a new cell-laden scaffold was developed that supplies micro/nano-topological cues and promotes efficient release of cells. The hierarchical structure consisted of poly(ε-caprolactone) macrosized struts for sustaining a three-dimensional structural shape, aligned nanofibers obtained with optimized electrospinning, and cell-printed myoblasts. Importantly, the printed myoblasts were fully safe and were efficiently released from the cell-laden struts to neighboring nanofiber networks. The incorporation of micro/nanofibers in the hierarchical scaffold significantly affected myoblast proliferation, alignment, and even facilitated the formation of myotubes. We observed that myosin heavy chain expression and the expression levels of various myogenic genes (MyoD, myogenin, and troponin T) were significantly affected by the fiber alignment achieved in our hierarchical cell-laden structure. We believe that the combination of cell-printing and a hierarchical scaffold that encourages fiber alignment is a highly promising technique for skeletal muscle tissue engineering.

  3. Controllable Direct-Writing of Serpentine Micro/Nano Structures via Low Voltage Electrospinning

    OpenAIRE

    Feiyu Fang; Xin Chen; Zefeng Du; Ziming Zhu; Xindu Chen; Han Wang; Peixuan Wu

    2015-01-01

    Micro/nanofibers prepared by direct-writing using an electrospinning (ES) technique have drawn more attention recently owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW) process was developed to directly write serpentine micro/nano structures suitable for the fabrication of micro devices. This fabrication ability will realize the application of electrospun-nanofiber-based wiring of structu...

  4. Transparent, self-cleaning and waterproof surfaces with tunable micro/nano dual-scale structures

    Science.gov (United States)

    Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

    2016-09-01

    The rational design and facile fabrication of optically transparent, superhydrophobic surfaces can advance their versatile applications, including optoelectronic devices. For the easily accessible and scalable preparation of transparent, superhydrophobic surfaces, various coating methods using a solution-process have been developed. However, obtaining highly transparent, non-wetting surfaces with excellent properties is challenging due to the difficulty in controlling surface roughness. Here, we report on a novel approach to control the surface roughness by fabricating tailorable micro/nano dual-scale surface structures via solution-processed nanoparticle coating. The surface roughness was able to be controlled by micro/nano dual-scale structures that can be manipulated by varying the mixture ratio of two different sizes of Al2O3 nanoparticles. The controllable micro/nano dual-scale structures were optimized to achieve the superior surface properties in both hydrophobicity and transparency, exhibiting a high water contact angle (>160°), low sliding angle (90%). These characteristics allowed an excellent transparency and self-cleaning capability as well as a superior waterproof ability even under applied voltage. Furthermore, we demonstrated the versatile applicability of the developed surface-coating method to a wide range of substrates including glass, paper, fabrics, and even flexible plastics.

  5. Bio-Inspired Design and Fabrication of Micro/Nano-Brush Dual Structural Surfaces for Switchable Oil Adhesion and Antifouling.

    Science.gov (United States)

    Du, Tao; Ma, Shuanhong; Pei, Xiaowei; Wang, Shutao; Zhou, Feng

    2017-01-01

    The underwater superoleophobic surfaces play a significant role in anti-oil contamination, marine antifouling, etc. Inspired by the Gecko's feet and its self-cleaning property, a hierarchical structure composed of poly (acrylic acid) gel micro-brushes is designed by the liquid-infused method. This surface exhibits underwater superoleophobicity with very low oil adhesion. It is then modified with stimuli-responsive polymer nano-brushes via surface-initiated atom transfer radical polymerization from the embedded initiator. The micro/nano-brush dual structural surfaces can switch the underwater oil adhesion between low and high while keeping the superoleophobicity. The antifouling properties against algae attachment under different mediums are also investigated to show a strong link between oleophobicity and antibiofouling property. The model surface will be very useful in directing the design of marine self-cleaning coatings to both living and non-living species.

  6. Determination of standard molar enthalpies of formation of SrMoO{sub 4} micro/nano structures

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yunxiao; Fan, Gaochao [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China); Huang, Zaiyin, E-mail: huangzaiyin@163.com [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China); Sun, Jilong; Wang, Lude; Wang, Tenghui; Chen, Jie [College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning 530006 (China)

    2012-02-20

    Graphical abstract: Schematic illustration of thermochemical cycle between the nano and bulk reaction systems. Highlights: Black-Right-Pointing-Pointer A thermochemical cycle was designed. Black-Right-Pointing-Pointer Relationship of standard molar enthalpies of formation between micro/nano and bulk SrMoO{sub 4} was gained. Black-Right-Pointing-Pointer Microcalorimetry was used as a supplementary technology. Black-Right-Pointing-Pointer Standard molar enthalpies of formation of the synthesized micro/nano SrMoO{sub 4} were obtained. Black-Right-Pointing-Pointer This novel approach can be used to other micro/nano materials. - Abstract: SrMoO{sub 4} micro/nano structures were prepared by a simple reverse microemulsion method and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope (SEM). In order to associate standard molar enthalpies of formation of nano SrMoO{sub 4} with bulk SrMoO{sub 4}, the relationship of them was obtained through designing a thermochemical cycle according to thermodynamic potential function method. Combined with microcalorimetry, the standard molar enthalpies of formation of the synthesized micro/nano SrMoO{sub 4} at 298.15 K were gained in this paper. And the variation of standard molar enthalpies of formation of micro/nano SrMoO{sub 4} with different morphologies and sizes was discussed.

  7. Fabrication and characterization of micro- /nano structures for nanophotonic applications

    Science.gov (United States)

    Jee, Hongsub

    The objective of this thesis is finding and developing fabrication methods to provide background techniques for potential applications with nanomaterials. The inclined UV lithography has announced to make three-dimensional fabrication process. With a movable stage, complex structures were achieved but difference of the refractive index, design of the final structures were limited. Refractive index matching medium between the substrate and the light source could reduce the refractive indices between the polymer and the substrate successfully. Nanoporous structures fabricated by multibeam interference lithography shows limitation of the usage since its periodicity. By insertion of the lift off resist layer between the patterned layer and the substrate, final photonic crystal structures could be partially removed for its own purpose and it provide potential application in the future. Two-step processing, combining with reactive ion etching system, nanoporous structures were on various substrates such as silicon and Polydimethylsiloxane. Photonic crystal template anodic aluminum oxide process has been described too. Large optical activity at visible wavelengths are of great attention in photonics. Dramatic enhancement of the optical activity of chiral poly(fluorene-alt-benzothiadiazole) with photoresist was demonstrated and successive photo patterning of chiral polymer shows the potential usage of this material for the photonics applications. Two photon lithography also used to pattern a photoresist-chiral polymer mixture into planar shapes and enhanced chirality can be realized by tuning the wavelength-dependent chiral response at both the molecular and geometric level. Near infrared light induced photopolymerization in-situ was demonstrated which can be applied everywhere where ultraviolet-polymerization is employed such as dentistry, coating industry. Use of the ultraviolet upconverting nanoparticles doped into the polymer, we show that expensive femtosecond pulsed

  8. Controllable Direct-Writing of Serpentine Micro/Nano Structures via Low Voltage Electrospinning

    Directory of Open Access Journals (Sweden)

    Feiyu Fang

    2015-08-01

    Full Text Available Micro/nanofibers prepared by direct-writing using an electrospinning (ES technique have drawn more attention recently owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW process was developed to directly write serpentine micro/nano structures suitable for the fabrication of micro devices. This fabrication ability will realize the application of electrospun-nanofiber-based wiring of structural and functional components in microelectronics, MEMS, sensor, and micro optoelectronics devices, and, especially, paves the way for the application of electrospinning in printing serpentine interconnector of large-area organic stretchable electronics.

  9. Optical properties of the micro/nano structures of Morpho butterfly wing scales

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The micro/nano structures of the wing scales in Morpho butterfly are responsible for the structural coloration,with a major part ascribed to interference and diffraction of light.The optical properties of the butterfly wings were investigated by simulating a two-dimensional model using rigorous coupled-wave analysis technique.It is proved that they depend strongly on the structural parameters,incidence angle and refractive index.The peak value and the peak wavelength of the reflection efficiency increase as the vertical periodic thickness increases.The peak value decreases observably,while both of the bandwidth and the peak wavelength increase when the number of the vertical periods decreases.Increase of the horizontal periodic width causes a decrease of the peak value and an increase of the peak wavelength,although the variations are small.The peak value decreases distinctly and the peak wavelength increases as the ambient refractive index increases,which corresponds to the variation in ambient conditions.The research reveals the mechanisms of the brilliant structural color in Morpho butterfly,and is of great significance to the design,manufacture and applications of the bionic micro/nano structures for gas detection.

  10. Micro/Nano-Structured Flexible Foils for Anti-Counterfeiting Purposes

    DEFF Research Database (Denmark)

    Okulova, Nastasia

    2016-01-01

    Up to date there have been found many ways of producing samples with functional nano-pattering, however for mass production of such samples the method of fabrication of the surface structure must be fast and cheap. A recently developed method suggests using extrusion coating of polymer materials...... in a roll-to roll process, where the functional micro-/nano- surface structures are imprinted directly onto the surface of a polymer foil. This new technology can both answer the requirement for being fast and cheap. The aim of this project is implementation of the technology for mass production...... has been demonstrated. The focus of this study lies on the reproduction of the previous results for nano- or micro-structures and implementation of this technology for mass production of such patterned foils for the use in packaging. An interesting application is production of holograms with build...

  11. Facile Fabrication of Micro-Nano Structured Triboelectric Nanogenerator with High Electric Output

    Science.gov (United States)

    Zhang, Feifei; Li, Baozhang; Zheng, Jianming; Xu, Chunye

    2015-07-01

    In this article, a new method is used to fabricate a high-performance triboelectric nanogenerator (TENG), which is convenient and cost-effective. A polyformaldehyde (POM) film with novel structures is prepared through electrospinning and is combined with a polytetrafluoroethylene (PTFE) film to assemble micro-nano structured TENG. The short-circuit current ( I s) and open-circuit voltage ( V o) of the TENG are up to 0.4343 mA and 236.8 V, respectively, and no significant change is observed by applying different frequencies of external impact forces from 1 to 10 Hz. Finally, we successfully drive an electrochromic device (ECD) directly using TENG within just 2 min for the first time.

  12. Hybrid micro-/nano-structures derived from metal-organic frameworks: preparation and applications in energy storage and conversion.

    Science.gov (United States)

    Cao, Xiehong; Tan, Chaoliang; Sindoro, Melinda; Zhang, Hua

    2017-05-22

    Metal-organic frameworks (MOFs), an important class of inorganic-organic hybrid crystals with intrinsic porous structures, can be used as versatile precursors or sacrificial templates for preparation of numerous functional nanomaterials for various applications. Recent developments of MOF-derived hybrid micro-/nano-structures, constructed by more than two components with varied functionalities, have revealed their extensive capabilities to overcome the weaknesses of the individual counterparts and thus give enhanced performance for energy storage and conversion. In this tutorial review, we summarize the recent advances in MOF-derived hybrid micro-/nano-structures. The synthetic strategies for preparing MOF-derived hybrid micro-/nano-structures are first introduced. Focusing on energy storage and conversion, we then discuss their potential applications in lithium-ion batteries, lithium-sulfur batteries, supercapacitors, lithium-oxygen batteries and fuel cells. Finally, we give our personal insights into the challenges and opportunities for the future research of MOF-derived hybrid micro-/nano-structures.

  13. Fabrication of Micro/Nano Structures on Metals by Femtosecond Laser Micromachining

    Directory of Open Access Journals (Sweden)

    K. M. Tanvir Ahmmed

    2014-11-01

    Full Text Available Femtosecond laser micromachining has emerged in recent years as a new technique for micro/nano structure fabrication because of its applicability to virtually all kinds of materials in an easy one-step process that is scalable. In the past, much research on femtosecond laser micromachining was carried out to understand the complex ablation mechanism, whereas recent works are mostly concerned with the fabrication of surface structures because of their numerous possible applications. The state-of-the-art knowledge on the fabrication of these structures on metals with direct femtosecond laser micromachining is reviewed in this article. The effect of various parameters, such as fluence, number of pulses, laser beam polarization, wavelength, incident angle, scan velocity, number of scans, and environment, on the formation of different structures is discussed in detail wherever possible. Furthermore, a guideline for surface structures optimization is provided. The authors’ experimental work on laser-inscribed regular pattern fabrication is presented to give a complete picture of micromachining processes. Finally, possible applications of laser-machined surface structures in different fields are briefly reviewed.

  14. Determination of reactive oxygen species from ZnO micro-nano structures with shape-dependent photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    He, Weiwei; Zhao, Hongxiao; Jia, Huimin [Key Laboratory of Micro-Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, Xuchang University, Henan 461000 (China); Yin, Jun-Jie [Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD 20740 (United States); Zheng, Zhi, E-mail: zhengzhi99999@gmail.com [Key Laboratory of Micro-Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, Xuchang University, Henan 461000 (China)

    2014-05-01

    Graphical abstract: ZnO micro/nano structures with shape dependent photocatalytic activity were prepared by hydrothermal reaction. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were identified precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO. - Highlights: • ZnO micro/nano structures with different morphologies were prepared by solvothermal reaction. • Multi-pod like ZnO structures exhibited superior photocatalytic activity. • The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were characterized precisely by electron spin resonance spectroscopy. • The type of reactive oxygen species was determined by band gap structure of ZnO. - Abstract: ZnO micro/nano structures with different morphologies have been prepared by the changing solvents used during their synthesis by solvothermal reaction. Three typical shapes of ZnO structures including hexagonal, bell bottom like and multi-pod formed and were characterized by scanning electron microscopy and X-ray diffraction. Multi pod like ZnO structures exhibited the highest photocatalytic activity toward degradation of methyl orange. Using electron spin resonance spectroscopy coupled with spin trapping techniques, we demonstrate an effective way to identify precisely the generation of hydroxyl radicals, superoxide and singlet oxygen from the irradiated ZnO multi pod structures. The type of reactive oxygen species formed was predictable from the band gap structure of ZnO. These results indicate that the shape of micro-nano structures significantly affects the photocatalytic activity of ZnO, and demonstrate the value of electron spin resonance spectroscopy for characterizing the type of reactive oxygen species formed during photoexcitation of semiconductors.

  15. Virostatic potential of micro-nano filopodia-like ZnO structures against herpes simplex virus-1

    OpenAIRE

    Mishra, Yogendra Kumar; Adelung, Rainer; Roehl, Claudia; Shukla, Deepak; Spors, Frank; Tiwari, Vaibhav

    2011-01-01

    Herpes simplex virus type-1 (HSV-1) entry into target cell is initiated by the ionic interactions between positively charged viral envelop glycoproteins and a negatively charged cell surface heparan sulfate (HS). This first step involves the induction of HS-rich filopodia-like structures on the cell surface that facilitate viral transport during cell entry. Targeting this initial first step in HSV-1 pathogenesis, we generated different zinc oxide (ZnO) micro-nano structures (MNSs) that were c...

  16. Ultrafast Laser Pulses for Structuring Materials at Micro/Nano Scale: From Waveguides to Superhydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Daniel S. Correa

    2017-01-01

    Full Text Available The current demand for fabricating optical and photonic devices displaying high performance, using low-cost and time-saving methods, prompts femtosecond (fs-laser processing as a promising methodology. High and low repetition femtosecond lasers enable surface and/or bulk modification of distinct materials, which can be used for applications ranging from optical waveguides to superhydrophobic surfaces. Herein, some fundamental aspects of fs-laser processing of materials, as well as the basics of their most common experimental apparatuses, are introduced. A survey of results on polymer fs-laser processing, resulting in 3D waveguides, electroluminescent structures and active hybrid-microstructures for luminescence or biological microenvironments is presented. Similarly, results of fs-laser processing on glasses, gold and silicon to produce waveguides containing metallic nanoparticles, analytical chemical sensors and surface with modified features, respectively, are also described. The complexity of fs-laser micromachining involves precise control of material properties, pushing ultrafast laser processing as an advanced technique for micro/nano devices.

  17. [Study of the Raman-AFM system for simultaneous measurements of Raman spectrum and micro/nano-structures].

    Science.gov (United States)

    Shi, Bin; Zhang, Hai-jun; Wu, Lan; Zhang, Dong-xian

    2012-04-01

    This paper proposes a novel technique of Raman-atomic force microscopy (AFM) combining micro region Raman spectroscopy and AFM imaging. An in-situ probe unit which can simultaneously realize the detection of Raman spectrum and the measurement of AFM image was designed, and a related Raman-AFM system was constructed. Using this system, some experiments were carried out to acquire micro region Raman spectra and AFM images of ZnO nano-particle and TiO2 film. The results show that the Raman spectra of both samples are in agreement with theoretical vaues, and the AFM images represent their micro/nano-structures quite well. These researches prove the feasibility of the Raman-AFM technique which has the potential of being widely applied in the fields of Raman spectroscopy and micro/nano-technology.

  18. Rapid fabrication of surface micro/nano structures with enhanced broadband absorption on Cu by picosecond laser.

    Science.gov (United States)

    Fan, Peixun; Zhong, Minlin; Li, Lin; Huang, Ting; Zhang, Hongjun

    2013-05-20

    A surface micro/nano structuring technique was demonstrated by utilizing a picosecond laser beam to rapidly modify the optical property of copper surfaces with a scanning speed up to tens of millimeters per second. Three kinds of surface micro/nanostructures corresponding to three levels of reflectance were produced which are obviously different from those induced by a femtosecond or nanosecond laser. Specifically, a porous coral-like structure results in over 97% absorptivity in the visible spectral region and over 90% absorptivity in average in the UV, visible, and NIR regions (250 - 2500 nm). Potential applications may include solar energy absorbers, thermal radiation sources, and radiative heat transfer devices.

  19. Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing.

    Science.gov (United States)

    Huan, Z; Fratila-Apachitei, L E; Apachitei, I; Duszczyk, J

    2014-02-07

    The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

  20. Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing

    Science.gov (United States)

    Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

    2014-02-01

    The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

  1. Hybrid micro/nano-structure formation by angular laser texturing of Si surface for surface enhanced Raman scattering.

    Science.gov (United States)

    Xu, Kaichen; Zhang, Chentao; Zhou, Rui; Ji, Rong; Hong, Minghui

    2016-05-16

    Surface enhanced Raman spectroscopy (SERS) has drawn much research interest in the past decades as an efficient technique to detect low-concentration molecules. Among many technologies, which can be used to fabricate SERS substrates, laser ablation is a simple and high-speed method to produce large-area SERS substrates. This work investigates the angular texturing effect by dynamic laser ablation and its influence on SERS signals. By tuning the angle between the Si surface and laser irradiation, the distributions and sizes of laser induced hybrid micro/nano-structures are studied. By decorating with a silver film, plenty of hot spots can be created among these structures for SERS. It is found that when the incident laser angle is 15° at the laser fluence of 16.0 J/cm2, the SERS performance is well optimized. This work realizes antisymmetric distribution of nanoparticles deposited on Si surface, which provides a flexible tuning of the hybrid micro/nano-structures' fabrication with high controllability for practical applications.

  2. Fabrication of polyimide micro/nano-structures based on contact-transfer and mask-embedded lithography

    Science.gov (United States)

    Chiu, Cheng-Yu; Lee, Yung-Chun

    2009-10-01

    Polyimide materials are well known for their excellent mechanical and chemical stability which, as an adverse consequence, makes their fabrication processes much more difficult, especially in micro- and nano-scales. In this paper, we demonstrate an innovative and powerful method for fabricating micro/nano-structures on polyimides. The proposed method first adopts an imprinting approach to transfer a patterned metal film from a mold to a polymer layer coated on a polyimide layer. The patterned double polymer layers are then dry etched using the transferred metal pattern as an etching mask. Finally, polyimide structures are obtained by lifting off the top polymer layer and the metal film through wet etching. Experiments have been carried out and important parameters to achieve high pattern-transformation fidelity are determined. Fine structures of polyimides with a feature size of 500 nm and a total patterned area of 8 × 8 mm2 are demonstrated. Advantages of the proposed method include low-temperature, low contact pressure, small feature size, high throughput and ease of in implementation. Most importantly, it is applicable for a large number of tough polymers which are difficult to deal with by other methods in terms of micro/nano-fabrication.

  3. Bio-inspired micro-nano structured surface with structural color and anisotropic wettability on Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yan [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130022 (China); Li, Shuyi; Niu, Shichao [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); Cao, Xiaowen [Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Han, Zhiwu, E-mail: zwhan@jlu.edu.cn [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China); Ren, Luquan [Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Changchun 130022 (China)

    2016-08-30

    Highlights: • We have prepared a biomimetic hydrophobic surface on copper substrate by one-step femtosecond laser technique. • The hydrophobicity mechanism relies on morphology and chemical component on surface. • The hydrophobic surfaces exhibit different structural colors and a anisotropic wettability. - Abstract: Inspired by the unique creatures in the nature, the femtosecond laser technology has been usually used to fabricate the periodic microstructures due to its advantages of rapidness, simplicity, ease of large-area fabrication, and simultaneously offering dual micro/nano-scale structures simply via one-step process for a wide variety of materials. By changing the experimental conditions, multi-functional surfaces which possess superhydrophobicity and structural colors could be achieved on copper substrate. In addition, the apparent contact angle can reach 144.3° without any further modification, which also exhibits the anisotropic wettability. Moreover, it can be inferred that higher laser fluence can lead to a larger CA within a certain range. At the same time, due to the change of laser processing parameters, the obtained surfaces present different structural colors. This study may expand the applications of bio-inspired functional materials because multiple colors and hydrophobicity are both important features in the real life and industrial applications, such as display, decoration, and anti-counterfeiting technology etc.

  4. Bio-inspired micro-nano structured surface with structural color and anisotropic wettability on Cu substrate

    Science.gov (United States)

    Liu, Yan; Li, Shuyi; Niu, Shichao; Cao, Xiaowen; Han, Zhiwu; Ren, Luquan

    2016-08-01

    Inspired by the unique creatures in the nature, the femtosecond laser technology has been usually used to fabricate the periodic microstructures due to its advantages of rapidness, simplicity, ease of large-area fabrication, and simultaneously offering dual micro/nano-scale structures simply via one-step process for a wide variety of materials. By changing the experimental conditions, multi-functional surfaces which possess superhydrophobicity and structural colors could be achieved on copper substrate. In addition, the apparent contact angle can reach 144.3° without any further modification, which also exhibits the anisotropic wettability. Moreover, it can be inferred that higher laser fluence can lead to a larger CA within a certain range. At the same time, due to the change of laser processing parameters, the obtained surfaces present different structural colors. This study may expand the applications of bio-inspired functional materials because multiple colors and hydrophobicity are both important features in the real life and industrial applications, such as display, decoration, and anti-counterfeiting technology etc.

  5. Super-hydrophobic and oleophobic transparent surfaces using micro-nano-structuring techniques

    OpenAIRE

    Von Rudno, Markus

    2015-01-01

    Treball fet en col·laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB) i Institut de Ciències Fotòniques (ICFO) In this thesis we describe the successful design and fabrication of three distinct high-order hierarchical structures based on silica to invoke super-hydrophobicity and oleophobicity on optically transparent surfaces, which may find application in display screens, solar cell panels and smart windows. These include directly synthesized and highly ...

  6. Long time and distance self-propelling of a PVC sphere on a water surface with an embedded ZnO micro-/nano-structured hollow sphere.

    Science.gov (United States)

    Wang, Lei; Yu, Lujia; Yi, Liting; Yuan, Bin; Hou, Yongping; Meng, Xiangfu; Liu, Jing

    2017-02-16

    In this research, a zinc oxide micro-/nano-structured hollow sphere (MNHS) with a large specific surface area is applied as energy storage material to encapsulate poly(vinyl chloride) solution and control the fuel release. The sustained release effect of MNHS not only makes the motion more controllable, but enhances the motion time and distance.

  7. Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

    Science.gov (United States)

    Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

    2013-03-01

    The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  8. Multiscale Micro-Nano Nested Structures: Engineered Surface Morphology for Efficient Light Escaping in Organic Light-Emitting Diodes.

    Science.gov (United States)

    Zhou, Lei; Dong, Xiaoxuan; Zhou, Yun; Su, Wenming; Chen, Xiaolian; Zhu, Yufu; Shen, Su

    2015-12-01

    Various micro-to-nanometer scale structures are extremely attractive for light escaping in organic light-emitting diodes. To develop and optimize such structures, an innovative approach was demonstrated for the first time to fabricate multiscale micro-nano nested structures by photolithography with a well-designed mask pattern followed by a controllable thermal reflow process. The experimental and theoretical characterizations verify that these unique nested structures hold the capability of light concentration, noticeable low haze, and efficient antireflection. As a proof-of-concept, the incorporation of this pattern onto the glass substrate efficiently facilitates light escaping from the device, resulting in current efficiency 1.60 times and external quantum efficiency 1.63 times that of a control flat device, respectively. Moreover, compared to a hexagonally arranged microlens array and quasi-random biomimetic moth eye nanostructures, the nested structures proposed here can magically tune the spatial emission profile to comply with the Lambertian radiation pattern. Hence, this novel structure is expected to be of great potential in related ubiquitous optoelectronic applications and provide scientific inspiration to other novel multiscale micro-nanostructure research.

  9. Comparison of Super-Hydrophobicity and Corrosion Resistance of Micro-Nano Structured Nickel and Nickel- Cobalt Alloy Coatings on Copper Substrate

    Directory of Open Access Journals (Sweden)

    S. Khorsand

    2016-03-01

    Full Text Available Super-hydrophobic nickel and nickel-cobalt alloy coatings with micro-nano structure were successfully electrodeposited on copper substrates with one and two steps electrodeposition. Surface morphology, wettability and corrosion  resistance were characterized by scanning electron microscopy, water contact angle measurements, electrochemical impedanc spectroscopy (EIS and potentiodynamic polarization curves. The results showed that the wettability of the micro-nano Ni and Ni-Co films varied from super-hydrophilicity to super-hydrophobicity by exposure of the surface to air at room temperature. The corrosion results revealed the positive effect of hydrophobicity on corrosion resistance of Ni coating (~10 times and Ni-Co coating (~100 times in comparison with their fresh coatings. The results showed that super-hydrophobic nickel coating had higher corrosion resistance than super-hydrophobic nickel-cobalt coating.

  10. Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

    Science.gov (United States)

    Ye, Zhou; Nain, Amrinder S.; Behkam, Bahareh

    2016-06-01

    Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for

  11. Comparison of 3 methods on fabricating micro- /nano- structured surface on 3D mold cavity

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard; Bissacco, Giuliano

    2015-01-01

    The methods to manufacture micro- or nano- structures on surfaces have been an area of intense investigation. Demands are shown for technologies for surface structuring on real 3D parts in many fields. However, most technologies for the fabrication of micro-structured functional surfaces are stil...

  12. Proton beam writing of long, arbitrary structures for micro/nano photonics and fluidics applications

    Energy Technology Data Exchange (ETDEWEB)

    Udalagama, Chammika, E-mail: chammika@nus.edu.sg [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, Singapore 117542 (Singapore); Teo, E.J. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, Singapore 117542 (Singapore); Chan, S.F. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, Singapore 117542 (Singapore); NUS Nanoscience and Nanotechnology Initiative, 2 Science Drive 3, 117542 (Singapore); Department of Chemistry, NUS, 3 Science Drive 3, 117543 (Singapore); Kumar, V.S.; Bettiol, A.A.; Watt, F. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, Singapore 117542 (Singapore)

    2011-10-15

    The last decade has seen proton beam writing maturing into a versatile lithographic technique able to produce sub-100 nm, high aspect ratio structures with smooth side walls. However, many applications in the fields of photonics and fluidics require the fabrication of structures with high spatial resolution that extends over several centimetres. This cannot be achieved by purely magnetic or electrostatic beam scanning due to the large off-axis beam aberrations in high demagnification systems. As a result, this has limited us to producing long straight structures using a combination of beam and stage scanning. In this work we have: (1) developed an algorithm to include any arbitrary pattern into the writing process by using a more versatile combination of beam and stage scanning while (2) incorporating the use of the ubiquitous AutoCAD DXF (drawing exchange format) into the design process. We demonstrate the capability of this approach in fabricating structures such as Y-splitters, Mach-Zehnder modulators and microfluidic channels that are over several centimetres in length, in polymer. We also present optimisation of such parameters as scanning speed and scanning loops to improve on the surface roughness of the structures. This work opens up new possibilities of using CAD software in PBW for microphotonics and fluidics device fabrication.

  13. Laser surface micro-/nano-structuring by a simple transportable micro-sphere lens array

    NARCIS (Netherlands)

    Sedao, X.; Derrien, T.J.Y.; Romer, G.W.R.B.E.; Pathiraj, B.; Huis in 't Veld, A.J.

    2012-01-01

    A micro-sphere array optic was employed for laser surface micro-structuring. This array optic consists of a hexagonally close-packed monolayer of silica micro-spheres. It was organized through a self-assembly process and held together on a glass support, without using any adhesives. The array assemb

  14. Laser surface micro-/nano-structuring by a simple transportable micro-sphere lens array

    NARCIS (Netherlands)

    Sedao, X.; Derrien, T.J.Y.; Romer, G.W.R.B.E.; Pathiraj, B.; Huis in 't Veld, A.J.

    2012-01-01

    A micro-sphere array optic was employed for laser surface micro-structuring. This array optic consists of a hexagonally close-packed monolayer of silica micro-spheres. It was organized through a self-assembly process and held together on a glass support, without using any adhesives. The array

  15. Controllable synthesis and formation mechanism of carbon micro/nano-structural materials

    Science.gov (United States)

    Zhang, Chang'an; Lv, Meijiao; Wang, Xianbao; Li, Jing; Yang, Xuyu; Yang, Jia; Hu, Hao

    2013-10-01

    Three different structures of carbon materials, including carbon spheres, bamboo-like carbon nanotubes and straight carbon nanotubes, were obtained by pyrolysis of iron(II) phthalocyanine with different flow rates of H2 at 1000 °C. The suitable mechanism for formation process of the carbon nanomaterials from spheres to straight nanotubes was suggested. The competing processes between the catalyst forward and the shell growth have been used to explain the formation mechanism of three materials. The controllable synthesis of carbon materials was achieved only by changing the H2 flow rates, and it is important to explore applications of carbon materials with different shapes.

  16. Arrays of metallic micro-/nano-structures by means of colloidal lithography and laser dewetting

    Science.gov (United States)

    Constantinescu, C.; Deepak, K. L. N.; Delaporte, P.; Utéza, O.; Grojo, D.

    2016-06-01

    Long-range arrays of prismatoid metal nanostructures are fabricated by a hybrid methodology, i.e. using Langmuir microsphere films and laser-assisted dewetting. As the initial step, we use colloidal lithography. Monolayers of 1-5 μm polystyrene microspheres covered with a thermally evaporated Ag or Au thin film of controlled thickness (5-50 nm) are then used as masks to pattern the surface of quartz, BK7 glass or silicon substrates, typically in the order of cm2. When removing the spheres by physico-chemical means (ultrasound bath and solvent wash), the resulting surface shows an array of nm-size prismatoid structures (Fischer patterns), that can be further processed by laser. Thus, by using two different lasers (355-nm wavelength, 50-ps duration and 193-nm wavelength, 15-ns duration) for the metal dewetting, we control the shape of the deposited nanostructures. A detailed study is presented here on the reshaping of such metal structures through laser annealing. This new hybrid methodology expands the panel of microsphere-assisted technologies employed in preparing surface nanomaterials.

  17. Lubricant-infused micro/nano-structured surfaces with tunable dynamic omniphobicity at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, D; Mankin, MN; Belisle, RA; Wong, TS; Aizenberg, J

    2013-06-10

    Omniphobic surfaces that can repel fluids at temperatures higher than 100 degrees C are rare. Most state-of-the-art liquid-repellent materials are based on the lotus effect, where a thin air layer is maintained throughout micro/nanotextures leading to high mobility of liquids. However, such behavior eventually fails at elevated temperatures when the surface tension of test liquids decreases significantly. Here, we demonstrate a class of lubricant-infused structured surfaces that can maintain a robust omniphobic state even for low-surface-tension liquids at temperatures up to at least 200 degrees C. We also demonstrate how liquid mobility on such surfaces can be tuned by a factor of 1000. (C) 2013 Author(s).

  18. Lubricant-infused micro/nano-structured surfaces with tunable dynamic omniphobicity at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Daniel; Max, Mankin N.; Belisle, Rebecca A.; Wong, Tak-Sing; Aizenberg, Joanna

    2013-06-12

    Omniphobic surfaces that can repel fluids at temperatures higher than 100 °C are rare. Most stateof- the-art liquid-repellent materials are based on the lotus effect, where a thin air layer is maintained throughout micro/nanotextures leading to high mobility of liquids. However, such behavior eventually fails at elevated temperatures when the surface tension of test liquids decreases significantly. Here, we demonstrate a class of lubricant-infused structured surfaces that can maintain a robust omniphobic state even for low-surface-tension liquids at temperatures up to at least 200 °C. We also demonstrate how liquid mobility on such surfaces can be tuned by a factor of 1000.

  19. Lubricant-infused micro/nano-structured surfaces with tunable dynamic omniphobicity at high temperatures

    Science.gov (United States)

    Daniel, Daniel; Mankin, Max N.; Belisle, Rebecca A.; Wong, Tak-Sing; Aizenberg, Joanna

    2013-06-01

    Omniphobic surfaces that can repel fluids at temperatures higher than 100 °C are rare. Most state-of-the-art liquid-repellent materials are based on the lotus effect, where a thin air layer is maintained throughout micro/nanotextures leading to high mobility of liquids. However, such behavior eventually fails at elevated temperatures when the surface tension of test liquids decreases significantly. Here, we demonstrate a class of lubricant-infused structured surfaces that can maintain a robust omniphobic state even for low-surface-tension liquids at temperatures up to at least 200 °C. We also demonstrate how liquid mobility on such surfaces can be tuned by a factor of 1000.

  20. Modelling the Size Effects on the Mechanical Properties of Micro/Nano Structures

    Science.gov (United States)

    Abazari, Amir Musa; Safavi, Seyed Mohsen; Rezazadeh, Ghader; Villanueva, Luis Guillermo

    2015-01-01

    Experiments on micro- and nano-mechanical systems (M/NEMS) have shown that their behavior under bending loads departs in many cases from the classical predictions using Euler-Bernoulli theory and Hooke’s law. This anomalous response has usually been seen as a dependence of the material properties on the size of the structure, in particular thickness. A theoretical model that allows for quantitative understanding and prediction of this size effect is important for the design of M/NEMS. In this paper, we summarize and analyze the five theories that can be found in the literature: Grain Boundary Theory (GBT), Surface Stress Theory (SST), Residual Stress Theory (RST), Couple Stress Theory (CST) and Surface Elasticity Theory (SET). By comparing these theories with experimental data we propose a simplified model combination of CST and SET that properly fits all considered cases, therefore delivering a simple (two parameters) model that can be used to predict the mechanical properties at the nanoscale. PMID:26569256

  1. Synthesis, characterization and antimicrobial activity of the micro/nano structured biogenic silver doped calcium phosphate

    Science.gov (United States)

    Supraja, N.; Prasad, T. N. V. K. V.; David, Ernest

    2016-01-01

    Scale formation in PVC pipelines reduces the water flow efficiency and enhances microbial contamination. A bio-based composite material comprising of silver doped calcium phosphate (Cp-Ag) was synthesized using a simple technique (photo catalysis) and herein, we report for the first time on preparation and evaluation of the antimicrobial efficacy of silver doped calcite extracted from the scale in drinking water pipe lines. Five concentrations of silver doped calcite materials viz,5, 10, 15, 20 and 25 ppm were prepared using chemical ammonia mediated synthetic method. The material Cp-Ag was characterized by using the techniques UV-Visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, Raman spectroscopy, Thermo gravimetric analysis, X-ray photo electron spectroscopy (XPS), Nuclear magnetic resonance spectrometer and X-ray flouresence microscopy (XRF). Typical rhombohedral structure of the silver doped calcite was observed. XRF and XPS studies confirmed the presence of both calcium and silver in the composite material (Cp-Ag). The silver doped calcite material exhibited enhanced inhibition against Escherichia coli and staphylococcus aureus (Kirby-Bauer discs diffusion assay) which is also dependent on the concentration of the Cp-Ag material.

  2. Bioinspired micro/nano fabrication on dental implant-bone interface

    Science.gov (United States)

    Wang, Feng; Shi, Liang; He, Wen-Xi; Han, Dong; Yan, Yan; Niu, Zhong-Ying; Shi, Sheng-Gen

    2013-01-01

    Pioneering research suggests fabricating a biomimetic interface with multiscaled surfacial architecture can greatly improve biomaterials' function and property. According to this inspiration, we chiefly single out and analyze the natural hierarchical micro/nano structure in rat's alveolar bone. Then, a combined hierarchical structure, i.e. micro-pits interlaced self-assemble TiO2 nanotubes of several tens of nanometers on dental implant's surface is developed. The as-prepared surface showed that hundreds of self-assembled TiO2 nanotubes were tightly arrayed with a diameter range of 30-50 nm, similar to collagen fibers within rat's mandible (60-80 nm). Meanwhile, this hierarchical micro/nano surface can provide a larger surface energy and roughness, a preferable hydrophilicity, a more adaptive mechanical property and adhesion work, a better bioactivity and biocompatibity, a superior attachment and growth of osteoblasts as compared to the smooth and purely micro-treated counterparts. The results indicated that this bioinspired micro/nano fabrication on dental implant-bone interface can be potentially applied in the update of dental implant in patients' clinical therapy and provide a new strategy for fabricating other osteocompatible materials.

  3. Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation.

    Science.gov (United States)

    Xu, Jia-Yun; Chen, Xian-Shuai; Zhang, Chun-Yu; Liu, Yun; Wang, Jing; Deng, Fei-Long

    2016-11-01

    Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P<0.05) and higher total protein contents on the 14th day (P<0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P<0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes.

  4. Electrochemical micro/nano-machining: principles and practices.

    Science.gov (United States)

    Zhan, Dongping; Han, Lianhuan; Zhang, Jie; He, Quanfeng; Tian, Zhao-Wu; Tian, Zhong-Qun

    2017-03-06

    Micro/nano-machining (MNM) is becoming the cutting-edge of high-tech manufacturing because of the increasing industrial demand for supersmooth surfaces and functional three-dimensional micro/nano-structures (3D-MNS) in ultra-large scale integrated circuits, microelectromechanical systems, miniaturized total analysis systems, precision optics, and so on. Taking advantage of no tool wear, no surface stress, environmental friendliness, simple operation, and low cost, electrochemical micro/nano-machining (EC-MNM) has an irreplaceable role in MNM. This comprehensive review presents the state-of-art of EC-MNM techniques for direct writing, surface planarization and polishing, and 3D-MNS fabrications. The key point of EC-MNM is to confine electrochemical reactions at the micro/nano-meter scale. This review will bring together various solutions to "confined reaction" ranging from electrochemical principles through technical characteristics to relevant applications.

  5. One-pot chemical route for morphology-controllable fabrication of Sn-Sb micro/nano-structures: Advanced anode materials for lithium and sodium storage

    Science.gov (United States)

    Yi, Zheng; Han, Qigang; Geng, Di; Wu, Yaoming; Cheng, Yong; Wang, Limin

    2017-02-01

    A series of morphology/component-controllable Sn-Sb micro/nano-structures are fabricated by a one-pot replacement reaction technique employing metallic Sn as both template and reducing agent. Typically, nanoscaled Sn as template and ethyl alcohol as solvent give the hollow structure, while micron-sized Sn as precursor and ethylene glycol as solvent produce the dendritic product. Other mixed structures are also obtained by this one-pot route. As anode materials for lithium-ion batteries, the hollow or dendritic Sn-Sb materials exhibit higher discharge capacities compared with the corresponding Sb samples as well as the Sn templates. Especially, for the Sn-Sb hollow spheres, a high discharge capacity of 820.7 mAh g-1 after first cycle and a reversible capacity of 751 mAh g-1 are achieved after 100 cycles at a current density of 100 mA g-1. Meanwhile, the hollow Sn-Sb structure delivers a specific capacity of 451.3 mA h g-1 at 500 mA g-1 after 150 cycles when used for sodium ion batteries. The superior electrochemical performance that are higher than many reported results can be attributed to the special morphology and structure, which can shorten the transportation distance of lithium/sodium ion and provide extra free space to buffer the volume expansion during the lithium/sodium insertion/extraction.

  6. Direct laser interference patterning and ultrafast laser-induced micro/nano structuring of current collectors for lithium-ion batteries

    Science.gov (United States)

    Zheng, Y.; An, Z.; Smyrek, P.; Seifert, H. J.; Kunze, T.; Lang, V.; Lasagni, A.-F.; Pfleging, W.

    2016-03-01

    Laser-assisted modification of metals, polymers or ceramics yields a precise adjustment of wettability, biocompatibility or tribological properties for a broad range of applications. Due to a specific change of surface topography on micro- and nanometer scale, new functional properties can be achieved. A rather new scientific and technical approach is the laserassisted surface modification and structuring of metallic current collector foils for lithium-ion batteries. Prior to the thick film electrode coating processes, the formation of micro/nano-scaled surface topographies on current collectors can offer better interface adhesion, mechanical anchoring, electrical contact and reduced mechanical stress during cycling. These features in turn impact on the battery performance and the battery life-time. In order to generate the 3D surface architectures on metallic current collectors, two advanced laser processing structuring technologies: direct laser interference patterning (DLIP) and ultrafast laser-induced periodic surface structuring (LIPSS) were applied in this study. After laser structuring via DLIP and LIPSS, composite electrode materials were deposited by tape-casting on the modified current collectors. The electrode film adhesion was characterized by tensile strength measurements. The impact of various surface structures on the improvement of adhesive strength was discussed.

  7. Superhydrophobic hierarchical structures produced through novel low-cost stamp fabrication and hot embossing of thermoplastic film

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Chae Hee; Han, Sol Yi; Kim, Kwang; Kim, Wook Bae [Korea Polytechnic University, Siheung (Korea, Republic of); Eo, Jae Dong [SNDENG Co., Ltd., Ansan (Korea, Republic of)

    2015-11-15

    We present a simple and cost-effective method to produce super hydrophobic surfaces in thermoplastic polymer substrates, which contain hierarchical micro/nano structures that resemble lotus leaves. The method involved the fabrication of an Al stamp through the sequential application of laser ablation and anodization to create micro- and nano-structures, respectively. The fabricated patterns on the Al stamp were replicated on the thermoplastic Cyclic olefin copolymer (COC) film surfaces through a hot embossing technique. Static water contact angles were measured to evaluate the hydrophobicity of the patterned COC surfaces. The static water contact angle on the micro/nano hierarchical structured COC surface was measured to be 162.3 .deg. on average. The hot embossing process was repeated 31 times with a nano-structured Al stamp, and the replicated COC surfaces showed consistent water contact angles.

  8. Hierarchical Porous Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-07

    Materials Design is often at the forefront of technological innovation. While there has always been a push to generate increasingly low density materials, such as aero or hydrogels, more recently the idea of bicontinuous structures has gone more into play. This review will cover some of the methods and applications for generating both porous, and hierarchically porous structures.

  9. Effect of micro-nano-hybrid structured hydroxyapatite bioceramics on osteogenic and cementogenic differentiation of human periodontal ligament stem cell via Wnt signaling pathway.

    Science.gov (United States)

    Mao, Lixia; Liu, Jiaqiang; Zhao, Jinglei; Chang, Jiang; Xia, Lunguo; Jiang, Lingyong; Wang, Xiuhui; Lin, Kaili; Fang, Bing

    2015-01-01

    The surface structure of bioceramic scaffolds is crucial for its bioactivity and osteoinductive ability, and in recent years, human periodontal ligament stem cells have been certified to possess high osteogenic and cementogenic differential ability. In the present study, hydroxyapatite (HA) bioceramics with micro-nano-hybrid surface (mnHA [the hybrid of nanorods and microrods]) were fabricated via hydrothermal reaction of the α-tricalcium phosphate granules as precursors in aqueous solution, and the effects of mnHA on the attachment, proliferation, osteogenic and cementogenic differentiations of human periodontal ligament stem cells as well as the related mechanisms were systematically investigated. The results showed that mnHA bioceramics could promote cell adhesion, proliferation, alkaline phosphatase (ALP) activity, and expression of osteogenic/cementogenic-related markers including runt-related transcription factor 2 (Runx2), ALP, osteocalcin (OCN), cementum attachment protein (CAP), and cementum protein (CEMP) as compared to the HA bioceramics with flat and dense surface. Moreover, mnHA bioceramics stimulated gene expression of low-density lipoprotein receptor-related protein 5 (LRP5) and β-catenin, which are the key genes of canonical Wnt signaling. Moreover, the stimulatory effect on ALP activity and osteogenic and cementogenic gene expression, including that of ALP, OCN, CAP, CEMP, and Runx2 of mnHA bioceramics could be repressed by canonical Wnt signaling inhibitor dickkopf1 (Dkk1). The results suggested that the HA bioceramics with mnHA could act as promising grafts for periodontal tissue regeneration.

  10. Hierarchically Structured Electrospun Fibers

    Directory of Open Access Journals (Sweden)

    Nicole E. Zander

    2013-01-01

    Full Text Available Traditional electrospun nanofibers have a myriad of applications ranging from scaffolds for tissue engineering to components of biosensors and energy harvesting devices. The generally smooth one-dimensional structure of the fibers has stood as a limitation to several interesting novel applications. Control of fiber diameter, porosity and collector geometry will be briefly discussed, as will more traditional methods for controlling fiber morphology and fiber mat architecture. The remainder of the review will focus on new techniques to prepare hierarchically structured fibers. Fibers with hierarchical primary structures—including helical, buckled, and beads-on-a-string fibers, as well as fibers with secondary structures, such as nanopores, nanopillars, nanorods, and internally structured fibers and their applications—will be discussed. These new materials with helical/buckled morphology are expected to possess unique optical and mechanical properties with possible applications for negative refractive index materials, highly stretchable/high-tensile-strength materials, and components in microelectromechanical devices. Core-shell type fibers enable a much wider variety of materials to be electrospun and are expected to be widely applied in the sensing, drug delivery/controlled release fields, and in the encapsulation of live cells for biological applications. Materials with a hierarchical secondary structure are expected to provide new superhydrophobic and self-cleaning materials.

  11. The synergistic effect of micro/nano-structured and Cu(2+)-doped hydroxyapatite particles to promote osteoblast viability and antibacterial activity.

    Science.gov (United States)

    Shi, Feng; Liu, Yumei; Zhi, Wei; Xiao, Dongqin; Li, Hongyu; Duan, Ke; Qu, Shuxin; Weng, Jie

    2017-06-06

    Microstructure and chemical constitution are important factors affecting the biological activity of biomaterials. This study aimed to fabricate hydroxyapatite (HAp) particles with both micro/nanohybrid structure and Cu(2+) doping to promote osteogenic differentiation and antibacterial property. In the presence of inositol hexakisphosphate (IP6), micro/nano-structured and Cu(2+)-doped HAp (HAp-IP6-Cu) microspheres were successfully fabricated via hydrothermal method. Morphological observation showed that HAp-IP6-Cu microspheres with a diameter of 3.1-4.1 μm were chrysanthemum-like and composed of nano-flakes approximately 50 nm in thickness. Compared with the HAp micro-rods or IP6 modified HAp (HAp-IP6) microspheres, HAp-IP6-Cu microspheres had a larger specific surface area, better hydrophilicity and stronger ability to adsorb bovine serum albumin. To evaluate the synergistic effects of micro/nanohybrid structure and Cu(2+) on cell behavior, rat calvarial osteoblasts (RCOs) were cultured on HAp-IP6-Cu, HAp-IP6 and HAp layers as well as their extracts, respectively. Results demonstrated that HAp-IP6-Cu layer promoted the adhesion, proliferation and osteogenic differentiation of RCOs. The cells grew on HAp-IP6-Cu and HAp-IP6 layers exhibited greater spreading than those on HAp layer. In addition, quantitative test by the agar disk diffusion technique found that HAp-IP6-Cu microspheres were effectively against S taphylococcus aureus and E scherichia coli. These results demonstrated that HAp-IP6-Cu microspheres may be a potential candidate as a bioactive and anti-infective biomaterial for bone regeneration.

  12. Contact Angle Model and Wettability on the Surfaces with Micro/nano Binary Structures%微纳双重结构表面的接触角模型及其润湿性研究

    Institute of Scientific and Technical Information of China (English)

    李小兵

    2014-01-01

    Based on super hydrophobic and self-cleaning lotus leaf surface with the dual structures of micro mastoid and nano flagellar,the micro/nano structures similar to lotus leaf surface was designed.The corresponding contact angle models with Wenzel and Cassie model were established and the influences of the micro-nano dual structures and its structure pa-rameters on surface wettability were analyzed.The results show that for single microstructure,the rough surface with a slen-der structure (that is with the larger ratio of columns height and column side length)has a better hydrophobic effect.For micro-nano dual structure,the threshold ratio of column height and column length to implement super hydrophobic is re-duced due to the second nano structures.Therefore,the micro-nano dual structures can greatly improve the hydrophobic properties of rough surface.%依据超疏水、自清洁荷叶表面具有的微米乳突和纳米鞭毛双重结构,设计类似荷叶表面的微/纳双重结构,建立对应的Wenzel、Cassie接触角模型,分析微纳双重结构及其结构参数对表面润湿性的影响。研究表明,对于单级微观结构,具有细长(较大的柱高与柱边长比)微观结构的粗糙表面疏水效果更好;对于微纳双重结构,二级纳米结构的出现降低了实现超疏水性的柱高与柱边长比的阈值,微纳双重结构可以大大提高表面的疏水性能。

  13. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei

    2011-01-01

    This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  14. A gecko skin micro/nano structure - A low adhesion, superhydrophobic, anti-wetting, self-cleaning, biocompatible, antibacterial surface.

    Science.gov (United States)

    Watson, Gregory S; Green, David W; Schwarzkopf, Lin; Li, Xin; Cribb, Bronwen W; Myhra, Sverre; Watson, Jolanta A

    2015-07-01

    Geckos, and specifically their feet, have attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10 to 20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various size ranges from microns to several millimetres. Water droplets which are sufficiently small (10-100 μm) can easily access valleys between the scales for efficient self-cleaning and due to their dimensions can self-propel off the surface enhancing their mobility and cleaning effect. In addition, we demonstrate that the gecko skin has an antibacterial action where Gram-negative bacteria (Porphyromonas gingivalis) are killed when exposed to the surface however eukaryotic cell compatibility (with human stem cells) is demonstrated. The multifunctional features of the gecko skin provide a potential natural template for man-made applications where specific control of liquid, solid and biological contacts is required.

  15. Effect of micro-nano-hybrid structured hydroxyapatite bioceramics on osteogenic and cementogenic differentiation of human periodontal ligament stem cell via Wnt signaling pathway

    Directory of Open Access Journals (Sweden)

    Mao LX

    2015-11-01

    Full Text Available Lixia Mao,1,* Jiaqiang Liu,1,* Jinglei Zhao,1 Jiang Chang,2 Lunguo Xia,1 Lingyong Jiang,1 Xiuhui Wang,2 Kaili Lin,2,3 Bing Fang11Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Science, Top Priority Clinical Medical Center of Shanghai Municipal Commission of Health and Family Planning, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Jiao Tong University, 2State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 3Shanghai Engineering Research Center of Tooth Restoration and Regeneration, School of Stomatology, Tongji University, Shanghai, People’s Republic of China*These authors contributed equally to this workAbstract: The surface structure of bioceramic scaffolds is crucial for its bioactivity and osteoinductive ability, and in recent years, human periodontal ligament stem cells have been certified to possess high osteogenic and cementogenic differential ability. In the present study, hydroxyapatite (HA bioceramics with micro-nano-hybrid surface (mnHA [the hybrid of nanorods and microrods] were fabricated via hydrothermal reaction of the α-tricalcium phosphate granules as precursors in aqueous solution, and the effects of mnHA on the attachment, proliferation, osteogenic and cementogenic differentiations of human periodontal ligament stem cells as well as the related mechanisms were systematically investigated. The results showed that mnHA bioceramics could promote cell adhesion, proliferation, alkaline phosphatase (ALP activity, and expression of osteogenic/cementogenic-related markers including runt-related transcription factor 2 (Runx2, ALP, osteocalcin (OCN, cementum attachment protein (CAP, and cementum protein (CEMP as compared to the HA bioceramics with flat and dense surface. Moreover, mnHA bioceramics stimulated gene expression of low-density lipoprotein receptor

  16. Detecting Hierarchical Structure in Networks

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard;

    2012-01-01

    a generative Bayesian model that is able to infer whether hierarchies are present or not from a hypothesis space encompassing all types of hierarchical tree structures. For efficient inference we propose a collapsed Gibbs sampling procedure that jointly infers a partition and its hierarchical structure......Many real-world networks exhibit hierarchical organization. Previous models of hierarchies within relational data has focused on binary trees; however, for many networks it is unknown whether there is hierarchical structure, and if there is, a binary tree might not account well for it. We propose....... On synthetic and real data we demonstrate that our model can detect hierarchical structure leading to better link-prediction than competing models. Our model can be used to detect if a network exhibits hierarchical structure, thereby leading to a better comprehension and statistical account the network....

  17. Enhancement of hydrogen production from MeOH/H2O photo-splitting using micro-/nano-structured SrSnO3/TiO2 composite catalysts.

    Science.gov (United States)

    Kim, Kang Min; Kang, Sora; Kwak, Byeong Sub; Kang, Misook

    2014-12-01

    Micro-/nano-structured SrSnO3/x wt.-% TiO2 composites (x = 10, 20, and 30) were designed using a mixed method, a typical hydrothermal and impregnation method, to enhance hydrogen production from MeOH/H2O photo-splitting. All the materials obtained exhibited a perovskite structure. Scanning electron microscopy revealed pure SrSnO3 to have a rod-like morphology with a square base, 0.7-1.5 μm in size, and a height of approximately 2.0-3.0 μm. Moreover, phenomena were observed in the rods similar to that of typical perovskite with a layered structure. TiO2 nanoparticles, nano-structured SrSnO/TiO2 composite was enhanced compared to that over pure SrSnO3. In particular, 0.033 mmol of H2 gas was collected after 10 h under an 18 W-lamp with 365 nm radiation when 0.5 g of a SrSnO3/TiO2 20 wt.-% composite was used. Based on cyclic voltammetry and ultraviolet-visible spectroscopy, it was expected that the high photo activity resulted from the decrease in electron-hole recombination on the micro-/nano-structured SrSnO3/TiO2 composite.

  18. Mechanisms of Cdc42-mediated rat MSC differentiation on micro/nano-textured topography.

    Science.gov (United States)

    Li, Guangwen; Song, Yanyan; Shi, Mengqi; Du, Yuanhong; Wang, Wei; Zhang, Yumei

    2017-02-01

    -textured topography and the underlying mechanisms are not well understood. This study shows that the micropitted/nanotubular hierarchical topography produced by etching and anodic oxidation treatment drives fusiform cell morphology, cytoskeletal reorganization as well as better MSCs osteogenic differentiation. The cross-talk between Cdc42 pathway and Wnt/β-catenin pathway though GSK3β modulates the osteoinductive effect of the micro/nano-textured topography on MSCs. This finding sheds light on a novel mechanism involved in micro/nano-textured surface-mediated MSCs osteogenic differentiation and is a major step in the development of new surface modifications aiming to accelerate and enhance the process of osseointegration. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. The Extraction of Characteristic Parameters of Micro-nano Dual Structure Made by Laser Interference%激光干涉微纳双重结构调制周期的提取

    Institute of Scientific and Technical Information of China (English)

    连凡凡; 胡贞

    2014-01-01

    Set up three beams light path,four beams light path and six beams light path respectively by using the laser interference lithography, conduct the optical interference and obtain the result of image acquisition experiment. Make a image processing for the acquired image by Matlab, extract the micro-nano dual structure modulation cycle, compare with theoretical calculation cycle value, and verify feasibility of the program. The measurement of modulation cycle lay a foundation for subsequent extraction of micro-nano other characteristic parameters of the dual structure.%为了制备质量更高的微纳双重结构,采用激光干涉光刻技术,分别搭建三光束、四光束和六光束光路进行光干涉,对干涉结果进行图像采集的实验。采用图像处理的方法对采集的图像进行处理,提取了微纳双重结构的调制周期,并与理论周期值进行比较,验证方法的可行性,为后续提取微纳双重结构的其它特征参数奠定了基础。

  20. Silicon Micro/Nano Structures for High Efficiency Solar Cells and Their Preparation%用于高效太阳电池的硅基微纳结构及制备

    Institute of Scientific and Technical Information of China (English)

    窦丙飞; 贾锐; 陈晨; 李昊峰; 岳会会; 陈宝钦; 刘新宇; 叶甜春

    2011-01-01

    介绍了用于高效太阳电池的几种硅基微纳结构的最新研究进展,重点介绍了几种硅基微纳结构的制备方法,如阳极腐蚀制备多孔硅、各向异性制绒以及气液固(VLS)生长纳米线等,并对各种方法的特点作了分析比较,指出了各种方法存在的问题.最后对今后研究的方向做了展望,由于太阳电池在性能提高以及产业应用方面的需求,未来用于高效太阳电池的硅基微纳结构仍是研究的热点之一.进一步提升其对太阳电池效率的优化能力将是研究的重要关注点,而其制备技术也将向着低成本、大规模及可控制的方向发展.%The latest research progresses of several silicon micro/nano structures which applied on high efficiency solar cells are introduced, with the emphasis on the fabrication methods of these structures, such as anodic etching for porous silicon, anisotropic etching for pyramids and vapor-liquid-solid for nanowires. The characteristics of these methods are analysed and compared, and the existed problems are pointed out. Finally, the research direction in future is prospected. Because of the demand of solar cells in performance improvement and industrial applications, the silicon micro/nano structures for high efficient solar cells are still one of hot topics in future. The optimizing ability of the silicon micro/nano structures to further enhance the solar cells efficiency will be the main research focus, and their fabrication techniques will develop toward the direction of low cost, large scale and easy control.

  1. Thermodynamic analysis on an anisotropically superhydrophobic surface with a hierarchical structure

    Science.gov (United States)

    Zhao, Jieliang; Su, Zhengliang; Yan, Shaoze

    2015-12-01

    Superhydrophobic surfaces, which refer to the surfaces with contact angle higher than 150° and hysteresis less than 10°, have been reported in various studies. However, studies on the superhydrophobicity of anisotropic, hierarchical surfaces are limited and the corresponding thermodynamic mechanisms could not be explained thoroughly. Here we propose a simplified surface model of anisotropic patterned surface with dual scale roughness. Based on the thermodynamic method, we calculate the equilibrium contact angle (ECA) and the contact angle hysteresis (CAH) on the given surface. We show here that the hierarchical structure has much better anisotropic wetting properties than the single-scale one, and the results shed light on the potential application in controllable micro-/nano-fluidic systems. Our studies can be potentially applied for the fabrication of anisotropically superhydrophobic surfaces.

  2. Trees and Hierarchical Structures

    CERN Document Server

    Haeseler, Arndt

    1990-01-01

    The "raison d'etre" of hierarchical dustering theory stems from one basic phe­ nomenon: This is the notorious non-transitivity of similarity relations. In spite of the fact that very often two objects may be quite similar to a third without being that similar to each other, one still wants to dassify objects according to their similarity. This should be achieved by grouping them into a hierarchy of non-overlapping dusters such that any two objects in ~ne duster appear to be more related to each other than they are to objects outside this duster. In everyday life, as well as in essentially every field of scientific investigation, there is an urge to reduce complexity by recognizing and establishing reasonable das­ sification schemes. Unfortunately, this is counterbalanced by the experience of seemingly unavoidable deadlocks caused by the existence of sequences of objects, each comparatively similar to the next, but the last rather different from the first.

  3. Structural integrity of hierarchical composites

    Directory of Open Access Journals (Sweden)

    Marco Paggi

    2012-01-01

    Full Text Available Interface mechanical problems are of paramount importance in engineering and materials science. Traditionally, due to the complexity of modelling their mechanical behaviour, interfaces are often treated as defects and their features are not explored. In this study, a different approach is illustrated, where the interfaces play an active role in the design of innovative hierarchical composites and are fundamental for their structural integrity. Numerical examples regarding cutting tools made of hierarchical cellular polycrystalline materials are proposed, showing that tailoring of interface properties at the different scales is the way to achieve superior mechanical responses that cannot be obtained using standard materials

  4. Effects of hydrofluoric acid and anodised micro and micro/nano surface implants on early osseointegration in rats.

    Science.gov (United States)

    Li, Yongfeng; Gao, Yuan; Shao, Bo; Xiao, Jianrui; Hu, Kaijin; Kong, Liang

    2012-12-01

    Our aim was to evaluate the effects of hydrofluoric acid and anodised micro and micro/nano surface implants on bony ingrowth in the earliest stage of implantation in rats. Sixty cylindrical screwed titanium alloy implants with machined, micro, and hierarchical hybrid micro/nano surfaces (n=20 in each group) were inserted into the distal femurs of 30 female Sprague-Dawley rats. In vivo microcomputed tomography (micro CT) was used to assess microarchitectural changes in the bone around the implants 2 weeks after implantation. All the animals were then killed and the femurs with implants harvested for histological analysis and pull-out testing. Micro CT analysis showed that the trabecular thickness and the bone:volume ratio (bone volume:total volume) (BV:TV) increased significantly in the micro/nano group compared with the other two groups, while the trabecular separation decreased significantly in the micro/nano group compared with the machined group. The mean (SD) bone-implant contacts (%) were 38.94 (9.48), 41.67 (8.71), and 51.49 (12.49) in the machined, micro, and micro/nano groups, respectively. The maximum pull-out forces (N) were 64.95 (6.11), 71.45 (7.15), and 81.90 (13.1), respectively. Both bone-implant contacts and maximum pull-out forces were significantly higher in the micro/nano group, but there was no significant difference between the micro group and the machined group. These data indicate that the hierarchical hybrid micro/nano surface of the implant can promote osseointegration in the earliest stage of implantation, and may be a promising option for further clinical use.

  5. Hierarchically Structured Electrospun Fibers

    Science.gov (United States)

    2013-01-07

    range of fluorescence could be tuned from yellow-green to blue , making these fibers ideal for micro- and nano-optoelectronic devices [144]. Figure 7...forces. Rapid phase separation of the distorted droplet and energy minimization may lead to the formation of the spider -web-like structure of the fiber...engineering cellularized blood vessels. Biomaterials 2010, 31, 4313–4321. 59. Thorvaldsson, A.; Stenhamre, H.; Gatenholm, P.; Walkenstrom, P

  6. Enhancement of osteogenesis on micro/nano-topographical carbon fiber-reinforced polyetheretherketone–nanohydroxyapatite biocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Anxiu [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China); Liu, Xiaochen [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Gao, Xiang; Deng, Feng [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China); Deng, Yi, E-mail: 18210357357@163.com [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China); Wei, Shicheng, E-mail: weishicheng99@163.com [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China)

    2015-03-01

    As an FDA-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses excellent mechanical properties similar to those of human cortical bone and is a prime candidate to replace conventional metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. The present work aimed at developing a novel carbon fiber-reinforced polyetheretherketone–nanohydroxyapatite (PEEK/CF/n-HA) ternary biocomposite with micro/nano-topographical surface for the enhancement of the osteogenesis as a potential bioactive material for bone grafting and bone tissue-engineering applications. The combined modification of oxygen plasma and sand-blasting could improve the hydrophily and generate micro/nano-topographical structures on the surface of the CFRPEEK-based ternary biocomposite. The results clearly showcased that the micro-/nano-topographical PEEK/n-HA/CF ternary biocomposite demonstrated the outstanding ability to promote the proliferation and differentiation of MG-63 cells in vitro as well as to boost the osseointegration between implant and bone in vivo, thereby boding well application to bone tissue engineering. - Highlights: • A novel micro/nano-topographical PEEK/n-HA/CF ternary biocomposite was developed. • The modified PEEK biocomposite promotes proliferation and differentiation of cells. • In vivo osseointegration of the micro/nano-topographical PEEK/n-HA/CF was enhanced.

  7. Micro/nano-fabrication technologies for cell biology.

    Science.gov (United States)

    Qian, Tongcheng; Wang, Yingxiao

    2010-10-01

    Micro/nano-fabrication techniques, such as soft lithography and electrospinning, have been well-developed and widely applied in many research fields in the past decade. Due to the low costs and simple procedures, these techniques have become important and popular for biological studies. In this review, we focus on the studies integrating micro/nano-fabrication work to elucidate the molecular mechanism of signaling transduction in cell biology. We first describe different micro/nano-fabrication technologies, including techniques generating three-dimensional scaffolds for tissue engineering. We then introduce the application of these technologies in manipulating the physical or chemical micro/nano-environment to regulate the cellular behavior and response, such as cell life and death, differentiation, proliferation, and cell migration. Recent advancement in integrating the micro/nano-technologies and live cell imaging are also discussed. Finally, potential schemes in cell biology involving micro/nano-fabrication technologies are proposed to provide perspectives on the future research activities.

  8. Treatment Protocols as Hierarchical Structures

    Science.gov (United States)

    Ben-Bassat, Moshe; Carlson, Richard W.; Puri, Vinod K.; Weil, Max Harry

    1978-01-01

    We view a treatment protocol as a hierarchical structure of therapeutic modules. The lowest level of this structure consists of individual therapeutic actions. Combinations of individual actions define higher level modules, which we call routines. Routines are designed to manage limited clinical problems, such as the routine for fluid loading to correct hypovolemia. Combinations of routines and additional actions, together with comments, questions, or precautions organized in a branching logic, in turn, define the treatment protocol for a given disorder. Adoption of this modular approach may facilitate the formulation of treatment protocols, since the physician is not required to prepare complex flowcharts. This hierarchical approach also allows protocols to be updated and modified in a flexible manner. By use of such a standard format, individual components may be fitted together to create protocols for multiple disorders. The technique is suited for computer implementation. We believe that this hierarchical approach may facilitate standarization of patient care as well as aid in clinical teaching. A protocol for acute pancreatitis is used to illustrate this technique.

  9. Hierarchical structure of biological systems

    Science.gov (United States)

    Alcocer-Cuarón, Carlos; Rivera, Ana L; Castaño, Victor M

    2014-01-01

    A general theory of biological systems, based on few fundamental propositions, allows a generalization of both Wierner and Berthalanffy approaches to theoretical biology. Here, a biological system is defined as a set of self-organized, differentiated elements that interact pair-wise through various networks and media, isolated from other sets by boundaries. Their relation to other systems can be described as a closed loop in a steady-state, which leads to a hierarchical structure and functioning of the biological system. Our thermodynamical approach of hierarchical character can be applied to biological systems of varying sizes through some general principles, based on the exchange of energy information and/or mass from and within the systems. PMID:24145961

  10. [Study on spectroscopic characterization and property of PES/ micro-nano cellulose composite membrane material].

    Science.gov (United States)

    Tang, Huan-Wei; Zhang, Li-Ping; Li, Shuai; Zhao, Guang-Jie; Qin, Zhu; Sun, Su-Qin

    2010-03-01

    In the present paper, the functional groups of PES/micro-nano cellulose composite membrane materials were characterized by Fourier transform infrared spectroscopy (FTIR). Also, changes in crystallinity in composite membrane materials were analyzed using X-ray diffraction (XRD). The effects of micro-nano cellulose content on hydrophilic property of composite membrane material were studied by measuring hydrophilic angle. The images of support layer structure of pure PES membrane material and composite membrane material were showed with scanning electron microscope (SEM). These results indicated that in the infrared spectrogram, the composite membrane material had characteristic peaks of both PES and micro-nano cellulose without appearance of other new characteristics peaks. It revealed that there were no new functional groups in the composite membrane material, and the level of molecular compatibility was achieved, which was based on the existence of inter-molecular hydrogen bond association between PES and micro-nano cellulose. Due to the existence of micro-nano cellulose, the crystallinity of composite membrane material was increased from 37.7% to 47.9%. The more the increase in micro-nano cellulose mass fraction, the better the van de Waal force and hydrogen bond force between composite membrane material and water were enhanced. The hydrophilic angle of composite membrane material was decreased from 55.8 degrees to 45.8 degrees and the surface energy was raised from 113.7 to 123.5 mN x m(-2). Consequently, the hydrophilic property of composite membrane material was improved. The number of pores in the support layer of composite membrane material was lager than that of pure PES membrane. Apparently, pores were more uniformly distributed.

  11. Modeling hierarchical structures - Hierarchical Linear Modeling using MPlus

    CERN Document Server

    Jelonek, M

    2006-01-01

    The aim of this paper is to present the technique (and its linkage with physics) of overcoming problems connected to modeling social structures, which are typically hierarchical. Hierarchical Linear Models provide a conceptual and statistical mechanism for drawing conclusions regarding the influence of phenomena at different levels of analysis. In the social sciences it is used to analyze many problems such as educational, organizational or market dilemma. This paper introduces the logic of modeling hierarchical linear equations and estimation based on MPlus software. I present my own model to illustrate the impact of different factors on school acceptation level.

  12. ZnO micro-nano composite hydrophobic film prepared by the three-step method

    Institute of Scientific and Technical Information of China (English)

    Ma Kai; Li Hua; Zhang Han; Xu Xiao-Liang; Gong Mao-Gang; Yang Zhou

    2009-01-01

    The hydrophobicity of the lotus leaf is mainly due to its surface micro-nano composite structure. In order to mimic the lotus structure, ZnO micro-nano composite hydrophobic films were prcpared via the three-step method. On thin buffer films of SiO2, which were first fabricated on glass substrates by the sol gel dip-coating method, a ZnO seed layer was deposited via RF magnetron sputtering. Then two different ZnO films, micro-nano and micro-only flower-like structures, were grown by the hydrothermal method. The prepared films have different hydrophobic properties after surface modification. The structures of the obtained ZnO films were characterized using x-ray diffraction and field-emission scanning electron microscopy. A conclusion that a micro-nano composite structure is more beneficial to hydrophobicity than a micro-only structure was obtained through research into the effect of structure on hydrophobic properties.

  13. ZnO micro-nano composite hydrophobic film prepared by the three-step method

    Science.gov (United States)

    Ma, Kai; Li, Hua; Zhang, Han; Xu, Xiao-Liang; Gong, Mao-Gang; Yang, Zhou

    2009-05-01

    The hydrophobicity of the lotus leaf is mainly due to its surface micro-nano composite structure. In order to mimic the lotus structure, ZnO micro-nano composite hydrophobic films were prepared via the three-step method. On thin buffer films of SiO2, which were first fabricated on glass substrates by the sol-gel dip-coating method, a ZnO seed layer was deposited via RF magnetron sputtering. Then two different ZnO films, micro-nano and micro-only flower-like structures, were grown by the hydrothermal method. The prepared films have different hydrophobic properties after surface modification. The structures of the obtained ZnO films were characterized using x-ray diffraction and field-emission scanning electron microscopy. A conclusion that a micro-nano composite structure is more beneficial to hydrophobicity than a micro-only structure was obtained through research into the effect of structure on hydrophobic properties.

  14. Micro Nano Replication Processes and Applications

    CERN Document Server

    Kang, Shinill

    2012-01-01

    This book is an introduction to the fundamentals and processes for micro and nano molding for plastic components. In addition to the basics, the book covers applications details and examples. The book helps both students and professionals to understand and work with the growing tools of molding and uses for micro and nano-sized plastic parts.Provides a comprehensive presentation on fundamentals and practices of manufacturing for micro / nano sized plastics partsCovers a relatively new but fast-growing field that is impacting any industry using plastic parts in their products (electronics, tele

  15. Modeling hierarchical structures - Hierarchical Linear Modeling using MPlus

    OpenAIRE

    Jelonek, Magdalena

    2006-01-01

    The aim of this paper is to present the technique (and its linkage with physics) of overcoming problems connected to modeling social structures, which are typically hierarchical. Hierarchical Linear Models provide a conceptual and statistical mechanism for drawing conclusions regarding the influence of phenomena at different levels of analysis. In the social sciences it is used to analyze many problems such as educational, organizational or market dilemma. This paper introduces the logic of m...

  16. Thermodynamic analysis on an anisotropically superhydrophobic surface with a hierarchical structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jieliang [Division of Intelligent and Biomechanical Systems, State Key Laboratory of Tribology, Tsinghua University, Room 3407, Building 9003, 100084 Beijing (China); Su, Zhengliang [Division of Intelligent and Biomechanical Systems, State Key Laboratory of Tribology, Tsinghua University, Room 3407, Building 9003, 100084 Beijing (China); Department of Automotive Engineering, Tsinghua University, Beijing 100084 (China); Yan, Shaoze, E-mail: yansz@mail.tsinghua.edu.cn [Division of Intelligent and Biomechanical Systems, State Key Laboratory of Tribology, Tsinghua University, Room 3407, Building 9003, 100084 Beijing (China)

    2015-12-01

    Graphical abstract: - Highlights: • We model the superhydrophobic surface with anisotropic and hierarchical structure. • Anisotropic wetting only shows in noncomposite state (not in composite state). • Transition from noncomposite to composite state on dual-scale structure is hard. • Droplets tend to roll in the particular direction. • Droplets tend to stably remain in one preferred thermodynamic state. - Abstract: Superhydrophobic surfaces, which refer to the surfaces with contact angle higher than 150° and hysteresis less than 10°, have been reported in various studies. However, studies on the superhydrophobicity of anisotropic, hierarchical surfaces are limited and the corresponding thermodynamic mechanisms could not be explained thoroughly. Here we propose a simplified surface model of anisotropic patterned surface with dual scale roughness. Based on the thermodynamic method, we calculate the equilibrium contact angle (ECA) and the contact angle hysteresis (CAH) on the given surface. We show here that the hierarchical structure has much better anisotropic wetting properties than the single-scale one, and the results shed light on the potential application in controllable micro-/nano-fluidic systems. Our studies can be potentially applied for the fabrication of anisotropically superhydrophobic surfaces.

  17. Hierarchical Structures in Hypertext Learning Environments

    NARCIS (Netherlands)

    Bezdan, Eniko; Kester, Liesbeth; Kirschner, Paul A.

    2011-01-01

    Bezdan, E., Kester, L., & Kirschner, P. A. (2011, 9 September). Hierarchical Structures in Hypertext Learning Environments. Presentation for the visit of KU Leuven, Open University, Heerlen, The Netherlands.

  18. Optimal design for bio-mimicking micro-nano structures on Morpho butterfly wing%仿Morpho蝴蝶翅膀微纳结构的优化设计

    Institute of Scientific and Technical Information of China (English)

    夏奇; 任飞多; 高阳; 史铁林

    2012-01-01

    鉴于Morpho蝴蝶翅膀呈耀眼蓝色光泽与蝶翅表面的微纳结构有密切联系,提出了一种服务于仿生微纳制造的优化设计方法.根据生物结构的形状与尺寸,结合微纳制造中的工艺约束,建立了便于制造的仿生模型.使用严格耦合波分析对仿生模型进行光学仿真计算.在此基础上,以提高仿生结构的蓝光波段(特征波长为470nm)反射率为目标,利用遗传算法对仿生模型进行了优化设计.所得到的最优结构反射率波峰均位于470nm附近,且反射率明显高于仿生结构.为了分析最优结构的蓝光波段高反射率机理,研究了不同层数最优结构的几何特征,计算了部分结构的磁场强度分布,确定了结构中影响反射率的主要参数.%Brilliant and iridescent blue color of Morpho butterfly's wing is closely related to micronano structures of the wing. Based on the structural color, an optimal design approach was proposed to facilitate manufacturing artificial micro-nano structures that exhibit the same structural color. First, a biomimetic model was constructed via simplifying the shape of the butterfly structure and at the same time subject to the constraints of a given manufacturing technique. Then, the biomimetic model was optimized with the target of maximizing the reflectivity at blue band (wavelength of 470 nm). All the resulting optimal structures have maximal reflection at about 470 nm, and the reflection peaks are higher than that of the biomimetic model. The geometrical characteristics of the optimal structures were studied and the magnetic field maps were calculated. The results were used to analyze the mechanisms of high reftectivity of the optimal structures. The main parameters affecting the re flectivity were discussed.

  19. A cytocompatible micro/nano-textured surface with Si-doped titania mesoporous arrays fabricated by a one-step anodization.

    Science.gov (United States)

    Liu, Huibing; Huang, Xiaobo; Yu, Hanwu; Yang, Xiaoning; Zhang, Xiangyu; Hang, Ruiqiang; Tang, Bin

    2017-04-01

    To mimic the hierarchical structure of bone tissues, a hybrid micro/nano-textured titanium surface with Si-doped TiO2 mesoporous arrays is fabricated by a one-step high current anodization (HCA). Specifically, the HCA is carried out in a electrolyte containing NO3(-) and SiO3(2-). The NO3(-) in the electrolyte is demonstrated to play a key role in mediating the formation of honeycombed TiO2 mesoporous arrays, which are different than the nanotubes formed by the mediating of F(-) ion in the conventional anodization. This unique structure endows the coating with improved mechanical properties compared to the nanotube layer. In addition, the Si is incorporated into the coating in a concentration-dependent manner. With the increase of Si doping amount in the coating, both the hydrophilic properties and surface free energy of coatings are obviously enhanced. The cell culture test shows that the osteoblast behaviors on this surface are positively influenced by the doped Si. Therefore, this micro/nano-textured surface coating doped with Si may endow the Ti-based implants long-term stability and good osseointegration.

  20. Biomass carbon micro/nano-structures derived from ramie fibers and corncobs as anode materials for lithium-ion and sodium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Qiang; Zhang, Zhenghao [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan 430062 (China); Yin, Shengyu [College of Environmental and Biological Engineering, Wuhan Technology and Business University, Wuhan 430065 (China); Guo, Zaiping [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan 430062 (China); Institute for Superconducting & Electronic Materials, University of Wollongong, NSW 2522 (Australia); Wang, Shiquan [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan 430062 (China); Feng, Chuanqi, E-mail: cfeng@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan 430062 (China)

    2016-08-30

    Highlights: • Ramie fibers and corncobs are used as precursors to prepare the biomass carbons. • The ramie fiber carbon (RFC) took on morphology of 3D micro-rods. • The corncob carbon (CC) possessed a 2D nanosheets structure. • Both RFC and CC exhibited outstanding electrochemical performances in LIBs and SIBs systems. - Abstract: Three-dimensional (3D) rod-like carbon micro-structures derived from natural ramie fibers and two-dimensional (2D) carbon nanosheets derived from corncobs have been fabricated by heat treatment at 700 °C under argon atomsphere. The structure and morphology of the as-obtained ramie fiber carbon (RFC) and corncob carbon (CC) were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technique. The electrochemical performances of the biomass carbon-based anode in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) were investigated. When tested as anode material for lithium ion batteries, both the RFC microrods and CC nanosheets exhibited high capacity, excellent rate capability, and stable cyclability. The specific capacity were still as high as 489 and 606 mAhg{sup −1} after 180 cycles when cycled at room temperature in a 3.0–0.01 V potential (vs. Li/Li{sup +}) window at current density of 100 mAg{sup −1}, respectively, which are much higher than that of graphite (375 mAhg{sup −1}) under the same current density. Although the anodes in sodium ion batteries showed poorer specific capability than that in lithium-ion batteries, they still achieve a reversible sodium intercalation capacity of 122 and 139 mAhg{sup −1} with similar cycling stability. The feature of stable cycling performance makes the biomass carbon derived from natural ramie fibers and corncobs to be promising candidates as electrodes in rechargeable sodium-ion batteries and lithium-ion batteries.

  1. Chemical-mechanical stability of the hierarchical structure of shell nacre

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hierarchical structure and mechanical property of shell nacre are experimentally investigated from the new aspects of chemical stability and chemistry-mechanics coupling. Through chemical deproteinization or demineralization methods together with characterization techniques at micro/nano scales,it is found that the nacre of abalone,haliotis discus hannai,contains a hierarchical structure stacked with irregular aragonite platelets and interplatelet organic matrix thin layers. Yet the aragonite platelet itself is a nanocomposite consisting of nanoparticles and intraplatelet organic matrix framework. The mean diameter of the nanoparticles and the distribution of framework are quite different for different platelets. Though the interplatelet and in-traplatelet organic matrix can be both decomposed by sodium hydroxide solution,the chemical stability of individual aragonite platelets is much higher than that of the microstructure stacked with them. Further,macroscopic bending test or nanoindentation experiment is performed on the micro/nanostructure of nacre after sodium hydroxide treatment. It is found that the Young’s modulus of both the stacked microstructure and nanocomposite platelet reduced. The reduction of the microstructure is more remark than that of the platelet. Therefore the chemical-mechanical stability of the nanocomposite platelet itself is much higher than that of the stacked microstructure of nacre.

  2. Biomass carbon micro/nano-structures derived from ramie fibers and corncobs as anode materials for lithium-ion and sodium-ion batteries

    Science.gov (United States)

    Jiang, Qiang; Zhang, Zhenghao; Yin, Shengyu; Guo, Zaiping; Wang, Shiquan; Feng, Chuanqi

    2016-08-01

    Three-dimensional (3D) rod-like carbon micro-structures derived from natural ramie fibers and two-dimensional (2D) carbon nanosheets derived from corncobs have been fabricated by heat treatment at 700 °C under argon atomsphere. The structure and morphology of the as-obtained ramie fiber carbon (RFC) and corncob carbon (CC) were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technique. The electrochemical performances of the biomass carbon-based anode in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) were investigated. When tested as anode material for lithium ion batteries, both the RFC microrods and CC nanosheets exhibited high capacity, excellent rate capability, and stable cyclability. The specific capacity were still as high as 489 and 606 mAhg-1 after 180 cycles when cycled at room temperature in a 3.0-0.01 V potential (vs. Li/Li+) window at current density of 100 mAg-1, respectively, which are much higher than that of graphite (375 mAhg-1) under the same current density. Although the anodes in sodium ion batteries showed poorer specific capability than that in lithium-ion batteries, they still achieve a reversible sodium intercalation capacity of 122 and 139 mAhg-1 with similar cycling stability. The feature of stable cycling performance makes the biomass carbon derived from natural ramie fibers and corncobs to be promising candidates as electrodes in rechargeable sodium-ion batteries and lithium-ion batteries.

  3. Discovering hierarchical structure in normal relational data

    DEFF Research Database (Denmark)

    Schmidt, Mikkel Nørgaard; Herlau, Tue; Mørup, Morten

    2014-01-01

    Hierarchical clustering is a widely used tool for structuring and visualizing complex data using similarity. Traditionally, hierarchical clustering is based on local heuristics that do not explicitly provide assessment of the statistical saliency of the extracted hierarchy. We propose a non-param...

  4. Hierarchically structured, nitrogen-doped carbon membranes

    KAUST Repository

    Wang, Hong

    2017-08-03

    The present invention is a structure, method of making and method of use for a novel macroscopic hierarchically structured, nitrogen-doped, nano-porous carbon membrane (HNDCMs) with asymmetric and hierarchical pore architecture that can be produced on a large-scale approach. The unique HNDCM holds great promise as components in separation and advanced carbon devices because they could offer unconventional fluidic transport phenomena on the nanoscale. Overall, the invention set forth herein covers a hierarchically structured, nitrogen-doped carbon membranes and methods of making and using such a membranes.

  5. Study of the Raman-AFM System for Simultaneous Measurements of Raman Spectrum and Micro/Nano-Structures%用于Raman光谱与微纳米结构同步检测的Raman-AFM系统研究

    Institute of Scientific and Technical Information of China (English)

    史斌; 章海军; 吴兰; 张冬仙

    2012-01-01

    研究和发展了一种将微区拉曼(Raman)光谱检测与原子力显微镜(AFM)微纳米扫描成像相结合的新型Raman-AFM技术.设计了Raman光谱与AFM扫描成像的原位检测探头;研制出相应的Raman-AFM系统;利用该系统,对ZnO纳米颗粒和TiO2纳米薄膜开展了微区Raman光谱与微纳米结构的检测实验.研究表明,所获得的Raman光谱检测结果与理论值良好吻合,同时,AFM扫描检测得到的图像很好地表征了样品的微纳米结构,从而实现了微区Raman光谱与AFM图像的原位及同步检测,验证了这一技术的可行性,为Raman光谱技术与微纳米技术领域的实际应用提供了技术基础.%This paper proposes a novel technique of Raman-atomic force microscopy (AFM) combining micro region Raman spec-troscopy and AFM imaging. An in-situ probe unit which can simultaneously realize the detection of Raman spectrum and the measurement of AFM image was designed, and a related Raman-AFM system was constructed. Using this system, some experiments were carried out to acquire micro region Raman spectra and AFM images of ZnO nano-particle and TiO2 film. The results show that the Raman spectra of both samples are in agreement with theoretical vaues, and the AFM images represent their mi-cro/nano-structures quite well. These researches prove the feasibility of the Raman-AFM technique which has the potential of being widely applied in the fields of Raman spectroscopy and micro/nano-technology.

  6. Evaluating Hierarchical Structure in Music Annotations.

    Science.gov (United States)

    McFee, Brian; Nieto, Oriol; Farbood, Morwaread M; Bello, Juan Pablo

    2017-01-01

    Music exhibits structure at multiple scales, ranging from motifs to large-scale functional components. When inferring the structure of a piece, different listeners may attend to different temporal scales, which can result in disagreements when they describe the same piece. In the field of music informatics research (MIR), it is common to use corpora annotated with structural boundaries at different levels. By quantifying disagreements between multiple annotators, previous research has yielded several insights relevant to the study of music cognition. First, annotators tend to agree when structural boundaries are ambiguous. Second, this ambiguity seems to depend on musical features, time scale, and genre. Furthermore, it is possible to tune current annotation evaluation metrics to better align with these perceptual differences. However, previous work has not directly analyzed the effects of hierarchical structure because the existing methods for comparing structural annotations are designed for "flat" descriptions, and do not readily generalize to hierarchical annotations. In this paper, we extend and generalize previous work on the evaluation of hierarchical descriptions of musical structure. We derive an evaluation metric which can compare hierarchical annotations holistically across multiple levels. sing this metric, we investigate inter-annotator agreement on the multilevel annotations of two different music corpora, investigate the influence of acoustic properties on hierarchical annotations, and evaluate existing hierarchical segmentation algorithms against the distribution of inter-annotator agreement.

  7. Evaluating Hierarchical Structure in Music Annotations

    Directory of Open Access Journals (Sweden)

    Brian McFee

    2017-08-01

    Full Text Available Music exhibits structure at multiple scales, ranging from motifs to large-scale functional components. When inferring the structure of a piece, different listeners may attend to different temporal scales, which can result in disagreements when they describe the same piece. In the field of music informatics research (MIR, it is common to use corpora annotated with structural boundaries at different levels. By quantifying disagreements between multiple annotators, previous research has yielded several insights relevant to the study of music cognition. First, annotators tend to agree when structural boundaries are ambiguous. Second, this ambiguity seems to depend on musical features, time scale, and genre. Furthermore, it is possible to tune current annotation evaluation metrics to better align with these perceptual differences. However, previous work has not directly analyzed the effects of hierarchical structure because the existing methods for comparing structural annotations are designed for “flat” descriptions, and do not readily generalize to hierarchical annotations. In this paper, we extend and generalize previous work on the evaluation of hierarchical descriptions of musical structure. We derive an evaluation metric which can compare hierarchical annotations holistically across multiple levels. sing this metric, we investigate inter-annotator agreement on the multilevel annotations of two different music corpora, investigate the influence of acoustic properties on hierarchical annotations, and evaluate existing hierarchical segmentation algorithms against the distribution of inter-annotator agreement.

  8. Synthesis of SmOHCO3 micro/nano particles from the coupling route of homogeneous precipitation with microemulsion

    Institute of Scientific and Technical Information of China (English)

    朱文庆; 瞿芳; 陈浩军; 李卓; 刘斌

    2014-01-01

    SmOHCO3micro/nano particles were prepared in water/oil (W/O) reverse microemulsion composed of cetyltrimethyl ammonium bromide (CTAB), n-octane, n-butanol, Sm(NO3)3·6H2O and urea aqueous solution by the coupling route of homogeneous precipitation with microemulsion. The nanoparticles were characterized and analyzed by X-ray powder diffraction (XRD), thermal gravimetric and differential thermal gravimetric analysis (TG-DTG), Fourier transform infrared absorption spectra (FT-IR) and scan-ning electron microscope (SEM). The results showed that the phase SmOHCO3 micro/nano particles was in agreement with pure or-thorhombic phase. The different morphologies of SmOHCO3 micro/nano particles with good monodispersity and size were obtained by regulating the reaction temperature and reaction time. Possible formation mechanisms of the morphological structure of SmO-HCO3 were proposed and discussed.

  9. Black silicon: substrate for laser 3D micro/nano-polymerization.

    Science.gov (United States)

    Žukauskas, Albertas; Malinauskas, Mangirdas; Kadys, Arūnas; Gervinskas, Gediminas; Seniutinas, Gediminas; Kandasamy, Sasikaran; Juodkazis, Saulius

    2013-03-25

    We demonstrate that black silicon (b-Si) made by dry plasma etching is a promising substrate for laser three-dimensional (3D) micro/nano-polymerization. High aspect ratio Si-needles, working as sacrificial support structures, have flexibility required to relax interface stresses between substrate and the polymerized micro-/nano- objects. Surface of b-Si can be made electrically conductive by metal deposition and, at the same time, can preserve low optical reflectivity beneficial for polymerization by direct laser writing. 3D laser polymerization usually performed at the irradiation conditions close to the dielectric breakdown is possible on non-reflective and not metallic surfaces. Here we show that low reflectivity and high metallic conductivity are not counter- exclusive properties for laser polymerization. Electrical conductivity of substrate and its permeability in liquids are promising for bio- and electroplating applications.

  10. Fabrication of Micro/Nano-textured Titanium Alloy Implant Surface and Its Inlfuence on Hydroxyapatite Coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rui; WAN Yi; AI Xing; MEN Bo; WANG Teng; LIU Zhanqiang; ZHANG Dong

    2016-01-01

    We put forward a protocol combining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant. Firstly, the operational parameters of the laser were optimized to obtain an optimum current. Secondly, the laser with the optimum operational parameters was used to fabricate micro pits. Thirdly, multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures. Finally, the bioactivity of the samples was measured in a simulated body lfuid. The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A. In addition, submicron and nanoscale structures, with 0.5-2 μm microgrooves and 10-20 nm nanopits, were superimposed on micro pits surface by multiple acid etching. There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface. This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation, which increased the bioactivity of implants.

  11. Plasmonics based micro/nano manufacturing

    Science.gov (United States)

    Garner, Quincy

    Since the advent of the Information Age, there has been an ever growing demand to continually shrink and reduce the cost of semiconductor products. To meet this demand, a great amount of research has been done to improve our current micro/nano manufacturing processes and develop the next generation of semiconductor fabrication techniques. High throughput, low cost, smaller features, high repeatability, and the simplification of the manufacturing processes are all targets that researchers continually strive for. To this day, there are no perfect systems capable of simultaneously achieving all of these targets. For this reason, much research time is spent improving and developing new techniques in hopes of developing a system that will incorporate all of these targets. While there are numerous techniques being investigated and developed every year, one of the most promising areas of research that may one day be capable of achieving our desired targets is plasmonics. Plasmonics, or the study of the free electron oscillations in metals, is the driving phenomena in the applications reported in this paper. In chapter 2, the formation of ordered gold nanoparticles on a silicon substrate through the use of energetic surface plasmons is reported. Utilizing a gold/alumina nano-hole antenna and 1064 nm Nd:YAG laser system, semi-periodic gold nanoparticles were deposited onto the surface of a silicon substrate. The novel technique is simpler, faster, and safer than any known gold nanoparticle deposition technique reported in literature. The implementation of this technique has potential wide-ranging applications in photovoltaic cells, medical products, and many others. In chapter 3, a low cost lithography technique utilizing surface plasmons is reported. In this technique, a plasmonic photomask is created by coating a pre-made porous alumina membrane with a thin aluminum layer. A coherent, 337 nm UV laser source is used to expose the photomask and excite surface plasmons along

  12. Selected Topics in MicroNano-robotics for Biomedical Applications

    CERN Document Server

    2013-01-01

    Selected Topics in Micro/Nano-robotics for Biomedical Applications features a system approach and incorporates modern methodologies in autonomous mobile robots for programmable and controllable micro/nano-robots aiming at biomedical applications. The book provides chapters of instructional materials and cutting-edge research results in micro/nanorobotics for biomedical applications. The book presents new sensing technology on nanofibers, new power supply techniques including miniature fuel cells and energy harvesting devices, and manipulation techniques including AFM-based nano-robotic manipulation, robot-aided optical tweezers, and robot-assisted catheter surgery systems. It also contains case studies on using micro/nano-robots in biomedical environments and in biomedicine, as well as a design example to conceptually develop a Vitamin-pill sized robot to enter human’s gastrointestinal tract. Each chapter covers a different topic of the highly interdisciplinary area. Bring together the selected topics into ...

  13. Quantum transport through hierarchical structures.

    Science.gov (United States)

    Boettcher, S; Varghese, C; Novotny, M A

    2011-04-01

    The transport of quantum electrons through hierarchical lattices is of interest because such lattices have some properties of both regular lattices and random systems. We calculate the electron transmission as a function of energy in the tight-binding approximation for two related Hanoi networks. HN3 is a Hanoi network with every site having three bonds. HN5 has additional bonds added to HN3 to make the average number of bonds per site equal to five. We present a renormalization group approach to solve the matrix equation involved in this quantum transport calculation. We observe band gaps in HN3, while no such band gaps are observed in linear networks or in HN5. We provide a detailed scaling analysis near the edges of these band gaps.

  14. Investigating the BSA protein adsorption and bacterial adhesion of Al-alloy surfaces after creating a hierarchical (micro/nano) superhydrophobic structure.

    Science.gov (United States)

    Moazzam, Parisa; Razmjou, Amir; Golabi, Mohsen; Shokri, Dariush; Landarani-Isfahani, Amir

    2016-09-01

    Bacterial adhesion and subsequent biofilm formation on metals such as aluminum (Al) alloys lead to serious issues in biomedical and industrial fields from both an economical and health perspective. Here, we showed that a careful manipulation of Al surface characteristics via a facile two-steps superhydrophobic modification can provide not only biocompatibility and an ability to control protein adsorption and bacterial adhesion, but also address the issue of apparent long-term toxicity of Al-alloys. To find out the roles of surface characteristics, surface modification and protein adsorption on microbial adhesion and biofilm formation, the surfaces were systematically characterized by SEM, EDX, XPS, AFM, FTIR, water contact angle (WCA) goniometry, surface free energy (SFE) measurement, MTT, Bradford, Lowry and microtiter plate assays and also flow-cytometry and potentiostat analyses. Results showed that WCA and SFE changed from 70° to 163° and 36.3 to 0.13 mN m(-1) , respectively. The stable and durable modification led to a substantial reduction in static/dynamic BSA adsorption. The effect of such a treatment on the biofilm formation was analyzed by using three different bacteria of Pseudomonas aeruginosa, Staphylococcus epidermidis, and Staphylococcus aureus. The microtiter plate assay and flow cytometry analysis showed that the modification not only could substantially reduce the bacterial adhesion but this biofouling resistance is independent of bacterium type. An excellent cell viability after exposure of HeLa cells to waters incubated with the modified samples was observed. Finally, the corrosion rate reduced sharply from 856.6 to 0.119 MPY after superhydrophobic modifications, which is an excellent stable corrosion inhibition property. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2220-2233, 2016.

  15. The fabrication and hydrophobic property of micro-nano patterned surface on magnesium alloy using combined sparking sculpture and etching route

    Science.gov (United States)

    Wu, Yunfeng; Wang, Yaming; Liu, Hao; Liu, Yan; Guo, Lixin; Jia, Dechang; Ouyang, Jiahu; Zhou, Yu

    2016-12-01

    Magnesium alloy with micro-nano structure roughness surface, can serve as the loading reservoirs of medicine capsule and industrial lubricating oil, or mimic 'lotus leaf' hydrophobic surface, having the potential applications in medical implants, automobile, aerospace and electronic products, etc. Herein, we propose a novel strategy to design a micro-nano structure roughness surface on magnesium alloy using combined microarc sparking sculpture and etching in CrO3 aqueous solution. A hydrophobic surface (as an applied example) was further fabricated by chemical decorating on the obtained patterned magnesium alloy surface to enhance the corrosion resistance. The results show that the combined micro-nano structure of 7-9 μm diameter big pores insetting with nano-scale fine pores was duplicated after etched the sparking sculptured 'over growth' oxide regions towards the magnesium substrate. The micro-nano structure surface was chemically decorated using AgNO3 and stearic acid, which enables the contact angle increased from 60° to 146.8°. The increasing contact angle is mainly attributed to the micro-nano structure and the chemical composition. The hydrophobic surface of magnesium alloy improved the corrosion potential from -1.521 V of the bare magnesium to -1.274 V. Generally, the sparking sculpture and then etching route demonstrates a low-cost, high-efficacy method to fabricate a micro-nano structure hydrophobic surface on magnesium alloy. Furthermore, our research on the creating of micro-nano structure roughness surface and the hydrophobic treatment can be easily extended to the other metal materials.

  16. Hierarchical Neural Network Structures for Phoneme Recognition

    CERN Document Server

    Vasquez, Daniel; Minker, Wolfgang

    2013-01-01

    In this book, hierarchical structures based on neural networks are investigated for automatic speech recognition. These structures are evaluated on the phoneme recognition task where a  Hybrid Hidden Markov Model/Artificial Neural Network paradigm is used. The baseline hierarchical scheme consists of two levels each which is based on a Multilayered Perceptron. Additionally, the output of the first level serves as a second level input. The computational speed of the phoneme recognizer can be substantially increased by removing redundant information still contained at the first level output. Several techniques based on temporal and phonetic criteria have been investigated to remove this redundant information. The computational time could be reduced by 57% whilst keeping the system accuracy comparable to the baseline hierarchical approach.

  17. Hierarchical structure of nanofibers by bubbfil spinning

    Directory of Open Access Journals (Sweden)

    Liu Chang

    2015-01-01

    Full Text Available A polymer bubble is easy to be broken under a small external force, various different fragments are formed, which can be produced to different morphologies of products including nanofibers and plate-like strip. Polyvinyl-alcohol/honey solution is used in the experiment to show hierarchical structure by the bubbfil spinning.

  18. Design of Hierarchical Structures for Synchronized Deformations

    Science.gov (United States)

    Seifi, Hamed; Javan, Anooshe Rezaee; Ghaedizadeh, Arash; Shen, Jianhu; Xu, Shanqing; Xie, Yi Min

    2017-01-01

    In this paper we propose a general method for creating a new type of hierarchical structures at any level in both 2D and 3D. A simple rule based on a rotate-and-mirror procedure is introduced to achieve multi-level hierarchies. These new hierarchical structures have remarkably few degrees of freedom compared to existing designs by other methods. More importantly, these structures exhibit synchronized motions during opening or closure, resulting in uniform and easily-controllable deformations. Furthermore, a simple analytical formula is found which can be used to avoid collision of units of the structure during the closing process. The novel design concept is verified by mathematical analyses, computational simulations and physical experiments.

  19. Micro/nano structured coatings of light alloys by cold spray for surface protection and repair of high value-added components: State of the art; Recubrimientos micro/nanoestructurados de aleaciones ligeras mediante proyeccion fria para la proteccion y reparacion de componentes de elevado valor anadido: Estado del arte

    Energy Technology Data Exchange (ETDEWEB)

    Bedoya, J.; Cinca, N.; Guilemany, J. M.

    2013-09-01

    The Cold Gas Spray - CGS technique has greatly attracted the attention of the researchers in the last decade due to advantages compared to other conventional thermal spray processes. It presents outstanding characteristics such as high density coatings and absence of thermal degradation (oxidation or phase transformation). In addition, CGS is an efficient and green technology. This paper presents a bibliographic review related to micro/nano structured aluminium-based coatings of by CGS on light alloy substrates. It provides an overview of the feasibility of using the Cold Gas Spray as a technique for the protection, recovery and repair of high value-added components, especially those made of light alloys (aluminium and magnesium base) which, by their low density and mechanical properties, are widely used in several industrial sectors such as transport, aerospace and power generation. (Author)

  20. Electronic Properties in a Hierarchical Multilayer Structure

    Institute of Scientific and Technical Information of China (English)

    ZHU Chen-Ping; XIONG Shi-Jie

    2001-01-01

    We investigate electronic properties of a hierarchical multilayer structure consisting of stacking of barriers and wells. The structure is formed in a sequence of generations, each of which is constructed with the same pattern but with the previous generation as the basic building blocks. We calculate the transmission spectrum which shows the multifractal behavior for systems with large generation index. From the analysis of the average resistivity and the multifractal structure of the wavefunctions, we show that there exist different types of states exhibiting extended, localized and intermediate characteristics. The degree of localization is sensitive to the variation of the structural parameters.Suggestion of the possible experimental realization is discussed.

  1. Hierarchical community structure in complex (social) networks

    CERN Document Server

    Massaro, Emanuele

    2014-01-01

    The investigation of community structure in networks is a task of great importance in many disciplines, namely physics, sociology, biology and computer science where systems are often represented as graphs. One of the challenges is to find local communities from a local viewpoint in a graph without global information in order to reproduce the subjective hierarchical vision for each vertex. In this paper we present the improvement of an information dynamics algorithm in which the label propagation of nodes is based on the Markovian flow of information in the network under cognitive-inspired constraints \\cite{Massaro2012}. In this framework we have introduced two more complex heuristics that allow the algorithm to detect the multi-resolution hierarchical community structure of networks from a source vertex or communities adopting fixed values of model's parameters. Experimental results show that the proposed methods are efficient and well-behaved in both real-world and synthetic networks.

  2. Hierarchical mutual information for the comparison of hierarchical community structures in complex networks

    CERN Document Server

    Perotti, Juan Ignacio; Caldarelli, Guido

    2015-01-01

    The quest for a quantitative characterization of community and modular structure of complex networks produced a variety of methods and algorithms to classify different networks. However, it is not clear if such methods provide consistent, robust and meaningful results when considering hierarchies as a whole. Part of the problem is the lack of a similarity measure for the comparison of hierarchical community structures. In this work we give a contribution by introducing the {\\it hierarchical mutual information}, which is a generalization of the traditional mutual information, and allows to compare hierarchical partitions and hierarchical community structures. The {\\it normalized} version of the hierarchical mutual information should behave analogously to the traditional normalized mutual information. Here, the correct behavior of the hierarchical mutual information is corroborated on an extensive battery of numerical experiments. The experiments are performed on artificial hierarchies, and on the hierarchical ...

  3. Durable polyorganosiloxane superhydrophobic films with a hierarchical structure by sol-gel and heat treatment method

    Science.gov (United States)

    Jiang, Zhenlin; Fang, Shuying; Wang, Chaosheng; Wang, Huaping; Ji, Chengchang

    2016-12-01

    For a surface to be superhydrophobic a combination of surface roughness and low surface energy is required. In this study, polyorganosiloxane superhydrophobic surfaces were fabricated using a sol-gel and heat treatment process followed by coating with a nanosilica (SiO2) sol and organosiloxane 1, 1, 1, 3, 5, 5, 5-heptamethyl-3-[2-(trimethoxysilyl)ethyl]-trisiloxane (β-HPEOs). The nano-structure was superimposed using self-assembled, surface-modified silica nanoparticles, forming two-dimensional hierarchical structures. The water contact angle (WCA) of polyorganosiloxane superhydrophobic surface was 143.7 ± 0.6°, which was further increased to 156.7 ± 1.1° with water angle hysteresis of 2.5 ± 0.6° by superimposing nanoparticles using a heat treatment process. An analytical characterization of the surface revealed that the nano-silica and polyorganosiloxane formed a micro/nano structure on the films and the wetting behaviour of the films changed from hydrophilic to superhydrophobic. The WCA of these films were 143.7 ± 0.6° and at heat treatment temperatures of less than 400 °C, the WCA increased from 144.5 ± 0.7° to 156.7 ± 1.1°. The prepared superhydrophobic films were stable even after heat treatment at 430 °C for 30 min and their superhydrophobicity was durable for more than 120 days. The effects of heat treatment process on the surface chemistry structure, wettability and morphology of the polyorganosiloxane superhydrophobic films were investigated in detail. The results indicated that the stability of the chemical structure was required to yield a thermally-stable superhydrophobic surface.

  4. Hierarchically micro-patterned nanofibrous scaffolds with a nanosized bio-glass surface for accelerating wound healing

    Science.gov (United States)

    Xu, He; Lv, Fang; Zhang, Yali; Yi, Zhengfang; Ke, Qinfei; Wu, Chengtie; Liu, Mingyao; Chang, Jiang

    2015-11-01

    A composite scaffold with a controlled micro-pattern, nano-sized fiber matrix and surface-modified nanobioglass component was successfully prepared for skin wound healing by combining the patterning electrospinning with pulsed laser deposition strategies, and the hierarchical micro/nano structures and nano-sized bioglass in the scaffolds could synergistically improve the efficiency and re-epithelialization of wound healing.A composite scaffold with a controlled micro-pattern, nano-sized fiber matrix and surface-modified nanobioglass component was successfully prepared for skin wound healing by combining the patterning electrospinning with pulsed laser deposition strategies, and the hierarchical micro/nano structures and nano-sized bioglass in the scaffolds could synergistically improve the efficiency and re-epithelialization of wound healing. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04802h

  5. Advanced control of piezoelectric micro-nano-positioning systems

    CERN Document Server

    Xu, Qingsong

    2016-01-01

    This book explores emerging methods and algorithms that enable precise control of micro-/nano-positioning systems. The text describes three control strategies: hysteresis-model-based feedforward control and hysteresis-model-free feedback control based on and free from state observation. Each paradigm receives dedicated attention within a particular part of the text. Readers are shown how to design, validate and apply a variety of new control approaches in micromanipulation: hysteresis modelling, discrete-time sliding-mode control and model-reference adaptive control. Experimental results are provided throughout and build up to a detailed treatment of practical applications in the fourth part of the book. The applications focus on control of piezoelectric grippers. Advanced Control of Piezoelectric Micro-/Nano-Positioning Systems will assist academic researchers and practising control and mechatronics engineers interested in suppressing sources of nonlinearity such as hysteresis and drift when combining positi...

  6. Controlling nitrogen migration through micro-nano networks

    OpenAIRE

    Cai, Dongqing; Wu, Zhengyan; Jiang, Jiang; Wu, Yuejin; Feng, Huiyun; Brown, Ian G.; Chu, Paul K.; Yu, Zengliang

    2014-01-01

    Nitrogen fertilizer unabsorbed by crops eventually discharges into the environment through runoff, leaching and volatilization, resulting in three-dimensional (3D) pollution spanning from underground into space. Here we describe an approach for controlling nitrogen loss, developed using loss control fertilizer (LCF) prepared by adding modified natural nanoclay (attapulgite) to traditional fertilizer. In the aqueous phase, LCF self-assembles to form 3D micro/nano networks via hydrogen bonds an...

  7. Additive Manufacturing of Hierarchical Porous Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division. Polymers and Coatings

    2016-08-30

    Additive manufacturing has become a tool of choice for the development of customizable components. Developments in this technology have led to a powerful array of printers that t serve a variety of needs. However, resin development plays a crucial role in leading the technology forward. This paper addresses the development and application of printing hierarchical porous structures. Beginning with the development of a porous scaffold, which can be functionalized with a variety of materials, and concluding with customized resins for metal, ceramic, and carbon structures.

  8. Micro-nano-biosystems: An overview of European research.

    Science.gov (United States)

    Lymberis, Andreas

    2010-06-01

    New developments in science, technologies and applications are blurring the boundaries between information and communications technology (ICT), micro-nano systems and life sciences, e.g. through miniaturisation and the ability to manipulate matter at the atomic scale and to interface live and man-made systems. Interdisciplinary research towards integrated systems and their applications based on emerging convergence of information & communication technologies, micro-nano and bio technologies is expected to have a direct influence on healthcare, ageing population and well being. Micro-Nano-Bio Systems (MNBS) research and development activities under the European Union's R&D Programs, Information & Communication Technologies priority address miniaturised, smart and integrated systems for in-vitro testing e.g. lab-on-chips and systems interacting with the human e.g. autonomous implants, endoscopic capsules and robotics for minimally invasive surgery. The MNBS group involves hundreds of key public and private international organisations working on system development and validation in diverse applications such as cancer detection and therapy follow-up, minimally invasive surgery, capsular endocsopy, wearable biochemical monitoring and repairing of vital functions with active implant devices. The paper presents MNBS rationale and activities, discusses key research and innovation challenges and proposes R&D directions to achieve the expected impact on healthcare and quality of life.

  9. A displacement spindle in a micro/nano level

    Science.gov (United States)

    Fan, Kuang-Chao; Lai, Zi-Fa; Wu, Peitsung; Chen, Yung-Chang; Chen, Yejin; Jäger, Gerd

    2007-06-01

    This paper presents two micro/nano level displacement sensors, which consist of a mini LDGI (linear diffraction grating interferometer) and a focus probe. These two sensors are integrated into the spindle system of a micro/nano-CMM. This micro/nano spindle system is fixed on a rectangular granite bridge to achieve the z-axis function. The motion of the spindle is driven by an ultrasonic motor on a precision cross-roller slide. Its displacement is fed back by the LDGI. A DVD pick-up head is modified with its S-curve principle as the non-contact focus probe. Mounting the probe onto the spindle head, it is possible to achieve a large displacement and nanoresolution measuring spindle system with a feedback nanomotion control scheme. After accuracy calibration and error compensation, the spindle motion to 10 mm can perform 10 nm positioning accuracy and 30 nm measurement accuracy. Experiments on some ultraprecision profiles have shown the capability of this spindle system.

  10. The Synergistic Effects of the Micro and Nano Particles in Micro-nano Composites on Enhancing the Resistance to Electrical Tree Degradation.

    Science.gov (United States)

    Wang, Wenxuan; Yang, Ying

    2017-08-17

    A new method of increasing the durability and reliability of polymer dielectrics has been proposed by designing a composite structure of the micro and nano particles. The synergistic effects of the micro particles and nano particles are found to enhance the resistance to electrical tree and extend the lifetime of polymer dielectrics for insulations. Epoxy loaded with the micro and nano SiO2 particles at different concentrations are prepared as micro-nano composites. The micro particles show the blocking effects on the electrical tree channel and the interfaces of the nano particles lead to the inhibiting effects on the tree inception and propagation. The lifetime of the micro-nano composite samples in the experiments extends to 4 times of the neat epoxy. The new type of micro-nano composites can be widely applied in future electronic and electrical energy areas.

  11. The hierarchical structure of chemical engineering

    Institute of Scientific and Technical Information of China (English)

    Mooson; KWAUK

    2007-01-01

    Around the turn of the present century,scholars began to recognize chemical engineering as a com-plex system,and have been searching for a convenient point of entry for refreshing its knowledge base.From our study of the dynamic structures of dispersed particles in fluidization and the resultingmulti-scale method,we have been attempting to extend our findings to structures prevailing in othermultiphase systems as well as in the burgeoning industries producing functional materials.Chemicalengineering itself is hierarchically structured.Besides structures based on space and time,such hier-archy could be built from ChE history scaled according to science content,or from ChE operation ac-cording to the expenditure of manpower and capital investment.

  12. The hierarchical structure of chemical engineering

    Institute of Scientific and Technical Information of China (English)

    Mooson KWAUK

    2007-01-01

    Around the turn of the present century, scholars began to recognize chemical engineering as a complex system, and have been searching for a convenient point of entry for refreshing its knowledge base. From our study of the dynamic structures of dispersed particles in fluidization and the resulting multi-scale method, we have been attempting to extend our findings to structures prevailing in other multiphase systems as well as in the burgeoning industries producing functional materials. Chemical engineering itself is hierarchically structured. Besides structures based on space and time, such hierarchy could be built from ChE history scaled according to science content, or from ChE operation according to the expenditure of manpower and capital investment.

  13. Micro/nano-particle decorated metal wire for cutting soft matter

    Science.gov (United States)

    Zhang, Wei; Feng, Liang-liang; Wu, Fan; Zhang, Run-run; Wu, Cheng-wei

    2016-09-01

    To cut soft materials such as biological tissues with minimal damage and reduced positional error is highly desired in medical surgery and biomechanics. After years of natural selection and evolution, mosquitoes have acquired the ability to insert their proboscises into human skin with astonishingly tiny forces. This can be associated with the unique structure of their proboscises, with micro/nano sawteeth, and the distinctive insertion manner: high frequency reciprocating saw cutting. Inspired by these, this communication describes the successful implantation of metal oxide particles onto molybdenum wire surfaces through a sol-calcination process, to form a biomimetic sawblade with a high density of micro/nano saw teeth, where the acidification is essential in terms of generating active anchoring sites on the wire. When used as a sawblade in conjunction with reciprocating action to cut the viscoelastic gel, both the cut-in force and cut-in displacement could be decreased substantially. The cutting speed and frequency of reciprocating action are important operating parameters influencing cut-in force.

  14. Sense and avoid radar for micro/nano robots

    Science.gov (United States)

    Molchanov, Pavlo A.; Asmolova, Olha

    2014-10-01

    Revolutionary new fly eye radar sensor technologies based on an array of directional antennas is eliminating the need for a mechanical scanning antenna or complicated phase processor. Proposed sense and avoid radar based on fly eye radar technology can be very small, provides continuous surveillance of entire sky (360 degree by azimuth and elevation) and can be applied for separate or swarm of micro/nano UAS or UGS. Monopulse technology increases bearing accuracy several folds and radar can be multi-functional, multi-frequency. Fly eye micro-radars are inexpensive, can be expendable. Prototype of sense and avoid radar with two directional antennas has been designed and bench tested.

  15. Micro Nano PMP (Product-Method-Process) Graduate Course

    DEFF Research Database (Denmark)

    De Grave, Arnaud; Hansen, Hans Nørgaard

    2005-01-01

    This paper describes a framework for teaching in the development (design and manufacture) of products in the micro / nano scale in the Department of Manufacturing Engineering and Management (IPL) at the Technical University of Denmark (DTU). The training of students in this field involves both...... lectures and practical works, and covers aspects such as methods and tools, manufacturing techniques and product-oriented studies. Students then apply the methods and tools in a collaborative design, manufacture and testing process of a real micro fluidic application. The specificities of micro products...

  16. Micro Nano PMP (Product-Method-Process) Graduate Course

    DEFF Research Database (Denmark)

    De Grave, Arnaud; Hansen, Hans Nørgaard

    2005-01-01

    This paper describes a framework for teaching in the development (design and manufacture) of products in the micro / nano scale in the Department of Manufacturing Engineering and Management (IPL) at the Technical University of Denmark (DTU). The training of students in this field involves both...... lectures and practical works, and covers aspects such as methods and tools, manufacturing techniques and product-oriented studies. Students then apply the methods and tools in a collaborative design, manufacture and testing process of a real micro fluidic application. The specificities of micro products...

  17. Hierarchical structures in fully developed turbulence

    Science.gov (United States)

    Liu, Li

    Analysis of the probability density functions (PDFs) of the velocity increment dvl and of their deformation is used to reveal the statistical structure of the intermittent energy cascade dynamics of turbulence. By analyzing a series of turbulent data sets including that of an experiment of fully developed low temperature helium turbulent gas flow (Belin, Tabeling, & Willaime, Physica D 93, 52, 1996), of a three-dimensional isotropic Navier-Stokes simulation with a resolution of 2563 (Cao, Chen, & She, Phys. Rev. Lett. 76, 3711, 1996) and of a GOY shell model simulation (Leveque & She, Phys. Rev. E 55, 1997) of a very big sample size (up to 5 billions), the validity of the Hierarchical Structure model (She & Leveque, Phys. Rev. Lett. 72, 366, 1994) for the inertial-range is firmly demonstrated. Furthermore, it is shown that parameters in the Hierarchical Structure model can be reliably measured and used to characterize the cascade process. The physical interpretations of the parameters then allow to describe differential changes in different turbulent systems so as to address non-universal features of turbulent systems. It is proposed that the above study provides a framework for the study of non-homogeneous turbulence. A convergence study of moments and scaling exponents is also carried out with detailed analysis of effects of finite statistical sample size. A quantity Pmin is introduced to characterize the resolution of a PDF, and hence the sample size. The fact that any reported scaling exponent depends on the PDF resolution suggests that the validation (or rejection) of a model of turbulence needs to carry out a resolution dependence analysis on its scaling prediction.

  18. Crack Propagation in Bamboo's Hierarchical Cellular Structure

    Science.gov (United States)

    Habibi, Meisam K.; Lu, Yang

    2014-07-01

    Bamboo, as a natural hierarchical cellular material, exhibits remarkable mechanical properties including excellent flexibility and fracture toughness. As far as bamboo as a functionally graded bio-composite is concerned, the interactions of different constituents (bamboo fibers; parenchyma cells; and vessels.) alongside their corresponding interfacial areas with a developed crack should be of high significance. Here, by using multi-scale mechanical characterizations coupled with advanced environmental electron microscopy (ESEM), we unambiguously show that fibers' interfacial areas along with parenchyma cells' boundaries were preferred routes for crack growth in both radial and longitudinal directions. Irrespective of the honeycomb structure of fibers along with cellular configuration of parenchyma ground, the hollow vessels within bamboo culm affected the crack propagation too, by crack deflection or crack-tip energy dissipation. It is expected that the tortuous crack propagation mode exhibited in the present study could be applicable to other cellular natural materials as well.

  19. Pulse electrochemical meso/micro/nano ultraprecision machining technology.

    Science.gov (United States)

    Lee, Jeong Min; Kim, Young Bin; Park, Jeong Woo

    2013-11-01

    This study demonstrated meso/micro/nano-ultraprecision machining through electrochemical reactions using intermittent DC pulses. The experiment focused on two machining methods: (1) pulse electrochemical polishing (PECP) of stainless steel, and (2) pulse electrochemical nano-patterning (PECNP) on a silicon (Si) surface, using atomic force microscopy (AFM) for fabrication. The dissolution reaction at the stainless steel surface following PECP produced a very clean, smooth workpiece. The advantages of the PECP process included improvements in corrosion resistance, deburring of the sample surface, and removal of hydrogen from the stainless steel surface as verified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS). In PECNP, the electrochemical reaction generated within water molecules produced nanoscale oxide textures on a Si surface. Scanning probe microscopy (SPM) was used to evaluate nanoscale-pattern processing on a Si wafer surface produced by AFM-PECNP For both processes using pulse electrochemical reactions, three-dimensional (3-D) measurements and AFM were used to investigate the changes on the machined surfaces. Preliminary results indicated the potential for advancing surface polishing techniques and localized micro/nano-texturing technology using PECP and PECNP processes.

  20. Hierarchical structure and biomineralization in cricket tooth

    CERN Document Server

    Xing, Xueqing; Cai, Quan; Mo, Guang; Du, Rong; Chen, Zhongjun; Wu, Zhonghua

    2012-01-01

    Cricket is a truculent insect with stiff and sharp teeth as a fighting weapon. The structure and possible biomineralization of the cricket teeth are always interested. Synchrotron radiation X-ray fluorescence, X-ray diffraction and small angle X-ray scattering techniques were used to probe the element distribution, possible crystalline structures and size distribution of scatterers in cricket teeth. Scanning electron microscope was used to observe the nanoscaled structure. The results demonstrate that Zn is the main heavy element in cricket teeth. The surface of the cricket teeth has a crystalline compound like ZnFe2(AsO4)2(OH)2(H2O)4. While, the interior of the teeth has a crystalline compound like ZnCl2, which is from the biomineralization. The ZnCl2-like biomineral forms nanoscaled microfibrils and their axial direction points at the top of tooth cusp. The microfibrils aggregate random into intermediate filaments, forming a hierarchical structure. A sketch map of the cricket tooth cusp was proposed and a d...

  1. Hierarchical structure of moral stages assessed by a sorting task

    NARCIS (Netherlands)

    Boom, J.; Brugman, D.; Van der Heijden, P.G.M.

    2001-01-01

    Following criticism of Kohlberg’s theory of moral judgment, an empirical re-examination of hierarchical stage structure was desirable. Utilizing Piaget’s concept of reflective abstraction as a basis, the hierarchical stage structure was investigated using a new method. Study participants (553 Dutch

  2. Wettability transition of plasma-treated polystyrene micro/nano pillars-aligned patterns

    Directory of Open Access Journals (Sweden)

    2010-12-01

    Full Text Available This paper reports the wettability transition of plasma-treated polystyrene (PS micro/nano pillars-aligned patterns. The micro/nano pillars were prepared using hot embossing on silicon microporous template and alumina nanoporous template, which were fabricated by ultraviolet (UV lithography and inductive coupled plasma (ICP etching, and two-step anodic oxidation, respectively. The results indicate that the combination of micro/nano patterning and plasma irradiation can easily regulate wettabilities of PS surfaces, i.e. from hydrophilicity to hydrophobicity, or from hydrophobicity to superhydrophilicity. During the wettability transition from hydrophobicity to hydrophilicity there is only mild hydrophilicity loss. After plasma irradiation, moreover, the wettability of PS micro/nano pillars-aligned patterns is more stable than that of flat PS surfaces. The observed wettability transition and wettability stability of PS micro/nano pillars-aligned patterns are new phenomena, which may have potential in creating programmable functional polymer surfaces.

  3. Micro/nano analysis of tooth microstructures by Focused Ion Beam (FIB cross-sectioning

    Directory of Open Access Journals (Sweden)

    Meltem Sezen

    2017-04-01

    Full Text Available Since dental structures are hard and fragile, cross-sectioning of these materials using ultramicrotomy and other techniques and following micro and nano analysis cause problems. The use of FIB-SEM dual beam platforms is the most convenient solution for investigating the microstructures, site-specifically and in certain geometries. Dual beam platforms allow for imaging at high magnifications and resolutions and simultaneous elemental analysis. In this study, the micro/nano-structural and chemical differences were revealed in dentin and enamel samples. The investigation of dental tissues having different morphologies and chemical components by ion-cross-sectioning is important for the use of FIB-SEM platforms in dentistry in Turkey.

  4. Automatic layout of structured hierarchical reports.

    Science.gov (United States)

    Bakke, Eirik; Karger, David R; Miller, Robert C

    2013-12-01

    Domain-specific database applications tend to contain a sizable number of table-, form-, and report-style views that must each be designed and maintained by a software developer. A significant part of this job is the necessary tweaking of low-level presentation details such as label placements, text field dimensions, list or table styles, and so on. In this paper, we present a horizontally constrained layout management algorithm that automates the display of structured hierarchical data using the traditional visual idioms of hand-designed database UIs: tables, multi-column forms, and outline-style indented lists. We compare our system with pure outline and nested table layouts with respect to space efficiency and readability, the latter with an online user study on 27 subjects. Our layouts are 3.9 and 1.6 times more compact on average than outline layouts and horizontally unconstrained table layouts, respectively, and are as readable as table layouts even for large datasets.

  5. Controlling nitrogen migration through micro-nano networks

    Science.gov (United States)

    Cai, Dongqing; Wu, Zhengyan; Jiang, Jiang; Wu, Yuejin; Feng, Huiyun; Brown, Ian G.; Chu, Paul K.; Yu, Zengliang

    2014-01-01

    Nitrogen fertilizer unabsorbed by crops eventually discharges into the environment through runoff, leaching and volatilization, resulting in three-dimensional (3D) pollution spanning from underground into space. Here we describe an approach for controlling nitrogen loss, developed using loss control fertilizer (LCF) prepared by adding modified natural nanoclay (attapulgite) to traditional fertilizer. In the aqueous phase, LCF self-assembles to form 3D micro/nano networks via hydrogen bonds and other weak interactions, obtaining a higher nitrogen spatial scale so that it is retained by a soil filtering layer. Thus nitrogen loss is reduced and sufficient nutrition for crops is supplied, while the pollution risk of the fertilizer is substantially lowered. As such, self-fabrication of nano-material was used to manipulate the nitrogen spatial scale, which provides a novel and promising approach for the research and control of the migration of other micro-scaled pollutants in environmental medium.

  6. Hierarchical Data Structures, Institutional Research, and Multilevel Modeling

    Science.gov (United States)

    O'Connell, Ann A.; Reed, Sandra J.

    2012-01-01

    Multilevel modeling (MLM), also referred to as hierarchical linear modeling (HLM) or mixed models, provides a powerful analytical framework through which to study colleges and universities and their impact on students. Due to the natural hierarchical structure of data obtained from students or faculty in colleges and universities, MLM offers many…

  7. Cortical tracking of hierarchical linguistic structures in connected speech.

    Science.gov (United States)

    Ding, Nai; Melloni, Lucia; Zhang, Hang; Tian, Xing; Poeppel, David

    2016-01-01

    The most critical attribute of human language is its unbounded combinatorial nature: smaller elements can be combined into larger structures on the basis of a grammatical system, resulting in a hierarchy of linguistic units, such as words, phrases and sentences. Mentally parsing and representing such structures, however, poses challenges for speech comprehension. In speech, hierarchical linguistic structures do not have boundaries that are clearly defined by acoustic cues and must therefore be internally and incrementally constructed during comprehension. We found that, during listening to connected speech, cortical activity of different timescales concurrently tracked the time course of abstract linguistic structures at different hierarchical levels, such as words, phrases and sentences. Notably, the neural tracking of hierarchical linguistic structures was dissociated from the encoding of acoustic cues and from the predictability of incoming words. Our results indicate that a hierarchy of neural processing timescales underlies grammar-based internal construction of hierarchical linguistic structure.

  8. Mechanically robust superhydrophobicity on hierarchically structured Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xiu Yonghao; Hess, Dennis W [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0100 (United States); Liu Yan; Wong, C P, E-mail: dennis.hess@chbe.gatech.edu, E-mail: cp.wong@mse.gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, GA 30332-0245 (United States)

    2010-04-16

    Improvement of the robustness of superhydrophobic surfaces is critical in order to achieve commercial applications of these surfaces in such diverse areas as self-cleaning, water repellency and corrosion resistance. In this study, the mechanical robustness of superhydrophobic surfaces was evaluated on hierarchically structured silicon surfaces. The effect of two-scale hierarchical structures on robustness was investigated using an abrasion test and the results compared to those of superhydrophobic surfaces fabricated from polymeric materials and from silicon that contains only nanostructures. Unlike the polymeric and nanostructure-only surfaces, the hierarchical structures retained superhydrophobic behavior after mechanical abrasion.

  9. Self-assembled biomimetic superhydrophobic hierarchical arrays.

    Science.gov (United States)

    Yang, Hongta; Dou, Xuan; Fang, Yin; Jiang, Peng

    2013-09-01

    Here, we report a simple and inexpensive bottom-up technology for fabricating superhydrophobic coatings with hierarchical micro-/nano-structures, which are inspired by the binary periodic structure found on the superhydrophobic compound eyes of some insects (e.g., mosquitoes and moths). Binary colloidal arrays consisting of exemplary large (4 and 30 μm) and small (300 nm) silica spheres are first assembled by a scalable Langmuir-Blodgett (LB) technology in a layer-by-layer manner. After surface modification with fluorosilanes, the self-assembled hierarchical particle arrays become superhydrophobic with an apparent water contact angle (CA) larger than 150°. The throughput of the resulting superhydrophobic coatings with hierarchical structures can be significantly improved by templating the binary periodic structures of the LB-assembled colloidal arrays into UV-curable fluoropolymers by a soft lithography approach. Superhydrophobic perfluoroether acrylate hierarchical arrays with large CAs and small CA hysteresis can be faithfully replicated onto various substrates. Both experiments and theoretical calculations based on the Cassie's dewetting model demonstrate the importance of the hierarchical structure in achieving the final superhydrophobic surface states. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Progress of SERS Based on Nano-particles/Coupled Metalic Structure between Nano-particles and Film with Micro-nano Structure%金属纳米颗粒/微纳结构金属膜增强拉曼研究进展

    Institute of Scientific and Technical Information of China (English)

    易明芳

    2014-01-01

    被称为“指纹谱”的分子拉曼谱及拉曼散射成像在生物及化学单分子识别领域具有重要应用。问题的关键是分子的拉曼散射截面小,利用金属纳米颗粒(LSP)局域场增强特性及其与金属膜(SPP)相互作用可产生比 LSP ( SPP)更强的局域场及尖角结构金属纳米颗粒的“热点天线”效应,可实现单分子拉曼信号的激发与辐射双共振增强效应。本文综述有关金属纳米颗粒和微纳结构金属膜相耦合增强分子拉曼信号的研究进展。%The “fingerprint” Raman spectra have important application in the field of chemistry or biotechnology which makes it possible to visualize individual molecules with chemical recognition .The key question is that the Raman scattering cross section of a single molecule is very small.The localized field enhancements of the surface plasmon polaritons is the physical basement of surface enhanced Raman spectra( SERS) .The hybrid plasmons which is a kind of coupling electric field between the LSP and SPP will produce stronger electric field than the LSP or SPP alone and the nano-metal particles with sharp corners structure can produce"hot spot"effect.It can realize the double-resonance enhancement for both Raman excitation and Raman emission.This paper will summarize the progress of SERS based on nano-particles/coupled metalic structrue between nano-particles and film with micro-nano structures.

  11. ZnO 纳米线与硫掺杂 TiO2微/纳复合材料的制备及其光催化活性%Preparation and Photocatalytic Activity of Micro/Nano-Structured ZnO/S-Doped TiO2 Composites

    Institute of Scientific and Technical Information of China (English)

    张延霖; 谢楚如; 蔡文娟; 吴宏海

    2016-01-01

    采用水热法制备了ZnO纳米线与硫掺杂TiO2( ZnO/S-TiO2)微/纳复合光催化剂,采用SEM、XRD和XPS等方法对复合光催化剂进行表征,探讨了硫掺杂量和煅烧温度对该复合催化剂光催化性能的影响.结果表明,ZnO微米线表面形成了粒径较为均一的纳米S-TiO2颗粒,硫掺杂TiO2中形成了Ti—O—S键;当硫掺杂量为0.8%(物质的量分数)并经500℃高温煅烧的复合光催化剂对菲的降解呈现出最好的光催化活性.%A micro/nano-structured ZnO/S-doped TiO2 composite ( ZnO/S-TiO2 ) was successfully prepared by hy-drothermal method.The structure and morphology of the ZnO/S-TiO2 composite were characterized by SEM, XRD and XPS.The effect of dosage of sulfur doping into titanium dioxide and calcination temperature on photocatalytic activity of ZnO/S-TiO2 composite was discussed.The result indicated that Ti—O—S bond existed and homogeneous S doped TiO2 nanoparticles could be formed on the surface of ZnO.Under the conditions of 0.8%( molar ratio) of sulfur doping and the calcination temperature of 500℃, the synthesized photocatalyst exhibited the best photocata-lytic activity for degradation of phenanthrene.

  12. Alligator osteoderms: Mechanical behavior and hierarchical structure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Irene H. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Yang, Wen, E-mail: wey005@eng.ucsd.edu [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, Marc A. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Departments of Mechanical and Aerospace Engineering and Nanoengineering, University of California, San Diego, La Jolla, CA 92093 (United States)

    2014-02-01

    Osteoderms are bony scutes embedded underneath the dermal layers of the skin acting as a protection of the alligator (Archosauria: Crocodylia) internal organs and tissues. Additionally, these scutes function as an aid in temperature regulation. The scutes are inter-linked by fibrous connective tissue. They have properties similar to bone and thus have the necessary toughness to provide protection against predators. The scutes consist of hydroxyapatite and have a porosity of approximately 12%. They have a disc-like morphology with a ridge along the middle of the plate, called the keel; the outer perimeter of the disc has depressions, grooves, and jagged edges which anchor the collagen and act as sutures. Computerized tomography reveals the pattern of elongated pores, which emanate from the keel in a radial pattern. Micro-indentation measurements along the cross-section show a zigzag behavior due to the porosity. Compression results indicate that the axial direction is the strongest (UTS ∼ 67 MPa) and toughest (11 MJ/m{sup 3}); this is the orientation in which they undergo the largest external compression forces from predator teeth. Toughening mechanisms are identified through observation of the damage progression and interpreted in mechanistic terms. They are: flattening of pores, microcrack opening, and microcrack growth and coalescence. Collagen plays an essential role in toughening and plasticity by providing bridges that impede the opening of the cracks and prevent their growth. - Highlights: • We characterized the hierarchical structure of alligator scute. • The anisotropic mechanical behavior of alligator scute was studied. • Toughening mechanisms were identified at the micro- and nano-levels.

  13. Research on Nanofabrication Technology of Micro-/Nano-Stereo Rapid Prototyping of PCVD

    Institute of Scientific and Technical Information of China (English)

    Sandy; TO

    2002-01-01

    At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS, energy beam etching and micro/nano-machining, etc. A common problem for t hese processes is the difficulty to fabricate arbitrary form for 3-dimensional micro/nano-parts, devices or mechanisms. To develop advanced MEMS manufacturin g technology, and to achieve fabrication of true 3-dimen...

  14. Hierarchically Structured Monolithic ZSM-5 through Macroporous Silica Gel Zeolitization

    Institute of Scientific and Technical Information of China (English)

    Lei Qian; Zhao Tianbo; Li Fengyan; Zong Baoning; Tong Yangchuan

    2006-01-01

    The hierarchically structured ZSM-5 monolith was prepared through transforming the skeletons of the macroporous silica gel into ZSM-5 by the steam-assisted conversion method. The morphology and monolithic shapes of macroporous silica gel were well preserved. The hierarchically structured ZSM-5 monolith exhibited the hierarchical porosity, with mesopores and macropores existing inside the macroporous silica gel, and micropores formed by the ZSM-5. The products have been characterized properly by using the XRD, SEM and N2 adsorption-desorption methods.

  15. Hierarchical Optimization of Material and Structure

    DEFF Research Database (Denmark)

    Rodrigues, Helder C.; Guedes, Jose M.; Bendsøe, Martin P.

    2002-01-01

    This paper describes a hierarchical computational procedure for optimizing material distribution as well as the local material properties of mechanical elements. The local properties are designed using a topology design approach, leading to single scale microstructures, which may be restricted...... in various ways, based on design and manufacturing criteria. Implementation issues are also discussed and computational results illustrate the nature of the procedure....

  16. Hierarchical structure of moral stages assessed by a sorting task

    OpenAIRE

    Van Boom, J; Brugman, D.; Heijden, P.G.M. van der

    2001-01-01

    Following criticism of Kohlberg’s theory of moral judgment, an empirical re-examination of hierarchical stage structure was desirable. Utilizing Piaget’s concept of reflective abstraction as a basis, the hierarchical stage structure was investigated using a new method. Study participants (553 Dutch university students and 196 Russian high school students) sorted statements in terms of moral sophistication. These statements were typical for the different stages of moral development as defined ...

  17. Development of 3d micro-nano hybrid patterns using anodized aluminum and micro-indentation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hong Gue; Kwon, Jong Tae [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of); Seo, Young Ho [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of)], E-mail: mems@kangwon.ac.kr; Kim, Byeong Hee [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of)

    2008-07-31

    We developed a simple and cost-effective method of fabricating 3D micro-nano hybrid patterns in which micro-indentation is applied on the anodized aluminum substrate. Nano-patterns were formed first on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns with a 150 nm-diameter on an aluminum substrate were fabricated by anodizing and alumina removing process. Then, micro-pyramid patterns with a side-length of 50 {mu}m were formed on the nano-patterns using micro-indentation. To verify 3D micro-nano hybrid patterns, we replicated 3D micro-nano hybrid patterns by a hot-embossing process. 3D micro-nano hybrid patterns may be used in nano-photonic devices and nano-biochips applications.

  18. Road Network Selection Based on Road Hierarchical Structure Control

    Directory of Open Access Journals (Sweden)

    HE Haiwei

    2015-04-01

    Full Text Available A new road network selection method based on hierarchical structure is studied. Firstly, road network is built as strokes which are then classified into hierarchical collections according to the criteria of betweenness centrality value (BC value. Secondly, the hierarchical structure of the strokes is enhanced using structural characteristic identification technique. Thirdly, the importance calculation model was established according to the relationships among the hierarchical structure of the strokes. Finally, the importance values of strokes are got supported with the model's hierarchical calculation, and with which the road network is selected. Tests are done to verify the advantage of this method by comparing it with other common stroke-oriented methods using three kinds of typical road network data. Comparision of the results show that this method had few need to semantic data, and could eliminate the negative influence of edge strokes caused by the criteria of BC value well. So, it is better to maintain the global hierarchical structure of road network, and suitable to meet with the selection of various kinds of road network at the same time.

  19. Novel Micro/Nano Approaches for Glucose Measurement Using pH-Sensitive Hydrogels

    Science.gov (United States)

    2005-06-01

    AD Award Number: W81XWH-04-1-0596 TITLE: Novel Micro / Nano Approaches for Glucose Measurement Using pH-Sensitive Hydrogels PRINCIPAL INVESTIGATOR...May 2005 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Novel Micro / Nano Approaches for Glucose Measurement Using pH- 5b. GRANT NUMBER Sensitive Hydrogels...Initially, the NaCI solution was circulated through the cell using a syringe pump . A schematic diagram of the apparatus used in this study was

  20. 3D Printing of Hierarchical Silk Fibroin Structures.

    Science.gov (United States)

    Sommer, Marianne R; Schaffner, Manuel; Carnelli, Davide; Studart, André R

    2016-12-21

    Like many other natural materials, silk is hierarchically structured from the amino acid level up to the cocoon or spider web macroscopic structures. Despite being used industrially in a number of applications, hierarchically structured silk fibroin objects with a similar degree of architectural control as in natural structures have not been produced yet due to limitations in fabrication processes. In a combined top-down and bottom-up approach, we exploit the freedom in macroscopic design offered by 3D printing and the template-guided assembly of ink building blocks at the meso- and nanolevel to fabricate hierarchical silk porous materials with unprecedented structural control. Pores with tunable sizes in the range 40-350 μm are generated by adding sacrificial organic microparticles as templates to a silk fibroin-based ink. Commercially available wax particles or monodisperse polycaprolactone made by microfluidics can be used as microparticle templates. Since closed pores are generated after template removal, an ultrasonication treatment can optionally be used to achieve open porosity. Such pore templating particles can be further modified with nanoparticles to create a hierarchical template that results in porous structures with a defined nanotopography on the pore walls. The hierarchically porous silk structures obtained with this processing technique can potentially be utilized in various application fields from structural materials to thermal insulation to tissue engineering scaffolds.

  1. Macro-, Micro-, Nano- and Crystal Structures of a Homodinuclear Complex [NH3(CH2)3NH3]2{Na2[(C6H4O2)2](C6H4O2H)2}

    Institute of Scientific and Technical Information of China (English)

    LU,Xiao-Ming; WEI,Chun-Xia; WANG,Zhen; YE,Chao-Hui

    2007-01-01

    A homodinuclear complex (NH3CH2CH2CH2NH3)2{Na2[(C6H4O2)2](C6H4O2H)2} (1) has been synthesized by a solution-based self-assembly route. It crystallized in monoclinic system with space group P21/c. Every sodium ion coordinates in a tetragonal prism fashion with two O atoms of a terminal chelating catecholate ligand and three O atoms from two bridging catecholate ligands. Two neighboring NaO5 tetragonal prisms are edge-shared and centrosymmetric with regard to the inversion center to form a binuclear cluster {Na2[(C6H4O2)2](C6H4OOH)2}4- anion.The complex anions were aligned parallelly by π-π interaction and linked with the protonated 1,3-propylenediamine through hydrogen bonds which were assembled into a multi-lamellar structure with channels. The crystal exhibits rectangular geometry with an interior triangle hollow structure under optical microscopy. And the scanning electron microscopy (SEM) indicates that the wall of the tubes shows multi-lamella morphologies. Further, the transmission electron microscopy (TEM) reveals that the crystal is composed of multi-lamellar nano-tubes with diameters less than 100 nm. The molecular structure of the complex was compared with that of its isomer complex 2.

  2. 仿 Mo rpho 蝶翅微纳结构制备及其光学特性%Fabrication and optical characteristics of biomimetic micro-nano structures on Morpho butterfly wing

    Institute of Scientific and Technical Information of China (English)

    廖广兰; 江婷; 江轩; 史铁林

    2014-01-01

    以Morpho Rhetenor蝴蝶鳞翅为研究对象,采用光学显微镜和电子显微镜对其蝶翅表面结构进行分析,提出一种易于操作、成本低的仿蝶翅微纳结构制备方法。以Morpho Rhetenor鳞片为生物模板,采用磁控溅射技术,借助烧结成型工艺,制备出仿蝶翅结构的Al2 O3和ZnO反结构产物。再采用Rsoft软件对蝶翅结构及蝶翅样本的Al2 O3和ZnO遗态结构进行光学仿真模拟,与实测的蝶翅样本反射谱进行比较。研究表明:仿真结果与所制备出的仿蝶翅微纳结构颜色及用低温原子层沉积工艺、溶胶凝胶等方法得到的结果较为近似,从而印证了该工艺的可行性,也为仿生微纳结构的制备及其应用提供了一条具有参考性的途径。%Optical microscope and electron microscopes w ere employed to study the micro‐nano struc‐tures on the Morpho Rhetenor wing .Then a preparation method by magnetron sputtering on the but‐terfly templates followed with sinter molding process was put forward to produce Al2 O3 and ZnO rep‐licas with easier operation and lower cost .An optical simulation software Rsoft was introduced to ob‐tain the reflection efficiency of the butterfly wing ,Al2 O3 and ZnO replicas structures .Research re‐sults show that the simulation results agree well with the color of replicas and other fabrication meth‐ods such as ALD (low‐temperature atomic layer disposition) and sol‐gel ,which confirms the feasibili‐ty of the method ,and also provides an available approach for the fabrication and application of biomi‐metic micro‐nano structures .

  3. Detect overlapping and hierarchical community structure in networks

    CERN Document Server

    Shen, Huawei; Cai, Kai; Hu, Mao-Bin

    2008-01-01

    Clustering and community structure is crucial for many network systems and the related dynamic processes. It has been shown that communities are usually overlapping and hierarchical. However, previous methods investigate these two properties of community structure separately. This paper propose an algorithm (EAGLE) to detect both the overlapping and hierarchical properties of complex community structure together. This algorithm deals with the set of maximal cliques and adopts an agglomerative framework. The quality function of modularity is extended to evaluate the goodness of a cover. The examples of application to real world networks give excellent results.

  4. Trait anxiety, disgust sensitivity, and the hierarchic structure of fears.

    Science.gov (United States)

    McDonald, Scott D; Hartman, Nathan S; Vrana, Scott R

    2008-08-01

    This paper describes an evaluation of Taylor's (1998) hierarchic model of fears and its relationship to trait anxiety and disgust sensitivity (DS). In Study 1 (N=420), a confirmatory factor analysis supported a hierarchic structure of fears. Next, an analysis using structural equation modeling indicated that trait anxiety is associated with claustrophobic and social fears, whereas DS is associated with all four fear subtypes examined (claustrophobic, social, blood-injection-injury and animal). However, trait anxiety and DS did not account for all variance shared by fear subtypes. The addition of a generalized "fear factor" accounted for significant residual shared variance between the four fear subtypes, beyond that accounted for by trait anxiety and DS. Study 2 (N=213) generally replicated these results. Findings suggest that the hierarchic structural model of fears would benefit from inclusion of trait anxiety and DS as higher-order contributors to fearfulness.

  5. Facile solid-state synthesis of Ni@C nanosheet-assembled hierarchical network for high-performance lithium storage

    Science.gov (United States)

    Gu, Jinghe; Li, Qiyun; Zeng, Pan; Meng, Yulin; Zhang, Xiukui; Wu, Ping; Zhou, Yiming

    2017-08-01

    Micro/nano-architectured transition-metal@C hybrids possess unique structural and compositional features toward lithium storage, and are thus expected to manifest ideal anodic performances in advanced lithium-ion batteries (LIBs). Herein, we propose a facile and scalable solid-state coordination and subsequent pyrolysis route for the formation of a novel type of micro/nano-architectured transition-metal@C hybrid (i.e., Ni@C nanosheet-assembled hierarchical network, Ni@C network). Moreover, this coordination-pyrolysis route has also been applied for the construction of bare carbon network using zinc salts instead of nickel salts as precursors. When applied as potential anodic materials in LIBs, the Ni@C network exhibits Ni-content-dependent electrochemical performances, and the partially-etched Ni@C network manifests markedly enhanced Li-storage performances in terms of specific capacities, cycle life, and rate capability than the pristine Ni@C network and carbon network. The proposed solid-state coordination and pyrolysis strategy would open up new opportunities for constructing micro/nano-architectured transition-metal@C hybrids as advanced anode materials for LIBs.

  6. Fabrication of Micro/Nano optical Fiber by Electrospinning Direct-writing

    Science.gov (United States)

    Yifang, Liu

    2017-01-01

    Because of the excellent performance, Micro/Nano optical fiber has been more and more widely applied in passive photonic devices, micro-optical sensors, field of atomic manipulation, etc. Currently the main manufacturing mode of Micro/Nano optical fiber is the stretching method which is susceptible to air impact, vulnerable to contaminant and has poor reproducibility. In order to solve these problems, the fabrication of the Micro/Nano optical fiber by electrospinning direct-writing is researched in this article. The experimental platform is set up after the scheme of electrospinning direct-writing is designed. A series of comparative experiments are carried out with changing three experimental variables. The PMMA Micro/Nano optical fiber of controllable diameter is fabricated by regulating the distance between the sprinkler head and collecting plate, flow rate and concentration of PMMA solution. The testing results indicate that the light transmission power loss rate of the PMMA Micro/Nano optical fiberis 0.41dB/mmexcited by a 633-nm-wavelength light. The problem is expected to be solved by further optimization of the experimental process and parameters.

  7. Performance characteristic of a Stirling refrigeration cycle in micro/nano scale

    Science.gov (United States)

    Nie, Wenjie; He, Jizhou; Du, Jianqiang

    2009-02-01

    The aim of the paper is to present the performance characteristics of a Stirling refrigeration cycle in micro/nano scale, in which the working substance of cycle is an ideal Maxwellian gas. Due to the quantum boundary effect on the gas particles confined in the finite domain, the cycle no longer possesses the condition of perfect regeneration. The inherent regenerative losses, the refrigeration heat and coefficient of performance (COP) of the cycle are derived. It is found that, for the micro/nano scaled Stirling refrigeration cycle devices, the refrigeration heat and COP of cycle all depend on the surface area of the system (boundary of cycle) besides the temperature of the heat reservoirs, the volume of system and other parameters, while for the macro scaled refrigeration cycle devices, the refrigeration heat and COP of cycle are independent of the surface area of the system. Variations of the refrigeration heat ratio rR and the COP ratio rε with the temperature ratio τ and volume ratio rV for the different surface area ratio rA are examined, which reveals the influence of the boundary of cycle on the performance of a micro/nano scaled Stirling refrigeration cycle. The results are useful for designing of a micro/nano scaled Stirling cycle device and may conduce to confirming experimentally the quantum boundary effect in the micro/nano scaled devices.

  8. Numerical investigation on thermal properties at Cu-Al interface in micro/nano manufacturing

    Science.gov (United States)

    Zhang, Liqiang; Yang, Ping; Chen, Min; Liao, Ningbo

    2012-02-01

    A hybrid model by integrating TTM (two-temperature model) and MD (molecular dynamics) is proposed to investigate the properties on interface of dissimilar materials under thermal flux conditions. This model can describe the electron phonon coupling and phonon scattering at the interface of different metals easily. By comparing the Cu-Cu interface and Cu-Al interface, the atoms of the Cu-Cu interface at different sides tend to move together; while, the atoms displacements of Cu and Al are opposite along the interface, which may cause stress and voids at the interface. Moreover, the propagation mechanisms of nanocracks and the corresponding change of temperature distribution and thermal flux are investigated. The results show that the interfaces of dissimilar materials are prone to crack initiations, leading to delaminations because of the high temperature. All these are useful for understanding the deformation and failure of the interfaces structures. It implies a potential method for design and analysis of interface structure in micro/nano manufacturing.

  9. Micro/Nano Gas Sensors: A New Strategy Towards In-Situ Wafer-Level Fabrication of High-Performance Gas Sensing Chips

    Science.gov (United States)

    Xu, Lei; Dai, Zhengfei; Duan, Guotao; Guo, Lianfeng; Wang, Yi; Zhou, Hong; Liu, Yanxiang; Cai, Weiping; Wang, Yuelin; Li, Tie

    2015-01-01

    Nano-structured gas sensing materials, in particular nanoparticles, nanotubes, and nanowires, enable high sensitivity at a ppb level for gas sensors. For practical applications, it is highly desirable to be able to manufacture such gas sensors in batch and at low cost. We present here a strategy of in-situ wafer-level fabrication of the high-performance micro/nano gas sensing chips by naturally integrating microhotplatform (MHP) with nanopore array (NPA). By introducing colloidal crystal template, a wafer-level ordered homogenous SnO2 NPA is synthesized in-situ on a 4-inch MHP wafer, able to produce thousands of gas sensing units in one batch. The integration of micromachining process and nanofabrication process endues micro/nano gas sensing chips at low cost, high throughput, and with high sensitivity (down to ~20 ppb), fast response time (down to ~1 s), and low power consumption (down to ~30 mW). The proposed strategy of integrating MHP with NPA represents a versatile approach for in-situ wafer-level fabrication of high-performance micro/nano gas sensors for real industrial applications. PMID:26001035

  10. Micro-nanofibers with hierarchical structure by bubbfil-spinning

    Directory of Open Access Journals (Sweden)

    Liu Peng

    2015-01-01

    Full Text Available Bubbfil spinning is used to fabricate micro/nanofibers with hierarchical structure. The wall of a polymer film is attenuated unevenly by a blowing air. The burst of the bubble results in film fragments with different thickness, as a result, different sizes of fibers are obtained.

  11. Hierarchically structured superoleophobic surfaces with ultralow contact angle hysteresis.

    Science.gov (United States)

    Kota, Arun K; Li, Yongxin; Mabry, Joseph M; Tuteja, Anish

    2012-11-14

    Hierarchically structured, superoleophobic surfaces are demonstrated that display one of the lowest contact angle hysteresis values ever reported - even with extremely low-surface-tension liquids such as n-heptane. Consequently, these surfaces allow, for the first time, even ≈2 μL n-heptane droplets to bounce and roll-off at tilt angles. ≤ 2°.

  12. Content Consumption and Hierarchical Structures of Web-Supported Courses

    Science.gov (United States)

    Hershkovitz, Arnon; Hardof-Jaffe, Sharon; Nachmias, Rafi

    2014-01-01

    This study presents an empirical investigation of the relationship between the hierarchical structure of content delivered to students within a Learning Management System (LMS) and its actual consumption. To this end, campus-wide data relating to 1,203 courses were collected from the LMS' servers and were subsequently analyzed using data mining…

  13. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Science.gov (United States)

    Saito, Noriko; Haneda, Hajime

    2011-12-01

    We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.

  14. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Directory of Open Access Journals (Sweden)

    Noriko Saito and Hajime Haneda

    2011-01-01

    Full Text Available We review the solvothermal synthesis, using a mixture of ethylene glycol (EG and water as the solvent, of zinc oxide (ZnO particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i EG restricts the growth of ZnO microcrystals, (ii EG promotes the self-assembly of small crystallites into spheroidal particles and (iii the high water content of EG results in hollow spheres.

  15. Evaluating Hierarchical Structure in Music Annotations

    OpenAIRE

    Brian McFee; Oriol Nieto; Morwaread M. Farbood; Juan Pablo Bello

    2017-01-01

    Music exhibits structure at multiple scales, ranging from motifs to large-scale functional components. When inferring the structure of a piece, different listeners may attend to different temporal scales, which can result in disagreements when they describe the same piece. In the field of music informatics research (MIR), it is common to use corpora annotated with structural boundaries at different levels. By quantifying disagreements between multiple annotators, previous research has yielded...

  16. Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

    Science.gov (United States)

    Maryam, Maryam; Dedy, Rahmad; Yunizurwan, Yunizurwan

    2017-01-01

    Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics.

  17. Auction-based resource allocation game under a hierarchical structure

    Science.gov (United States)

    Cui, Yingying; Zou, Suli; Ma, Zhongjing

    2016-01-01

    This paper studies a class of auction-based resource allocation games under a hierarchical structure, such that each supplier is assigned a certain amount of resource from a single provider and allocates it to its buyers with auction mechanisms. To implement the efficient allocations for the underlying hierarchical system, we first design an auction mechanism, for each local system composed of a supplier and its buyers, which inherits the advantages of the progressive second price mechanism. By employing a dynamic algorithm, each local system converges to its own efficient Nash equilibrium, at which the efficient resource allocation is achieved and the bidding prices of all the buyers in this local system are identical with each other. After the local systems reach their own equilibria respectively, the resources assigned to suppliers are readjusted via a dynamic hierarchical algorithm with respect to the bidding prices associated with the implemented equilibria of local systems. By applying the proposed hierarchical process, the formulated hierarchical system can converge to the efficient allocation under certain mild conditions. The developed results in this work are demonstrated with simulations.

  18. Synthesis, characterization, and CO2 capture study of micro-nano carbonaceous composites.

    Science.gov (United States)

    Kong, Yuxia; Jin, Lei; Qiu, Jun

    2013-10-01

    The micro-nano carbonaceous composite activated carbon fiber/carbon nanotube (ACF/CNTs) was obtained by chemical vapor deposition technology with CNTs growth on the substrate ACF, and the composite was further modified by branched polyethyleneimine (PEI). The morphological features of the as-grown ACF/CNTs and PEI-modified samples were analyzed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal gravimetric analysis respectively. Physical properties of the samples were recorded by conducting N2 adsorption/desorption at 77K. CO2 capture tests indicated that both the presence of CNTs and PEI increased the CO2 adsorption capacity, due to the unique hollow tubular structure of CNTs and poly amino groups of PEI. The CO2 adsorption capacities of ACF/CNTs and ACF/CNTs-PEI were tested to be 66.2 mg/g and 98.8 mg/g, respectively at 30°C, which were much higher than that of unmodified ACF (42.4 mg/g). Increasing adsorption temperature up to 60°C further promoted the CO2 adsorption capacity of ACF/CNTs-PEI (121.2 mg/g) due to the maximum equilibrium adsorption between the chemical and physical adsorption at this temperature. Cyclic CO2 adsorption tests via thermal desorption proved that ACF/CNTs-PEI had a good regenerability of 96.2%, suggesting this material is a promising CO2 adsorbent for practical applications.

  19. Directed assembly of colloidal particles for micro/nano photonics (Conference Presentation)

    Science.gov (United States)

    Zheng, Yuebing

    2017-02-01

    Bottom-up fabrication of complex structures with chemically synthesized colloidal particles as building blocks pave an efficient and cost-effective way towards micro/nano photonics with unprecedented functionality and tunability. Novel properties can arise from quantum effects of colloidal particles, as well as inter-particle interactions and spatial arrangement in particle assemblies. Herein, I discuss our recent developments and applications of three types of techniques for directed assembly of colloidal particles: moiré nanosphere lithography (MNSL), bubble-pen lithography (BPL), and optothermal tweezers (OTTs). Specifically, MNSL provides an efficient approach towards creating moiré metasurface with tunable and multiband optical responses from visible to mid-infrared regime. Au moiré metasurfaces have been applied for surface-enhanced infrared spectroscopy, optical capture and patterning of bacteria, and photothermal denaturation of proteins. BPL is developed to pattern a variety of colloidal particles on plasmonic substrates and two-dimensional atomic-layer materials in an arbitrary manner. The laser-directed microbubble captures and immobilizes nanoparticles through coordinated actions of Marangoni convection, surface tension, gas pressure, and substrate adhesion. OTTs are developed to create dynamic nanoparticle assemblies at low optical power. Such nanoparticle assemblies have been used for surface-enhanced Raman spectroscopy for molecular analysis in their native environments.

  20. Observation of the induced pressure in a hybrid micro/nano-channel

    Institute of Scientific and Technical Information of China (English)

    KONG Gao-pan; ZHENG Xu; SILBER-LI Zhan-hua; XU Zheng

    2013-01-01

    This paper studies the flow characteristics in micro/nano-channels subjected to an applied electric field.The nano-channel flow was observed by means of the fluorescence Calcein.A Fluorescence Concentration Gradient Interface (FCGI) was observed across the nano-channel array.The front of the FCGI was shown to have an analogous parabolic shape.The propagation of this interface reflects indirectly the induced pressure at the micro/nano-channel junction,where the enrichment-depletion processes are known to take place.This induced pressure was predicted by numerical simulations,and this paper gives the first experimental evidence.

  1. Zeólitas hierarquicamente estruturadas Hierarchically structured zeolites

    Directory of Open Access Journals (Sweden)

    Saulo de Tarso Figueiredo Grecco

    2013-01-01

    Full Text Available This review presents the main characteristics and properties of microporous (zeolites and ordered mesoporous materials, focusing on structural aspects and preparation. In addition, their use as heterogeneous catalysts are also discussed, with emphasis on their advantages and disadvantages. Due to difficulty in application of zeolites in the conversion of bulky molecules, the most relevant strategies of synthesis for the preparation of zeolitic materials with hierarchical pore structure was also analyzed, which allow this limitation to be overcome.

  2. Sensing nanometric displacement of a micro-/nano-fiber induced by optical forces by use of white light interferometry

    Science.gov (United States)

    Qiu, Weiqia; Huang, Hankai; Yu, Jianhui; Dong, Huazhuo; Chen, Zhe; Lu, Huihui

    2015-07-01

    Sensing the nanometric displacement of a micro-/nano-fiber induced by optical forces is a key technology to study optical forces and optical momentum. When the gap between a micro-/nano-fiber and glass substrate becomes down to micrometer scale or less, a white light interference was observed. The gap changes when optical force arising from the propagating pump light along the micro-/nano-fiber causes a transversal nanometric displacement of a micro-/nanofiber, resulting in movement of the interferometric fringes. Therefore this movement of the interferometric fringes can be used to sense the nanometric displacement of the micro-/nano-fiber induced by optical forces. Experimental results show that the resolutions of this method can reach 7.27nm/pixel for tilted angle 0.8o between the micro-/nano-fiber and substrate. It is concluded that the white light interferometry method is suitable for measuring the weak optical force.

  3. Hierarchical semantic structures for medical NLP.

    Science.gov (United States)

    Taira, Ricky K; Arnold, Corey W

    2013-01-01

    We present a framework for building a medical natural language processing (NLP) system capable of deep understanding of clinical text reports. The framework helps developers understand how various NLP-related efforts and knowledge sources can be integrated. The aspects considered include: 1) computational issues dealing with defining layers of intermediate semantic structures to reduce the dimensionality of the NLP problem; 2) algorithmic issues in which we survey the NLP literature and discuss state-of-the-art procedures used to map between various levels of the hierarchy; and 3) implementation issues to software developers with available resources. The objective of this poster is to educate readers to the various levels of semantic representation (e.g., word level concepts, ontological concepts, logical relations, logical frames, discourse structures, etc.). The poster presents an architecture for which diverse efforts and resources in medical NLP can be integrated in a principled way.

  4. Information and hierarchical structure in financial markets

    Science.gov (United States)

    Mantegna, R. N.

    1999-09-01

    I investigate the information content present in the time series of stock prices of a portfolio of stocks traded in a financial market. By investigating the correlation coefficient between pairs of stocks I provide a working definition of a generalized distance between the stocks of the portfolio. This generalized distance is used to obtain an ultrametric distance matrix between the stocks. The ultrametric structure of the portfolio investigated has associated a taxonomy which is meaningful from an economic point of view.

  5. The Hierarchical Structure and Dynamics of Voids

    CERN Document Server

    Aragon-Calvo, M A

    2012-01-01

    Contrary to the common view voids have very complex internal structure and dynamics. Here we show how the hierarchy of structures in the density field inside voids is reflected by a similar hierarchy of structures in the velocity field. Voids defined by dense filaments and clusters can de described as simple expanding domains with coherent flows everywhere except at their boundaries. At scales smaller that the void radius the velocity field breaks into expanding sub-domains corresponding to sub- voids. These sub-domains break into even smaller sub-sub domains at smaller scales resulting in a nesting hierarchy of locally expanding domains. The ratio between the magnitude of the velocity field responsible for the expansion of the void and the velocity field defining the sub voids is approximately one order of magnitude. The small-scale components of the velocity field play a minor role in the shaping of the voids but they define the local dynamics directly affecting the processes of galaxy formation and evoluti...

  6. Growth Mechanism of Pumpkin-Shaped Vaterite Hierarchical Structures

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2015-03-01

    CaCO3-based biominerals possess sophisticated hierarchical structures and promising mechanical properties. Recent researches imply that vaterite may play an important role in formation of CaCO3-based biominerals. However, as a less common polymorph of CaCO3, the growth mechanism of vaterite remains not very clear. Here we report the growth of a pumpkin-shaped vaterite hierarchical structure with a six-fold symmetrical axis and lamellar microstructure. We demonstrate that the growth is controlled by supersaturation and the intrinsic crystallographic anisotropy of vaterite. For the scenario of high supersaturation, the nucleation rate is higher than the lateral extension rate, favoring the ``double-leaf'' spherulitic growth. Meanwhile, nucleation occurs preferentially in as determined by the crystalline structure of vaterite, modulating the grown products with a hexagonal symmetry. The results are beneficial for an in-depth understanding of the biomineralization of CaCO3. The growth mechanism may also be applicable to interpret the formation of similar hierarchical structures of other materials. The authors gratefully acknowledge the financial support from National Science Foundation of China (Grant Nos. 51172104 and 50972057) and National Key Basic Research Program of China (Grant No. 2010CB630705).

  7. Mg掺杂ZnO微纳米棒与球的制备及生长机制%Preparation and Growth Mechanism of Mg-Doped ZnO Micro-Nano Spheres

    Institute of Scientific and Technical Information of China (English)

    郭建; 谭绪卫; 丁书龙; 徐桥; 彭江强

    2011-01-01

    采用化学气相沉积法(CVD)在导电玻璃衬底上制备了Mg掺杂的ZnO微纳米棒、微纳米球,实验过程不需要催化剂.X射线衍射仪(XRD)分析结果表明制备的Mg掺杂ZnO微纳米棒仍具有六方铅锌矿结构.利用扫描电子显锻镜(SEM)观测,750℃恒温、载入氩气流速为100 mL/min的样品,有微纳米棒、微纳米球的生成.能谱图(EOS)和光致发光谱测试表明微纳米棒中有Mg的掺人.%Mg-doped ZnO micro-nano-rods and micro-nanoparticeles are prepared by chemical vapor deposition ( CVD) without any catalyst. The experimental substrate is conductive glass. X-ray diffraction ( XRD) reveals that the Mg-doped ZnO micro-nano spheres are crystallinity with wurtzite structure . Scanning electron microscopy ( SEM) images show that Micro-nano-rods and micro-nano sphere are synthesized at temperature of 750 ℃ and flow rate of Argon is lOOmL/min. Energy spectra ( EDS) and photoluminescence spectra show that Mg atomics are doped.

  8. Simulating Self-organization and Interference between Certain Hierarchical Structures.

    Science.gov (United States)

    Raczynski, Stanislaw

    2014-10-01

    A model of the dynamics and interactions between organizations with self-organizing hierarchical structures is presented for discrete events. The active objects of the model are individuals (people, organization members). The parameters of an individual are ability, corruption level, resources, and lust for power, among others. Three organizations are generated and interact with each other, attempting to gain more members and power. The individuals appear and disappear, due to a simple 'birth-and-death' process. If an individual disappears from the model, a corresponding reconfiguration in the hierarchical structure occurs. The organization's growth and macro-patterns are the result of the activities of the individuals. The aim of the simulation is to visualize the evolution of the organizations and the stability of the whole system. A 'steady state' for the model is rare; instead, in most parameter configurations, the model enters into oscillations.

  9. Hierarchical Cellular Structures in High-Capacity Cellular Communication Systems

    CERN Document Server

    Jain, R K; Agrawal, N K

    2011-01-01

    In the prevailing cellular environment, it is important to provide the resources for the fluctuating traffic demand exactly in the place and at the time where and when they are needed. In this paper, we explored the ability of hierarchical cellular structures with inter layer reuse to increase the capacity of mobile communication network by applying total frequency hopping (T-FH) and adaptive frequency allocation (AFA) as a strategy to reuse the macro and micro cell resources without frequency planning in indoor pico cells [11]. The practical aspects for designing macro- micro cellular overlays in the existing big urban areas are also explained [4]. Femto cells are inducted in macro / micro / pico cells hierarchical structure to achieve the required QoS cost effectively.

  10. Hierarchical structure of biological systems: A bioengineering approach

    OpenAIRE

    Alcocer-Cuarón, Carlos; Rivera, Ana L; Castaño, Victor M.

    2013-01-01

    A general theory of biological systems, based on few fundamental propositions, allows a generalization of both Wierner and Berthalanffy approaches to theoretical biology. Here, a biological system is defined as a set of self-organized, differentiated elements that interact pair-wise through various networks and media, isolated from other sets by boundaries. Their relation to other systems can be described as a closed loop in a steady-state, which leads to a hierarchical structure and function...

  11. Concept Vector for Similarity Measurement Based on Hierarchical Domain Structure

    OpenAIRE

    Hong Zhe Liu; Hong Bao; Xu

    2012-01-01

    The concept vector model generalizes standard representations of similarity concept in terms of tree-like structure. In the model, each concept node in the hierarchical tree has ancestor and descendent concept nodes composing its relevancy nodes, thus a concept node is represented as a concept vector according to its relevancy nodes' density and the similarity of the two concepts is obtained by computing cosine similarity between their vectors. In addition, the model is adjusted in terms of l...

  12. Controlling pesticide loss by natural porous micro/nano composites: straw ash-based biochar and biosilica.

    Science.gov (United States)

    Cai, Dongqing; Wang, Longhai; Zhang, Guilong; Zhang, Xin; Wu, Zhengyan

    2013-09-25

    Pesticide sprayed onto plant leaves tends to discharge into the environment through rainwater washing, leaching, and volatilization, resulting in severe pollution to soil, water, and air. Here, to control pesticide loss, we developed a loss-control pesticide (LCP) by adding straw ash-based biochar and biosilica (BCS) to traditional pesticide. BCS possesses a porous micro/nano structure and thus can adsorb a large amount of pesticide molecules to form pesticide-BCS complexes that tend to be retained by the rough surface of plant leaves, displaying a high adhesion performance on the leaves; therefore, the pesticide loss decreases, sufficient pesticide for the plant is supplied, and the pollution risk of the pesticide can be substantially lowered.

  13. 分级微纳结构TiO2空心球的制备及其在DSSC中的应用%Preparation of TiO2 hollow spheres with hierarchical micro/nano architectures and its application in dye sensitized solar cells

    Institute of Scientific and Technical Information of China (English)

    马黎; 赵丽; 王世敏; 董兵海; 许祖勋; 卢红兵; 万丽

    2012-01-01

    The TiO2 hollow spheres with diameter of 200 nm and shell thickness of 20~25 nm were synthesized via a templates method using titanium butoxide as the titanium source and ethanol absolute as solvent. The morphology, crystal phases, porous structures and UV-vis spectra of the product were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM) and N2 adsorption-desorption. The results show that the anatase TiO2 hollow sphere (HS) is consist of TiO2 nanometer particles. TiO2 hollow spheres are used in dye-sensitized solar cell (DSSC) to increase the light scattering. By fabrication of TiO2 P25/HS double-layer film electrode, a higher performance of the DSSC (7SC = 15.79 mA cm-2, VOC = 0.653 V, FF = 0.55, η = 6.66%) is obtained compared with the pure P25 nanocrystalline DSSC (7SC = 13.5 mA cm-2, VOC = 0.653 V, FF = 0.53, η = 4.95%).%以钛酸四丁酯为钛源,无水乙醇为溶剂,通过碳球模板法制备出直径为200 nm、壳厚20-25 nm的TiO2空心球(HS).通过X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和N2吸附脱附等对产物的形貌、晶相组成、孔结构和紫外-可见光谱性质进行了表征,结果显示所制备的锐钛矿相TiO2空心微球是由初级结构纳米级TiO2晶粒构成的.将这种TiO2空心球应用于染料敏化太阳电池(DSSC)领域可以提高光阳极对光的散射.通过制备P25/HS-TiO2双层膜电极,相比单纯的P25纳米晶电极(Jsc=13.5 mA cm-2,Voc=0.653 V,FF=0.53,η=4.95%)可以得到更高的光电转化效率(Jsc=15.79 mA cm-2,Voc=0.653 V,FF=0.55,η=6.66%).

  14. Hierarchical structure of moral stages assessed by a sorting task.

    Science.gov (United States)

    Boom, J; Brugman, D; van der Heijden, P G

    2001-01-01

    Following criticism of Kohlberg's theory of moral judgment, an empirical re-examination of hierarchical stage structure was desirable. Utilizing Piaget's concept of reflective abstraction as a basis, the hierarchical stage structure was investigated using a new method. Study participants (553 Dutch university students and 196 Russian high school students) sorted statements in terms of moral sophistication. These statements were typical for the different stages of moral development as defined in Colby and Kohlberg. The rank ordering performed by participants confirmed the hypotheses. First, despite large individual variation, the ordering of the statements that gave the best fit revealed that each consecutive Kohlbergian stage was perceived to be more morally sophisticated. Second, the lower the stage as represented by the items, the higher the agreement among the participants in their ranking; and the higher the stage as represented by the items, the lower the agreement among the participants in the rankings. Moreover, the pivotal point depended on the developmental characteristics of the sample, which demonstrated a developmental effect: The ordering of statements representative of moral stages below one's own current stage was straightforward, whereas the ordering of statements above one's own stage was difficult. It was concluded that the Piagetian idea of reflective abstraction can be used successfully to operationalize and measure the hierarchical nature of moral development.

  15. Hierarchical structuring of liquid crystal polymer-Laponite hybrid materials.

    Science.gov (United States)

    Tritschler, Ulrich; Zlotnikov, Igor; Zaslansky, Paul; Aichmayer, Barbara; Fratzl, Peter; Schlaad, Helmut; Cölfen, Helmut

    2013-09-03

    Biomimetic organic-inorganic composite materials were fabricated via one-step self-organization on three hierarchical levels. The organic component was a polyoxazoline with pendent cholesteryl and carboxyl (N-Boc-protected amino acid) side chains that was able to form a chiral nematic lyotropic phase and bind to positively charged inorganic faces of Laponite. The Laponite particles formed a mesocrystalline arrangement within the liquid-crystal (LC) polymer phase upon shearing a viscous dispersion of Laponite nanoparticles and LC polymer in DMF. Complementary analytical and mechanical characterization techniques (AUC, POM, TEM, SEM, SAXS, μCT, and nanoindentation) covering the millimeter, micrometer, and nanometer length scales reveal the hierarchical structures and properties of the composite materials consisting of different ratios of Laponite nanoparticles and liquid-crystalline polymer.

  16. Study on Hierarchical Structure of Detailed Control Planning

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Using case studies,this paper analyzes the characteristics of detailed control planning and its hierarchical controls,the form and composition of plan content,and methodological innovations.It then suggests improvements to the planning structure that are oriented at adaptability,fairness,centrality,and scientific principles with regard to the content,methods,and results of the planning.Regarding the hierarchical control system,the paper suggests that the detailed control plan should be composed of "block planning" and "plot planning".It is believed that through a combination of block and plot planning,the problem of joining long-term and short-term planning will be solved and it will be possible to address the need for adjustment and revision of detailed control plan.

  17. An interference cancellation strategy for broadcast in hierarchical cell structure

    KAUST Repository

    Yang, Yuli

    2014-12-01

    In this paper, a hierarchical cell structure is considered, where public safety broadcasting is fulfilled in a femtocell located within a macrocell. In the femtocell, also known as local cell, an access point broadcasts to each local node (LN) over an orthogonal frequency sub-band independently. Since the local cell shares the spectrum licensed to the macrocell, a given LN is interfered by transmissions of the macrocell user (MU) in the same sub-band. To improve the broadcast performance in the local cell, a novel scheme is proposed to mitigate the interference from the MU to the LN while achieving diversity gain. For the sake of performance evaluation, ergodic capacity of the proposed scheme is quantified and a corresponding closed-form expression is obtained. By comparing with the traditional scheme that suffers from the MU\\'s interference, numerical results substantiate the advantage of the proposed scheme and provide a useful tool for the broadcast design in hierarchical cell systems.

  18. Nanodomain structures with hierarchical inhomogeneities in PMN-PT.

    Science.gov (United States)

    Kurushima, Kosuke; Kobayashi, Keisuke; Mori, Shigeo

    2012-09-01

    The nanometric domain configuration of (1 - x) Pb(Mg(1/3)Nb(2/3))O(3-x)PbTiO(3) [(1 - x)PMN-xPT] single crystals in the monoclinic phase around a morphotropic phase boundary (MPB) has been examined thoroughly by means of transmission electron microscopy (TEM). Domain structures with hierarchically inhomogeneous configuration were found in the monoclinic phase near the MPB region around x ~ 0.32, which are characterized as nanoscaled lamella-type domain structures with ~10 nm width inside macroscopic-sized banded domains with 100 to 200 nm width. To elucidate formation processes of the domain structures with hierarchically inhomogeneous configuration, an in situ TEM observation of changes of the domain structures in the temperature window between 298K and 500K was carried out. It is revealed that these nanoscaled lamella-type domain structures with ~10 nm width appear inside the banded domains as a result of the tetragonal structure and are inherent to the monoclinic phase.

  19. Gene function prediction based on the Gene Ontology hierarchical structure.

    Science.gov (United States)

    Cheng, Liangxi; Lin, Hongfei; Hu, Yuncui; Wang, Jian; Yang, Zhihao

    2014-01-01

    The information of the Gene Ontology annotation is helpful in the explanation of life science phenomena, and can provide great support for the research of the biomedical field. The use of the Gene Ontology is gradually affecting the way people store and understand bioinformatic data. To facilitate the prediction of gene functions with the aid of text mining methods and existing resources, we transform it into a multi-label top-down classification problem and develop a method that uses the hierarchical relationships in the Gene Ontology structure to relieve the quantitative imbalance of positive and negative training samples. Meanwhile the method enhances the discriminating ability of classifiers by retaining and highlighting the key training samples. Additionally, the top-down classifier based on a tree structure takes the relationship of target classes into consideration and thus solves the incompatibility between the classification results and the Gene Ontology structure. Our experiment on the Gene Ontology annotation corpus achieves an F-value performance of 50.7% (precision: 52.7% recall: 48.9%). The experimental results demonstrate that when the size of training set is small, it can be expanded via topological propagation of associated documents between the parent and child nodes in the tree structure. The top-down classification model applies to the set of texts in an ontology structure or with a hierarchical relationship.

  20. A stochastic model for detecting overlapping and hierarchical community structure.

    Directory of Open Access Journals (Sweden)

    Xiaochun Cao

    Full Text Available Community detection is a fundamental problem in the analysis of complex networks. Recently, many researchers have concentrated on the detection of overlapping communities, where a vertex may belong to more than one community. However, most current methods require the number (or the size of the communities as a priori information, which is usually unavailable in real-world networks. Thus, a practical algorithm should not only find the overlapping community structure, but also automatically determine the number of communities. Furthermore, it is preferable if this method is able to reveal the hierarchical structure of networks as well. In this work, we firstly propose a generative model that employs a nonnegative matrix factorization (NMF formulization with a l(2,1 norm regularization term, balanced by a resolution parameter. The NMF has the nature that provides overlapping community structure by assigning soft membership variables to each vertex; the l(2,1 regularization term is a technique of group sparsity which can automatically determine the number of communities by penalizing too many nonempty communities; and hence the resolution parameter enables us to explore the hierarchical structure of networks. Thereafter, we derive the multiplicative update rule to learn the model parameters, and offer the proof of its correctness. Finally, we test our approach on a variety of synthetic and real-world networks, and compare it with some state-of-the-art algorithms. The results validate the superior performance of our new method.

  1. Hierarchical structure of the otolith of adult wild carp

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhuo; Gao Yonghua [State key laboratory of new ceramics and fine processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State key laboratory of new ceramics and fine processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2009-04-30

    The otolith of adult wild carp contains a pair of asterisci, a pair of lappilli and a pair of sagittae. Current research works are mainly restricted to the field of the daily ring structure. The purpose of this work is to explore the structural characteristics of carp's otolith in terms of hierarchy from nanometer to millimeter scale by transmission election microscope (TEM) and scanning electron microscope (SEM). Based on the observation, carp's lapillus is composed of ordered aragonite crystals. Seven hierarchical levels of the microstructure were proposed and described with the scheme representing a complete organization in detail. SEM studies show not only the clear daily growth increment, but also the morphology within the single daily increment. The domain structure of crystal orientation in otolith was observed for the first time. Furthermore, TEM investigation displays that the lapillus is composed of aragonite crystals with nanometer scale. Four hierarchical levels of the microstructure of the sagitta are also proposed. The asteriscus which is composed of nanometer scale vaterite crystals is considered to have a uniform structure.

  2. Hierarchical optimisation on scissor seat suspension characteristic and structure

    Science.gov (United States)

    Wang, Chunlei; Zhang, Xinjie; Guo, Konghui; Lv, Jiming; Yang, Yi

    2016-11-01

    Scissor seat suspension has been applied widely to attenuate the cab vibrations of commercial vehicles, while its design generally needs a trade-off between the seat acceleration and suspension travel, which creates a typical optimisation issue. A complexity for this issue is that the optimal dynamics parameters are not easy to approach solutions fast and unequivocally. Hence, the hierarchical optimisation on scissor seat suspension characteristic and structure is proposed, providing a top-down methodology with the globally optimal and fast convergent solutions to compromise these design contradictions. In details, a characteristic-oriented non-parametric dynamics model of the scissor seat suspension is formulated firstly via databases, describing its vertical dynamics accurately. Then, the ideal vertical stiffness-damping characteristic is cascaded via the characteristic-oriented model, and the structure parameters are optimised in accordance with a structure-oriented multi-body dynamics model of the scissor seat suspension. Eventually, the seat effective amplitude transmissibility factor, suspension travel and the CPU time for solving are evaluated. The results show the seat suspension performance and convergent speed of the globally optimal solutions are improved well. Hence, the proposed hierarchical optimisation methodology regarding characteristic and structure of the scissor seat suspension is promising for its virtual development.

  3. Connectivity independent protein-structure alignment: a hierarchical approach

    Directory of Open Access Journals (Sweden)

    Schmidt-Goenner Tobias

    2006-11-01

    Full Text Available Abstract Background Protein-structure alignment is a fundamental tool to study protein function, evolution and model building. In the last decade several methods for structure alignment were introduced, but most of them ignore that structurally similar proteins can share the same spatial arrangement of secondary structure elements (SSE but differ in the underlying polypeptide chain connectivity (non-sequential SSE connectivity. Results We perform protein-structure alignment using a two-level hierarchical approach implemented in the program GANGSTA. On the first level, pair contacts and relative orientations between SSEs (i.e. α-helices and β-strands are maximized with a genetic algorithm (GA. On the second level residue pair contacts from the best SSE alignments are optimized. We have tested the method on visually optimized structure alignments of protein pairs (pairwise mode and for database scans. For a given protein structure, our method is able to detect significant structural similarity of functionally important folds with non-sequential SSE connectivity. The performance for structure alignments with strictly sequential SSE connectivity is comparable to that of other structure alignment methods. Conclusion As demonstrated for several applications, GANGSTA finds meaningful protein-structure alignments independent of the SSE connectivity. GANGSTA is able to detect structural similarity of protein folds that are assigned to different superfamilies but nevertheless possess similar structures and perform related functions, even if these proteins differ in SSE connectivity.

  4. Numerical analysis on mechanical behaviors of hierarchical cellular structures with negative Poisson’s ratio

    Science.gov (United States)

    Li, Dong; Yin, Jianhua; Dong, Liang; Lakes, Roderic S.

    2017-02-01

    Two-dimensional hierarchical re-entrant honeycomb structures were designed and the mechanical behaviors of the structures were studied using a finite element method. Hierarchical re-entrant structure of order n (n ≥ 1) was constructed by replacing each vertex of a lower order (n - 1) hierarchical re-entrant structure with a smaller re-entrant hexagon with identical strut aspect ratio. The Poisson’s ratio and energy absorption capacity of re-entrant structures of different hierarchical orders were studied under different compression velocities. The results showed that the Poisson’s ratio of the first and second order hierarchical structures can reach -1.36 and -1.33 with appropriate aspect ratio, 13.8% and 12.1% lower than that of the zeroth order hierarchical structure. The energy absorption capacity of the three models increased with an increasing compression velocity; the second order hierarchical structure exhibited the highest rate of increase in energy absorption capacity with an increasing compression velocity. The plateau stresses of the first and second order hierarchical structures were slightly lower than that of the zeroth order hierarchical structure; however the second order hierarchical structure exhibited the highest energy absorption capacity at high compression velocity (60 m s-1).

  5. Analysis of stability of community structure across multiple hierarchical levels

    CERN Document Server

    Li, Hui-Jia

    2015-01-01

    The analysis of stability of community structure is an important problem for scientists from many fields. Here, we propose a new framework to reveal hidden properties of community structure by quantitatively analyzing the dynamics of Potts model. Specifically we model the Potts procedure of community structure detection by a Markov process, which has a clear mathematical explanation. Critical topological information regarding to multivariate spin configuration could also be inferred from the spectral significance of the Markov process. We test our framework on some example networks and find it doesn't have resolute limitation problem at all. Results have shown the model we proposed is able to uncover hierarchical structure in different scales effectively and efficiently.

  6. Effects of a micro/nano rough strontium-loaded surface on osseointegration

    Directory of Open Access Journals (Sweden)

    Li Y

    2015-07-01

    -Sr groups, respectively. These results suggested that the MNT-Sr surface has a synergistic effect of hierarchical micro/nano-topography and strontium for enhanced osseointegration, and it may be a promising option for clinical use. Compared with the MT surface, the NT-Sr surface significantly improved the differentiation of osteoblasts in vitro. In the in vivo animal experiment, the MT surface significantly enhanced the bone-implant contact and maximal pullout force than the NT-Sr surface. Keywords: surface modification, micro/nanorough, implant

  7. Superhydrophobic bionic surfaces with hierarchical microsphere/SWCNT composite arrays.

    Science.gov (United States)

    Li, Yue; Huang, Xing Jiu; Heo, Sung Hwan; Li, Cun Cheng; Choi, Yang Kyu; Cai, Wei Ping; Cho, Sung Oh

    2007-02-13

    Superhydrophobic bionic surfaces with hierarchical micro/nano structures were synthesized by decorating single-walled or multiwalled carbon nanotubes (CNTs) on monolayer polystyrene colloidal crystals using a wet chemical self-assembly technique and subsequent surface treatment with a low surface-energy material of fluoroalkylsilane. The bionic surfaces are based on the regularly ordered colloidal crystals, and thus the surfaces have a uniform superhydrophobic property on the whole surface. Moreover, the wettability of the bionic surface can be well controlled by changing the distribution density of CNTs or the size of polystyrene microspheres. The morphologies of the synthesized bionic surfaces bear much resemblance to natural lotus leaves, and the wettability exhibited remarkable superhydrophobicity with a water contact angle of about 165 degrees and a sliding angle of 5 degrees.

  8. Automated Manipulation of Micro-Nano Objects with SPM by Using L₁ Adaptive Controller

    Directory of Open Access Journals (Sweden)

    Qinmin Yang

    2012-12-01

    Full Text Available In this paper, a novel control methodology for automatically manipulating micro/nano particles by using a Scanning Probe Microscope (SPM is presented. First\tof all, a mathematical model of micro/nanomanipulation, including the interactive forces and dynamics between the tip, particle and substrate along with the roughness effect of the substrate, is described. Then, the L₁ adaptive control design for the manipulation system of micro/nano objects is presented, which consists of a state predictor with fast adaptation, a piece‐wise continuous adaptive law and a low‐pass filtered control design. This control framework can handle nonlinear uncertainties and ensures uniformly bounded tracking performance. The tracking performance bound can be systematically improved by reducing the step size of integration. Rigorous mathematical proof is provided. Simulation results demonstrate the effectiveness of the presented L₁ adaptive control law on the micro/nanomanipulation model.

  9. Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

    OpenAIRE

    Mackinson, B. L.; S. B. Moran; M. W. Lomas; Stewart, G M; R. P. Kelly

    2014-01-01

    The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th–238U disequilibria and, during two cruises, measured by s...

  10. Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

    OpenAIRE

    Mackinson, B. L.; S. B. Moran; M. W. Lomas; Stewart, G M; R. P. Kelly

    2015-01-01

    The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th–238U disequilibria and, during two cruises, measured by a sediment trap at...

  11. Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

    OpenAIRE

    B. L. Mackinson; Moran, S. B.; M. W. Lomas; Stewart, G. M.; Kelly, R.P.

    2014-01-01

    The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th–238U disequilibria and, during two cruises, measured by s...

  12. Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

    OpenAIRE

    B. L. Mackinson; Moran, S. B.; M. W. Lomas; Stewart, G. M.; Kelly, R.P.

    2015-01-01

    The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th–238U disequilibria and, during two cruises, measured by a sediment trap at...

  13. Impact of Groundwater Salinity on Bioremediation Enhanced by Micro-Nano Bubbles

    OpenAIRE

    2013-01-01

    Micro-nano bubbles (MNBs) technology has shown great potential in groundwater bioremediation because of their large specific surface area, negatively charged surface, long stagnation, high oxygen transfer efficiency, etc. Groundwater salinity, which varies from sites due to different geological and environmental conditions, has a strong impact on the bioremediation effect. However, the groundwater salinity effect on MNBs’ behavior has not been reported. In this study, the size distribution, o...

  14. Thermodynamic analysis of the effect of the hierarchical architecture of a superhydrophobic surface on a condensed drop state.

    Science.gov (United States)

    Liu, Tianqing; Sun, Wei; Sun, Xiangyu; Ai, Hongru

    2010-09-21

    Condensed drops usually display a Wenzel state on a superhydrophobic surface (SHS) only with microrough architecture, while Cassie drops easily appear on a surface with micro-nano hierarchical roughness. The mechanism of this is not very clear. It is important to understand how the hierarchical structure affects the states of condensation drops so that a good SHS can be designed to achieve the highly efficient dropwise condensation. In this study, the interface free energy (IFE) of a local condensate, which comes from the growth and combination of numerous initial condensation nuclei, was calculated during its shape changes from the early flat shape to a Wenzel or Cassie state. The final state of a condensed drop was determined by whether the IFE continuously decreased or a minimum value existed. The calculation results indicate that the condensation drops on the surface only with microroughness display a Wenzel state because the IFE curve of a condensed drop first decreases and then increases, existing at a minimum value corresponding to a Wenzel drop. On a surface with proper hierarchical roughness, however, the interface energy curve of a condensed drop will continuously decline until reaching a Cassie state. Therefore, a condensed drop on a hierarchical roughness surface can spontaneously change into a Cassie state. Besides, the states and apparent contact angles of condensed drops on a SHS with different structural parameters published in the literature were calculated and compared with experimental observations. The results show that the calculated condensed drop states are well-coordinated with experimental clarifications. We can conclude that micro-nano hierarchical roughness is the key structural factor for sustaining condensed drops in a Cassie state on a SHS.

  15. Micro/nano-computed tomography technology for quantitative dynamic, multi-scale imaging of morphogenesis.

    Science.gov (United States)

    Gregg, Chelsea L; Recknagel, Andrew K; Butcher, Jonathan T

    2015-01-01

    Tissue morphogenesis and embryonic development are dynamic events challenging to quantify, especially considering the intricate events that happen simultaneously in different locations and time. Micro- and more recently nano-computed tomography (micro/nanoCT) has been used for the past 15 years to characterize large 3D fields of tortuous geometries at high spatial resolution. We and others have advanced micro/nanoCT imaging strategies for quantifying tissue- and organ-level fate changes throughout morphogenesis. Exogenous soft tissue contrast media enables visualization of vascular lumens and tissues via extravasation. Furthermore, the emergence of antigen-specific tissue contrast enables direct quantitative visualization of protein and mRNA expression. Micro-CT X-ray doses appear to be non-embryotoxic, enabling longitudinal imaging studies in live embryos. In this chapter we present established soft tissue contrast protocols for obtaining high-quality micro/nanoCT images and the image processing techniques useful for quantifying anatomical and physiological information from the data sets.

  16. Silicon Carbide Micro/Nano Systems for Demanding and Harsh Environment Applications

    Science.gov (United States)

    Mehregany, Mehran

    2008-03-01

    Micro/nano systems enable the development of smart products and systems by augmenting the computational ability of microelectronics with the perception and control capabilities of sensors and actuators. Micro/nano systems are also known as micro- and nanoelectromechanical systems (MEMS and NEMS), and have been commercialized in a wide range of applications including crash sensing, blood pressure measurement, optical projection, and fluid flow control to name a few. Silicon, in single- and polycrystalline forms, has been the platform semiconductor material underpinning the fabrication of the mechanical and electronic elements of micro/nano systems. However, the materials properties of silicon impose limitations on its use in harsh environment and demanding applications--for example, those involving operation in the presence of high temperatures, corrosive media, high shock loads, erosive flows, and/or high radiation, or involving performance requirements for the mechanical elements that are beyond silicon's capabilities. Silicon carbide (SiC) is an alternative platform semiconductor material that enables such applications because of its wider bandgap and higher melting/sublimation temperature, elastic modulus, fracture toughness, hardness, chemical inertness, and thermal conductivity. This talk will highlight our most recent SiC material, process, and device advances to enable sensing and actuation in applications such as propulsion instrumentation/control, power generation, resource exploration, nuclear reactor instrumentation, deep space exploration, and communications.

  17. In situ thermomechanical testing methods for micro/nano-scale materials.

    Science.gov (United States)

    Kang, Wonmo; Merrill, Marriner; Wheeler, Jeffrey M

    2017-02-23

    The advance of micro/nanotechnology in energy-harvesting, micropower, electronic devices, and transducers for automobile and aerospace applications has led to the need for accurate thermomechanical characterization of micro/nano-scale materials to ensure their reliability and performance. This persistent need has driven various efforts to develop innovative experimental techniques that overcome the critical challenges associated with precise mechanical and thermal control of micro/nano-scale specimens during material characterization. Here we review recent progress in the development of thermomechanical testing methods from miniaturized versions of conventional macroscopic test systems to the current state of the art of in situ uniaxial testing capabilities in electron microscopes utilizing either indentation-based microcompression or integrated microsystems. We discuss the major advantages/disadvantages of these methods with respect to specimen size, range of temperature control, ease of experimentation and resolution of the measurements. We also identify key challenges in each method. Finally, we summarize some of the important discoveries that have been made using in situ thermomechanical testing and the exciting research opportunities still to come in micro/nano-scale materials.

  18. Preparation and Characterization of Branched Micro/nano Se%枝状微纳米硒的制备与表征

    Institute of Scientific and Technical Information of China (English)

    吴永军

    2015-01-01

    以β- 环糊精为模板剂,采用水热法以L- 半胱氨酸盐酸盐还原亚硒酸制备出具有枝状结构的微纳米硒,使用SEM、TEM、XRD对产物进行了表征,探讨了模板剂用量、反应温度、反应时间对硒晶生长的影响. 研究表明,上述因素对产物的形貌有着显著的影响,实验确定的优化反应条件下制得的枝状微纳米硒形貌规则属于三方相t-Se0,但结晶度不高.%Branched micro/nano Se was prepared by the redaction of L-Cys·HCl and H2SeO3 in hydrothermal method, as β-CD was used as soft template. The structures of products were characterized by SEM,TEM and XRD. Some important factors influencing the morphology of products were studied and discussed, including the amounts of soft template,the reaction temperature and the reaction time. The results showed that external causes had a potent effect on the morphology of micro/nano Se. The uniform branched micro/nano Se prepared under the optimal reaction condition was rhombohedral trigonal selenium, but its crystallinity degree was low.

  19. A mechanism for the cortical computation of hierarchical linguistic structure.

    Science.gov (United States)

    Martin, Andrea E; Doumas, Leonidas A A

    2017-03-01

    Biological systems often detect species-specific signals in the environment. In humans, speech and language are species-specific signals of fundamental biological importance. To detect the linguistic signal, human brains must form hierarchical representations from a sequence of perceptual inputs distributed in time. What mechanism underlies this ability? One hypothesis is that the brain repurposed an available neurobiological mechanism when hierarchical linguistic representation became an efficient solution to a computational problem posed to the organism. Under such an account, a single mechanism must have the capacity to perform multiple, functionally related computations, e.g., detect the linguistic signal and perform other cognitive functions, while, ideally, oscillating like the human brain. We show that a computational model of analogy, built for an entirely different purpose-learning relational reasoning-processes sentences, represents their meaning, and, crucially, exhibits oscillatory activation patterns resembling cortical signals elicited by the same stimuli. Such redundancy in the cortical and machine signals is indicative of formal and mechanistic alignment between representational structure building and "cortical" oscillations. By inductive inference, this synergy suggests that the cortical signal reflects structure generation, just as the machine signal does. A single mechanism-using time to encode information across a layered network-generates the kind of (de)compositional representational hierarchy that is crucial for human language and offers a mechanistic linking hypothesis between linguistic representation and cortical computation.

  20. Colloidal quantum dot solar cells exploiting hierarchical structuring

    KAUST Repository

    Labelle, André J.

    2015-02-11

    Extremely thin-absorber solar cells offer low materials utilization and simplified manufacture but require improved means to enhance photon absorption in the active layer. Here, we report enhanced-absorption colloidal quantum dot (CQD) solar cells that feature transfer-stamped solution-processed pyramid-shaped electrodes employed in a hierarchically structured device. The pyramids increase, by up to a factor of 2, the external quantum efficiency of the device at absorption-limited wavelengths near the absorber band edge. We show that absorption enhancement can be optimized with increased pyramid angle with an appreciable net improvement in power conversion efficiency, that is, with the gain in current associated with improved absorption and extraction overcoming the smaller fractional decrease in open-circuit voltage associated with increased junction area. We show that the hierarchical combination of micron-scale structured electrodes with nanoscale films provides for an optimized enhancement at absorption-limited wavelengths. We fabricate 54.7° pyramid-patterned electrodes, conformally apply the quantum dot films, and report pyramid CQD solar cells that exhibit a 24% improvement in overall short-circuit current density with champion devices providing a power conversion efficiency of 9.2%.

  1. A mechanism for the cortical computation of hierarchical linguistic structure

    Science.gov (United States)

    Doumas, Leonidas A. A.

    2017-01-01

    Biological systems often detect species-specific signals in the environment. In humans, speech and language are species-specific signals of fundamental biological importance. To detect the linguistic signal, human brains must form hierarchical representations from a sequence of perceptual inputs distributed in time. What mechanism underlies this ability? One hypothesis is that the brain repurposed an available neurobiological mechanism when hierarchical linguistic representation became an efficient solution to a computational problem posed to the organism. Under such an account, a single mechanism must have the capacity to perform multiple, functionally related computations, e.g., detect the linguistic signal and perform other cognitive functions, while, ideally, oscillating like the human brain. We show that a computational model of analogy, built for an entirely different purpose—learning relational reasoning—processes sentences, represents their meaning, and, crucially, exhibits oscillatory activation patterns resembling cortical signals elicited by the same stimuli. Such redundancy in the cortical and machine signals is indicative of formal and mechanistic alignment between representational structure building and “cortical” oscillations. By inductive inference, this synergy suggests that the cortical signal reflects structure generation, just as the machine signal does. A single mechanism—using time to encode information across a layered network—generates the kind of (de)compositional representational hierarchy that is crucial for human language and offers a mechanistic linking hypothesis between linguistic representation and cortical computation. PMID:28253256

  2. HD-RNAS: An automated hierarchical database of RNA structures

    Directory of Open Access Journals (Sweden)

    Shubhra Sankar eRay

    2012-04-01

    Full Text Available One of the important goals of most biological investigations is to classify and organize the experimental findings so that they are readily useful for deriving generalized rules. Although there is a huge amount of information on RNA structures in PDB, there are redundant files, ambiguous synthetic sequences etc. Moreover, a systematic hierarchical organization, reflecting RNA classification, is missing in PDB. In this investigation, we have classified all the available RNA crystal structures from PDB through a programmatic approach. Hence, it would be now a simple assignment to regularly update the classification as and when new structures are released. The classification can further determine (i a non-redundant set of RNA structures and (ii if available, a set of structures of identical sequence and function, which can highlight structural polymorphism, ligand-induced conformational alterations etc. Presently, we have classified the available structures (2095 PDB entries having RNA chain longer than 9 nucleotides solved by X-ray crystallography or NMR spectroscopy into nine functional classes. The structures of same function and same source are mostly seen to be similar with subtle differences depending on their functional complexation. The web-server is available online at http://www.saha.ac.in/biop/www/HD-RNAS.html and is updated regularly.

  3. Emergence of hierarchical structural complexities in nanoparticles and their assembly

    Science.gov (United States)

    Zeng, Chenjie; Chen, Yuxiang; Kirschbaum, Kristin; Lambright, Kelly J.; Jin, Rongchao

    2016-12-01

    We demonstrate that nanoparticle self-assembly can reach the same level of hierarchy, complexity, and accuracy as biomolecules. The precise assembly structures of gold nanoparticles (246 gold core atoms with 80 p-methylbenzenethiolate surface ligands) at the atomic, molecular, and nanoscale levels were determined from x-ray diffraction studies. We identified the driving forces and rules that guide the multiscale assembly behavior. The protecting ligands self-organize into rotational and parallel patterns on the nanoparticle surface via C-Hṡṡṡπ interaction, and the symmetry and density of surface patterns dictate directional packing of nanoparticles into crystals with orientational, rotational, and translational orders. Through hierarchical interactions and symmetry matching, the simple building blocks evolve into complex structures, representing an emergent phenomenon in the nanoparticle system.

  4. Genomic analysis of the hierarchical structure of regulatory networks

    Science.gov (United States)

    Yu, Haiyuan; Gerstein, Mark

    2006-01-01

    A fundamental question in biology is how the cell uses transcription factors (TFs) to coordinate the expression of thousands of genes in response to various stimuli. The relationships between TFs and their target genes can be modeled in terms of directed regulatory networks. These relationships, in turn, can be readily compared with commonplace “chain-of-command” structures in social networks, which have characteristic hierarchical layouts. Here, we develop algorithms for identifying generalized hierarchies (allowing for various loop structures) and use these approaches to illuminate extensive pyramid-shaped hierarchical structures existing in the regulatory networks of representative prokaryotes (Escherichia coli) and eukaryotes (Saccharomyces cerevisiae), with most TFs at the bottom levels and only a few master TFs on top. These masters are situated near the center of the protein–protein interaction network, a different type of network from the regulatory one, and they receive most of the input for the whole regulatory hierarchy through protein interactions. Moreover, they have maximal influence over other genes, in terms of affecting expression-level changes. Surprisingly, however, TFs at the bottom of the regulatory hierarchy are more essential to the viability of the cell. Finally, one might think master TFs achieve their wide influence through directly regulating many targets, but TFs with most direct targets are in the middle of the hierarchy. We find, in fact, that these midlevel TFs are “control bottlenecks” in the hierarchy, and this great degree of control for “middle managers” has parallels in efficient social structures in various corporate and governmental settings. PMID:17003135

  5. Hybrid Direct Write Lithographic Strategies for Complex Hierarchical Structures

    Science.gov (United States)

    Singer, Jonathan P.

    With the number of alternative lithographic techniques for high resolution and 3D patterning rapidly increasing, there is a need to identify a set of scalable techniques which balances the ability to arbitrarily control every detail of a target pattern and to produce these complex patterns at a high rate. It is in this way that metamaterial devices put forward on a lab scale for applications such as phononics, photonics, and plasmonics can be realized in the industrial scale. This thesis, in approaching this challenge, utilizes combinations of patterning techniques, leveraging the ability for "large" scale alternative lithographic techniques, such as interference lithography or self-assembly, to create the same nanostructured morphology over a large area combined with laser direct write. The process of drawing a single line or isolated voxel can result in a hierarchical pattern defined by the latent motif of the larger-scale technique. The net resuh is to shift the burden of high resolution patterning from the direct write to the large scale technique, effectively decoupling the correlation between the level of detail and the patterning speed and control. More specifically, the following combinations with laser direct writing were investigated: (1) proximity field nanopatterning for the predefinition of diffraction-order-defined 3D resonators which were applied as "stand-up" plasmodic microresonators, (2) dewetting to conduct development-free 2D patterning of isolated sub-micron lines, and, via overlap effects, nanoscale ( <1 00 nm) gratings, (3) block copolymer self-assembly to initiate the simultaneous annealing and alignment of near-equilibrium microdomains from a metastable starting morphology, and (4) interference lithography to fabricate 3D sub-micron periodic and quasiperiodic hierarchical structures with controllable positioning and tunable fill fraction that has potential for applications to microphotonics. In conjunction with the experimental components

  6. The structure of dark matter halos in hierarchical clustering theories

    CERN Document Server

    Subramanian, K; Ostriker, J P; Subramanian, Kandaswamy; Cen, Renyue; Ostriker, Jeremiah P.

    1999-01-01

    During hierarchical clustering, smaller masses generally collapse earlier than larger masses and so are denser on the average. The core of a small mass halo could be dense enough to resist disruption and survive undigested, when it is incorporated into a bigger object. We explore the possibility that a nested sequence of undigested cores in the center of the halo, which have survived the hierarchical, inhomogeneous collapse to form larger and larger objects, determines the halo structure in the inner regions. For a flat universe with $P(k) \\propto k^n$, scaling arguments then suggest that the core density profile is, $\\rho \\propto r^{-\\alpha}$ with $\\alpha = (9+3n)/(5+n)$. But whether such behaviour obtains depends on detailed dynamics. We first examine the dynamics using a fluid approach to the self-similar collapse solutions for the dark matter phase space density, including the effect of velocity dispersions. We highlight the importance of tangential velocity dispersions to obtain density profiles shallowe...

  7. Mesopore quality determines the lifetime of hierarchically structured zeolite catalysts

    Science.gov (United States)

    Milina, Maria; Mitchell, Sharon; Crivelli, Paolo; Cooke, David; Pérez-Ramírez, Javier

    2014-05-01

    Deactivation due to coking limits the lifetime of zeolite catalysts in the production of chemicals and fuels. Superior performance can be achieved through hierarchically structuring the zeolite porosity, yet no relation has been established between the mesopore architecture and the catalyst lifetime. Here we introduce a top-down demetallation strategy to locate mesopores in different regions of MFI-type crystals with identical bulk porous and acidic properties. In contrast, well-established bottom-up strategies as carbon templating and seed silanization fail to yield materials with matching characteristics. Advanced characterization tools capable of accurately discriminating the mesopore size, distribution and connectivity are applied to corroborate the concept of mesopore quality. Positron annihilation lifetime spectroscopy proves powerful to quantify the global connectivity of the intracrystalline pore network, which, as demonstrated in the conversions of methanol or of propanal to hydrocarbons, is closely linked to the lifetime of zeolite catalysts. The findings emphasize the need to aptly tailor hierarchical materials for maximal catalytic advantage.

  8. Uncovering hierarchical data structure in single molecule transport

    Science.gov (United States)

    Wu, Ben H.; Ivie, Jeffrey A.; Johnson, Tyler K.; Monti, Oliver L. A.

    2017-03-01

    Interpretation of single molecule transport data is complicated by the fact that all such data are inherently highly stochastic in nature. Features are often broad, seemingly unstructured and distributed over more than an order of magnitude. However, the distribution contains information necessary for capturing the full variety of processes relevant in nanoscale transport, and a better understanding of its hierarchical structure is needed to gain deeper insight into the physics and chemistry of single molecule electronics. Here, we describe a novel data analysis approach based on hierarchical clustering to aid in the interpretation of single molecule conductance-displacement histograms. The primary purpose of statistically partitioning transport data is to provide avenues for unbiased hypothesis generation in single molecule break junction experiments by revealing otherwise potentially hidden aspects in the conductance data. Our approach is generalizable to the analysis of a wide variety of other single molecule experiments in molecular electronics, as well as in single molecule fluorescence spectroscopy, force microscopy, and ion-channel conductance measurements.

  9. Nanowire-based polypyrrole hierarchical structures synthesized by a two-step electrochemical method.

    Science.gov (United States)

    Ge, Dongtao; Huang, Sanqing; Qi, Rucai; Mu, Jing; Shen, Yuqing; Shi, Wei

    2009-08-03

    A simple two-step electrochemical method is proposed for the synthesis of nanowire-based polypyrrole hierarchical structures. In the first step, microstructured polypyrrole films are prepared by electropolymerization. Then, polypyrrole nanowires are electrodeposited on the surface of the as-synthesized microstructured polypyrrole films. As a result, hierarchical structures of polypyrrole nanowires on polypyrrole microstructures are obtained. The surface wettabilities of the resulting nanowire-based polypyrrole hierarchical structures are examined. It is expected that this two-step method can be developed into a versatile route to produce nanowire-based polypyrrole hierarchical structures with different morphologies and surface properties.

  10. YAP-mediated mechanotransduction regulates osteogenic and adipogenic differentiation of BMSCs on hierarchical structure.

    Science.gov (United States)

    Pan, Houhua; Xie, Youtao; Zhang, Zequan; Li, Kai; Hu, Dandan; Zheng, Xuebin; Fan, Qiming; Tang, Tingting

    2017-04-01

    Hierarchical structure mimicking the natural bone microenvironment has been considered as a promising platform to regulate cell functions. We have previously fabricated hierarchical macropore/nanowire structure and evidence has shown that it can better manipulate the cytoskeleton status and osteogenic performance of osteoblasts. However, how cues of hierarchical structure are translated and ultimately linked to BMSC lineage commitment have still remained elusive, which hinders the accurate knowledge and further development of the hierarchical structure. In this study, bone marrow-derived mesenchymal stem cells (BMSCs) fate on hierarchical structure was investigated as well as the detailed mechanisms. It was shown that well-developed cytoskeleton and focal adhesion were observed for BMSCs on hierarchical structure, which was accompanied by enhanced osteogenic and depressed adipogenic potential. Evidence of increased YAP activity and nuclear translocation were exhibited on hierarchical structure and YAP knockdown inhibited osteogenic differentiation and promoted adipogenic differentiation induced by hierarchical structure. Further remove of cytoskeleton tension inhibited YAP function, which confirmed the key role of YAP-mediated mechanotransduction in the BMSC differentiation. These results together provide information of the stem cell fate commitment on hierarchical structure and a promising approach to design advanced biomaterials by focusing on specific mechanotransduction process.

  11. Injection molding tools with micro/nano-meter pattern

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to methods for embedded a micrometer and/or nanometer pattern into an injection molding tool. In a first main aspect, a micro/nanometer structured imprinting device is applied in, or on, an active surface so as to transfer the micro/nanometer patterned structure to t...

  12. Hierarchical Structure in Semicrystalline Polymers Tethered to Nanospheres

    KAUST Repository

    Kim, Sung A

    2014-01-28

    We report on structural and dynamic transitions of polymers tethered to nanoparticles. In particular, we use X-ray diffraction, vibrational spectroscopy, and thermal measurements to investigate multiscale structure and dynamic transitions of poly(ethylene glycol) (PEG) chains densely grafted to SiO2 nanoparticles. The approach used for synthesizing these hybrid particles leads to homogeneous SiO2-PEG composites with polymer grafting densities as high as 1.5 chains/nm2, which allows the hybrid materials to exist as self-suspended suspensions with distinct hierarchical structure and thermal properties. On angstrom and nanometer length scales, the tethered PEG chains exhibit more dominant TTG conformations and helix unit cell structure, in comparison to the untethered polymer. The nanoparticle tethered PEG chains are also reported to form extended crystallites on tens of nanometers length scales and to exhibit more stable crystalline structure on small dimensions. On length scales comparable to the size of each hybrid SiO 2-PEG unit, the materials are amorphous presumably as a result of the difficulty fitting the nanoparticle anchors into the PEG crystal lattice. This structural change produces large effects on the thermal transitions of PEG molecules tethered to nanoparticles. © 2014 American Chemical Society.

  13. Hierarchical Sets: Analyzing Pangenome Structure through Scalable Set Visualizations

    DEFF Research Database (Denmark)

    Pedersen, Thomas Lin

    2017-01-01

    The increase in available microbial genome sequences has resulted in an increase in the size of the pangenomes being analyzed. Current pangenome visualizations are not intended for the pangenome sizes possible today and new approaches are necessary in order to convert the increase in available...... information to increase in knowledge. As the pangenome data structure is essentially a collection of sets we explore the potential for scalable set visualization as a tool for pangenome analysis. We present a new hierarchical clustering algorithm based on set arithmetics that optimizes the intersection sizes...... along the branches. The intersection and union sizes along the hierarchy are visualized using a composite dendrogram and icicle plot, which, in pangenome context, shows the evolution of pangenome and core size along the evolutionary hierarchy. Outlying elements, i.e. elements whose presence pattern do...

  14. Injection molding tools with micro/nano-meter pattern

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to methods for embedded a micrometer and/or nanometer pattern into an injection molding tool. In a first main aspect, a micro/nanometer structured imprinting device is applied in, or on, an active surface so as to transfer the micro/nanometer patterned structure...... to the tool while the imprinting device is, at least partly, within a cavity of the injection molding tool. In a second main aspect, a base plate with a micro/nanometer structured pattern positioned on an upper part is positioned on the active surface within the tool, the lower part of the base plate facing...... the tool, the active surface receiving the base plate being non-planar on a macroscopic scale. Both aspects enable a simple and effective way of transferring the pattern, and the pattern may be transferred on the active working site of tool immediately prior to molding without the need for extensive...

  15. Facile template-free synthesis of pine needle-like Pd micro/nano-leaves and their associated electro-catalytic activities toward oxidation of formic acid

    Directory of Open Access Journals (Sweden)

    Wang Chuanyi

    2011-01-01

    Full Text Available Abstract Pine needle-like Pd micro/nano-leaves have been synthesized by a facile, template-free electrochemical method. As-synthesized Pd micro/nano-leaves were directly electrodeposited on an indium tin oxide substrate in the presence of 1.0 mM H2PdCl4 + 0.33 M H3PO4. The formation processes of Pd micro/nano-leaves were revealed by scanning electron microscope, and further characterized by X-ray diffraction and electrochemical analysis. Compared to conventional Pd nanoparticles, as-prepared Pd micro/nano-leaves exhibit superior electrocatalytic activities for the formic acid oxidation.

  16. Facile template-free synthesis of pine needle-like Pd micro/nano-leaves and their associated electro-catalytic activities toward oxidation of formic acid

    Science.gov (United States)

    Zhou, Rong; Zhou, Weiqiang; Zhang, Hongmei; Du, Yukou; Yang, Ping; Wang, Chuanyi; Xu, Jingkun

    2011-05-01

    Pine needle-like Pd micro/nano-leaves have been synthesized by a facile, template-free electrochemical method. As-synthesized Pd micro/nano-leaves were directly electrodeposited on an indium tin oxide substrate in the presence of 1.0 mM H2PdCl4 + 0.33 M H3PO4. The formation processes of Pd micro/nano-leaves were revealed by scanning electron microscope, and further characterized by X-ray diffraction and electrochemical analysis. Compared to conventional Pd nanoparticles, as-prepared Pd micro/nano-leaves exhibit superior electrocatalytic activities for the formic acid oxidation.

  17. Tensegrity I. Cell structure and hierarchical systems biology

    Science.gov (United States)

    Ingber, Donald E.

    2003-01-01

    In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

  18. The fragmentation and stability of hierarchical structure in Serpens South

    CERN Document Server

    Friesen, R K; Di Francesco, J; Gutermuth, R; Myers, P C

    2016-01-01

    Filamentary structures are ubiquitous in molecular clouds, and have been recently argued to play an important role in regulating the size and mass of embedded clumps through fragmentation and mass accretion. Here, we reveal the dynamical state and fragmentation of filamentary molecular gas associated with the Serpens South protocluster through analysis of wide (~4 x 4 pc) observations of NH3 (1,1) and (2,2) inversion transitions with the Green Bank Telescope. Detailed modeling of the NH3 lines reveals that the kinematics of the cluster and surrounding filaments are complex. We identify hierarchical structure using a dendrogram analysis of the NH3 emission. The distance between neighbour structures that are embedded within the same parent structure is generally greater than expected from a spherical Jeans analysis, and is in better agreement with cylindrical fragmentation models. The NH3 line width-size relation is flat, and average gas motions are sub- or trans-sonic over all physical scales observed. Subsoni...

  19. Tensegrity I. Cell structure and hierarchical systems biology

    Science.gov (United States)

    Ingber, Donald E.

    2003-01-01

    In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

  20. Efficient Si photovoltaic devices with integrated micro/nano holes

    Science.gov (United States)

    Cansizoglu, Hilal; Gao, Yang; Kaya, Ahmet; Ghandiparsi, Soroush; Polat, Kazim G.; Wang, Yichuan; Zhang, Runzhou; Reggad, Hind; Mayet, Ahmed; Ponizovskaya Devine, Ekaterina; Islam, M. Saif

    2016-09-01

    Efficient light harvesting in a thin layer of crystalline Si can be realized by implementing nanoscale pillars and holes to the device structure. The major drawback of the pillars and holes based photovoltaic devices is high surface to volume ratio, contributing to an increase in surface recombination rate of the photo-generated carriers. The common techniques used in pillars/holes fabrication such as dry etching make the surface even worse by bombarding it with high energy ions. Therefore, such damaged surfaces of high aspect ratio structures need to be effectively passivated. In this study, we demonstrate a hole based thin crystalline Si photovoltaic device with enhanced open circuit voltage and short circuit current after a successful surface passivation process through a wet oxidation. In addition, the effect of passivation layer fabricated by rapid thermal oxide growth on photo response is investigated. A successful fabrication of thin crystalline Si solar cells can lead to the applications of ultra-thin, highly efficient, flexible and wearable energy sources.

  1. Amino acids assisted hydrothermal synthesis of hierarchically structured ZnO with enhanced photocatalytic activities

    Science.gov (United States)

    Guo, Yanxia; Lin, Siwen; Li, Xuan; Liu, Yuping

    2016-10-01

    Novel hierarchically structured ZnO, including rose-like, dandelion-like and flower-like, have been synthesized through a simple hydrothermal process using different amino acids (glutamine, histidine and glycine) as structure-directing agents and urea as deposition agent, followed by subsequent calcination. Amino acids played a crucial role in the formation of hierarchically structured ZnO, and different amino acids could induce different exquisite shapes and assembly ways, as well as more oxygen defects. The prepared hierarchically structured ZnO exhibited excellent photocatalytic activities for the photodegradation of Rhodamine B, which was associated with their special hierarchical structures, large BET surface area and the existence of more oxygen defects. Amino acid-assisted growth mechanism of hierarchically structured ZnO was also discussed.

  2. Advances in lasers and optical micro-nano-systems

    Science.gov (United States)

    Laurell, F.; Fazio, E.

    2010-09-01

    Lasers represent a well consolidated technology: nevertheless, research in this field remains very active and productive, in both basic and applied directions. At the moment significant attention is given to those sources that bring together high power and compactness. Such high power lasers find important applications for material treatments and such applications are presented by Ehsani et al and Saiedeh Saghafi et al, in the treatment of dielectric thin films (Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams) or of biological tissues like pistachio seeds (Investigating the effects of laser beams (532 and 660 nm) in annihilation of pistachio mould fungus using spectrophotometry analysis). In particular the latter paper show how laser sources can find very important applications in new domains, preserving goods and food without the need for preservatives or pesticides by simply sterilizing them using light. Optical Micro and Nano Systems presents a new domain for exploration. In this framework this special issue is very attractive, because it assembles papers reporting new results in three directions: new techniques for monitoring integrated micro- and nano-systems, new integrated systems and novel high performance metamaterial configurations. Integrated micro-components can be monitored and controlled using reflectance measurements as presented by Piombini et al (Toward the reflectance measurement of micro components). Speckle formation during laser beam reflection can also be a very sophisticated tool for detecting ultra-precise displacements, as presented by Filter et al (High resolution displacement detection with speckles : accuracy limits in linear displacement speckle metrology). Three dimensional integrated optical structures is indeed a big challenge and a peculiarity of photonics, they can be formed through traditional holography or using more sophisticated and novel ! technologies. Thus, special

  3. Interaction of light with hematite hierarchical structures: Experiments and simulations

    Science.gov (United States)

    Distaso, Monica; Zhuromskyy, Oleksander; Seemann, Benjamin; Pflug, Lukas; Mačković, Mirza; Encina, Ezequiel; Taylor, Robin Klupp; Müller, Rolf; Leugering, Günter; Spiecker, Erdmann; Peschel, Ulf; Peukert, Wolfgang

    2017-03-01

    Mesocrystalline particles have been recognized as a class of multifunctional materials with potential applications in different fields. However, the internal organization of nanocomposite mesocrystals and its influence on the final properties have not yet been investigated. In this paper, a novel strategy based on electrodynamic simulations is developed to shed light on how the internal structure of mesocrystals influences their optical properties. In a first instance, a unified design protocol is reported for the fabrication of hematite/PVP particles with different morphologies such as pseudo-cubes, rods-like and apple-like structures and controlled particle size distributions. The optical properties of hematite/PVP mesocrystals are effectively simulated by taking their aggregate and nanocomposite structure into consideration. The superposition T-Matrix approach accounts for the aggregate nature of mesocrystalline particles and validate the effective medium approximation used in the framework of the Mie theory and electromagnetic simulation such as Finite Element Method. The approach described in our paper provides the framework to understand and predict the optical properties of mesocrystals and more general, of hierarchical nanostructured particles.

  4. Hierarchical spatial structure of stream fish colonization and extinction

    Science.gov (United States)

    Hitt, N.P.; Roberts, J.H.

    2012-01-01

    Spatial variation in extinction and colonization is expected to influence community composition over time. In stream fish communities, local species richness (alpha diversity) and species turnover (beta diversity) are thought to be regulated by high extinction rates in headwater streams and high colonization rates in downstream areas. We evaluated the spatiotemporal structure of fish communities in streams originally surveyed by Burton and Odum 1945 (Ecology 26: 182-194) in Virginia, USA and explored the effects of species traits on extinction and colonization dynamics. We documented dramatic changes in fish community structure at both the site and stream scales. Of the 34 fish species observed, 20 (59%) were present in both time periods, but 11 (32%) colonized the study area and three (9%) were extirpated over time. Within streams, alpha diversity increased in two of three streams but beta diversity decreased dramatically in all streams due to fish community homogenization caused by colonization of common species and extirpation of rare species. Among streams, however, fish communities differentiated over time. Regression trees indicated that reproductive life-history traits such as spawning mound construction, associations with mound-building species, and high fecundity were important predictors of species persistence or colonization. Conversely, native fishes not associated with mound-building exhibited the highest rates of extirpation from streams. Our results demonstrate that stream fish colonization and extinction dynamics exhibit hierarchical spatial structure and suggest that mound-building fishes serve as keystone species for colonization of headwater streams.

  5. Decoupled Hierarchical Structures for Suppression of Leidenfrost Phenomenon.

    Science.gov (United States)

    Farokhnia, Nazanin; Sajadi, Seyed Mohammad; Irajizad, Peyman; Ghasemi, Hadi

    2017-03-14

    Thermal management of high temperature systems through cooling droplets is limited by the existence of the Leidenfrost point (LFP), at which the formation of a continuous vapor film between a hot solid and a cooling droplet diminishes the heat transfer rate. This limit results in a bottleneck for the advancement of the wide spectrum of systems including high-temperature power generation, electronics/photonics, reactors, and spacecraft. Despite a long time effort on development of surfaces for suppression of this phenomenon, this limit has only shifted to higher temperatures, but still exists. Here, we report a new multiscale decoupled hierarchical structure that suppress the Leidenfrost state and provide efficient heat dissipation at high temperatures. The architecture of these structures is composed of a nanomembrane assembled on top of a deep micropillar structure. This architecture allows to independently tune the involved forces and to suppress LFP. Once a cooling droplet contacts these surfaces, by rerouting the path of vapor flow, the cooling droplet remains attached to the hot solid substrates even at high temperatures (up to 570 °C) for heat dissipation with no existence of Leidenfrost phenomenon. These new surfaces offer unprecedented heat dissipation capacity at high temperatures (2 orders of magnitude higher than the other state-of-the-art surfaces). We envision that these surfaces open a new avenue in thermal management of high-temperature systems through spray cooling.

  6. Structure of urban movements: polycentric activity and entangled hierarchical flows.

    Directory of Open Access Journals (Sweden)

    Camille Roth

    Full Text Available The spatial arrangement of urban hubs and centers and how individuals interact with these centers is a crucial problem with many applications ranging from urban planning to epidemiology. We utilize here in an unprecedented manner the large scale, real-time 'Oyster' card database of individual person movements in the London subway to reveal the structure and organization of the city. We show that patterns of intraurban movement are strongly heterogeneous in terms of volume, but not in terms of distance travelled, and that there is a polycentric structure composed of large flows organized around a limited number of activity centers. For smaller flows, the pattern of connections becomes richer and more complex and is not strictly hierarchical since it mixes different levels consisting of different orders of magnitude. This new understanding can shed light on the impact of new urban projects on the evolution of the polycentric configuration of a city and the dense structure of its centers and it provides an initial approach to modeling flows in an urban system.

  7. Growth Mechanism of a Unique Hierarchical Vaterite Structure

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2013-03-01

    Calcium carbonate is one of the most significant minerals in nature as well as in biogenic sources. Calcium carbonate occurs naturally in three crystalline polymorphs, i.e., calcite, aragonite, and vaterite. Although it has been attracted much research attention to understanding of the formation mechanisms of the material, the properties of the vaterite polymorph is not well known. Here we report synthesis and formation mechanism of a unique hierarchical structure of vaterite. The material is grown by a controlled diffusion method. The structure possesses a core and an outer part. The core is convex lens-like and is formed by vaterite nanocrystals that have small misorientations. The outer part is separated into six garlic clove-like segments. Each segment possesses piles of plate-like vaterite crystals, and the orientations of the plates continuously change from pile to pile. Based on real-time experimental results and the structural analysis, a growth mechanism is presented. Work supported by NSFC (Grant No. 51172104) and MOST of China (Grant No. 2101CB630705)

  8. Fabricating bio-inspired micro/nano-particles by polydopamine coating and surface interactions with blood platelets

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Wei [Jiangsu Provincial Key Lab for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003 (China); State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Shi, Qiang, E-mail: shiqiang@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Hou, Jianwen; Gao, Jian; Li, Chunming; Jin, Jing; Shi, Hengchong [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yin, Jinghua, E-mail: yinjh@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2015-10-01

    Graphical abstract: The particles or particle aggregations activate the blood platelets and provide the physical adhesive sites for platelets adhesion. - Highlights: • Particles with varied sizes and surface properties were fabricated by facile polydopamine (PDA) coating on polystyrene microsphere. • The direct interaction between PDA particles and blood platelets was qualitatively investigated. • The knowledge on platelet–particle interactions provided the basic principle to select biocompatible micro/nano-particles in biomedical field. - Abstract: Although bio-inspired polydopamine (PDA) micro/nano-particles show great promise for biomedical applications, the knowledge on the interactions between micro/nano-particles and platelets is still lacking. Here, we fabricate PDA-coated micro/nano-particles and investigate the platelet–particle surface interactions. Our strategy takes the advantage of facile PDA coating on polystyrene (PS) microsphere to fabricate particles with varied sizes and surface properties, and the chemical reactivity of PDA layers to immobilize fibrinogen and bovine serum albumin to manipulate platelet activation and adhesion. We demonstrate that PS particles activate the platelets in the size-dependent manner, but PDA nanoparticles have slight effect on platelet activation; PS particles promote platelet adhesion while PDA particles reduce platelet adhesion on the patterned surface; Particles interact with platelets through activating the glycoprotein integrin receptor of platelets and providing physical sites for initial platelet adhesion. Our work sheds new light on the interaction between platelets and particles, which provides the basic principle to select biocompatible micro/nano-particles in biomedical field.

  9. Micro/Nano Multilayered Scaffolds of PLGA and Collagen by Alternately Electrospinning for Bone Tissue Engineering.

    Science.gov (United States)

    Kwak, Sanghwa; Haider, Adnan; Gupta, Kailash Chandra; Kim, Sukyoung; Kang, Inn-Kyu

    2016-12-01

    The dual extrusion electrospinning technique was used to fabricate multilayered 3D scaffolds by stacking microfibrous meshes of poly(lactic acid-co-glycolic acid) (PLGA) in alternate fashion to micro/nano mixed fibrous meshes of PLGA and collagen. To fabricate the multilayered scaffold, 35 wt% solution of PLGA in THF-DMF binary solvent (3:1) and 5 wt% solution of collagen in hexafluoroisopropanol (HFIP) with and without hydroxyapatite nanorods (nHA) were used. The dual and individual electrospinning of PLGA and collagen were carried out at flow rates of 1.0 and 0.5 mL/h, respectively, at an applied voltage of 20 kV. The density of collagen fibers in multilayered scaffolds has controlled the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. The homogeneous dispersion of glutamic acid-modified hydroxyapatite nanorods (nHA-GA) in collagen solution has improved the osteogenic properties of fabricated multilayered scaffolds. The fabricated multilayered scaffolds were characterized using FT-IR, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). The scanning electron microscopy (FE-SEM) was used to evaluate the adhesion and spreads of MC3T3-E1 cells on multilayered scaffolds. The activity of MC3T3-E1 cells on the multilayered scaffolds was evaluated by applying MTT, alkaline phosphatase, Alizarin Red, von Kossa, and cytoskeleton F-actin assaying protocols. The micro/nano fibrous PLGA-Col-HA scaffolds were found to be highly bioactive in comparison to pristine microfibrous PLGA and micro/nano mixed fibrous PLGA and Col scaffolds.

  10. A New XYZ Compliant Parallel Mechanism for Micro-/Nano-Manipulation: Design and Analysis

    Directory of Open Access Journals (Sweden)

    Haiyang Li

    2016-02-01

    Full Text Available Based on the constraint and position identification (CPI approach for synthesizing XYZ compliant parallel mechanisms (CPMs and configuration modifications, this paper proposes a new fully-symmetrical XYZ CPM with desired motion characteristics such as reduced cross-axis coupling, minimized lost motion, and relatively small parasitic motion. The good motion characteristics arise from not only its symmetric configuration, but also the rigid linkages between non-adjacent rigid stages. Comprehensive kinematic analysis is carried out based on a series of finite element simulations over a motion range per axis less than ±5% of the beam length, which reveals that the maximum cross-axis coupling rate is less than 0.86%, the maximum lost motion rate is less than 1.20%, the parasitic rotations of the motion stage (MS are in the order of 10−5 rad, and the parasitic translations of the three actuated stages (ASs are in the order of 10−4 of the beam length (less than 0.3% of the motion range, where the beam slenderness ratio is larger than 20. Furthermore, the nonlinear analytical models of the primary translations of the XYZ CPM, including the primary translations of the MS and the ASs, are derived and validated to provide a quick design synthesis. Moreover, two practical design schemes of the proposed XYZ CPM are discussed with consideration of the manufacturability. The practical designs enable the XYZ CPM to be employed in many applications such as micro-/nano-positioning, micro-/nano-manufacturing and micro-/nano-assembly. Finally, a spatial high-precision translational system is presented based on the practical design schemes, taking the actuator and sensor integration into account.

  11. Micro/Nano Multilayered Scaffolds of PLGA and Collagen by Alternately Electrospinning for Bone Tissue Engineering

    Science.gov (United States)

    Kwak, Sanghwa; Haider, Adnan; Gupta, Kailash Chandra; Kim, Sukyoung; Kang, Inn-Kyu

    2016-07-01

    The dual extrusion electrospinning technique was used to fabricate multilayered 3D scaffolds by stacking microfibrous meshes of poly(lactic acid-co-glycolic acid) (PLGA) in alternate fashion to micro/nano mixed fibrous meshes of PLGA and collagen. To fabricate the multilayered scaffold, 35 wt% solution of PLGA in THF-DMF binary solvent (3:1) and 5 wt% solution of collagen in hexafluoroisopropanol (HFIP) with and without hydroxyapatite nanorods (nHA) were used. The dual and individual electrospinning of PLGA and collagen were carried out at flow rates of 1.0 and 0.5 mL/h, respectively, at an applied voltage of 20 kV. The density of collagen fibers in multilayered scaffolds has controlled the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. The homogeneous dispersion of glutamic acid-modified hydroxyapatite nanorods (nHA-GA) in collagen solution has improved the osteogenic properties of fabricated multilayered scaffolds. The fabricated multilayered scaffolds were characterized using FT-IR, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). The scanning electron microscopy (FE-SEM) was used to evaluate the adhesion and spreads of MC3T3-E1 cells on multilayered scaffolds. The activity of MC3T3-E1 cells on the multilayered scaffolds was evaluated by applying MTT, alkaline phosphatase, Alizarin Red, von Kossa, and cytoskeleton F-actin assaying protocols. The micro/nano fibrous PLGA-Col-HA scaffolds were found to be highly bioactive in comparison to pristine microfibrous PLGA and micro/nano mixed fibrous PLGA and Col scaffolds.

  12. Generation of Hierarchically Ordered Structures on a Polymer Film by Electrohydrodynamic Structure Formation.

    Science.gov (United States)

    Tian, Hongmiao; Shao, Jinyou; Hu, Hong; Wang, Li; Ding, Yucheng

    2016-06-29

    The extensive applications of hierarchical structures in optoelectronics, micro/nanofluidics, energy conservation, etc., have led to the development of a variety of approaches for their fabrication, which can be categorized as bottom-up or top-down strategies. Current bottom-up and top-down strategies bear a complementary relationship to each other due to their processing characteristics, i.e., the advantages of one method correspond to the disadvantages of the other, and vice versa. Here we propose a novel method based on electrohydrodynamic structure formation, aimed at combining the main advantages of the two strategies. The method allows the fabrication of a hierarchically ordered structure with well-defined geometry and high mechanical durability on a polymer film, through a simple and low-cost process also suitable for mass-production. In this approach, upon application of an electric field between a template and a substrate sandwiching an air gap and a polymer film, the polymer is pulled toward the template and further flows into the template cavities, resulting in a hierarchical structure with primary and secondary patterns determined by electrohydrodynamic instability and by the template features, respectively. In this work, the fabrication of a hierarchical structure by electrohydrodynamic structure formation is studied using numerical simulations and experimental tests. The proposed method is then employed for the one-step fabrication of a hierarchical structure exhibiting a gradual transition in the periodicity of the primary structure using a slant template and a flat polymer film, which presents an excellent performance on controllable wettability.

  13. Report on best practice for micro/nano replication process data acquisition systems

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul

    The main objective of this deliverable is to collect detailed description on the best practice for micro/ nano replication process data acquisition system. In particular the following aspects are summed up in the deliverable: Process requirements for COTECH demonstrators General description...... of the processes and process parameters State-of-the-art process control and data acquisition systems Sensor integration in COTECH tools Expected COTECH improvement in process control and data acquisition system Information provide by this deliverable will be used as input to the COTECH process control system...

  14. Copper oxide assisted cysteine hierarchical structures for immunosensor application

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Chandra Mouli [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Sumana, Gajjala, E-mail: sumanagajjala@gmail.com [Biomedical Instrumentation Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Tiwari, Ida [Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India)

    2014-09-08

    The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constant of 3.38 × 10{sup −4 }cm s{sup −1}. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.

  15. Leveraging hierarchical population structure in discrete association studies.

    Directory of Open Access Journals (Sweden)

    Jonathan Carlson

    Full Text Available Population structure can confound the identification of correlations in biological data. Such confounding has been recognized in multiple biological disciplines, resulting in a disparate collection of proposed solutions. We examine several methods that correct for confounding on discrete data with hierarchical population structure and identify two distinct confounding processes, which we call coevolution and conditional influence. We describe these processes in terms of generative models and show that these generative models can be used to correct for the confounding effects. Finally, we apply the models to three applications: identification of escape mutations in HIV-1 in response to specific HLA-mediated immune pressure, prediction of coevolving residues in an HIV-1 peptide, and a search for genotypes that are associated with bacterial resistance traits in Arabidopsis thaliana. We show that coevolution is a better description of confounding in some applications and conditional influence is better in others. That is, we show that no single method is best for addressing all forms of confounding. Analysis tools based on these models are available on the internet as both web based applications and downloadable source code at http://atom.research.microsoft.com/bio/phylod.aspx.

  16. Hierarchical tubular structures grown from the gel/liquid interface.

    Science.gov (United States)

    Steenbjerg Ibsen, Casper Jon; Mikladal, Bjørn Fridur; Bjørnholt Jensen, Uffe; Birkedal, Henrik

    2014-12-01

    Three dimensional hierarchical materials are widespread in nature but are difficult to synthesize by using self-assembly/organization. Here, we employ a gel-liquid interface to obtain centimeter-long ∼100 μm diameter tubes with complex mineral wall structures that grow from the interface into solution. The gel, made from gelatin, is loaded with metal chloride salt, whereas the solution is a high pH anion source. Tubes were obtained with a range of cations (Ca(2+) , Sr(2+) , Ba(2+) , Cu(2+) , and Zn(2+) ) and anions (CO3 (2-) and PO4 (3-) ). The crystalline phases found in the tube walls corresponded to expectations from solution chemistries and phase solubilities. The growth mechanism is found to be akin to that of chemical gardens. The divalent cations modify the strength of the gelatin gel in a manner that involves not only simple electrostatic screening, but also ion-specific effects. Thus, tubes were not obtained for those ions and/or concentrations that significantly changed the gel's mechanical structure. At high Cu(2+) loading, for example, vertical convection bands, not Liesegang bands, were observed in the gels.

  17. Hierarchical object parsing from structured noisy point clouds.

    Science.gov (United States)

    Barbu, Adrian

    2013-07-01

    Object parsing and segmentation from point clouds are challenging tasks because the relevant data is available only as thin structures along object boundaries or other features, and is corrupted by large amounts of noise. To handle this kind of data, flexible shape models are desired that can accurately follow the object boundaries. Popular models such as active shape and active appearance models (AAMs) lack the necessary flexibility for this task, while recent approaches such as the recursive compositional models make model simplifications to obtain computational guarantees. This paper investigates a hierarchical Bayesian model of shape and appearance in a generative setting. The input data is explained by an object parsing layer which is a deformation of a hidden principal component analysis (PCA) shape model with Gaussian prior. The paper also introduces a novel efficient inference algorithm that uses informed data-driven proposals to initialize local searches for the hidden variables. Applied to the problem of object parsing from structured point clouds such as edge detection images, the proposed approach obtains state-of-the-art parsing errors on two standard datasets without using any intensity information.

  18. Curved hierarchically micro-micro structured polypropylene surfaces by injection molding

    Science.gov (United States)

    Mielonen, K.; Suvanto, M.; Pakkanen, T. A.

    2017-01-01

    Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

  19. Transfer printing of 3D hierarchical gold structures using a sequentially imprinted polymer stamp

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Fengxiang; Low, Hong Yee [Institute of Materials Research and Engineering, A-STAR - Agency for Science, Technology and Research, 3 Research Link, 117602 (Singapore)], E-mail: hy-low@imre.a-star.edu.sg

    2008-10-15

    Complex three-dimensional (3D) hierarchical structures on polymeric materials are fabricated through a process referred to as sequential imprinting. In this work, the sequentially imprinted polystyrene film is used as a soft stamp to replicate hierarchical structures onto gold (Au) films, and the Au structures are then transferred to a substrate by transfer printing at an elevated temperature and pressure. Continuous and isolated 3D structures can be selectively fabricated with the assistance of thermo-mechanical deformation of the polymer stamp. Hierarchical Au structures are achieved without the need for a corresponding three-dimensionally patterned mold.

  20. Upconversion luminescence of lanthanide-doped mixed CaMoO4-CaWO4 micro-/nano-materials.

    Science.gov (United States)

    Liu, Jing; Kaczmarek, Anna M; Billet, Jonas; Van Driessche, Isabel; Van Deun, Rik

    2016-08-14

    Uniform mixed CaMoO4-CaWO4 micro-/nano-materials have been successfully synthesised by a facile hydrothermal method. The morphology of these upconversion materials could be changed to different shapes and the size could also be decreased from the micro- to nano-scale by varying the type of surfactant used. It was observed that before heat treatment, the materials show relatively weak green light emission under excitation at 975 nm, whereas after heat treatment, the intensity of the upconversion luminescence increases dramatically while the intensity of the red component decreases relatively. By adjusting the molybdate/tungstate ratio, it was found that the samples with a higher molybdate content have stronger luminescence properties. XRD measurements have been done to investigate the structure of the mixed CaMoO4-CaWO4 upconversion materials. The effect of heat treatment at different temperatures on the emission spectra and XRD patterns has also been studied. TG-DTA was used to further confirm the most suitable temperature for heat treatment. The luminescence lifetimes and CIE coordinates for these samples were also determined. Additionally it was found that Gd(3+) co-doping could further increase the upconversion luminescence from these mixed CaMoO4-CaWO4 materials. Finally, monitoring the upconversion luminescence intensity as a function of laser pump power confirmed the upconversion process to be a two-photon absorption mechanism.

  1. Developing Dynamic Virtual Environments Using Hierarchical, Tree-Structured Approach

    Directory of Open Access Journals (Sweden)

    Wan Mohd Rizhan Wan Idris

    2011-05-01

    Full Text Available Virtual reality (VR has been utilized in various applications such as in architecture, medicine, advertisement, business, entertainment, and education. In the world of simulation, VR software allows users to visualize, manipulate and interact with the computers and complex data. However, developing VR environments is costly and expensive. Highly-technical persons are needed to create the virtual objects from scratch. Once a virtual system is created, managing and modifying it creates further problems. There is a need for non-technical users to be able to create and modify their own virtual environments. This paper discusses a systematic technique to develop dynamic virtual environments and to manage virtual objects in their virtual environment. The technique is called hierarchical, tree-structured approach. To implement the technique, object-oriented programming language was used such as Java, Java 3D and Java Swing. For the usability and performance of the technique, a virtual environment has been created to become as case study. The tool has been perceived as an easy tool to use, especially for an environment in education.

  2. DEVELOPING DYNAMIC VIRTUAL ENVIRONMENTS USING HIERARCHICAL, TREE-STRUCTURED APPROACH

    Directory of Open Access Journals (Sweden)

    Wan Mohd Rizhan Wan Idris

    2015-10-01

    Full Text Available Virtual reality (VR has been utilized in various applications such as in architecture, medicine, advertisement, business, entertainment, and education. In the world of simulation, VR software allows users to visualize, manipulate and interact with the computers and complex data. However, developing VR environments is costly and expensive. Highly-technical persons are needed to create the virtual objects from scratch. Once a virtual system is created, managing and modifying it creates further problems. There is a need for non-technical users to be able to create and modify their own virtual environments. This paper discusses a systematic technique to develop dynamic virtual environments and to manage virtual objects in their virtual environment. The technique is called hierarchical, tree-structured approach. To implement the technique, object-oriented programming language was used such as Java, Java 3D and Java Swing. For the usability and performance of the technique, a virtual environment has been created to become as case study. The tool has been perceived as an easy tool to use, especially for an environment in education.

  3. SO2 Emissions in China - Their Network and Hierarchical Structures

    Science.gov (United States)

    Yan, Shaomin; Wu, Guang

    2017-04-01

    SO2 emissions lead to various harmful effects on environment and human health. The SO2 emission in China has significant contribution to the global SO2 emission, so it is necessary to employ various methods to study SO2 emissions in China with great details in order to lay the foundation for policymaking to improve environmental conditions in China. Network analysis is used to analyze the SO2 emissions from power generation, industrial, residential and transportation sectors in China for 2008 and 2010, which are recently available from 1744 ground surface monitoring stations. The results show that the SO2 emissions from power generation sector were highly individualized as small-sized clusters, the SO2 emissions from industrial sector underwent an integration process with a large cluster contained 1674 places covering all industrial areas in China, the SO2 emissions from residential sector was not impacted by time, and the SO2 emissions from transportation sector underwent significant integration. Hierarchical structure is obtained by further combining SO2 emissions from all four sectors and is potentially useful to find out similar patterns of SO2 emissions, which can provide information on understanding the mechanisms of SO2 pollution and on designing different environmental measure to combat SO2 emissions.

  4. Bayesian structural equation modeling method for hierarchical model validation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Xiaomo [Department of Civil and Environmental Engineering, Vanderbilt University, Box 1831-B, Nashville, TN 37235 (United States)], E-mail: xiaomo.jiang@vanderbilt.edu; Mahadevan, Sankaran [Department of Civil and Environmental Engineering, Vanderbilt University, Box 1831-B, Nashville, TN 37235 (United States)], E-mail: sankaran.mahadevan@vanderbilt.edu

    2009-04-15

    A building block approach to model validation may proceed through various levels, such as material to component to subsystem to system, comparing model predictions with experimental observations at each level. Usually, experimental data becomes scarce as one proceeds from lower to higher levels. This paper presents a structural equation modeling approach to make use of the lower-level data for higher-level model validation under uncertainty, integrating several components: lower-level data, higher-level data, computational model, and latent variables. The method proposed in this paper uses latent variables to model two sets of relationships, namely, the computational model to system-level data, and lower-level data to system-level data. A Bayesian network with Markov chain Monte Carlo simulation is applied to represent the two relationships and to estimate the influencing factors between them. Bayesian hypothesis testing is employed to quantify the confidence in the predictive model at the system level, and the role of lower-level data in the model validation assessment at the system level. The proposed methodology is implemented for hierarchical assessment of three validation problems, using discrete observations and time-series data.

  5. The Emergence of Hierarchical Structure in Human Language

    Directory of Open Access Journals (Sweden)

    Shigeru eMiyagawa

    2013-02-01

    Full Text Available We propose a novel account for the emergence of human language syntax. Like many evolutionary innovations, language arose from the adventitious combination of two pre-existing, simpler systems that had been evolved for other functional tasks. The first system, Type E(xpression, is found in birdsong, where it marks territory, mating availability, and similar ‘expressive’ functions. The second system, Type L(exical, has been suggestively found in non-human primate calls and in honeybee waggle dances, where it demarcates predicates with one or more ‘arguments,’ such as combinations of calls in monkeys or compass headings set to sun position in honeybees. We show that human language syntax is composed of two layers that parallel these two independently evolved systems: an E layer resembling the Type E system of birdsong and an L layer providing words. The existence of the E and L layers can be confirmed using standard linguistic methodology. Each layer, E and L, when considered separately, are characterizable as finite state systems, as observed in several non-human species. When the two systems are put together they interact, yielding the unbounded, non-finite state, hierarchical structure that serves as the hallmark of ful

  6. Dynamic substructure model for multiple impact responses of micro/nano piezoelectric precision drive system

    Institute of Scientific and Technical Information of China (English)

    SHEN YuNian; YIN XiaoChun

    2009-01-01

    A dynamic substructure technique which considers the electromechanlcal coupling effect of the PZT and the inertial effect of flexible components is presented to study the multiple impact dynamic be-havior of micro/nano piezoelectric impact drive systems. It can investigate the step-like motion of ob-ject body and the multiple impacts behaviors reasonably by the comparison of the experimental data and the numerical solution of the spring-mass model. It is expected to have higher accuracy in the numerical simulations of the motion and the responses, especially to high frequency pulse voltage excitations. The present dynamic substructure technique has firstly studied reasonably the propaga-tions of piezoelectric-induced transient waves and impact-induced transient waves. It is helpful to the failure analysis and the design of piezoelectric stack and flexible components. The present dynamic substructure technique can be applied to the transient dynamics optimization design and the precision control of the micro/nano piezoelectric impact drive systems.

  7. Preparation of micro/nano-fibrous brushite coating on titanium via chemical conversion for biomedical applications

    Science.gov (United States)

    Liu, Bing; Guo, Yong-yuan; Xiao, Gui-yong; Lu, Yu-peng

    2017-03-01

    Calcium phosphate coatings have been applied on the surface of Ti implants to realize better osseointegration. The formation of dicalcium phosphate dihydrate (CaHPO4·2H2O), mineralogically named brushite on pure Ti substrate has been investigated via chemical conversion method. Coating composition and microstructure have been investigated by X-ray diffractometer, Fourier transform infrared spectrometer and field emission scanning electron microscope. The results reveal that the coatings are composed of high crystalline brushite with minor scholzite (CaZn2(PO4)2·2H2O). A micro/nano-scaled fibrous morphology can be produced in the acidic chemical conversion bath with pH 5.00. The surface of the fibrous brushite coating exhibits high hydrophilicity and corrosion resistance in the simulated body fluid. The osteoblast cells grow and spread actively on the coated samples and the proliferation numbers and alkaline phosphate activities of the cells improve significantly compared to the uncoated Ti. It is suggested that the micro/nano-fibrous brushite coating can be a potential approach to improve the osteoinductivity and osteoconductivity of Ti implant, due to its similarity in morphology and dimension to inorganic components of biological hard tissues, and favorable responses to the osteoblasts.

  8. Nanorobotic System iTRo for Controllable 1D Micro/nano Material Twisting Test.

    Science.gov (United States)

    Lu, Haojian; Shang, Wanfeng; Wei, Xueyong; Yang, Zhan; Fukuda, Toshio; Shen, Yajing

    2017-06-08

    In-situ micro/nano characterization is an indispensable methodology for material research. However, the precise in-situ SEM twisting of 1D material with large range is still challenge for current techniques, mainly due to the testing device's large size and the misalignment between specimen and the rotation axis. Herein, we propose an in-situ twist test robot (iTRo) to address the above challenges and realize the precise in-situ SEM twisting test for the first time. Firstly, we developed the iTRo and designed a series of control strategies, including assembly error initialization, triple-image alignment (TIA) method for rotation axis alignment, deformation-based contact detection (DCD) method for sample assembly, and switch control for robots cooperation. After that, we chose three typical 1D material, i.e., magnetic microwire Fe74B13Si11C2, glass fiber, and human hair, for twisting test and characterized their properties. The results showed that our approach is able to align the sample to the twisting axis accurately, and it can provide large twisting range, heavy load and high controllability. This work fills the blank of current in-situ mechanical characterization methodologies, which is expected to give significant impact in the fundamental nanomaterial research and practical micro/nano characterization.

  9. Dynamic substructure model for multiple impact responses of micro/nano piezoelectric precision drive system

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A dynamic substructure technique which considers the electromechanical coupling effect of the PZT and the inertial effect of flexible components is presented to study the multiple impact dynamic be- havior of micro/nano piezoelectric impact drive systems. It can investigate the step-like motion of ob- ject body and the multiple impacts behaviors reasonably by the comparison of the experimental data and the numerical solution of the spring-mass model. It is expected to have higher accuracy in the numerical simulations of the motion and the responses, especially to high frequency pulse voltage excitations. The present dynamic substructure technique has firstly studied reasonably the propaga- tions of piezoelectric-induced transient waves and impact-induced transient waves. It is helpful to the failure analysis and the design of piezoelectric stack and flexible components. The present dynamic substructure technique can be applied to the transient dynamics optimization design and the precision control of the micro/nano piezoelectric impact drive systems.

  10. Provision of micro-nano bacterial cellulose as bio plastic filler by sonication method

    Science.gov (United States)

    Maryam; Rahmad, D.; Yunizurwan; Kasim, A.; Novelina; Emriadi

    2017-07-01

    Research and development of bioplastic has increased recently as a solution for substitution of conventional plastic which have many negative impacts to environment. However, physical properties and mechanical properties of its still lower than conventional plastic. An alternative solution for that problem is by using fillers that can increase the strength. Bacterial cellulose is considered as potential source for filler, but still need to be explored more. The privileges of bacterial cellulose are easy to get and does not have lignin, pectin, and hemicelluloses which are impurities in other celluloses. This research focused on gaining bacterial cellulose in micro-nano particle form and its impact on increasing the strength of bio plastic. Ultrasonication has been used as method to form micro-nano particle from bacterial cellulose. The result showed this method may form the particle size of bacterial cellulose approximately ± 3μm. Next step, after getting ± 3μm particle of bacterial cellulose, is making bio plastic with casting method by adding 1% of bacterial cellulose, from the total material in making bio plastic. Physical characteristic of the bio plastic which are tensile strength 11.85 MPa, modulus young 3.13 MPa, elongation 4.11% and density 0.42 g/cm3. The numbers of physical properties showwthat, by adding 1% of bacterial cellulose, the strength of bio plastic was significantly increase, even value of tensile strength has complied the international standard for bio plastic.

  11. Fabrication of micro-nano composite textured surface for slurry sawn mc-Si wafers cell

    Science.gov (United States)

    Niu, Y. C.; liu, Z.; Ren, X. K.; Liu, X. J.; Liu, H. T.; Jiang, Y. S.

    2017-01-01

    In order to enhance the PV efficiency of the cell made from slurry sawn (SS) mc-Si wafers, using a Ag-assisted electroless etching (AgNO3+HF+H2O2) combined with an auxiliary etching (HF+HNO3) the RENA textured SS mc-Si wafers (called as RENA wafers) were further textured (nano pores were formed on the original micro pits) to change into micro-nano composite textured wafers (called as MN-RENA wafers). The solar cells made from the MN-RENA wafers had a better PV efficiency than that of RENA wafers. This is mainly attributed to the higher light-trapping of the micro-nano composite texture. The nano size texture enhanced the light-trap of wafer surface and, at the same time, the micro size texture maintained the light-trap uniformity of different gains of RENA wafer. However, there still exist a potential for optimization, such as, the SiNx passviation coating should be improved to be deposited more uniformly in order to passivate the bottom of pits better and to reduce the reflectance of the obtuse tips of pits.

  12. HIERARCHICAL STRUCTURE IN ADL AND IADL - ANALYTICAL ASSUMPTIONS AND APPLICATIONS FOR CLINICIAN AND RESEARCHERS

    NARCIS (Netherlands)

    KEMPEN, GIJM; MYERS, AM; POWELL, LE

    1995-01-01

    The results of a Canadian study have shown that a set of 12 (I)ADL items did not meet the criteria of Guttman's scalogram program, questioning the assumption of hierarchical ordering. In this article, the hierarchical structure of (I)ADL items from the Canadian elderly sample is retested with anothe

  13. Hierarchical modeling and its numerical implementation for layered thin elastic structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin-Rae [Hongik University, Sejong (Korea, Republic of)

    2017-05-15

    Thin elastic structures such as beam- and plate-like structures and laminates are characterized by the small thickness, which lead to classical plate and laminate theories in which the displacement fields through the thickness are assumed linear or higher-order polynomials. These classical theories are either insufficient to represent the complex stress variation through the thickness or may encounter the accuracy-computational cost dilemma. In order to overcome the inherent problem of classical theories, the concept of hierarchical modeling has been emerged. In the hierarchical modeling, the hierarchical models with different model levels are selected and combined within a structure domain, in order to make the modeling error be distributed as uniformly as possible throughout the problem domain. The purpose of current study is to explore the potential of hierarchical modeling for the effective numerical analysis of layered structures such as laminated composite. For this goal, the hierarchical models are constructed and the hierarchical modeling is implemented by selectively adjusting the level of hierarchical models. As well, the major characteristics of hierarchical models are investigated through the numerical experiments.

  14. D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure

    Science.gov (United States)

    Suhaibah, A.; Uznir, U.; Anton, F.; Mioc, D.; Rahman, A. A.

    2016-06-01

    Locating and analysing the location of new stores or outlets is one of the common issues facing retailers and franchisers. This is due to assure that new opening stores are at their strategic location to attract the highest possible number of customers. Spatial information is used to manage, maintain and analyse these store locations. However, since the business of franchising and chain stores in urban areas runs within high rise multi-level buildings, a three-dimensional (3D) method is prominently required in order to locate and identify the surrounding information such as at which level of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However, with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results are presented in this paper. Another advantage of this structure is that it also offers a minimal overlap and coverage among nodes which can reduce repetitive data entry.

  15. Facile Fabrication of a Hierarchical Superhydrophobic Coating with Aluminate Coupling Agent Modified Kaolin

    Directory of Open Access Journals (Sweden)

    Hui Li

    2013-01-01

    Full Text Available A superhydrophobic coating was fabricated from the dispersion of unmodified kaolin particles and aluminate coupling agent in anhydrous ethanol. Through surface modification, water contact angle of the coating prepared by modified kaolin particles increased dramatically from 0° to 152°, and the sliding angle decreased from 90° to 3°. Scanning electron microscopy was used to examine the surface morphology. A structure composed of micro-nano hierarchical component, combined with the surface modification by aluminate coupling agent which reduced the surface energy greatly, was found to be responsible for the superhydrophobicity. The method adopted is relatively simple, facile, and cost-effective and can potentially be applied to large water-repellent surface coatings.

  16. Research on critical technology of micro/nano bioparticles manipulation platform based on light-induced dielectrophoresis

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    On the basis of the research on the status and problems of micro/nano bio-particles manipulation using dielectrophoresis, the theoretical basis and the model simulation of micro/nano bio-particles manipu-lation using light-induced dielectrophoresis were discussed. The space distribution of electric field and dielectrophoresis forces in different heights were also obtained. On this basis, the core component of the micro manipulation system, that is, photoconductive layer of the chip, was completed in the mate-rial selection, fabricating process and performance analysis testing. Then the voltage drop of the sus-pension and the effective voltage frequency spectrum were obtained. Finally, by combining the machine vision detection with real-time tracking system, the micro/nano bio-particles manipulation platform based on the light-induced dielectrophoreisis was established, and then the manipulations for micro/nano bio-particles, such as quick collection, transport, separation, were implemented. This provided a basis for rapid, accurate, and low-cost detection of serious diseases based on the micro-fluidic biochip and early diagnosis.

  17. Building Algebra Testlets: A Comparison of Hierarchical and Linear Structures.

    Science.gov (United States)

    Wainer, Howard; And Others

    1991-01-01

    Hierarchical (adaptive) and linear methods of testlet construction were compared. The performance of 2,080 ninth and tenth graders on a 4-item testlet was used to predict performance on the entire test. The adaptive test was slightly superior as a predictor, but the cost of obtaining that superiority was considerable. (SLD)

  18. Building Algebra Testlets: A Comparison of Hierarchical and Linear Structures.

    Science.gov (United States)

    Wainer, Howard; And Others

    1991-01-01

    Hierarchical (adaptive) and linear methods of testlet construction were compared. The performance of 2,080 ninth and tenth graders on a 4-item testlet was used to predict performance on the entire test. The adaptive test was slightly superior as a predictor, but the cost of obtaining that superiority was considerable. (SLD)

  19. Hierarchical Data Structures in Adventure Education and Therapy

    Science.gov (United States)

    Russell, Keith; Sibthorp, Jim

    2004-01-01

    Hierarchical linear modeling (HIM) is an approach used in data analysis to better understand how program outcomes are affected by the "nested" nature of data collected in many studies. An outcome can be considered variables such as an individual's self-efficacy, social skills, or more targeted outcomes such as demonstrated reading and mathematical…

  20. In-situ preparation of Fe2O3 hierarchical arrays on stainless steel substrate for high efficient catalysis

    Science.gov (United States)

    Yang, Zeheng; Wang, Kun; Shao, Zongming; Tian, Yuan; Chen, Gongde; Wang, Kai; Chen, Zhangxian; Dou, Yan; Zhang, Weixin

    2017-02-01

    Hierarchical array catalysts with micro/nano structures on substrates not only possess high reactivity from large surface area and suitable interface, but intensify mass transfer through shortening the diffusion paths of both reactants and products for high catalytic efficiency. Herein, we first demonstrate fabrication of Fe2O3 hierarchical arrays grown on stainless-steel substrates via in-situ hydrothermal chemical oxidation followed by heat treatment in N2 atmosphere. As a Fenton-like catalyst, Fe2O3 hierarchical arrays exhibit excellent catalytic activity and life cycle performance for methylene blue (MB) dye degradation in aqueous solution in the presence of H2O2. The Fe2O3 catalyst with unique hierarchical structures and efficient transport channels, effectively activates H2O2 to generate large quantity of •OH radicals and highly promotes reaction kinetics between MB and •OH radicals. Immobilization of hierarchical array catalysts on stainless-steel can prevent particles agglomeration, facilitate the recovery and reuse of the catalysts, which is expected promising applications in wastewater remediation.

  1. Free vibration, wave propagation and tension analyses of a sandwich micro/nano rod subjected to electric potential using strain gradient theory

    Science.gov (United States)

    Arefi, Mohammad; Zenkour, Ashraf M.

    2016-11-01

    Strain gradient theory is used to study free vibration, wave propagation and tension analyses of a sandwich micro/nano rod made of piezoelectric materials under electric potential. The structure is resting on a Pasternak’s foundation medium. Love’s rod model is used for derivation of displacement field. The piezoelectric face sheets are subjected to two-dimensional electric potential including an applied voltage at top of plate and a cosine term along the thickness direction. Hamilton’s principle is used to derive governing equations of motion in terms of axial displacement and electric potential. Three distinct behaviors of the present problem including free vibration, wave propagation and tension analyses are performed. Some important numerical results are presented in detail to capture the effect of materials length scales and applied voltage on the different behaviors of microrod.

  2. Web Application for Hierarchical Organizational Structure Optimization – Human Resource Management Case Study

    Directory of Open Access Journals (Sweden)

    Kofjač Davorin

    2015-08-01

    Full Text Available Background and Purpose: In a complex strictly hierarchical organizational structure, undesired oscillations may occur, which have not yet been adequately addressed. Therefore, parameter values, which define fluctuations and transitions from one state to another, need to be optimized to prevent oscillations and to keep parameter values between lower and upper bounds. The objective was to develop a simulation model of hierarchical organizational structure as a web application to help in solving the aforementioned problem.

  3. Report on best practice for micro/nano replication process data acquisition systems

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul

    The main objective of this deliverable is to collect detailed description on the best practice for micro/ nano replication process data acquisition system. In particular the following aspects are summed up in the deliverable: Process requirements for COTECH demonstrators General description...... of the processes and process parameters State-of-the-art process control and data acquisition systems Sensor integration in COTECH tools Expected COTECH improvement in process control and data acquisition system Information provide by this deliverable will be used as input to the COTECH process control system....... This report presents the important processes and process parameters required for the realization of COTECH demonstrator. It also presents the cutting edge sensor systems used for different process and set a guideline to integrate sensors in COTECH tools....

  4. Review on Impedance Detection of Cellular Responses in Micro/Nano Environment

    Directory of Open Access Journals (Sweden)

    Kin Fong Lei

    2014-01-01

    Full Text Available In general, cell culture-based assays, investigations of cell number, viability, and metabolic activities during culture periods, are commonly performed to study the cellular responses under various culture conditions explored. Quantification of cell numbers can provide the information of cell proliferation. Cell viability study can understand the percentage of cell death under a specific tested substance. Monitoring of the metabolic activities is an important index for the study of cell physiology. Based on the development of microfluidic technology, microfluidic systems incorporated with impedance measurement technique, have been reported as a new analytical approach for cell culture-based assays. The aim of this article is to review recent developments on the impedance detection of cellular responses in micro/nano environment. These techniques provide an effective and efficient technique for cell culture-based assays.

  5. Internal distribution of micro- / nano-sized inorganic particles and their cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Shigeaki; Iwadera, Nobuki; Esaki, Mitsue; Kida, Ikuhiro; Akasaka, Tsukasa; Uo, Motohiro; Yawaka, Yasutaka; Watari, Fumio [Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586 (Japan); Mutoh, Mami [School of Dental Medicine, Hokkaido University, Sapporo 060-8586 (Japan); Morita, Manabu [Department of Oral Health, Okayama University Graduate School of Medicine, Dentisity and Pharmaceutical Science, Okayama 700-8525 (Japan); Haneda, Koichi [Department of Information Technology and Electronics, Senshu University of Ishinomaki, Ishinomaki 986-8580 (Japan); Yonezawa, Tetsu, E-mail: sabe@den.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)

    2011-10-29

    Nano-sized materials have received much attention lately, both in terms of their multiple applications and their biocompatibility. From both viewpoints, understanding the biodistribution of administered nano-materials is very important. In this study, we succeeded in visualizing the biodistribution of administered nano-materials using a scanning X-ray analytical microscope and magnetic resonance imaging method. Quantitative observation was carried out by inductively coupled plasma - atomic emission spectroscopy. We observed that the administered nano-particles accumulated in the liver, lung and spleen of mice. To estimate their cytocompatibility, the nano-particles were exposed to human liver cells. The results suggested that the micro-/ nano- particles have good cytocompatibility, except for copper oxide nano-particles.

  6. A novel flexure-based microgripper with double amplification mechanisms for micro/nano manipulation

    Science.gov (United States)

    Sun, Xiantao; Chen, Weihai; Tian, Yanling; Fatikow, Sergej; Zhou, Rui; Zhang, Jianbin; Mikczinski, Manuel

    2013-08-01

    This paper describes the design, modeling, and testing of a novel flexure-based microgripper for a large jaw displacement with high resolution. Such a microgripper is indispensable in micro/nano manipulation. In achieving a large jaw displacement, double amplification mechanisms, namely, Scott-Russell mechanism and leverage mechanism arranged in series, are utilized to overcome the limited output of microgrippers driven by piezoelectric actuators. The mechanical performance of the microgripper is analyzed using the pseudo rigid body model approach. Finite element analysis is conducted to evaluate the performance and validate the established models for further optimum design of the microgripper. The prototype of the developed microgripper is fabricated, with which experimental tests are carried out. The experimental results show that the developed microgripper is capable of handling various sized micro-objects with a maximum jaw displacement of 134 μm and a high amplification ratio of 15.5.

  7. On the similarities between micro/nano lithography and topology optimization projection methods

    DEFF Research Database (Denmark)

    Jansen, Miche; Lazarov, Boyan Stefanov; Schevenels, Mattias;

    2013-01-01

    The aim of this paper is to incorporate a model for micro/nano lithography production processes in topology optimization. The production process turns out to provide a physical analogy for projection filters in topology optimization. Blueprints supplied by the designers cannot be directly used...... projection filter can be used to account for uncertainties due to lithographic production processes which results in manufacturable blueprint designs and eliminates the need for subsequent corrections....... as inputs to lithographic processes due to the proximity effect which causes rounding of sharp corners and geometric interaction of closely spaced design elements. Therefore, topology optimization is applied as a tool for proximity effect correction. Furthermore, it is demonstrated that the robust...

  8. Enhanced copper micro/nano-particle mixed paste sintered at low temperature for 3D interconnects

    Science.gov (United States)

    Dai, Y. Y.; Ng, M. Z.; Anantha, P.; Lin, Y. D.; Li, Z. G.; Gan, C. L.; Tan, C. S.

    2016-06-01

    An enhanced copper paste, formulated by copper micro- and nano-particles mixture, is reported to prevent paste cracking and obtain an improved packing density. The particle mixture of two different sizes enables reduction in porosity of the micro-paste and resolves the cracking issue in the nano-paste. In-situ temperature and resistance measurements indicate that the mixed paste has a lower densification temperature. Electrical study also shows a ˜12× lower sheet resistance of 0.27 Ω/sq. In addition, scanning electron microscope image analysis confirms a ˜50% lower porosity, which is consistent with the thermal and electrical results. The 3:1 (micro:nano, wt. %) mixed paste is found to have the strongest synergistic effect. This phenomenon is discussed further. Consequently, the mixed paste is a promising material for potential low temperature 3D interconnects fabrication.

  9. MICRO/NANO-MACHINING ON SILICON SURFACE WITH A MODIFIED ATOMIC FORCE MICROSCOPE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To understand the deformation and removal mechanism of material on nano-scale and at ultralow loads, a systemic study on AFM micro/nano-machining on single crystal silicon is conducted. The results indicate that AFM nanomachining has a precisely dimensional controllability and a good surface quality on nanometer scale. A SEM is adopted to observe nano-machined region and chips, the results indicate that the material removal mechanisms change with the applied normal load. An XPS is used to analyze the changes of chemical composition inside and outside the nano-machined region respectively. The nano-indentation which is conducted with the same AFM diamond tip on the machined region shows a big discrepancy compared with that on the macro-scale. The calculated results show higher nano-hardness and elastic modulus than normal values. This phenomenon can be regarded as the indentation size effect(ISE).

  10. Two-Dimensional Porous Micro/Nano Metal Oxides Templated by Graphene Oxide.

    Science.gov (United States)

    Cao, Hailiang; Zhou, Xufeng; Zheng, Chao; Liu, Zhaoping

    2015-06-10

    Novel two-dimensional (2D) porous metal oxides with micro-/nanoarchitecture have been successfully fabricated using graphene oxide (GO) as a typical sacrificial template. GO as a 2D template ensures that the growth and fusion of metal oxides nanoparticles is restricted in the 2D plane. A series of metal oxides (NiO, Fe2O3, Co3O4, Mn2O3, and NiFe2O4) with similar nanostructure were investigated using this simple method. Some of these special nanostructured materials, such as NiO, when being used as anode for lithium-ion batteries, can exhibit high specific capacity, good rate performance, and cycling stability. Importantly, this strategy of creating a 2D porous micro/nano architecture can be easily extended to controllably synthesize other binary/polynary metal oxides nanostructures for lithium-ion batteries or other applications.

  11. Environmental Assessment of Micro/Nano Production in a Life Cycle Perspective

    DEFF Research Database (Denmark)

    Olsen, Stig Irving; Jørgensen, Michael Søgaard

    2006-01-01

    on a joint effort in manufacturing engineering and environmental assessment for eco efficiency improvement. A review of knowledge and studies on environmental assessments in the micro/nano technology area is performed and will be used to further detail the general framework for assessment outlined above...... LCA” may be useful because future changes are taken into account. However, it still does not suffice for emerging technologies. In a recent “Green Technology Foresight” project a methodology was developed based on five elements: Life-cycle thinking, systems approach, a broad dialogue based...... understanding of the environment, precaution as a principle and finally, prevention as preferred strategy. When assessing emerging technologies three levels should be considered. First order effects are connected directly to production, use and disposal. Second order are effects from interaction with other...

  12. Heat transport in polymer thin films for micro/nano-manufacturing

    Science.gov (United States)

    Hung, Ming-Tsung

    The rapid growth in micro/nanotechnology has opened a great opportunity for polymer thin films and polymer nanocomposites. Thermal management or thermal effects in those applications need to be carefully examined. For example, the local heating in electron-beam lithography, emersion lithography, and scanning near field optical lithography may cause the degradation of photoresists and reduce the resolution. The development of many organic electronics, polymer micro-electro-mechanical-systems (MEMS) devices, and polymer nanocomposites may require the knowledge of heat transport in micro/nano-sized polymers. Thermolithography, a novel lithography, uses controlled localized heating to transfer patterns and requires the thermal conductivity data to control. It is of considerable scientific and technological interests for study heat transport in polymer thin films. Unlike bulk polymers that can be measured using commercially available instruments, polymer thin films are difficult to measure. In this manuscript, we develop the measurement techniques suitable for measuring thermal conductivity of polymer thin films and polymer nanocomposites. Using a microfabricated membrane-based device, we study the heat conduction in photoresists at difference process stages. This data is used in our thermolithography study, where we use microheater to study the kinetic of crosslinking reaction of photoresist. The feasibility of thermolithography and potential three dimensional micro/nano-fabrication is presented. The uniqueness of thermolithography is also demonstrated by patterning amorphous fluoropolymers. A modified hot-wire technique is used to measure the thermal conductivity of graphite nanoplatelet (GNP) reinforced nanocomposites, one of the promising candidates for multifunctional materials. Thermal interface resistance in GNP nanocomposites is investigated, which shows a strong effect on energy transport in the nanocomposites and can be diminished through surface treatment.

  13. Resolution of Singularities Introduced by Hierarchical Structure in Deep Neural Networks.

    Science.gov (United States)

    Nitta, Tohru

    2016-06-30

    We present a theoretical analysis of singular points of artificial deep neural networks, resulting in providing deep neural network models having no critical points introduced by a hierarchical structure. It is considered that such deep neural network models have good nature for gradient-based optimization. First, we show that there exist a large number of critical points introduced by a hierarchical structure in deep neural networks as straight lines, depending on the number of hidden layers and the number of hidden neurons. Second, we derive a sufficient condition for deep neural networks having no critical points introduced by a hierarchical structure, which can be applied to general deep neural networks. It is also shown that the existence of critical points introduced by a hierarchical structure is determined by the rank and the regularity of weight matrices for a specific class of deep neural networks. Finally, two kinds of implementation methods of the sufficient conditions to have no critical points are provided. One is a learning algorithm that can avoid critical points introduced by the hierarchical structure during learning (called avoidant learning algorithm). The other is a neural network that does not have some critical points introduced by the hierarchical structure as an inherent property (called avoidant neural network).

  14. Direct writing of micro/nano-scale patterns by means of particle lens arrays scanned by a focused diode pumped Nd:YVO4 laser

    Science.gov (United States)

    Pena, Ana; Wang, Zengbo; Whitehead, David; Li, Lin

    2010-11-01

    A practical approach to a well-known technique of laser micro/nano-patterning by optical near fields is presented. It is based on surface patterning by scanning a Gaussian laser beam through a self-assembled monolayer of silica micro-spheres on a single-crystalline silicon (Si) substrate. So far, the outcome of this kind of near-field patterning has been related to the simultaneous, parallel surface-structuring of large areas either by top hat or Gaussian laser intensity distributions. We attempt to explore the possibility of using the same technique in order to produce single, direct writing of features. This could be of advantage for applications in which only some areas need to be patterned (i.e. local area selective patterning) or single lines are required (e.g. a particular micro/nano-fluidic channel). A diode pumped Nd:YVO4 laser system (wavelength of 532 nm, pulse duration of 8 ns, repetition rate of 30 kHz) with a computer-controlled 3 axis galvanometer beam scanner was employed to write user-defined patterns through the particle lens array on the Si substrate. After laser irradiation, the obtained patterns which are in the micro-scale were composed of sub-micro/micro-holes or bumps. The micro-pattern resolution depends on the dimension of both the micro-sphere’s diameter and the beam’s spot size. The developed technique could potentially be employed to fabricate photonic crystal structures mimicking nature’s butterfly wings and anti-reflective “moth eye” arrays for photovoltaic cells.

  15. The structure of dust aggregates in hierarchical coagulation

    CERN Document Server

    Dominik, Carsten; Borel, Herman

    2016-01-01

    Dust coagulation in interstellar space and protoplanetary disks is usually treated as one of 2 extreme cases: Particle-Cluster Aggregation and Cluster-Cluster Aggregation. In this paper we study the process of hierarchical growth, where aggregates are built from significantly smaller aggregates (but not monomers). We show that this process can be understood as a modified, PCA-like process that produces porous, but non-fractal particles whose filling factor is chiefly determined by the porosity of the building blocks. We also show that in a coagulation environment where relative velocities are driven by turbulence, a logarithmically flat mass distribution (equal mass per mass decade) as it is typically found in environments where fragmentation replenishes small grains, leads to a situation where small particles and aggregates dominate the growth of large ones. Therefore, in such environments, hierarchical growth should be seen as the norm. Consequently, we predict that the aggregates in such environments are n...

  16. Quasar Evolution Driven by Galaxy Encounters in Hierarchical Structures

    CERN Document Server

    Menci, N; Fontana, A; Giallongo, E; Poli, F; Vittorini, V

    2003-01-01

    We link the evolution of the galaxies in the hierarchical clustering scenario with the changing accretion rates of cold gas onto the central massive black holes that power the quasars. We base on galaxy interactions as main triggers of accretion; the related scaling laws are taken up from Cavaliere & Vittorini (2000), and grafted to a semi-analytic code for galaxy formation. As a result, at high $z$ the protogalaxies grow rapidly by hierarchical merging; meanwhile, much fresh gas is imported and also destabilized, so the holes are fueled at their full Eddington rates. At lower $z$ the galactic dynamical events are mostly encounters in hierarchically growing groups; now the refueling peters out, as the residual gas is exhausted while the destabilizing encounters dwindle. So, with no parameter tuning other than needed for stellar observables, our model uniquely produces at $z>3$ a rise, and at $z\\lesssim 2.5 $ a decline of the bright quasar population as steep as observed. In addition, our results closely f...

  17. Constrained hierarchical least square nonlinear equation solvers. [for indefinite stiffness and large structural deformations

    Science.gov (United States)

    Padovan, J.; Lackney, J.

    1986-01-01

    The current paper develops a constrained hierarchical least square nonlinear equation solver. The procedure can handle the response behavior of systems which possess indefinite tangent stiffness characteristics. Due to the generality of the scheme, this can be achieved at various hierarchical application levels. For instance, in the case of finite element simulations, various combinations of either degree of freedom, nodal, elemental, substructural, and global level iterations are possible. Overall, this enables a solution methodology which is highly stable and storage efficient. To demonstrate the capability of the constrained hierarchical least square methodology, benchmarking examples are presented which treat structure exhibiting highly nonlinear pre- and postbuckling behavior wherein several indefinite stiffness transitions occur.

  18. Reversible oleophobic/philic conversion properties in micro-nano Si-Ti composite coatings under UV irradiation%光控亲/疏油可逆转换的硅钛复合微纳米结构涂层研究∗

    Institute of Scientific and Technical Information of China (English)

    郭婷; 白瑞雪; 张青; 李伟; 童志平; 孟涛

    2015-01-01

    以简便价廉的方法制备出一种新型氟试剂修饰的SiO2-TiO2复合微纳米结构涂层。采用场发射扫描电子显微镜(FE-SEM)、X射线光电子能谱(XPS)和油接触角测试等方法对涂层进行了表征和测试。研究结果显示,该涂层具备良好的UV光驱动亲/疏油可逆转换特性,最初为疏油性(90°),光照后变得相对亲油(24°),黑暗放置后恢复疏油性,且经5次反复循环无明显衰减。与单纯纳米 TiO2涂层相比,复合涂层表面油浸润性的转变因微纳米结构的存在而显著强化,且随着Si O 2微球直径的增大,其亲/疏油效果得到增强。以上研究为亲/疏油可逆转换智能材料的设计提供了新的方法和借鉴。%A new type of fluorine modified micro-nano SiO2-TiO2 composite coating has been prepared though a convenient and low-cost method.Field emission scanning electron microscopy (FE-SEM),X-ray photoelectron spectroscopy (XPS)and oil contact angle were used to characterize the composite coatings.The results con-firmed the composite coating with repeated and reversible oleophobic/philic conversion properties (90-24°), which responded to cycles of UV irradiation and dark storage.Such switch can be safety performed during five continuous cycles without apparent attenuation.Compared with the single-scale nanostucture,the hierarchical micro-nano structure was demonstrated to play a key role in the improvement of the oleophobic/philic variation. Under the test range,the bigger the SiO2 microsphere is,the larger variation is obtained.These findings offer a new method for the design of smart materials with switchable oil wettability.

  19. INFOGRAPHIC MODELING OF THE HIERARCHICAL STRUCTURE OF THE MANAGEMENT SYSTEM EXPOSED TO AN INNOVATIVE CONFLICT

    OpenAIRE

    Chulkov Vitaliy Olegovich; Rakhmonov Emomali Karimovich; Kas'yanov Vitaliy Fedorovich; Gusakova Elena Aleksandrovna

    2012-01-01

    This article deals with the infographic modeling of hierarchical management systems exposed to innovative conflicts. The authors analyze the facts that serve as conflict drivers in the construction management environment. The reasons for innovative conflicts include changes in hierarchical structures of management systems, adjustment of workers to new management conditions, changes in the ideology, etc. Conflicts under consideration may involve contradictions between requests placed by custom...

  20. Improved Bio-inspired Artificial Gecko Adhesive by Using Hierarchical Fibrillar Structures

    OpenAIRE

    Li, Yasong

    2014-01-01

    Geckos are well known for being rapid climbers that have long existed in nature. The reversible and reusable adhesive on their feet intrigues scientists to explore a bio-mimetic adhesive, which inherits the adhesion properties of the gecko’s adhesives. Recent advances in electron microscopy reveal the secret of gecko’s climbing ability: there are hierarchical fibrillar structures branching from the skin of their climbing feet. Sizes of these hierarchical fibrils range from micrometer to nanom...

  1. A novel method for a multi-level hierarchical composite with brick-and-mortar structure.

    Science.gov (United States)

    Brandt, Kristina; Wolff, Michael F H; Salikov, Vitalij; Heinrich, Stefan; Schneider, Gerold A

    2013-01-01

    The fascination for hierarchically structured hard tissues such as enamel or nacre arises from their unique structure-properties-relationship. During the last decades this numerously motivated the synthesis of composites, mimicking the brick-and-mortar structure of nacre. However, there is still a lack in synthetic engineering materials displaying a true hierarchical structure. Here, we present a novel multi-step processing route for anisotropic 2-level hierarchical composites by combining different coating techniques on different length scales. It comprises polymer-encapsulated ceramic particles as building blocks for the first level, followed by spouted bed spray granulation for a second level, and finally directional hot pressing to anisotropically consolidate the composite. The microstructure achieved reveals a brick-and-mortar hierarchical structure with distinct, however not yet optimized mechanical properties on each level. It opens up a completely new processing route for the synthesis of multi-level hierarchically structured composites, giving prospects to multi-functional structure-properties relationships.

  2. Organizational and Spatial Dynamics of Attentional Focusing in Hierarchically Structured Objects

    Science.gov (United States)

    Yeari, Menahem; Goldsmith, Morris

    2011-01-01

    Is the focusing of visual attention object-based, space-based, both, or neither? Attentional focusing latencies in hierarchically structured compound-letter objects were examined, orthogonally manipulating global size (larger vs. smaller) and organizational complexity (two-level structure vs. three-level structure). In a dynamic focusing task,…

  3. Obstacle Avoidance of a Mobile Robot with Hierarchical Structure

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Gyu [Yeungnam College of Science and Technolgy, Taegu (Korea)

    2001-06-01

    This paper proposed a new hierarchical fuzzy-neural network algorithm for navigation of a mobile robot within unknown dynamic environment. Proposed navigation algorithm used the learning ability of the neural network and the feasibility of control highly nonlinear system of fuzzy theory. The proposed navigation algorithm used fuzzy algorithm for goal approach and fuzzy-network for effective collision avoidance. Some computer simulation results for a mobile robot equipped with ultrasonic range sensors show that the suggested navigation algorithm is very effective to escape in stationary and moving obstacles environment. (author). 11 refs., 14 figs., 2 tabs.

  4. Feasibility study on strengthening heating effect of high power short pulse laser on biological tissue by micro/nano metal particles

    Science.gov (United States)

    Lv, Yonggang; Huai, Xiulan

    2008-10-01

    A new method for enhancing the heating effect of high power short pulse laser on biological tissue by micro/nano metal particles was proposed. Theoretical analysis of the influences of the micro/nano particle kind, the concentration and the microcosmic distribution of micro/nano particles on the temperature response was carried out with a multi-layer hyperbolic heat conduction model with volumetric heat generation. The results indicate that embedding micro/nano particles could improve the surface temperature increase of biological tissue with short duration and reduce the deeper material temperature under the same heating condition, which would help strengthen the heating effects of high power short pulse laser on biological tissue. This study may open a new technical approach for improving laser applications.

  5. Origin of Hierarchical Structures of Quark and Lepton Mass Matrices

    CERN Document Server

    Koide, Yoshio

    2015-01-01

    It is shown that the so-called "Yukawaon" model can give a unified description of masses, mixing and $CP$ violation parameters of quarks and leptons without using any hierarchical (family number-dependent) parameters besides the charged lepton masses. Here, we have introduced a phase matrix $P={\\rm daig}(e^{i \\phi_1}, e^{i \\phi_2}, e^{i \\phi_3})$ with the phase parameters $(\\phi_1, \\phi_2, \\phi_3)$ which are described in terms of family number-independent parameters, together with using only the charged lepton mass parameters as the family number-dependent parameters. In this paper, the $CP$ violating phase parameters $\\delta_{CP}^q$ and $\\delta_{CP}^\\ell$ in the standard expression of $V_{CKM}$ and $U_{PMNS}$ are predicted as $\\delta_{CP}^q \\simeq 72^\\circ$ and $\\delta_{CP}^\\ell \\simeq -76^\\circ$, respectively, i.e. $\\delta_{CP}^\\ell \\sim - \\delta_{CP}^q$.

  6. Children's Knowledge of Hierarchical Phrase Structure: Quantifier Floating in Japanese

    Science.gov (United States)

    Suzuki, Takaaki; Yoshinaga, Naoko

    2013-01-01

    The interpretation of floating quantifiers in Japanese requires knowledge of hierarchical phrase structure. However, the input to children is insufficient or even misleading, as our analysis indicates. This presents an intriguing question on learnability: do children interpret floating quantifiers based on a structure-dependent rule which is not…

  7. Examining the Factor Structure and Hierarchical Nature of the Quality of Life Construct

    Science.gov (United States)

    Wang, Mian; Schalock, Robert L.; Verdugo, Miguel A.; Jenaro, Christina

    2010-01-01

    There is considerable debate in the area of individual quality of life research regarding the factor structure and hierarchical nature of the quality of life construct. Our purpose in this study was to test via structural equation modeling an a priori quality of life model consisting of eight first-order factors and one second-order factor. Data…

  8. A Hierarchical Linear Model with Factor Analysis Structure at Level 2

    Science.gov (United States)

    Miyazaki, Yasuo; Frank, Kenneth A.

    2006-01-01

    In this article the authors develop a model that employs a factor analysis structure at Level 2 of a two-level hierarchical linear model (HLM). The model (HLM2F) imposes a structure on a deficient rank Level 2 covariance matrix [tau], and facilitates estimation of a relatively large [tau] matrix. Maximum likelihood estimators are derived via the…

  9. Hierarchical Structure, Disassortativity and Information Measures of the US Flight Network

    Institute of Scientific and Technical Information of China (English)

    WANG Ru; CAI Xu

    2005-01-01

    @@ We investigate the mixing structure of directed and evolutionary US flight network. It is shown that such a network is a hierarchical network, with average assortativity coefficient -0.37. Application of the informationbased method that can give the same result provides a way to explore the structure of complex networks.

  10. Asymmetric block copolymer membranes with ultrahigh porosity and hierarchical pore structure by plain solvent evaporation

    KAUST Repository

    Yu, H.

    2016-09-14

    Membranes with a hierarchical porous structure could be manufactured from a block copolymer blend by pure solvent evaporation. Uniform pores in a 30 nm thin skin layer supported by a macroporous structure were formed. This new process is attractive for membrane production because of its simplicity and the lack of liquid waste.

  11. Hierarchical structure graphitic-like/MoS2 film as superlubricity material

    Science.gov (United States)

    Gong, Zhenbin; Jia, Xiaolong; Ma, Wei; Zhang, Bin; Zhang, Junyan

    2017-08-01

    Friction and wear result in a great amount of energy loss and the invalidation of mechanical parts, thus it is necessary to minimize friction in practical application. In this study, the graphitic-like/MoS2 films with hierarchical structure were synthesized by the combination of pulse current plasma chemical-vapor deposition and medium frequency unbalanced magnetron sputtering in preheated environment. This hierarchical structure composite with multilayer nano sheets endows the films excellent tribological performance, which easily achieves macro superlubricity (friction coefficient ∼0.004) under humid air. Furthermore, it is expected that hierarchical structure of graphitic-like/MoS2 films could match the requirements of large scale, high bear-capacity and wear-resistance of actual working conditions, which could be widely used in the industrial production as a promising superlubricity material.

  12. Hierarchical structure for audio-video based semantic classification of sports video sequences

    Science.gov (United States)

    Kolekar, M. H.; Sengupta, S.

    2005-07-01

    A hierarchical structure for sports event classification based on audio and video content analysis is proposed in this paper. Compared to the event classifications in other games, those of cricket are very challenging and yet unexplored. We have successfully solved cricket video classification problem using a six level hierarchical structure. The first level performs event detection based on audio energy and Zero Crossing Rate (ZCR) of short-time audio signal. In the subsequent levels, we classify the events based on video features using a Hidden Markov Model implemented through Dynamic Programming (HMM-DP) using color or motion as a likelihood function. For some of the game-specific decisions, a rule-based classification is also performed. Our proposed hierarchical structure can easily be applied to any other sports. Our results are very promising and we have moved a step forward towards addressing semantic classification problems in general.

  13. Leading virtual teams: hierarchical leadership, structural supports, and shared team leadership.

    Science.gov (United States)

    Hoch, Julia E; Kozlowski, Steve W J

    2014-05-01

    Using a field sample of 101 virtual teams, this research empirically evaluates the impact of traditional hierarchical leadership, structural supports, and shared team leadership on team performance. Building on Bell and Kozlowski's (2002) work, we expected structural supports and shared team leadership to be more, and hierarchical leadership to be less, strongly related to team performance when teams were more virtual in nature. As predicted, results from moderation analyses indicated that the extent to which teams were more virtual attenuated relations between hierarchical leadership and team performance but strengthened relations for structural supports and team performance. However, shared team leadership was significantly related to team performance regardless of the degree of virtuality. Results are discussed in terms of needed research extensions for understanding leadership processes in virtual teams and practical implications for leading virtual teams.

  14. Rapid prototyping of microfluidic devices with integrated wrinkled gold micro-/nano textured electrodes for electrochemical analysis.

    Science.gov (United States)

    Gabardo, C M; Adams-McGavin, R C; Vanderfleet, O M; Soleymani, L

    2015-08-21

    Fully-integrated electro-fluidic systems with micro-/nano-scale features have a wide range of applications in lab-on-a-chip systems used for biosensing, biological sample processing, and environmental monitoring. Rapid prototyping of application-specific electro-fluidic systems is envisioned to facilitate the testing, validation, and market translation of several lab-on-a-chip systems. Towards this goal, we developed a rapid prototyping process for creating wrinkled micro-/nano-textured electrodes on shrink memory polymers, fabricating microfluidics using molds patterned by a craft-cutter, and bonding electrical and fluidic circuitries using a PDMS partial curing method optimized for creating void-free bonds at the side walls and surfaces of tall (>5 μm) micro-/nano-textured wrinkled electrodes. The resulting electro-fluidic devices, featuring closely spaced high topography electrodes for electrochemical analysis, can withstand flow-rates and burst pressures larger than 25 mL min(-1) and 125 kPa, respectively. In addition, the fully-integrated electrochemical flow-cell developed here demonstrates excellent electrochemical behaviour, with negligible scan to scan variation for over 100 cyclic voltammetry scans, and expected redox signatures measured under various voltage scan rates and fluidic flow rates.

  15. Detecting Both the Mass and Position of an Accreted Particle by a Micro/Nano-Mechanical Resonator Sensor

    Directory of Open Access Journals (Sweden)

    Yin Zhang

    2014-09-01

    Full Text Available In the application of a micro-/nano-mechanical resonator, the position of an accreted particle and the resonant frequencies are measured by two different physical systems. Detecting the particle position sometimes can be extremely difficult or even impossible, especially when the particle is as small as an atom or a molecule. Using the resonant frequencies to determine the mass and position of an accreted particle formulates an inverse problem. The Dirac delta function and Galerkin method are used to model and formulate an eigenvalue problem of a beam with an accreted particle. An approximate method is proposed by ignoring the off-diagonal elements of the eigenvalue matrix. Based on the approximate method, the mass and position of an accreted particle can be decoupled and uniquely determined by measuring at most three resonant frequencies. The approximate method is demonstrated to be very accurate when the particle mass is small, which is the application scenario for much of the mass sensing of micro-/nano-mechanical  resonators. By solving the inverse problem,  the position measurement becomes unnecessary, which is of some help to the mass sensing application  of a micro-/nano-mechanical resonator by reducing two measurement systems to one. How to apply the method to the general scenario of multiple accreted particles is also discussed.

  16. Detecting both the mass and position of an accreted particle by a micro/nano-mechanical resonator sensor.

    Science.gov (United States)

    Zhang, Yin; Liu, Yun

    2014-09-02

    In the application of a micro-/nano-mechanical resonator, the position of an accreted particle and the resonant frequencies are measured by two different physical systems. Detecting the particle position sometimes can be extremely difficult or even impossible, especially when the particle is as small as an atom or a molecule. Using the resonant frequencies to determine the mass and position of an accreted particle formulates an inverse problem. The Dirac delta function and Galerkin method are used to model and formulate an eigenvalue problem of a beam with an accreted particle. An approximate method is proposed by ignoring the off-diagonal elements of the eigenvalue matrix. Based on the approximate method, the mass and position of an accreted particle can be decoupled and uniquely determined by measuring at most three resonant frequencies. The approximate method is demonstrated to be very accurate when the particle mass is small, which is the application scenario for much of the mass sensing of micro-/nano-mechanical  resonators. By solving the inverse problem,  the position measurement becomes unnecessary, which is of some help to the mass sensing application  of a micro-/nano-mechanical resonator by reducing two measurement systems to one. How to apply the method to the general scenario of multiple accreted particles is also discussed.

  17. The performances of silicon solar cell with core-shell p-n junctions of micro-nano pillars fabricated by cesium chloride self-assembly and dry etching

    Science.gov (United States)

    Liu, Jing; Zhang, Xinshuai; Dong, Gangqiang; Liao, Yuanxun; Wang, Bo; Zhang, Tianchong; Yi, Futing

    2014-03-01

    Silicon micro-nano pillars are cost-efficiently integrated using twice cesium chloride (CsCl) islands lithography technique and dry etching for solar cell applications. The micro PMMA islands are fabricated by inductively coupled plasma (ICP) dry etching with micro CsCl islands as masks, and the nano CsCl islands with nano sizes then are made on the surface of micro PMMA islands and silicon. By ICP dry etching with the mask of micro PMMA islands and nano CsCl islands, the micro-nano silicon pillars are made and certain height micro pillars are randomly positioned between dense arrays of nano pillars with different morphologies by controlling etching conditions. With 300 nm depth p-n junction detected by secondary-ion mass spectrometry (SIMS), the micro pillars of the diameter about 1 μm form the core-shell p-n junction to maximize utility of p-n junction interface and enable efficient free carrier collection, and the nano tapered pillars of 150 nm diameter are used to decrease reflection by a graded-refractive-index. Compared to single micro or nano pillar arrayed cells, the co-integrated solar cell with micro and nano pillars demonstrates improved photovoltaic characteristic that is a photovoltaic conversion efficiency (PCE) of 15.35 % with a short circuit current density ( J sc) of 38.40 mA/cm2 and an open circuit voltage ( V oc) of 555.7 mV, which benefits from the advantages of micro-nano pillar structures and can be further improved upon process optimization.

  18. Properties of micro-nano particle size admixtures of alumina at different sintering condition

    Science.gov (United States)

    Sifat, Rahin; Akter, Manira; Rashid, A. K. M. Bazlur

    2016-07-01

    Among various ceramic materials, alumina is mostly used material for its hardness and strength. There is a difference between the properties of alumina due to their different particle size. Also different holding time in the sintering temperature has effect on the sintering of alumina of different particle size. In this study, micro alumina and nano alumina were mixed in different ratios and sintered at different sintering condition to compare their mechanical properties that varied due to their different particle size distribution. In this work, conventional solid state sintering route was followed to prepare final samples. Six different particle size ratio of alumina (micro:nano= 100:0, 95:5, 90:10, 10:90, 5:95, 0:100) with a doping of 0.1% MgO were used. The sintering temperature was 1500° C but sintering condition was different. After comparing the mechanical properties, it has been observed that relatively improved properties can be obtained by increasing nano particle percentages in the micro alumina than the reverse mixture.

  19. Micro/nano engineering on stainless steel substrates to produce superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Beckford, Samuel; Zou Min, E-mail: mzou@uark.edu

    2011-12-30

    Creating micro-/nano-scale topography on material surfaces to change their wetting properties has been a subject of much interest in recent years. Wenzel in 1936 and Cassie and Baxter in 1944 proposed that by microscopically increasing the surface roughness of a substrate, it is possible to increase its hydrophobicity. This paper reports the fabrication of micro-textured surfaces and nano-textured surfaces, and the combination of both on stainless steel substrates by sandblasting, thermal evaporation of aluminum, and aluminum-induced crystallization (AIC) of amorphous silicon (a-Si). Meanwhile, fluorinated carbon films were used to change the chemical composition of the surfaces to render the surfaces more hydrophobic. These surface modifications were investigated to create superhydrophobic surfaces on stainless steel substrates. The topography resulting from these surface modifications was analyzed by scanning electron microscopy and surface profilometry. The wetting properties of these surfaces were characterized by water contact angle measurement. The results of this study show that superhydrophobic surfaces can be produced by either micro-scale surface texturing or nano-scale surface texturing, or the combination of both, after fluorinated carbon film deposition.

  20. Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

    Science.gov (United States)

    Mackinson, B. L.; Moran, S. B.; Lomas, M. W.; Stewart, G. M.; Kelly, R. P.

    2015-06-01

    The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th-238U disequilibria and, during two cruises, measured by a sediment trap at Ocean Station Papa. POC fluxes at 100 m ranged from 0.65 to 7.95 mmol m-2 d-1, similar in magnitude to previous results at Line P. Microplankton pigments dominate indicator pigment fluxes (averaging 69 ± 19% of total pigment flux), while nanoplankton pigments comprised the majority of pigment standing stocks (averaging 64 ± 23% of total pigment standing stocks). Indicator pigment loss rates (the ratio of pigment export flux to pigment standing stocks) point to preferential export of larger microplankton relative to smaller nano- and picoplankton. However, indicator pigments do not quantitatively trace particle export resulting from zooplankton grazing, which may be an important pathway for the export of small phytoplankton. These results have important implications for understanding the magnitude and mechanisms controlling the biological pump at Line P in particular, and more generally in oligotrophic gyres and high-nutrient, low-chlorophyll (HNLC) regions where small phytoplankton represent a major component of the autotrophic community.

  1. Micro-Nano Materials for Tumor Microwave Hyperthermia: Design, Preparation, and Application.

    Science.gov (United States)

    Chen, Xue; Meng, Xianwei; Tan, Longfei; Liu, Tianlong

    2016-01-07

    Nowadays, cancer hyperthermia is attracting much attention in basic science and clinics. Among the hyperthermia techniques, microwave (MW) heating is most commonly used for cancer treatment. It offers highly competitive advantages: faster heat generation from microwave radiation, less susceptibility to heat up local tissues, maneuverability, and depth of penetration in tissues and capability of killing tumor cells. Although the encouraging clinical results are being collected, MW hyperthermia has its own challenges, such as inaccurate targeting, low selectivity, which leads to damage to surrounding vital organs and tissues. To address these issues, micro-nano materials have emerged as a promising agent as the receiver of the electromagnetic wave, which should be beneficial for improving the efficacy of MW hyperthermia. Here, we review the most recent literature on micro/nanomaterials-based MW heating strategies for treatment of cancer, with the aim to give the reader an overview of the state-of-the-art of MW hyperthermia therapy. The future of MW responsive materials will also be discussed, including combination of imaging probes and targeting moieties.

  2. A novel bioinspired PVDF micro/nano hair receptor for a robot sensing system.

    Science.gov (United States)

    Li, Fei; Liu, Weiting; Stefanini, Cesare; Fu, Xin; Dario, Paolo

    2010-01-01

    This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride) fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots.

  3. A Novel Bioinspired PVDF Micro/Nano Hair Receptor for a Robot Sensing System

    Directory of Open Access Journals (Sweden)

    Xin Fu

    2010-01-01

    Full Text Available This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots.

  4. Subsurface Transport Behavior of Micro-Nano Bubbles and Potential Applications for Groundwater Remediation

    Directory of Open Access Journals (Sweden)

    Hengzhen Li

    2013-12-01

    Full Text Available Micro-nano bubbles (MNBs are tiny bubbles with diameters on the order of micrometers and nanometers, showing great potential in environmental remediation. However, the application is only in the beginning stages and remains to be intensively studied. In order to explore the possible use of MNBs in groundwater contaminant removal, this study focuses on the transport of MNBs in porous media and dissolution processes. The bubble diameter distribution was obtained under different conditions by a laser particle analyzer. The permeability of MNB water through sand was compared with that of air-free water. Moreover, the mass transfer features of dissolved oxygen in water with MNBs were studied. The results show that the bubble diameter distribution is influenced by the surfactant concentration in the water. The existence of MNBs in pore water has no impact on the hydraulic conductivity of sand. Furthermore, the dissolved oxygen (DO in water is greatly increased by the MNBs, which will predictably improve the aerobic bioremediation of groundwater. The results are meaningful and instructive in the further study of MNB research and applications in groundwater bioremediation.

  5. Slip of polymer melts over micro/nano-patterned metallic surfaces.

    Science.gov (United States)

    Ebrahimi, Marzieh; Konaganti, Vinod Kumar; Moradi, Sona; Doufas, Antonios K; Hatzikiriakos, Savvas G

    2016-12-06

    The slip behavior of high-density polyethylenes (HDPEs) is studied over surfaces of different topology and surface energy. Laser ablation has been used to micro/nano-pattern the surface of dies in order to examine the effect of surface roughness on slip. In addition, fluoroalkyl silane-based coatings on smooth and patterned substrates were used to understand the effect of surface energy on slip. Surface roughness and surface energy effects were incorporated into the double reptation slip model (Ebrahimi et al., J. Rheol., 2015, 59, 885-901) in order to predict the slip velocity of studied polymers on different substrates. It was found that for dies with rough surfaces, polymer melt penetrates into the cavities of the substrate (depending on the depth and the distance between the asperities), thus decreasing wall slip. On the other hand, silanization of the surface increases the slip velocity of polymers in the case of smooth die, although it has a negligible effect on rough dies. Interestingly, the slip velocity of the studied polymers on various substrates of different degrees of roughness and surface energy, were brought into a mastercurve by modifying the double reptation slip velocity model.

  6. Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes.

    Science.gov (United States)

    Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

    2017-05-23

    This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

  7. Controlling cell adhesion via replication of laser micro/nano-textured surfaces on polymers

    Energy Technology Data Exchange (ETDEWEB)

    Koufaki, Niki; Ranella, Anthi; Barberoglou, Marios; Psycharakis, Stylianos; Fotakis, Costas; Stratakis, Emmanuel [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), 711 10, Heraklion, Crete (Greece); Aifantis, Katerina E, E-mail: stratak@iesl.forth.gr [Lab of Mechanics and Materials, Aristotle University of Thessaloniki, Thessaloniki (Greece)

    2011-12-15

    The aim of this study is to investigate cell adhesion and viability on highly rough polymeric surfaces with gradient roughness ratios and wettabilities prepared by microreplication of laser micro/nano-textured Si surfaces. Negative replicas on polydimethylsiloxane as well as positive ones on a photocurable (organically modified ceramic) and a biodegradable (poly(lactide-co-glycolide)) polymer have been successfully reproduced. The final culture substrates comprised from forests of micron-sized conical spikes exhibiting a range of roughness ratios and wettabilities, was achieved by changing the laser fluence used to fabricate the original template surfaces. Cell culture experiments were performed with the fibroblast NIH/3T3 and PC12 neuronal cell lines in order to investigate how these surfaces are capable of modulating different types of cellular responses including, viability, adhesion and morphology. The results showed a preferential adhesion of both cell types on the microstructured surfaces compared to the unstructured ones. In particular, the fibroblast NIH/3T3 cells show optimal adhesion for small roughness ratios, independent of the surface wettability and polymer type, indicating a non-monotonic dependence of cell adhesion on surface energy. In contrast, the PC12 cells were observed to adhere well to the patterned surfaces independent of the roughness ratio and wettability. These experimental findings are correlated with micromechanical measurements performed on the unstructured and replicated surfaces and discussed on the basis of previous observations describing the relation of cell response to surface energy and rigidity.

  8. A Micro/Nano Composite for Combination Treatment of Melanoma Lung Metastasis.

    Science.gov (United States)

    Mi, Yu; Mu, Chaofeng; Wolfram, Joy; Deng, Zaian; Hu, Tony Ye; Liu, Xuewu; Blanco, Elvin; Shen, Haifa; Ferrari, Mauro

    2016-04-20

    The successful treatment of malignant disease generally requires the use of multiple therapeutic agents that are coordinated in a spatiotemporal manner to enable synergy. Here, a porous silicon-based micro/nano composite (MNC) that is capable of simultaneously delivering chemotherapeutic agents and small interfering RNA (siRNA) to the lungs following intravenous injection is designed. The pores of the silicon microparticles are loaded with B-Raf proto-oncogene serine/threonine kinase (BRAF) siRNA-containing liposomes, while the surface is conjugated with docetaxel-encapsulated polymeric nanoparticles. The synergistic antitumor effect of the MNC is demonstrated in vitro in melanoma cells and in vivo using a mouse model for melanoma lung metastasis. The MNC displays superior therapeutic efficacy and increased accumulation in metastatic melanoma lesions in the lungs in comparison to combination therapy with liposomes and polymers. The results indicate that the MNC can be used as an effective delivery vehicle for simultaneous enrichment of multiple therapeutic agents in the lungs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Influence of structured sidewalls on the wetting states and superhydrophobic stability of surfaces with dual-scale roughness

    Science.gov (United States)

    Wu, Huaping; Zhu, Kai; Wu, Bingbing; Lou, Jia; Zhang, Zheng; Chai, Guozhong

    2016-09-01

    The superhydrophobicity of biological surfaces with dual-scale roughness has recently received considerable attention because of the unique wettability of such surfaces. Based on this, artificial micro/nano hierarchical structures with structured sidewalls and smooth sidewalls were designed and the influences of sidewall configurations (i.e., structured and smooth) on the wetting state of micro/nano hierarchical structures were systematically investigated based on thermodynamics and the principle of minimum free energy. Wetting transition and superhydrophobic stability were then analyzed for a droplet on dual-scale rough surfaces with structured and smooth sidewalls. Theoretical analysis results show that dual-scale rough surfaces with structured sidewalls have a larger "stable superhydrophobic region" than those with smooth sidewalls. The dual-scale rough surfaces with smooth sidewalls can enlarge the apparent contact angle (ACA) without improvement in the superhydrophobic stability. By contrast, dual-scale rough surfaces with structured sidewalls present an advantage over those with smooth sidewalls in terms of enlarging ACA and enhancing superhydrophobic stability. The proposed thermodynamic model is valid when compared with previous experimental data and numerical analysis results, which is helpful for designing and understanding the wetting states and superhydrophobic stability of surfaces with dual-scale roughness.

  10. Hierarchical Self-Assembled Structures from POSS-Containing Block Copolymers Synthesized by Living Anionic Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Tomoyasu; Leolukman, Melvina; Jin, Sangwoo; Goseki, Raita; Ishida, Yoshihito; Kakimoto, Masa-aki; Hayakawa, Teruaki; Ree, Moonhor; Gopalan, Padma; (Tokyo Inst. Tech.); (UW); (POSTECH)

    2010-03-16

    Two kinds of polyhedral oligomeric silsesquioxane (POSS)-containing block copolymers (BCPs), namely PS-b-PMAPOSS and PMMA-b-PMAPOSS, were synthesized by living anionic polymerization. A wide range of molecular weights were obtained with a very narrow polydispersity index of less than 1.09. The bulk samples prepared by slow evaporation from a polymer solution in chloroform exhibit well-defined microphase-separated structures with long-range order. Thermal annealing induced hierarchical structures consisting of a smaller length scale ordered crystalline POSS domains within the larger microphase-separated structures. We report detailed structural characterization of these hierarchical structures in bulk and thin films by transmission electron microscopy and grazing incidence wide-angle X-ray scattering (GIWAXS). On the basis of this structural analysis, we propose a model for the formation of an orthorhombic lattice structure through the aggregation of POSS segments which formed a helix-like structure.

  11. Construction of super-hydrophobic iron with a hierarchical surface structure

    Science.gov (United States)

    Yuan, Zhiqing; Bin, Jiping; Wang, Xian; Wang, Menglei; Peng, Chaoyi; Xing, Suli; Xiao, Jiayu; Zeng, Jingcheng; Xiao, Ximei; Fu, Xin

    2014-04-01

    Wettability of an iron surface is crucial for the wide applications of iron in practice. In this work, a hierarchical structure highly similar to that of the underside of a bamboo leaf was constructed on an iron surface via the template method and controllable etching. After modification by stearic acid, the iron surface with hierarchical structure showed excellent water repellency, with an average contact angle of 156° and a sliding angle of 3°. X-ray diffraction (XRD) techniques and Fourier transform infrared spectroscopy (FTIR) are applied to examine the chemical components of an iron surface.

  12. Multi-scaling hierarchical structure analysis on the sequence of E. coli complete genome

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We have applied the newly developed hierarchical structure theory for complex systems to analyze the multi-scaling structures of the nucleotide density distribution along a linear DNA sequence from the complete Escherichia coli genome. The hierarchical symmetry in the nucleotide density distribution was demonstrated. In particular, we have shown that the G, C density distribution that represents a strong H-bonding between the two DNA chains is more coherent with smaller similarity parameter compared to that of A, T density distribution, indicating a better organized multi-scaling fluctuation field for G, C density distribution along the genome sequence. The biological significance of these findings is under investigation.

  13. A spatial analysis of hierarchical waste transport structures under growing demand.

    Science.gov (United States)

    Tanguy, Audrey; Glaus, Mathias; Laforest, Valérie; Villot, Jonathan; Hausler, Robert

    2016-10-01

    The design of waste management systems rarely accounts for the spatio-temporal evolution of the demand. However, recent studies suggest that this evolution affects the planning of waste management activities like the choice and location of treatment facilities. As a result, the transport structure could also be affected by these changes. The objective of this paper is to study the influence of the spatio-temporal evolution of the demand on the strategic planning of a waste transport structure. More particularly this study aims at evaluating the effect of varying spatial parameters on the economic performance of hierarchical structures (with one transfer station). To this end, three consecutive generations of three different spatial distributions were tested for hierarchical and non-hierarchical transport structures based on costs minimization. Results showed that a hierarchical structure is economically viable for large and clustered spatial distributions. The distance parameter was decisive but the loading ratio of trucks and the formation of clusters of sources also impacted the attractiveness of the transfer station. Thus the territories' morphology should influence strategies as regards to the installation of transfer stations. The use of spatial-explicit tools such as the transport model presented in this work that take into account the territory's evolution are needed to help waste managers in the strategic planning of waste transport structures.

  14. Controlled Fabrication of Flower-like Nickel Oxide Hierarchical Structures and Their Application in Water Treatment

    Directory of Open Access Journals (Sweden)

    Linxia Wang

    2012-01-01

    Full Text Available Flower-like NiO hierarchical structures with 2–5 μm diameter assembled from nanosheet building blocks have been successfully fabricated via a wet-chemical method combined with thermodecomposition technology. The template-free method is facile and effective in preparing flower-like NiO superstructures in high yield. The intermediate product and final hierarchical structures are characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray diffraction (XRD, Fourier transform IR (FTIR, and thermogravimetric analysis (TGA. The effects of growth temperature and reaction time on the morphologies of the as-prepared structures were investigated by SEM characterization and a possible mechanism for the formation of flower-like NiO is proposed. Based on the nitrogen adsorption and desorption measurements, the BET surface area of the as-obtained sample is 55.7 m2/g and the pore-size distribution plot indicates a bimodal mesopore distribution, with pore sizes of ca. 2.6 nm and 7.4 nm, respectively. In comparison with sphere-like and rod-like structures, the flower-like NiO hierarchical structures show an excellent ability to rapidly remove various pollutants when used as adsorbent and photocatalyst in waste-water treatment, which may be attributed to its unique hierarchical and porous surface structures.

  15. Joint Hierarchical Category Structure Learning and Large-Scale Image Classification

    Science.gov (United States)

    Qu, Yanyun; Lin, Li; Shen, Fumin; Lu, Chang; Wu, Yang; Xie, Yuan; Tao, Dacheng

    2017-09-01

    We investigate the scalable image classification problem with a large number of categories. Hierarchical visual data structures are helpful for improving the efficiency and performance of large-scale multi-class classification. We propose a novel image classification method based on learning hierarchical inter-class structures. Specifically, we first design a fast algorithm to compute the similarity metric between categories, based on which a visual tree is constructed by hierarchical spectral clustering. Using the learned visual tree, a test sample label is efficiently predicted by searching for the best path over the entire tree. The proposed method is extensively evaluated on the ILSVRC2010 and Caltech 256 benchmark datasets. Experimental results show that our method obtains significantly better category hierarchies than other state-of-the-art visual tree-based methods and, therefore, much more accurate classification.

  16. Topology of the correlation networks among major currencies using hierarchical structure methods

    Science.gov (United States)

    Keskin, Mustafa; Deviren, Bayram; Kocakaplan, Yusuf

    2011-02-01

    We studied the topology of correlation networks among 34 major currencies using the concept of a minimal spanning tree and hierarchical tree for the full years of 2007-2008 when major economic turbulence occurred. We used the USD (US Dollar) and the TL (Turkish Lira) as numeraires in which the USD was the major currency and the TL was the minor currency. We derived a hierarchical organization and constructed minimal spanning trees (MSTs) and hierarchical trees (HTs) for the full years of 2007, 2008 and for the 2007-2008 period. We performed a technique to associate a value of reliability to the links of MSTs and HTs by using bootstrap replicas of data. We also used the average linkage cluster analysis for obtaining the hierarchical trees in the case of the TL as the numeraire. These trees are useful tools for understanding and detecting the global structure, taxonomy and hierarchy in financial data. We illustrated how the minimal spanning trees and their related hierarchical trees developed over a period of time. From these trees we identified different clusters of currencies according to their proximity and economic ties. The clustered structure of the currencies and the key currency in each cluster were obtained and we found that the clusters matched nicely with the geographical regions of corresponding countries in the world such as Asia or Europe. As expected the key currencies were generally those showing major economic activity.

  17. Hybrid nanostructured thin-films by PLD for enhanced field emission performance for radiation micro-nano dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, E., E-mail: maniphysics@gmail.com [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); Materials Science Group (MSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Sree Balaji Medical College & Hospital (SBMCH), Bharath University, Chrompet, Chennai 600044 (India); Kennedy, J. [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Kavitha, G. [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); PG& Research Dept of Physics, AM Jain College Affiliated to University of Madras, Chennai 600114 (India); and others

    2015-10-25

    We report the observation of hybrid nanostructured thin-films such as diamond-like carbon (DLC) signature on the ZnO epitaxial thin-films grown onto the device silicon/quartz substrate by reactive pulsed laser deposition (r-PLD) under the argon–oxygen (Ar|O{sub 2}) ambient at 573 K. Undoped and Carbon (C) doped epitaxial ZnO thin-film layer formation is revealed by the accelerator based ion-beam analysis (IBA) technique of resonant Rutherford backscattering spectrometry (RRBS), glancing-incidence X-ray diffraction (GIXRD) pattern, micro-Raman spectroscopy (μ-RS) and field-emission (F-E) studies. The RRBS and GIXRD results show the deposition of epitaxial thin-films containing C into ZnO. The μ-RS technique is a standard nondestructive tool (NDT) for the characterization of crystalline, nano-crystalline, and amorphous carbons (a-C). As grown ZnO and C-doped ZnO thin-films μ-RS result reveal the doping effect of C-impurities that appear in the form of DLC evident from Raman peaks at 1357 and 1575 cm{sup −1} along with a wurtzite structure peak at 438 cm{sup −1} with E{sub 2}(h) phonon of ZnO. The electron transport F-E result shows the hybrid thin-films has high conductivity than the un-doped film. Fabricated hybrid nanostructured thin-films materials could be very useful for the emerging applications of micro-nano dosimetry. - Highlights: • Observation of hybrid nanostructured diamond-like carbon (DLC) on ZnO epitaxial thin-films at 573 K. • Carbon doped epitaxial ZnO thin-film layer formation is revealed by RRBS, Micro-Raman. • Field-emission (F-E) study. • DLC formation evident from Raman peaks at 1357 and 1575 cm{sup −1} along with a wurtzite structure peak of ZnO. • The electron transport F-E result shows the hybrid thin-film has high conductivity than the undoped thin-film.

  18. Hierarchically structured polysulfone/titania fibrous membranes with enhanced air filtration performance.

    Science.gov (United States)

    Wan, Huigao; Wang, Na; Yang, Jianmao; Si, Yinsong; Chen, Kun; Ding, Bin; Sun, Gang; El-Newehy, Mohamed; Al-Deyab, Salem S; Yu, Jianyong

    2014-03-01

    Hierarchically structured, superhydrophobic filter medium exhibiting robust filtration performance to airborne particulate were prepared by a facile deposition of electrospun polysulfone/titania nanoparticles (PSU/TiO2 NPs) on a conventional nonwoven substrate. The air permeability, tensile strength and abrasion resistance of pristine PSU fibrous membranes could be finely controlled by regulating the solvent composition and number ratios of jets. By employing the TiO2 NPs incorporation, the pristine PSU fibers were endowed with promising superhydrophobicity with a water contact angle of up to 152°. The quantitative hierarchical roughness analysis using N2 adsorption method has confirmed the major contribution of TiO2 NPs on enhancing the porous structure and surface fractal features with irregular rough structure. Filtration performance studies have revealed that the filtration efficiency and pressure drop of resultant hybrid membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Furthermore, the as-prepared PSU/TiO2-5 membrane exhibited improved filtration efficiency (99.997%) and pressure drop (45.3 Pa) compared with pristine PSU membrane, which would make them a promising media for fine particle filtration, and a new insight was also provided into the design and development of high performance filter medium based on hierarchical structured fibers.

  19. Hierarchically structured nanocarbon electrodes for flexible solid lithium batteries

    KAUST Repository

    Wei, Di

    2013-09-01

    The ever increasing demand for storage of electrical energy in portable electronic devices and electric vehicles is driving technological improvements in rechargeable batteries. Lithium (Li) batteries have many advantages over other rechargeable battery technologies, including high specific energy and energy density, operation over a wide range of temperatures (-40 to 70. °C) and a low self-discharge rate, which translates into a long shelf-life (~10 years) [1]. However, upon release of the first generation of rechargeable Li batteries, explosions related to the shorting of the circuit through Li dendrites bridging the anode and cathode were observed. As a result, Li metal batteries today are generally relegated to non-rechargeable primary battery applications, because the dendritic growth of Li is associated with the charging and discharging process. However, there still remain significant advantages in realizing rechargeable secondary batteries based on Li metal anodes because they possess superior electrical conductivity, higher specific energy and lower heat generation due to lower internal resistance. One of the most practical solutions is to use a solid polymer electrolyte to act as a physical barrier against dendrite growth. This may enable the use of Li metal once again in rechargeable secondary batteries [2]. Here we report a flexible and solid Li battery using a polymer electrolyte with a hierarchical and highly porous nanocarbon electrode comprising aligned multiwalled carbon nanotubes (CNTs) and carbon nanohorns (CNHs). Electrodes with high specific surface area are realized through the combination of CNHs with CNTs and provide a significant performance enhancement to the solid Li battery performance. © 2013 Elsevier Ltd.

  20. Hierarchical structures in cold-drawn pearlitic steel wire

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Godfrey, Andrew; Hansen, Niels

    2013-01-01

    in the structure and crystallography when a randomly oriented cementite structure in a patented wire during wire drawing is transformed into a lamellar structure parallel to the drawing axis. Changes in the interlamellar spacing and in the misorientation angle along and across the ferrite lamellae show significant...

  1. Hierarchical structural nanopore arrays fabricated by pre-patterning aluminum using nanosphere lithography.

    Science.gov (United States)

    Wang, Xinnan; Xu, Shuping; Cong, Ming; Li, Haibo; Gu, Yuejiao; Xu, Weiqing

    2012-04-10

    A highly ordered and hierarchical structural nanopore array is fabricated via anodizing a pre-patterned aluminum foil under an optimized voltage. A pre-patterned hexagonal nanoindentation array on an aluminum substrate is prepared via the nanosphere lithography method. This pattern leads to an elaborate nanochannel structure with seven nanopores in each nanoindentation after anodization treatment. The structure achieved in our study is new, interesting, and likely to be applied in photonic devices.

  2. Elaborately prepared hierarchical structure titanium dioxide for remarkable performance in lithium storage

    Science.gov (United States)

    Tian, Qinghua; Luo, Dong; Li, Xiaowei; Zhang, Zhengxi; Yang, Li; Hirano, Shin-ichi

    2016-05-01

    Titanium dioxide (TiO2) has been considered to be a promisingly alternative anode material for lithium-ion batteries and thus attracted wide research interest. But, its practical application in lithium-ion batteries is seriously impeded by low capacity and poor rate capability. In the present work, the electrochemical performance of TiO2 is significantly improved by elaborately fabricating hierarchical structures. These as-prepared four hierarchical structure TiO2 assembled by different building blocks (TO2-2 h, TO2-6 h, TO2-18 h and TO2-24 h) all exhibit impressed performance. More importantly, the TO2-6 h constructed by curved nanosheets exhibits the best performance, delivering a capacity of 231.6 mAh g-1 at 0.2C after 200 cycles, and capacities of 187.1 and 129.3 mAh g-1 at 1 and 10C after even 1200 cycles, respectively. The results indicated that design and fabrication of hierarchical structure is an effective strategy for significantly improving the electrochemical performance of TiO2 electrodes, and the electrochemical performance of hierarchical structure TiO2 is heavily dependent on its building blocks. It is suggested that thus excellent electrochemical performance may make TiO2-6 h a promising anode material for advanced lithium-ion batteries with high capacity, good rate capability and long life.

  3. Can Prosody Be Used to Discover Hierarchical Structure in Continuous Speech?

    Science.gov (United States)

    Langus, Alan; Marchetto, Erika; Bion, Ricardo Augusto Hoffmann; Nespor, Marina

    2012-01-01

    We tested whether adult listeners can simultaneously keep track of variations in pitch and syllable duration in order to segment continuous speech into phrases and group these phrases into sentences. The speech stream was constructed so that prosodic cues signaled hierarchical structures (i.e., phrases embedded within sentences) and non-adjacent…

  4. Symptom structure of PTSD: support for a hierarchical model separating core PTSD symptoms from dysphoria

    NARCIS (Netherlands)

    Rademaker, A.R.; Minnen, A. van; Ebberink, F.; Zuiden, M. van; Geuze, E.

    2012-01-01

    Background: As of yet, no collective agreement has been reached regarding the precise factor structure of posttraumatic stress disorder (PTSD). Several alternative factor-models have been proposed in the last decades. Objective: The current study examined the fit of a hierarchical adaptation of the

  5. A developmental model of hierarchical stage structure in objective moral judgements

    NARCIS (Netherlands)

    J. Boom; P.C.M. Molenaar

    1989-01-01

    A hierarchical structural model of moral judgment is proposed in which an S is characterized as occupying a particular moral stage. During development, the S's characteristic stage progresses along a latent, ordered dimension in an age-dependent way. Evaluation of prototypic statements representativ

  6. Task Switching in a Hierarchical Task Structure: Evidence for the Fragility of the Task Repetition Benefit

    Science.gov (United States)

    Lien, Mei-Ching; Ruthruff, Eric

    2004-01-01

    This study examined how task switching is affected by hierarchical task organization. Traditional task-switching studies, which use a constant temporal and spatial distance between each task element (defined as a stimulus requiring a response), promote a flat task structure. Using this approach, Experiment 1 revealed a large switch cost of 238 ms.…

  7. Hierarchical structures in cold-drawn pearlitic steel wire

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Godfrey, Andrew; Hansen, Niels

    2013-01-01

    The microstructure and crystallography of drawn pearlitic steel wires have been quantified by a number of electron microscopy techniques including scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction and nanobeam diffraction, with focus on the change......, and high-angle boundaries form in the A_BC structure parallel to the cementite lamellae. The structural and crystallographic analyses suggest that boundary strengthening and dislocation strengthening are important mechanisms in the cold-drawn wire. However, differences in structural parameters between...

  8. Mapping the hierarchical layout of the structural network of the macaque prefrontal cortex.

    Science.gov (United States)

    Goulas, Alexandros; Uylings, Harry B M; Stiers, Peter

    2014-05-01

    A consensus on the prefrontal cortex (PFC) holds that it is pivotal for flexible behavior and the integration of the cognitive, affective, and motivational domains. Certain models have been put forth and a dominant model postulates a hierarchical anterior-posterior gradient. The structural connectivity principles of this model dictate that increasingly anterior PFC regions exhibit more efferent connections toward posterior ones than vice versa. Such hierarchical asymmetry principles are thought to pertain to the macaque PFC. Additionally, the laminar patterns of the connectivity of PFC regions can be used for defining hierarchies. In the current study, we formally tested the asymmetry-based hierarchical principles of the anterior-posterior model by employing an exhaustive dataset on macaque PFC connectivity and tools from network science. On the one hand, the asymmetry-based principles and predictions of the hierarchical anterior-posterior model were not confirmed. The wiring of the macaque PFC does not fully correspond to the principles of the model, and its asymmetry-based hierarchical layout does not follow a strict anterior-posterior gradient. On the other hand, our results suggest that the laminar-based hierarchy seems a more tenable working hypothesis for models advocating an anterior-posterior gradient. Our results can inform models of the human PFC.

  9. Flexible supercapacitors with high areal capacitance based on hierarchical carbon tubular nanostructures

    Science.gov (United States)

    Zhang, Haitao; Su, Hai; Zhang, Lei; Zhang, Binbin; Chun, Fengjun; Chu, Xiang; He, Weidong; Yang, Weiqing

    2016-11-01

    Hierarchical structure design can greatly enhance the unique properties of primary material(s) but suffers from complicated preparation process and difficult self-assembly of materials with different dimensionalities. Here we report on the growth of single carbon tubular nanostructures with hierarchical structure (hCTNs) through a simple method based on direct conversion of carbon dioxide. Resorting to in-situ transformation and self-assembly of carbon micro/nano-structures, the obtained hCTNs are blood-like multichannel hierarchy composed of one large channel across the hCTNs and plenty of small branches connected to each other. Due to the unique pore structure and high surface area, these hCTN-based flexible supercapacitors possess the highest areal capacitance of ∼320 mF cm-2, as well as good rate-capability and excellent cycling stability (95% retention after 2500 cycles). It was established that this method can control the morphology, size, and density of hCTNs and effectively construct hCTNs well anchored to the various substrates. Our work unambiguously demonstrated the potential of hCTNs for large flexible supercapacitors and integrated energy management electronics.

  10. Mechanical, Biological and Electrochemical Investigations of Advanced Micro/Nano Materials for Tissue Engineering and Energy Storage

    Science.gov (United States)

    Pu, Juan

    Various micro/nano materials have been extensively studied for applications in tissue engineering and energy storage. Tissue engineering seeks to repair or replace damaged tissue by integrating approaches from cellular/molecular biology and material chemistry/engineering. A major challenge is the consistent design of three-dimensional (3D) scaffolds that mimic the structure and biological functions of extracellular matrix (ECM), guide cell migration, provide mechanical support, and regulate cell activity. Electrospun micro/nanofibers have been investigated as promising tissue engineering scaffolds because they resemble native ECM and possess tunable surface morphologies. Supercapacitors, one of the energy storage devices, bridge the performance gap between rechargeable batteries and conventional capacitors. Active electrode materials of supercapacitors must possess high specific surface area, high conductivity, and good electrochemical properties. Carbon-based micro/nano-particles, such as graphene, activated carbon (AC), and carbon nanotubes, are commonly used as active electrode materials for storing charge in supercapacitors by the electrical double layer mechanism due to their high specific surface area and excellent conductivity. In this thesis, the mechanical properties of electrospun bilayer microfibrous membranes were investigated for potential applications in tissue engineering. Bilayer microfibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning using a parallel-disk mandrel configuration, which resulted in the sequential deposition of a layer with aligned fibers (AFL) across the two parallel disks and a layer with random fibers (RFL), both deposited by a single process step. The membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, the bilayer membranes exhibited higher porosity than the

  11. Proton Conduction in Sulfonated Organic-Inorganic Hybrid Monoliths with Hierarchical Pore Structure.

    Science.gov (United States)

    von der Lehr, Martin; Seidler, Christopher F; Taffa, Dereje H; Wark, Michael; Smarsly, Bernd M; Marschall, Roland

    2016-09-28

    Porous organic-inorganic hybrid monoliths with hierarchical porosity exhibiting macro- and mesopores are prepared via sol-gel process under variation of the mesopore size. Organic moieties in the pore walls are incorporated by substituting up to 10% of the silicon precursor tetramethylorthosilicate with bisilylated benzene molecules. After functionalization with sulfonic acid groups, the resulting sulfonated hybrid monoliths featuring a bimodal pore structure are investigated regarding proton conduction depending on temperature and relative humidity. The hierarchical pore system and controlled mesopore design turn out to be crucial for sulfonation and proton conduction. These sulfonated hybrid hierarchical monoliths containing only 10% organic precursor exhibit higher proton conduction at different relative humidities than sulfonated periodic mesoporous organosilica made of 100% bisilylated precursors exhibiting solely mesopores, even with a lower concentration of sulfonic acid groups.

  12. Hierarchical cluster-tendency analysis of the group structure in the foreign exchange market

    Science.gov (United States)

    Wu, Xin-Ye; Zheng, Zhi-Gang

    2013-08-01

    A hierarchical cluster-tendency (HCT) method in analyzing the group structure of networks of the global foreign exchange (FX) market is proposed by combining the advantages of both the minimal spanning tree (MST) and the hierarchical tree (HT). Fifty currencies of the top 50 World GDP in 2010 according to World Bank's database are chosen as the underlying system. By using the HCT method, all nodes in the FX market network can be "colored" and distinguished. We reveal that the FX networks can be divided into two groups, i.e., the Asia-Pacific group and the Pan-European group. The results given by the hierarchical cluster-tendency method agree well with the formerly observed geographical aggregation behavior in the FX market. Moreover, an oil-resource aggregation phenomenon is discovered by using our method. We find that gold could be a better numeraire for the weekly-frequency FX data.

  13. Biomimetic hierarchical growth and self-assembly of hydroxyapatite/titania nanocomposite coatings and their biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Nathanael, A. Joseph, E-mail: ajosephnc@yahoo.com [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Im, Young Min [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Oh, Tae Hwan, E-mail: taehwanoh@ynu.ac.kr [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Yuvakkumar, R. [Department of Nanomaterials Engineering, Chungnam National University, Daejeon (Korea, Republic of); Mangalaraj, D. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore (India)

    2015-03-30

    Graphical abstract: - Highlights: • Novel ‘bowtie’ like biomimetic HA/TiO{sub 2} nanocomposite coatings were prepared. • Simple sol–gel method was used to achieve this novel structure. • Details analysis confirms the formation of bowtie like structure in many ways. • Their functional analysis showed their enhanced activity for biomedical application. - Abstract: This article describes a systematic study of the biomimetic hierarchical growth of hydroxyapatite (HA)/titania (TiO{sub 2}) nanocomposite layered coatings applied by a simple sol–gel dip coating method. Highly stable HA and TiO{sub 2} sols were prepared prior to inducing biomimetic hierarchical growth. Initially, the samples formed a small leaf like structure; however, increasing the dipping cycle resulted in formation of an elongated seed-like structure. Increasing the number of dipping cycles further resulted in a ‘bowtie’ or straw-bale like nanowire structure with a length of 500 nm and a width of 100 nm. Each nanowire like structure had a width of very few nanometers. The crystalline structures, micro/nano structures and surface properties of the coatings were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy respectively. In vitro cellular assays revealed that the growth of the cells in the ‘bowtie’ like structure improved over other samples.

  14. Synthesis of nickel hierarchical structures and evaluation on their magnetic properties and Congo red removal ability.

    Science.gov (United States)

    Zhang, Guangshu; Zhao, Lijun

    2013-03-14

    Novel nickel hierarchical structures were prepared through a facile one-pot solvothermal approach in the presence of surfactant and mineralizer. The influence of dynamics factors such as polyvinylpyrrolidone (PVP) content, ratio (R) between NaF and NH(3)·H(2)O on the morphologies of the as-synthesized products were investigated in detail. By regulating the dynamics factors, nickel crystals with three different structures (hcp and fcc mixture structure, fcc structure and a mostly hcp structure) were synthesized. Meanwhile, the corresponding morphologies are changed from hierarchical structures composed of nanoparticles to hierarchical structures consisted of nanoflakes, and to polyhedra. The values of saturation magnetizations of nickel crystals also range from 41.6 to 8 emu g(-1) because of the change of crystal structure from fcc to mostly hcp. One thing to be mentioned is that the mostly hcp phase can be completely converted into fcc phase if the solvothermal treatment temperature is further enhanced to 220 °C. Further, the Congo red (CR) removal ability by the as-obtained nickel particles was evaluated. By the investigation of adsorption and desorption experiments on nickel powders, we can ascertain that chemical reduction and physical adsorption happen at the same time during the treatment process of CR solution.

  15. INFOGRAPHIC MODELING OF THE HIERARCHICAL STRUCTURE OF THE MANAGEMENT SYSTEM EXPOSED TO AN INNOVATIVE CONFLICT

    Directory of Open Access Journals (Sweden)

    Chulkov Vitaliy Olegovich

    2012-12-01

    Full Text Available This article deals with the infographic modeling of hierarchical management systems exposed to innovative conflicts. The authors analyze the facts that serve as conflict drivers in the construction management environment. The reasons for innovative conflicts include changes in hierarchical structures of management systems, adjustment of workers to new management conditions, changes in the ideology, etc. Conflicts under consideration may involve contradictions between requests placed by customers and the legislation, any risks that may originate from the above contradiction, conflicts arising from any failure to comply with any accepted standards of conduct, etc. One of the main objectives of the theory of hierarchical structures is to develop a model capable of projecting potential innovative conflicts. Models described in the paper reflect dynamic changes in patterns of external impacts within the conflict area. The simplest model element is a monad, or an indivisible set of characteristics of participants at the pre-set level. Interaction between two monads forms a diad. Modeling of situations that involve a different number of monads, diads, resources and impacts can improve methods used to control and manage hierarchical structures in the construction industry. However, in the absence of any mathematical models employed to simulate conflict-related events, processes and situations, any research into, projection and management of interpersonal and group-to-group conflicts are to be performed in the legal environment

  16. Preparation and Properties of Monodisperse SnO2 Hollow Micro/Nano Spheres%单分散SnO2中空微纳米球的制备和性质

    Institute of Scientific and Technical Information of China (English)

    蔡宏敏; 任素贞; 王萌; 贾翠英

    2013-01-01

      模板法是制备无机中空微纳米球的重要方法之一。本文以苯乙烯为单体,通过乳液聚合得到粒径约为620 nm的单分散聚苯乙烯(PS)微球。以磺化后的聚苯乙烯(PSS)微球为模板,利用阴阳离子静电吸附作用,将PSS与前驱体SnSO4中的Sn2+结合。通过Sn2+在乙醇-水介质中的水解作用得到核-壳复合结构,再经高温煅烧,得到SnO2中空微纳米球。实验对前驱体的浓度、表面活性剂的用量、反应时间及模板选择等方面做了研究,通过扫描电镜(SEM)、X射线衍射(XRD)、红外(IR)光谱、热重分析(TGA)、H2程序升温还原(H2-TPR)、Brunauer-Emmett-Tel er (BET)比表面积等技术深入探究SnO2中空微纳米球的结构,并对比中空SnO2与实心粒子的氧化还原特性。 BET和H2-TPR显示将SnO2制备成微纳米空心球后其比表面积增大,表面氧空位明显增多,氧化活性明显提高。从IR及XRD推断核-壳结构形成机理,进而优化出简单合理的实验方案,获得表面光滑、结构致密,包覆厚度可控的SnO2中空微纳米球。%Templating is one of the most important methods for preparation of inorganic hol ow micro/nano spheres. We prepared monodisperse polystyrene (PS) microspheres having a diameter of 620 nm by the emulsion polymerization of styrene. Sulfonated polystyrene (PSS) microspheres were used as a template, through electrostatic adsorption of anions and cations, for modification with Sn2 + from SnSO4 precursor. The core-shel composite structures thereby produced through Sn2+ hydrolysis in an ethanol-water medium were calcined at high temperature to remove PSS and to obtain SnO2 hol ow micro/nano spheres. We investigated the effects of precursor concentration, amount of surfactant, reaction time, and templates choice. Scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared (IR) spectroscopy, thermogravimetric analysis (TGA), H2 temperature programmed

  17. Reliability and Hierarchical Structure of DSM-5 Pathological Traits in a Danish Mixed Sample

    DEFF Research Database (Denmark)

    Bo, Sune; Bach, Bo; Mortensen, Erik Lykke

    2016-01-01

    In this study we assessed the DSM-5 trait model in a large Danish sample (n = 1,119) with respect to reliability of the applied Danish version of the Personality Inventory for DSM-5 (PID-5) self-report form by means of internal consistency and item discrimination. In addition, we tested whether...... the five-factor structure of the DSM-5 trait model can be replicated in a Danish independent sample using the PID-5 self-report form. Finally, we examined the hierarchical structure of DSM-5 traits. In terms of internal consistency and item discrimination, the applied PID-5 scales were generally found...... reliable and functional; our data resembled the five-factor structure of previous findings, and we identified a hierarchical structure from one to five factors that was conceptually reasonable and corresponded with existing findings. These results support the new DSM-5 trait model and suggest that it can...

  18. Optical and photocatalytic properties of Mn doped flower-like ZnO hierarchical structures

    Science.gov (United States)

    Ma, Qun; Lv, Xiangzhou; Wang, Yongqian; Chen, Jieyu

    2016-10-01

    A novel Mn doped flower-like ZnO hierarchical structures were successfully synthesized with a facile ion-exchange method. Structural properties of the synthesized photocatalysis have been investigated with XRD, FESEM equipped with energy dispersive spectroscopy, while UV-vis and PL spectroscopy were employed to study their optical properties. The inner structure of doped ZnO hierarchical structure can be finely transformed from nanosheets to nanorods and to nanoparticles with the increasing of doping contents. All the synthesized Mn/ZnO samples exhibit strong blue-violet emission. Furthermore, the optical absorption towards visible light of ZnO was significantly enhanced due to the incorporation of Mn ions. The photocatalytic results indicate that photocatalytic activity of ZnO was enhanced with the doping of Mn and there is an optimum Mn doping level, leading to the highest photocatalytic performance.

  19. Hierarchical structure and cytocompatibility of fish scales from Carassius auratus

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhou [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, Yukun [State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory of Advanced Materials of Ministry of Education of China, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Kienzle, Arne; Müller, Werner E.G. [Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Johannes Gutenberg-Universität, Duesbergweg 6, Mainz 55099 (Germany)

    2014-10-01

    To study the structure and the cytocompatibility of fish scales from Carassius auratus, scanning electron microscopy (SEM) was used to observe the morphology of fish scales treated with different processing methods. Based on varying morphologies and components, the fish scales can be divided into three regions on the surface and three layers in vertical. The functions of these three individual layers were analyzed. SEM results show that the primary inorganic components are spherical or cubic hydroxyapatite (HA) nanoparticles. The fish scales have an ∼ 60° overlapped plywood structure of lamellas in the fibrillary plate. The plywood structure consists of co-aligned type I collagen fibers, which are parallel to the HA lamellas. X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and Fourier transform infrared (FTIR) analysis indicate that the main components are HA and type I collagen fibers. MC3T3-E1 cell culture results show a high cytocompatibility and the ability to guide cell proliferation and migration along the scale ridge channels of the fish scales. This plywood structure provides inspiration for a structure-enhanced composite material. - Highlights: • The Carassius auratus fish scale can be divided into 3 layers rather than 2. • The functions of these three individual layers were firstly analyzed. • The fish scale shows a high cytocompatibility. • The fish scale can guide cells migration along the scale ridge channels.

  20. Learning Hierarchical and Topographic Dictionaries with Structured Sparsity

    CERN Document Server

    Mairal, Julien; Obozinski, Guillaume; Bach, Francis; 10.1117/12.893811

    2011-01-01

    Recent work in signal processing and statistics have focused on defining new regularization functions, which not only induce sparsity of the solution, but also take into account the structure of the problem. We present in this paper a class of convex penalties introduced in the machine learning community, which take the form of a sum of l_2 and l_infinity-norms over groups of variables. They extend the classical group-sparsity regularization in the sense that the groups possibly overlap, allowing more flexibility in the group design. We review efficient optimization methods to deal with the corresponding inverse problems, and their application to the problem of learning dictionaries of natural image patches: On the one hand, dictionary learning has indeed proven effective for various signal processing tasks. On the other hand, structured sparsity provides a natural framework for modeling dependencies between dictionary elements. We thus consider a structured sparse regularization to learn dictionaries embedde...

  1. Hierarchically structured titania films for application in photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Niedermeier, M.A.; Kaune, G.; Mueller-Buschbaum, P. [TU Muenchen, Garching (Germany). Lehrstuhl fuer Funktionelle Materialien; Perlich, J. [TU Muenchen, Garching (Germany). Lehrstuhl fuer Funktionelle Materialien; DESY, Hamburg (Germany). HASYLAB; Memesa, M. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Gutmann, J.S. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany); Mainz Univ. (Germany). Inst. fuer Physikalische Chemie

    2010-07-01

    The fabrication of nanostructured titania films is investigated. The nanostructures are prepared using the diblock copolymer polystyrene-block-polyethyleneoxide (P(S-b-EO)) as a structure directing agent. Using repetitive sol-gel chemistry together with spin coating a thin polymer-nanocomposite film is deposited on silicon substrates which is calcined in air to obtain crystalline titania nanostructures. Furthermore, different types of morphologies are combined. The thus obtained structures are investigated regarding their morphologies, for example using imaging techniques like SEM. Additionally, information about the crystallinity is obtained with XRD. From our results we discuss the use of our films for photovoltaic applications. (orig.)

  2. TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium

    Directory of Open Access Journals (Sweden)

    Iwasa F

    2011-06-01

    Full Text Available Fuminori Iwasa1, Naoki Tsukimura1, Yoshihiko Sugita1, Rajita Kodali Kanuru1, Katsutoshi Kubo1, Hafiz Hasnain1, Wael Att1,2, Takahiro Ogawa11Laboratory of Bone and Implant Sciences (LBIS, The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Prosthodontics, Dental School, Albert-Ludwigs University, Freiburg, GermanyAbstract: Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO2 nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow–derived osteoblasts were cultured on fresh disks (immediately after UV treatment, 3-day-old disks (disks stored for 3 days after UV treatment, and 7-day-old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%–50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano-hybrid surfaces became hydrorepellent

  3. Kendall’s tau and agglomerative clustering for structure determination of hierarchical Archimedean copulas

    Directory of Open Access Journals (Sweden)

    Górecki J.

    2017-01-01

    Full Text Available Several successful approaches to structure determination of hierarchical Archimedean copulas (HACs proposed in the literature rely on agglomerative clustering and Kendall’s correlation coefficient. However, there has not been presented any theoretical proof justifying such approaches. This work fills this gap and introduces a theorem showing that, given the matrix of the pairwise Kendall correlation coefficients corresponding to a HAC, its structure can be recovered by an agglomerative clustering technique.

  4. Hierarchical MoS2-rGO nanosheets with high MoS2 loading with enhanced electro-catalytic performance

    Science.gov (United States)

    Zhou, Jing; Xiao, Han; Zhou, Bowen; Huang, Feifan; Zhou, Shoubin; Xiao, Wei; Wang, Dihua

    2015-12-01

    Incorporation of high-loading redox-active materials with small amounts of graphene is a general protocol to achieve high-performance catalysts. Herein, hierarchical MoS2-reduced graphene oxide nanosheet (denoted as MoS2-rGO nanosheets) hybrids with a loading of MoS2 as high as 94 wt% are synthesized. The obtained hierarchical MoS2-rGO nanosheets simultaneously integrate the structural and compositional design rationales for high-efficiency and durable electrocatalysts based on high weight ratio of MoS2 in hybrid composite, highly stable/conducting rGO, well-dispersed two-dimensional ultrathin MoS2 nanosheets, more exposed edge sites and micro/nano hierarchical structure. When evaluated as electrocatalysts for hydrogen evolution and oxygen reduction reactions, the hierarchical MoS2-rGO nanosheets demonstrates enhanced activity and excellent stability, promising their applications in MoS2 based electrochemical, photo-catalytic and photo-elecrocatalytic cells.

  5. An XML-hierarchical data structure for ENSDF

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, Aaron M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-03-15

    A data structure based on an eXtensible Markup Language (XML) hierarchy according to experimental nuclear structure data in the Evaluated Nuclear Structure Data File (ENSDF) is presented. A Python-coded translator has been developed to interpret the standard one-card records of the ENSDF datasets, together with their associated quantities defined according to field position, and generate corresponding representative XML output. The quantities belonging to this mixed-record format are described in the ENSDF manual. Of the 16 ENSDF records in total, XML output has been successfully generated for 15 records. An XML-translation for the Comment Record is yet to be implemented; this will be considered in a separate phase of the overall translation effort. Continuation records, not yet implemented, will also be treated in a future phase of this work. Several examples are presented in this document to illustrate the XML schema and methods for handling the various ENSDF data types. However, the proposed nomenclature for the XML elements and attributes need not necessarily be considered as a fixed set of constructs. Indeed, better conventions may be suggested and a consensus can be achieved amongst the various groups of people interested in this project. The main purpose here is to present an initial phase of the translation effort to demonstrate the feasibility of interpreting ENSDF datasets and creating a representative XML-structured hierarchy for data storage.

  6. Hierarchical structure formation in supramolecular comb-shaped block copolymers

    NARCIS (Netherlands)

    Hofman, Anton; ten Brinke, Gerrit; Loos, Katja

    2016-01-01

    Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such al

  7. Synthesis and structural characterization of two-dimensional hierarchical covellite nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Nirupam, E-mail: n.banerjee@utwente.nl [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); MESA Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-14

    We report a simple, template free and low-temperature hydrothermal reaction pathway using Cu(II) - thiourea complex (prepared in situ from copper (II) chloride and thiourea as precursors) and citric acid as complexing agent to synthesize two-dimensional hierarchical nano-structures of covellite (CuS). The product was characterized with the help of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS). The concentration of citric acid in the hydrothermal precursor solution was seen to have a profound effect on the nanostructure of the product generated. Based on the outcoming product nano-architecture at different concentration of the ionic surfactant in the hydrothermal precursor solution a possible mechanism suited for reaction and further nucleation is also discussed. -- Highlights: Black-Right-Pointing-Pointer A novel reaction scheme is proposed for synthesizing covellite 2D nano-structures. Black-Right-Pointing-Pointer The nanostructures were thoroughly characterized, both structurally and chemically. Black-Right-Pointing-Pointer Through variation of synthetic parameters a general growth mechanism is proposed.

  8. Facile synthesis of Zn doped CuO hierarchical nanostructures: Structural, optical and antibacterial properties

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Javed, E-mail: tariqjan84@gmail.com, E-mail: javed.suggau@iiu.edu.pk; Jan, Tariq, E-mail: tariqjan84@gmail.com, E-mail: javed.suggau@iiu.edu.pk; Ul-Hassan, Sibt; Umair Ali, M.; Abbas, Fazal [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University, H-10, Islamabad (Pakistan); Ahmed, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan); Mansoor, Qaisar; Ismail, Muhammad [Institute of Biomedical and Genetic Engineering (IBGE), Islamabad (Pakistan)

    2015-12-15

    Zn{sub x}Cu{sub 1−x}O (where x= 0, 0.01, 0.03, 0.05, 0.07 and 0.1 mol%) hierarchical nanostructures have been prepared via soft chemical route. X-ray diffraction (XRD) results of the synthesized samples reveal the monoclinic structure of CuO without any impurity related phases. The micro-structural parameters such as crystallite size and microstrain have been strongly influenced by Zn doping. Scanning electron microscope (SEM) analyses depict the formation of hierarchical nanostructures having average particle size in the range of 26-43 nm. The surface area of CuO nanostructures has been reduced systematically with the increase in Zn content which is linked with the variations in particle size. An obvious decrease in the optical band gap energy of the synthesized CuO hierarchical nanostructures has been observed with Zn doping which is assigned to the formation of shallow levels in the band gap of CuO and combined transition from oxygen 2p states to d sates of Cu and Zn ions. The bactericidal potency of the CuO hierarchical nanostructures have been found to be enhanced remarkably with Zn doping.

  9. Modular networks with hierarchical organization: The dynamical implications of complex structure

    Indian Academy of Sciences (India)

    Raj Kumar Pan; Sitabhra Sinha

    2008-08-01

    Several networks occurring in real life have modular structures that are arranged in a hierarchical fashion. In this paper, we have proposed a model for such networks, using a stochastic generation method. Using this model we show that, the scaling relation between the clustering and degree of the nodes is not a necessary property of hierarchical modular networks, as had previously been suggested on the basis of a deterministically constructed model. We also look at dynamics on such networks, in particular, the stability of equilibria of network dynamics and of synchronized activity in the network. For both of these, we find that, increasing modularity or the number of hierarchical levels tends to increase the probability of instability. As both hierarchy and modularity are seen in natural systems, which necessarily have to be robust against environmental fluctuations, we conclude that additional constraints are necessary for the emergence of hierarchical structure, similar to the occurrence of modularity through multi-constraint optimization as shown by us previously.

  10. Dielectric study on hierarchical water structures restricted in cement and wood materials

    Science.gov (United States)

    Abe, Fumiya; Nishi, Akihiro; Saito, Hironobu; Asano, Megumi; Watanabe, Seiei; Kita, Rio; Shinyashiki, Naoki; Yagihara, Shin; Fukuzaki, Minoru; Sudo, Seiichi; Suzuki, Youki

    2017-04-01

    Dielectric relaxation processes for mortar observed by broadband dielectric spectroscopy were analyzed in the drying and hydration processes for an aging sample in the frequency region from 1 MHz up to 2 MHz. At least two processes for structured water in the kHz frequency region and another mHz relaxation process affected by ionic behaviors were observed. Comparison of the relaxation parameters obtained for the drying and hydration processes suggests an existence of hierarchical water structures in the exchange of water molecules, which are originally exchanged from free water observed at around 20 GHz. The water molecules reflected in the lower frequency process of the two kHz relaxation processes are more restricted and take more homogeneous structures than the higher kHz relaxation process. These structured water usually hidden in large ionic behaviors for wood samples was observed by electrodes covered by a thin Teflon film, and hierarchical water structures were also suggested for wood samples. Dielectric spectroscopy technique is an effective tool to analyze the new concept of hierarchical water structures in complex materials.

  11. Hierarchical Structures from Inorganic Nanocrystal Self-Assembly for Photoenergy Utilization

    Directory of Open Access Journals (Sweden)

    Yun-Pei Zhu

    2014-01-01

    Full Text Available Self-assembly has emerged as a powerful strategy for controlling the structure and physicochemical properties of ensembles of inorganic nanocrystals. Hierarchical structures from nanocrystal assembly show collective properties that differ from individual nanocrystals and bulk samples. Incorporation of structural hierarchy into nanostructures is of great importance as a result of enhancing mass transportation, reducing resistance to diffusion, and high surface areas for adsorption and reaction, and thus much effort has been devoted to the exploration of various novel organizing schemes through which inorganic porous structure with architectural design can be created. In this paper, the recent research progress in this field is reviewed. The general strategies for the synthesis of hierarchical structures assembled from nanobuilding blocks are elaborated. The well-defined hierarchical structures provide new opportunities for optimizing, tuning, and/or enhancing the properties and performance of these materials and have found applications in photoenergy utilization including photodegradation, photocatalytic H2 production, photocatalytic CO2 conversion, and sensitized solar cells, and these are discussed illustratively.

  12. Prediction of Halocarbon Toxicity from Structure: A Hierarchical QSAR Approach

    Energy Technology Data Exchange (ETDEWEB)

    Gute, B D; Balasubramanian, K; Geiss, K; Basak, S C

    2003-04-11

    Mathematical structural invariants and quantum theoretical descriptors have been used extensively in quantitative structure-activity relationships (QSARs) for the estimation of pharmaceutical activities, biological properties, physicochemical properties, and the toxicities of chemicals. Recently our research team has explored the relative importance of various levels of chemodescriptors, i.e., topostructural, topochemical, geometrical, and quantum theoretical descriptors, in property estimation. This study examines the contribution of chemodescriptors ranging from topostructural to quantum theoretic calculations up to the Gaussian STO-3G level in the prediction of the toxicity of a set of twenty halocarbons. We also report the results of experimental cell-level toxicity studies on these twenty halocarbons to validate our models.

  13. Hierarchical Sets: Analyzing Pangenome Structure through Scalable Set Visualizations

    OpenAIRE

    Pedersen, Thomas Lin

    2017-01-01

    The increase in available microbial genome sequences has resulted in an increase in the size of the pangenomes being analyzed. Current pangenome visualizations are not intended for the pangenome sizes possible today and new approaches are necessary in order to convert the increase in available information to increase in knowledge. As the pangenome data structure is essentially a collection of sets we explore the potential for scalable set visualization as a tool for pangenome analysis. We pre...

  14. Fractal analysis of the hierarchic structure of fossil coal surface

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.D.; Vasilenko, T.A.; Kirillov, A.K. [National Academy of Sciences, Donetsk (Ukraine)

    2008-05-15

    The fractal analysis is described as method of studying images of surface of fossil coal, one of the natural sorbent, with the aim of determining its structural surface heterogeneity. The deformation effect as a reduction in the dimensions of heterogeneity boundaries is considered. It is shown that the theory of nonequilibrium dynamic systems permits to assess a formation level of heterogeneities involved into a sorbent composition by means of the Hurst factor.

  15. Mechanical Properties of Zirconium Ceramics with Hierarchical Porous Structure

    Science.gov (United States)

    Kulkov, S.; Shutilova, E.; Buyakova, S.

    2016-07-01

    The work studies porous ceramics produced from ultra-fine powders. The porosity of ceramic samples was from 15 to 80%. The ceramic materials had cellular structure. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations, which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformations on deformation diagrams is due to mechanical instability of cellular elements in a ceramic frame.

  16. Hierarchical surface atomic structure of a manganese-based spinel cathode for lithium-ion batteries.

    Science.gov (United States)

    Lee, Sanghan; Yoon, Gabin; Jeong, Minseul; Lee, Min-Joon; Kang, Kisuk; Cho, Jaephil

    2015-01-19

    The increasing use of lithium-ion batteries (LIBs) in high-power applications requires improvement of their high-temperature electrochemical performance, including their cyclability and rate capability. Spinel lithium manganese oxide (LiMn2O4) is a promising cathode material because of its high stability and abundance. However, it exhibits poor cycling performance at high temperatures owing to Mn dissolution. Herein we show that when stoichiometric lithium manganese oxide is coated with highly doped spinels, the resulting epitaxial coating has a hierarchical atomic structure consisting of cubic-spinel, tetragonal-spinel, and layered structures, and no interfacial phase is formed. In a practical application of the coating to doped spinel, the material retained 90% of its capacity after 800 cycles at 60 °C. Thus, the formation of an epitaxial coating with a hierarchical atomic structure could enhance the electrochemical performance of LIB cathode materials while preventing large losses in capacity.

  17. Structure-function relationships in Macadamia integrifolia seed coats--fundamentals of the hierarchical microstructure.

    Directory of Open Access Journals (Sweden)

    Paul Schüler

    Full Text Available The shells/coats of nuts and seeds are often very hard to crack. This is particularly the case with Macadamia seed coats, known to exhibit astoundingly high strength and toughness. We performed an extensive materials science characterization of the complex hierarchical structure of these coats, using light and scanning electron microscopy in 2D as well as microCT for 3D characterization. We differentiate nine hierarchical levels that characterize the structure ranging from the whole fruit on the macroscopic scale down to the molecular scale. From a biological viewpoint, understanding the hierarchical structure may elucidate why it is advantageous for these seed coats to be so difficult to break. From an engineering viewpoint, microstructure characterization is important for identifying features that contribute to the high strength and cracking resistance of these objects. This is essential for revealing the underlying structure-function-relationships. Such information will help us develop engineering materials and lightweight-structures with improved fracture and puncture resistance.

  18. Hierarchical photonic structured stimuli-responsive materials as high-performance colorimetric sensors.

    Science.gov (United States)

    Lu, Tao; Zhu, Shenmin; Chen, Zhixin; Wang, Wanlin; Zhang, Wang; Zhang, Di

    2016-05-21

    Hierarchical photonic structures in nature are of special interest because they can be used as templates for fabrication of stimuli-responsive photonic crystals (PCs) with unique structures beyond man-made synthesis. The current stimuli-responsive PCs templated directly from natural PCs showed a very weak external stimuli response and poor durability due to the limitations of natural templates. Herein, we tackle this problem by chemically coating functional polymers, polyacrylamide, on butterfly wing scales which have hierarchical photonic structures. As a result of the combination of the strong water absorption properties of the polyacrylamide and the PC structures of the butterfly wing scales, the designed materials demonstrated excellent humidity responsive properties and a tremendous colour change. The colour change is induced by the refractive index change which is in turn due to the swollen nature of the polymer when the relative humidity changes. The butterfly wing scales also showed an excellent durability which is due to the chemical bonds formed between the polymer and wing scales. The synthesis strategy provides an avenue for the promising applications of stimuli-responsive PCs with hierarchical structures.

  19. Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Ruixia; Song, Xueling; Li, Jia; Yang, Ping, E-mail: mse_yangp@ujn.edu.cn

    2015-04-15

    Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity. - Highlights: • Hierarchical ZnO constructed by twinned structures have been synthesized. • The formation mechanisms of ZnO with twinned structure were discussed. • Football-like microspheres were obtained due to the slower nucleation and growth. • Hamburger-like ZnO was formed due to the amount of initial nuclei and growth units. • Pore sizes have important effects on the photocatalytic activity of sample.

  20. Superhydrophobic hierarchically structured surfaces in biology: evolution, structural principles and biomimetic applications

    Science.gov (United States)

    Mail, M.; Neinhuis, C.

    2016-01-01

    A comprehensive survey of the construction principles and occurrences of superhydrophobic surfaces in plants, animals and other organisms is provided and is based on our own scanning electron microscopic examinations of almost 20 000 different species and the existing literature. Properties such as self-cleaning (lotus effect), fluid drag reduction (Salvinia effect) and the introduction of new functions (air layers as sensory systems) are described and biomimetic applications are discussed: self-cleaning is established, drag reduction becomes increasingly important, and novel air-retaining grid technology is introduced. Surprisingly, no evidence for lasting superhydrophobicity in non-biological surfaces exists (except technical materials). Phylogenetic trees indicate that superhydrophobicity evolved as a consequence of the conquest of land about 450 million years ago and may be a key innovation in the evolution of terrestrial life. The approximate 10 million extant species exhibit a stunning diversity of materials and structures, many of which are formed by self-assembly, and are solely based on a limited number of molecules. A short historical survey shows that bionics (today often called biomimetics) dates back more than 100 years. Statistical data illustrate that the interest in biomimetic surfaces is much younger still. Superhydrophobicity caught the attention of scientists only after the extreme superhydrophobicity of lotus leaves was published in 1997. Regrettably, parabionic products play an increasing role in marketing. This article is part of the themed issue ‘Bioinspired hierarchically structured surfaces for green science’. PMID:27354736

  1. Superhydrophobic hierarchically structured surfaces in biology: evolution, structural principles and biomimetic applications.

    Science.gov (United States)

    Barthlott, W; Mail, M; Neinhuis, C

    2016-08-06

    A comprehensive survey of the construction principles and occurrences of superhydrophobic surfaces in plants, animals and other organisms is provided and is based on our own scanning electron microscopic examinations of almost 20 000 different species and the existing literature. Properties such as self-cleaning (lotus effect), fluid drag reduction (Salvinia effect) and the introduction of new functions (air layers as sensory systems) are described and biomimetic applications are discussed: self-cleaning is established, drag reduction becomes increasingly important, and novel air-retaining grid technology is introduced. Surprisingly, no evidence for lasting superhydrophobicity in non-biological surfaces exists (except technical materials). Phylogenetic trees indicate that superhydrophobicity evolved as a consequence of the conquest of land about 450 million years ago and may be a key innovation in the evolution of terrestrial life. The approximate 10 million extant species exhibit a stunning diversity of materials and structures, many of which are formed by self-assembly, and are solely based on a limited number of molecules. A short historical survey shows that bionics (today often called biomimetics) dates back more than 100 years. Statistical data illustrate that the interest in biomimetic surfaces is much younger still. Superhydrophobicity caught the attention of scientists only after the extreme superhydrophobicity of lotus leaves was published in 1997. Regrettably, parabionic products play an increasing role in marketing.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'. © 2016 The Author(s).

  2. Ultrahigh stress and strain in hierarchically structured hollow nanoparticles

    Science.gov (United States)

    Shan, Z. W.; Adesso, G.; Cabot, A.; Sherburne, M. P.; Syed Asif, S. A.; Warren, O. L.; Chrzan, D. C.; Minor, A. M.; Alivisatos, A. P.

    2008-12-01

    Nanocrystalline materials offer very high strength but are typically limited in their strain to failure, and efforts to improve deformability in these materials are usually found to be at the expense of strength. Using a combination of quantitative in situ compression in a transmission electron microscope and finite-element analysis, we show that the mechanical properties of nanoparticles can be directly measured and interpreted on an individual basis. We find that nanocrystalline CdS synthesized into a spherical shell geometry is capable of withstanding extreme stresses (approaching the ideal shear strength of CdS). This unusual strength enables the spherical shells to exhibit considerable deformation to failure (up to 20% of the sphere's diameter). By taking into account the structural hierarchy intrinsic to novel nanocrystalline materials such as this, we show it is possible to achieve and characterize the ultrahigh stresses and strains that exist within a single nanoparticle during deformation.

  3. A Generic Identification Scheme for Hierarchically Structured Objects

    Institute of Scientific and Technical Information of China (English)

    ChristianArnault; StanBentvelsen; 等

    2001-01-01

    The detector description database,the event data structure,the condition database are all examples(among others)of complex collections of objects which need to be unambiguously identified,not only internally to their own management structure.but also from one collection to the other.The requirements for such an identification scheme include the management of identifiers individually attached to each collected object,the possibility to formally spectify these identifiers (eg through dictionaries),to generate optimised and compact representations for these identifiers and to be able to use them as sorting and searching keys.we present here the generic toolkit developed in the context of the Atlas experiment to primarily provide the identification of the readout elements of the detector.This toolkit offers several either generic or specialized component such as:an XML based dictionary with which the formal specification of a particular object collection is expressed,a set of various binary representations for identifier objects(offering various level of compaction),range operators meant to manipulate ranges of identifiers,and finally a collection manager similar to the STL map but optimised for an organization keyed by Identifiers.All these components easily interoperate.In Particular the Identifier didctionary offers means of specifying permitted cardinalities of objects at each level of the hierarchy,This can then be translated into Identifier Ranges or can be used as the strategy driver for high compactification of the identifiers(e.g.to store very large number of identified objects).Current use of this toolkit within the detector description will be presented,and expected or possible other usages will be discussed.

  4. 反应温度对隐甲锰矿型MnO2微纳结构和超级电容性能的影响∗%The effect of reaction temperature on the micro-nano structure and the capacitance properties of cryptomelane-type manganese oxide

    Institute of Scientific and Technical Information of China (English)

    冉奋; 康龙; 刘影; 王翎任; 刘卯成; 张宣宣; 范会利; 宋海明; 申魁文; 孔令斌

    2015-01-01

    采用简单的水热法制备了具有均一八面分子筛(OMS-2)结构的隐甲锰矿型二氧化锰(MnO2);通过水热反应温度控制 Mn O 2的微纳结构,研究反应温度对其超级电容器性能的影响。采用扫描电子显微镜(SEM)、X 射线衍射(XRD)和透射电子显微镜(TEM)表征材料的结构特点;采用循环伏安和恒流充放电测试其电化学电容性能。结果表明,制备的Mn O 2具有纳米刺或纳米棒形成放射状结构,随着反应温度的增加,Mn O 2晶体逐渐生长完全,从针状纳米刺转变成四方形纳米棒;制备的 Mn O 2具有双电层电容和法拉第准电容的双重特征,在5 mA/cm2的电流密度下,最高比电容达到了603 F/g;在100~180℃的范围内,比容量随着反应温度的升高而逐渐降低。%In this article,the uniform cryptomelane-type manganese oxide with an octahedral molecular sieves structure was prepared under mild hydrothermal condition;the effects of hydrothermal temperature on the mi-cro-nanostructure and supercapacitance properties of manganese dioxide were studied in detail.The structures were characterized by SEM,XRD and TEM;and the supercapacitive behaviors were investigated with cyclic voltammetry,galvanostatic charge and discharge tests.The experiment results suggested that:the prepared nanoparticles can be self-organized into dendritic nanostructures,and the nanocluster arrays are composed of nanoneedles or tetragonal prism nanorods;with the increase of reaction temprature,the crystal morphology of manganese oxide was gradually improving,and was trasformed from nanoneedles to tetragonal prism nanorods;the capacitance of MnO2 electrode was a combined contribution of electrical double-layer capacitance and pseud-ocapacitance,and the best specific capacitance value of MnO2 electrode was 603 F/g corresponding to the charge/discharge current density of 5 mA/cm2;with the increase of reaction temperature ranging from 100-180℃,the specific capacitance

  5. Hierarchical structure of the Sicilian goats revealed by Bayesian analyses of microsatellite information.

    Science.gov (United States)

    Siwek, M; Finocchiaro, R; Curik, I; Portolano, B

    2011-02-01

    Genetic structure and relationship amongst the main goat populations in Sicily (Girgentana, Derivata di Siria, Maltese and Messinese) were analysed using information from 19 microsatellite markers genotyped on 173 individuals. A posterior Bayesian approach implemented in the program STRUCTURE revealed a hierarchical structure with two clusters at the first level (Girgentana vs. Messinese, Derivata di Siria and Maltese), explaining 4.8% of variation (amovaФ(ST) estimate). Seven clusters nested within these first two clusters (further differentiations of Girgentana, Derivata di Siria and Maltese), explaining 8.5% of variation (amovaФ(SC) estimate). The analyses and methods applied in this study indicate their power to detect subtle population structure.

  6. Complexity of major UK companies between 2006 and 2010: Hierarchical structure method approach

    Science.gov (United States)

    Ulusoy, Tolga; Keskin, Mustafa; Shirvani, Ayoub; Deviren, Bayram; Kantar, Ersin; Çaǧrı Dönmez, Cem

    2012-11-01

    This study reports on topology of the top 40 UK companies that have been analysed for predictive verification of markets for the period 2006-2010, applying the concept of minimal spanning tree and hierarchical tree (HT) analysis. Construction of the minimal spanning tree (MST) and the hierarchical tree (HT) is confined to a brief description of the methodology and a definition of the correlation function between a pair of companies based on the London Stock Exchange (LSE) index in order to quantify synchronization between the companies. A derivation of hierarchical organization and the construction of minimal-spanning and hierarchical trees for the 2006-2008 and 2008-2010 periods have been used and the results validate the predictive verification of applied semantics. The trees are known as useful tools to perceive and detect the global structure, taxonomy and hierarchy in financial data. From these trees, two different clusters of companies in 2006 were detected. They also show three clusters in 2008 and two between 2008 and 2010, according to their proximity. The clusters match each other as regards their common production activities or their strong interrelationship. The key companies are generally given by major economic activities as expected. This work gives a comparative approach between MST and HT methods from statistical physics and information theory with analysis of financial markets that may give new valuable and useful information of the financial market dynamics.

  7. Microwave-assisted synthesis and characterization of hierarchically structured calcium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhenxing [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China); Wang, Guangjian, E-mail: wgj2260@chnu.edu.cn [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China); Guo, Yajie; Kang, Fangfang; Huang, Yanhong; Bo, Dongsheng [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China)

    2012-12-15

    Graphical abstract: CaF{sub 2} with different morphologies and hierarchical structure such as dendrites, spherical and cube was prepared under microwave-assisted condition by a simple solvothermal synthesis route using CaCl{sub 2} and [BMIM]BF{sub 4} as initial reagents, respectively. It was found that the species of precursor was of vital importance for the formation of CaF{sub 2} crystals. That is, precursors itself also acted as structure directing agent. The outstanding features of the approach to obtain hierarchical structure CaF{sub 2} were its simplicity, effectiveness and ease of assembly. On the basis of the experimental results, a possible growth mechanism of the CaF{sub 2} crystals was proposed. Display Omitted Highlights: ► CaF{sub 2} with hierarchical structure was synthesized under microwave-assisted conditions. ► Characteristic morphologies with cube, dendrite, hierarchical sphere, etc. were observed. ► Thin cubes assembled into a spherical structure. ► Ionic liquid of [BMIM]BF{sub 4} was fluorine source. ► Possible growth mechanisms of CaF{sub 2} crystals were discussed. -- Abstract: CaF{sub 2} with different morphologies and hierarchical structures was prepared under microwave-assisted condition by a simple hydrothermal route using CaCl{sub 2} and ionic liquid [BMIM]BF{sub 4} as initial reagents, respectively. It was found that both the precursor and pH values played an important role in the formation of CaF{sub 2} crystals with different morphologies. The results suggested that the CaF{sub 2} with cube and spherical structures was obtained at different pH values (4, 8, 11), while the CaF{sub 2} with dendrite shape was formed through an oriented self-assembly growth using (NH{sub 4}){sub 2}HPO{sub 4} as a structure directing agent. Scanning electron microscope observation showed that the as-prepared CaF{sub 2} was of three-dimensional eight-horn-shaped dendritic structure. The influence of the pH values for the reaction solution and

  8. Assessing the multidimensional and hierarchical structure of SERVQUAL.

    Science.gov (United States)

    Ma, Jun; Harvey, Milton E; Hu, Michael Y

    2007-10-01

    Parasuraman, Zeithaml, and Berry introduced SERVQUAL in 1998 as a scale to measure service quality. Since then, researchers have proposed several variations. This study examines the development of the tool. Marketing researchers have first challenged the conceptualization of a perceptions-expectations gap and have concluded that the performance-based measures are adequate to capture consumers' perception of service quality. Some researchers have argued that the five dimensions of the SERVQUAL scale only focus on the process of service delivery and have extended the SERVQUAL scale into six dimensions by including the service outcome dimension. Others have proposed that service quality is a multilevel construct and should be measured accordingly. From a sample of 467 undergraduate students data on service quality toward up-scale restaurants were collected. Using the structural equation approach, two measurement models of service quality were compared, the extended SERVQUAL model and the restructured multilevel SERVQUAL model. Analysis suggested that the latter model fits the data better than the extended one.

  9. Superhydrophobic surface based on a coral-like hierarchical structure of ZnO.

    Directory of Open Access Journals (Sweden)

    Jun Wu

    Full Text Available BACKGROUND: Fabrication of superhydrophobic surfaces has attracted much interest in the past decade. The fabrication methods that have been studied are chemical vapour deposition, the sol-gel method, etching technique, electrochemical deposition, the layer-by-layer deposition, and so on. Simple and inexpensive methods for manufacturing environmentally stable superhydrophobic surfaces have also been proposed lately. However, work referring to the influence of special structures on the wettability, such as hierarchical ZnO nanostructures, is rare. METHODOLOGY: This study presents a simple and reproducible method to fabricate a superhydrophobic surface with micro-scale roughness based on zinc oxide (ZnO hierarchical structure, which is grown by the hydrothermal method with an alkaline aqueous solution. Coral-like structures of ZnO were fabricated on a glass substrate with a micro-scale roughness, while the antennas of the coral formed the nano-scale roughness. The fresh ZnO films exhibited excellent superhydrophilicity (the apparent contact angle for water droplet was about 0°, while the ability to be wet could be changed to superhydrophobicity after spin-coating Teflon (the apparent contact angle greater than 168°. The procedure reported here can be applied to substrates consisting of other materials and having various shapes. RESULTS: The new process is convenient and environmentally friendly compared to conventional methods. Furthermore, the hierarchical structure generates the extraordinary solid/gas/liquid three-phase contact interface, which is the essential characteristic for a superhydrophobic surface.

  10. Hierarchical structure of the countries based on electricity consumption and economic growth

    Science.gov (United States)

    Kantar, Ersin; Aslan, Alper; Deviren, Bayram; Keskin, Mustafa

    2016-07-01

    We investigate the hierarchical structures of countries based on electricity consumption and economic growth by using the real amounts of their consumption over a certain time period. We use electricity consumption data to detect the topological properties of 64 countries from 1971 to 2008. These countries are divided into three clusters: low income group, middle income group and high income group countries. Firstly, a relationship between electricity consumption and economic growth is investigated by using the concept of hierarchical structure methods (minimal spanning tree (MST) and hierarchical tree (HT)). Secondly, we perform bootstrap techniques to investigate a value of the statistical reliability to the links of the MST. Finally, we use a clustering linkage procedure in order to observe the cluster structure more clearly. The results of the structural topologies of these trees are as follows: (i) we identified different clusters of countries according to their geographical location and economic growth, (ii) we found a strong relation between energy consumption and economic growth for all the income groups considered in this study and (iii) the results are in good agreement with the causal relationship between electricity consumption and economic growth.

  11. Hierarchically structured composites for ultrafast liquid sensing and smart leak-plugging.

    Science.gov (United States)

    Wu, Xiaodong; Han, Yangyang; Zhang, Xinxing; Lu, Canhui

    2017-06-21

    Conductive polymer composites (CPCs) have been intensively exploited as remarkable liquid sensing materials based on variations in their conductivity under liquid stimuli. However, most advances in liquid sensing CPCs are limited to bulk materials. Due to the slow permeation of liquids into the compact CPCs, sluggish responses are inevitable for most existing CPC-based liquid sensing materials. Here, we developed a new class of liquid sensing materials via a hierarchical structure design. Specifically, a thin CPC layer with a segregated conductive network was coated on porous polyurethane (PU) skeletons by layer-by-layer assembly, forming an elaborately designed hierarchical structure in the prepared CPC@PU composites. With this hierarchical structure, the CPC@PU composites exhibited ultrafast responses (0.05-0.15 s) to solvent stimuli, which are ∼3 orders of magnitude faster than the state-of-the-art composites. After liquid sensing, quick regeneration (within 10 s) could be achieved under hot-air. Accordingly, organic liquid and gas sensors and liquid-sensing electronic skins were fabricated. Furthermore, we prepared smart and fast leak-plugging materials using the CPC@PU composites based on the swelling-induced blocking of micropores in the materials. This structural strategy proposed here opens up exciting avenues towards manufacturing real-time liquid sensing and plugging materials, revealing potential applications in oilfield exploitation, solvent storage/transportation, environmental monitoring, etc.

  12. Hierarchically structured carbon nanotubes for energy conversion and storage

    Science.gov (United States)

    Du, Feng

    As the world population continues to increase, large amounts of energy are consumed. Reality pushes us to find new energy or use our current energy more efficiently. Researches on energy conversion and storage have become increasingly important and essential. This grand challenge research has led to a recent focus on nanostructured materials. Carbon nanomaterials such as carbon nanotubes (CNTs) play a critical role in all of these nanotechnology challenges. CNTs have a very large surface area, a high electrochemical accessibility, high electronic conductivity and strong mechanical properties. This combination of properties makes them promising materials for energy device applications, such as FETs, supercapacitors, fuel cells, and lithium batteries. This study focuses on exploring the possibility of using vertically aligned carbon nanotubes (VA-CNTs) as the electrode materials in these energy applications. For the application of electrode materials, electrical conductive, vertically aligned CNTs with controllable length and diameter were synthesized. Several CVD methods for VA-CNT growth have been explored, although the iron / aluminum pre-coated catalyst CVD system was the main focus. A systematic study of several factors, including growth time, temperature, gas ratio, catalyst coating was conducted. The mechanism of VA-CNTs was discussed and a model for VA-CNT length / time was proposed to explain the CNT growth rate. Furthermore, the preferential growth of semiconducting (up to 96 atom% carbon) VA-SWNTs by using a plasma enhanced CVD process combined with fast heating was also explored, and these semiconducting materials have been directly used for making FETs using simple dispersion in organic solvent, without any separation and purification. Also, by inserting electron-accepting nitrogen atoms into the conjugated VA-CNT structure during the growth process, we synthesized vertically aligned nitrogen containing carbon nanotubes (VA-NCNTs). After purification of

  13. CTAB-Assisted Hydrothermal Synthesis of WO3 Hierarchical Porous Structures and Investigation of Their Sensing Properties

    Directory of Open Access Journals (Sweden)

    Dan Meng

    2015-01-01

    Full Text Available WO3 hierarchical porous structures were successfully synthesized via cetyltrimethylammonium bromide- (CTAB- assisted hydrothermal method. The structure and morphology were investigated using scanning electron microscope, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectra, Brunauer-Emmett-Teller nitrogen adsorption-desorption, and thermogravimetry and differential thermal analysis. The result demonstrated that WO3 hierarchical porous structures with an orthorhombic structure were constructed by a number of nanoparticles about 50–100 nm in diameters. The H2 gas sensing measurements showed that well-defined WO3 hierarchical porous structures with a large specific surface area exhibited the higher sensitivity compared with products without CTAB at all operating temperatures. Moreover, the reversible and fast response to H2 gas and good selectivity were obtained. The results indicated that the WO3 hierarchical porous structures are promising materials for gas sensors.

  14. Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute

    Science.gov (United States)

    Xu, Ting; Kao, Joseph

    2016-11-08

    Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. The assembly kinetics of supramolecular nanocomposite in thin films is governed by the energetic cost arising from defects, the chain mobility, and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in approximately one minute. Moreover, the strong wavelength dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present invention opens a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films.

  15. Hierarchically structured photonic crystals for integrated chemical separation and colorimetric detection.

    Science.gov (United States)

    Fu, Qianqian; Zhu, Biting; Ge, Jianping

    2017-02-16

    A SiO2 colloidal photonic crystal film with a hierarchical porous structure is fabricated to demonstrate an integrated separation and colorimetric detection of chemical species for the first time. This new photonic crystal based thin layer chromatography process requires no dyeing, developing and UV irradiation compared to the traditional TLC. The assembling of mesoporous SiO2 particles via a supersaturation-induced-precipitation process forms uniform and hierarchical photonic crystals with micron-scale cracks and mesopores, which accelerate the diffusion of developers and intensify the adsorption/desorption between the analytes and silica for efficient separation. Meanwhile, the chemical substances infiltrated to the voids of photonic crystals cause an increase of the refractive index and a large contrast of structural colors towards the unloaded part, so that the sample spots can be directly recognized with the naked eye before and after separation.

  16. Hierarchical statistical shape models of multiobject anatomical structures: application to brain MRI.

    Science.gov (United States)

    Cerrolaza, Juan J; Villanueva, Arantxa; Cabeza, Rafael

    2012-03-01

    The accurate segmentation of subcortical brain structures in magnetic resonance (MR) images is of crucial importance in the interdisciplinary field of medical imaging. Although statistical approaches such as active shape models (ASMs) have proven to be particularly useful in the modeling of multiobject shapes, they are inefficient when facing challenging problems. Based on the wavelet transform, the fully generic multiresolution framework presented in this paper allows us to decompose the interobject relationships into different levels of detail. The aim of this hierarchical decomposition is twofold: to efficiently characterize the relationships between objects and their particular localities. Experiments performed on an eight-object structure defined in axial cross sectional MR brain images show that the new hierarchical segmentation significantly improves the accuracy of the segmentation, and while it exhibits a remarkable robustness with respect to the size of the training set.

  17. Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ting; Kao, Joseph

    2016-11-08

    Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. The assembly kinetics of supramolecular nanocomposite in thin films is governed by the energetic cost arising from defects, the chain mobility, and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in approximately one minute. Moreover, the strong wavelength dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present invention opens a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films.

  18. Controlling Torque Distribution for Parallel Hybrid Vehicle Based on Hierarchical Structure Fuzzy Logic

    Institute of Scientific and Technical Information of China (English)

    HuangMiao-hua; JinGuo-dong

    2003-01-01

    The Hierarchical Structure Fuzzy Logic Control(HSFLC) strategies of torque distribute for Parallel Hybrid Electric Vehicle (PHEV) in the mocle of operation of the vehicle i. e. , acceleration, cruise, deceleration etc. have been studied. Using secondly developed the hybrid vehicle simulation tool ADVISOR, the dynamic model of PHEV has been set up by MATLAB/SIMULINK. The engine, motor as well as the battery characteristics have been studied. Simulation results show that the proposed hierarchical structured fuzzy logic control strategy is effective over the entire operating range of the vehicle in terms of fuel economy. Based on the analyses of the simulation results and driver's experiences, a fuzzy controller is designed and developed to control the torque distribution. The controller is evaluated via hardware-in-the-loop simulator (HILS). The results show that controller verify its value.

  19. Spatio-temporal map generalizations with the hierarchical Voronoi data structure

    DEFF Research Database (Denmark)

    Mioc, Darka; Anton, François; Gold, Christopher M.

    of map objects, together with their temporal and spatial adjacency relationships. In this paper, we present new solutions to the problems of spatio-temporal generalizations using the hierarchical Voronoi spatio-temporal data structure. The application of the hierarchical Voronoi data structure presented...... in this research is in spatio-temporal map generalization, which is needed for reasoning about dynamic aspects of the world, primarily about actions, events and processes. This provides an advance in the domain of map generalization as we are able to deal not only with the cartographic objects, but also...... implemented in commercial GIS systems. In this research, we used the Voronoi spatial data model for map generalizations. We were able to demonstrate that the map generalization does not affect only spatial objects (points, lines or polygons), but also the events corresponding to the creation and modification...

  20. UV-assisted capillary force lithography for engineering biomimetic multiscale hierarchical structures: From lotus leaf to gecko foot hairs

    KAUST Repository

    Jeong, Hoon Eui

    2009-01-01

    This feature article provides an overview of the recently developed two-step UV-assisted capillary force lithography and its application to fabricating well-defined micro/nanoscale hierarchical structures. This method utilizes an oxygen inhibition effect in the course of UV irradiation curing and a two-step moulding process, to form multiscale hierarchical or suspended nanobridge structures in a rapid and reproducible manner. After a brief description of the fabrication principles, several examples of the two-step UV-assisted moulding technique are presented. In addition, emerging applications of the multiscale hierarchical structures are briefly described. © The Royal Society of Chemistry 2009.

  1. The Relationship between Self-Leadership and Personality: A Comparison of Hierarchical Factor Structures

    OpenAIRE

    Jeffery D. Houghton

    2000-01-01

    This study examined the relationship between self-leadership and personality through an analysis and comparison of hierarchical factor structures. More specifically, this study examined the relationships between the self-leadership dimensions of behavior-focused strategies, natural reward strategies, and constructive thought strategies, and the personality dimensions of extraversion, emotional stability, and conscientiousness. The results of the study provide evidence that the self-leadershi...

  2. structSSI: Simultaneous and Selective Inference for Grouped or Hierarchically Structured Data

    Directory of Open Access Journals (Sweden)

    Kris Sankaran

    2014-09-01

    We briefly describe the group Benjamini-Hochberg and hierarchical false discovery rate procedures and then illustrate them using two examples, one a measure of ecological microbial abundances and the other a global temperature time series. For both procedures, we detail the steps associated with the analysis of these particular data sets, including establishing the dependence structures, performing the test, and interpreting the results. These steps are encapsulated by R functions, and we explain their applicability to general data sets.

  3. HIERARCHICAL STRUCTURE OF MAGNETOHYDRODYNAMIC TURBULENCE IN POSITION-POSITION-VELOCITY SPACE

    Energy Technology Data Exchange (ETDEWEB)

    Burkhart, Blakesley; Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, 475 N. Charter St., WI 53711 (United States); Goodman, Alyssa [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Rosolowsky, Erik [University of British Columbia, Okanagan Campus, 3333 University Way, Kelowna BC V1V 1V7 (Canada)

    2013-06-20

    Magnetohydrodynamic turbulence is able to create hierarchical structures in the interstellar medium (ISM) that are correlated on a wide range of scales via the energy cascade. We use hierarchical tree diagrams known as dendrograms to characterize structures in synthetic position-position-velocity (PPV) emission cubes of isothermal magnetohydrodynamic turbulence. We show that the structures and degree of hierarchy observed in PPV space are related to the presence of self-gravity and the global sonic and Alfvenic Mach numbers. Simulations with higher Alfvenic Mach number, self-gravity and supersonic flows display enhanced hierarchical structure. We observe a strong dependency on the sonic and Alfvenic Mach numbers and self-gravity when we apply the statistical moments (i.e., mean, variance, skewness, kurtosis) to the leaf and node distribution of the dendrogram. Simulations with self-gravity, larger magnetic field and higher sonic Mach number have dendrogram distributions with higher statistical moments. Application of the dendrogram to three-dimensional density cubes, also known as position-position-position (PPP) cubes, reveals that the dominant emission contours in PPP and PPV are related for supersonic gas but not for subsonic. We also explore the effects of smoothing, thermal broadening, and velocity resolution on the dendrograms in order to make our study more applicable to observational data. These results all point to hierarchical tree diagrams as being a promising additional tool for studying ISM turbulence and star forming regions for obtaining information on the degree of self-gravity, the Mach numbers and the complicated relationship between PPV and PPP data.

  4. A Hierarchical FEM approach for Simulation of Geometrical and Material induced Instability of Composite Structures

    DEFF Research Database (Denmark)

    Hansen, Anders L.; Lund, Erik; Pinho, Silvestre T.

    2009-01-01

    In this paper a hierarchical FE approach is utilized to simulate delamination in a composite plate loaded in uni-axial compression. Progressive delamination is modelled by use of cohesive interface elements that are automatically embedded. The non-linear problem is solved quasi-statically in which...... the interaction between material degradation and structural instability is solved iteratively. The effect of fibre bridging is studied numerically and in-plane failure is predicted using physically based failure criteria....

  5. GENETIC CONSEQUENCES OF SEED DISPERSAL IN THREE SYMPATRIC FOREST HERBS. I. HIERARCHICAL POPULATION-GENETIC STRUCTURE.

    Science.gov (United States)

    Williams, Charles F; Guries, Raymond P

    1994-06-01

    To examine the effects of seed dispersal on spatial genetic structure, we compare three sympatric species of forest herbs in the family Apiaceae whose fruits differ widely in morphological adaptations for animal-attached dispersal. Cryptotaenia canadensis has smooth fruits that are gravity dispersed, whereas Osmorhiza claytonii and Sanicula odorata fruits have appendages that facilitate their attachment to animals. The relative seed-dispersal ability among species, measured as their ability to remain attached to mammal fur, is ranked Sanicula > Osmorhiza > Cryptotaenia. We use a nested hierarchical sampling design to analyze genetic structure at spatial scales ranging from a few meters to hundreds of kilometers. Genetic differentiation among population subdivisions, estimated by average genetic distance and hierarchical F-statistics, has an inverse relationship with dispersal ability such that Cryptotaenia > Osmorhiza > Sanicula. In each species, genetic differentiation increases with distance among population subdivisions. Stochastic variation in gene flow, arising from seed dispersal by attachment to animals, may partly explain the weak relationship between pairwise spatial and genetic distance among populations and heterogeneity in estimates of single locus F-statistics. A hierarchical island model of gene flow is invoked to describe the effects of seed dispersal on population genetic structure. Seed dispersal is the predominant factor affecting variation in gene flow among these ecologically similar, taxonomically related species. © 1994 The Society for the Study of Evolution.

  6. Inferring a district-based hierarchical structure of social contacts from census data.

    Directory of Open Access Journals (Sweden)

    Z Yu

    Full Text Available Researchers have recently paid attention to social contact patterns among individuals due to their useful applications in such areas as epidemic evaluation and control, public health decisions, chronic disease research and social network research. Although some studies have estimated social contact patterns from social networks and surveys, few have considered how to infer the hierarchical structure of social contacts directly from census data. In this paper, we focus on inferring an individual's social contact patterns from detailed census data, and generate various types of social contact patterns such as hierarchical-district-structure-based, cross-district and age-district-based patterns. We evaluate newly generated contact patterns derived from detailed 2011 Hong Kong census data by incorporating them into a model and simulation of the 2009 Hong Kong H1N1 epidemic. We then compare the newly generated social contact patterns with the mixing patterns that are often used in the literature, and draw the following conclusions. First, the generation of social contact patterns based on a hierarchical district structure allows for simulations at different district levels. Second, the newly generated social contact patterns reflect individuals social contacts. Third, the newly generated social contact patterns improve the accuracy of the SEIR-based epidemic model.

  7. On Hierarchical Extensions of Large-Scale 4-regular Grid Network Structures

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Patel, A.; Knudsen, Thomas Phillip

    It is studied how the introduction of ordered hierarchies in 4-regular grid network structures decreses distances remarkably, while at the same time allowing for simple topological routing schemes. Both meshes and tori are considered; in both cases non-hierarchical structures have power law......, and it is shown that while they allow for more flexibility in design and construction of structures supporting topological routing, their performances are comparable to the performance of the perfect square mesh. Finally suggestions for further research within the field are given....

  8. On Hierarchical Extensions of Large-Scale 4-regular Grid Network Structures

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Patel, A.; Knudsen, Thomas Phillip

    2004-01-01

    It is studied how the introduction of ordered hierarchies in 4-regular grid network structures decreases distances remarkably, while at the same time allowing for simple topological routing schemes. Both meshes and tori are considered; in both cases non-hierarchical structures have power law......, and it is shown that while they allow for more flexibility in design and construction of structures supporting topological routing, their performances are comparable to the performance of the perfect square mesh. Finally suggestions for further research within the field are given....

  9. Large area micro-/nano-structuring using direct laser interference patterning

    Science.gov (United States)

    Lasagni, Andrés. F.; Kunze, Tim; Bieda, Matthias; Günther, Denise; Gärtner, Anne; Lang, Valentin; Rank, Andreas; Roch, Teja

    2016-03-01

    Smart surfaces are a source of innovation in the 21st Century. Potential applications can be found in a wide range of fields where improved optical, mechanical or biological properties can enhance the functions of products. In the last years, a method called Direct Laser Interference Patterning (DLIP) has demonstrated to be capable of fabricating a wide range of periodic surface patterns even with resolution at the nanometer and sub-micrometer scales. This article describes recent advances of the DLIP method to process 2D and 3D parts. Firstly, the possibility to fabricate periodic arrays on metallic substrates with sub-micrometer resolution is shown. After that, different concepts to process three dimensional parts are shown, including the use of Cartesian translational stages as well as an industrial robot arm. Finally, some application examples are described.

  10. MICRO/NANO-STRUCTURAL EXAMINATION AND FISSION PRODUCT IDENTIFICATION IN NEUTRON IRRADIATED AGR-1 TRISO FUEL

    Energy Technology Data Exchange (ETDEWEB)

    van Rooyen, I. J.; Lillo, T. M.; Wen, H. M.; Hill, C. M.; Holesinger, T. G.; Wu, Y. Q.; Aguiara, J. A.

    2016-11-01

    Advanced microscopic and microanalysis techniques were developed and applied to study irradiation effects and fission product behavior in selected low-enriched uranium oxide/uranium carbide TRISO-coated particles from fuel compacts in six capsules irradiated to burnups of 11.2 to 19.6% FIMA. Although no TRISO coating failures were detected during the irradiation, the fraction of Ag-110m retained in individual particles often varied considerably within a single compact and at the capsule level. At the capsule level Ag-110m release fractions ranged from 1.2 to 38% and within a single compact, silver release from individual particles often spanned a range that extended from 100% retention to nearly 100% release. In this paper, selected irradiated particles from Baseline, Variant 1 and Variant 3 type fueled TRISO coated particles were examined using Scanning Electron Microscopy, Atom Probe Tomography; Electron Energy Loss Spectroscopy; Precession Electron Diffraction, Transmission Electron Microscopy, Scanning Transmission Electron Microscopy (STEM), High Resolution Electron Microscopy (HRTEM) examinations and Electron Probe Micro-Analyzer. Particle selection in this study allowed for comparison of the fission product distribution with Ag retention, fuel type and irradiation level. Nano sized Ag-containing features were predominantly identified in SiC grain boundaries and/or triple points in contrast with only two sitings of Ag inside a SiC grain in two different compacts (Baseline and Variant 3 fueled compacts). STEM and HRTEM analysis showed evidence of Ag and Pd co-existence in some cases and it was found that fission product precipitates can consist of multiple or single phases. STEM analysis also showed differences in precipitate compositions between Baseline and Variant 3 fuels. A higher density of fission product precipitate clusters were identified in the SiC layer in particles from the Variant 3 compact compared with the Variant 1 compact. Trend analysis shows precipitates were randomly distributed along the perimeter of the IPyC-SiC interlayer but only weakly associated with kernel protrusion and buffer fractures. There has been no evidence that the general release of silver is related to cracks or significant degradation of the microstructure. The results presented in this paper provide new insights to Ag transport mechanism(s) in intact SiC layer of TRISO coated particles.

  11. Micro/nanoscale continuous printing: direct-writing of wavy micro/nano structures via electrospinning

    Science.gov (United States)

    Fang, Feiyu; Du, Zefeng; Zeng, Jun; Zhu, Ziming; Chen, Xin; Chen, Xindu; Lv, Yuanjun; Wang, Han

    2015-07-01

    Micro/nanofibers that are created by direct-writing using an electrospinning (ES) technique have aroused much recent attention, owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW) process was developed to directly write wavy micro/nanostructures suitable for the fabrication of micro/nanoscale devices. The low voltage WDW technique is anticipated to be useful for a broad range of applications including flexible/stretchable electronics, micro optoelectronics, nano-antennas, microelectromechanical systems (MEMS), and biomedical engineering.

  12. About Hierarchical XML Structures, Replacement of Relational Data Structures in Construction and Implementation of ERP Systems

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The projects essential objective is to develop a new ERP system, of homogeneous nature, based on XML structures, as a possible replacement for classic ERP systems. The criteria that guide the objective definition are modularity, portability and Web connectivity. This objective is connected to a series of secondary objectives, considering that the technological approach will be filtered through the economic, social and legislative environment for a validation-by-context study. Statistics and cybernetics are to be used for simulation purposes. The homogeneous approach is meant to provide strong modularity and portability, in relation with the n-tier principles, but the main advantage of the model is its opening to the semantic Web, based on a Small enterprise ontology defined with XML-driven languages. Shockwave solutions will be used for implementing client-oriented hypermedia elements and an XML Gate will be de-fined between black box modules, for a clear separation with obvious advantages. Security and the XMLTP project will be an important issue for XML transfers due to the conflict between the open architecture of the Web, the readability of XML data and the privacy elements which have to be preserved within a business environment. The projects finality is oriented on small business but the semantic Web perspective and the surprising new conflict between hierarchical/network data structures and relational ones will certainly widen its scope. The proposed model is meant to fulfill the IT compatibility requirements of the European environment, defined as a knowledge society. The paper is a brief of the contributions of the team re-search at the project type A applied to CNCSIS "Research on the Role of XML in Building Extensible and Homogeneous ERP Systems".

  13. Synthesis and characterization of branched yttrium hydroxide fluoride microcrystals with hierarchical tubular structure

    Institute of Scientific and Technical Information of China (English)

    TIAN Li; JIANG Wentao; SUN Qiliang; LIU Jin

    2012-01-01

    Hexagonal yttrium hydroxide fluoride microcrystals were prepared by a two-step hydrothermal route using yttrium nitrate,sodium hydroxide and sodium fluoride as raw materials to react in propanetriol solvent.The samples were characterized by powder X-ray diffraction (XRD),energy dispersive spectrum (EDS),scanning electron microscopy (SEM),transmission electron microscopy (TEM),Fourier transform infrared spectroscopy (FT-IR),thermogravimetre and differential-thermogravimetric analysis (TG-DTA),which revealed that Y(OH)2.14F0.86 microcrystals were multi-branched and that the branches of Y(OH)2.14F0.86 microcrystals were composed of hierarchical tubes.This novel multi-branched and intriguing hierarchical tubular structure of yttrium hydroxide fluoride maybe has a potential application in photoelectric crystals.The formation of branched Y(OH)2.14F0.86 microcrystals with hierarchical tubular structure were due to the substitution reaction and Oswald ripening.

  14. Identifying overlapping and hierarchical thematic structures in networks of scholarly papers: a comparison of three approaches.

    Science.gov (United States)

    Havemann, Frank; Gläser, Jochen; Heinz, Michael; Struck, Alexander

    2012-01-01

    The aim of this paper is to introduce and assess three algorithms for the identification of overlapping thematic structures in networks of papers. We implemented three recently proposed approaches to the identification of overlapping and hierarchical substructures in graphs and applied the corresponding algorithms to a network of 492 information-science papers coupled via their cited sources. The thematic substructures obtained and overlaps produced by the three hierarchical cluster algorithms were compared to a content-based categorisation, which we based on the interpretation of titles, abstracts, and keywords. We defined sets of papers dealing with three topics located on different levels of aggregation: h-index, webometrics, and bibliometrics. We identified these topics with branches in the dendrograms produced by the three cluster algorithms and compared the overlapping topics they detected with one another and with the three predefined paper sets. We discuss the advantages and drawbacks of applying the three approaches to paper networks in research fields.

  15. Identifying overlapping and hierarchical thematic structures in networks of scholarly papers: a comparison of three approaches.

    Directory of Open Access Journals (Sweden)

    Frank Havemann

    Full Text Available The aim of this paper is to introduce and assess three algorithms for the identification of overlapping thematic structures in networks of papers. We implemented three recently proposed approaches to the identification of overlapping and hierarchical substructures in graphs and applied the corresponding algorithms to a network of 492 information-science papers coupled via their cited sources. The thematic substructures obtained and overlaps produced by the three hierarchical cluster algorithms were compared to a content-based categorisation, which we based on the interpretation of titles, abstracts, and keywords. We defined sets of papers dealing with three topics located on different levels of aggregation: h-index, webometrics, and bibliometrics. We identified these topics with branches in the dendrograms produced by the three cluster algorithms and compared the overlapping topics they detected with one another and with the three predefined paper sets. We discuss the advantages and drawbacks of applying the three approaches to paper networks in research fields.

  16. Chiral acidic amino acids induce chiral hierarchical structure in calcium carbonate

    Science.gov (United States)

    Jiang, Wenge; Pacella, Michael S.; Athanasiadou, Dimitra; Nelea, Valentin; Vali, Hojatollah; Hazen, Robert M.; Gray, Jeffrey J.; McKee, Marc D.

    2017-04-01

    Chirality is ubiquitous in biology, including in biomineralization, where it is found in many hardened structures of invertebrate marine and terrestrial organisms (for example, spiralling gastropod shells). Here we show that chiral, hierarchically organized architectures for calcium carbonate (vaterite) can be controlled simply by adding chiral acidic amino acids (Asp and Glu). Chiral, vaterite toroidal suprastructure having a `right-handed' (counterclockwise) spiralling morphology is induced by L-enantiomers of Asp and Glu, whereas `left-handed' (clockwise) morphology is induced by D-enantiomers, and sequentially switching between amino-acid enantiomers causes a switch in chirality. Nanoparticle tilting after binding of chiral amino acids is proposed as a chiral growth mechanism, where a `mother' subunit nanoparticle spawns a slightly tilted, consequential `daughter' nanoparticle, which by amplification over various length scales creates oriented mineral platelets and chiral vaterite suprastructures. These findings suggest a molecular mechanism for how biomineralization-related enantiomers might exert hierarchical control to form extended chiral suprastructures.

  17. Hierarchically Structured Graphene Coupled Microporous Organic Polymers for Superior CO2 Capture.

    Science.gov (United States)

    Liu, Fa-Qian; Wang, Li-Li; Li, Guo-Hua; Li, Wei; Li, Chao-Qin

    2017-10-04

    Hierarchically porous materials containing interconnected macro-/meso-/micropores are promising candidates for energy storage, catalysis, and gas separation. Here, we present an effective approach for synthesizing three-dimensional (3D) sulfonated graphene coupled microporous organic polymers (SG-MOPs). The resulting SG-MOPs possess uniform macropores with an average size of ca. 350 nm, abundant mesopores, and micropores with an average size of ca. 0.6 nm. The SG-supported adsorbents exhibit a high nitrogen content (more than 38.1 wt %), high adsorption capacity (up to 3.37 mmol CO2 g(-1)), high CO2/N2 selectivity from 42 to 51, moderate heat of adsorption, as well as good stability because of the hierarchical porous structure and excellent thermal conductivity of the SG scaffold. Thus, these nitrogen-enriched adsorbents allow the overall CO2 capture process to be promising and sustainable.

  18. Facile method for preparing superoleophobic surfaces with hierarchical microcubic/nanowire structures

    Science.gov (United States)

    Kwak, Wonshik; Hwang, Woonbong

    2016-02-01

    To facilitate the fabrication of superoleophobic surfaces having hierarchical microcubic/nanowire structures (HMNS), even for low surface tension liquids including octane (surface tension = 21.1 mN m-1), and to understand the influences of surface structures on the oleophobicity, we developed a convenient method to achieve superoleophobic surfaces on aluminum substrates using chemical acid etching, anodization and fluorination treatment. The liquid repellency of the structured surface was validated through observable experimental results the contact and sliding angle measurements. The etching condition required to ensure high surface roughness was established, and an optimal anodizing condition was determined, as a critical parameter in building the superoleophobicity. The microcubic structures formed by acid etching are essential for achieving the formation of the hierarchical structure, and therefore, the nanowire structures formed by anodization lead to an enhancement of the superoleophobicity for low surface tension liquids. Under optimized morphology by microcubic/nanowire structures with fluorination treatment, the contact angle over 150° and the sliding angle less than 10° are achieved even for octane.

  19. Spatial Object Aggregation Based on Data Structure,Local Triangulation and Hierarchical Analyzing Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper focuses on the methods and process of spatial aggregation based on semantic and geometric characteristics of spatial objects and relations among the objects with the help of spatial data structure (Formal Data Structure),the Local Constrained Delaunay Triangulations and semantic hierarchy.The adjacent relation among connected objects and unconnected objects has been studied through constrained triangle as elementary processing unit in aggregation operation.The hierarchical semantic analytical matrix is given for analyzing the similarity between objects types and between objects.Several different cases of aggregation have been presented in this paper.

  20. Hierarchically structured carbonaceous foams generation and their use as electrochemical energy storage devices

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Nicolas [Centre de Recherche Paul Pascal, Pessac (France); Institut des Sciences Moleculaires, Talence (France); Prabaharan, Savari R.S.; Morcrette, Mathieu [Laboratoire de Reactivite et de Chimie des Solides, Amiens (France); Pecastaing, Gilles [Laboratoire de Chimie des Polymeres Organiques, Pessac (France); Birot, Marc; Deleuze, Herve [Institut des Sciences Moleculaires, Talence (France); Backov, Renal [Centre de Recherche Paul Pascal, Pessac (France)

    2010-07-01

    Hierarchically structured carbonaceous foams with a high control over macro-meso-microporous structures have been synthesized, using silica as inorganic exotemplate and phenolic resin as carbon precursor. These monolithic foams have been thoroughly characterized over all length scales. The applications of this new series of macrocellular carbonaceous monoliths as negative electrodes for Lithium-ion batteries devices (stable capacity of 200 mAh.g{sup -1}, during 50 cycles) and electrochemical capacitors (specific capacitance of 30 F.g{sup -1} at a scan rate of 10 mV.s{sup -1}) have been checked and will be discussed. (orig.)

  1. Fabrication of semi-transparent superoleophobic thin film from fabrics and nanoparticle-based hierarchical structure

    Directory of Open Access Journals (Sweden)

    Nishizawa S.

    2013-08-01

    Full Text Available Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain resistant and antifouling materials, and microfluidics among others. Transparency is also desired with superhydrophobicity for their numerous applications; however transparency and oleophobicity are almost incompatible relationship with each other in the point of surface structure. Because oleophobicity required rougher structure at nano-micro scale than hydrophobicity, and these rough structure brings light scattering. So far, there is very few report of the compatible of transparency and superoleophobicity. In this report, we proposed the see-through type fabrics using the nanoparticle-based hierarchical structure thin film for improving both of oleophobicity and transparency. The vacant space between fibrils of fabrics has two important roles: the one is to through the light, another one is to introduce air layer to realize Cassie state of liquid droplet on thin film. To realize the low surface energy and nanoscale rough structure surface on fibrils, we used the spray method with perfluoroalkyl methacrylic copolymer (PMC, silica nano particles and volatile solvent. From the SEM image, the hierarchical structures of nanoparticle were formed uniformly on the fabrics. The transparency of thin film obtained was approximately 61% and the change of transparency between pre-coated fabrics and coated was 11%. From investigation of the surface wettability, the contact angles of oils (rapeseed oil and hexadecane and water droplet on the fabricated film were over 150 degree.

  2. Hierarchical assembly may be a way to make large information-rich structures

    CERN Document Server

    Whitelam, Stephen

    2015-01-01

    Self-assembly in the laboratory can now yield `information-rich' nanostructures in which each component is of a distinct type and has a defined spatial position. Ensuring the thermodynamic stability of such structures requires inter-component interaction energies to increase logarithmically with structure size, in order to counter the entropy gained upon mixing component types in solution. However, self-assembly in the presence of strong interactions results in general in kinetic trapping, so suggesting a limit to the size of an (equilibrium) structure that can be self-assembled from distinguishable components. Here we study numerically a two-dimensional hierarchical assembly scheme already considered in experiment. We show that this scheme is immune to the kinetic traps associated with strong `native' interactions (interactions designed to stabilize the intended structure), and so, in principle, offers a way to make large information-rich structures. In this scheme the size of an assembled structure scales e...

  3. The type I error rate for in vivo Comet assay data when the hierarchical structure is disregarded

    DEFF Research Database (Denmark)

    Hansen, Merete Kjær; Kulahci, Murat

    The Comet assay is a sensitive technique for detection of DNA strand breaks. The experimental design of in vivo Comet assay studies are often hierarchically structured, which should be reWected in the statistical analysis. However, the hierarchical structure sometimes seems to be disregarded, and...... the exposition of the statistical methodology and to suitably account for the hierarchical structure of Comet assay data whenever present.......The Comet assay is a sensitive technique for detection of DNA strand breaks. The experimental design of in vivo Comet assay studies are often hierarchically structured, which should be reWected in the statistical analysis. However, the hierarchical structure sometimes seems to be disregarded......, and this imposes considerable impact on the type I error rate. This study aims to demonstrate the implications that result from disregarding the hierarchical structure. DiUerent combinations of the factor levels as they appear in a literature study give type I error rates up to 0.51 and for all combinations...

  4. Neural mechanisms underlying the computation of hierarchical tree structures in mathematics.

    Directory of Open Access Journals (Sweden)

    Tomoya Nakai

    Full Text Available Whether mathematical and linguistic processes share the same neural mechanisms has been a matter of controversy. By examining various sentence structures, we recently demonstrated that activations in the left inferior frontal gyrus (L. IFG and left supramarginal gyrus (L. SMG were modulated by the Degree of Merger (DoM, a measure for the complexity of tree structures. In the present study, we hypothesize that the DoM is also critical in mathematical calculations, and clarify whether the DoM in the hierarchical tree structures modulates activations in these regions. We tested an arithmetic task that involved linear and quadratic sequences with recursive computation. Using functional magnetic resonance imaging, we found significant activation in the L. IFG, L. SMG, bilateral intraparietal sulcus (IPS, and precuneus selectively among the tested conditions. We also confirmed that activations in the L. IFG and L. SMG were free from memory-related factors, and that activations in the bilateral IPS and precuneus were independent from other possible factors. Moreover, by fitting parametric models of eight factors, we found that the model of DoM in the hierarchical tree structures was the best to explain the modulation of activations in these five regions. Using dynamic causal modeling, we showed that the model with a modulatory effect for the connection from the L. IPS to the L. IFG, and with driving inputs into the L. IFG, was highly probable. The intrinsic, i.e., task-independent, connection from the L. IFG to the L. IPS, as well as that from the L. IPS to the R. IPS, would provide a feedforward signal, together with negative feedback connections. We indicate that mathematics and language share the network of the L. IFG and L. IPS/SMG for the computation of hierarchical tree structures, and that mathematics recruits the additional network of the L. IPS and R. IPS.

  5. Neural mechanisms underlying the computation of hierarchical tree structures in mathematics.

    Science.gov (United States)

    Nakai, Tomoya; Sakai, Kuniyoshi L

    2014-01-01

    Whether mathematical and linguistic processes share the same neural mechanisms has been a matter of controversy. By examining various sentence structures, we recently demonstrated that activations in the left inferior frontal gyrus (L. IFG) and left supramarginal gyrus (L. SMG) were modulated by the Degree of Merger (DoM), a measure for the complexity of tree structures. In the present study, we hypothesize that the DoM is also critical in mathematical calculations, and clarify whether the DoM in the hierarchical tree structures modulates activations in these regions. We tested an arithmetic task that involved linear and quadratic sequences with recursive computation. Using functional magnetic resonance imaging, we found significant activation in the L. IFG, L. SMG, bilateral intraparietal sulcus (IPS), and precuneus selectively among the tested conditions. We also confirmed that activations in the L. IFG and L. SMG were free from memory-related factors, and that activations in the bilateral IPS and precuneus were independent from other possible factors. Moreover, by fitting parametric models of eight factors, we found that the model of DoM in the hierarchical tree structures was the best to explain the modulation of activations in these five regions. Using dynamic causal modeling, we showed that the model with a modulatory effect for the connection from the L. IPS to the L. IFG, and with driving inputs into the L. IFG, was highly probable. The intrinsic, i.e., task-independent, connection from the L. IFG to the L. IPS, as well as that from the L. IPS to the R. IPS, would provide a feedforward signal, together with negative feedback connections. We indicate that mathematics and language share the network of the L. IFG and L. IPS/SMG for the computation of hierarchical tree structures, and that mathematics recruits the additional network of the L. IPS and R. IPS.

  6. Neural Mechanisms Underlying the Computation of Hierarchical Tree Structures in Mathematics

    Science.gov (United States)

    Nakai, Tomoya; Sakai, Kuniyoshi L.

    2014-01-01

    Whether mathematical and linguistic processes share the same neural mechanisms has been a matter of controversy. By examining various sentence structures, we recently demonstrated that activations in the left inferior frontal gyrus (L. IFG) and left supramarginal gyrus (L. SMG) were modulated by the Degree of Merger (DoM), a measure for the complexity of tree structures. In the present study, we hypothesize that the DoM is also critical in mathematical calculations, and clarify whether the DoM in the hierarchical tree structures modulates activations in these regions. We tested an arithmetic task that involved linear and quadratic sequences with recursive computation. Using functional magnetic resonance imaging, we found significant activation in the L. IFG, L. SMG, bilateral intraparietal sulcus (IPS), and precuneus selectively among the tested conditions. We also confirmed that activations in the L. IFG and L. SMG were free from memory-related factors, and that activations in the bilateral IPS and precuneus were independent from other possible factors. Moreover, by fitting parametric models of eight factors, we found that the model of DoM in the hierarchical tree structures was the best to explain the modulation of activations in these five regions. Using dynamic causal modeling, we showed that the model with a modulatory effect for the connection from the L. IPS to the L. IFG, and with driving inputs into the L. IFG, was highly probable. The intrinsic, i.e., task-independent, connection from the L. IFG to the L. IPS, as well as that from the L. IPS to the R. IPS, would provide a feedforward signal, together with negative feedback connections. We indicate that mathematics and language share the network of the L. IFG and L. IPS/SMG for the computation of hierarchical tree structures, and that mathematics recruits the additional network of the L. IPS and R. IPS. PMID:25379713

  7. Synthesis and Characterization of Hierarchical Structured TiO2 Nanotubes and Their Photocatalytic Performance on Methyl Orange

    Directory of Open Access Journals (Sweden)

    Kai Liu

    2015-01-01

    Full Text Available Hierarchical structured TiO2 nanotubes were prepared by mechanical ball milling of highly ordered TiO2 nanotube arrays grown by electrochemical anodization of titanium foil. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, specific surface area analysis, UV-visible absorption spectroscopy, photocurrent measurement, photoluminescence spectra, electrochemical impedance spectra, and photocatalytic degradation test were applied to characterize the nanocomposites. Surface area increased as the milling time extended. After 5 h ball milling, TiO2 hierarchical nanotubes exhibited a corn-like shape and exhibited enhanced photoelectrochemical activity in comparison to commercial P25. The superior photocatalytic activity is suggested to be due to the combined advantages of high surface area of nanoparticles and rapid electron transfer as well as collection of the nanotubes in the hierarchical structure. The hierarchical structured TiO2 nanotubes could be applied into flexible applications on solar cells, sensors, and other photoelectrochemical devices.

  8. Frontoparietal Connectivity and Hierarchical Structure of the Brain’s Functional Network during Sleep

    Directory of Open Access Journals (Sweden)

    Victor I Spoormaker

    2012-05-01

    Full Text Available Frontal and parietal regions are associated with some of the most complex cognitive functions, and several frontoparietal resting-state networks can be observed in wakefulness. We used functional magnetic resonance imaging (fMRI data acquired in polysomnographically validated wakefulness, light sleep and slow-wave sleep to examine the hierarchical structure of a low-frequency functional brain network, and to examine whether frontoparietal connectivity would disintegrate in sleep. Whole-brain analyses with hierarchical cluster analysis on predefined atlases were performed, as well as regression of inferior parietal lobules seeds against all voxels in the brain, and an evaluation of the integrity of voxel time-courses in subcortical regions-of-interest. We observed that frontoparietal functional connectivity disintegrated in sleep stage 1 and was absent in deeper sleep stages. Slow-wave sleep was characterized by strong hierarchical clustering of local submodules. Frontoparietal connectivity between inferior parietal lobules and superior medial and right frontal gyrus was lower in sleep stages than in wakefulness. Moreover, thalamus voxels showed maintained integrity in sleep stage 1, making intrathalamic desynchronization an unlikely source of reduced thalamocortical connectivity in this sleep stage. Our data suggest a transition from a globally integrated functional brain network in wakefulness to a disintegrated network consisting of local submodules in slow-wave sleep, in which frontoparietal inter-modular nodes may play a crucial role, possibly in combination with the thalamus.

  9. Hierarchical system for autonomous sensing-healing of delamination in large-scale composite structures

    Science.gov (United States)

    Minakuchi, Shu; Sun, Denghao; Takeda, Nobuo

    2014-10-01

    This study combines our hierarchical fiber-optic-based delamination detection system with a microvascular self-healing material to develop the first autonomous sensing-healing system applicable to large-scale composite structures. In this combined system, embedded vascular modules are connected through check valves to a surface-mounted supply tube of a pressurized healing agent while fiber-optic-based sensors monitor the internal pressure of these vascular modules. When delamination occurs, the healing agent flows into the vascular modules breached by the delamination and infiltrates the damage for healing. At the same time, the pressure sensors identify the damaged modules by detecting internal pressure changes. This paper begins by describing the basic concept of the combined system and by discussing the advantages that arise from its hierarchical nature. The feasibility of the system is then confirmed through delamination infiltration tests. Finally, the hierarchical system is validated in a plate specimen by focusing on the detection and infiltration of the damage. Its self-diagnostic function is also demonstrated.

  10. Category breadth and hierarchical structure in personality: studies of asymmetries in judgments of trait implications.

    Science.gov (United States)

    Hampson, S E; John, O P; Goldberg, L R

    1986-07-01

    Trait breadth and hierarchical organization are central structural principles in personality theory and research. We assume that personality traits serve as categories of behavioral events, and we define the breadth of traits as the diversity of their behavioral manifestations. We show that trait breadth can be measured reliably both by ratings and by direct comparisons within trait pairs. We assess the hierarchical relations between traits differing in breadth, using a task in which subjects select the most meaningful of two statements, such as "To be talkative is a way of being extroverted" versus "To be extroverted is a way of being talkative." The extent of asymmetry in the choices of the subject sample provides an index of the degree of class inclusion. In four studies, we demonstrate that the size of the asymmetry effect is highly predictable from differences in trait breadth, even when the effects of social desirability, familiarity, and meaningfulness are controlled. Moreover, we replicate these findings in two cultural contexts, and even at the level of individual subjects. The availability of traits at different hierarchical levels requires personality psychologists to make an explicit choice about level of abstraction, especially when studying behavioral consistency. We discuss the prospect for identifying a generally preferred or "basic" level of personality description.

  11. Structural and photovoltaic characteristics of hierarchical ZnO nanostructures electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, Muhammad, E-mail: saleem.malikape@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, Chongqing University, Chongqing 400044 (China); Fang, L. [Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, Chongqing University, Chongqing 400044 (China); Shaukat, Saleem F.; Ahmad, M. Ashfaq [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Raza, Rizwan, E-mail: razahussaini786@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Akhtar, Majid Niaz; Jamil, Ayesha; Aslam, Samia [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Abbas, Ghazanfar [Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

    2015-04-15

    Highlights: • Hierarchically ZnO nanostructures electrodes were grown using hot plate magnetic stirring at different growth reaction temperature. • We have investigated the effect of working temperature of 160°, 170°, 180°, and 190° on the growth mechanism of nanospheres and on the power conversion efficiency of DSSCs. • ZnO nanospheres with perfect aggregation show superior power conversion efficiency of 1.24% which is about 83% higher than nanoparticles DSSC. • An obvious vogue is that the overall power conversion efficiency decreases as the degree of the spherical aggregation is gradually destroyed. - Abstract: Structural and photovoltaic characteristics of hierarchical ZnO nanostructures solar cell have been studied in relation to growth reaction temperature. It is found that the hierarchical ZnO nanostructures network to act not only as large surface area substrates but also as a transport medium for electrons injected from the dye molecules. The incident photon-to-current conversion efficiency is decreased by increasing the growth reaction temperature of ZnO electrodes. The best conversion efficiency of a 0.25 cm{sup 2} cell is measured to be 1.24% under 100 mW cm{sup −2} irradiation.

  12. Data with hierarchical structure: impact of intraclass correlation and sample size on type-I error.

    Science.gov (United States)

    Musca, Serban C; Kamiejski, Rodolphe; Nugier, Armelle; Méot, Alain; Er-Rafiy, Abdelatif; Brauer, Markus

    2011-01-01

    Least squares analyses (e.g., ANOVAs, linear regressions) of hierarchical data leads to Type-I error rates that depart severely from the nominal Type-I error rate assumed. Thus, when least squares methods are used to analyze hierarchical data coming from designs in which some groups are assigned to the treatment condition, and others to the control condition (i.e., the widely used "groups nested under treatment" experimental design), the Type-I error rate is seriously inflated, leading too often to the incorrect rejection of the null hypothesis (i.e., the incorrect conclusion of an effect of the treatment). To highlight the severity of the problem, we present simulations showing how the Type-I error rate is affected under different conditions of intraclass correlation and sample size. For all simulations the Type-I error rate after application of the popular Kish (1965) correction is also considered, and the limitations of this correction technique discussed. We conclude with suggestions on how one should collect and analyze data bearing a hierarchical structure.

  13. Data with hierarchical structure: impact of intraclass correlation and sample size on Type-I error

    Directory of Open Access Journals (Sweden)

    Serban C Musca

    2011-04-01

    Full Text Available Least squares analyses (e.g., ANOVAs, linear regressions of hierarchical data leads to Type-I error rates that depart severely from the nominal Type-I error rate assumed. Thus, when least squares methods are used to analyze hierarchical data coming from designs in which some groups are assigned to the treatment condition, and others to the control condition (i.e., the widely used "groups nested under treatment" experimental design, the Type-I error rate is seriously inflated, leading too often to the incorrect rejection of the null hypothesis (i.e., the incorrect conclusion of an effect of the treatment. To highlight the severity of the problem, we present simulations showing how the Type-I error rate is affected under different conditions of intraclass correlation and sample size. For all simulations the Type-I error rate after application of the popular Kish (1965 correction is also considered, and the limitations of this correction technique discussed. We conclude with suggestions on how one should collect and analyze data bearing a hierarchical structure.

  14. The structural color of red rose petals and their duplicates.

    Science.gov (United States)

    Feng, Lin; Zhang, Yanan; Li, Mingzhu; Zheng, Yongmei; Shen, Weizhi; Jiang, Lei

    2010-09-21

    The observation of the surface of a red rose petal indicates that there are micropapillae on the surface and many nanofolders exist on each papilla. Here, much tinier nanorods with periodic pattern on the nanofolders can be seen by in situ atomic force microscopy (AFM). Angle-resolved UV-vis spectral measurement and reflectance UV-vis spectra by immersion red rose petal in solvents with different refractive indices demonstrate that such periodic nanostructures can induce structural color. The combination of structural color, driven by the nanostructures, and chemical color, driven by pigments, provide flowers bright color and special functions for human and animals' visual system. Biomimic polymer films, that fabricated by duplicating the petal's hierarchical micro/nano structures, exhibit only structural color by UV-vis spectra since there is no pigment introduced.

  15. Hierarchical structures of correlations networks among Turkey’s exports and imports by currencies

    Science.gov (United States)

    Kocakaplan, Yusuf; Deviren, Bayram; Keskin, Mustafa

    2012-12-01

    We have examined the hierarchical structures of correlations networks among Turkey’s exports and imports by currencies for the 1996-2010 periods, using the concept of a minimal spanning tree (MST) and hierarchical tree (HT) which depend on the concept of ultrametricity. These trees are useful tools for understanding and detecting the global structure, taxonomy and hierarchy in financial markets. We derived a hierarchical organization and build the MSTs and HTs during the 1996-2001 and 2002-2010 periods. The reason for studying two different sub-periods, namely 1996-2001 and 2002-2010, is that the Euro (EUR) came into use in 2001, and some countries have made their exports and imports with Turkey via the EUR since 2002, and in order to test various time-windows and observe temporal evolution. We have carried out bootstrap analysis to associate a value of the statistical reliability to the links of the MSTs and HTs. We have also used the average linkage cluster analysis (ALCA) to observe the cluster structure more clearly. Moreover, we have obtained the bidimensional minimal spanning tree (BMST) due to economic trade being a bidimensional problem. From the structural topologies of these trees, we have identified different clusters of currencies according to their proximity and economic ties. Our results show that some currencies are more important within the network, due to a tighter connection with other currencies. We have also found that the obtained currencies play a key role for Turkey’s exports and imports and have important implications for the design of portfolio and investment strategies.

  16. A study of hierarchical structure on South China industrial electricity-consumption correlation

    Science.gov (United States)

    Yao, Can-Zhong; Lin, Ji-Nan; Liu, Xiao-Feng

    2016-02-01

    Based on industrial electricity-consumption data of five southern provinces of China from 2005 to 2013, we study the industrial correlation mechanism with MST (minimal spanning tree) and HT (hierarchical tree) models. First, we comparatively analyze the industrial electricity-consumption correlation structure in pre-crisis and after-crisis period using MST model and Bootstrap technique of statistical reliability test of links. Results exhibit that all industrial electricity-consumption trees of five southern provinces of China in pre-crisis and after-crisis time are in formation of chain, and the "center-periphery structure" of those chain-like trees is consistent with industrial specialization in classical industrial chain theory. Additionally, the industrial structure of some provinces is reorganized and transferred in pre-crisis and after-crisis time. Further, the comparative analysis with hierarchical tree and Bootstrap technique demonstrates that as for both observations of GD and overall NF, the industrial electricity-consumption correlation is non-significant clustered in pre-crisis period, whereas it turns significant clustered in after-crisis time. Therefore we propose that in perspective of electricity-consumption, their industrial structures are directed to optimized organization and global correlation. Finally, the analysis of distance of HTs verifies that industrial reorganization and development may strengthen market integration, coordination and correlation of industrial production. Except GZ, other four provinces have a shorter distance of industrial electricity-consumption correlation in after-crisis period, revealing a better performance of regional specialization and integration.

  17. Research on a Diamond Tip Wear Mechanism in Atomic Force Microscope-based Micro/nano-machining

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The object is to investigate the wear of an atomic forcemicroscope (AFM) diamond tip when conducting micro/nano-machining on single crystal silicon surface. The experimental research and theoretical analysis were carried out on the worn tip in terms of wear rate, wear mechanism and the effect of the tip wear on micro-machining process. The wear rate was calculated as 1.7(10~10mm3/(N*m) by using a theoretical model combined with the experimental results. Through an integration of an AFM observation on the worn tip features with the FEM simulation of the stress distribution, in addition to the unit cutting force calculation on the AFM diamond tip, the wear mechanism of the AFM diamond tip was concluded as mainly chemical wear, and the wear process was also elaborated as well.

  18. QMRPF-UKF Master-Slave Filtering for the Attitude Determination of Micro-Nano Satellites Using Gyro and Magnetometer

    Directory of Open Access Journals (Sweden)

    Huijuan Zhang

    2010-11-01

    Full Text Available In this paper, the problem of estimating the attitude of a micro-nano satellite, obtaining geomagnetic field measurements via a three-axis magnetometer and obtaining angle rate via gyro, is considered. For this application, a QMRPF-UKF master-slave filtering method is proposed, which uses the QMRPF and UKF algorithms to estimate the rotation quaternion and the gyro bias parameters, respectively. The computational complexicity related to the particle filtering technique is eliminated by introducing a multiresolution approach that permits a significant reduction in the number of particles. This renders QMRPF-UKF master-slave filter computationally efficient and enables its implementation with a remarkably small number of particles. Simulation results by using QMRPF-UKF are given, which demonstrate the validity of the QMRPF-UKF nonlinear filter.

  19. Micro-and nano-structured conducting polymeric materials

    Institute of Scientific and Technical Information of China (English)

    LU Gewu; CHEN Feng'en; WU Xufeng; QU Liangti; ZHANG Jiaxin; SHI Gaoquan

    2005-01-01

    Conducting polymeric materials with micro-/nano-structures have potential applications in fabrication of various optical, electronic, sensing and electrochemical devices. This is mainly because these materials not only possess the characteristics of conducting polymers, but also have special functions based on their micro- or nano-structures. In this review, we summarize the recent work on "soft" and "hard" template-guided syntheses of micro-/nano-structured conducting polymers and open up the prospects of the main trends in this field.

  20. Hierarchical robot control structure and Newton's divided difference approach to robot path planning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A hierarchical robot control is proposed for robot soccer system. The Newton' s divided difference is utilized in robot path planning. This paper describes the problems encoutered, software design considerations, vision algorithm and controls of individual robots. The solutions.to the problems implemented are simple and di rect. It is observed that many of the ideas and solutions can be evolved based on simple theories and concepts. This paper focuses on software structure of multi-agent controls, vision algorithm and simple path planning method.

  1. Hierarchically structured lithium titanate for ultrafast charging in long-life high capacity batteries

    Science.gov (United States)

    Odziomek, Mateusz; Chaput, Frédéric; Rutkowska, Anna; Świerczek, Konrad; Olszewska, Danuta; Sitarz, Maciej; Lerouge, Frédéric; Parola, Stephane

    2017-05-01

    High-performance Li-ion batteries require materials with well-designed and controlled structures on nanometre and micrometre scales. Electrochemical properties can be enhanced by reducing crystallite size and by manipulating structure and morphology. Here we show a method for preparing hierarchically structured Li4Ti5O12 yielding nano- and microstructure well-suited for use in lithium-ion batteries. Scalable glycothermal synthesis yields well-crystallized primary 4-8 nm nanoparticles, assembled into porous secondary particles. X-ray photoelectron spectroscopy reveals presence of Ti+4 only; combined with chemical analysis showing lithium deficiency, this suggests oxygen non-stoichiometry. Electron microscopy confirms hierarchical morphology of the obtained material. Extended cycling tests in half cells demonstrates capacity of 170 mAh g-1 and no sign of capacity fading after 1,000 cycles at 50C rate (charging completed in 72 s). The particular combination of nanostructure, microstructure and non-stoichiometry for the prepared lithium titanate is believed to underlie the observed electrochemical performance of material.

  2. Hierarchical organization in the temporal structure of infant-direct speech and song.

    Science.gov (United States)

    Falk, Simone; Kello, Christopher T

    2017-06-01

    Caregivers alter the temporal structure of their utterances when talking and singing to infants compared with adult communication. The present study tested whether temporal variability in infant-directed registers serves to emphasize the hierarchical temporal structure of speech. Fifteen German-speaking mothers sang a play song and told a story to their 6-months-old infants, or to an adult. Recordings were analyzed using a recently developed method that determines the degree of nested clustering of temporal events in speech. Events were defined as peaks in the amplitude envelope, and clusters of various sizes related to periods of acoustic speech energy at varying timescales. Infant-directed speech and song clearly showed greater event clustering compared with adult-directed registers, at multiple timescales of hundreds of milliseconds to tens of seconds. We discuss the relation of this newly discovered acoustic property to temporal variability in linguistic units and its potential implications for parent-infant communication and infants learning the hierarchical structures of speech and language. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. The relationships between electricity consumption and GDP in Asian countries, using hierarchical structure methods

    Science.gov (United States)

    Kantar, Ersin; Keskin, Mustafa

    2013-11-01

    This study uses hierarchical structure methods (minimal spanning tree (MST) and hierarchical tree (HT)) to examine the relationship between energy consumption and economic growth in a sample of 30 Asian countries covering the period 1971-2008. These countries are categorized into four panels based on the World Bank income classification, namely high, upper middle, lower middle, and low income. In particular, we use the data of electricity consumption and real gross domestic product (GDP) per capita to detect the topological properties of the countries. We show a relationship between electricity consumption and economic growth by using the MST and HT. We also use the bootstrap technique to investigate a value of the statistical reliability to the links of the MST. Finally, we use a clustering linkage procedure in order to observe the cluster structure. The results of the structural topologies of these trees are as follows: (i) we identified different clusters of countries according to their geographical location and economic growth, (ii) we found a strong relationship between energy consumption and economic growth for all income groups considered in this study and (iii) the results are in good agreement with the causal relationship between electricity consumption and economic growth.

  4. Controllable synthesis of branched ZnO/Si nanowire arrays with hierarchical structure.

    Science.gov (United States)

    Huang, Shengli; Yang, Qianqian; Yu, Binbin; Li, Dingguo; Zhao, Ruisheng; Li, Shuping; Kang, Junyong

    2014-01-01

    A rational approach for creating branched ZnO/Si nanowire arrays with hierarchical structure was developed based on a combination of three simple and cost-effective synthesis pathways. The crucial procedure included growth of crystalline Si nanowire arrays as backbones by chemical etching of Si substrates, deposition of ZnO thin film as a seed layer by magnetron sputtering, and fabrication of ZnO nanowire arrays as branches by hydrothermal growth. The successful synthesis of ZnO/Si heterogeneous nanostructures was confirmed by morphologic, structural, and optical characterizations. The roles of key experimental parameters, such as the etchant solution, the substrate direction, and the seed layer on the hierarchical nanostructure formation, were systematically investigated. It was demonstrated that an etchant solution with an appropriate redox potential of the oxidant was crucial for a moderate etching speed to achieve a well-aligned Si nanowire array with solid and round surface. Meanwhile, the presence of gravity gradient was a key issue for the growth of branched ZnO nanowire arrays. The substrate should be placed vertically or facedown in contrast to the solution surface during the hydrothermal growth. Otherwise, only the condensation of the ZnO nanoparticles took place in a form of film on the substrate surface. The seed layer played another important role in the growth of ZnO nanowire arrays, as it provided nucleation sites and determined the growing direction and density of the nanowire arrays for reducing the thermodynamic barrier. The results of this study might provide insight on the synthesis of hierarchical three-dimensional nanostructure materials and offer an approach for the development of complex devices and advanced applications.

  5. SHIPS: Spectral Hierarchical clustering for the Inference of Population Structure in genetic studies.

    Science.gov (United States)

    Bouaziz, Matthieu; Paccard, Caroline; Guedj, Mickael; Ambroise, Christophe

    2012-01-01

    Inferring the structure of populations has many applications for genetic research. In addition to providing information for evolutionary studies, it can be used to account for the bias induced by population stratification in association studies. To this end, many algorithms have been proposed to cluster individuals into genetically homogeneous sub-populations. The parametric algorithms, such as Structure, are very popular but their underlying complexity and their high computational cost led to the development of faster parametric alternatives such as Admixture. Alternatives to these methods are the non-parametric approaches. Among this category, AWclust has proven efficient but fails to properly identify population structure for complex datasets. We present in this article a new clustering algorithm called Spectral Hierarchical clustering for the Inference of Population Structure (SHIPS), based on a divisive hierarchical clustering strategy, allowing a progressive investigation of population structure. This method takes genetic data as input to cluster individuals into homogeneous sub-populations and with the use of the gap statistic estimates the optimal number of such sub-populations. SHIPS was applied to a set of simulated discrete and admixed datasets and to real SNP datasets, that are data from the HapMap and Pan-Asian SNP consortium. The programs Structure, Admixture, AWclust and PCAclust were also investigated in a comparison study. SHIPS and the parametric approach Structure were the most accurate when applied to simulated datasets both in terms of individual assignments and estimation of the correct number of clusters. The analysis of the results on the real datasets highlighted that the clusterings of SHIPS were the more consistent with the population labels or those produced by the Admixture program. The performances of SHIPS when applied to SNP data, along with its relatively low computational cost and its ease of use make this method a promising

  6. Toughening mystery of natural rubber deciphered by double network incorporating hierarchical structures.

    Science.gov (United States)

    Zhou, Weiming; Li, Xiangyang; Lu, Jie; Huang, Ningdong; Chen, Liang; Qi, Zeming; Li, Liangbin; Liang, Haiyi

    2014-12-16

    As an indispensible material for modern society, natural rubber possesses peerless mechanical properties such as strength and toughness over its artificial analogues, which remains a mystery. Intensive experimental and theoretical investigations have revealed the self-enhancement of natural rubber due to strain-induced crystallization. However a rigorous model on the self-enhancement, elucidating natural rubber's extraordinary mechanical properties, is obscured by deficient understanding of the local hierarchical structure under strain. With spatially resolved synchrotron radiation micro-beam scanning X-ray diffraction we discover weak oscillation in distributions of strain-induced crystallinity around crack tip for stretched natural rubber film, demonstrating a soft-hard double network structure. The fracture energy enhancement factor obtained by utilizing the double network model indicates an enhancement of toughness by 3 orders. It's proposed that upon stretching spontaneously developed double network structures integrating hierarchy at multi length-scale in natural rubber play an essential role in its remarkable mechanical performance.

  7. How Are Researching and Reading Interwieved during Retrieval from Hierarchically Structured Documents?

    DEFF Research Database (Denmark)

    Hertzum, Morten; Lalmas, M.; Frøkjær, Erik

    2001-01-01

    Effective use of information retrieval systems requires that users know when to – temporarily – cease searching to do some reading and where to start reading. In hierarchically structured documents, users can to some extent interchange searching and reading by entering the text at different levels...... in the structure. Based on an experiment where 83 subjects solved 20 tasks each, we find that the subjects spend at least one third of their time reading, irrespective of whether the system they use offers browsing and/or querying. The subjects prefer reading the text in chunks that span multiple levels...... of the structure. As much as 21% of the tasks are solved by subjects who enter the text at a level above the texts containing the answer and rely on reading from there. In relation to queries, multi-level texts are used to extend hits with more detail or, occasionally, more context. Designers should consider how...

  8. 月桂酸修饰微/纳米二氧化钛及摩擦学性能研究%Tribological properties of TiO2 micro-nano particles modified by lauric acid

    Institute of Scientific and Technical Information of China (English)

    钱建华; 孙科; 刘琳; 邢锦娟

    2014-01-01

    利用月桂酸对金红石型微/纳米TiO2进行了有机表面改性。粒子采用了红外光谱( IR)、热分析( TG-DTA)、扫描电镜( SEM)等对表面改性前后的微/纳米TiO2结构进行了表征。红外光谱、热分析表明月桂酸是以化学键合的方式结合在微/纳米TiO2表面形成了包覆层。在四球摩擦磨损试验机上考察了产品作为添加剂在石蜡基础油中的抗磨减磨性能。试验结果表明,修饰后的微/纳米粒子具有优良的抗磨、减摩能力,同时分析了减摩机理。%The Rutile TiO2 micro nanoparticles were modified by Lauric acid in this paper.The structures of micro-nano TiO2 were characterized using Infrared spectroscopy ( IR) , Thermal analysis ( TG-DTA) , Scan-ning electron microscopy ( SEM) .The results show that lauric acid is chemically bonded in micro-nano TiO2 surface and forms a coating layer.The antiwear and anti-friction property of the product as an additive in paraf-fin base oil was investigated by a four-ball machine.The results illustrate that the modified nano-particulars have excellent anti-wear, anti-friction performance, and finally the friction mechanism is also analyzed.

  9. Self-assembly of hierarchically ordered structures in DNA nanotube systems

    Science.gov (United States)

    Glaser, Martin; Schnauß, Jörg; Tschirner, Teresa; Schmidt, B. U. Sebastian; Moebius-Winkler, Maximilian; Käs, Josef A.; Smith, David M.

    2016-05-01

    The self-assembly of molecular and macromolecular building blocks into organized patterns is a complex process found in diverse systems over a wide range of size and time scales. The formation of star- or aster-like configurations, for example, is a common characteristic in solutions of polymers or other molecules containing multi-scaled, hierarchical assembly processes. This is a recurring phenomenon in numerous pattern-forming systems ranging from cellular constructs to solutions of ferromagnetic colloids or synthetic plastics. To date, however, it has not been possible to systematically parameterize structural properties of the constituent components in order to study their influence on assembled states. Here, we circumvent this limitation by using DNA nanotubes with programmable mechanical properties as our basic building blocks. A small set of DNA oligonucleotides can be chosen to hybridize into micron-length DNA nanotubes with a well-defined circumference and stiffness. The self-assembly of these nanotubes to hierarchically ordered structures is driven by depletion forces caused by the presence of polyethylene glycol. This trait allowed us to investigate self-assembly effects while maintaining a complete decoupling of density, self-association or bundling strength, and stiffness of the nanotubes. Our findings show diverse ranges of emerging structures including heterogeneous networks, aster-like structures, and densely bundled needle-like structures, which compare to configurations found in many other systems. These show a strong dependence not only on concentration and bundling strength, but also on the underlying mechanical properties of the nanotubes. Similar network architectures to those caused by depletion forces in the low-density regime are obtained when an alternative hybridization-based bundling mechanism is employed to induce self-assembly in an isotropic network of pre-formed DNA nanotubes. This emphasizes the universal effect inevitable

  10. Friction and adhesion of hierarchical carbon nanotube structures for biomimetic dry adhesives: multiscale modeling.

    Science.gov (United States)

    Hu, Shihao; Jiang, Haodan; Xia, Zhenhai; Gao, Xiaosheng

    2010-09-01

    With unique hierarchical fibrillar structures on their feet, gecko lizards can walk on vertical walls or even ceilings. Recent experiments have shown that strong binding along the shear direction and easy lifting in the normal direction can be achieved by forming unidirectional carbon nanotube array with laterally distributed tips similar to gecko's feet. In this study, a multiscale modeling approach was developed to analyze friction and adhesion behaviors of this hierarchical fibrillar system. Vertically aligned carbon nanotube array with laterally distributed segments at the end was simulated by coarse grained molecular dynamics. The effects of the laterally distributed segments on friction and adhesion strengths were analyzed, and further adopted as cohesive laws used in finite element analysis at device scale. The results show that the laterally distributed segments play an essential role in achieving high force anisotropy between normal and shear directions in the adhesives. Finite element analysis reveals a new friction-enhanced adhesion mechanism of the carbon nanotube array, which also exists in gecko adhesive system. The multiscale modeling provides an approach to bridge the microlevel structures of the carbon nanotube array with its macrolevel adhesive behaviors, and the predictions from this modeling give an insight into the mechanisms of gecko-mimicking dry adhesives.

  11. Emergence of hierarchical structure mirroring linguistic composition in a recurrent neural network.

    Science.gov (United States)

    Hinoshita, Wataru; Arie, Hiroaki; Tani, Jun; Okuno, Hiroshi G; Ogata, Tetsuya

    2011-05-01

    We show that a Multiple Timescale Recurrent Neural Network (MTRNN) can acquire the capabilities to recognize, generate, and correct sentences by self-organizing in a way that mirrors the hierarchical structure of sentences: characters grouped into words, and words into sentences. The model can control which sentence to generate depending on its initial states (generation phase) and the initial states can be calculated from the target sentence (recognition phase). In an experiment, we trained our model over a set of unannotated sentences from an artificial language, represented as sequences of characters. Once trained, the model could recognize and generate grammatical sentences, even if they were not learned. Moreover, we found that our model could correct a few substitution errors in a sentence, and the correction performance was improved by adding the errors to the training sentences in each training iteration with a certain probability. An analysis of the neural activations in our model revealed that the MTRNN had self-organized, reflecting the hierarchical linguistic structure by taking advantage of the differences in timescale among its neurons: in particular, neurons that change the fastest represented "characters", those that change more slowly, "words", and those that change the slowest, "sentences".

  12. Hierarchical structures induce long-range dynamical correlations in written texts.

    Science.gov (United States)

    Alvarez-Lacalle, E; Dorow, B; Eckmann, J-P; Moses, E

    2006-05-23

    Thoughts and ideas are multidimensional and often concurrent, yet they can be expressed surprisingly well sequentially by the translation into language. This reduction of dimensions occurs naturally but requires memory and necessitates the existence of correlations, e.g., in written text. However, correlations in word appearance decay quickly, while previous observations of long-range correlations using random walk approaches yield little insight on memory or on semantic context. Instead, we study combinations of words that a reader is exposed to within a "window of attention," spanning about 100 words. We define a vector space of such word combinations by looking at words that co-occur within the window of attention, and analyze its structure. Singular value decomposition of the co-occurrence matrix identifies a basis whose vectors correspond to specific topics, or "concepts" that are relevant to the text. As the reader follows a text, the "vector of attention" traces out a trajectory of directions in this "concept space." We find that memory of the direction is retained over long times, forming power-law correlations. The appearance of power laws hints at the existence of an underlying hierarchical network. Indeed, imposing a hierarchy similar to that defined by volumes, chapters, paragraphs, etc. succeeds in creating correlations in a surrogate random text that are identical to those of the original text. We conclude that hierarchical structures in text serve to create long-range correlations, and use the reader's memory in reenacting some of the multidimensionality of the thoughts being expressed.

  13. The contribution of reinforcement sensitivity to the personality-psychopathology hierarchical structure in childhood and adolescence.

    Science.gov (United States)

    Slobodskaya, Helena R

    2016-11-01

    This study examined the contribution of reinforcement sensitivity to the hierarchical structure of child personality and common psychopathology in community samples of parent reports of children aged 2-18 (N = 968) and self-reports of adolescents aged 10-18 (N = 1,543) using the Inventory of Child Individual Differences-Short version (ICID-S), the Strengths and Difficulties Questionnaire (SDQ), and the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ). A joint higher-order factor analysis of the ICID-S and SDQ scales suggested a 4-factor solution; congruence coefficients indicated replicability of the factors across the 2 samples at all levels of the personality-psychopathology hierarchy. The canonical correlation analyses indicated that reinforcement sensitivity and personality-psychopathology dimensions shared much of their variance. The main contribution of reinforcement sensitivity was through opposing effects of reward and punishment sensitivities. The superordinate factors Beta and Internalizing were best predicted by reinforcement sensitivity, followed by the Externalizing and Positive personality factors. These findings provide evidence for consistency of the hierarchical structure of personality and common psychopathology across informants and highlight the role of reinforcement systems in the development of normal and abnormal patterns of behavior and affect. (PsycINFO Database Record

  14. Hierarchical assemblies of soft matters from polymers and liquid crystals on structured surfaces

    Science.gov (United States)

    Honglawan, Apiradee

    Hierarchical, multifunctional materials hold important keys to numerous advanced technologies, including electronics, optics, and medicine. This thesis encompasses generation of hierarchical structures with novel morphologies and functions through self-assembly directed by lithographically fabricated templates. Here, two soft materials, amphiphilic random copolymers of photopolymerized acryloyl chloride (ranPAC) and smectic-A liquid crystal (SmA-LC) molecule, 4'(5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecaflu-orododecyloxy)-biphenyl-4-carboxylic acid ethyl ester, are synthesized as model systems to investigate the governing principles at the topographic surface/interface. The ranPAC can self-organize into nanomicelles with high regularity and stability, typically not possible in random copolymer systems. The morphology can be controlled by the photopolymerization conditions and solvent; the crosslinked shell makes the micelles robust against drying and storage. Using SU-8 micropillar arrays with spatially controlled surface chemistry as templates, we construct hierarchical microporous structures with tunable pore size and symmetry (e.g. square array), and uncover a new evaporative assembly method. By functionalizing the ranPAC nanovesicles with cationic poly(ethyleneimines), we encapsulate the anticancer drug, doxorubicin hydrochloride, and mRNA at a high payload, which are delivered to HEK 293T cells in vitro at a low cytotoxicity level. SmA-LC are characterized by arrangement of molecules into thin layers with the long molecular axis parallel to the layer normal, forming a close-packed hexagonal array of topological defects known as focal conic domains (FCDs) in a thin film. Using a series of SU-8 micropillar arrays with different size, shape, height, and symmetry as topological templates, we investigate the epitaxial and hierarchical assemblies of FCDs; whether the system favors confinement or "pillar edge-pinning" depends on balance of the elastic energy

  15. Hierarchically structured self-supported latex films for flexible and semi-transparent electronics

    Energy Technology Data Exchange (ETDEWEB)

    Määttänen, Anni, E-mail: anni.maattanen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Ihalainen, Petri, E-mail: petri.ihalainen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Törngren, Björn, E-mail: bjorn.torngren@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Rosqvist, Emil, E-mail: emil.rosqvist@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Pesonen, Markus, E-mail: markus.pesonen@abo.fi [Physics, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland); Peltonen, Jouko, E-mail: jouko.peltonen@abo.fi [Laboratory of Physical Chemistry, Faculty of Science and Engineering, Center for Functional Materials, Åbo Akademi University, Porthaninkatu 3, 20500, Turku (Finland)

    2016-02-28

    Graphical abstract: - Highlights: • Transparent self-supported latex films were fabricated by a peel-off process. • Various template substrates were used for creating e.g. hierarchically structured latex films. • Ultra-thin and semi-transparent conductive gold electrodes were evaporated on the latex films.Electrochemical experiments were carried out to verify the applicability of the electrodes. - Abstract: Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV–vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH{sub 2}){sub 11}OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal

  16. 接触触发式三维微纳米探头%A Touch Trigger 3D Probe for Micro/Nano Measurement

    Institute of Scientific and Technical Information of China (English)

    李瑞君; 李心愿; 向萌; 程真英; 范光照

    2016-01-01

    To meet the requirement of high precision 3D measurement for MEMS devices, a new high precision touch trigger probe for micro-Nano/CMM is developed. Only one Quadrant Photo Diode (QPD) based two-dimensional angle sensor was used in this probe, which can detect the ball tip’s 3D motions of the probe precisely at the same time. The probe was introduced and analyzed. The sensitivity and stiffness models of the probe were achieved, and the optimal structural parameters of the probe were obtained. Several experiments have been conducted to test the stiffness, measurement range, sensitivity and repeatability of the probe. The experimental results demonstrate that the probe has 1 mN/μm uniform stiffness in 3D, the permitted measurement range is more than 12μm and the sensitivity is about 0.5 mV/nm in 3D. The drift is about 20 nm in 1.3 hours when the environment temperature is controlled to (20±0.025)℃, and the repeatability is less than 40 nm (K=2). The probe has the advantages of high precision, low stiffness, small size, low cost and good assembly which can be applied to Micro/Nano CMM.%为解决微电子机械系统(MEMS)器件三维尺寸高精度测量的难题,研制了一种适用于微纳米三坐标测量机的新型高精度三维接触触发式探头。该探头只用了一个基于四象限感测器的二维角度传感器即可同时实现对测球三维运动的高精度感测。介绍了探头的结构和原理,建立了探头的灵敏度模型和刚度模型,用最优化方法得出了探头结构参数的最优解。对探头的刚度、感测范围、灵敏度、稳定性及触发重复性等性能指标进行了测试。实验结果表明:探头的刚度在三轴方向基本相同,约为1 mN/μm;允许触碰范围超过12μm;灵敏度大于0.5 mV/nm;在恒温环境(20±0.025)℃下,1.3 h内的位移漂移量约为20 nm;触发测量重复性小于40 nm(K=2)。该探头具有精度高、测力小、体积小、成本低、装调

  17. Preparation of Hierarchical Porous Structure on Ti Surface and Bioactivity%钛基体表面多级孔洞结构的制备和生物活性研究

    Institute of Scientific and Technical Information of China (English)

    朱洪强; 何宏燕; 袁媛; 刘昌胜

    2015-01-01

    titanate, as well as rutile TiO2 , was the main component of coating. The porous structure exhibited good apatite-inducing ability in SBF. Many bone-like apatite crystals were formed on AHT-titanium surface after 7 d immersion and the mineralization behavior exhibited even better after 14 d. Conclusion AHT-titanium with micro/nano pores exhibits the good inducibility for hydroxyapatite formation, which has a promotion effect on its biological activity.

  18. Structure, dynamics and evolution of disk galaxies in a hierarchical formation scenario

    CERN Document Server

    Firmani, C

    1999-01-01

    Using galaxy evolutionary models in a hierarchical formation scenario, we predict the structure, dynamics and evolution of disk galaxies in a LCDM universe. Our models include star formation and hydrodynamics of the ISM. We find that the Tully-Fisher relation (TFR) in the I and H bands is an imprint of the mass-velocity relation of the cosmological dark halos. The scatter of the TFR originates mainly from the scatter in the dark halo structure and, to a minor extension, from the dispersion of the primordial spin parameter lambda. Our models allow us to explain why low and high surface brightness galaxies have the same TFR. The disk gas fractions predicted agree with the observations. The disks formed within the growing halos have nearly exponential surface brightness and flat rotation curves. Towards high redshifts, the zero-point of the TFR in the H band increases while in the B-band it slightly decreases.

  19. Superior water repellency of water strider legs with hierarchical structures: experiments and analysis.

    Science.gov (United States)

    Feng, Xi-Qiao; Gao, Xuefeng; Wu, Ziniu; Jiang, Lei; Zheng, Quan-Shui

    2007-04-24

    Water striders are a type of insect with the remarkable ability to stand effortlessly and walk quickly on water. This article reports the water repellency mechanism of water strider legs. Scanning electron microscope (SEM) observations reveal the uniquely hierarchical structure on the legs, consisting of numerous oriented needle-shaped microsetae with elaborate nanogrooves. The maximal supporting force of a single leg against water surprisingly reaches up to 152 dynes, about 15 times the total body weight of this insect. We theoretically demonstrate that the cooperation of nanogroove structures on the oriented microsetae, in conjunction with the wax on the leg, renders such water repellency. This finding might be helpful in the design of innovative miniature aquatic devices and nonwetting materials.

  20. Fischer-Tropsch synthesis on hierarchically structured cobalt nanoparticle/carbon nanofiber/carbon felt composites.

    Science.gov (United States)

    Zarubova, Sarka; Rane, Shreyas; Yang, Jia; Yu, Yingda; Zhu, Ye; Chen, De; Holmen, Anders

    2011-07-18

    The hierarchically structured carbon nanofibers (CNFs)/carbon felt composites, in which CNFs were directly grown on the surface of microfibers in carbon felt, forming a CNF layer on a micrometer range that completely covers the microfiber surfaces, were tested as a novel support material for cobalt nanoparticles in the highly exothermic Fischer-Tropsch (F-T) synthesis. A compact, fixed-bed reactor, made of disks of such composite materials, offered the advantages of improved heat and mass transfer, relatively low pressure drop, and safe handling of immobilized CNFs. An efficient 3-D thermal conductive network in the composite provided a relatively uniform temperature profile, whereas the open structure of the CNF layer afforded an almost 100 % effectiveness of Co nanoparticles in the F-T synthesis in the fixed bed. The greatly improved mass and heat transport makes the compact reactor attractive for applications in the conversion of biomass, coal, and natural gas to liquids.

  1. Asymmetric flexural behavior from bamboo's functionally graded hierarchical structure: underlying mechanisms.

    Science.gov (United States)

    Habibi, Meisam K; Samaei, Arash T; Gheshlaghi, Behnam; Lu, Jian; Lu, Yang

    2015-04-01

    As one of the most renewable resources on Earth, bamboo has recently attracted increasing interest for its promising applications in sustainable structural purposes. Its superior mechanical properties arising from the unique functionally-graded (FG) hierarchical structure also make bamboo an excellent candidate for bio-mimicking purposes in advanced material design. However, despite its well-documented, impressive mechanical characteristics, the intriguing asymmetry in flexural behavior of bamboo, alongside its underlying mechanisms, has not yet been fully understood. Here, we used multi-scale mechanical characterizations assisted with advanced environmental scanning electron microscopy (ESEM) to investigate the asymmetric flexural responses of natural bamboo (Phyllostachys edulis) strips under different loading configurations, during "elastic bending" and "fracture failure" stages, with their respective deformation mechanisms at microstructural level. Results showed that the gradient distribution of the vascular bundles along the thickness direction is mainly responsible for the exhibited asymmetry, whereas the hierarchical fiber/parenchyma cellular structure plays a critical role in alternating the dominant factors for determining the distinctly different failure mechanisms. A numerical model has been likewise adopted to validate the effective flexural moduli of bamboo strips as a function of their FG parameters, while additional experiments on uniaxial loading of bamboo specimens were performed to assess the tension-compression asymmetry, for further understanding of the microstructure evolution of bamboo's outer and innermost layers under different bending states. This work could provide insights to help the processing of novel bamboo-based composites and enable the bio-inspired design of advanced structural materials with desired flexural behavior.

  2. The porous carbon derived from water hyacinth with well-designed hierarchical structure for supercapacitors

    Science.gov (United States)

    Zheng, Kaiwen; Li, Yuanyuan; Zhu, Ming; Yu, Xi; Zhang, Mengyan; Shi, Ling; Cheng, Jue

    2017-10-01

    A hierarchical porous water hyacinth-derived carbon (WHC) is fabricated by pre-carbonization and KOH activation for supercapacitors. The physicochemical properties of WHC are researched by scanning electron microscopy (SEM), N2 adsorption-desorption measurements, X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results indicate that WHC exhibits hierarchical porous structure and high specific surface area of 2276 m2/g. And the electrochemical properties of WHC are studied by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) tests. In a three-electrode test system, WHC shows considerable specific capacitance of 344.9 F/g at a current density of 0.5 A/g, good rate performance with 225.8 F/g even at a current density of 30 A/g, and good cycle stability with 95% of the capacitance retention after 10000 cycles of charge-discharge at a current density of 5 A/g. Moreover, WHC cell delivers an energy density of 23.8 Wh/kg at 0.5 A/g and a power density of 15.7 kW/kg at 10 A/g. Thus, using water hyacinth as carbon source to fabricate supercapacitors electrodes is a promising approach for developing inexpensive, sustainable and high-performance carbon materials. Additionally, this study supports the sustainable development and the control of biological invasion.

  3. Highly Stretchable Superhydrophobic Composite Coating Based on Self-Adaptive Deformation of Hierarchical Structures.

    Science.gov (United States)

    Hu, Xin; Tang, Changyu; He, Zhoukun; Shao, Hong; Xu, Keqin; Mei, Jun; Lau, Woon-Ming

    2017-05-01

    With the rapid development of stretchable electronics, functional textiles, and flexible sensors, water-proof protection materials are required to be built on various highly flexible substrates. However, maintaining the antiwetting of superhydrophobic surface under stretching is still a big challenge since the hierarchical structures at hybridized micro-nanoscales are easily damaged following large deformation of the substrates. This study reports a highly stretchable and mechanically stable superhydrophobic surface prepared by a facile spray coating of carbon black/polybutadiene elastomeric composite on a rubber substrate followed by thermal curing. The resulting composite coating can maintain its superhydrophobic property (water contact angle ≈170° and sliding angle superhydrophobic property. Furthermore, the experimental observation and modeling analysis reveal that the stable superhydrophobic properties of the composite coating are attributed to the unique self-adaptive deformation ability of 3D hierarchical roughness of the composite coating, which delays the Cassie-Wenzel transition of surface wetting. In addition, it is first observed that the damaged coating can automatically recover its superhydrophobicity via a simple stretching treatment without incorporating additional hydrophobic materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Construct validity of the WISC-IV with a referred sample: direct versus indirect hierarchical structures.

    Science.gov (United States)

    Canivez, Gary L

    2014-03-01

    The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) is one of the most frequently used intelligence tests in clinical assessments of children with learning difficulties. Construct validity studies of the WISC-IV have generally supported the higher order structure with four correlated first-order factors and one higher-order general intelligence factor, but recent studies have supported an alternate model in which general intelligence is conceptualized as a breadth factor rather than a superordinate factor (M. W. Watkins, 2010, Structure of the Wechsler Intelligence Scale for Children-Fourth Edition among a national sample of referred students, Psychological Assessment, Vol. 22, pp. 782-787; M. W. Watkins, G. L. Canivez, T. James, K. & R. Good, in press, Construct validity of the WISC-IVUK with a large referred Irish sample, International Journal of School and Educational Psychology). WISC-IV core subtest data obtained from evaluations to assess learning difficulties in 345 children (224 boys, 121 girls) were examined. One through four, first order factor models and indirect versus direct hierarchical models were compared using confirmatory factor analyses. The correlated four-factor Wechsler model provided good fit to these data, but the direct hierarchical model showed statistically significant improvement over the indirect hierarchical model and correlated four-factor model. The direct hierarchical model was judged the best explanation of the WISC-IV factor structure, with the general factor accounting for 71.6% of the common variance while the first order factors accounted for 2.4-10.3% of the common variance. Thus, the results with the present sample of referred children were similar to those from other investigations (G. E. Gignac, 2005, Revisiting the factor structure of the WAIS-R: Insights through nested factor modeling, Assessment, Vol. 12, pp. 320-329; G. E. Gignac, 2006, The WAIS-III as a nested factors model: A useful alternative to

  5. Light-Emitting Diodes with Hierarchical and Multifunctional Surface Structures for High Light Extraction and an Antifouling Effect.

    Science.gov (United States)

    Leem, Young-Chul; Park, Jung Su; Kim, Joon Heon; Myoung, NoSoung; Yim, Sang-Youp; Jeong, Sehee; Lim, Wantae; Kim, Sung-Tae; Park, Seong-Ju

    2016-01-13

    Bioinspired hierarchical structures on the surface of vertical light-emitting diodes (VLEDs) are demonstrated by combining a self-assembled dip-coating process and nanopatterning transfer method using thermal release tape. This versatile surface structure can efficiently reduce the total internal reflection and add functions, such as superhydrophobicity and high oleophobicity, to achieve an antifouling effect for VLEDs.

  6. Determination of genetic structure of germplasm collections: are traditional hierarchical clustering methods appropriate for molecular marker data?

    Science.gov (United States)

    Odong, T L; van Heerwaarden, J; Jansen, J; van Hintum, T J L; van Eeuwijk, F A

    2011-07-01

    Despite the availability of newer approaches, traditional hierarchical clustering remains very popular in genetic diversity studies in plants. However, little is known about its suitability for molecular marker data. We studied the performance of traditional hierarchical clustering techniques using real and simulated molecular marker data. Our study also compared the performance of traditional hierarchical clustering with model-based clustering (STRUCTURE). We showed that the cophenetic correlation coefficient is directly related to subgroup differentiation and can thus be used as an indicator of the presence of genetically distinct subgroups in germplasm collections. Whereas UPGMA performed well in preserving distances between accessions, Ward excelled in recovering groups. Our results also showed a close similarity between clusters obtained by Ward and by STRUCTURE. Traditional cluster analysis can provide an easy and effective way of determining structure in germplasm collections using molecular marker data, and, the output can be used for sampling core collections or for association studies.

  7. One-step synthesis of hierarchically porous carbons for high-performance electric double layer supercapacitors

    Science.gov (United States)

    Zhang, Haitao; Zhang, Lei; Chen, Jun; Su, Hai; Liu, Fangyan; Yang, Weiqing

    2016-05-01

    With plenty of unique porous structure at micro-/nano scale, hierarchically porous carbons (HPCs) are promising for usage in advanced electric double layer supercapacitors (EDLCs) as the electrode materials. However, wide-range adoption of HPC for practical application is largely shadowed by its extremely complex synthesis process with considerably low production efficiency. Herein we reported a simple template-free, one-step sintering method, to massively produce the HPCs for high-performance EDLCs. Resorting to the 3D structure modification of the wide pore size distribution, high surface area of HPCs (up to 3000 m2 g-1) was achieved. By using 1 M Na2SO4 as electrolyte, the as-fabricated HPCs based EDLCs can be operated reversibly over a wide voltage window of 1.6 V with superior specific capacitance of 240 F g-1 under a current density of 0.5 A g-1. In the meanwhile, the EDLCs exhibit excellent rate capability (high power density of 16 kW kg-1 at 10.2 Wh kg-1) and long-term cycling stability with 9% loss of its initial capacitance after 2000 cycles. This output performance distinguished itself among most of the carbon-based EDLCs with neutral aqueous electrolyte. Thus, the template-free one-step sintering method produced HPCs for EDLCs represents a new approach for high-performance energy storage.

  8. Self-similar Hierarchical Wrinkles as a Potential Multifunctional Smart Window with Simultaneously Tunable Transparency, Structural Color, and Droplet Transport.

    Science.gov (United States)

    Lin, Gaojian; Chandrasekaran, Prashant; Lv, Cunjing; Zhang, Qiuting; Tang, Yichao; Han, Lin; Yin, Jie

    2017-08-09

    Smart window has immense potential for energy savings in architectural and vehicular applications, while most studies focus on the tunability of a single property of optical transmittance. Here we explore harnessing dynamically tunable hierarchical wrinkles for design of a potential multifunctional smart window with combined structural color and water droplet transport control. The self-similar hierarchical wrinkles with both nanoscale and microscale features are generated on a prestrained poly(dimethylsiloxane) elastomer through sequential strain release and multistep oxygen plasma treatment. We show that the hierarchically wrinkled elastomer displays both opaqueness and iridescent structural color. We find that restretching/releasing the elastomer leads to the reversible and repeatable switch from opaqueness to transparency, arising from the flattening of large wrinkles (micrometer scale), while a nonvanishing structural color occurs due to the nondisappearing small wrinkles (nanoscale). The unique features of combined reversible large wrinkles and irreversible small wrinkles during hierarchical wrinkling are well reproduced by corresponding finite element simulation. The criteria for generating self-similar hierarchical wrinkles is revealed through a simplified theoretical model and validated by experiments. In addition to its tunable optical property, we further show its ability in control of water droplet transport on demand through mechanical stretching and release. We find that an initially pinned water droplet on the tilted hierarchically wrinkled surface starts to slide when the surface is stretched, and becomes pinned again upon strain release. Such a process is reversible and repeatable. The hierarchically wrinkled surface could find broad potential applications not only in multifunctional smart windows with additional features of aesthetics and water collection, but in microfluidics, design of slippery surfaces, and directional water transportation.

  9. Multiscale mechanics of hierarchical structure/property relationships in calcified tissues and tissue/material interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Katz, J. Lawrence [School of Computing and Engineering, University of Missouri-Kansas City, Kansas City, MO (United States) and School of Dentistry, University of Missouri-Kansas City, Kansas City, MO (United States)]. E-mail: katzjl@umkc.edu; Misra, Anil [School of Computing and Engineering, University of Missouri-Kansas City, Kansas City, MO (United States); Spencer, Paulette [School of Dentistry, University of Missouri-Kansas City, Kansas City, MO (United States); Wang, Yong [School of Dentistry, University of Missouri-Kansas City, Kansas City, MO (United States); Bumrerraj, Sauwanan [School of Medicine, Khon Kaen University, Khon Kaen (Thailand); Nomura, Tsutomu [School of Dentistry, Niigata University, Niigata (Japan); Eppell, Steven J. [Case School of Engineering, Case Western Reserve University, Cleveland, OH (United States); Tabib-Azar, Massood [Case School of Engineering, Case Western Reserve University, Cleveland, OH (United States)

    2007-04-15

    This paper presents a review plus new data that describes the role hierarchical nanostructural properties play in developing an understanding of the effect of scale on the material properties (chemical, elastic and electrical) of calcified tissues as well as the interfaces that form between such tissues and biomaterials. Both nanostructural and microstructural properties will be considered starting with the size and shape of the apatitic mineralites in both young and mature bovine bone. Microstructural properties for human dentin and cortical and trabecular bone will be considered. These separate sets of data will be combined mathematically to advance the effects of scale on the modeling of these tissues and the tissue/biomaterial interfaces as hierarchical material/structural composites. Interfacial structure and properties to be considered in greatest detail will be that of the dentin/adhesive (d/a) interface, which presents a clear example of examining all three material properties, (chemical, elastic and electrical). In this case, finite element modeling (FEA) was based on the actual measured values of the structure and elastic properties of the materials comprising the d/a interface; this combination provides insight into factors and mechanisms that contribute to premature failure of dental composite fillings. At present, there are more elastic property data obtained by microstructural measurements, especially high frequency ultrasonic wave propagation (UWP) and scanning acoustic microscopy (SAM) techniques. However, atomic force microscopy (AFM) and nanoindentation (NI) of cortical and trabecular bone and the dentin-enamel junction (DEJ) among others have become available allowing correlation of the nanostructural level measurements with those made on the microstructural level.

  10. Mechanics of robust and releasable adhesion in biology: Bottom up designed hierarchical structures of gecko

    Science.gov (United States)

    Yao, Haimin; Gao, Huajian

    2006-06-01

    Gecko and many insects have evolved specialized adhesive tissues with bottom-up designed (from nanoscale and up) hierarchical structures that allow them to maneuver on vertical walls and ceilings. The adhesion mechanisms of gecko must be robust enough to function on unknown rough surfaces and also easily releasable upon animal movement. How does nature design such macroscopic sized robust and releasable adhesion devices? How can an adhesion system designed for robust attachment simultaneously allow easy detachment? These questions have motivated the present investigation on mechanics of robust and releasable adhesion in biology. On the question of robust adhesion, we introduce a fractal gecko hairs model, which assumes self-similar fibrillar structures at multiple hierarchical levels mimicking gecko's spatula ultrastructure, to show that structural hierarchy plays a key role in robust adhesion: it allows the work of adhesion to be exponentially enhanced with each added level of hierarchy. We demonstrate that, barring fiber fracture, the fractal gecko hairs can be designed from nanoscale and up to achieve flaw tolerant adhesion at any length scales. However, consideration of crack-like flaws in the hairs themselves results in an upper size limit for flaw tolerant design. On the question of releasable adhesion, we hypothesize that the asymmetrically aligned seta hairs of gecko form a strongly anisotropic material with adhesion strength strongly varying with the direction of pulling. We use analytical solutions to show that a strongly anisotropic elastic solid indeed exhibits a strongly anisotropic adhesion strength when sticking on a rough surface. Furthermore, we perform finite element calculations to show that the adhesion strength of a strongly anisotropic attachment pad exhibits essentially two levels of adhesion strength depending on the direction of pulling, resulting in an orientation-controlled switch between attachment and detachment. These findings not only

  11. Hierarchical composite structures prepared by electrophoretic deposition of carbon nanotubes onto glass fibers.

    Science.gov (United States)

    An, Qi; Rider, Andrew N; Thostenson, Erik T

    2013-03-01

    Carbon nanotube/glass fiber hierarchical composite structures have been produced using an electrophoretic deposition (EPD) approach for integrating the carbon nanotubes (CNTs) into unidirectional E-glass fabric, followed by infusion of an epoxy polymer matrix. The resulting composites show a hierarchical structure, where the structural glass fibers, which have diameters in micrometer range, are coated with CNTs having diameters around 10-20 nm. The stable aqueous dispersions of CNTs were produced using a novel ozonolysis and ultrasonication technique that results in dispersion and functionalization in a single step. Ozone-oxidized CNTs were then chemically reacted with a polyethyleneimine (PEI) dendrimer to enable cathodic EPD and promote adhesion between the CNTs and the glass-fiber substrate. Deposition onto the fabric was accomplished by placing the fabric in front of the cathode and applying a direct current (DC) field. Microscopic characterization shows the integration of CNTs throughout the thickness of the glass fabric, where individual fibers are coated with CNTs and a thin film of CNTs also forms on the fabric surfaces. Within the composite, networks of CNTs span between adjacent fibers, and the resulting composites exhibit good electrical conductivity and considerable increases in the interlaminar shear strength, relative to fiber composites without integrated CNTs. Mechanical, chemical and morphological characterization of the coated fiber surfaces reveal interface/interphase modification resulting from the coating is responsible for the improved mechanical and electrical properties. The CNT-coated glass-fiber laminates also exhibited clear changes in electrical resistance as a function of applied shear strain and enables self-sensing of the transition between elastic and plastic load regions.

  12. Active Antifogging Property of Monolayer SiO2 Film with Bioinspired Multiscale Hierarchical Pagoda Structures.

    Science.gov (United States)

    Han, Zhiwu; Mu, Zhengzhi; Li, Bo; Wang, Ze; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

    2016-09-27

    Antifogging surfaces with hydrophilic or even superhydrophilic wetting behavior have received significant attention due to their ability to reduce light scattering by film-like condensation. However, a major challenge remains in achieving high-speed antifogging performance and revealing the hydrophilic-based antifogging mechanism of glass or other transparent materials under aggressive fogging conditions. Herein, with inspiration from the fog-free property of the typical Morpho menelaus terrestris butterfly (Butler, 1866) wing scales, a monolayer SiO2 film with multiscale hierarchical pagoda structures (MHPSs) based on glass substrate was designed and fabricated using an optimized biotemplate-assisted wet chemical method without any post-treatments. The biomimetic monolayer film (BMF) composed of nanoscale SiO2 3D networks displayed excellent antifogging properties, which is superior to that of the glass substrate itself. The MHPS-based BMF even kept high transmittance (∼95%) under aggressive fog conditions, and it almost instantaneously recovered to a fog-free state (properties mainly benefit from the synergistic effect of both hydrophilic chemical compositions (nanoscale SiO2) and physical structures (biomimetic MHPSs) of the BMF. High-speed active antifogging performance of the glass materials enabled the retention of a high transmittance property even in humid conditions, heralding reliable optical performance in outdoor practical applications, especially in aggressive foggy environments. More importantly, the investigations in this work offer a promising way to handily design and fabricate quasi-textured surfaces with multiscale hierarchical structures that possess high-performance physicochemical properties.

  13. The relationship between carbon dioxide emission and economic growth: Hierarchical structure methods

    Science.gov (United States)

    Deviren, Seyma Akkaya; Deviren, Bayram

    2016-06-01

    Carbon dioxide (CO2) emission has an essential role in the current debate on sustainable development and environmental protection. CO2 emission is also directly linked with use of energy which plays a focal role both for production and consumption in the world economy. Therefore the relationship between the CO2 emission and economic growth has a significant implication for the environmental and economical policies. In this study, within the scope of sociophysics, the topology, taxonomy and relationships among the 33 countries, which have almost the high CO2 emission and economic growth values, are investigated by using the hierarchical structure methods, such as the minimal spanning tree (MST) and hierarchical tree (HT), over the period of 1970-2010. The average linkage cluster analysis (ALCA) is also used to examine the cluster structure more clearly in HTs. According to their proximity, economic ties and economic growth, different clusters of countries are identified from the structural topologies of these trees. We have found that the high income & OECD countries are closely connected to each other and are isolated from the upper middle and lower middle income countries from the MSTs, which are obtained both for the CO2 emission and economic growth. Moreover, the high income & OECD clusters are homogeneous with respect to the economic activities and economic ties of the countries. It is also mentioned that the Group of Seven (G7) countries (CAN, ENG, FRA, GER, ITA, JPN, USA) are connected to each other and these countries are located at the center of the MST for the results of CO2 emission. The same analysis may also successfully apply to the other environmental sources and different countries.

  14. Hierarchical columnar silicon anode structures for high energy density lithium sulfur batteries

    Science.gov (United States)

    Piwko, Markus; Kuntze, Thomas; Winkler, Sebastian; Straach, Steffen; Härtel, Paul; Althues, Holger; Kaskel, Stefan

    2017-05-01

    Silicon is a promising anode material for next generation lithium secondary batteries. To significantly increase the energy density of state of the art batteries with silicon, new concepts have to be developed and electrode structuring will become a key technology. Structuring is essential to reduce the macroscopic and microscopic electrode deformation, caused by the volume change during cycling. We report pulsed laser structuring for the generation of hierarchical columnar silicon films with outstanding high areal capacities up to 7.5 mAh cm-2 and good capacity retention. Unstructured columnar electrodes form a micron-sized block structure during the first cycle to compensate the volume expansion leading to macroscopic electrode deformation. At increased silicon loading, without additional structuring, pronounced distortion and the formation of cracks through the current collector causes cell failure. Pulsed laser ablation instead is demonstrated to avoid macroscopic electrode deformation by initial formation of the block structure. A full cell with lithiated silicon versus a carbon-sulfur cathode is assembled with only 15% overbalanced anode and low electrolyte amount (8 μl mgsulfur-1). While the capacity retention over 50 cycles is identical to a cell with high excess lithium anode, the volumetric energy density could be increased by 30%.

  15. Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

    Institute of Scientific and Technical Information of China (English)

    Mengjie Xu; Rongjun Xu; Ying Zhao; Libao Chen; Boyun Huang; Weifeng Wei n

    2016-01-01

    A variety of NiCo2O4 nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4 with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional (3D) metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.

  16. Hierarchically porous Ni monolith@branch-structured NiCo2O4 for high energy density supercapacitors

    Directory of Open Access Journals (Sweden)

    Mengjie Xu

    2016-06-01

    Full Text Available A variety of NiCo2O4 nanostrucutures ranging from nanowire to nanoplate and branched structures were successfully prepared via a simple hydrothermal process. The experimental results show that NiCo2O4 with branched structures possesses the best overall electrochemical performance. The improvement of energy density was explored in terms of hierarchically three-dimensional (3D metal substrates and a high specific area capacitance, and area energy density is obtained with hierarchically porous Ni monolith synthesized through a controlled combustion procedure.

  17. Micro/nano-mechanical test system employing tensile test holder with push-to-pull transformer

    Science.gov (United States)

    Oh, Yunje; Cyrankowski, Edward; Shan, Zhiwei; Asif, Syed Amanula Syed

    2013-05-07

    A micromachined or microelectromechanical system (MEMS) based push-to-pull mechanical transformer for tensile testing of micro-to-nanometer scale material samples including a first structure and a second structure. The second structure is coupled to the first structure by at least one flexible element that enables the second structure to be moveable relative to the first structure, wherein the second structure is disposed relative to the first structure so as to form a pulling gap between the first and second structures such that when an external pushing force is applied to and pushes the second structure in a tensile extension direction a width of the pulling gap increases so as to apply a tensile force to a test sample mounted across the pulling gap between a first sample mounting area on the first structure and a second sample mounting area on the second structure.

  18. Micro/nano-mechanical test system employing tensile test holder with push-to-pull transformer

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Yunje; Cyrankowski, Edward; Shan, Zhiwei; Syed Asif, Syed Amanula

    2014-07-29

    A micromachined or microelectromechanical system (MEMS) based push-to-pull mechanical transformer for tensile testing of micro-to-nanometer scale material samples including a first structure and a second structure. The second structure is coupled to the first structure by at least one flexible element that enables the second structure to be moveable relative to the first structure, wherein the second structure is disposed relative to the first structure so as to form a pulling gap between the first and second structures such that when an external pushing force is applied to and pushes the second structure in a tensile extension direction a width of the pulling gap increases so as to apply a tensile force to a test sample mounted across the pulling gap between a first sample mounting area on the first structure and a second sample mounting area on the second structure.

  19. Influence of structured sidewalls on the wetting states and superhydrophobic stability of surfaces with dual-scale roughness

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huaping, E-mail: wuhuaping@gmail.com [Key Laboratory of E& M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014 (China); State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024 (China); Zhu, Kai; Wu, Bingbing [Key Laboratory of E& M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014 (China); Lou, Jia [Piezoelectric Device Laboratory, Department of Mechanics and Engineering Science, Ningbo University, Ningbo, Zhejiang 315211 (China); Zhang, Zheng [Key Laboratory of E& M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014 (China); Chai, Guozhong, E-mail: chaigz@zjut.edu.cn [Key Laboratory of E& M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014 (China)

    2016-09-30

    Highlights: • Apparent contact angle equation of all wetting states on dual-scale rough surfaces is derived. • Structured sidewalls can improve superhydrophobicity than smooth sidewalls. • Structured sidewalls can enlarge ACA than smooth sidewalls. • Structured sidewalls present an advantage over smooth sidewalls in terms of enhancing superhydrophobic stability. - Abstract: The superhydrophobicity of biological surfaces with dual-scale roughness has recently received considerable attention because of the unique wettability of such surfaces. Based on this, artificial micro/nano hierarchical structures with structured sidewalls and smooth sidewalls were designed and the influences of sidewall configurations (i.e., structured and smooth) on the wetting state of micro/nano hierarchical structures were systematically investigated based on thermodynamics and the principle of minimum free energy. Wetting transition and superhydrophobic stability were then analyzed for a droplet on dual-scale rough surfaces with structured and smooth sidewalls. Theoretical analysis results show that dual-scale rough surfaces with structured sidewalls have a larger “stable superhydrophobic region” than those with smooth sidewalls. The dual-scale rough surfaces with smooth sidewalls can enlarge the apparent contact angle (ACA) without improvement in the superhydrophobic stability. By contrast, dual-scale rough surfaces with structured sidewalls present an advantage over those with smooth sidewalls in terms of enlarging ACA and enhancing superhydrophobic stability. The proposed thermodynamic model is valid when compared with previous experimental data and numerical analysis results, which is helpful for designing and understanding the wetting states and superhydrophobic stability of surfaces with dual-scale roughness.

  20. Multicast Address Management and Connection Control Based on Hierarchical Autonomous Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; ZHANG Fuyan

    1999-01-01

    Multicast capability, including multicast address and multicast routing mechanisms, at the network layeris necessary in order to reduce the bandwidth requirements of multiparty, multicast applications. Based on hierarchical autonomous structure in accordance with the self-organization topologies of Internet, the paper puts forward a multicast address management scheme that is shown to be robust and scalable. Connection control hierarchy (CCH) based on master/slave relationship and a simple efficient building algorithm of multi-point connection is also built. The paper also describes the normal operations of multicast address management andmulti-point connection controller. Through simulation experiment, HAM, CM and DDM of Multicast Address Allocation are compared. HAM integrates the merits of CM and DDM, which is efficient as a whole, robust andscalable. CCH raises the efficiency of connection control, and is highly robust, flexible and scalable.

  1. 3D Nearest Neighbour Search Using a Clustered Hierarchical Tree Structure

    DEFF Research Database (Denmark)

    Suhaibah, A.; Uznir, U.; Antón Castro, Francesc/François

    2016-01-01

    , with the immense number of urban datasets, the retrieval and analysis of nearest neighbour information and their efficiency will become more complex and crucial. In this paper, we present a technique to retrieve nearest neighbour information in 3D space using a clustered hierarchical tree structure. Based on our...... findings, the proposed approach substantially showed an improvement of response time analysis compared to existing approaches of spatial access methods in databases. The query performance was tested using a dataset consisting of 500,000 point locations building and franchising unit. The results...... of the franchise unit will be located or is the franchise unit located is at the best level for visibility purposes. One of the common used analyses used for retrieving the surrounding information is Nearest Neighbour (NN) analysis. It uses a point location and identifies the surrounding neighbours. However...

  2. Hierarchical structural control of visual properties in self-assembled photonic-plasmonic pigments

    CERN Document Server

    Koay, Natalie; Kay, Theresa M; Nerger, Bryan A; Miles-Rossouw, Malaika; Shirman, Tanya; Vu, Thy L; England, Grant; Phillips, Katherine R; Utech, Stefanie; Vogel, Nicolas; Kolle, Mathias; Aizenberg, Joanna

    2014-01-01

    We present a simple one-pot co-assembly method for the synthesis of hierarchically structured pigment particles consisting of silica inverse-opal bricks that are doped with plasmonic absorbers. We study the interplay between the plasmonic and photonic resonances and their effect on the visual appearance of macroscopic collections of photonic bricks that are distributed in randomized orientations. Manipulating the pore geometry tunes the wavelength- and angle-dependence of the scattering profile, which can be engineered to produce angle-dependent Bragg resonances that can either enhance or contrast with the color produced by the plasmonic absorber. By controlling the overall dimensions of the photonic bricks and their aspect ratios, their preferential alignment can either be encouraged or suppressed. This causes the Bragg resonance to appear either as uniform color travel in the former case or as sparse iridescent sparkle in the later case. By manipulating the surface chemistry of these photonic bricks, which ...

  3. Hierarchical structured TiO2 photoanodes for dye-sensitized solar cells.

    Science.gov (United States)

    Shih, Yen-Chen; Chu, Ann-Kuo; Huang, Wen-Yao

    2012-04-01

    A novel approach has been developed to fabricate hills-like hierarchical structured TiO2 photoanodes for dye-sensitized solar cells (DSSCs). The appropriately aggregated TiO2 clusters in the photoanode layer could cause stronger light scattering and higher dye loading that increases the efficiency of photovoltaic device. For detailed light-harvesting study, different molecular weights of polyvinyl alcohol (PVA) were used as binders for TiO2 nanoparticles (P-25 Degussa) aggregation. A series of TiO2 films with dissimilar morphology, the reflection of TiO2 films, absorbance of attached dye, amount of dye loading, and performance of fabricated DSSC devices, were measured and investigated. An optimized device had energy conversion efficiency of 4.47% having a higher dye loading and good light harvesting, achieving a 23% increase of short-circuit current J(sc) in DSSCs.

  4. Identifying rock blocks based on hierarchical rock-mass structure model

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Rock-masses are divided into many closed blocks by deterministic and stochastic discontinuities and engineering interfaces in complex rock-mass engineering. Determining the sizes, shapes, and adjacent relations of blocks is important for stability analysis of fractured rock masses. Here we propose an algorithm for identifying spatial blocks based on a hierarchical 3D Rock-mass Structure Model (RSM). First, a model is built composed of deterministic discontinuities, engineering interfaces, and the earth’s surface, and the deterministic blocks surrounded by these interfaces are traced. Then, in each deter-ministic block, a network model of stochastic discontinuities is built and the stochastic blocks are traced. Building a unitary wire frame that connects all interfaces seamlessly is the key for our algorithm to identify the above two kinds of blocks. Using this algorithm, geometric models can be built for block theory, discrete element method, and discontinuous deformation analysis.

  5. Synthesis and properties of flexible nanocable with carbon nanotube @ polymer hierarchical structure

    Science.gov (United States)

    Ren, Junwen; Wang, Xiaoguang; Narayan Ramasubramanian, Lakshmi; Dong, Chengye; Cheng, Yonghong; Yu, Demei; Shan, Zhiwei

    2017-03-01

    A multi-functional polymer–carbon nanotube (CNT) nanocable with a hierarchical structure is fabricated by grafting poly (glycidyl methacrylate) (PGMA) from the CNT surface via activators regenerated by electron transfer atom transfer radical polymerization. Multiple CNTs are arranged in parallel in the fabricated nanocable and exhibit strong binding force with sheathing PGMA. In situ mechanical and electrical tests conducted on an individual nanocable reveal its high flexibility and excellent surface insulation, with an electrical resistance of approximately 1 GΩ. On increasing the voltage to the nanocable’s electrical breakdown point, nanoscale electrical trees are observed. Such degradation behavior is discussed in the wider context of breakdown mechanisms in polymer based CNTs.

  6. A hierarchical model for structure learning based on the physiological characteristics of neurons

    Institute of Scientific and Technical Information of China (English)

    WEI Hui

    2007-01-01

    Almost all applications of Artificial Neural Networks (ANNs) depend mainly on their memory ability.The characteristics of typical ANN models are fixed connections,with evolved weights,globalized representations,and globalized optimizations,all based on a mathematical approach.This makes those models to be deficient in robustness,efficiency of learning,capacity,anti-jamming between training sets,and correlativity of samples,etc.In this paper,we attempt to address these problems by adopting the characteristics of biological neurons in morphology and signal processing.A hierarchical neural network was designed and realized to implement structure learning and representations based on connected structures.The basic characteristics of this model are localized and random connections,field limitations of neuron fan-in and fan-out,dynamic behavior of neurons,and samples represented through different sub-circuits of neurons specialized into different response patterns.At the end of this paper,some important aspects of error correction,capacity,learning efficiency,and soundness of structural representation are analyzed theoretically.This paper has demonstrated the feasibility and advantages of structure learning and representation.This model can serve as a fundamental element of cognitive systems such as perception and associative memory.Key-words structure learning,representation,associative memory,computational neuroscience

  7. Structural system identification using degree of freedom-based reduction and hierarchical clustering algorithm

    Science.gov (United States)

    Chang, Seongmin; Baek, Sungmin; Kim, Ki-Ook; Cho, Maenghyo

    2015-06-01

    A system identification method has been proposed to validate finite element models of complex structures using measured modal data. Finite element method is used for the system identification as well as the structural analysis. In perturbation methods, the perturbed system is expressed as a combination of the baseline structure and the related perturbations. The changes in dynamic responses are applied to determine the structural modifications so that the equilibrium may be satisfied in the perturbed system. In practical applications, the dynamic measurements are carried out on a limited number of accessible nodes and associated degrees of freedom. The equilibrium equation is, in principle, expressed in terms of the measured (master, primary) and unmeasured (slave, secondary) degrees of freedom. Only the specified degrees of freedom are included in the equation formulation for identification and the unspecified degrees of freedom are eliminated through the iterative improved reduction scheme. A large number of system parameters are included as the unknown variables in the system identification of large-scaled structures. The identification problem with large number of system parameters requires a large amount of computation time and resources. In the present study, a hierarchical clustering algorithm is applied to reduce the number of system parameters effectively. Numerical examples demonstrate that the proposed method greatly improves the accuracy and efficiency in the inverse problem of identification.

  8. Estimating the Term Structure With a Semiparametric Bayesian Hierarchical Model: An Application to Corporate Bonds1

    Science.gov (United States)

    Cruz-Marcelo, Alejandro; Ensor, Katherine B.; Rosner, Gary L.

    2011-01-01

    The term structure of interest rates is used to price defaultable bonds and credit derivatives, as well as to infer the quality of bonds for risk management purposes. We introduce a model that jointly estimates term structures by means of a Bayesian hierarchical model with a prior probability model based on Dirichlet process mixtures. The modeling methodology borrows strength across term structures for purposes of estimation. The main advantage of our framework is its ability to produce reliable estimators at the company level even when there are only a few bonds per company. After describing the proposed model, we discuss an empirical application in which the term structure of 197 individual companies is estimated. The sample of 197 consists of 143 companies with only one or two bonds. In-sample and out-of-sample tests are used to quantify the improvement in accuracy that results from approximating the term structure of corporate bonds with estimators by company rather than by credit rating, the latter being a popular choice in the financial literature. A complete description of a Markov chain Monte Carlo (MCMC) scheme for the proposed model is available as Supplementary Material. PMID:21765566

  9. Structure function relationship in complex brain networks expressed by hierarchical synchronization

    Science.gov (United States)

    Zhou, Changsong; Zemanová, Lucia; Zamora-López, Gorka; Hilgetag, Claus C.; Kurths, Jürgen

    2007-06-01

    The brain is one of the most complex systems in nature, with a structured complex connectivity. Recently, large-scale corticocortical connectivities, both structural and functional, have received a great deal of research attention, especially using the approach of complex network analysis. Understanding the relationship between structural and functional connectivity is of crucial importance in neuroscience. Here we try to illuminate this relationship by studying synchronization dynamics in a realistic anatomical network of cat cortical connectivity. We model the nodes (cortical areas) by a neural mass model (population model) or by a subnetwork of interacting excitable neurons (multilevel model). We show that if the dynamics is characterized by well-defined oscillations (neural mass model and subnetworks with strong couplings), the synchronization patterns are mainly determined by the node intensity (total input strengths of a node) and the detailed network topology is rather irrelevant. On the other hand, the multilevel model with weak couplings displays more irregular, biologically plausible dynamics, and the synchronization patterns reveal a hierarchical cluster organization in the network structure. The relationship between structural and functional connectivity at different levels of synchronization is explored. Thus, the study of synchronization in a multilevel complex network model of cortex can provide insights into the relationship between network topology and functional organization of complex brain networks.

  10. Time-domain analysis of neural tracking of hierarchical linguistic structures.

    Science.gov (United States)

    Zhang, Wen; Ding, Nai

    2017-02-01

    When listening to continuous speech, cortical activity measured by MEG concurrently follows the rhythms of multiple linguistic structures, e.g., syllables, phrases, and sentences. This phenomenon was previously characterized in the frequency domain. Here, we investigate the waveform of neural activity tracking linguistic structures in the time domain and quantify the coherence of neural response phases over subjects listening to the same stimulus. These analyses are achieved by decomposing the multi-channel MEG recordings into components that maximize the correlation between neural response waveforms across listeners. Each MEG component can be viewed as the recording from a virtual sensor that is spatially tuned to a cortical network showing coherent neural activity over subjects. This analysis reveals information not available from previous frequency-domain analysis of MEG global field power: First, concurrent neural tracking of hierarchical linguistic structures emerges at the beginning of the stimulus, rather than slowly building up after repetitions of the same sentential structure. Second, neural tracking of the sentential structure is reflected by slow neural fluctuations, rather than, e.g., a series of short-lasting transient responses at sentential boundaries. Lastly and most importantly, it shows that the MEG responses tracking the syllabic rhythm are spatially separable from the MEG responses tracking the sentential and phrasal rhythms.

  11. Hierarchical linear modeling (HLM) of longitudinal brain structural and cognitive changes in alcohol-dependent individuals during sobriety

    DEFF Research Database (Denmark)

    Yeh, P.H.; Gazdzinski, S.; Durazzo, T.C.;

    2007-01-01

    and unique hierarchical linear models allow assessments of the complex relationships among outcome measures of longitudinal data sets. These HLM applications suggest that chronic cigarette smoking modulates the temporal dynamics of brain structural and cognitive changes in alcoholics during prolonged......Background: Hierarchical linear modeling (HLM) can reveal complex relationships between longitudinal outcome measures and their covariates under proper consideration of potentially unequal error variances. We demonstrate the application of FILM to the study of magnetic resonance imaging (MRI...... time points. Using HLM, we modeled volumetric and cognitive outcome measures as a function of cigarette and alcohol use variables. Results: Different hierarchical linear models with unique model structures are presented and discussed. The results show that smaller brain volumes at baseline predict...

  12. The bounds on tracking performance utilising a laser-based linear and angular sensing and measurement methodology for micro/nano manipulation

    OpenAIRE

    Clark, Leon; Shirinzadeh, Bijan; Tian, Yanling; Zhong, Yongmin

    2014-01-01

    This paper presents an analysis of the tracking performance of a planar three degrees of freedom (DOF) flexure-based mechanism for micro/nano manipulation, utilising a tracking methodology for the measurement of coupled linear and angular motions. The methodology permits trajectories over a workspace with large angular range through the reduction of geometric errors. However, when combining this methodology with feedback control systems, the accuracy of performed manipulations can only be sta...

  13. Modelling of seismic-electromagnetic Processes in hierarchic Structures, caused by seism-tectonic Activity

    Science.gov (United States)

    Hachay, Olga; Khachay, Andrey

    2013-04-01

    Rock massive can be described by four functions: structure, physical features, content and state. The last feature plays the main role by forecasting the dynamical events which can occur in it. The energy and intensity of the dynamical events depend from the volume of the massive and the space-time changes of the influence on it. The second feature of the state evolution is: the local volume massive does not immediately respond on the changing of the surrounded it stress state. Therefore it stores the response energy and then extracts it through a high energy dynamical effect. It is very significant to define the time of reaction lagging, in spite of the influence on the massive can be assumed as elastic. The unique model which can explain that effect is a model of the massive with a hierarchic structure. We developed a mathematical algorithm using integral and integral-differential equations for 2-D model for two problems in a frequency domain: diffraction a sound wave and linear polarized transverse wave through a arbitrary hierarchy rank inclusion plunged in an N-layered medium. That algorithm differs from the fractal model approach by a freer selecting of heterogeneities position of each rank. And the second the problem is solved in the dynamical approach. The higher the amount of the hierarchic ranks the more is the degree of nonlinearity of the massive response and the longer can be the time of massive reaction lag of the influence. The paper was supported by the grant RFBR 10-05-00013 Key Words: geosynergetics, theory and experimental results.

  14. Ordered assembly of NiCo₂O₄ multiple hierarchical structures for high-performance pseudocapacitors.

    Science.gov (United States)

    Zhou, Qingwen; Xing, Jiachao; Gao, Yanfang; Lv, Xiaojun; He, Yongmei; Guo, Zihan; Li, Yueming

    2014-07-23

    The design and development of nanomaterials has become central to the advancement of pseudocapacitive performance. Many one-dimensional nanostructures (1D NSs), two-dimensional nanostructures (2D NSs), and three-dimensional hierarchical structures (3D HSs) composed of these building blocks have been synthesized as pseudocapacitive materials via different methods. However, due to the unclear assembly mechanism of these NSs, reports of HSs simultaneously assembled from two or more types of NSs are rare. In this article, NiCo2O4 multiple hierarchical structures (MHSs) composed of 1D nanowires and 2D nanosheets are simply grown on Ni foam using an ordered two-step hydrothermal synthesis followed by annealing processing. The low-dimensional nanowire is found to hold priority in the growth order, rather than the high-dimensional nanosheet, thus effectively promoting the integration of these different NSs in the assembly of the NiCo2O4 MHSs. With vast electroactive surface area and favorable mesoporous architecture, the NiCo2O4 MHSs exhibit a high specific capacitance of up to 2623.3 F g(-1), scaled to the active mass of the NiCo2O4 sample at a current density of 1 A g(-1). A nearly constant rate performance of 68% is achieved at a current density ranging from 1 to 40 A g(-1), and the sample retains approximately 94% of its maximum capacitance even after 3000 continuous charge-discharge cycles at a consistently high current density of 10 A g(-1).

  15. Bio-inspired hierarchical self-assembly of nanotubes into multi-dimensional and multi-scale structures

    Science.gov (United States)

    Liu, Yong; Gao, Yuan; Lu, Qinghua; Zhou, Yongfeng; Yan, Deyue

    2011-12-01

    As inspired from nature's strategy to prepare collagen, herein we report a hierarchical solution self-assembly method to prepare multi-dimensional and multi-scale supra-structures from the building blocks of pristine titanate nanotubes (TNTs) around 10 nm. With the help of amylose, the nanotubes was continuously self-assembled into helically wrapped TNTs, highly aligned fibres, large bundles, 2D crystal facets and 3D core-shell hybrid crystals. The amyloses work as the glue molecules to drive and direct the hierarchical self-assembly process extending from microscopic to macroscopic scale. The whole self-assembly process as well as the self-assembly structures were carefully characterized by the combination methods of 1H NMR, CD, Hr-SEM, AFM, Hr-TEM, SAED pattern and EDX measurements. A hierarchical self-assembly mechanism was also proposed.As inspired from nature's strategy to prepare collagen, herein we report a hierarchical solution self-assembly method to prepare multi-dimensional and multi-scale supra-structures from the building blocks of pristine titanate nanotubes (TNTs) around 10 nm. With the help of amylose, the nanotubes was continuously self-assembled into helically wrapped TNTs, highly aligned fibres, large bundles, 2D crystal facets and 3D core-shell hybrid crystals. The amyloses work as the glue molecules to drive and direct the hierarchical self-assembly process extending from microscopic to macroscopic scale. The whole self-assembly process as well as the self-assembly structures were carefully characterized by the combination methods of 1H NMR, CD, Hr-SEM, AFM, Hr-TEM, SAED pattern and EDX measurements. A hierarchical self-assembly mechanism was also proposed. Electronic supplementary information (ESI) available: Characterization of the A/TNTs and TNT crystals. See DOI: 10.1039/c1nr11151e

  16. From nano to macro: studying the hierarchical structure of the corneal extracellular matrix.

    Science.gov (United States)

    Quantock, Andrew J; Winkler, Moritz; Parfitt, Geraint J; Young, Robert D; Brown, Donald J; Boote, Craig; Jester, James V

    2015-04-01

    In this review, we discuss current methods for studying ocular extracellular matrix (ECM) assembly from the 'nano' to the 'macro' levels of hierarchical organization. Since collagen is the major structural protein in the eye, providing mechanical strength and controlling ocular shape, the methods presented focus on understanding the molecular assembly of collagen at the nanometre level using X-ray scattering through to the millimetre to centimetre level using non-linear optical (NLO) imaging of second harmonic generated (SHG) signals. Three-dimensional analysis of ECM structure is also discussed, including electron tomography, serial block face scanning electron microscopy (SBF-SEM) and digital image reconstruction. Techniques to detect non-collagenous structural components of the ECM are also presented, and these include immunoelectron microscopy and staining with cationic dyes. Together, these various approaches are providing new insights into the structural blueprint of the ocular ECM, and in particular that of the cornea, which impacts upon our current understanding of the control of corneal shape, pathogenic mechanisms underlying ectatic disorders of the cornea and the potential for corneal tissue engineering. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Influence of Homogenization and Micro/Nano Source of Starting Powders on Format Ion of the Single YAP Phase

    Directory of Open Access Journals (Sweden)

    Michalik D.

    2016-12-01

    Full Text Available Manufacturing high purity polycrystalline YAlO3 (YAP ceramics could replace monocrystalline YAP thus recently it is an interesting task for low cost producers of scintillators. The paper presents influence of different source of initial oxide powders (micro/nano powders of Y2O3 and Al2O3 and the method of their homogenization on the formation of a YAP phase. The solid state reaction method was used to prepare YAP powder or ceramic pellets. After preheating, all samples in the form of powders and pellets were heat-treated in the temperature range of 1050-1650 °C. DTA method was applied for examination of the phase crystallization in the tested system. X-ray diffraction method (XRD was used for characterization of the phase composition. X-ray microanalysis (EDS was used to control homogeneity in the small areas. Morphology of the resultant samples are presented on SEM pictures. The results show a significant influence of the starting powders on the homogeneity, purity and temperature of formation of the main phase.

  18. Fabrication of hierarchical structures for stable superhydrophobicity on metallic planar and cylindrical inner surfaces

    Science.gov (United States)

    Hao, Xiuqing; Wang, Li; Lv, Danhui; Wang, Quandai; Li, Liang; He, Ning; Lu, Bingheng

    2015-01-01

    Recently, the construction of stable superhydrophobicity on metallic wetting surfaces has gained increasing attention due to its potential wide applications. In this paper, we propose an economic fabricating method, which not only is suitable for metallic planar surfaces, but also could be applied onto cylindrical inner surfaces. It mainly involves two steps: etching micro-concaves by a movable mask electrochemical micromachining (EMM) technique and fabricating nanopillars of ZnO by a hydrothermal method. Then the influences of surface morphology on the static and dynamic behaviors of water droplets are investigated. The energy loss during impact on the surfaces is quantified in terms of the restitution coefficient for droplets bouncing off the surfaces. For hierarchical structures with excellent superhydrophobicity (contact angle ≈180° and sliding angle ≤1°), the droplet bounces off the surface several times, superior to the droplet's response on single nanopillars (contact angle ≈165.8° and sliding angle ≈6.29°) where droplet bounces off only for limited a number of times, and even far better than the dynamics of a liquid droplet impinging on microstructures (contact angle ≈132.1° and sliding angle >90°) where droplet does not rebound and remains pinned. The highest elasticity is obtained on the hierarchical surface, where the restitution coefficient can be as large as 0.94. The fabricating method is then applied onto the cylindrical inner surface and the wetting behavior is confirmed to be consistent with the planar surface. This method, which can be generalized to any kind of solid electroconductive metal or other surfaces with different shapes, could find wide practical applications in self-cleaning surfaces, chemical industry, microfluidic devices, mechanical engineering and aviation.

  19. Motion Tree Delineates Hierarchical Structure of Protein Dynamics Observed in Molecular Dynamics Simulation.

    Directory of Open Access Journals (Sweden)

    Kei Moritsugu

    Full Text Available Molecular dynamics (MD simulations of proteins provide important information to understand their functional mechanisms, which are, however, likely to be hidden behind their complicated motions with a wide range of spatial and temporal scales. A straightforward and intuitive analysis of protein dynamics observed in MD simulation trajectories is therefore of growing significance with the large increase in both the simulation time and system size. In this study, we propose a novel description of protein motions based on the hierarchical clustering of fluctuations in the inter-atomic distances calculated from an MD trajectory, which constructs a single tree diagram, named a "Motion Tree", to determine a set of rigid-domain pairs hierarchically along with associated inter-domain fluctuations. The method was first applied to the MD trajectory of substrate-free adenylate kinase to clarify the usefulness of the Motion Tree, which illustrated a clear-cut dynamics picture of the inter-domain motions involving the ATP/AMP lid and the core domain together with the associated amplitudes and correlations. The comparison of two Motion Trees calculated from MD simulations of ligand-free and -bound glutamine binding proteins clarified changes in inherent dynamics upon ligand binding appeared in both large domains and a small loop that stabilized ligand molecule. Another application to a huge protein, a multidrug ATP binding cassette (ABC transporter, captured significant increases of fluctuations upon binding a drug molecule observed in both large scale inter-subunit motions and a motion localized at a transmembrane helix, which may be a trigger to the subsequent structural change from inward-open to outward-open states to transport the drug molecule. These applications demonstrated the capabilities of Motion Trees to provide an at-a-glance view of various sizes of functional motions inherent in the complicated MD trajectory.

  20. Biomolecule-Assisted Hydrothermal Synthesis and Self-Assembly of Bi2Te3 Nanostring-Cluster Hierarchical Structure

    DEFF Research Database (Denmark)

    Mi, Jianli; Lock, Nina; Sun, Ting;

    2010-01-01

    A simple biomolecule-assisted hydrothermal approach has been developed for the fabrication of Bi2Te3 thermoelectric nanomaterials. The product has a nanostring-cluster hierarchical structure which is composed of ordered and aligned platelet-like crystals. The platelets are100 nm in diameter...