WorldWideScience

Sample records for blocking layer

  1. Block copolymer/homopolymer dual-layer hollow fiber membranes

    KAUST Repository

    Hilke, Roland

    2014-12-01

    We manufactured the first time block copolymer dual-layer hollow fiber membranes and dual layer flat sheet membranes manufactured by double solution casting and phase inversion in water. The support porous layer was based on polystyrene and the selective layer with isopores was formed by micelle assembly of polystyrene-. b-poly-4-vinyl pyridine. The dual layers had an excellent interfacial adhesion and pore interconnectivity. The dual membranes showed pH response behavior like single layer block copolymer membranes with a low flux for pH values less than 3, a fast increase between pH4 and pH6 and a constant high flux level for pH values above 7. The dry/wet spinning process was optimized to produce dual layer hollow fiber membranes with polystyrene internal support layer and a shell block copolymer selective layer.

  2. Design of Optimal Diffusion Layers for SPN Block Ciphers

    Institute of Scientific and Technical Information of China (English)

    CUI Ling-guo; CAO Yuan-da

    2006-01-01

    The diffusion layers in substitution-permutation network(SPN) block ciphers are almost invertible linear transformations, which is optimal if the branch number reaches the maximum value. The method of constructing involutory optimal diffusion layers is proposed based on the Cauchy matrix, which can decrease the cost of implementation. The analysis to experimental results indicates that the diffusion layer ensures the security of the SPN block cipher against differential cryptanalysis(DC) and linear cryptanalysis(LC), and decreases half the cost of implementation.

  3. Optimization of fire blocking layers for aircraft seating

    Science.gov (United States)

    Parker, J. A.; Kourtides, D. A.

    1982-01-01

    Ablative materials are used to provide thermal protection for heat sensitive substrates against large jet fuel fires. The present investigation is concerned with the possibility to increase the available egress time for passengers, from a transport aircraft, in which the flexible polyurethane seating is exposed to the action of a large pool fire. Suitable approaches for providing sufficient ablative protection for polyurethane cushioning are considered. The efficiency of any fire blocking layer is defined as the ratio of the incident radiant heating rate, to the rate of production of combustible gas produced per unit area per second, generated by the pyrolysis of the substrate polyurethane foam. It is found that adequate fire blocking protection can be achieved through replacement of cotton batting slip covers with a wide variety of fire blocking layers. Metallized high temperature resistant char forming ablatives appear to provide optimum protection.

  4. Atomic layer deposition of ultrathin blocking layer for low-temperature solid oxide fuel cell on nanoporous substrate

    International Nuclear Information System (INIS)

    An ultrathin yttria-stabilized zirconia (YSZ) blocking layer deposited by atomic layer deposition (ALD) was utilized for improving the performance and reliability of low-temperature solid oxide fuel cells (SOFCs) supported by an anodic aluminum oxide substrate. Physical vapor-deposited YSZ and gadolinia-doped ceria (GDC) electrolyte layers were deposited by a sputtering method. The ultrathin ALD YSZ blocking layer was inserted between the YSZ and GDC sputtered layers. To investigate the effects of an inserted ultrathin ALD blocking layer, SOFCs with and without an ultrathin ALD blocking layer were electrochemically characterized. The open circuit voltage (1.14 V) of the ALD blocking-layered SOFC was visibly higher than that (1.05 V) of the other cell. Furthermore, the ALD blocking layer augmented the power density and improved the reproducibility

  5. Atomic layer deposition of ultrathin blocking layer for low-temperature solid oxide fuel cell on nanoporous substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wonjong; Cho, Gu Young; Noh, Seungtak; Tanveer, Waqas Hassan; Cha, Suk Won, E-mail: swcha@snu.ac.kr [School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Daehak dong, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Ji, Sanghoon [Graduate School of Convergence Science and Technology, Seoul National University, 864-1, Iui-dong, Yeongtong-gu, Suwon 443-270 (Korea, Republic of); An, Jihwan [Manufacturing Systems and Design Engineering Program, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 139-743 (Korea, Republic of)

    2015-01-15

    An ultrathin yttria-stabilized zirconia (YSZ) blocking layer deposited by atomic layer deposition (ALD) was utilized for improving the performance and reliability of low-temperature solid oxide fuel cells (SOFCs) supported by an anodic aluminum oxide substrate. Physical vapor-deposited YSZ and gadolinia-doped ceria (GDC) electrolyte layers were deposited by a sputtering method. The ultrathin ALD YSZ blocking layer was inserted between the YSZ and GDC sputtered layers. To investigate the effects of an inserted ultrathin ALD blocking layer, SOFCs with and without an ultrathin ALD blocking layer were electrochemically characterized. The open circuit voltage (1.14 V) of the ALD blocking-layered SOFC was visibly higher than that (1.05 V) of the other cell. Furthermore, the ALD blocking layer augmented the power density and improved the reproducibility.

  6. Saccharide blocking layers in solid state dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Handa, S.; Haque, S.A.; Durrant, J.R. [Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, SW7 2AZ. London (United Kingdom)

    2007-10-15

    The adsorption of saccharides on dye sensitized, nanocrystalline metal oxide films is shown to improve the efficiency of solid state dye sensitized solar cells. The function of the saccharide treatment is evaluated by transient optical studies, and correlated with device photovoltaic performance. A range of saccharides, including cyclodextrins and their linear analogue amylose, are investigated. The saccharide blocking layer is shown to retard interfacial charge recombination losses, resulting in increased device open circuit voltage. Highest device performance is achieved with linear saccharide amylose, resulting in a 60 % improvement in device efficiency relative to the non-treated control, with a device open circuit voltage of 1 V. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  7. An alternative blocking layer for titanium dioxide (TiO 2) solar cell applications

    OpenAIRE

    Memesa, M.

    2008-01-01

    In hybrid organic solar cells a blocking layer between transparent electrode and nanocrystalline titania particles is essential to prevent short-circuiting and current loss through recombination at the electrode interface. Here the preparation of a uniform hybrid blocking layer which is composed of conducting titania nanoparticles embedded in an insulating polymer derived ceramic is presented. This blocking layer is prepared by sol-gel chemistry where an amphiphilic block copolymer is use...

  8. Organic Light-Emitting Devices with a LiF Hole Blocking Layer

    Institute of Scientific and Technical Information of China (English)

    LIAN Jia-Rong; YUAN Yong-Bo; ZHOU Xiang

    2007-01-01

    We introduce a thin LiF layer into tris-8-hydroxyquinoline aluminium (Alq3) based bilayer organic light-emittingdevices to block hole transport. By varying the thickness and position of this LiF layer in Alq3, we obtain an electroluminescent efficiency increase by a factor of two with respect to the control devices without a LiF blocking layer. By using a 10nm dye doped Alq3 sensor layer, we prove that LiF can block holes and excitons effectively.Experimental results suggest that the thin LiF layer may be a good hole and exciton blocking layer.

  9. pH-responsive layer-by-layer films of zwitterionic block copolymer micelles

    OpenAIRE

    Demirel, Adem Levent; Yusan, Pelin; Tuncel, İrem; Bütün, Vural; Erel-Goktepe, İrem

    2014-01-01

    We report a strategy to incorporate micelles of poly[3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate]-block-poly[2-(diisopropylamino) ethyl methacrylate] (beta PDMA-b-PDPA) into electrostatic layer-by-layer (LbL) films. We obtained micelles with pH-responsive PDPA-cores and zwitterionic bPDMA-coronae at pH 8.5 through pH-induced self-assembly of bPDMA-b-PDPA in aqueous solution. To incorporate bPDMA-b-PDPA micelles into LbL films, we first obtained a net electrical charge on bPDM...

  10. Enhancement of efficiency of multilayer polymer light-emitting diodes by inserting blocking layers

    International Nuclear Information System (INIS)

    In this study, the electroluminescence efficiency of the blue-green polymer light-emitting diodes (PLEDs) is enhanced by the insertion of blocking layers. PLEDs are multilayered structures prepared with spin-coating and thermal evaporation. Blue host is doped with green guest to form a single emission layer. Poly(9-vinylcarbazole) (PVK) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) are used as materials for the blocking layers. The optimal thicknesses of the PVK and BCP layers are 10 and 0.2 nm, respectively. PVK plays an important role of blocking holes and electrons, and BCP not only confines holes in the emission layer but also enhances the injection of electrons from Alq3 to the emission layer. The efficiency of a PLED with a dual-blocking layer is 2.37 times higher than that of a PLED without a blocking layer prepared because of the improved carrier balance and the enhanced carrier recombination. - Research highlights: → Multilayered structures have been developed for improving the efficiency of OLED. → Insertion of blocking layers is one of the effective methods for enhancing the efficiency of OLEDs. → For a PLED, it is hard to find a solvent which is immiscible with the material of the bottom layer. → In this study, multilayer PLEDs were fabricated by spin-coating and thermal evaporation. → The efficiency of a PLED with a dual-blocking layer is increased by 2.37 times.

  11. Organic photosensitive cells having a reciprocal-carrier exciton blocking layer

    Science.gov (United States)

    Rand, Barry P.; Forrest, Stephen R.; Thompson, Mark E.

    2007-06-12

    A photosensitive cell includes an anode and a cathode; a donor-type organic material and an acceptor-type organic material forming a donor-acceptor junction connected between the anode and the cathode; and an exciton blocking layer connected between the acceptor-type organic material of the donor-acceptor junction and the cathode, the blocking layer consisting essentially of a material that has a hole mobility of at least 10.sup.-7 cm.sup.2/V-sec or higher, where a HOMO of the blocking layer is higher than or equal to a HOMO of the acceptor-type material.

  12. Electrochemical Characterization of TiO 2 Blocking Layers for Dye-Sensitized Solar Cells

    KAUST Repository

    Kavan, Ladislav

    2014-07-31

    Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from the substrate (FTO or Ti) with the hole-conducting medium at this interface. The quality of blocking is evaluated electrochemically by methylviologen, ferro/ferricyanide, and spiro-OMeTAD as the model redox probes. Two types of pinholes in the blocking layers are classified, and their effective area is quantified. Frequency-independent Mott-Schottky plots are fitted from electrochemical impedance spectroscopy. Certain films of the thicknesses of several nanometers allow distinguishing the depletion layer formation both in the TiO2 film and in the FTO substrate underneath the titania film. The excellent blocking function of thermally oxidized Ti, electrodeposited film (60 nm), and atomic-layer-deposited films (>6 nm) is documented by the relative pinhole area of less than 1%. However, the blocking behavior of electrodeposited and atomic-layer-deposited films is strongly reduced upon calcination at 500 °C. The blocking function of spray-pyrolyzed films is less good but also less sensitive to calcination. The thermally oxidized Ti is well blocking and insensitive to calcination. © 2014 American Chemical Society.

  13. Improved performance of P-type DSCs with a compact blocking layer coated by different thicknesses

    Science.gov (United States)

    Ho, Phuong; Bao, Le Quoc; Cheruku, Rajesh; Kim, Jae Hong

    2016-09-01

    The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells ( p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency ( η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

  14. Application of a hybrid blocking layer in dye-sensitized solar cells

    OpenAIRE

    Lellig, P.

    2011-01-01

    In dye-sensitized solar cells a blocking layer between the transparent electrode and the mesoporous titanium dioxide film is used to prevent short-circuits between the hole-conductor and the front electrode. The conventional approach is to use a compact layer of titanium dioxide prepared by spin coating or spray pyrolysis. The thickness of the blocking layer is critical. On one hand, the layer has to be thick enough to cover the rough substrate completely. On the other hand, the serial resist...

  15. Blocking force of a piezoelectric stack actuator made of single crystal layers (PMN-29PT)

    Science.gov (United States)

    Tran, K. S.; Phan, H. V.; Lee, H. Y.; Kim, Yongdae; Park, H. C.

    2016-09-01

    In this study, we fabricated and characterized a stack actuator made of forty layers of 1 mm thick PMN-29PT with a cross-sectional area of 10 × 10 mm2. From the measurement of actuation displacement, we confirmed that the piezoelectric strain constant in the direction of thickness of the material is 2000 pm V-1, as suggested by the manufacturer. The blocking forces of the actuator are measured to be 230 N, 369 N, and 478 N for 100 V, 200 V, and 300 V, respectively. The measured blocking forces showed large discrepancies from the estimated blocking forces calculated using linear models, especially for a high voltage application. An empirical equation acquired by fitting the measured blocking forces indicates that the blocking force has a nonlinear relationship with the applied voltage. The measured hysteresis showed a slight nonlinear voltage-stroke relationship and small energy loss.

  16. Blocking force of a piezoelectric stack actuator made of single crystal layers (PMN-29PT)

    Science.gov (United States)

    Tran, K. S.; Phan, H. V.; Lee, H. Y.; Kim, Yongdae; Park, H. C.

    2016-09-01

    In this study, we fabricated and characterized a stack actuator made of forty layers of 1 mm thick PMN-29PT with a cross-sectional area of 10 × 10 mm2. From the measurement of actuation displacement, we confirmed that the piezoelectric strain constant in the direction of thickness of the material is 2000 pm V‑1, as suggested by the manufacturer. The blocking forces of the actuator are measured to be 230 N, 369 N, and 478 N for 100 V, 200 V, and 300 V, respectively. The measured blocking forces showed large discrepancies from the estimated blocking forces calculated using linear models, especially for a high voltage application. An empirical equation acquired by fitting the measured blocking forces indicates that the blocking force has a nonlinear relationship with the applied voltage. The measured hysteresis showed a slight nonlinear voltage-stroke relationship and small energy loss.

  17. Improved performance of InGaN light-emitting diodes with a novel sawtooth-shaped electron blocking layer

    Institute of Scientific and Technical Information of China (English)

    Wang Tian-Hu; Xu Jin-Liang

    2013-01-01

    A sawtooth-shaped electron blocking layer is proposed to improve the performance of light-emitting diodes (LEDs).The energy band diagram,the electrostatic field in the quantum well,the carrier concentration,the electron leakage,and the internal quantum efficiency are systematically studied.The simulation results show that the LED with a sawtooth-shaped electron blocking layer possesses higher output power and a smaller efficiency droop than the LED with a conventional A1GaN electron blocking layer,which is because the electron confinement is enhanced and the hole injection efficiency is improved by the appropriately modified electron blocking layer energy band.

  18. Enhanced JPEG2000 Quality Scalability through Block-Wise Layer Truncation

    Directory of Open Access Journals (Sweden)

    Auli-Llinas Francesc

    2010-01-01

    Full Text Available Quality scalability is an important feature of image and video coding systems. In JPEG2000, quality scalability is achieved through the use of quality layers that are formed in the encoder through rate-distortion optimization techniques. Quality layers provide optimal rate-distortion representations of the image when the codestream is transmitted and/or decoded at layer boundaries. Nonetheless, applications such as interactive image transmission, video streaming, or transcoding demand layer fragmentation. The common approach to truncate layers is to keep the initial prefix of the to-be-truncated layer, which may greatly penalize the quality of decoded images, especially when the layer allocation is inadequate. So far, only one method has been proposed in the literature providing enhanced quality scalability for compressed JPEG2000 imagery. However, that method provides quality scalability at the expense of high computational costs, which prevents its application to the aforementioned applications. This paper introduces a Block-Wise Layer Truncation (BWLT that, requiring negligible computational costs, enhances the quality scalability of compressed JPEG2000 images. The main insight behind BWLT is to dismantle and reassemble the to-be-fragmented layer by selecting the most relevant codestream segments of codeblocks within that layer. The selection process is conceived from a rate-distortion model that finely estimates rate-distortion contributions of codeblocks. Experimental results suggest that BWLT achieves near-optimal performance even when the codestream contains a single quality layer.

  19. Adaptive Multi-Layered Space-Time Block Coded Systems in Wireless Environments

    KAUST Repository

    Al-Ghadhban, Samir

    2014-12-23

    © 2014, Springer Science+Business Media New York. Multi-layered space-time block coded systems (MLSTBC) strike a balance between spatial multiplexing and transmit diversity. In this paper, we analyze the block error rate performance of MLSTBC. In addition, we propose an adaptive MLSTBC schemes that are capable of accommodating the channel signal-to-noise ratio variation of wireless systems by near instantaneously adapting the uplink transmission configuration. The main results demonstrate that significant effective throughput improvements can be achieved while maintaining a certain target bit error rate.

  20. Novel layered two-dimensional semiconductors as the building blocks for nano-electronic/photonic systems

    Science.gov (United States)

    Su, Guoxiong; De, Debtanu; Hadjiev, Viktor G.; Peng, Haibing

    2014-06-01

    Layered two-dimensional (2D) semiconductors beyond graphene have been emerging as potential building blocks for the next-generation electronic/photonic applications. Representative metal chalcogenides, including the widely studied MoS2, possess similar layered crystal structures with weak interaction between adjacent layers, thus allowing the formation of stable thin-layer crystals with thickness down to a few or even single atomic layer. Other important chalcogenides, involving earth-abundant and environment-friendly materials desirable for sustainable applications, include SnS2 (band gap: 2.1 eV) and SnS (band gap: 1.1 eV). So far, commonly adopted for research purpose are mechanical and liquid exfoliation methods for creating thin layers of such 2D semiconductors. Most recently, chemical vapor deposition (CVD) was attracting significant attention as a practical method for producing thin films or crystal grains of MoS2. However, critical yet still absent is an effective experimental approach for controlling the positions of thin crystal grains of layered 2D semiconductors during the CVD process. Here we report the controlled CVD synthesis of thin crystal arrays of representative layered semiconductors (including SnS2 and SnS) at designed locations on chip, promising large-scale optoelectronic applications. Our work opens a window for future practical applications of layered 2D semiconductors in integrated nano-electronic/photonic systems.

  1. Balancing high gain and bandwidth in multilayer organic photodetectors with tailored carrier blocking layers

    International Nuclear Information System (INIS)

    We present detailed studies of the high photocurrent gain behavior in multilayer organic photodiodes containing tailored carrier blocking layers we reported earlier in a Letter [W. T. Hammond and J. Xue, Appl. Phys. Lett. 97, 073302 (2010)], in which a high photocurrent gain of up to 500 was attributed to the accumulation of photogenerated holes at the anode/organic active layer interface and the subsequent drastic increase in secondary electron injection from the anode. Here, we show that both the hole-blocking layer structure and layer thickness strongly influence the magnitude of the photocurrent gain. Temporal studies revealed that the frequency response of such devices is limited by three different processes with lifetimes of 10 μs, 202 μs, and 2.72 ms for the removal of confined holes, which limit the 3 dB bandwidth of these devices to 1.4 kHz. Furthermore, the composition in the mixed organic donor-acceptor photoactive layer affects both gain and bandwidth, which is attributed to the varying charge transport characteristics, and the optimal gain-bandwidth product is achieved with approximately 30% donor content. Finally, these devices show a high dynamic range of more than seven orders of magnitude, although the photocurrent shows a sublinear dependence on the incident optical power

  2. Effect of substrate composition on atomic layer deposition using self-assembled monolayers as blocking layers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenyu; Engstrom, James R., E-mail: jre7@cornell.edu [School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2016-01-15

    The authors have examined the effect of two molecules that form self-assembled monolayers (SAMs) on the subsequent growth of TaN{sub x} by atomic layer deposition (ALD) on two substrate surfaces, SiO{sub 2} and Cu. The SAMs that the authors have investigated include two vapor phase deposited, fluorinated alkyl silanes: Cl{sub 3}Si(CH{sub 2}){sub 2}(CF{sub 2}){sub 5}CF{sub 3} (FOTS) and (C{sub 2}H{sub 5}O){sub 3}Si(CH{sub 2}){sub 2}(CF{sub 2}){sub 7}CF{sub 3} (HDFTEOS). Both the SAMs themselves and the TaN{sub x} thin films, grown using Ta[N(CH{sub 3}){sub 2}]{sub 5} and NH{sub 3}, were analyzed ex situ using contact angle, spectroscopic ellipsometry, x-ray photoelectron spectroscopy (XPS), and low energy ion-scattering spectroscopy (LEISS). First, the authors find that both SAMs on SiO{sub 2} are nominally stable at T{sub s} ∼ 300 °C, the substrate temperature used for ALD, while on Cu, the authors find that HDFTEOS thermally desorbs, while FOTS is retained on the surface. The latter result reflects the difference in the head groups of these two molecules. The authors find that both SAMs strongly attenuate the ALD growth of TaN{sub x} on SiO{sub 2}, by about a factor of 10, while on Cu, the SAMs have no effect on ALD growth. Results from LEISS and XPS are decisive in determining the nature of the mechanism of growth of TaN{sub x} on all surfaces. Growth on SiO{sub 2} is 2D and approximately layer-by-layer, while on the surfaces terminated by the SAMs, it nucleates at defect sites, is islanded, and is 3D. In the latter case, our results support growth of the TaN{sub x} thin film over the SAM, with a considerable delay in formation of a continuous thin film. Growth on Cu, with or without the SAMs, is also 3D and islanded, and there is also a delay in the formation of a continuous thin film as compared to growth on SiO{sub 2}. These results highlight the power of coupling measurements from both LEISS and XPS in examinations of ultrathin films formed by ALD.

  3. The effect of a thin weak layer covering a basalt block on the impact cratering process

    Science.gov (United States)

    Dohi, Koji; Arakawa, Masahiko; Okamoto, Chisato; Hasegawa, Sunao; Yasui, Minami

    2012-04-01

    To clarify the effect of a surface regolith layer on the formation of craters in bedrock, we conducted impact-cratering experiments on two-layered targets composed of a basalt block covered with a mortar layer. A nylon projectile was impacted on the targets at velocities of 2 and 4 km s-1, and we investigated the crater size formed on the basalt. The crater size decreased with increased mortar thickness and decreased projectile mass and impact velocity. The normalized crater volume, πV, of all the data was successfully scaled by the following exponential equation with a reduction length λ0: π=b0πY-b1exp(-λ/λ0), where λ is the normalized thickness T/Lp, T and Lp are the mortar thickness and the projectile length, respectively, b0 and b1 are fitted parameters obtained for a homogeneous basalt target, 10-2.7±0.7 and -1.4 ± 0.3, respectively, and λ0 is obtained to be 0.38 ± 0.03. This empirical equation showing the effect of the mortar layer was physically explained by an improved non-dimensional scaling parameter, πY∗, defined by πY∗=Y/(ρup2), where up was the particle velocity of the mortar layer at the boundary between the mortar and the basalt. We performed the impact experiments to obtain the attenuation rate of the particle velocity in the mortar layer and derived the empirical equation of {u}/{v}=0.50exp-{λ}/{1.03}, where vi is the impact velocity of the projectile. We propose a simple model for the crater formation on the basalt block that the surface mortar layer with the impact velocity of up collides on the surface of the basalt block, and we confirmed that this model could reproduce our empirical equation showing the effect of the surface layer on the crater volume of basalt.

  4. Effect of TiO2 blocking layer on TiO2 nanorod arrays based dye sensitized solar cells

    Science.gov (United States)

    Sivakumar, R.; Paulraj, M.

    2016-05-01

    Highly ordered rutile titanium dioxide nanorod (TNR) arrays (1.2 to 6.2 μm thickness) were grown on TiO2 blocking layer chemically deposited on fluorine doped tin oxide (FTO) substrate and were used as photo-electrodes to fabricate dye sensitized solar cells (DSSC's). Homogeneous layer of TiO2 on FTO was achieved by using aqueous peroxo- titanium complex (PTC) solutions via chemical bath deposition. Structural and morphological properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) measurements. TNR arrays (6.2 μm) with TiO2 blocking layer showed higher energy conversion efficiency (1.46%) than that without TiO2 blocking layer. The reason can be ascertained to the suppression of electron-hole recombination at the semiconductor/electrolyte interface by the effect of TiO2 blocking layer.

  5. Study of carrier blocking property of poly-linalyl acetate thin layer by electric-field-induced optical second-harmonic generation measurement

    Science.gov (United States)

    Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Anderson, Liam J.; Jacob, Mohan V.

    2014-02-01

    By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the carrier-blocking property of poly-linalyl acetate (PLA) thin layers sandwiched in indium-zinc-oxide (IZO)/PLA/C60/Al double-layer diodes. Results showed that the PLA layer totally blocks electrons crossing the C60 layer, and also blocks holes entering from the IZO layer. The EFISHG measurement effectively substantiates the hole-blocking electron-blocking property of the PLA layer sandwiched in double layer diodes.

  6. Block Copolymer-Tuned Fullerene Electron Transport Layer Enhances the Efficiency of Perovskite Photovoltaics.

    Science.gov (United States)

    Lin, Hsi-Kuei; Su, Yu-Wei; Chen, Hsiu-Cheng; Huang, Yi-Jiun; Wei, Kung-Hwa

    2016-09-21

    In this study, we enhanced the power conversion efficiency (PCE) of perovskite solar cells by employing an electron transfer layer (ETL) comprising [6,6]phenyl-C61-butyric acid methyl ester (PC61BM) and, to optimize its morphology, a small amount of the block copolymer polystyrene-b-poly(ethylene oxide) (PS-b-PEO), positioned on the perovskite active layer. When incorporating 0.375 wt % PS-b-PEO into PC61BM, the PCE of the perovskite photovoltaic device increased from 9.4% to 13.4%, a relative increase of 43%, because of a large enhancement in the fill factor of the device. To decipher the intricate morphology of the ETL, we used synchrotron grazing-incidence small-angle X-ray scattering for determining the PC61BM cluster size, atomic force microscopy and scanning electron microscopy for probing the surface, and transmission electron microscopy for observing the aggregation of PC61BM in the ETL. We found that the interaction between PS-b-PEO and PC61BM resulted in smaller PC61BM clusters that further aggregated into dendritic structures in some domains, a result of the similar polarities of the PS block and PC61BM; this behavior could be used to tune the morphology of the ETL. The optimal PS-b-PEO-mediated PC61BM cluster size in the ETL was 17 nm, a large reduction from 59 nm for the pristine PC61BM layer. This approach of incorporating a small amount of nanostructured block copolymer into a fullerene allowed us to effectively tune the morphology of the ETL on the perovskite active layer and resulted in enhanced fill factors of the devices and thus their device efficiency.

  7. Block Copolymer-Tuned Fullerene Electron Transport Layer Enhances the Efficiency of Perovskite Photovoltaics.

    Science.gov (United States)

    Lin, Hsi-Kuei; Su, Yu-Wei; Chen, Hsiu-Cheng; Huang, Yi-Jiun; Wei, Kung-Hwa

    2016-09-21

    In this study, we enhanced the power conversion efficiency (PCE) of perovskite solar cells by employing an electron transfer layer (ETL) comprising [6,6]phenyl-C61-butyric acid methyl ester (PC61BM) and, to optimize its morphology, a small amount of the block copolymer polystyrene-b-poly(ethylene oxide) (PS-b-PEO), positioned on the perovskite active layer. When incorporating 0.375 wt % PS-b-PEO into PC61BM, the PCE of the perovskite photovoltaic device increased from 9.4% to 13.4%, a relative increase of 43%, because of a large enhancement in the fill factor of the device. To decipher the intricate morphology of the ETL, we used synchrotron grazing-incidence small-angle X-ray scattering for determining the PC61BM cluster size, atomic force microscopy and scanning electron microscopy for probing the surface, and transmission electron microscopy for observing the aggregation of PC61BM in the ETL. We found that the interaction between PS-b-PEO and PC61BM resulted in smaller PC61BM clusters that further aggregated into dendritic structures in some domains, a result of the similar polarities of the PS block and PC61BM; this behavior could be used to tune the morphology of the ETL. The optimal PS-b-PEO-mediated PC61BM cluster size in the ETL was 17 nm, a large reduction from 59 nm for the pristine PC61BM layer. This approach of incorporating a small amount of nanostructured block copolymer into a fullerene allowed us to effectively tune the morphology of the ETL on the perovskite active layer and resulted in enhanced fill factors of the devices and thus their device efficiency. PMID:27574718

  8. Neutral wetting brush layers for block copolymer thin films using homopolymer blends processed at high temperatures.

    Science.gov (United States)

    Ceresoli, M; Palermo, M; Ferrarese Lupi, F; Seguini, G; Perego, M; Zuccheri, G; Phadatare, S D; Antonioli, D; Gianotti, V; Sparnacci, K; Laus, M

    2015-10-16

    Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacrylate (PMMA-OH) homopolymers (Mn ∼ 16000 g mol(-1)) were grafted on SiO2 substrates by high-temperature (T > 150 °C), short-time (t layer was tested to screen preferential interactions of the SiO2 substrate with the different symmetric and asymmetric PS-b-PMMA block copolymers deposited on top of the grafted molecules. By properly adjusting the blend composition and the processing parameters, an efficient surface neutralization path was identified, enabling the formation, in the block copolymer film, of homogeneous textures of lamellae or cylinders perpendicularly oriented with respect to the substrate. A critical interplay between the phase segregation of the homopolymer blends and their grafting process on the SiO2 was observed. In fact, the polar SiO2 is preferential for the PMMA-rich phase that forms a homogeneous layer on the substrate, while the PS-rich phase is located at the polymer-air interface. During the thermal treatment, phase segregation and grafting proceed simultaneously. Complete wetting of the PS rich phase on the PMMA rich phase leads to the formation of a PS/PMMA bilayer. In this case, the progressive diffusion of PS chains toward the polymer-SiO2 interface during the thermal treatment allows tuning of the brush layer composition.

  9. Laser Writing Block Copolymer Self-Assembly on Graphene Light-Absorbing Layer.

    Science.gov (United States)

    Jin, Hyeong Min; Lee, Seung Hyun; Kim, Ju Young; Son, Seung-Woo; Kim, Bong Hoon; Lee, Hwan Keon; Mun, Jeong Ho; Cha, Seung Keun; Kim, Jun Soo; Nealey, Paul F; Lee, Keon Jae; Kim, Sang Ouk

    2016-03-22

    Recent advance of high-power laser processing allows for rapid, continuous, area-selective material fabrication, typically represented by laser crystallization of silicon or oxides for display applications. Two-dimensional materials such as graphene exhibit remarkable physical properties and are under intensive development for the manufacture of flexible devices. Here we demonstrate an area-selective ultrafast nanofabrication method using low intensity infrared or visible laser irradiation to direct the self-assembly of block copolymer films into highly ordered manufacturing-relevant architectures at the scale below 12 nm. The fundamental principles underlying this light-induced nanofabrication mechanism include the self-assembly of block copolymers to proceed across the disorder-order transition under large thermal gradients, and the use of chemically modified graphene films as a flexible and conformal light-absorbing layers for transparent, nonplanar, and mechanically flexible surfaces.

  10. Laser Writing Block Copolymer Self-Assembly on Graphene Light-Absorbing Layer.

    Science.gov (United States)

    Jin, Hyeong Min; Lee, Seung Hyun; Kim, Ju Young; Son, Seung-Woo; Kim, Bong Hoon; Lee, Hwan Keon; Mun, Jeong Ho; Cha, Seung Keun; Kim, Jun Soo; Nealey, Paul F; Lee, Keon Jae; Kim, Sang Ouk

    2016-03-22

    Recent advance of high-power laser processing allows for rapid, continuous, area-selective material fabrication, typically represented by laser crystallization of silicon or oxides for display applications. Two-dimensional materials such as graphene exhibit remarkable physical properties and are under intensive development for the manufacture of flexible devices. Here we demonstrate an area-selective ultrafast nanofabrication method using low intensity infrared or visible laser irradiation to direct the self-assembly of block copolymer films into highly ordered manufacturing-relevant architectures at the scale below 12 nm. The fundamental principles underlying this light-induced nanofabrication mechanism include the self-assembly of block copolymers to proceed across the disorder-order transition under large thermal gradients, and the use of chemically modified graphene films as a flexible and conformal light-absorbing layers for transparent, nonplanar, and mechanically flexible surfaces. PMID:26871736

  11. Effect of Vertical Vibration on Block Foundation Resting on Homogeneous and Layered Medium

    Directory of Open Access Journals (Sweden)

    Ankesh Kumar1 , Dr. Bappaditya Manna2 , Prof. K. S. Rao3

    2013-10-01

    Full Text Available In the present study, an investigation is carried out to determine the effect of soil–rock and rock–rock foundation systems on dynamic response of block foundations under vertical mode of vibration. The half-space theory is used for the analysis of foundation resting on homogeneous soil and rocks. The finite element program having transmitting boundaries is considered for layered system considering soil–rock and rock–rock combinations. The analysis is carried out in details for soil– rock and weathered rock–rock systems and the different equations are presented for above combinations. The effect of top layer thicknesses, shear wave velocity and eccentric moments are also simulated. The rock–rock systems considered are sandstone, shale and limestone underlain by basalt rock. It is interpreted that as the shear wave velocity ratio increase the natural frequency increases and the peak displacement amplitude decreases.

  12. Numerical simulation of top-emitting organic light-emitting diodes with electron and hole blocking layers

    Science.gov (United States)

    Chang, Shu-Hsuan; Yang, Cheng-Hong

    2007-09-01

    The few reported high-contrast organic light-emitting diodes (OLEDs) all deal with bottom-emitting OLEDs and may not be readily adapted for top-emitting OLEDs (TOLEDs), which have a few technical merits over bottom-emitting devices for high-performance active-matrix OLED displays (AMOLEDs). The thin-film transistors on the back-plane of an AM substrate reduce the aperture ratio of a pixel that decreases the display brightness. A TOLED, which can provide a more flexible pixel design on an opaque AM substrate, represents a promising technique for achieving a high aperture-ratio AMOLED. In this work, the characteristics of TOLEDs with α-NPD and LiF blocking layers are numerically investigated with the APSYS simulation program. The α-NPD layer is used as an electron blocking layer, while the LiF layer is used as a hole blocking layer. The TOLED structure used in this study is based on a real device fabricated in lab by Yang et al. (Appl. Phys. Lett. 87, 143507, 2005). The simulation results indicate that when the TOLED device is with either α-NPD or LiF blocking layer, the luminance efficiency and radiative recombination rate at the same drive voltage can be markedly improved. The TOLED with α-NPD blocking layer has the best performance when the position of light emission is located at the anti-node of the standing wave due to micro-cavity effect. The TOLED with LiF blocking layer has improved performance because the LUMO of Alq 3 can be lowered by band bending, which leads to better carrier balance and thus increased radiative recombination rate.

  13. EUV transmission of Optical Blocking Filter and Optical Blocking Layer for Soft X-ray Imager (SXI) onboard Astro-H

    OpenAIRE

    渡辺, 辰雄; Watanabe, Tatsuo; 幸村, 孝由; Kohmura, Takayoshi; 北本, 俊二; Kitamoto, Shunji; 村上, 弘志; Murakami, Hiroshi; 竹中, 恵理; Takenaka, Eri; 長崎, 健太; Nagasaki, Kenta; 東, 慶一; Higashi, Keiichi; 吉田, 正樹

    2010-01-01

    We have developed the X-ray CCD camera system for the Soft X-ray Imager (SXI) which will be launched as focal plane detectors of X-ray telescope onboard the Japanese 6th X-ray astronomical satellite, Astro-H. The X-ray CCD is back-illuminated (BI) CCD which has an Optical Blocking Layer (OBL) directly coating its X-ray illumination surface with Aluminum-Polyimide-Aluminum instead of Optical Blocking Filter (OBF). The X-ray CCD is affected by large doses of extreme ultraviolet (EUV) radiation ...

  14. Electrodeposited Ultrathin TiO2 Blocking Layers for Efficient Perovskite Solar Cells

    Science.gov (United States)

    Su, Tzu-Sen; Hsieh, Tsung-Yu; Hong, Cheng-You; Wei, Tzu-Chien

    2015-11-01

    In this study, the electrodeposition (ED) of ultrathin, compact TiO2 blocking layers (BLs) on fluorine-doped tin oxide (FTO) glass for perovskite solar cells (PSCs) is evaluated. This bottom-up method allows for controlling the morphology and thickness of TiO2 films by simply manipulating deposition conditions. Compared with BLs produced using the spin-coating (SC) method, BLs produced using ED exhibit satisfactory surface coverage, even with a film thickness of 29 nm. Evidence from cyclic voltammetry shows that an ED BL suppresses interfacial recombination more profoundly than an SC BL does, consequently improving the photovoltaic properties of the PSC significantly. A PSC equipped with an ED TiO2 BL having a 13.6% power conversion efficiency is demonstrated.

  15. Seismic motion in urban sites consisting of blocks in welded contact with a soft layer overlying a hard half space: I. Finite set of blocks

    CERN Document Server

    Groby, J P; Groby, Jean-Philippe; Wirgin, Armand

    2006-01-01

    We address the problem of the response to a seismic wave of an urban site consisting of $N$ non-identical, non-equispaced blocks overlying a soft layer underlain by a hard substratum. The results of a theoretical analysis, appealing to a space-frequency mode-matching (MM) technique, are compared to those obtained by a space-time finite element (FE) technique. The two methods are shown to give rise to the same prediction of the seismic response for N=1 and N=2 blocks. The mechanism of the interaction between blocks and the ground, as well as that of the mutual interaction between blocks, are studied. It is shown that the presence of a small number of blocks modifies the seismic disturbance in a manner which evokes qualitatively, but not quantitatively, what was observed during the 1985 Michoacan earthquake in Mexico City. Disturbances at a much greater level, induced by a large number of blocks (in fact, a periodic set) are studied in the companion paper.

  16. Multifunctional Nitrogen-Doped Loofah Sponge Carbon Blocking Layer for High-Performance Rechargeable Lithium Batteries.

    Science.gov (United States)

    Gu, Xingxing; Tong, Chuan-Jia; Rehman, Sarish; Liu, Li-Min; Hou, Yanglong; Zhang, Shanqing

    2016-06-29

    Low-cost, long-life, and high-performance lithium batteries not only provide an economically viable power source to electric vehicles and smart electricity grids but also address the issues of the energy shortage and environmental sustainability. Herein, low-cost, hierarchically porous, and nitrogen-doped loofah sponge carbon (N-LSC) derived from the loofah sponge has been synthesized via a simple calcining process and then applied as a multifunctional blocking layer for Li-S, Li-Se, and Li-I2 batteries. As a result of the ultrahigh specific area (2551.06 m(2) g(-1)), high porosity (1.75 cm(3) g(-1)), high conductivity (1170 S m(-1)), and heteroatoms doping of N-LSC, the resultant Li-S, Li-Se, and Li-I2 batteries with the N-LSC-900 membrane deliver outstanding electrochemical performance stability in all cases, i.e., high reversible capacities of 623.6 mA h g(-1) at 1675 mA g(-1) after 500 cycles, 350 mA h g(-1) at 1356 mA g(-1) after 1000 cycles, and 150 mA h g(-1) at 10550 mA g(-1) after 5000 cycles, respectively. The successful application to Li-S, Li-Se, and Li-I2 batteries suggests that loofa sponge carbon could play a vital role in modern rechargeable battery industries as a universal, cost-effective, environmentally friendly, and high-performance blocking layer. PMID:27250732

  17. Neutral wetting brush layers for block copolymer thin films using homopolymer blends

    Science.gov (United States)

    Antonioli, Diego; Sparnacci, Katia; Laus, Michele; Lupi, Federico Ferrarese; Giammaria, Tommaso Jacopo; Seguini, Gabriele; Ceresoli, Monica; Perego, Michele; Gianotti, Valentina

    2016-05-01

    Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacrylate (PMMA-OH) homopolymers (Mn ~ 16000 g mol-1) were grafted on SiO2 substrates by high-temperature (T > 150 °C), short-time (t blend composition and the processing parameters, an efficient surface neutralization path was identified, enabling the formation, in the block copolymer film, of homogeneous textures of lamellae or cylinders perpendicularly oriented with respect to the substrate. A critical interplay between the phase segregation of the homopolymer blends and their grafting process on the SiO2 was observed. In fact, the polar SiO2 is preferential for the PMMA-rich phase that forms a homogeneous layer on the substrate, while the PS-rich phase is located at the polymer-air interface. During the thermal treatment, phase segregation and grafting proceed simultaneously. Complete wetting of the PS rich phase on the PMMA rich phase leads to the formation of a PS/PMMA bilayer. In this case, the progressive diffusion of PS chains toward the polymer-SiO2 interface during the thermal treatment allows tuning of the brush layer composition

  18. A Study on Field Emission Characteristics of Planar Graphene Layers Obtained from a Highly Oriented Pyrolyzed Graphite Block.

    KAUST Repository

    Lee, Seok Woo

    2009-07-12

    This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene layers were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed on an insulating substrate, with the resulting field emission behavior investigated using a nanomanipulator operating inside a scanning electron microscope. A pair of tungsten tips controlled by the nanomanipulator enabled electric connection with the graphene layers without postfabrication. The maximum emitted current from the graphene layers was 170 nA and the turn-on voltage was 12.1 V.

  19. The fabrication of tunable nanoporous oxide surfaces by block copolymer lithography and atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Andreozzi, A; Lamagna, L; Seguini, G; Fanciulli, M; Perego, M [Laboratorio MDM, IMM-CNR, Via C Olivetti 2, I-20864 Agrate Brianza (Italy); Schamm-Chardon, S; Castro, C, E-mail: andrea.andreozzi@mdm.imm.cnr.it [CEMES-CNRS and Universite de Toulouse, nMat group, BP 94345, F-31055 Toulouse Cedex 4 (France)

    2011-08-19

    Patterned nanoscale materials with controllable characteristic feature sizes and periodicity are of considerable interest in a wide range of fields, with various possible applications ranging from biomedical to nanoelectronic devices. Block-copolymer (BC)-based lithography is a powerful tool for the fabrication of uniform, densely spaced nanometer-scale features over large areas. Following this bottom-up approach, nanoporous polymeric films can be deposited on any type of substrate. The nanoporous periodic template can be transferred to the underlying substrate by dry anisotropic etching. Nevertheless the physical sizes of the polymeric mask represent an important limitation in the implementation of suitable lithographic protocols based on BC technology, since the diameter and the center-to-center distance of the pores cannot be varied independently in this class of materials. This problem could be overcome by combining block copolymer technology with atomic layer deposition (ALD): by means of BC-based lithography a nanoporous SiO{sub 2} template, with well-reproducible characteristic dimensions, can be fabricated and subsequently used as a backbone for the growth of perfectly conformal thin oxide films by ALD. In this work polystyrene-b-poly(methylmethacrylate) (PS-b-PMMA) BC and reactive ion etching are used to fabricate hexagonally packed 23 nm wide nanopores in a 50 nm thick SiO{sub 2} matrix. By ALD deposition of Al{sub 2}O{sub 3} thin films onto the nanoporous SiO{sub 2} templates, nanostructured Al{sub 2}O{sub 3} surfaces are obtained. By properly adjusting the thickness of the Al{sub 2}O{sub 3} film the dimension of the pores in the oxide films is progressively reduced, with nanometer precision, from the original size down to complete filling of the pores, thus providing a simple and fast strategy for the fabrication of nanoporous Al{sub 2}O{sub 3} surfaces with well-controllable feature size.

  20. Enhancement of photoconversion efficiency in dye-sensitized solar cells exploiting pulsed laser deposited niobium pentoxide blocking layers

    International Nuclear Information System (INIS)

    Among all the photovoltaic technologies developed so far, dye-sensitized solar cells are considered as a promising alternative to the expensive and environmentally unfriendly crystalline silicon-based solar cells. One of the possible strategies employed to increase their photovoltaic efficiency is to reduce the charge recombination at the cell conductive substrate through the use of a compact blocking layer. In this paper, we report on the fabrication and characterization of dye-sensitized solar cells employing niobium pentoxide (Nb2O5) thin film blocking layer deposited through the pulsed laser deposition technique on conductive substrates. The careful selection of the optimal film thickness led to a 30% enhancement of the photoconversion efficiency with respect to reference cells fabricated without blocking layer. Open circuit voltage decay and electrochemical impedance spectroscopy techniques proved that the effective suppression of the charge recombination occurring at the substrate/electrolyte interface represents the main reason for the improvement of the photovoltaic efficiency. - Highlights: • Niobium pentoxide thin films were fabricated through pulsed laser deposition. • The deposited films were employed as recombination blocking layer in DSCs. • The selection of the optimal film thickness led to the enhancement of the efficiency

  1. Enhancement of photoconversion efficiency in dye-sensitized solar cells exploiting pulsed laser deposited niobium pentoxide blocking layers

    Energy Technology Data Exchange (ETDEWEB)

    Sacco, Adriano, E-mail: adriano.sacco@iit.it [Center for Space Human Robotics@PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Di Bella, Maurizio Salvatore [Department of Energy, Information Engineering and Mathematical Models (DEIM), Thin Films Laboratory, Università di Palermo, Viale delle Scienze, Building 9, 90128 Palermo (Italy); Gerosa, Matteo [Center for Space Human Robotics@PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Applied Science and Technology Department (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Chiodoni, Angelica; Bianco, Stefano [Center for Space Human Robotics@PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Mosca, Mauro; Macaluso, Roberto; Calì, Claudio [Department of Energy, Information Engineering and Mathematical Models (DEIM), Thin Films Laboratory, Università di Palermo, Viale delle Scienze, Building 9, 90128 Palermo (Italy); Pirri, Candido Fabrizio [Center for Space Human Robotics@PoliTo, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Applied Science and Technology Department (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2015-01-01

    Among all the photovoltaic technologies developed so far, dye-sensitized solar cells are considered as a promising alternative to the expensive and environmentally unfriendly crystalline silicon-based solar cells. One of the possible strategies employed to increase their photovoltaic efficiency is to reduce the charge recombination at the cell conductive substrate through the use of a compact blocking layer. In this paper, we report on the fabrication and characterization of dye-sensitized solar cells employing niobium pentoxide (Nb{sub 2}O{sub 5}) thin film blocking layer deposited through the pulsed laser deposition technique on conductive substrates. The careful selection of the optimal film thickness led to a 30% enhancement of the photoconversion efficiency with respect to reference cells fabricated without blocking layer. Open circuit voltage decay and electrochemical impedance spectroscopy techniques proved that the effective suppression of the charge recombination occurring at the substrate/electrolyte interface represents the main reason for the improvement of the photovoltaic efficiency. - Highlights: • Niobium pentoxide thin films were fabricated through pulsed laser deposition. • The deposited films were employed as recombination blocking layer in DSCs. • The selection of the optimal film thickness led to the enhancement of the efficiency.

  2. Growth of monolithic full-color GaN-based LED with intermediate carrier blocking layers

    Science.gov (United States)

    El-Ghoroury, Hussein S.; Yeh, Milton; Chen, J. C.; Li, X.; Chuang, Chih-Li

    2016-07-01

    Specially designed intermediate carrier blocking layers (ICBLs) in multi-active regions of III-nitride LEDs were shown to be effective in controlling the carrier injection distribution across the active regions. In principle, the majority of carriers, both holes and electrons, can be guided into targeted quantum wells and recombine to generate light of specific wavelengths at controlled current-densities. Accordingly we proposed and demonstrated a novel monolithic InGaN-based LED to achieve three primary colors of light from one device at selected current densities. This LED structure, which has three different sets of quantum wells separated with ICBLs for three primary red-green-blue (RGB) colors, was grown by metal-organic chemical vapor deposition (MOCVD). Results show that this LED can emit light ranging from 460 to 650 nm to cover the entire visible spectrum. The emission wavelength starts at 650 nm and then decreases to 460 nm or lower as the injection current increases. In addition to three primary colors, many other colors can be obtained by color mixing techniques. To the best of our knowledge, this is the first demonstration of monolithic full-color LED grown by a simple growth technique without using re-growth process.

  3. Electron transport mechanism of bathocuproine exciton blocking layer in organic photovoltaics.

    Science.gov (United States)

    Lee, Jeihyun; Park, Soohyung; Lee, Younjoo; Kim, Hyein; Shin, Dongguen; Jeong, Junkyeong; Jeong, Kwangho; Cho, Sang Wan; Lee, Hyunbok; Yi, Yeonjin

    2016-02-21

    Efficient exciton management is a key issue to improve the power conversion efficiency of organic photovoltaics (OPVs). It is well known that the insertion of an exciton blocking layer (ExBL) having a large band gap promotes the efficient dissociation of photogenerated excitons at the donor-acceptor interface. However, the large band gap induces an energy barrier which disrupts the charge transport. Therefore, building an adequate strategy based on the knowledge of the true charge transport mechanism is necessary. In this study, the true electron transport mechanism of a bathocuproine (BCP) ExBL in OPVs is comprehensively investigated by in situ ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy, density functional theory calculation, and impedance spectroscopy. The chemical interaction between deposited Al and BCP induces new states within the band gap of BCP, so that electrons can transport through these new energy levels. Localized trap states are also formed upon the Al-BCP interaction. The activation energy of these traps is estimated with temperature-dependent conductance measurements to be 0.20 eV. The Al-BCP interaction induces both transport and trap levels in the energy gap of BCP and their interplay results in the electron transport observed.

  4. Electron transport mechanism of bathocuproine exciton blocking layer in organic photovoltaics.

    Science.gov (United States)

    Lee, Jeihyun; Park, Soohyung; Lee, Younjoo; Kim, Hyein; Shin, Dongguen; Jeong, Junkyeong; Jeong, Kwangho; Cho, Sang Wan; Lee, Hyunbok; Yi, Yeonjin

    2016-02-21

    Efficient exciton management is a key issue to improve the power conversion efficiency of organic photovoltaics (OPVs). It is well known that the insertion of an exciton blocking layer (ExBL) having a large band gap promotes the efficient dissociation of photogenerated excitons at the donor-acceptor interface. However, the large band gap induces an energy barrier which disrupts the charge transport. Therefore, building an adequate strategy based on the knowledge of the true charge transport mechanism is necessary. In this study, the true electron transport mechanism of a bathocuproine (BCP) ExBL in OPVs is comprehensively investigated by in situ ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy, density functional theory calculation, and impedance spectroscopy. The chemical interaction between deposited Al and BCP induces new states within the band gap of BCP, so that electrons can transport through these new energy levels. Localized trap states are also formed upon the Al-BCP interaction. The activation energy of these traps is estimated with temperature-dependent conductance measurements to be 0.20 eV. The Al-BCP interaction induces both transport and trap levels in the energy gap of BCP and their interplay results in the electron transport observed. PMID:26821701

  5. Enhancing Carrier Injection Using Graded Superlattice Electron Blocking Layer for UVB Light-Emitting Diodes

    KAUST Repository

    Janjua, Bilal

    2014-12-01

    We have studied enhanced carrier injection by having an electron blocking layer (EBL) based on a graded superlattice (SL) design. Here, we examine, using a selfconsistent 6 × 6 k.p method, the energy band alignment diagrams under equilibrium and forward bias conditions while also considering carrier distribution and recombination rates (Shockley-Read-Hall, Auger, and radiative recombination rates). The graded SL is based on AlxGa1-xN (larger bandgap) Al0:5Ga0:5N (smaller bandgap) SL, where x is changed from 0.8 to 0.56 in steps of 0.06. Graded SL was found to be effective in reducing electron leakage and enhancing hole injection into the active region. Due to our band engineering scheme for EBL, four orders-of-magnitude enhancement were observed in the direct recombination rate, as compared with the conventional bulk EBL consisting of Al0:8Ga0:2N. An increase in the spatial overlap of carrier wavefunction was obtained due to polarization-induced band bending in the active region. An efficient single quantum-well ultraviolet-B light-emitting diode was designed, which emits at 280 nm. This is the effective wavelength for water disinfection application, among others.

  6. Nanoporous TiO{sub 2} aerogel blocking layer with enhanced efficiency for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Zheng-Ying [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Gao, Xiang-Dong, E-mail: xdgao@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Li, Xiao-Min [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Jiang, Zheng-Wu; Huang, Yu-Di [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Tongji University, 48000 Cao’an Road, Shanghai 201804 (China)

    2014-03-25

    Highlights: • TiO{sub 2} aerogel film was used as the blocking layer in the photoanode of DSSC. • The film was deposited via sol–gel and ambient-drying process sintering at 500 °C. • Power conversion efficiency was improved by 36% on P25 based photoanode. • Greatly inhibited recombination and enhanced electron lifetime were observed. • The slow diffusion rate of I{sub 3}{sup -} ions in small pores of aerogel plays a key role. -- Abstract: TiO{sub 2} aerogel film possessing nanoporous feature was used as the blocking layer between fluorine-doped tin oxide (FTO) substrate and mesoporous TiO{sub 2} layer in dye-sensitized solar cell (DSSC). TiO{sub 2} aerogel film was deposited on FTO glass via sol–gel and ambient drying processes and sintered at 500 °C, which exhibited the crystallite size of 5–25 nm, the pore size of 3–10 nm, and the thickness of ∼320 nm. Brunauer–Emmett–Teller (BET) analysis confirmed its nanoporous feature and average pore size of 3.8 nm after annealing at 500 °C. In addition, TiO{sub 2} aerogel film showed good interfacial adhesion with FTO and mesoporous TiO{sub 2} layer, high transmittance over 70% in the visible-near infrared band, and large band gap of 3.67 eV. The DSSC device based on this aerogel blocking layer showed obviously enhanced photocurrent density (J{sub sc}) and open-circuit voltage (V{sub oc}) compared with the cell without blocking layer. The highest conversion efficiency of 6.0% was achieved for P25 TiO{sub 2} mesoporous photoanode based on the aerogel blocking layer, improved by 36% than the control cell. The much decreased recombination frequency (aerogel cell: 11.9 Hz; control cell: 31.5 Hz) observed in Nyquist plots, together with the much prolonged electron lifetime (aerogel cell: ∼1 s; control cell: 0.02–0.1 s at 0.2–0.55 V) obtained from open-circuit voltage decay curves, indicated that the increased electron life and retarded recombination at FTO/electrolyte interface were primarily

  7. Electron-blocking mechanisms at the hole transport layer-emissive layer interface in polymer light-emitting diodes: enhanced device performance with a novel electron-blocking interlayer

    Science.gov (United States)

    Yan, He; Marks, Tobin J.

    2004-11-01

    The interface between the hole transport layer (HTL) and emissive layer (EML) in polymer light-emitting diodes (PLEDs) has attracted intense research attentioin since the initial discovery of PLEDs in 1989. In this contribution, we analyze the electron-blocking properties of various HTL at this interface and their effect on PLED device performance. We find that poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) - a conventional PLED HTL - does not possess optimum electron-blocking properties and that PLED device performance can be significantly enhanced by inserting a new type of electron-blocking layer (EBL) between the PEDOT-PSS HTL and EML. The new EBLs developed in this study consist of two major components: a siloxane-derivatized, crosslinkable, TPD-like triarylamine hole-transporting material, such as 4,4"-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl (TPDSi2), and a hole-transporting polymer, such as poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl) diphenylamine) (TFB). TPDSi2 undergoes crosslinking in air and rendering the TPDSi2 + TFB blend insoluble. With the TPDSi2 + TFB EBL inserted between PEDOT-PSS and BT layers, PLED device current density is reduced, device light output and current efficiency are dramatically increased (maximum current efficiency ~ 17 cd/A). Our result shows: 1) insufficient electron-blocking by PEDOT-PSS is another reason for the poor performance of PEDOT-PSS/BT based devices; 2) PLED device performance can be dramatically enhanced with a triarylamine siloxane-based EBLs.

  8. Performance improvement of InGaN blue light-emitting diodes with several kinds of electron-blocking layers

    Institute of Scientific and Technical Information of China (English)

    Chen Jun; Fan Guang-Han; Zhang Yun-Yan; Pang Wei; Zheng Shu-Wen; Yao Guang-Rui

    2012-01-01

    The performance of lnGaN blue light-emitting diodes(LEDs)with different kinds of electron-blocking layers is investigated numerically.We compare the simulated emission spectra,electron and hole concentrations,euergy band diagrams,electrostatic fields,and internal quantum efficiencies of the LEDs.The LED using A1GaN with gradually increasing Al content from 0% to 20% as the electron-blocking layer(EBL)has a strong spectrum intensity,mitigates efficiency droop,and possesses higher output power compared with the LEDs with the other three types of EBLs.These advantages could be because of the lower electron leakage current and more effective hole injection.The optical performance of the specifically designed LED is also improved in the case of large injection current.

  9. CMOS compatible strategy based on selective atomic layer deposition of a hard mask for transferring block copolymer lithography patterns

    International Nuclear Information System (INIS)

    A generic, CMOS compatible strategy for transferring a block copolymer template to a semiconductor substrate is demonstrated. An aluminum oxide (Al2O3) hard mask is selectively deposited by atomic layer deposition in an organized array of holes obtained in a PS matrix via PS-b-PMMA self-assembly. The Al2O3 nanodots act as a highly resistant mask to plasma etching, and are used to pattern high aspect ratio (>10) silicon nanowires and nanopillars.

  10. Layer-block tectonics of Cenozoic basements and formation of intra-plate basins in Nansha micro-plate,southern South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU Hailing; XIE Guofa; LIN Qiujin; ZHENG Hongbo; LIU Yingchun

    2009-01-01

    Layer-block tectonics (LBT) concept, with the core of pluralistic geodynamic outlook and multi-layer-sliding tectonic outlook, is one of new keys to study 3-dimensional solid and its 4-dimensional evolution history of global tectonic system controlled by global geodynamics system. The LBT concept is applied to study the lithospheric tectonics of the southern South China Sea (SCS). Based on the analysis of about 30 000 km of geophysical and geological data, some layer-blocks in the Nansha micro-plate can be divided as Nansha ultra-crustal layer-block, Zengmu crustal layer-block, Nanwei (Rifleman bank)-Andu (Ardasier bank) and Liyue (Reed bank)-North Palawan crustal layer-blocks, Andu-Bisheng and Liyue-Banyue basemental layer-blocks. The basic characteristics of the basemental layer-blocks have been dicussed, and three intra-plate basin groups are identified. The intra-plate basins within Nansha micro-plate can be divided into three basin groups of Nanwei-Andu, Feixin-Nanhua, and Liyue-North Palawan based on the different geodynamics. In the light of pluralistic geodynamic concept, the upheaving force induced by the mid-crust plastic layer is proposed as the main dynamical force which causes the formation of the intra-plate basins within the Nansha micro-plate. Finally, models of a face-to-face dip-slip-detachment of basemental layer-block and a unilateral dip-slip-detachment of basemental layer-block are put forward for the forming mechanisms of the Nanwei-Andu and Liyue-North Palawan intra-plate basin groups, respectively.

  11. Effect of perylenetetracarboxylic dianhydride layer as a hole blocking layer on photovoltaic performance of poly-vinylcarbazole: C{sub 60} bulk heterojunction thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Nomura, Katsunori; Suzuki, Atsushi; Kikuchi, Kenji

    2012-01-31

    Thin film solar cells with a structure of poly(9-vinylcarbazole) and C{sub 60} bulk heterojunction were fabricated and characterized. The effects of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) as a hole blocking layer for the organic solar cells between active layer and metal layer were also investigated, and the optimized cell structures with PTCDA improved the short-circuit current density and fill factor up to twice values, which resulted in an increase of the conversion efficiency. Microstructure analysis was carried out by using X-ray diffraction and transmission electron microscopy, which indicated the bulk nanocomposite structure Energy levels of the molecules were calculated, and the interfacial structure was discussed based on the experimental and calculated results.

  12. An air-stable inverted photovoltaic device using ZnO as the electron selective layer and MoO3 as the blocking layer

    Institute of Scientific and Technical Information of China (English)

    SONG Peng-fei; QIN Wen-jing; DING Guo-jing; YAN Qi-qi; YANG Li-ying; YIN Shou-gen

    2011-01-01

    An air-stable photovoltaic device based on znic oxide nanoparticles(ZNP) in an inverted structure of indium tin oxide (ITO)/ZnO/poly(3-hexylthiophene)(P3HT):[6,6]-phenyl C61-butyric acid methyl ester(PCBM)/MoO3/Ag is studied.We find that the optimum thickness of the MoO3 layer is 2 nm.When the MoO3 blocking layer is introduced,the fill factor of the devices is increased from 29% to 40%,the power conversion efficiency is directly promoted from 0.35% to 1.27%.The stability under ambient conditions of this inverted structure device much is better due to the improved stability at the polymer/Ag interface.The enhancement is attributed to the high carriers mobility and suitable band gap of MoO3 layer.

  13. Enhancing Color Purity and Stable Efficiency of White Organic Light Diodes by Using Hole-Blocking Layer

    Directory of Open Access Journals (Sweden)

    Chien-Jung Huang

    2014-01-01

    Full Text Available The organic light-emitting diodes with triple hole-blocking layer (THBL formation sandwich structure which generate white emission were fabricated. The 5,6,11,12-tetraphenylnapthacene (Rubrene, (4,4′-N,N′-dicarbazolebiphenyl (CBP, and 4,4′-bis(2,2′diphenylvinil-1,1′-biphenyl (DPVBi were used as emitting materials in the device. The function of CBP layer is not only an emitting layer but also a hole-blocking layer (HBL, and the Rubrene was doped into the CBP. The optimal configuration structure was indium tin oxide (ITO/Molybdenum trioxide (MoO3 (5 nm/[4,4-bis[N-(1-naphthyl-N-phenylamino]biphenyl (NPB (35 nm/CBP (HBL1 (5 nm/DPVBi (I (10 nm/CBP (HBL2 : Rubrene (4 : 1 (3 nm/DPVBi (II (30 nm/CBP (HBL3 (2 nm/4,7-diphenyl-1,10-phenanthroline (BPhen (10 nm/Lithium fluoride (LiF/aluminum (Al. The result showed that the device with Rubrene doped in CBP (HBL2 exhibited a stable white emission with the color coordinates of (0.322, 0.368, and the coordinate with the slight shift of ±Δx,y = (0.001, 0.011 for applied voltage of 8–12 V was observed.

  14. Influences of alcoholic solvents on spray pyrolysis deposition of TiO2 blocking layer films for solid-state dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Influences of alcoholic solvents for titanium diisopropoxide bis(acetylacetonate) (TPA) precursor solutions on the spray pyrolysis deposited TiO2 films and the photovoltaic performance of the solid-state dye-sensitized solar cells (SDSCs) using these TiO2 films as the blocking layers were investigated. Smooth TiO2 films were obtained by spray pyrolysis deposition of a TPA solution in isopropanol (IPA) at a relatively low temperature of 260 °C. On the other hand, when ethanol was used as solvent, the TiO2 films fabricated at the same temperature showed much rougher surfaces with many pinholes. Our results showed that ethanol reacts with TPA to form titanium diethoxide bis(acetylacetonate) (TEA), which requires a higher thermal decomposition temperature than that of TPA. SDSCs with TiO2 blocking layer films fabricated using a TPA solution in IPA showed higher power conversion efficiencies with smaller variations. - Graphical abstract: Alcoholic solvents used for the TiO2 precursor play a critical role in determining the surface morphology of blocking layers and thus the photovoltaic performance of the SDSCs. Highlights: ► Solvent influences morphology of spray pyrolysis deposited TiO2 blocking layer. ► Ethanol reacts with TPA, resulting poor quality of blocking layer. ► Isopropanol is better than ethanol for obtaining smooth blocking layer. ► SDSC with blocking layer made with isopropanol showed better performance.

  15. Development of dual-layer GSO depth-of-interaction block detector using angled optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, Satoshi, E-mail: okumura.satoshi@c.mbox.nagoya-u.ac.jp [Nagoya University Graduate School of Medicine (Japan); Yamamoto, Seiichi [Nagoya University Graduate School of Medicine (Japan); Watabe, Hiroshi [Cyclotron and Radioisotope Center (CYRIC), Tohoku University (Japan); Kato, Natsuki; Hamamura, Huka [Nagoya University Graduate School of Medicine (Japan)

    2015-05-01

    A PET system for small animals requires a small detector ring to obtain high-spatial resolution images. However, when we use a relatively large size of photodetector such as a position-sensitive photomultiplier tube (PSPMT), the detector ring is arranged in a hexagonal- or octagonal-shape, and the PET system has large gaps between the block detectors. The large gaps produce image distortion, and the reconstruction algorithm is difficult. To solve these problems, we proposed to arrange two scintillator blocks on one PSPMT using two angled optical fiber-based image guides. We could set two scintillator blocks angled at 22.5° on a PSPMT so that these scintillator blocks are arranged in a nearly circular (hexadecagonal) shape with eight developed block detectors. We used Gd{sub 2}SiO{sub 5} (GSO) scintillators with Ce concentrations of 1.5 mol% (decay time: 39 ns) and 0.4 mol% (decay time: 63 ns). Sizes of these GSO cells were 1.6×2.4×7.0 mm{sup 3} and 1.6×2.4×8.0 mm{sup 3} for 1.5 mol% Ce and 0.4 mol% Ce, respectively. These two types of GSO were arranged in an 11×15 matrix and optically coupled in the depth direction to form a depth-of-interaction (DOI) detector. Two GSO blocks and two optical fiber-based image guides were optically coupled to a 2-in. PSPMT (Hamamatsu Photonics H8500: 8×8 anodes). We measured the performances of the block detector with Cs-137 gamma photons (662-keV). We could resolve almost all pixels clearly in a two-dimensional position histogram. The average peak-to-valley ratios (P/Vs) of the two-dimensional position histogram along profiles were 2.6 and 4.8 in horizontal and vertical directions, respectively. The energy resolution was 28.4% full-width at half-maximum (FWHM). The pulse shape spectra showed good separation with a P/V of 5.2. The developed block detector performed well and shows promise for the development of high-sensitivity and high-spatial resolution PET systems.

  16. Development of dual-layer GSO depth-of-interaction block detector using angled optical fiber

    International Nuclear Information System (INIS)

    A PET system for small animals requires a small detector ring to obtain high-spatial resolution images. However, when we use a relatively large size of photodetector such as a position-sensitive photomultiplier tube (PSPMT), the detector ring is arranged in a hexagonal- or octagonal-shape, and the PET system has large gaps between the block detectors. The large gaps produce image distortion, and the reconstruction algorithm is difficult. To solve these problems, we proposed to arrange two scintillator blocks on one PSPMT using two angled optical fiber-based image guides. We could set two scintillator blocks angled at 22.5° on a PSPMT so that these scintillator blocks are arranged in a nearly circular (hexadecagonal) shape with eight developed block detectors. We used Gd2SiO5 (GSO) scintillators with Ce concentrations of 1.5 mol% (decay time: 39 ns) and 0.4 mol% (decay time: 63 ns). Sizes of these GSO cells were 1.6×2.4×7.0 mm3 and 1.6×2.4×8.0 mm3 for 1.5 mol% Ce and 0.4 mol% Ce, respectively. These two types of GSO were arranged in an 11×15 matrix and optically coupled in the depth direction to form a depth-of-interaction (DOI) detector. Two GSO blocks and two optical fiber-based image guides were optically coupled to a 2-in. PSPMT (Hamamatsu Photonics H8500: 8×8 anodes). We measured the performances of the block detector with Cs-137 gamma photons (662-keV). We could resolve almost all pixels clearly in a two-dimensional position histogram. The average peak-to-valley ratios (P/Vs) of the two-dimensional position histogram along profiles were 2.6 and 4.8 in horizontal and vertical directions, respectively. The energy resolution was 28.4% full-width at half-maximum (FWHM). The pulse shape spectra showed good separation with a P/V of 5.2. The developed block detector performed well and shows promise for the development of high-sensitivity and high-spatial resolution PET systems

  17. CAD中图层图块在机械图样中的应用%The Application of Layers and Blocks in Mechanical Drawings by the CAD

    Institute of Scientific and Technical Information of China (English)

    徐亚娥

    2012-01-01

    以法兰盘零件图为例,描述了图层、图块的功能,同时描述了图层设置方法,图块设置方法.探讨了绘制零件图时图层、图块应用方法与技巧.%Describes function of layers and blocks by the flange parts diagram and describes setting method of layers and blocks. Explores the application methods and techniques of layers and blocks when the part is drawn diagram.

  18. Generation of Nonlinear Force Driven Blocks from Skin Layer Interaction of Petawatt-Picosecond Laser Pulses for ICF

    Institute of Scientific and Technical Information of China (English)

    Heinrich Hora; K. Jungwirth; B. Kralikova; J. Kraska; L. Laska; Liu Hong; G.H. Miley; P. Parys; Peng Hansheng; M. Pfeifer; K. Rohlena; Cang Yu; J. Skala; Z. Skladanowski; L. Torrisi; J. Ullschmied; J. Wolowski; Zhang Weiyan; He Xiantu; Zhang Jie; F. Osman; J. Badziak; F.P. Boody; S. Gammino; R. H(o)pfl

    2004-01-01

    The discovery of the essential difference of maximum ion energy for TW-ps laser plasma interaction compared with the 100 ns laser pulses [1] led to the theory of a skin layer model [2] where the control of prepulses suppressed the usual relativistic self-focusing. The subsequent generation of two nonlinear force driven blocks has been demonstrated experimentally and in extensive numerical studies where one block moves against the laser light and the other block into the irradiated target. These blocks of nearly solid state density DT plasma correspond to ion beam current densities [3] exceeding 1010 A/cm2 where the ion velocity can be chosen up to highly relativistic values. Using the results of the expected ignition of DT fuel by light ion beams, a selfsustained fusion reaction front may be generated even into uncompressed solid DT fuel similar to the Nuckolls-Wood [4] scheme where 10 kJ laser pulses produce 100 MJ fusion energy. This new and simplified scheme of laser-ICF needs and optimisation of the involved parameters.

  19. Large Stokes shift downshifting Eu(III) films as efficiency enhancing UV blocking layers for dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, M.; Ahmed, H.; Doran, J.; Norton, B. [Dublin Energy Laboratory, Dublin Institute of Technology (Ireland); Bosch-Jimenez, P.; Della Pirriera, M.; Torralba-Calleja, E.; Gutierrez Tauste, D.; Aubouy, L. [Leitat Technological Center, Terrassa (Spain); Daren, S.; Solomon-Tsvetkov, F. [Daren Laboratories, Ness-Ziona (Israel); Galindo, S.; Voz, C.; Puigdollers, J. [Universitat Politecnica Catalunya, Barcelona (Spain)

    2015-01-01

    Large Stokes shift downshifting organolanthanide complex, Eu(tta){sub 3}phen, is examined for inclusion in polymeric layers to replace the UV blocking layer in dye sensitized solar cell (DSSC) technology. The UV blocking layer increases stability but power conversion efficiency decreases as incident UV photons are not converted into photocurrent. Eu(tta){sub 3}phen doped polymeric film are prepared and attached to DSSC devices following optimized thickness and concentration from a ray-trace numerical model for the specific DSSC. External quantum efficiency is significantly increased in the UV spectral region compared to DSSCs utilizing a passive, non-luminescent, UV-BL. High Eu(tta){sub 3}phen film transparency in the visible range minimizes DSSC EQE losses at visible wavelengths. Short-circuit current (I{sub sc}) enhancement due to downshifting is demonstrated (∝1%) in small-scale DSSC prototypes, where the specific geometry limits the photon collection efficiency and overall enhancement. Model predictions indicate that 2%-3% Isc enhancement is realizable in flexible single DSSC compared to, non-luminescent, UV-BL. Added to this, in outdoor conditions taking into account diffuse light, the increment in I{sub sc} can increase 50% more. Although photostability of the blended LSS-DS polymer films is not sufficient to be useful for medium-long term outdoor PV applications, the results demonstrate that significant efficiency enhancement can be realized. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Increased luminance of MEH-PPV and PFO based PLEDs by using salmon DNA as an electron blocking layer

    International Nuclear Information System (INIS)

    The effect of salmon DNA-CTMA as an electron blocking layer (EBL) has been examined on the performance of MEH-PPV and PFO-based light emitting diodes. Though the turn-on voltage increases with incorporation of EBL, a significant increase in luminance and luminous efficiency for both the devices is observed. The EBL improves the device performance by blocking electrons at the EBL-polymer interface, thereby increasing the recombination probability of electrons and holes. The luminance of the MEH-PPV based Bio-LED increases to 100 cd/m2 from 30 cd/m2 while a corresponding increase for the PFO based LED is to 160 cd/m2 from 80 cd/m2 with and without EBL, respectively.

  1. Development of ultra pure germanium epi layers for blocked impurity band far infrared detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M.P.

    1991-05-01

    The main goals of this paper are: (1) To develop a low-pressure CVD (LPCVD) process that allows epitaxial growth at lower temperatures. Lower temperatures will allow the achievement of a sharp dopant profile at the substrate/epi-layer interface. Less out-diffusion from the substrate would allow the use of thinner epitaxial layers, which would lead to a larger depletion width in the photoactive region. LPCVD also avoids, to a great extent, gas-phase nucleation, which would cause Ge particulates to fall onto the wafer surface during growth. (2) To reduce high levels of oxygen and copper present at the wafer interface, as observed by secondary ion mass spectroscopy (SIMS). In order to achieve high-quality epitaxial layers, it is imperative that the substrate surface be of excellent quality. (3) To make and test detectors, after satisfactory epitaxial layers have been made.

  2. Cement stabilized red earth as building block and structural pavement layer

    Directory of Open Access Journals (Sweden)

    G.V. RAMA SUBBARAO

    2014-12-01

    Full Text Available Red Earth is most commonly used as material in the building and road construction. Many a times, the red earth found in various quarries is found not suitable for construction. Cement of 4 and 8% of dry mass of red earth was added to improve its suitability as building block and structural pavement material. To know the influence of waste plastic fiber on cement stabilized red earth, 1% fiber was also added to the mixture. It is shown that the compressive strength of cement stabilized red earth blocks was improved with seven days of curing. The addition of cement to red earth enhanced soaked CBR value. The soaked CBR value of fiber reinforced cement stabilized red earth was about 1.3 to 1.5 times that of unreinforced cement stabilized red earth.

  3. CMOS compatible strategy based on selective atomic layer deposition of a hard mask for transferring block copolymer lithography patterns

    Energy Technology Data Exchange (ETDEWEB)

    Gay, G; Grampeix, H; Martin, F; Jalaguier, E; De Salvo, B [CEA LETI MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Baron, T; Agraffeil, C; Salhi, B; Chevolleau, T; Cunge, G; Tortai, J-H, E-mail: guillaume.gay@cea.fr, E-mail: thierry.baron@cea.fr [CNRS-LTM, 17 rue des Martyrs, 38054 Grenoble (France)

    2010-10-29

    A generic, CMOS compatible strategy for transferring a block copolymer template to a semiconductor substrate is demonstrated. An aluminum oxide (Al{sub 2}O{sub 3}) hard mask is selectively deposited by atomic layer deposition in an organized array of holes obtained in a PS matrix via PS-b-PMMA self-assembly. The Al{sub 2}O{sub 3} nanodots act as a highly resistant mask to plasma etching, and are used to pattern high aspect ratio (>10) silicon nanowires and nanopillars.

  4. Polarization-matched quaternary superlattice electron blocking layer in blue InGaN light-emitting diodes

    Science.gov (United States)

    Kuo, Yen-Kuang; Chen, Fang-Ming; Chang, Jih-Yuan; Lin, Bing-Cheng

    2016-05-01

    The effect of polarization-matched AlInGaN/AlGaN superlattice (SL) electron blocking layer (EBL) on the physical characteristics of blue InGaN light-emitting diodes (LEDs) is investigated numerically. Simulation results show that the optical performance of the LEDs with polarization-matched SL EBL can be markedly improved due to the effectively suppressed polarization effect, enhanced hole injection efficiency, and reduced electron overflow. Comparing to the LEDs with conventional AlGaN EBL, an improvement of 53% in light output power is achieved for the proposed LED structure.

  5. Enhance Carrier Density Distributions between Double Quantum Wells Violet Ingan Laser Diode by Using Alingan as a Blocking Layer

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Rafid A; Ibrahim, Kamarulazizi, E-mail: rafid_alabdali@yahoo.com, E-mail: kamarul@usm.my [Nano-Optoelectronics Research and Technology Laboratory (N.O.R), School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2011-02-15

    Enhancement of carrier (electron and hole) density distributions between double quantum wells (QWs) violet InGaN laser diode (LD) has numerically been obtained by using quaternary AlInGaN as a blocking layer (BL) instead of conventional ternary AlGaN BL. Simulation results indicate that the quaternary BL has a higher refractive index and optical intensity inside the active region than the ternary BL which leads to reducing the threshold current of the LD from 16.42 mA with ternary BL to 13.67 mA with quaternary BL.

  6. Tailoring of polarization in electron blocking layer for electron confinement and hole injection in ultraviolet light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yu-Hsuan; Pilkuhn, Manfred H. [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Fu, Yi-Keng; Chu, Mu-Tao [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan (China); Huang, Shyh-Jer, E-mail: yksu@mail.ncku.edu.tw, E-mail: totaljer48@gmail.com [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California 90095 (United States); Su, Yan-Kuin, E-mail: yksu@mail.ncku.edu.tw, E-mail: totaljer48@gmail.com [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Electronic Engineering, Kun-Shan University, Tainan 71003, Taiwan (China); Wang, Kang L. [Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California 90095 (United States)

    2014-03-21

    The influence of the AlGaN electron blocking layer (EBL) with graded aluminum composition on electron confinement and hole injection in AlGaN-based ultraviolet light-emitting diodes (LEDs) are investigated. The light output power of LED with graded AlGaN EBL was markedly improved, comparing to LED with conventional EBL. In experimental results, a high increment of 86.7% can be obtained in light output power. Simulation analysis shows that via proper modification of the barrier profile from the last barrier of the active region to EBL, not only the elimination of electron overflow to p-type layer can be achieved but also the hole injection into the active region can be enhanced, compared to a conventional LED structure. The dominant factor to the performance improvement is shown to be the modulation of polarization field by the graded Al composition in EBL.

  7. Tailoring of polarization in electron blocking layer for electron confinement and hole injection in ultraviolet light-emitting diodes

    International Nuclear Information System (INIS)

    The influence of the AlGaN electron blocking layer (EBL) with graded aluminum composition on electron confinement and hole injection in AlGaN-based ultraviolet light-emitting diodes (LEDs) are investigated. The light output power of LED with graded AlGaN EBL was markedly improved, comparing to LED with conventional EBL. In experimental results, a high increment of 86.7% can be obtained in light output power. Simulation analysis shows that via proper modification of the barrier profile from the last barrier of the active region to EBL, not only the elimination of electron overflow to p-type layer can be achieved but also the hole injection into the active region can be enhanced, compared to a conventional LED structure. The dominant factor to the performance improvement is shown to be the modulation of polarization field by the graded Al composition in EBL

  8. Cement stabilized red earth as building block and structural pavement layer

    OpenAIRE

    Rama Subbarao, G. V.; J. PURNA CHANDRA RAO

    2014-01-01

    Red Earth is most commonly used as material in the building and road construction. Many a times, the red earth found in various quarries is found not suitable for construction. Cement of 4 and 8% of dry mass of red earth was added to improve its suitability as building block and structural pavement material. To know the influence of waste plastic fiber on cement stabilized red earth, 1% fiber was also added to the mixture. It is shown that the compressive strength of cement stabilized red ear...

  9. High holding voltage segmentation stacking silicon-controlled-rectifier structure with field implant as body ties blocking layer

    Science.gov (United States)

    Yen, Shiang-Shiou; Cheng, Chun-Hu; Lan, Yu-Pin; Chiu, Yu-Chien; Fan, Chia-Chi; Hsu, Hsiao-Hsuan; Chang, Shao-Chin; Jiang, Zhe-Wei; Hung, Li-Yue; Tsai, Chi-Chung; Chang, Chun-Yen

    2016-04-01

    High electrostatic discharge (ESD) protection robustness and good transient-induced latchup immunity are two important issues for high voltage integrate circuit application. In this study, we report a high-voltage-n-type-field (HVNF) implantation to act as the body ties blocking layer in segmented topology silicon-controlled-rectifier (SCR) structure in 0.11 µm 32 V high voltage process. This body ties blocking layer eliminate the elevated triggered voltage in segmented technique. Using a large resistance as shunt resistor in resistor assisted triggered SCRs stacking structure, the double snapback phenomenon is eliminate. The series SCR could be decoupled a sufficient voltage drop to turned-on when a very low current flow through the shunt resistor. The holding voltage and the failure current of 22 V and 3.4 A are achieved in the best condition of segmented topology SCR stacking structure, respectively. It improves the latchup immunity at high voltage ICs application. On the other hand, the triggered voltage almost keep the same value which is identical to SCR single cell without using segmented topology.

  10. Poly(cyclohexylethylene)-block-Poly(lactide) Oligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition.

    Science.gov (United States)

    Yao, Li; Oquendo, Luis E; Schulze, Morgan W; Lewis, Ronald M; Gladfelter, Wayne L; Hillmyer, Marc A

    2016-03-23

    Poly(cyclohexylethylene)-block-poly(lactide) (PCHE-PLA) block polymers were synthesized through a combination of anionic polymerization, heterogeneous catalytic hydrogenation and controlled ring-opening polymerization. Ordered thin films of PCHE-PLA with ultrasmall hexagonally packed cylinders oriented perpendicularly to the substrate surface were prepared by spin-coating and subsequent solvent vapor annealing for use in two distinct templating strategies. In one approach, selective hydrolytic degradation of the PLA domains generated nanoporous PCHE templates with an average pore diameter of 5 ± 1 nm corroborated by atomic force microscopy and grazing incidence small-angle X-ray scattering. Alternatively, sequential infiltration synthesis (SIS) was employed to deposit Al2O3 selectively into the PLA domains of PCHE-PLA thin films. A combination of argon ion milling and O2 reactive ion etching (RIE) enabled the replication of the Al2O3 nanoarray from the PCHE-PLA template on diverse substrates including silicon and gold with feature diameters less than 10 nm.

  11. A tribo-mechanical analysis of PVA-based building-blocks for implementation in a 2-layered skin model.

    Science.gov (United States)

    Morales Hurtado, M; de Vries, E G; Zeng, X; van der Heide, E

    2016-09-01

    Poly(vinyl) alcohol hydrogel (PVA) is a well-known polymer widely used in the medical field due to its biocompatibility properties and easy manufacturing. In this work, the tribo-mechanical properties of PVA-based blocks are studied to evaluate their suitability as a part of a structure simulating the length scale dependence of human skin. Thus, blocks of pure PVA and PVA mixed with Cellulose (PVA-Cel) were synthesised via freezing/thawing cycles and their mechanical properties were determined by Dynamic Mechanical Analysis (DMA) and creep tests. The dynamic tests addressed to elastic moduli between 38 and 50kPa for the PVA and PVA-Cel, respectively. The fitting of the creep compliance tests in the SLS model confirmed the viscoelastic behaviour of the samples with retardation times of 23 and 16 seconds for the PVA and PVA-Cel, respectively. Micro indentation tests were also achieved and the results indicated elastic moduli in the same range of the dynamic tests. Specifically, values between 45-55 and 56-81kPa were obtained for the PVA and PVA-Cel samples, respectively. The tribological results indicated values of 0.55 at low forces for the PVA decreasing to 0.13 at higher forces. The PVA-Cel blocks showed lower friction even at low forces with values between 0.2 and 0.07. The implementation of these building blocks in the design of a 2-layered skin model (2LSM) is also presented in this work. The 2LSM was stamped with four different textures and their surface properties were evaluated. The hydration of the 2LSM was also evaluated with a corneometer and the results indicated a gradient of hydration comparable to the human skin. PMID:27236420

  12. Layer-by-Layer Formation of Block-Copolymer-Derived TiO2 for Solid-State Dye-Sensitized Solar Cells

    KAUST Repository

    Guldin, Stefan

    2011-12-15

    Morphology control on the 10 nm length scale in mesoporous TiO 2 films is crucial for the manufacture of high-performance dye-sensitized solar cells. While the combination of block-copolymer self-assembly with sol-gel chemistry yields good results for very thin films, the shrinkage during the film manufacture typically prevents the build-up of sufficiently thick layers to enable optimum solar cell operation. Here, a study on the temporal evolution of block-copolymer-directed mesoporous TiO 2 films during annealing and calcination is presented. The in-situ investigation of the shrinkage process enables the establishment of a simple and fast protocol for the fabrication of thicker films. When used as photoanodes in solid-state dye-sensitized solar cells, the mesoporous networks exhibit significantly enhanced transport and collection rates compared to the state-of-the-art nanoparticle-based devices. As a consequence of the increased film thickness, power conversion efficiencies above 4% are reached. Fabrication of sufficiently thick mesoporous TiO 2 photoelectrodes with morphology control on the 10 nm length scale is essential for solid-state dye-sensitized solar cells (ss-DSC). This study of the temporal evolution of block-copolymer-directed mesoporous TiO 2 films during annealing and calcination enables the build-up of sufficiently thick films for high-performance ssDSC devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Highly ordered freestanding titanium oxide nanotube arrays using Si-containing block copolymer lithography and atomic layer deposition

    International Nuclear Information System (INIS)

    Highly ordered freestanding TiO2 nanotube arrays with atomic layer control of wall thickness were fabricated using an organic–inorganic hybrid nanoporous template and atomic layer deposition (ALD). The hybrid nanoporous template with a high-aspect-ratio cylindrical nanopore array can be readily fabricated by pattern transfer from a thin silicon-containing block copolymer film into a thick cross-linked organic polymer layer. The template exhibited excellent thermal stability and thus allowed the high-temperature ALD process to conformally deposit TiO2 thin films on the inner surface of cylindrical nanopores. The ultrafine thickness tunability of the ALD process made it possible to develop TiO2 nanotubes with various wall thicknesses. After the template was removed using a dry etch followed by calcination, vertically aligned and highly crystalline anatase TiO2 nanotube arrays were produced without collapse or bundling. We also fabricated the highly uniform freestanding arrays of multi-component nanotubes composed of TiO2/Al2O3/TiO2 nanolaminate and Ti–Al–O mixed-phase films with precisely controlled thickness and composition. (paper)

  14. ReO{sub x} charge injection/blocking layers in organic electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Luo Jiaxiu; Xiao Lixin; Chen Zhijian; Qu Bo; Gong Qihuang, E-mail: xiao66@pku.edu.c, E-mail: qhgong@pku.edu.c [State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China)

    2010-09-29

    The charge transport of rhenium oxide (ReO{sub x}) in organic electronic devices was investigated. The hole injection/transport was blocked and the electron injection/transport was enhanced with doping of ReO{sub x} in organic electronic devices. Thus the charge balance and efficiency of organic light-emitting diodes were improved; current efficiency of 2.7 cd A{sup -1} at 20 mA cm{sup -2} for the device with ReO{sub x} was higher than 1.5 cd A{sup -1} for the device without it. In the case of organic photovoltaic cells, the open-circuit voltage (V{sub oc}), 0.58 V, was higher compared with the device without ReO{sub x} (0.44 V) due to the improvement of interface properties. The power conversion efficiency was increased to 2.27% by the combination of ReO{sub x} (increases V{sub oc}) with poly(3,4-ethylenedioxythiophene) : poly(styrene-sulfonate) (improves hole transport to increase J{sub sc}) on the modification of the anode, higher than 1.85% for the device without ReO{sub x}.

  15. Weak-link behaviour observed in iron-based superconductors with thick perovskite-type blocking layers

    International Nuclear Information System (INIS)

    The synthesis of iron-based superconductors with thick perovskite-type blocking layers, (Fe2As2)(Ca4(Mg0.25,Ti0.75)3O8) (22438) and (Fe2As2)(Ca5(Sc0.5Ti0.5)4O11) (225411), has been carried out and their transport properties discussed in comparison with those of fluorine-doped SmFeAsO0.8F0.2 (Sm1111) superconductors. Microstructural observation revealed that superconducting grains have a platelet shape and are strongly coupled with each other, particularly in 22438. The onset transition temperature (Tc) of 22438 reached up to 47.5 K and its very high upper critical field at low temperatures was suggested by a steep slope (dHc2/dT) near Tc as large as −19.8 T K−1. The resistance curves under various magnetic fields showed a basically two-step-like character of the superconducting transitions, where the effect of magnetic field is weaker at the onset part near the normal state in comparison to the tail part. The broadening of the tail part suggests a weak-link connection between superconducting grains. Two distinct scales of current flow corresponding to inter- and intragranular currents were confirmed by the remanent magnetization measurement of bulk samples, and their calculated intergranular current densities are relatively low. The analysis of their superconducting properties suggests evidence of the weak-link intergrain nature and high electromagnetic anisotropy of these iron-based superconductors with thick oxide blocking layers. (paper)

  16. Directing Hybrid Structures by Combining Self-Assembly of Functional Block Copolymers and Atomic Layer Deposition: A Demonstration on Hybrid Photovoltaics.

    Science.gov (United States)

    Moshonov, Moshe; Frey, Gitti L

    2015-11-24

    The simplicity and versatility of block copolymer self-assembly offers their use as templates for nano- and meso-structured materials. However, in most cases, the material processing requires multiple steps, and the block copolymer is a sacrificial building block. Here, we combine a self-assembled block copolymer template and atomic layer deposition (ALD) of a metal oxide to generate functional hybrid films in a simple process with no etching or burning steps. This approach is demonstrated by using the crystallization-induced self-assembly of a rod-coil block copolymer, P3HT-b-PEO, and the ALD of ZnO. The block copolymer self-assembles into fibrils, ∼ 20 nm in diameter and microns long, with crystalline P3HT cores and amorphous PEO corona. The affinity of the ALD precursors to the PEO corona directs the exclusive deposition of crystalline ZnO within the PEO domains. The obtained hybrid structure possesses the properties desired for photovoltaic films: donor-acceptor continuous nanoscale interpenetrated networks. Therefore, we integrated the films into single-layer hybrid photovoltaics devices, thus demonstrating that combining self-assembly of functional block copolymers and ALD is a simple approach to direct desired complex hybrid morphologies.

  17. Enhancing carrier injection in the active region of a 280nm emission wavelength LED using graded hole and electron blocking layers

    KAUST Repository

    Janjua, Bilal

    2014-02-27

    A theoretical investigation of AlGaN UV-LED with band engineering of hole and electron blocking layers (HBL and EBL, respectively) was conducted with an aim to improve injection efficiency and reduce efficiency droop in the UV LEDs. The analysis is based on energy band diagrams, carrier distribution and recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates) in the quantum well, under equilibrium and forward bias conditions. Electron blocking layer is based on AlaGa1-aN / Al b → cGa1-b → 1-cN / AldGa 1-dN, where a < d < b < c. A graded layer sandwiched between large bandgap AlGaN materials was found to be effective in simultaneously blocking electrons and providing polarization field enhanced carrier injection. The graded interlayer reduces polarization induced band bending and mitigates the related drawback of impediment of holes injection. Similarly on the n-side, the Alx → yGa1-x → 1-yN / AlzGa 1-zN (x < z < y) barrier acts as a hole blocking layer. The reduced carrier leakage and enhanced carrier density in the active region results in significant improvement in radiative recombination rate compared to a structure with the conventional rectangular EBL layers. The improvement in device performance comes from meticulously designing the hole and electron blocking layers to increase carrier injection efficiency. The quantum well based UV-LED was designed to emit at 280nm, which is an effective wavelength for water disinfection application.

  18. Highly reliable top-gated thin-film transistor memory with semiconducting, tunneling, charge-trapping, and blocking layers all of flexible polymers.

    Science.gov (United States)

    Wang, Wei; Hwang, Sun Kak; Kim, Kang Lib; Lee, Ju Han; Cho, Suk Man; Park, Cheolmin

    2015-05-27

    The core components of a floating-gate organic thin-film transistor nonvolatile memory (OTFT-NVM) include the semiconducting channel layer, tunneling layer, floating-gate layer, and blocking layer, besides three terminal electrodes. In this study, we demonstrated OTFT-NVMs with all four constituent layers made of polymers based on consecutive spin-coating. Ambipolar charges injected and trapped in a polymer electret charge-controlling layer upon gate program and erase field successfully allowed for reliable bistable channel current levels at zero gate voltage. We have observed that the memory performance, in particular the reliability of a device, significantly depends upon the thickness of both blocking and tunneling layers, and with an optimized layer thickness and materials selection, our device exhibits a memory window of 15.4 V, on/off current ratio of 2 × 10(4), read and write endurance cycles over 100, and time-dependent data retention of 10(8) s, even when fabricated on a mechanically flexible plastic substrate.

  19. Thermoelectric properties of FeAs based superconductors, with thick perovskite- and Sm-O fluorite-type blocking layers

    Science.gov (United States)

    Singh, S. J.; Shimoyama, J.; Ogino, H.; Kishio, K.

    2015-11-01

    The transport properties (electrical resistivity, Hall and Seebeck coefficient, and thermal conductivity) of iron based superconductors with thick perovskite-type oxide blocking layers and fluorine-doped SmFeAsO were studied to explore their possible potential for thermoelectric applications. The thermal conductivity of former compounds depicts the dominated role of phonon and its value decreases rapidly below the Tc, suggesting the addition of scattering of phonons. Both the Seebeck coefficient (S) and Hall coefficient (RH) of all samples were negative in the whole temperature region below 300 K, indicating that the major contribution to the normal state conductivity is by electrons. In addition, the profile of S(T) and RH(T) of all samples have similar behaviours as would be expected for a multi-band superconductors. Although the estimated thermoelectric figure of merit (ZT) of these compounds was much lower than that of practically applicable thermoelectric materials, however its improvement can be expected by optimizing microstructure of the polycrystalline materials, such as densification and grain orientation.

  20. Enhanced luminous efficiency and brightness using DNA electron blocking layers in bio-organic light emitting diodes

    Science.gov (United States)

    Hagen, Joshua A.

    The biopolymer deoxyribonucleic acid (DNA) has been extracted from salmon (saDNA) and used successfully as an electron blocking layer (EBL) in multiple structures of Organic Light Emitting Diodes (OLED). Water soluble saDNA was complexed with a cationic surfactant hexadecytrimethylammonium chloride (CTMA) which makes the resulting DNA-CTMA molecule water insoluble, and soluble in common organic media such as alcohols. Solutions of DNA-CTMA and butanol make uniform thin films from 20nm to 5 microns in thickness by varying spin coating parameters and molecular weight. The optical properties of DNA-CTMA thin films include high transparency and low optical loss for applications at wavelengths above 400nm. The DNA-CTMA films have an electrical resistivity on the order of 107 O*cm. All of these properties combined made DNA-CTMA a candidate as an EBL in OLEDs, and this resulting device was termed a Bio-organic Light Emitting Diode (BioLED). Enhanced electroluminescent efficiency has been demonstrated in both green and blue emitting BioLEDs. The resulting green and blue BioLEDs showed a maximum luminous efficiency of 8.2 and 0.8 cd/A, respectively. The DNA based BioLEDs were as much as 10x more efficient and 30x brighter than their OLED counterparts. The enhancement in performance is due to the electron blocking action with the 0.9 eV (lowest unoccupied molecular orbital) value, allows hole injection to proceed with a 5.6eV (highest occupied molecular orbital) value. DNA-CTMA has also been successfully deposited in thin film form via molecular beam deposition (MBD). The growth was achieved at 160°C at vacuum levels of 10-5 Torr at a deposition rate of 0.8A/s. MBD grown DNA-CTMA thin films were highly uniform, optically transparent, and adhere to silicon, quartz and glass substrates more strongly than spin coated films. The material deposited was verified as DNA-CTMA through optical absorption, energy dispersive X-ray analysis, and using a DNA indicating fluorescent dye

  1. Low-Threshold-Current and High-out-Power 660 nm Laser Diodes with a p-GaAs Current Blocking Layer for DVD-RAM/R

    Institute of Scientific and Technical Information of China (English)

    ZHENG Kai; MA Xiao-Yu; LIN Tao; WANG Jun; LIU Su-Ping; ZHANG Guang-Ze

    2005-01-01

    @@ We investigate a new structure of high-power 660-nm AlGaInP laser diodes. In the structure, a p-GaAs layer is grown on the ridge waveguide serving as the current-blocking layer, and nonabsorbing windows are only fabricated near the cavity facets to increase the catastrophic-optical-damage level. Stable fundamental mode operation was achieved at up to 80mW without kinks, and the maximum output power was 184mW at 22℃. The threshold current was 40mA.

  2. Seismic motion in urban sites consisting of blocks in welded contact with a soft layer overlying a hard half space: II. large and infinite number of identical equispaced blocks

    CERN Document Server

    Wirgin, A; Groby, Jean-Philippe; Wirgin, Armand

    2006-01-01

    We address the problem of the response to a seismic wave of an urban site consisting of a large and infinite number ($N\\_{b}$) of identical, equispaced blocks overlying a soft layer underlain by a hard substratum. The results of the theoretical analysis, appealing to a space-frequency mode-matching (MM) technique, are compared to those obtained by a space-time finite element (FE) method. The two methods are shown to give rise to much the same prediction of seismic response for $N\\_{b}=10$. The MM technique is also applied to the case $N\\_{b}=\\infty$, notably to reveal the structure and natural frequencies of the vibration modes of the urban site. The mechanism of the interaction between blocks and the ground, as well as that of the collective effects of the blocks, are studied. It is shown that the presence of a large number of blocks modifies the seismic disturbance in a manner which evokes, and may partially account for, what was observed during many earthquakes in Mexico City. Disturbances at a much smalle...

  3. The improvement of GaN-based LED grown on concave nano-pattern sapphire substrate with SiO2 blocking layer

    Science.gov (United States)

    Lin, Jyun-Hao; Huang, Shyh-Jer; Su, Yan-Kuin; Huang, Kai-Wen

    2015-11-01

    In contrast to convex nano-pattern sapphire substrates (NPSS), which are frequently used to fabricate high-quality nitride-based light-emitting diodes (LEDs), concave NPSS have been paid relatively less attention. In this study, a concave NPSS was fabricated, and its nitride epitaxial growth process was evaluated in a step by step manner. A SiO2 layer was used to avoid nucleation over the sidewall and bottom of the nano-patterns to reduce dislocation reformation. Traditional LED structures were grown on the NPSS layer to determine its influence on device performance. X-ray diffraction, etched pit density, inverse leakage current, and internal quantum efficiency (IQE) results showed that dislocations and non-radiative recombination centers are reduced by the NPSS constructed with a SiO2 blocking layer. An IQE twice that on a planar substrate was also achieved; such a high IQE significantly enhanced the external quantum efficiency of the resultant device. Taken together, the results demonstrate that the SiO2 blocking layer proposed in this work can enhance the performance of LEDs.

  4. Cross-Layer Framework for Multiuser Real Time H.264/AVC Video Encoding and Transmission over Block Fading MIMO Channels Using Outage Probability

    Directory of Open Access Journals (Sweden)

    Slavche Pejoski

    2014-01-01

    Full Text Available We present a framework for cross-layer optimized real time multiuser encoding of video using a single layer H.264/AVC and transmission over MIMO wireless channels. In the proposed cross-layer adaptation, the channel of every user is characterized by the probability density function of its channel mutual information and the performance of the H.264/AVC encoder is modeled by a rate distortion model that takes into account the channel errors. These models are used during the resource allocation of the available slots in a TDMA MIMO communication system with capacity achieving channel codes. This framework allows for adaptation to the statistics of the wireless channel and to the available resources in the system and utilization of the multiuser diversity of the transmitted video sequences. We show the effectiveness of the proposed framework for video transmission over Rayleigh MIMO block fading channels, when channel distribution information is available at the transmitter.

  5. Morphology, microstructure, and hardness of titanium (Ti-6Al-4V) blocks deposited by wire-feed additive layer manufacturing (ALM)

    International Nuclear Information System (INIS)

    Highlights: ► The microstructure and hardness of deposited Ti-6Al-4V blocks are investigated. ► Hardness is influenced by post heat treatment rather than by process parameters. ► Microstructure within the prior β-grains varies to some extent from grain to grain. ► A 600 °C/4 h treatment significantly increased the average hardness. - Abstract: Additive layer manufacturing offers a potential for time and cost savings, especially for aerospace components made from costly titanium alloys. In this paper, the morphology, microstructure, chemical composition, and hardness of additive manufactured Ti-6Al-4V blocks are investigated and discussed. Blocks (7 beads wide, 7 layers high) were deposited using Ti-6Al-4V wire and a Nd:YAG laser. Two different sets of parameters are used and three different post heat treatment conditions (as-built, 600 °C/4 h, 1200 °C/2 h) are investigated. The experiments reveal elementary properties of additive manufactured Ti-6Al-4V material in correlation to process parameters and heat treatments, which are discussed comprehensively.

  6. Morphology, microstructure, and hardness of titanium (Ti-6Al-4V) blocks deposited by wire-feed additive layer manufacturing (ALM)

    Energy Technology Data Exchange (ETDEWEB)

    Brandl, Erhard, E-mail: erhard.brandl@eads.net [EADS Innovation Works, Metallic Technologies and Surface Engineering, D-81663 Munich (Germany); Schoberth, Achim, E-mail: achim.schoberth@eads.net [EADS Innovation Works, Metallic Technologies and Surface Engineering, D-81663 Munich (Germany); Leyens, Christoph, E-mail: christoph.leyens@tu-dresden.de [Technical University of Dresden, Institute of Materials Science, Chair of Materials Technology, Berndt-Bau, Helmholtzstr. 7, D-01062 Dresden (Germany)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer The microstructure and hardness of deposited Ti-6Al-4V blocks are investigated. Black-Right-Pointing-Pointer Hardness is influenced by post heat treatment rather than by process parameters. Black-Right-Pointing-Pointer Microstructure within the prior {beta}-grains varies to some extent from grain to grain. Black-Right-Pointing-Pointer A 600 Degree-Sign C/4 h treatment significantly increased the average hardness. - Abstract: Additive layer manufacturing offers a potential for time and cost savings, especially for aerospace components made from costly titanium alloys. In this paper, the morphology, microstructure, chemical composition, and hardness of additive manufactured Ti-6Al-4V blocks are investigated and discussed. Blocks (7 beads wide, 7 layers high) were deposited using Ti-6Al-4V wire and a Nd:YAG laser. Two different sets of parameters are used and three different post heat treatment conditions (as-built, 600 Degree-Sign C/4 h, 1200 Degree-Sign C/2 h) are investigated. The experiments reveal elementary properties of additive manufactured Ti-6Al-4V material in correlation to process parameters and heat treatments, which are discussed comprehensively.

  7. Performance enhancement of perovskite solar cells with Mg-doped TiO2 compact film as the hole-blocking layer

    International Nuclear Information System (INIS)

    In this letter, we report perovskite solar cells with thin dense Mg-doped TiO2 as hole-blocking layers (HBLs), which outperform cells using TiO2 HBLs in several ways: higher open-circuit voltage (Voc) (1.08 V), power conversion efficiency (12.28%), short-circuit current, and fill factor. These properties improvements are attributed to the better properties of Mg-modulated TiO2 as compared to TiO2 such as better optical transmission properties, upshifted conduction band minimum (CBM) and downshifted valence band maximum (VBM), better hole-blocking effect, and higher electron life time. The higher-lying CBM due to the modulation with wider band gap MgO and the formation of magnesium oxide and magnesium hydroxides together resulted in an increment of Voc. In addition, the Mg-modulated TiO2 with lower VBM played a better role in the hole-blocking. The HBL with modulated band position provided better electron transport and hole blocking effects within the device

  8. High breakdown voltage in AlGaN/GaN HEMTs using AlGaN/GaN/AlGaN quantum-well electron-blocking layers.

    Science.gov (United States)

    Lee, Ya-Ju; Yao, Yung-Chi; Huang, Chun-Ying; Lin, Tai-Yuan; Cheng, Li-Lien; Liu, Ching-Yun; Wang, Mei-Tan; Hwang, Jung-Min

    2014-01-01

    In this paper, we numerically study an enhancement of breakdown voltage in AlGaN/GaN high-electron-mobility transistors (HEMTs) by using the AlGaN/GaN/AlGaN quantum-well (QW) electron-blocking layer (EBL) structure. This concept is based on the superior confinement of two-dimensional electron gases (2-DEGs) provided by the QW EBL, resulting in a significant improvement of breakdown voltage and a remarkable suppression of spilling electrons. The electron mobility of 2-DEG is hence enhanced as well. The dependence of thickness and composition of QW EBL on the device breakdown is also evaluated and discussed.

  9. Wind-tunnel experiments of turbulent flow over a surface-mounted 2-D block in a thermally-stratified boundary layer

    Science.gov (United States)

    Zhang, Wei; Markfort, Corey; Porté-Agel, Fernando

    2014-11-01

    Turbulent flows over complex surface topography have been of great interest in the atmospheric science and wind engineering communities. The geometry of the topography, surface roughness and temperature characteristics as well as the atmospheric thermal stability play important roles in determining momentum and scalar flux distribution. Studies of turbulent flow over simplified topography models, under neutrally stratified boundary-layer conditions, have provided insights into fluid dynamics. However, atmospheric thermal stability has rarely been considered in laboratory experiments, e.g., wind-tunnel experiments. Series of wind-tunnel experiments of thermally-stratified boundary-layer flow over a surface-mounted 2-D block, in a well-controlled boundary-layer wind tunnel, will be presented. Measurements using high-resolution PIV, x-wire/cold-wire anemometry and surface heat flux sensors were conducted to quantify the turbulent flow properties, including the size of the recirculation zone, coherent vortex structures and the subsequent boundary layer recovery. Results will be shown to address thermal stability effects on momentum and scalar flux distribution in the wake, as well as dominant mechanism of turbulent kinetic energy generation and consumption. The authors gratefully acknowledge funding from the Swiss National Foundation (Grant 200021-132122), the National Science Foundation (Grant ATM-0854766) and NASA (Grant NNG06GE256).

  10. Effects of the electrode metal structure and the current blocking layer on the characteristics of blue GaN-based light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hee S. [Chonnam National University, Gwangju (Korea, Republic of); LG Innotek Co., Ltd., Paju (Korea, Republic of); Tawfik, Wael Z. [Chonnam National University, Gwangju (Korea, Republic of); Beni-Suef University, Beni-Suef (Egypt); Lee, June K. [Chonnam National University, Gwangju (Korea, Republic of)

    2014-03-15

    The influence of the electrode metal structure and the current blocking layer on the characteristics of blue GaN-based light-emitting diodes (LEDs) was investigated. The changes in the electrode metal structure, along with the current blocking layer (CBL) were found to enable control of the optical and the electrical properties of the fabricated LEDs. Thus, the light output power at an injection current of 90 mA was increased by about 8.5% for the LED with a Cr/Al/Ni/Au electrode metal and a SiO{sub 2} CBL and by about 9.0% for the LED with a Ti/Al/Ni/Au electrode metal and without a SiO{sub 2} CBL over the reference LED with only Cr/Ni/Au electrode metal. This was due to the reduction of the current-crowding effect and to the absorption of photons near the P/N pad by the metal electrode. Furthermore, the operating voltage under the same injection current of 90 mA was changed from 3.30 V for the reference LED to 3.37 V and 3.28 V for the LED with a SiO{sub 2} CBL and for the LED with Ti/Al/Ni/Au electrode metal, respectively. The results confirmed that the electrode metal structure and the CBL played critical roles in the improvement of the emission characteristics in GaN-based LEDs.

  11. Anode interfacial tuning via electron-blocking/hole-transport layers and indium tin oxide surface treatment in bulk-heterojunction organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Hains, Alexander W.; Liu, Jun; Martinson, Alex B.F.; Irwin, Michael D.; Marks, Tobin J. [Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois (United States)

    2010-02-22

    The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and/or a hole-transporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi{sub 2}) and poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current-voltage data in the dark and AM1.5G light show that the TPDSi{sub 2}:TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (V{sub oc}), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi{sub 2}:TFB together in the same cell greatly reduces dark current and produces the highest V{sub oc} (0.91 V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and solvent cleaning markedly affect cell response in combination with each IFL. O{sub 2} plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi{sub 2}:TFB IFL. Solvent cleaning leaves significant residual carbon contamination on the ITO and is best followed by O{sub 2} plasma or UV ozone treatment. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  12. Improved performance of N-face AlGaN-based deep ultraviolet light-emitting diodes with superlattice electron blocking layer

    Science.gov (United States)

    Xie, F.; Wang, F. X.

    2016-08-01

    The performance of N-face AlGaN-based deep ultraviolet light-emitting diodes (UV LEDs) with superlattice electron blocking layer (EBL) is investigated by using two-dimensional numerical simulation. The simulated results demonstrate that the adoption of N-face UV LED with superlattice EBL is critical to improve the device's performance. In comparison with the Ga-face UV LEDs with superlattice and conventional EBL, the N-face device structure with superlattice EBL possesses numerous advantages. By detailedly analyzing the profiles of energy band diagrams, distribution of carrier concentration, and radiative recombination rate, the advantages of N-face UV LED with superlattice EBL are attributed to the higher barrier for electron leakage, and simultaneously reduced barrier for hole injection compared with conventional Ga-face UV LEDs.

  13. Preparation, Structure and Properties of 3D Supramolecular Architecture, on the Basis of Hydrogen Bonds and π-π Stacking Between 2D Layers, with Windmill Building Blocks

    Institute of Scientific and Technical Information of China (English)

    YU Li-qiong; HUANG Ru-dan; CHI Ying-nan; HU Chang-wen

    2008-01-01

    A novel three-dimensional(3D) supramolecular architecture, {[Nd(OH-BDC)(OH-HBDC)(H2O)2]·2H2O}n(1)(OH-H2BDC=5-hydroxyisophthalic acid), which was formed through hydrogen bonds and π-π stacking between two-dimensional(2D)layers, was hydrothermally synthesized and characterized by single-crystal X-ray diffraction.Windmill building blocks, which consist of two nine-coordinated metal centers and four OH-H2BDC groups are along the [100] direction. An observed intense blue luminescence with an emission band peaked at 390 nm for compound 1 may results from ligand-to-metal charge transfer(LMCT). Variable-temperature magnetic susceptibility of compound 1 was investigated and the value was deviated from the Curie-Weiss law.

  14. Performance improvement of blue light-emitting diodes with an AlInN/GaN superlattice electron-blocking layer

    Institute of Scientific and Technical Information of China (English)

    Zhao Fang; Yao Guang-Rui; Song Jing-Jing; Ding Bin-Bin; Xiong Jian-Yong; Su Chen; Zheng Shu-Wen

    2013-01-01

    The characteristics of a blue light-emitting diode (LED) with an AlInN/GaN superlattice (SL) electron-blocking layer (EBL) are analyzed numerically.The cartier concentrations in the quantum wells,energy band diagrams,electrostatic fields,and internal quantum efficiency are investigated.The results suggest that the LED with an AlInN/GaN SL EBL has better hole injection efficiency,lower electron leakage,and smaller electrostatic fields in the active region than the LED with a conventional rectangular AlGaN EBL or a A1GaN/GaN SL EBL.The results also indicate that the efficiency droop is markedly improved when an AlInN/GaN SL EBL is used.

  15. Effect of the microstructural characteristics of a Ga-doped TiO2 hole block layer on an inverted structure organic solar cell

    Science.gov (United States)

    Lee, Eun Ju; Ryu, Sang Ouk

    2016-09-01

    Inverted-structure organic solar cells (OSCs) were fabricated using atomic-layer-deposition (ALD) processed Ga-doped TiO2 as hole blocking layer (HBL). Measured photovoltaic efficiencies were greatly related to the crystallinity of the TiO2 films. However, the efficiencies of the OSCs and the crystallinity of the HBL did not show a linear relationship. The HBL was fully crystallized at a deposition temperature of 200 °C or above, and the power conversion efficiency was measured to be 2.7% with for the HBL processed at 200 °C, but the efficiency decreased to 2.4% for the HBL processed at 250 °C. On the other hand, the surface roughness of the crystallized films was found be increased to two fold in the studied temperature range. Once the HBL had been fully crystallized, the major factor that determined the overall performance of OSCs was the surface roughness of the HBL.

  16. High-efficiency hole extraction/electron-blocking layer to replace poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) in bulk-heterojunction polymer solar cells

    Science.gov (United States)

    Hains, Alexander W.; Marks, Tobin J.

    2008-01-01

    An anode interfacial layer is reported for bulk-heterojunction (BHJ) polymer solar cells to replace the commonly used poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). A poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB)+4,4'-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl (TPDSi2) blend is crosslinked, forming robust ˜10nm thick films covalently bound to indium tin oxide, which transport holes while blocking misdirected electrons. The thermal stability and photovoltaic performance metrics of TFB :TPDSi2-modified BHJ cells are significantly greater than those of cells fabricated in parallel with PEDOT:PSS or with no interfacial layer. For a poly[2-methoxy-5-(3',7'-dimethyloctyloxyl]-1,4-phenylene vinylene: methanofullerene[6 6]-phenyl C61-butyric acid methyl ester cell, Voc=0.89V, Jsc=4.62mA/cm2, FF =54.4%, and ηp=2.23%.

  17. Enhanced light output power in InGaN/GaN light-emitting diodes with a high reflective current blocking layer

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaojie; Yang Ruixia; Wang Jinghui

    2012-01-01

    The light output power of an InGaN/GaN light-emitting diode is improved by using a SiO2/TiO2 distributed Bragg reflector (DBR) and an Al mirror as a hybrid reflective current blocking layer (CBL),Such a hybrid reflective CBL not only plays the role of the CBL by enhancing current spreading but also plays the role of a reflector by preventing photons near the p-electrode pad from being absorbed by a metal electrode.At a wavelength of 455 nm,a 1.5-pair of SiO2/TiO2 DBR and an Al mirror (i.e.1.5 -pair DBR+Al) deposited on a p-GaN layer showed a normal-incidence reflectivity as high as 97.8%.With 20 mA current injection,it was found that the output power was 25.26,24.45,23.58 and 22.45 mW for the LED with a 1.5-pair DBR+Al CBL,a 3 pair DBR CBL,SiO2 CBL and without a CBL,respectively.

  18. Size-tuned ZnO nanocrucible arrays for magnetic nanodot synthesis via atomic layer deposition-assisted block polymer lithography.

    Science.gov (United States)

    Lin, Chun-Hao; Polisetty, Srinivas; O'Brien, Liam; Baruth, Andrew; Hillmyer, Marc A; Leighton, Chris; Gladfelter, Wayne L

    2015-02-24

    Low-temperature atomic layer deposition of conformal ZnO on a self-assembled block polymer lithographic template comprising well-ordered, vertically aligned cylindrical pores within a poly(styrene) (PS) matrix was used to produce nanocrucible templates with pore diameters tunable via ZnO thickness. Starting from a PS template with a hexagonal array of 30 nm diameter pores on a 45 nm pitch, the ZnO thickness was progressively increased to narrow the pore diameter to as low as 14 nm. Upon removal of the PS by heat treatment in air at 500 °C to form an array of size-tunable ZnO nanocrucibles, permalloy (Ni80Fe20) was evaporated at normal incidence, filling the pores and creating an overlayer. Argon ion beam milling was then used to etch back the overlayer (a Damascene-type process), leaving a well-ordered array of isolated ZnO nanocrucibles filled with permalloy nanodots. Microscopy and temperature-dependent magnetometry verified the diameter reduction with increasing ZnO thickness. The largest diameter (30 nm) dots exhibit a ferromagnetic multidomain/vortex state at 300 K, with relatively weakly temperature-dependent coercivity. Reducing the diameter leads to a crossover to a single-domain state and eventually superparamagnetism at sufficiently high temperature, in quantitative agreement with expectations. We argue that this approach could render this form of block polymer lithography compatible with high-temperature processing (as required for technologically important high perpendicular anisotropy ordered alloys, for instance), in addition to enabling separation-dependent studies to probe interdot magnetostatic interactions.

  19. Efficient blue-green and green electroluminescent devices obtained by doping iridium complexes into hole-block material as supplementary light-emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liang [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zheng, Youxuan, E-mail: yxzheng@mail.nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Deng, Ruiping; Feng, Jing; Song, Mingxing; Hao, Zhaomin [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zhang, Hongjie, E-mail: hongjie@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Zuo, Jinglin; You, Xiaozeng [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2014-04-15

    In this work, organic electroluminescent (EL) devices with dominant and supplementary light-emitting layers (EMLs) were designed to further improve the EL performances of two iridium{sup III}-based phosphorescent complexes, which have been reported to provide EL devices with slow EL efficiency roll-off. The widely used hole-block material 2,2′,2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) was selected as host material to construct the supplementary EML. Compared with single-EML devices, double-EMLs devices showed higher EL efficiencies, higher brightness, and lower operation voltage attributed to wider recombination zone and better balance of carriers. In addition, the insertion of supplementary EML is instrumental in facilitating carriers trapping, thus improving the color purity. Finally, high performance blue-green and green EL devices with maximum current efficiencies of 35.22 and 90.68 cd/A, maximum power efficiencies of 26.36 and 98.18 lm/W, and maximum brightness of 56,678 and 112,352 cd/m{sup 2}, respectively, were obtained by optimizing the doping concentrations. Such a device design strategy extends the application of a double EML device structure and provides a chance to simplify device fabrication processes. -- Highlights: • Electroluminescent devices with supplementary light-emitting layer were fabricated. • Doping concentrations and thicknesses were optimized. • Better balance of holes and electrons causes the enhanced efficiency. • Improved carrier trapping suppresses the emission of host material.

  20. Improving hole injection and carrier distribution in InGaN light-emitting diodes by removing the electron blocking layer and including a unique last quantum barrier

    International Nuclear Information System (INIS)

    The effects of removing the AlGaN electron blocking layer (EBL), and using a last quantum barrier (LQB) with a unique design in conventional blue InGaN light-emitting diodes (LEDs), were investigated through simulations. Compared with the conventional LED design that contained a GaN LQB and an AlGaN EBL, the LED that contained an AlGaN LQB with a graded-composition and no EBL exhibited enhanced optical performance and less efficiency droop. This effect was caused by an enhanced electron confinement and hole injection efficiency. Furthermore, when the AlGaN LQB was replaced with a triangular graded-composition, the performance improved further and the efficiency droop was lowered. The simulation results indicated that the enhanced hole injection efficiency and uniform distribution of carriers observed in the quantum wells were caused by the smoothing and thinning of the potential barrier for the holes. This allowed a greater number of holes to tunnel into the quantum wells from the p-type regions in the proposed LED structure

  1. Improved performance of near UV light-emitting diodes with a composition-graded p-AlGaN irregular sawtooth electron-blocking layer

    Science.gov (United States)

    Qin, Ping; Song, Wei-Dong; Hu, Wen-Xiao; Zhang, Yuan-Wen; Zhang, Chong-Zhen; Wang, Ru-Peng; Zhao, Liang-Liang; Xia, Chao; Yuan, Song-Yang; Yin, Yi-an; Li, Shu-Ti; Su, Shi-Chen

    2016-08-01

    We investigate the performances of the near-ultraviolet (about 350 nm–360 nm) light-emitting diodes (LEDs) each with specifically designed irregular sawtooth electron blocking layer (EBL) by using the APSYS simulation program. The internal quantum efficiencies (IQEs), light output powers, carrier concentrations in the quantum wells, energy-band diagrams, and electrostatic fields are analyzed carefully. The results indicate that the LEDs with composition-graded p-Al x Ga1‑x N irregular sawtooth EBLs have better performances than their counterparts with stationary component p-AlGaN EBLs. The improvements can be attributed to the improved polarization field in EBL and active region as well as the alleviation of band bending in the EBL/p-AlGaN interface, which results in less electron leakage and better hole injection efficiency, thus reducing efficiency droop and enhancing the radiative recombination rate. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474105 and 51172079), the Science and Technology Program of Guangdong Province, China (Grant Nos. 2015B090903078 and 2015B010105011), the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT13064), the Science and Technology Project of Guangzhou City, China (Grant No. 201607010246), and the Science and Technology Planning Project of Guangdong Province, China (Grant No. 2015A010105025).

  2. On autoclaved aerated concrete block wall and plaster layer anti-crack%浅谈蒸压加气混凝土砌块墙体及粉刷层防裂

    Institute of Scientific and Technical Information of China (English)

    林恩凯

    2009-01-01

    According to the comparison on characteristics of the autoclaved aerated concrete block and traditional red brick, the author analyzes causes of wall crack quality common diseases, and provides corresponding control measures, so as to solve the crack problem of the autoclaved aerated concrete block wall and the plaster layer, thus promoting application of the autoclaved aerated concrete block.%通过比较蒸压加气混凝土砌块与传统红砖的特性,分析其墙体裂缝质量通病的原因,并提出相应的控制措施,以解决蒸压加气混凝土砌块墙体及粉刷层的开裂问题,从而推广蒸压加气混凝土砌块的应用.

  3. Heart Block

    Science.gov (United States)

    ... the signal causes the heart to contract and pump blood. Heart block occurs if the electrical signal is ... degree heart block limits the heart's ability to pump blood to the rest of the body. This type ...

  4. Population Blocks.

    Science.gov (United States)

    Smith, Martin H.

    1992-01-01

    Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

  5. 三肇凹陷葡萄花油层已开发区块综合评价方法研究%The Study of Comprehensive Evaluation Method for Developed Blocks of Putaohua Oil Layer in Sanzhao Depression

    Institute of Scientific and Technical Information of China (English)

    刘吉余; 王剑; 刘琦

    2011-01-01

    三肇凹陷葡萄花油层地质条件复杂、区块较多.在评价单元划分的基础上,结合研究区的具体地质特征和开发动态特征,采用聚类分析方法,结合各参数的地质意义和开发意义,优选出6个地质参数和4个开发参数.在单因素评价的基础上,针对单因素分类评价存在的分类结果不唯一问题,进行了多因素综合定量评价,并建立分类标准,根据分类标准可以将三肇凹陷葡萄花油层已开发区块划分为三类.Ⅰ类区块在地质上和开发上好于Ⅱ类区块,Ⅱ类区块优于Ⅲ类区块,分类评价结果与实际地质特征和开发特征相符合.%With complicated geological conditions, Putaohua oil layer in Sanzhao depression has lots of blocks.On the basis of evaluation unit division, geological characteristics and development dynamic characteristics, combined with the significance of geological parameters and development parameters, The method of cluster analysis and optimized 6 geological parameters and 4 development parameters is adopted.As the classification of single factor evaluation has not the only result, the multi-factor comprehensive quantitative evaluation is adopted to set up the classification standard.According to the classification standard, the developed blocks of Putaohua oil layer in Sanzhao depression are divided into three types including Ⅰ , Ⅱ and Ⅲ class blocks.As a result of classification evaluation, the geology and development of Ⅰ class blocks are better than Ⅱ class blocks as well as Ⅱ class blocks are better than Ⅲ class blocks, which is close to actual geological characteristics and development characteristics.

  6. Express method of gamma-ray analysis of the soil blocks which have been sampled without a disturbance of the turf layer

    CERN Document Server

    Tertyshnik, E G

    2012-01-01

    This paper presents method of gamma-analysis of the soil patterns sampled soon after of nuclear accident. The method does not require of sample preparation and intends for analysis of the soil samples with a non-homogeneous distribution of activity at the depth. Technique of calibration of the detector efficiency is considered, that have been used when soil blocks sampling by means of the non-disturbance method (by rings) after Chernobyl accident were measured.

  7. Block storage subsystem performance analysis

    CERN Document Server

    CERN. Geneva

    2016-01-01

    You feel that your service is slow because of the storage subsystem? But there are too many abstraction layers between your software and the raw block device for you to debug all this pile... Let's dive on the platters and check out how the block storage sees your I/Os! We can even figure out what those patterns are meaning.

  8. Zitongxi Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ Zitongxi Block (Western Zitong Block), is located in Zitong County, northwest of Sichuan Province (as shown on Fig. 8 ). Geologically. it is situated in the Zitong Depression, southwest of the middle Longmenshan faulted and folded belt, covering an area of 1 830 km2. Transportation is very convenient. A crisscross network of highways run through the block and the Baocheng railway is nearby. The climate is moderate. Most area belongs to hilly land with the elevation of 500-600 m.The Tongjiang River runs across the area.

  9. Optical and electronic proprieties of thin films based on (Z-5-(4-chlorobenzylidene-3-(2-ethoxyphenyl-2 thioxothiazolidin-4-one, (CBBTZ and possible application as exciton-blocking layer in heterojunction organic solar cells

    Directory of Open Access Journals (Sweden)

    Morsli M.

    2012-06-01

    Full Text Available In this work, organic thin film solar cells with structures based on CuPc/C60 bulk heterojunctions, have been fabricated and characterized. The effect of introducing an exciton blocking layer (EBL between the active layer and the metal layer in the solar cell was investigated. For that (Z-5-(4-chlorobenzylidene-3-(2-ethoxyphenyl-2-thioxothiazolidin-4-one, that we called (CBBTZ has been synthesized, characterized and probed as EBL. It was shown that optimized structures containing EBLs resulted in an improvement in solar cell conversion efficiencies. The energy levels corresponding to the highest occupied molecular orbital (HOMO and the lowest unoccupied molecular orbital (LUMO of the CBBTZ have been determined from the first oxidation and reduction potential respectively, using cyclic voltametric (CV measurements. From CV curves, CBBTZ in dichloromethane showed a one electron reversible reduction and oxidation waves. The values of its HOMO and LUMO have been estimated to be 6.42 eV and 3.42 eV respectively. Such values show that CBBTZ could be probed as EBL in organic solar cells based on the ED/EA couple copper phthalocyanine(CuPc/fullerene (C60. The photovoltaic solar cells have been obtained by sequential deposition under vacuum of the different films where their thicknesses were measured in situ by a quartz monitor. When obtained, the averaged efficiency of the cells using the CBBTZ is higher than that achieved without EBL layer.

  10. Atomic Layer Deposition of TiO2 for a High-Efficiency Hole-Blocking Layer in Hole-Conductor-Free Perovskite Solar Cells Processed in Ambient Air.

    Science.gov (United States)

    Hu, Hang; Dong, Binghai; Hu, Huating; Chen, Fengxiang; Kong, Mengqin; Zhang, Qiuping; Luo, Tianyue; Zhao, Li; Guo, Zhiguang; Li, Jing; Xu, Zuxun; Wang, Shimin; Eder, Dominik; Wan, Li

    2016-07-20

    In this study we design and construct high-efficiency, low-cost, highly stable, hole-conductor-free, solid-state perovskite solar cells, with TiO2 as the electron transport layer (ETL) and carbon as the hole collection layer, in ambient air. First, uniform, pinhole-free TiO2 films of various thicknesses were deposited on fluorine-doped tin oxide (FTO) electrodes by atomic layer deposition (ALD) technology. Based on these TiO2 films, a series of hole-conductor-free perovskite solar cells (PSCs) with carbon as the counter electrode were fabricated in ambient air, and the effect of thickness of TiO2 compact film on the device performance was investigated in detail. It was found that the performance of PSCs depends on the thickness of the compact layer due to the difference in surface roughness, transmittance, charge transport resistance, electron-hole recombination rate, and the charge lifetime. The best-performance devices based on optimized TiO2 compact film (by 2000 cycles ALD) can achieve power conversion efficiencies (PCEs) of as high as 7.82%. Furthermore, they can maintain over 96% of their initial PCE after 651 h (about 1 month) storage in ambient air, thus exhibiting excellent long-term stability. PMID:27340730

  11. Atomic Layer Deposition of TiO2 for a High-Efficiency Hole-Blocking Layer in Hole-Conductor-Free Perovskite Solar Cells Processed in Ambient Air.

    Science.gov (United States)

    Hu, Hang; Dong, Binghai; Hu, Huating; Chen, Fengxiang; Kong, Mengqin; Zhang, Qiuping; Luo, Tianyue; Zhao, Li; Guo, Zhiguang; Li, Jing; Xu, Zuxun; Wang, Shimin; Eder, Dominik; Wan, Li

    2016-07-20

    In this study we design and construct high-efficiency, low-cost, highly stable, hole-conductor-free, solid-state perovskite solar cells, with TiO2 as the electron transport layer (ETL) and carbon as the hole collection layer, in ambient air. First, uniform, pinhole-free TiO2 films of various thicknesses were deposited on fluorine-doped tin oxide (FTO) electrodes by atomic layer deposition (ALD) technology. Based on these TiO2 films, a series of hole-conductor-free perovskite solar cells (PSCs) with carbon as the counter electrode were fabricated in ambient air, and the effect of thickness of TiO2 compact film on the device performance was investigated in detail. It was found that the performance of PSCs depends on the thickness of the compact layer due to the difference in surface roughness, transmittance, charge transport resistance, electron-hole recombination rate, and the charge lifetime. The best-performance devices based on optimized TiO2 compact film (by 2000 cycles ALD) can achieve power conversion efficiencies (PCEs) of as high as 7.82%. Furthermore, they can maintain over 96% of their initial PCE after 651 h (about 1 month) storage in ambient air, thus exhibiting excellent long-term stability.

  12. THE THICKNESS DEPENDENCE OF OXYGEN PERMEABILITY IN SOL-GEL DERIVED CGO-COFE2O4 THIN FILMS ON POROUS CERAMIC SUBSTRATES: A SPUTTERED BLOCKING LAYER FOR THICKNESS CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, K

    2009-01-08

    Mixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membrane is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce{sub 0.8}Gd{sub 0.2}O{sub 2-{delta}} (CGO)-CoFe{sub 2}O{sub 4} (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ {approx} 50 nm sputtered CeO{sub 2} layers on the surface of porous CGO ceramic substrates which serve as solution 'blocking' layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of {approx} 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03 {micro}mol/cm{sup 2} s) at 800 C as compared to 1mm thick bulk ceramic membranes (0.003 {micro}mol/cm{sup 2}).

  13. Ghost Block

    OpenAIRE

    Webb, Neil

    2011-01-01

    Filmed on the English south coast 'Ghost Block' depicts the uncanny and eerie atmosphere at the site of a WW2 coastal defence line. The concrete cubes were used as an anti-invasion blockade against potential landing forces. This protection line now slowly decaying and becoming enmeshed into the environment still acts as a defence to repel unwanted visitors. The area is a natural reserve to nesting birds that often lay eggs directly onto the beach surface. The blocks act as a final barrier ...

  14. Epidural block

    Science.gov (United States)

    ... Drugs & Supplements Videos & Tools Español You Are Here: Home ... It numbs or causes a loss of feeling in the lower half your body. This lessens the pain of contractions during childbirth. An epidural block may also be used to ...

  15. 分组密码二元扩散结构的几点注记%Several Properties of Binary Diffusion Layers for Block Cipher

    Institute of Scientific and Technical Information of China (English)

    崔霆; 陈河山; 金晨辉

    2012-01-01

    0-1矩阵常用于设计分组密码的扩散结构,首先证明,当GF(2n)上的矩阵重新定义在扩域GF(2mn)上时其分支教保持不变,据此补充了Choy等人关于GF(2n)上二元矩阵分支数上界的证明.构造了一批分支数达到最优的8阶二元可逆矩阵,给出了一类差分分支数和线性分支数相等的二元可逆矩阵,并从中搜索出了大量16阶分支数达到最优的二元矩阵和对合二元矩阵.%0-1 matrices are often-used in the design of diffusion structures in block ciphers. This paper first proves that the branch number of matrix over GF(2n) does not change while it is redefined over the extension field GF(2mn). By this result, the study reinforces the proof given by Choy et al., which is about the upper bound of branch number of binary matrices over GF(2n). This paper constructs a kind of invertible binary matrices with size 8 and largest branch number, proposes a kind of matrices with equal differential branch number and linear branch number, and also includes lots of matrices and involution matrices with order 16 and optimal branch number with this structure are searched out.

  16. Modelling of current-voltage characteristics of infrared photo-detectors based on type – II InAs/GaSb super-lattice diodes with unipolar blocking layers

    Directory of Open Access Journals (Sweden)

    Vishnu Gopal

    2015-09-01

    Full Text Available It is shown that current-voltage characteristics of infrared photo-detectors based on type-II InAs/GaSb super-lattices with uni-polar blocking layers can be modelled similar to a junction diode with a finite series resistance on account of blocking barriers. As an example this paper presents the results of a study of current-voltage characteristics of a type II InAs/GaSb super-lattice diode with PbIbN architecture using a recently proposed [J. Appl. Phys. 116, 084502 (2014] method for modelling of illuminated photovoltaic detectors. The thermal diffusion, generation – recombination (g-r, and ohmic currents are found as principal components besides a component of photocurrent due to background illumination. The experimentally observed reverse bias diode current in excess of thermal current (diffusion + g-r, photo-current and ohmic shunt current is reported to be best described by an exponential function of the type, Iexcess = Ir0 + K1exp(K2 V, where Ir0, K1 and K2 are fitting parameters and V is the applied bias voltage. The present investigations suggest that the exponential growth of excess current with the applied bias voltage may be taking place along the localized regions in the diode. These localized regions are the shunt resistance paths on account of the surface leakage currents and/or defects and dislocations in the base of the diode.

  17. Computational fluid dynamics analysis of core bypass flow and crossflow in a prismatic very high temperature gas-cooled nuclear reactor based on a two-layer block model

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huhu, E-mail: huhuwang@tamu.edu [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77840 (United States); Dominguez-Ontiveros, Elvis, E-mail: elvisdom@tamu.edu [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77840 (United States); Hassan, Yassin A., E-mail: y-hassan@tamu.edu [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77840 (United States); Department of Mechanical Engineering, Texas A and M University, 3123 TAMU, College Station, TX 77840 (United States)

    2014-03-15

    Highlights: • A CFD model was built based on a two-layer block experimental facility at Texas A and M University. • The coolant characterizations within the uniform and wedge-shaped crossflow gap regions were investigated. • The influence on the coolant distribution from the bypass flow gap width was studied. • Discretization and iterative errors involved in the simulations were quantified. - Abstract: The very high temperature gas-cooled nuclear reactor (VHTR) has been designated as one of the promising reactors that will serve for the Next Generation (Generation IV) Nuclear Plant. For a prismatic VHTR core, the bypass flow and crossflow phenomena are important design considerations. To investigate the coolant distribution in the reactor core based on the two-layer block facility built at Texas A and M University, a three-dimensional steady-state CFD analysis was performed using the commercial code STAR-CCM+ v6.04. Results from this work serve as a guideline and validating source for the related experiments. A grid independence study was conducted to quantify related errors in the simulations. The simulation results show that the bypass flow fraction was not a strong function of the Reynolds number. The presence of the crossflow gap had a significant effect on the distribution of the coolant in the core. Uniform and wedge-shape crossflow gaps were studied. It was found that a significant secondary flow in the crossflow gap region moved from the bypass flow gap toward coolant holes, which resulted in up to a 28% reduction of the coolant mass flow rate in the bypass flow gap.

  18. Electronic structures of (Pb sub 2 Cu)Sr sub 2 Eu sub x Ce sub n sub - sub x Cu sub 2 O sub 2 sub n sub + sub 6 (n=2, 3): Effect of fluorite blocks between adjacent CuO sub 2 layers

    CERN Document Server

    Arai, M

    2003-01-01

    The electronic structures of (Pb sub 2 Cu)Sr sub 2 Eu sub x Ce sub n sub - sub x Cu sub 2 O sub 2 sub n sub + sub 6 (n = 2, 3) compounds which have fluorite blocks between two adjacent CuO sub 2 layers have been studied by using ab-initio method. It is found that the anisotropy is enhanced by inserting the fluorite blocks. The Fermi velocity perpendicular to the CuO sub 2 layers decreases as the thickness of fluorite blocks increases. The Eu substitution is found to affect both the atomic positions and electronic structures. The distance between apical oxygen and copper becomes shorter by the Eu substitution. The energy bands derived from oxygens in the fluorite blocks approach Fermi energy as the content of Eu substitution increases. (author)

  19. Huhe Block

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    @@ Huhe Block is located in the mid-west part of Inner Mogolia Autonomous Region, covering an area of 15 079km2, in the range of 109°40'-112°00'E and 39°23()-40°40'N. Topographically. the Fengzhen hill is to the east, the Yinshan Mounts is to the north, the Hetao Plain and Ordos Plateau are respectively in its west and south.The Yellow River flows across this block. The elevation is 1 000 m in the flat area and in the range of 1 000-1 300m. in the plateau area, good for the development of agriculture and industry as well as husbandry. It belongs to inland plateau climate with annually averaged temperature of 8℃, the minimum being -12℃ in winter and the maximum 22℃ in summer.

  20. Remarkable charge-trapping performance based in Zr0.5Hf0.5O2 with nanocrystal Ba0.6Sr0.4TiO3 blocking layer for nonvolatile memory device

    Science.gov (United States)

    Yan, X. B.; Jia, X. L.; Yang, T.; Zhao, J. H.; Li, Y. C.; Zhou, Z. Y.; Zhang, Y. Y.

    2016-10-01

    Two kinds of charge trapping memory device with Au/Zr0.5Hf0.5O2(ZHO)/SiO2/p-Si and Au/Ba0.6Sr0.4TiO3(BST)/Zr0.5Hf0.5O2/SiO2/p-Si structure were fabricated and investigated. The double BST/ZHO films exhibit a larger memory window of 7.36 V under ±14 V sweeping voltages in its C-V curve and the device has good charge retention properties with only small charge loss of ∼ 5% after more than 104 s. The good characteristics are attributed to the inter-diffusion between BST and ZHO where more deep defect sites were created after RTA treatment, which provides high potential barriers for the trapped charges to tunnel back to the silicon substrate. Furthermore, the nanocrystal in the BST layer increases the tunneling barrier of tunneling current into the gate and effectively restrains the leakage of storage charge from blocking layer, which improves the charge retention characteristic.

  1. Cutaneous Sensory Block Area, Muscle-Relaxing Effect, and Block Duration of the Transversus Abdominis Plane Block

    DEFF Research Database (Denmark)

    Støving, Kion; Rothe, Christian; Rosenstock, Charlotte V;

    2015-01-01

    BACKGROUND AND OBJECTIVES: The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration. METHODS: Sixteen...... healthy volunteers were randomized to receive an ultrasound-guided unilateral TAP block with 20 mL 7.5 mg/mL ropivacaine and placebo on the contralateral side. Measurements were performed at baseline and 90 minutes after performing the block. Cutaneous sensory block area was mapped and separated into a...... medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block and...

  2. Enhanced ultraviolet electroluminescence and spectral narrowing from ZnO quantum dots/GaN heterojunction diodes by using high-k HfO{sub 2} electron blocking layer

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Xiaoming; Long, Hao; Wang, Haoning; Chen, Zhao; Wan, Jiawei; Liu, Yuping; Fang, Guojia, E-mail: gjfang@whu.edu.cn [Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Li, Songzhan [Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); School of Electronic and Electrical Engineering, Wuhan Textile University, Wuhan 430073 (China); Feng, Yamin [Department of Physics, Institute of Nanoscience and Nanotechnology, Central China Normal University, Wuhan 430079 (China); Ouyang, Yifang [College of Physical Science and Technology, Guangxi University, Nanning, Guangxi 530004 (China)

    2014-08-11

    We demonstrated the capability of realizing enhanced ZnO-related UV emissions by using the low-cost and solution-processable ZnO quantum dots (QDs) with the help of a high-k HfO{sub 2} electron blocking layer (EBL) for the ZnO QDs/p-GaN light-emitting diodes (LEDs). Full-width at half maximum of the LED devices was greatly decreased from ∼110 to ∼54 nm, and recombinations related to nonradiative centers were significantly suppressed with inserting HfO{sub 2} EBL. The electroluminescence of the ZnO QDs/HfO{sub 2}/p-GaN LEDs demonstrated an interesting spectral narrowing effect with increasing HfO{sub 2} thickness. The Gaussian fitting revealed that the great enhancement of the Zn{sub i}-related emission at ∼414 nm whereas the deep suppression of the interfacial recombination at ∼477 nm should be the main reason for the spectral narrowing effect.

  3. Study on the blocking effect of a quantum-dot TiO2 compact layer in dye-sensitized solar cells with ionic liquid electrolyte under low-intensity illumination

    Science.gov (United States)

    Zhai, Peng; Lee, Hyeonseok; Huang, Yu-Ting; Wei, Tzu-Chien; Feng, Shien-Ping

    2016-10-01

    In this study, ultrasmall and ultrafine TiO2 quantum dots (QDs) were prepared and used as a high-performance compact layer (CL) in dye-sensitized solar cells (DSCs). We systematically investigated the performance of TiO2 CL under both low-intensity light and indoor fluorescent light illumination and found that the efficiency of DSCs with the insertion of optimal TiO2 QDs-CL was increased up to 18.3% under indoor T5 fluorescent light illumination (7000 lux). We clarified the controversy over the blocking effect of TiO2 CL for the efficiency increment and confirmed that the TiO2 QDs-CL performed significantly better under low-intensity illumination due to the efficient suppression of electron recombination at the FTO/electrolyte interface. We, for the first time, demonstrate this potential for the application of the DSCs with TiO2 QDs-CL in the low-intensity light and indoor fluorescent light illumination.

  4. Graphene Oxide as a Monoatomic Blocking Layer

    DEFF Research Database (Denmark)

    Petersen, Søren; Glyvradal, Magni; Bøggild, Peter;

    2012-01-01

    covered by a compressed mosaic LB film of mGO flakes. These hybrid LB films were examined with atomic force microscopy (AFM) and X-ray reflectivity, both with and without the metal top electrodes. While the AFM enabled surface and morphology analysis, the X-ray reflectivity allowed for a detailed...

  5. EnviroAtlas - Memphis, TN - Block Groups

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Memphis, TN EnviroAtlas community. The block groups are from the US Census Bureau and are included/excluded based...

  6. EnviroAtlas - Austin, TX - Block Groups

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Austin, TX EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...

  7. Ultrasound guided supraclavicular block.

    LENUS (Irish Health Repository)

    Hanumanthaiah, Deepak

    2013-09-01

    Ultrasound guided regional anaesthesia is becoming increasingly popular. The supraclavicular block has been transformed by ultrasound guidance into a potentially safe superficial block. We reviewed the techniques of performing supraclavicular block with special focus on ultrasound guidance.

  8. Skin delivery by block copolymer nanoparticles (block copolymer micelles).

    Science.gov (United States)

    Laredj-Bourezg, Faiza; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Valour, Jean-Pierre; Rovère, Marie-Rose; Smatti, Batoule; Chevalier, Yves

    2015-12-30

    Block copolymer nanoparticles often referred to as "block copolymer micelles" have been assessed as carriers for skin delivery of hydrophobic drugs. Such carriers are based on organic biocompatible and biodegradable materials loaded with hydrophobic drugs: poly(lactide)-block-poly(ethylene glycol) copolymer (PLA-b-PEG) nanoparticles that have a solid hydrophobic core made of glassy poly(d,l-lactide), and poly(caprolactone)-block-poly(ethylene glycol) copolymer (PCL-b-PEG) nanoparticles having a liquid core of polycaprolactone. In vitro skin absorption of all-trans retinol showed a large accumulation of retinol in stratum corneum from both block copolymer nanoparticles, higher by a factor 20 than Polysorbate 80 surfactant micelles and by a factor 80 than oil solution. Additionally, skin absorption from PLA-b-PEG nanoparticles was higher by one order of magnitude than PCL-b-PEG, although their sizes (65nm) and external surface (water-swollen PEG layer) were identical as revealed by detailed structural characterizations. Fluorescence microscopy of histological skin sections provided a non-destructive picture of the storage of Nile Red inside stratum corneum, epidermis and dermis. Though particle cores had a different physical states (solid or liquid as measured by (1)H NMR), the ability of nanoparticles for solubilization of the drug assessed from their Hildebrand solubility parameters appeared the parameter of best relevance regarding skin absorption.

  9. Creative Construction: Unit Blocks.

    Science.gov (United States)

    Texas Child Care, 1999

    1999-01-01

    Describes the use of unit blocks with young children in early childhood education (ECE) settings to expand all areas of the curriculum. Discusses the origin of blocks in ECE programs, presents developmental stages of block play, describes children's building styles, and makes recommendations for getting started in block play for children of…

  10. Electrical Structure of the Crus Beneath the Ordos Block

    Institute of Scientific and Technical Information of China (English)

    Zhao Guoze; Zhan Yan; Wang Lifeng; Wang Jijun; Tang Ji; Chen Xiaobin; Xiao Qibin

    2011-01-01

    The Ordos block is a stable tectonic unit since the Cenozoic. Whether low-resistivity layers exist in the middle and lower crust of this kind block is an open question. This work attempts to reveal the entire crustal structure of the block based on interp

  11. Interfacial and Electrical Characterization of HfO2 Gate Dielectric Film with a Blocking Layer of Al2O3%具有Al2O3阻挡层的HfO2栅介质膜的界面和电学性能的表征

    Institute of Scientific and Technical Information of China (English)

    程新红; 何大伟; 宋朝瑞; 俞跃辉; 沈达身

    2009-01-01

    研究了经过700℃快速热退火的并在Si界面处插入Al2O3阻挡层的HfO2栅介质膜的界面结构和电学性能.X射线光电子谱表明,退火后,界面层中的siOx转化为化学当量的SiO2,而且未发现铪基硅酸盐和铪基酸化物.由电学测试提取出等效栅氧厚度为2.5nm,固定电荷密度为-4.5×1011/cm2.发现Al2O3阻挡层能有效地阻止Si原子扩散进入HfO2薄膜,进而改善HfO2栅介质膜的界面和电学性能.%HfO2 gate dielectric films with a blocking layer of Al2O3 inserted between HfO2 layer and Si layer (HfO2/Si) were treated with rapid thermal annealing process at 700℃. The interracial structure and electrical properties were reported. The results of X-ray photoelectron spectroscopy showed that the interracial layer of SiOx transformed into SiO2 after the annealing treatment, and Hf-silicates and Hf-silicides were not detected. The results of high-resolution transmission electron microscopy indicated that the in-terracial layer was composed of SiO2 for the annealed film with blocking layer. The results of the electrical measurements indicated that the equivalent oxide thickness decreased to 2.5 nm and the fixed charge density decreased to -4.5×1011/cm2 in comparison with the same thickness of HfO2 films without the blocking layer. Al2O3 layer could effectively prevent the diffusion of Si into HfO2 film and improve the interfacial and electrical performance of HfO2 film.

  12. Blocking and associability change.

    Science.gov (United States)

    Jones, Peter M; Haselgrove, Mark

    2013-07-01

    Blocking of learning about a conditioned stimulus (the "blocked" cue) occurs when it is trained alongside an additional stimulus (the "blocking" cue) that has been previously presented with the outcome. A number of theories (e.g., N. J. Mackintosh. 1975a. A Theory of Attention: Variations in the Associability of Stimuli With Reinforcement. Psychological Review, 82, 276-298; J. M. Pearce & G. Hall. 1980. A Model for Pavlovian Learning: Variation in the Effectiveness of Conditioned But Not Unconditioned Stimuli. Psychological Review, 87, 532-552) account for this attenuation in learning by proposing that attention paid to the blocked cue is restricted. In three experiments, we examined the associability of both blocked and blocking cues. In Experiment 1, rats were trained with a blocking protocol before being given a test discrimination composed of two components; one of these components required the use of the previously blocked cue as a discriminative stimulus, and the other component was soluble by using the blocking cue. To our surprise, the component that depended on the blocked cue was more readily solved than the component dependent on the blocking cue. The results of Experiments 2 and 3 suggest that this is due to the quantity of exposure that each stimulus received during initial training. Implications for theories of blocking, and more widely associative learning, are discussed. PMID:23668185

  13. Blocking and associability change.

    Science.gov (United States)

    Jones, Peter M; Haselgrove, Mark

    2013-07-01

    Blocking of learning about a conditioned stimulus (the "blocked" cue) occurs when it is trained alongside an additional stimulus (the "blocking" cue) that has been previously presented with the outcome. A number of theories (e.g., N. J. Mackintosh. 1975a. A Theory of Attention: Variations in the Associability of Stimuli With Reinforcement. Psychological Review, 82, 276-298; J. M. Pearce & G. Hall. 1980. A Model for Pavlovian Learning: Variation in the Effectiveness of Conditioned But Not Unconditioned Stimuli. Psychological Review, 87, 532-552) account for this attenuation in learning by proposing that attention paid to the blocked cue is restricted. In three experiments, we examined the associability of both blocked and blocking cues. In Experiment 1, rats were trained with a blocking protocol before being given a test discrimination composed of two components; one of these components required the use of the previously blocked cue as a discriminative stimulus, and the other component was soluble by using the blocking cue. To our surprise, the component that depended on the blocked cue was more readily solved than the component dependent on the blocking cue. The results of Experiments 2 and 3 suggest that this is due to the quantity of exposure that each stimulus received during initial training. Implications for theories of blocking, and more widely associative learning, are discussed.

  14. Generalized Block Failure

    DEFF Research Database (Denmark)

    Jönsson, Jeppe

    2015-01-01

    Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...... yield lines around the block leads to simple interaction formulas similar to other interaction formulas in the codes.......Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...

  15. Blocked Randomization with Randomly Selected Block Sizes

    Directory of Open Access Journals (Sweden)

    Jimmy Efird

    2010-12-01

    Full Text Available When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes.

  16. Blocked randomization with randomly selected block sizes.

    Science.gov (United States)

    Efird, Jimmy

    2011-01-01

    When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes. PMID:21318011

  17. Improved Performance of Dye-Sensitized Solar Cells Fabricated from a Coumarin NKX-2700 Dye-Sensitized TiO2/MgO Core-Shell Photoanode with an HfO2 Blocking Layer and a Quasi-Solid-State Electrolyte

    Science.gov (United States)

    Maheswari, D.; Venkatachalam, P.

    2015-03-01

    Dye sensitized solar cells (DSSC) were fabricated from a coumarin NKX-2700 dye-sensitized core-shell photoanode and a quasi-solid-state electrolyte, sandwiched together, with a cobalt sulfide-coated counter electrode. The core-shell photoanode consisted of a composite mixture of 90% TiO2 nanoparticles and 10% TiO2 nanowires (TNPW) as core layer and MgO nanoparticles (MNP) as shell layer. Hafnium oxide (HfO2) was applied to the core-shell photoanode film as a blocking layer. TiO2 nanoparticles, TiO2 nanowires, and TNPW/MNP were characterized by x-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. It was apparent from the UV-visible spectrum of the sensitizing dye coumarin NKX-2700 that its absorption was maximum at 525 nm. Power conversion efficiency (PCE) was greater for DSSC-1, fabricated with a core-shell TNPW/MNP/HfO2 photoanode, than for the other DSSC; its photovoltaic properties were: short circuit photocurrent J sc = 19 mA/cm2, open circuit voltage ( V oc) = 720 mV, fill factor ( FF) = 66%, and PCE ( η) = 9.02%. The charge-transport and charge-recombination behavior of the DSSC were investigated by electrochemical impedance spectroscopy; the results showed that the composite core-shell film resulted in the lowest charge-transfer resistance ( R CE) and the longest electron lifetime ( τ eff). Hence, the improved performance of DSSC-1 could be ascribed to the core-shell photoanode with blocking layer, which increased electron transport and suppressed recombination of charge carriers at the photoanode/dye/electrolyte interface.

  18. BLOCK H-MATRICES AND SPECTRUM OF BLOCK MATRICES

    Institute of Scientific and Technical Information of China (English)

    黄廷祝; 黎稳

    2002-01-01

    The block H-matrices are studied by the concept of G-functions, several concepts of block matrices are introduced. Equivalent characters of block H-matrices are obtained. Spectrum localizations claracterized by Gfunctions for block matrices are got.

  19. Lesson Thirteen Trifascicular Block

    Institute of Scientific and Technical Information of China (English)

    鲁端; 王劲

    2005-01-01

    @@ A complete trifascicular block would result in complete AV block. The idio ventricular rhythm has a slower rate and a wide QRS complex because the pacemaker is located at the peripheral part of the conduction system distal to the sites of the block1. Such a rhythm may be difficult to differentiate from bifascicular or bundle branch block combined with complete block at a higher level such as the AV node or His bundle2. Besides a slower ventricular rate, a change in the morphology of the QRS complex from a previous known bifascicular pattern would be strongly suggestive of a trifascicular origin of the complete AV block3. A His bundle recording is required for a definitive diagnosis, however.

  20. Block Advertisement Protocol

    OpenAIRE

    Nemirovsky, Danil

    2015-01-01

    Bitcoin, a decentralized cryptocurrency, has attracted a lot of attention from academia, financial service industry and enthusiasts. The trade-off between transaction confirmation throughput and centralization of hash power do not allow Bitcoin to perform at the same level as modern payment systems. Block Advertisement Protocol is proposed as a step to resolve this issue. The protocol allows block mining and block relaying to happen in parallel. The protocol dictates a miner to advertise the ...

  1. Block Cipher Analysis

    DEFF Research Database (Denmark)

    Miolane, Charlotte Vikkelsø

    ensurethat no attack violatesthe securitybounds specifiedbygeneric attack namely exhaustivekey search and table lookup attacks. This thesis contains a general introduction to cryptography with focus on block ciphers and important block cipher designs, in particular the Advanced Encryption Standard...... on small scale variants of AES. In the final part of the thesis we present a new block cipher proposal Present and examine its security against algebraic and differential cryptanalysis in particular....

  2. Block Scheduling Revisited.

    Science.gov (United States)

    Queen, J. Allen

    2000-01-01

    Successful block scheduling depends on provision of initial and ongoing instructional training. Teaching strategies should vary and include cooperative learning, the case method, the socratic seminar, synectics, concept attainment, the inquiry method, and simulations. Recommendations for maximizing block scheduling are outlined. (Contains 52…

  3. Surviving Block Scheduling.

    Science.gov (United States)

    Haley, Marjorie

    A discussion of block scheduling for second language instruction looks at the advantages and disadvantages and offers some suggestions for classroom management and course organization. It is argued that block scheduling may offer a potential solution to large classes, insufficient time for labs, too little individualized instruction; few…

  4. Feasibility Study of Multi-layer Drainage for Nos.3 and 9 Coal Seams in Shouyang Block, Qinshui Basin%沁水盆地寿阳区块3号和9号煤层合层排采的可行性研究

    Institute of Scientific and Technical Information of China (English)

    王振云; 唐书恒; 孙鹏杰; 郑贵强

    2013-01-01

    The CBM coal reservoirs in the Shouyang block have characteristics of multiple layers, small single layer thickness, low pro-ductivity and hard to exploit. To reduce the cost, improve CBM resource recovery, the multi-layer drainage for the main target Nos. 3 and 9 coal seams is the preferred scheme. Based on the key control factors of vertical well multi-layer drainage systematic analysis, consid-ered that the coal and roof/floor rock mechanical property, reservoir pressure gradient, critical desorption pressure, permeability, coal reservoir fluid supply capacity are the key control factors. According to the CBM well exploration and exploitation data in the area and key control factors analyzed feasibility of multi-layer drainage for Nos.3 and 9 coal seams in the block, and pointed out the most advanta-geous range.%寿阳区块煤储层具有层数多、单层厚度小、产能低、开采难度大的特征,为降低成本、提高煤层气资源采收率,对该区主要目标层3号和9号煤层进行合层开采是制定开发方案时的首选。在系统分析煤层气直井合层排采的关键控制因素基础上,认为煤岩及顶底板岩石力学性质、储层压力梯度、临界解吸压力、渗透率、煤储层供液能力是合层排采的主控因素,根据区内煤层气井勘探开发资料及主控因素分析了区块合层排采的可行性,指出了适合3号和9号煤层合层排采的有利区域。

  5. The Adobe Photoshop layers book

    CERN Document Server

    Lynch, Richard

    2011-01-01

    Layers are the building blocks for working in Photoshop. With the correct use of the Layers Tool, you can edit individual components of your images nondestructively to ensure that your end result is a combination of the best parts of your work. Despite how important it is for successful Photoshop work, the Layers Tool is one of the most often misused and misunderstood features within this powerful software program. This book will show you absolutely everything you need to know to work with layers, including how to use masks, blending, modes and layer management. You'll learn professional tech

  6. Predictability of blocking

    International Nuclear Information System (INIS)

    Tibaldi and Molteni (1990, hereafter referred to as TM) had previously investigated operational blocking predictability by the ECMWF model and the possible relationships between model systematic error and blocking in the winter season of the Northern Hemisphere, using seven years of ECMWF operational archives of analyses and day 1 to 10 forecasts. They showed that fewer blocking episodes than in the real atmosphere were generally simulated by the model, and that this deficiency increased with increasing forecast time. As a consequence of this, a major contribution to the systematic error in the winter season was shown to derive from the inability of the model to properly forecast blocking. In this study, the analysis performed in TM for the first seven winter seasons of the ECMWF operational model is extended to the subsequent five winters, during which model development, reflecting both resolution increases and parametrisation modifications, continued unabated. In addition the objective blocking index developed by TM has been applied to the observed data to study the natural low frequency variability of blocking. The ability to simulate blocking of some climate models has also been tested

  7. Block copolymer battery separator

    Energy Technology Data Exchange (ETDEWEB)

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  8. Blocking in Category Learning

    OpenAIRE

    Bott, Lewis; Hoffman, Aaron B.; Murphy, Gregory L.

    2007-01-01

    Many theories of category learning assume that learning is driven by a need to minimize classification error. When there is no classification error, therefore, learning of individual features should be negligible. We tested this hypothesis by conducting three category learning experiments adapted from an associative learning blocking paradigm. Contrary to an error-driven account of learning, participants learned a wide range of information when they learned about categories, and blocking effe...

  9. High Temperature, Low Relative Humidity, Polymer-type Membranes Based on Disulfonated Poly(arylene ether) Block and Random Copolymers Optionally Incorporating Protonic Conducting Layered Water insoluble Zirconium Fillers

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, James E.; Baird, Donald G.

    2010-06-03

    Our research group has been engaged in the past few years in the synthesis of biphenol based partially disulfonated poly(arylene ether sulfone) random copolymers as potential PEMs. This series of polymers are named as BPSH-xx, where BP stands for biphenol, S stands for sulfonated, H stands for acidified and xx represents the degree of disulfonation. All of these sulfonated copolymers phase separate to form nano scale hydrophilic and hydrophobic morphological domains. The hydrophilic phase containing the sulfonic acid moieties causes the copolymer to absorb water. Water confined in hydrophilic pores in concert with the sulfonic acid groups serve the critical function of proton (ion) conduction and water transport in these systems. Both Nafion and BPSH show high proton conductivity at fully hydrated conditions. However proton transport is especially limited at low hydration level for the BPSH random copolymer. It has been observed that the diffusion coefficients of both water and protons change with the water content of the pore. This change in proton and water transport mechanisms with hydration level has been attributed to the solvation of the acid groups and the amount of bound and bulk-like water within a pore. At low hydration levels most of the water is tightly associated with sulfonic groups and has a low diffusion coefficient. This tends to encourage isolated domain morphology. Thus, although there may be significant concentrations of protons, the transport is limited by the discontinuous morphological structure. Hence the challenge lies in how to modify the chemistry of the polymers to obtain significant protonic conductivity at low hydration levels. This may be possible if one can alter the chemical structure to synthesize nanophase separated ion containing block copolymers. Unlike the BPSH copolymers, where the sulfonic acid groups are randomly distributed along the chain, the multiblock copolymers will feature an ordered sequence of hydrophilic and

  10. Growing Up with Their Blocks.

    Science.gov (United States)

    Winarski, Diana L.

    1995-01-01

    Describes one teacher's use of traditional wooden blocks in fifth-grade curriculum. Notes that use of blocks can teach communication, teamwork, precision, and arithmetic concepts. Also describes four easy classroom block projects. (TM)

  11. Block diagonal and schur complement preconditioners for block-toeplitz systems with small size blocks

    OpenAIRE

    Ching, WK; Ng, MK; Wen, YW

    2007-01-01

    In this paper we consider the solution of Hermitian positive definite block-Toeplitz systems with small size blocks. We propose and study block diagonal and Schur complement preconditioners for such block-Toeplitz matrices. We show that for some block-Toeplitz matrices, the spectra of the preconditioned matrices are uniformly bounded except for a fixed number of outliers where this fixed number depends only on the size of the block. Hence, conjugate gradient type methods, when applied to solv...

  12. Right bundle branch block

    DEFF Research Database (Denmark)

    Bussink, Barbara E; Holst, Anders Gaarsdal; Jespersen, Lasse;

    2013-01-01

    AimsTo determine the prevalence, predictors of newly acquired, and the prognostic value of right bundle branch block (RBBB) and incomplete RBBB (IRBBB) on a resting 12-lead electrocardiogram in men and women from the general population.Methods and resultsWe followed 18 441 participants included.......5%/2.3% in women, P Right bundle branch block was associated with significantly...... increased all-cause and cardiovascular mortality in both genders with age-adjusted hazard ratios (HR) of 1.31 [95% confidence interval (CI), 1.11-1.54] and 1.87 (95% CI, 1.48-2.36) in the gender pooled analysis with little attenuation after multiple adjustment. Right bundle branch block was associated...

  13. Bactericidal block copolymer micelles.

    Science.gov (United States)

    Vyhnalkova, Renata; Eisenberg, Adi; van de Ven, Theo

    2011-05-12

    Block copolymer micelles with bactericidal properties were designed to deactivate pathogens such as E. coli bacteria. The micelles of PS-b-PAA and PS-b-P4VP block copolymers were loaded with biocides TCMTB or TCN up to 20 or 30 wt.-%, depending on the type of antibacterial agent. Bacteria were exposed to loaded micelles and bacterial deactivation was evaluated. The micelles loaded with TCN are bactericidal; bacteria are killed in less than two minutes of exposure. The most likely interpretation of the data is that the biocide is transferred to the bacteria by repeated micelle/bacteria contacts, and not via the solution. PMID:21275041

  14. Effect of the blocking layer prepared by sol-gel method on the double composite TiO2 photo-anode%溶胶-凝胶法制备的阻挡层对双层复合TiO2光阳极性能的影响

    Institute of Scientific and Technical Information of China (English)

    杨春利; 许启明; 宫明; 杨刘; 张笙

    2012-01-01

    The dense TiO2 blocking layer with different thickness was prepared on conductive glass by sol-gel method, and the outer TiO2 porous film was prepared by hydrothermal method. The influence of preparation methods and the thickness of dense barrier films on surface morphology and absorbance were analyzed by field emission scanning electron microscope (FE-SEM) and UV-vis spectrophotometer. In addition, the electrical properties of the DSSC were studied. The results indicate that, when the barrier layer is prepared by sintering each layer, the composite photo-anode possesses a relatively loose surface morphology, and therefore has a maximum absorbance. At the same time, the DSSC presents the best electrical properties. The thickness of the barrier layer has little effect on absorbance and electrical properties, but when the number of barrier layer is 8, the photo-anode has the maximum absorbance and DSSC has the best electrical properties.%用溶胶-凝胶法在导电玻璃上制备不同成膜方式和层厚的TiO2致密膜阻挡层,采用水热法制备外层多孔TiO2薄膜.用场发射扫描电镜(FE-SEM)和紫外-可见分光光度计分析阻挡层成膜方式和层厚对复合光阳极薄膜的表面形貌和吸光度的影响,并研究其对应的DSSC的电学性能.结果表明:阻挡层经层层烧结,复合光阳极具有较疏松的表面形貌,吸光度和DSSC的电学性能最佳;阻挡层的层厚对复合膜的吸光度和DSSC的电学性能影响不大,但层数为8层时具有最好的吸光度和电学性能.

  15. E-Block: A Tangible Programming Tool with Graphical Blocks

    OpenAIRE

    Danli Wang; Yang Zhang; Shengyong Chen

    2013-01-01

    This paper designs a tangible programming tool, E-Block, for children aged 5 to 9 to experience the preliminary understanding of programming by building blocks. With embedded artificial intelligence, the tool defines the programming blocks with the sensors as the input and enables children to write programs to complete the tasks in the computer. The symbol on the programming block's surface is used to help children understanding the function of each block. The sequence information is transfer...

  16. A Place for Block Play.

    Science.gov (United States)

    Moore, Gary T.

    1997-01-01

    Discusses the importance of block play--including its contributions to perceptual, fine motor, and cognitive development--and components of a good preschool block play area. Recommends unit blocks complemented by stacking blocks, toys, beads, cubes, and Brio wooden toys. Makes recommendations for space, size, locations and connections to other…

  17. Natural convection through enclosed disconnected solid blocks

    Energy Technology Data Exchange (ETDEWEB)

    Lao, Fernando Cesar De; Junqueira, Silvio L.M.; Franco, Admilson T. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)]. E-mails: fernandodelai@gmail.com; silvio@utfpr.edu.br; admilson@utfpr.edu.br; Lage, Jose L. [Southern Methodist University (SMU), Dallas, TX (United States)]. E-mail: JLL@smu.edu

    2008-07-01

    In this study, the natural convection inside a fluid filled, enclosure containing several solid obstructions and being heated from the side is modeled and numerically simulated. The solid obstructions are equally spaced, conducting, and disconnected square blocks. The mathematical model is based on the balance equations of mass, momentum and energy, which are then solved numerically via the finite-volume method with the SIMPLEST algorithm and the HYBRID scheme. The effects of varying the solid-fluid thermal conductivity ratio (K), the fluid volume-fraction or porosity ({phi}), the number of solid blocks (N) and the heating strength (represented by the Rayleigh number, Ra) of the enclosure on the Nusselt number based on the surface-averaged heat transfer coefficient along the heated wall of the enclosure are studied. The results indicate a competing effect caused by the proximity of the solid blocks to the heated and cooled walls, vis-a-vis hindering the boundary layer growth, hence reducing the heat transfer effectiveness, and at the same time enhancing the heat transfer when the blocks' thermal conductivity is larger than that of the fluid. An analytical estimate of the minimum number of blocks beyond which the convection hindrance becomes predominant is presented and validated by the numerical results. (author)

  18. Effects of Block Scheduling

    Directory of Open Access Journals (Sweden)

    William R. Veal

    1999-09-01

    Full Text Available This study examined the effects of a tri-schedule on the academic achievement of students in a high school. The tri-schedule consists of traditional, 4x4 block, and hybrid schedules running at the same time in the same high school. Effectiveness of the schedules was determined from the state mandated test of basic skills in reading, language, and mathematics. Students who were in a particular schedule their freshman year were tested at the beginning of their sophomore year. A statistical ANCOVA test was performed using the schedule types as independent variables and cognitive skill index and GPA as covariates. For reading and language, there was no statistically significant difference in test results. There was a statistical difference mathematics-computation. Block mathematics is an ideal format for obtaining more credits in mathematics, but the block format does little for mathematics achievement and conceptual understanding. The results have content specific implications for schools, administrations, and school boards who are considering block scheduling adoption.

  19. Spice Blocks Melanoma Growth

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Curcumin, the pungent yellow spice found in both turmeric and curry powders, blocks a key biological pathway needed for development of melanoma and other cancers, according to a study that appears in the journal Cancer. Researchers from The University of Texas M. D. Anderson Cancer Center demonstrate how curcumin stops laboratory strains of…

  20. Contaminated soil concrete blocks

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.; Limbachiya, Mukesh C.; Kew, Hsein Y.

    2009-01-01

    According to Dutch law the contaminated soil needs to be remediated or immobilised. The main focus in this article is the design of concrete blocks, containing contaminated soil, that are suitable for large production, financial feasible and meets all technical and environmental requirements. In ord

  1. Photocatalytic Nanostructuring of Graphene Guided by Block Copolymer Self-Assembly

    DEFF Research Database (Denmark)

    Wang, Zhongli; Li, Tao; Schulte, Lars;

    2016-01-01

    graphene nanomesh was fabricated by photocatalysis of single-layer graphene suspended on top of TiO2-covered nanopillars, which were produced by combining block copolymer nanolithography with atomic layer deposition. Graphene nanoribbons were also prepared by the same method applied to a line-forming block...

  2. Edit Distance with Block Deletions

    OpenAIRE

    Dana Shapira; Storer, James A.

    2011-01-01

    Several variants of the edit distance problem with block deletions are considered. Polynomial time optimal algorithms are presented for the edit distance with block deletions allowing character insertions and character moves, but without block moves. We show that the edit distance with block moves and block deletions is NP-complete (Nondeterministic Polynomial time problems in which any given solution to such problem can be verified in polynomial time, and any NP problem can be converted into...

  3. Fermion-Scalar Conformal Blocks

    CERN Document Server

    Iliesiu, Luca; Poland, David; Pufu, Silviu S; Simmons-Duffin, David; Yacoby, Ran

    2015-01-01

    We compute the conformal blocks associated with scalar-scalar-fermion-fermion 4-point functions in 3D CFTs. Together with the known scalar conformal blocks, our result completes the task of determining the so-called `seed blocks' in three dimensions. Conformal blocks associated with 4-point functions of operators with arbitrary spins can now be determined from these seed blocks by using known differential operators.

  4. NCCN Evidence Blocks.

    Science.gov (United States)

    Carlson, Robert W; Jonasch, Eric

    2016-05-01

    NCCN has developed a series of Evidence Blocks: graphics that provide ratings for each recommended treatment regimen in terms of efficacy, toxicity, quality and consistency of the supporting data, and affordability. The NCCN Evidence Blocks are currently available in 10 tumor types within the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines). At a glance, patients and providers can understand how a given treatment was assessed by the NCCN Guidelines Panel and get a sense of how a given treatment may match individual needs and preferences. Robert W. Carlson, MD, CEO of NCCN, described the reasoning behind this new feature and how the tool is used, and Eric Jonasch, MD, Professor of Genitourinary Medical Oncology at The University of Texas MD Anderson Cancer Center, and Vice Chair of the NCCN Kidney Cancer Panel, described its applicability in the management of metastatic renal cell carcinoma. PMID:27226499

  5. STRUCTURE OF CRYSTALLINE DOMAINS IN SEMICRYSTALLINE BLOCK COPOLYMER THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    Guo-dong Liang; Jun-ting Xu; Zhi-qiang Fan

    2006-01-01

    Thin film morphology of a symmetric semicrystalline oxyethylene/oxybutylene diblock copolymer (E76B38) on silicon was investigated by tapping mode atomic force microscopy (AFM). It is found that the nascent thin film is composed of multiple polymer layers having mixed thicknesses of L ≈ L0 and L ≈ L0/2 (L0 is the long period of the block copolymer in bulk) besides the first layer near the substrate. This shows that the crystalline domain in the block copolymer consists of double poly(oxyethylene) layers. Annealing leads to disappearance of the polymer layers with thickness L ≈ L0/2, indicating that such polymer layers are metastable.

  6. SUPERFICIAL CERVICAL PLEXUS BLOCK

    Directory of Open Access Journals (Sweden)

    Komang Mega Puspadisari

    2014-01-01

    Full Text Available Superficial cervical plexus block is one of the regional anesthesia in  neck were limited to thesuperficial fascia. Anesthesia is used to relieve pain caused either during or after the surgery iscompleted. This technique can be done by landmark or with ultrasound guiding. The midpointof posterior border of the Sternocleidomastoid was identified and the prosedure done on thatplace or on the level of cartilage cricoid.

  7. Managing access block.

    Science.gov (United States)

    Cameron, Peter; Scown, Paul; Campbell, Donald

    2002-01-01

    There is pessimism regarding the ability of the Acute Health Sector to manage access block for emergency and elective patients. Melbourne Health suffered an acute bed crisis in 2001 resulting in record ambulance diversions and emergency department (ED) delays. We conducted an observational study to reduce access block for emergency patients whilst maintaining elective throughput at Melbourne Health. This involved a clinician-led taskforce using previously proven principles for organisational change to implement 51 actions to improve patient access over a three-month period. The primary outcome measures were ambulance diversion, emergency patients waiting more than 12 hours for an inpatient bed, elective throughput and theatre cancellations. Despite a reduction in multi-day bed numbers all primary objectives were met, ambulance diversion decreased to minimal levels, 12-hour waits decreased by 40% and elective throughput was maintained. Theatre cancellations were also minimised. We conclude that access block can be improved by clinician-led implementation of proven process improvements over a short time frame. The ability to sustain change over the longer term requires further study.

  8. Nanopatterned articles produced using surface-reconstructed block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

    2016-06-07

    Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

  9. Multicompartment Micelles From π-Shaped ABC Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; ZHONG Chong-Li

    2007-01-01

    Dissipative particle dynamics simulations were performed on the morphology and structure of multicompartment micelles formed from n-shaped ABC block copolymers in water. The influences of chain architectures were studied in a systematic way, and a rich variety of morphologies were observed, such as spherical, wormlike,X-shaped, Y-shaped, ribbon-like, layered rod-like, layered disk-like, as well as network morphologies. The simulations show that the distance between the two grafts plays an important role in control of the morphology. Since π-shaped ABC block copolymers can be reduced to linear ABC and star ABC block copolymers, they are good model copolymers for studying the self-assembly of complex block copolymers into micelles. The knowledge obtained in this work as well as the new morphologies identified provide useful information for future rational design and synthesis of novel multicompartment micelles.

  10. E-Block: A Tangible Programming Tool with Graphical Blocks

    Directory of Open Access Journals (Sweden)

    Danli Wang

    2013-01-01

    Full Text Available This paper designs a tangible programming tool, E-Block, for children aged 5 to 9 to experience the preliminary understanding of programming by building blocks. With embedded artificial intelligence, the tool defines the programming blocks with the sensors as the input and enables children to write programs to complete the tasks in the computer. The symbol on the programming block's surface is used to help children understanding the function of each block. The sequence information is transferred to computer by microcomputers and then translated into semantic information. The system applies wireless and infrared technologies and provides user with feedbacks on both screen and programming blocks. Preliminary user studies using observation and user interview methods are shown for E-Block's prototype. The test results prove that E-Block is attractive to children and easy to learn and use. The project also highlights potential advantages of using single chip microcomputer (SCM technology to develop tangible programming tools for children.

  11. Block Transfer Handbook: Constructing and Negotiating Block Transfer Agreements.

    Science.gov (United States)

    Finlay, Finola

    The purpose of this handbook is to provide resources for institutions or articulation committees who are engaged in the task of investigating the feasibility of block transfer agreements. Block transfer is the process whereby a block of credits is granted to students who have successfully completed a certificate, diploma, or cluster of courses…

  12. Demographic Data - MDC_Block

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — A polygon feature class of Miami-Dade Census 2000 Blocks. Census blocks are areas bounded on all sides by visible and/or invisible features shown on a map prepared...

  13. Porous block nanofiber composite filters

    Energy Technology Data Exchange (ETDEWEB)

    Ginley, David S.; Curtis, Calvin J.; Miedaner, Alexander; Weiss, Alan J.; Paddock, Arnold

    2016-08-09

    Porous block nano-fiber composite (110), a filtration system (10) and methods of using the same are disclosed. An exemplary porous block nano-fiber composite (110) includes a porous block (100) having one or more pores (200). The porous block nano-fiber composite (110) also includes a plurality of inorganic nano-fibers (211) formed within at least one of the pores (200).

  14. CORE SATURATION BLOCKING OSCILLATOR

    Science.gov (United States)

    Spinrad, R.J.

    1961-10-17

    A blocking oscillator which relies on core saturation regulation to control the output pulse width is described. In this arrangement an external magnetic loop is provided in which a saturable portion forms the core of a feedback transformer used with the thermionic or semi-conductor active element. A first stationary magnetic loop establishes a level of flux through the saturation portion of the loop. A second adjustable magnet moves the flux level to select a saturation point giving the desired output pulse width. (AEC)

  15. Block coordination copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2014-11-11

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  16. Block coordination copolymers

    Science.gov (United States)

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

    2012-11-13

    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  17. Behaviour of layered sandstone under Brazilian test conditions:Layer orientation and shape effects

    Institute of Scientific and Technical Information of China (English)

    Abbass Tavallali; André Vervoort

    2013-01-01

    The experimental study in this paper focuses on the effects of the layer orientation and sample shape on failure strength and fracture pattern of samples tested under Brazilian test conditions (i.e. diametrical loading of cylindrical discs) for one particular layered sandstone which is from Modave in the south of Belgium. The variations of the strength in combination with the failure patterns are examined as a function of the inclination angle between the layer plane and the loading direction. The experimental, results clearly show that the induced fracture patterns are a combination of tensile and/or shear fractures. In shape effect experiments the layer thickness and the number of layer boundaries are investigated. Different blocks of Modave sandstone are used to prepare samples. The layer thickness is different among the various blocks, but the layer thickness in each studied rock block can be considered to be constant;hence, the number of layer boundaries changes according to the sample diameter for samples of the same block. The experimental study shows that the layer thickness plays a more important role than the number of layer boundaries per sample.

  18. One-Block CYRCA: an automated procedure for identifying multiple-block alignments from single block queries

    OpenAIRE

    Frenkel-Morgenstern, Milana; Singer, Alice; Bronfeld, Hagit; Pietrokovski, Shmuel

    2005-01-01

    One-Block CYRCA is an automated procedure for identifying multiple-block alignments from single block queries (). It is based on the LAMA and CYRCA block-to-block alignment methods. The procedure identifies whether the query blocks can form new multiple-block alignments (block sets) with blocks from a database or join pre-existing database block sets. Using pre-computed LAMA block alignments and CYRCA sets from the Blocks database reduces the computation time. LAMA and CYRCA are highly sensit...

  19. The wild tapered block bootstrap

    DEFF Research Database (Denmark)

    Hounyo, Ulrich

    In this paper, a new resampling procedure, called the wild tapered block bootstrap, is introduced as a means of calculating standard errors of estimators and constructing confidence regions for parameters based on dependent heterogeneous data. The method consists in tapering each overlapping block...... of the series first, the applying the standard wild bootstrap for independent and heteroscedastic distrbuted observations to overlapping tapered blocks in an appropriate way. Its perserves the favorable bias and mean squared error properties of the tapered block bootstrap, which is the state-of-the-art block......-order asymptotic validity of the tapered block bootstrap as well as the wild tapered block bootstrap approximation to the actual distribution of the sample mean is also established when data are assumed to satisfy a near epoch dependent condition. The consistency of the bootstrap variance estimator for the sample...

  20. Block Voter Model

    CERN Document Server

    Sampaio, C I N

    2011-01-01

    We introduce and study the block voter model with noise on two-dimensional square lattices using Monte Carlo simulations and finite-size scaling techniques. The model is defined by an outflow dynamics where a central set of $N_{PCS}$ spins, here denoted by persuasive cluster spins (PCS), tries to influence the opinion of their neighbouring counterparts. We consider the collective behaviour of the entire system with varying PCS size. When $N_{PCS}>2$, the system exhibits an order-disorder phase transition at a critical noise parameter $q_{c}$ which is a monotonically increasing function of the size of the persuasive cluster. We conclude that how large the PCS is more power of persuasion it has. It also seems that the resulting critical behaviour is Ising-like independent of the range of the interactions.

  1. Spintronics: Conceptual Building Blocks

    Science.gov (United States)

    Ansermet, J.-Ph.

    The purpose of this introduction to spintronics is to provide some elementary description of its conceptual building blocks. Thus, it is intended for a newcomer to the field. After recalling rudimentary descriptions of spin precession and spin relaxation, spin-dependent transport is treated within the Boltzmann formalism. This suffices to introduce key notions such as the spin asymmetry of the conductivities in the two-current model, the spin diffusion length, and spin accumulation. Two basic mechanisms of spin relaxation are then presented, one arising from spin-orbit scattering and the other from electron-magnon collisions. Finally, the action of a spin-polarized current on magnetization is presented in a thermodynamics framework. This introduces the notion of spin torque and the characteristic length scale over which the transverse spin polarization of conduction electron decays as it is injected into a magnet.

  2. Photovoltaic building blocks

    DEFF Research Database (Denmark)

    Hanberg, Peter Jesper; Jørgensen, Anders Michael

    2014-01-01

    it directcompetitive with fossil energy sources a further reduction is needed. By increasing the efficiency of the solar cells one gain an advantage through the whole chain of cost. So that per produced Watt of power less material is spent, installation costs are lower, less area is used etc. With an average...... efficiency of about 15% for commercial Silicon solar cells there is still much to gain. DTU Danchip provides research facilities, equipment and expertise for the building blocks that comprises fabricating the efficient solar cell. In order to get more of the sun light into the device we provide thin film......Photovoltaics (PV), better known as solar cells, are now a common day sight on many rooftops in Denmark.The installed capacity of PV systems worldwide is growing exponentially1 and is the third most importantrenewable energy source today. The cost of PV is decreasing fast with ~10%/year but to make...

  3. Atomic Basic Blocks

    Science.gov (United States)

    Scheler, Fabian; Mitzlaff, Martin; Schröder-Preikschat, Wolfgang

    Die Entscheidung, einen zeit- bzw. ereignisgesteuerten Ansatz für ein Echtzeitsystem zu verwenden, ist schwierig und sehr weitreichend. Weitreichend vor allem deshalb, weil diese beiden Ansätze mit äußerst unterschiedlichen Kontrollflussabstraktionen verknüpft sind, die eine spätere Migration zum anderen Paradigma sehr schwer oder gar unmöglich machen. Wir schlagen daher die Verwendung einer Zwischendarstellung vor, die unabhängig von der jeweils verwendeten Kontrollflussabstraktion ist. Für diesen Zweck verwenden wir auf Basisblöcken basierende Atomic Basic Blocks (ABB) und bauen darauf ein Werkzeug, den Real-Time Systems Compiler (RTSC) auf, der die Migration zwischen zeit- und ereignisgesteuerten Systemen unterstützt.

  4. The Block-block Bootstrap: Improved Asymptotic Refinements

    OpenAIRE

    Donald W.K. Andrews

    2002-01-01

    The asymptotic refinements attributable to the block bootstrap for time series are not as large as those of the nonparametric iid bootstrap or the parametric bootstrap. One reason is that the independence between the blocks in the block bootstrap sample does not mimic the dependence structure of the original sample. This is the join-point problem. In this paper, we propose a method of solving this problem. The idea is not to alter the block bootstrap. Instead, we alter the original sample sta...

  5. Convergence rates of empirical block length selectors for block bootstrap

    OpenAIRE

    Nordman, Daniel J.; Lahiri, Soumendra N.

    2014-01-01

    We investigate the accuracy of two general non-parametric methods for estimating optimal block lengths for block bootstraps with time series – the first proposed in the seminal paper of Hall, Horowitz and Jing (Biometrika 82 (1995) 561–574) and the second from Lahiri et al. (Stat. Methodol. 4 (2007) 292–321). The relative performances of these general methods have been unknown and, to provide a comparison, we focus on rates of convergence for these block length selectors for the moving block ...

  6. The Dependence of Physical Mechanical Properties of Concrete Pavement Blocks on Coarse Aggregate Type

    Directory of Open Access Journals (Sweden)

    Malaiškienė Jurgita

    2014-12-01

    Full Text Available The aim of this research is to determine the dependences of the physical mechanical properties of vibropressed concrete (pavement blocks on the type of coarse aggregate used in the main layer. Sustainability of concrete pavement blocks is a really important matter. Five different batches of pavement blocks were produced, changing the consistence ratio of coarse aggregate in the main layer. There are two types of course aggregate: crushed gravel and granite. The consistence of a facing layer was not changed. All tests: density, tensile split strength, water absorption for vibro-pressed concrete units were made according to EN 1338:2003+AC2006.

  7. Large Block Test Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W

    2001-12-01

    This report documents the Large-Block Test (LBT) conducted at Fran Ridge near Yucca Mountain, Nevada. The LBT was a thermal test conducted on an exposed block of middle non-lithophysal Topopah Spring tuff (Tptpmn) and was designed to assist in understanding the thermal-hydrological-mechanical-chemical (THMC) processes associated with heating and then cooling a partially saturated fractured rock mass. The LBT was unique in that it was a large (3 x 3 x 4.5 m) block with top and sides exposed. Because the block was exposed at the surface, boundary conditions on five of the six sides of the block were relatively well known and controlled, making this test both easier to model and easier to monitor. This report presents a detailed description of the test as well as analyses of the data and conclusions drawn from the test. The rock block that was tested during the LBT was exposed by excavation and removal of the surrounding rock. The block was characterized and instrumented, and the sides were sealed and insulated to inhibit moisture and heat loss. Temperature on the top of the block was also controlled. The block was heated for 13 months, during which time temperature, moisture distribution, and deformation were monitored. After the test was completed and the block cooled down, a series of boreholes were drilled, and one of the heater holes was over-cored to collect samples for post-test characterization of mineralogy and mechanical properties. Section 2 provides background on the test. Section 3 lists the test objectives and describes the block site, the site configuration, and measurements made during the test. Section 3 also presents a chronology of events associated with the LBT, characterization of the block, and the pre-heat analyses of the test. Section 4 describes the fracture network contained in the block. Section 5 describes the heating/cooling system used to control the temperature in the block and presents the thermal history of the block during the test

  8. Covariant Approaches to Superconformal Blocks

    CERN Document Server

    Fitzpatrick, A Liam; Khandker, Zuhair U; Li, Daliang; Poland, David; Simmons-Duffin, David

    2014-01-01

    We develop techniques for computing superconformal blocks in 4d superconformal field theories. First we study the super-Casimir differential equation, deriving simple new expressions for superconformal blocks for 4-point functions containing chiral operators in theories with N-extended supersymmetry. We also reproduce these results by extending the "shadow formalism" of Ferrara, Gatto, Grillo, and Parisi to supersymmetric theories, where superconformal blocks can be represented as superspace integrals of three-point functions multiplied by shadow three-point functions.

  9. Dimensional Reduction for Conformal Blocks

    CERN Document Server

    Hogervorst, Matthijs

    2016-01-01

    We consider the dimensional reduction of a CFT, breaking multiplets of the d-dimensional conformal group SO(d+1,1) up into multiplets of SO(d,1). This leads to an expansion of d-dimensional conformal blocks in terms of blocks in d-1 dimensions. In particular, we obtain a formula for 3d conformal blocks as an infinite sum over 2F1 hypergeometric functions with closed-form coefficients.

  10. Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength

    DEFF Research Database (Denmark)

    Jæger, Pia Therese; Nielsen, Zbigniew Jerzy Koscielniak; Henningsen, Lene Marianne;

    2013-01-01

    : The authors hypothesized that the adductor canal block (ACB), a predominant sensory blockade, reduces quadriceps strength compared with placebo (primary endpoint, area under the curve, 0.5-6 h), but less than the femoral nerve block (FNB; secondary endpoint). Other secondary endpoints were...

  11. New adhesive systems based on functionalized block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Kent, M.; Saunders, R.; Hurst, M.; Small, J.; Emerson, J.; Zamora, D.

    1997-05-01

    The goal of this work was to evaluate chemically-functionalized block copolymers as adhesion promoters for metal/thermoset resin interfaces. Novel block copolymers were synthesized which contain pendant functional groups reactive toward copper and epoxy resins. In particular, imidazole and triazole functionalities that chelate with copper were incorporated onto one block, while secondary amines were incorporated onto the second block. These copolymers were found to self-assemble from solution onto copper surfaces to form monolayers. The structure of the adsorbed monolayers were studied in detail by neutron reflection and time-of-flight secondary ion mass spectrometry. The monolayer structure was found to vary markedly with the solution conditions and adsorption protocol. Appropriate conditions were found for which the two blocks form separate layers on the surface with the amine functionalized block exposed at the air surface. Adhesion testing of block copolymer-coated copper with epoxy resins was performed in both lap shear and peel modes. Modest enhancements in bond strengths were observed with the block copolymer applied to the native oxide. However, it was discovered that the native oxide is the weak link, and that by simply removing the native oxide, and then applying an epoxy resin before the native oxide can reform, excellent bond strength in the as-prepared state as well as excellent retention of bond strength after exposure to solder in ambient conditions are obtained. It is recommended that long term aging studies be performed with and without the block copolymer. In addition, the functionalized block copolymer method should be evaluated for another system that has inherently poor bonding, such as the nickel/silicone interface, and for systems involving metals and alloys which form oxides very rapidly, such as aluminum and stainless steel, where bonding strategies involve stabilizing the native oxide.

  12. Multi-block and path modelling procedures

    DEFF Research Database (Denmark)

    Høskuldsson, Agnar

    2008-01-01

    The author has developed a unified theory of path and multi-block modelling of data. The data blocks are arranged in a directional path. Each data block can lead to one or more data blocks. It is assumed that there is given a collection of input data blocks. Each of them is supposed to describe one...... or more intermediate data blocks. The output data blocks are those that are at the ends of the paths and have no succeeding data blocks. The optimisation procedure finds weights for the input data blocks so that the size of the total loadings for the output data blocks are maximised. When the optimal...... weight vectors have been determined, the score and loading vectors for the data blocks in the path are determined. Appropriate adjustment of the data blocks is carried out at each step. Regression coefficients are computed for each data block that show how the data block is estimated by data blocks...

  13. OPAL Various Lead Glass Blocks

    CERN Multimedia

    These lead glass blocks were part of a CERN detector called OPAL (one of the four experiments at the LEP particle detector). OPAL uses some 12 000 blocks of glass like this to measure particle energies in the electromagnetic calorimeter. This detector measured the energy deposited when electrons and photons were slowed down and stopped.

  14. Classical Virasoro irregular conformal block

    CERN Document Server

    Rim, Chaiho

    2015-01-01

    Virasoro irregular conformal block with arbitrary rank is obtained for the classical limit or equivalently Nekrasov-Shatashvili limit using the beta-deformed irregular matrix model (Penner-type matrix model for the irregular conformal block). The same result is derived using the generalized Mathieu equation which is equivalent to the loop equation of the irregular matrix model.

  15. The Shamrock lumbar plexus block

    DEFF Research Database (Denmark)

    Sauter, Axel R; Ullensvang, Kyrre; Niemi, Geir;

    2015-01-01

    BACKGROUND: The Shamrock technique is a new method for ultrasound-guided lumbar plexus blockade. Data on the optimal local anaesthetic dose are not available. OBJECTIVE: The objective of this study is to estimate the effective dose of ropivacaine 0.5% for a Shamrock lumbar plexus block. DESIGN: A...... prospective dose-finding study using Dixon's up-and-down sequential method. SETTING: University Hospital Orthopaedic Anaesthesia Unit. INTERVENTION: Shamrock lumbar plexus block performance and block assessment were scheduled preoperatively. Ropivacaine 0.5% was titrated with the Dixon and Massey up......-and-down method using a stepwise change of 5 ml in each consecutive patient. Combined blocks of the femoral, the lateral femoral cutaneous and the obturator nerve were prerequisite for a successful lumbar plexus block. PATIENTS: Thirty patients scheduled for lower limb orthopaedic surgery completed the study...

  16. An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to fabricate a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate a suitably-doped active layer...

  17. Tailoring Phase Behavior and Mechanical Properties in Thermoplastic Elastomers through Block Sequence and Macromolecular Architecture

    Science.gov (United States)

    Burns, Adam; Register, Richard

    2015-03-01

    Block copolymers exhibit unique properties which depend not only on the identities of the constituent blocks but also the block sequence and macromolecular architecture. Thermoplastic elastomers (TPEs) are a prime example. In TPEs the arrangement of glassy end blocks flanking a long rubbery midblock gives rise to a physically cross-linked, elastic solid. Exchanging the glassy blocks for crystalline blocks can improve the processability and solvent resistance, but adversely affects the mechanical performance. The block sequence crystalline-glassy-rubbery-glassy-crystalline has been developed to combine the advantages of both crystalline and glassy blocks. Careful selection of block lengths produces materials in which the order-disorder transition temperature lies below the melting point of the crystalline block, ensuring that the melt will be homogeneous above the melting point. Access to single-phase melts provides a large reduction in viscosity and elasticity over conventional TPEs, which remain microphase-separated in the melt. Inserting the glassy blocks between the crystalline and rubbery blocks produces a vitreous layer surrounding the crystalline domains, which improves the room-temperature mechanical performance. Incorporating the crystalline-glassy-rubbery motif into the arms of star block copolymers adds another level of control. The star architecture introduces a permanent cross-link at the center of the star without appreciably affecting the phase behavior.

  18. Structure of adsorption layers of amphiphilic copolymers on inorganic or organic particle surfaces

    OpenAIRE

    Bulychev, Nikolay; Dervaux, Bart; Dimberger, Klaus; Zubov, Vitali; Du Prez, Filip; Eisenbach, Claus D

    2010-01-01

    The structure of adsorption layers of amphiphilic block and block-like copolymers of poly(isobornyl acrylate) and poly(acrylic acid) on the surface of hydrophilic titanium dioxide and hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous studied by the electrokinetic sonic amplitude (ESA) method. The electroacoustic behaviour of the polyelectrolyte block copolymer-coated particles could be described in the context of the polymer gel layer theory. The polymer layer around the particl...

  19. Preheating to around 100°C under endcap blocks before welding at KHI.

    CERN Multimedia

    Loveless, D

    2000-01-01

    The 600mm thick sector blocks of the CMS endcaps are made from three layers of 200mm plates welded together. During the manufacture at KHI, the blocks are preheated to around 100°C to prevent cracks in the welds.

  20. Block Curricula: A Guide to Teaching with Unit Blocks and Hollow Blocks in the Classroom.

    Science.gov (United States)

    Clark, Phyllis; Tiedemann, Nancy

    This curriculum guide for preschool teachers was designed for use with wooden unit and hollow blocks to foster a variety of math, science, language, and social skills. Following an introduction to the curriculum and a discussion of cooperative learning and stages of block building, the guide is divided into three parts. Part 1 of the guide, "Unit…

  1. Criminal Justice Systems. Block I: Law Enforcement. Block II: The Courts. Block III: Corrections. Block IV: Community Relations. Block V: Proficiency Skills. Block VI: Criminalistics. Student Guide.

    Science.gov (United States)

    Florida State Dept. of Education, Tallahassee. Div. of Vocational, Adult, and Community Education.

    This student guide together with an instructor guide comprise a set of curriculum materials on the criminal justice system. The student guide contains self-contained instructional material that students can study at their own pace most of the time. Six major subject areas or blocks, which are further broken down into several units, with some units…

  2. Criminal Justice Systems. Block I: Law Enforcement. Block II: The Courts. Block III: Corrections. Block IV: Community Relations. Block V: Proficiency Skills. Block VI: Criminalistics. Instructor Guide.

    Science.gov (United States)

    Florida State Dept. of Education, Tallahassee. Div. of Vocational, Adult, and Community Education.

    This instructor guide together with a student guide comprise a set of curriculum materials on the criminal justice system. The instructor guide is a resource for planning and managing individualized, competency-based instruction in six major subject areas or blocks, which are further broken down into several units with some units having several…

  3. Two Layer Vector Quantization of Images

    Directory of Open Access Journals (Sweden)

    V. Michalcin

    2001-06-01

    Full Text Available This paper deals with spatial scaleable vector quantization ofimages by using two layers. At the base layer the small dimensionalfull search vector quantization of an image of block means is carriedout. After subtracting it from the input image at the enhancement layerthe difference of full spatial resolution is quantized by largedimensional weighted pyramid vector quantizer in transform domain.Experimental results demonstrate acceptable quality of the downscaledimage from the output of base layer at very low bit rate andpossibility of next increasing its quality by the upscaled differenceimage from the output of enhancement layer.

  4. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

    Science.gov (United States)

    Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D

    2014-11-25

    Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins.

  5. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

    Science.gov (United States)

    Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D

    2014-11-25

    Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins. PMID:25393374

  6. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  7. Block copolymer patterns and templates

    Directory of Open Access Journals (Sweden)

    Mingqi Li

    2006-09-01

    Full Text Available This review describes the chemical and physical aspects of patternable block copolymers and their use for nanostructure fabrication. The patternability of block copolymers results from their ability to self-assemble into microdomains and the manipulation of these patterns by a variety of physical and chemical means. Procedures for achieving long-range lateral order, as well as orientation order of microdomain patterns, are discussed. The level of control that these strategies afford has enabled block copolymers to be used as templates for fabricating a variety of nanostructures.

  8. Does obturator nerve block always occur in 3-1 block?

    Directory of Open Access Journals (Sweden)

    İbrahim Tekdemir

    2011-06-01

    Full Text Available In the femoral “3-in-1 block”, obturator nerve block is routinely unsuccessful. Anatomical studies are not available to explain why blockade of obturator nerve or lumbar plexus does not occur. The aim of this study was to examine the effectiveness of femoral “3-in-1 block” obturator nerve block on a cadaver model.Materials and methods: Totally, 12 mature adult human cadavers were selected. Methylene blue dye (30 ml was injected under the fascia iliaca in eight cadavers and into the femoral nerve sheath in four cadavers. Careful bilateral dissections were performed following dye injections.Results: It was seen that the dye did not spread to the medial part of the psoas major muscle and the obturator nerve was not stained with the dye in eight cadavers in whom dye was injected laterally into the femoral sheat. In four cadavers in whom dye was injected into the femoral nerve sheat, metylene blue spread through fascial layers in the plane under the psoas muscle and stained the obturator nerve just before emerging medially from the fascia psoas. At this point, the obturator nerve pierced the psoas fascia and extended extrafascially in the medial and deep borders of the psoas muscle. In this area, the upper section of the obturator nerve was found also to be stained with the dye.Conclusion: We concluded that the cause of an unsuccessful obturator nerve block might be the fascial anatomy of this region. The lateral cutaneous femoral nerve and the femoral nerve easily can be blocked in the fascia iliaca compartment, but the obturator nerve block fails because of its being extrafascial in this region. J Clin Exp Invest 2011;2(2:149-51

  9. Recursion Relations for Conformal Blocks

    CERN Document Server

    Penedones, João; Yamazaki, Masahito

    2015-01-01

    In the context of conformal field theories in general space-time dimension, we find all the possible singularities of the conformal blocks as functions of the scaling dimension $\\Delta$ of the exchanged operator. In particular, we argue, using representation theory of parabolic Verma modules, that in odd spacetime dimension the singularities are only simple poles. We discuss how to use this information to write recursion relations that determine the conformal blocks. We first recover the recursion relation introduced in 1307.6856 for conformal blocks of external scalar operators. We then generalize this recursion relation for the conformal blocks associated to the four point function of three scalar and one vector operator. Finally we specialize to the case in which the vector operator is a conserved current.

  10. MarineMineralsProgramBlocks

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains OCS block outlines and delineated polygons in ESRI ArcGIS shape file format for the BOEM Gulf of Mexico Region that contain sediment...

  11. Left bundle-branch block

    DEFF Research Database (Denmark)

    Risum, Niels; Strauss, David; Sogaard, Peter;

    2013-01-01

    The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently...

  12. A Novel Tetrathiafulvalene Building Block

    DEFF Research Database (Denmark)

    Jeppesen, Jan Oskar; Takimiya, Kazuo; Thorup, Niels;

    1999-01-01

    Efficient synthesis of a novel tetrathiafulvalene building block. 2,3-bis(2-cyanoethylthio)-6,7-bis(thiocyanato-methyl)tetrathiafulv alene (7) useful for stepwise and asymmetrical bis-function-alization is reported.......Efficient synthesis of a novel tetrathiafulvalene building block. 2,3-bis(2-cyanoethylthio)-6,7-bis(thiocyanato-methyl)tetrathiafulv alene (7) useful for stepwise and asymmetrical bis-function-alization is reported....

  13. Statistical cryptanalysis of block ciphers

    OpenAIRE

    Junod, Pascal; Vaudenay, Serge

    2007-01-01

    Since the development of cryptology in the industrial and academic worlds in the seventies, public knowledge and expertise have grown in a tremendous way, notably because of the increasing, nowadays almost ubiquitous, presence of electronic communication means in our lives. Block ciphers are inevitable building blocks of the security of various electronic systems. Recently, many advances have been published in the field of public-key cryptography, being in the understanding of involved securi...

  14. NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Guojun Liu

    2000-01-01

    Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, selfassembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films with nanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisopreneblock-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass fraction of 20% relative to the triblock or the total PtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrix of PCEMA and PI. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannels were formed by extracting out hPtBA with solvent. Alternatively, larger channels were obtained from extracting out hPtBA and hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeability constants ~6 orders of magnitude higher than that of low-density polyethylene films.

  15. Hydrogen-bonded multilayers of micelles of a dually responsive dicationic block copolymer

    OpenAIRE

    Erel, İrem; Karahan, H. Enis; Demirel, A. Levent; Tuncer, Cansel; Bütün, Vural

    2012-01-01

    We report the fabrication of hydrogen-bonded multilayers of micelles of a dually responsive, dicationic block copolymer, poly[2-(N-morpholino)ethyl methacrylate-block-2-(diisopropylamino)ethyl methacrylate] (PMEMA-b-PDPA). By taking advantage of the difference in the hydrophilicity of PMEMA and PDPA blocks, micelles with a PMEMA-corona and a PDPA-core were obtained above pH 6.5 and were assembled layer-by-layer at the surface with tannic acid (TA) at pH 7.4 through hydrogen bonding interactio...

  16. Fibrinogen adsorption on blocked surface of albumin

    DEFF Research Database (Denmark)

    Holmberg, Maria; Hou, Xiaolin

    2011-01-01

    We have investigated the adsorption of albumin and fibrinogen onto PET (polyethylene terephthalate) and glass surfaces and how pre-adsorption of albumin onto these surfaces can affect the adsorption of later added fibrinogen. For materials and devices being exposed to blood, adsorption...... of fibrinogen is often a non-wanted event, since fibrinogen is part of the clotting cascade and unspecific adsorption of fibrinogen can have an influence on the activation of platelets. Albumin is often used as blocking agent for avoiding unspecific protein adsorption onto surfaces in devices designed to handle...... energies, the adsorption of both albumin and fibrinogen has been monitored simultaneously on the same sample. Information about topography and coverage of adsorbed protein layers has been obtained using AFM (Atomic Force Microscopy) analysis in liquid. Our studies show that albumin adsorbs in a multilayer...

  17. Functional polymers as nanoscopic building blocks

    International Nuclear Information System (INIS)

    Polyphenylene dendrimers are introduced as polymeric building blocks--with a strictly monodisperse particle size distribution within the nanometer range--for the construction of nanostructured materials and devices. The possibility for the introduction of different functionalities in the core, the scaffold or the periphery of the dendrimers offer their use as interesting modules for photonic, electronic or bioactive structures and supramolecular functional assemblies. Thus, dendrimers complement the available set of nanoscopic building blocks made from metals, e.g., Au nanoclusters and semiconductors, e.g., luminescent quantum dots. In a first set of experiments, we describe the fabrication of multilayer architectures using dendrimers with chargeable groups at the surface. This way, the polyelectrolyte deposition technique can be applied for the construction of hybrid layered assemblies with a control of the internal supramolecular structure at the nanometer level. Surface plasmon field-enhanced fluorescence spectroscopy is used to monitor the luminescent properties of dendrimers with a phthalocyanine core integrated into such a multilayer assembly. AFM and SEM micrographs demonstrate the use of surface-functionalized dendrimers (exposing sulfur groups at the periphery) in combination with Au nanoparticles for the controlled assembly of hybrid aggregates as nanoscopic functional devices

  18. QuaBingo: A Prediction System for Protein Quaternary Structure Attributes Using Block Composition

    Science.gov (United States)

    Tung, Chi-Hua; Chen, Chi-Wei; Guo, Ren-Chao; Ng, Hui-Fuang

    2016-01-01

    Background. Quaternary structures of proteins are closely relevant to gene regulation, signal transduction, and many other biological functions of proteins. In the current study, a new method based on protein-conserved motif composition in block format for feature extraction is proposed, which is termed block composition. Results. The protein quaternary assembly states prediction system which combines blocks with functional domain composition, called QuaBingo, is constructed by three layers of classifiers that can categorize quaternary structural attributes of monomer, homooligomer, and heterooligomer. The building of the first layer classifier uses support vector machines (SVM) based on blocks and functional domains of proteins, and the second layer SVM was utilized to process the outputs of the first layer. Finally, the result is determined by the Random Forest of the third layer. We compared the effectiveness of the combination of block composition, functional domain composition, and pseudoamino acid composition of the model. In the 11 kinds of functional protein families, QuaBingo is 23% of Matthews Correlation Coefficient (MCC) higher than the existing prediction system. The results also revealed the biological characterization of the top five block compositions. Conclusions. QuaBingo provides better predictive ability for predicting the quaternary structural attributes of proteins.

  19. QuaBingo: A Prediction System for Protein Quaternary Structure Attributes Using Block Composition

    Directory of Open Access Journals (Sweden)

    Chi-Hua Tung

    2016-01-01

    Full Text Available Background. Quaternary structures of proteins are closely relevant to gene regulation, signal transduction, and many other biological functions of proteins. In the current study, a new method based on protein-conserved motif composition in block format for feature extraction is proposed, which is termed block composition. Results. The protein quaternary assembly states prediction system which combines blocks with functional domain composition, called QuaBingo, is constructed by three layers of classifiers that can categorize quaternary structural attributes of monomer, homooligomer, and heterooligomer. The building of the first layer classifier uses support vector machines (SVM based on blocks and functional domains of proteins, and the second layer SVM was utilized to process the outputs of the first layer. Finally, the result is determined by the Random Forest of the third layer. We compared the effectiveness of the combination of block composition, functional domain composition, and pseudoamino acid composition of the model. In the 11 kinds of functional protein families, QuaBingo is 23% of Matthews Correlation Coefficient (MCC higher than the existing prediction system. The results also revealed the biological characterization of the top five block compositions. Conclusions. QuaBingo provides better predictive ability for predicting the quaternary structural attributes of proteins.

  20. QuaBingo: A Prediction System for Protein Quaternary Structure Attributes Using Block Composition.

    Science.gov (United States)

    Tung, Chi-Hua; Chen, Chi-Wei; Guo, Ren-Chao; Ng, Hui-Fuang; Chu, Yen-Wei

    2016-01-01

    Background. Quaternary structures of proteins are closely relevant to gene regulation, signal transduction, and many other biological functions of proteins. In the current study, a new method based on protein-conserved motif composition in block format for feature extraction is proposed, which is termed block composition. Results. The protein quaternary assembly states prediction system which combines blocks with functional domain composition, called QuaBingo, is constructed by three layers of classifiers that can categorize quaternary structural attributes of monomer, homooligomer, and heterooligomer. The building of the first layer classifier uses support vector machines (SVM) based on blocks and functional domains of proteins, and the second layer SVM was utilized to process the outputs of the first layer. Finally, the result is determined by the Random Forest of the third layer. We compared the effectiveness of the combination of block composition, functional domain composition, and pseudoamino acid composition of the model. In the 11 kinds of functional protein families, QuaBingo is 23% of Matthews Correlation Coefficient (MCC) higher than the existing prediction system. The results also revealed the biological characterization of the top five block compositions. Conclusions. QuaBingo provides better predictive ability for predicting the quaternary structural attributes of proteins. PMID:27610389

  1. Planar varactor frequency multiplier devices with blocking barrier

    Science.gov (United States)

    Lieneweg, Udo (Inventor); Frerking, Margaret A. (Inventor); Maserjian, Joseph (Inventor)

    1994-01-01

    The invention relates to planar varactor frequency multiplier devices with a heterojunction blocking barrier for near millimeter wave radiation of moderate power from a fundamental input wave. The space charge limitation of the submillimeter frequency multiplier devices of the BIN(sup +) type is overcome by a diode structure comprising an n(sup +) doped layer of semiconductor material functioning as a low resistance back contact, a layer of semiconductor material with n-type doping functioning as a drift region grown on the back contact layer, a delta doping sheet forming a positive charge at the interface of the drift region layer with a barrier layer, and a surface metal contact. The layers thus formed on an n(sup +) doped layer may be divided into two isolated back-to-back BNN(sup +) diodes by separately depositing two surface metal contacts. By repeating the sequence of the drift region layer and the barrier layer with the delta doping sheet at the interfaces between the drift and barrier layers, a plurality of stacked diodes is formed. The novelty of the invention resides in providing n-type semiconductor material for the drift region in a GaAs/AlGaAs structure, and in stacking a plurality of such BNN(sup +) diodes stacked for greater output power with and connected back-to-back with the n(sup +) GaAs layer as an internal back contact and separate metal contact over an AlGaAs barrier layer on top of each stack.

  2. Wafer-Scale Nanopillars Derived from Block Copolymer Lithography for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Li, Tao; Wu, Kaiyu; Rindzevicius, Tomas;

    2016-01-01

    ). Direct silicon etching with high aspect ratio templated by the block copolymer mask is realized without any intermediate layer or external precursors. Uniquely, an atomic layer deposition (ALD)-assisted method is introduced to allow reversing of the morphology relative to the initial pattern. As a result...

  3. Block Matching for Object Tracking

    Energy Technology Data Exchange (ETDEWEB)

    Gyaourova, A; Kamath, C; Cheung, S

    2003-10-13

    Models which describe road traffic patterns can be helpful in detection and/or prevention of uncommon and dangerous situations. Such models can be built by the use of motion detection algorithms applied to video data. Block matching is a standard technique for encoding motion in video compression algorithms. We explored the capabilities of the block matching algorithm when applied for object tracking. The goal of our experiments is two-fold: (1) to explore the abilities of the block matching algorithm on low resolution and low frame rate video and (2) to improve the motion detection performance by the use of different search techniques during the process of block matching. Our experiments showed that the block matching algorithm yields good object tracking results and can be used with high success on low resolution and low frame rate video data. We observed that different searching methods have small effect on the final results. In addition, we proposed a technique based on frame history, which successfully overcame false motion caused by small camera movements.

  4. Climatological features of blocking anticyclones

    International Nuclear Information System (INIS)

    Several climatological studies have been previously performed using large observational data sets (i.e., 10 years or longer) in order to determine the predominant characteristics of blocking anticyclones, including favored development regions, duration, preferred seasonal occurrence, and frequency of occurrence. These studies have shown that blocking anticyclones occur most frequently from October to April over the eastern Atlantic and Pacific oceans downstream from both the North American and Asian continental regions and the storm track regions to the east of these continents. Some studies have also revealed the presence of a third region block formation in western Russia near 40 degrees E which is associated with another storm track region over the Mediterranean and western Asia

  5. Projectors, Shadows, and Conformal Blocks

    CERN Document Server

    Simmons-Duffin, David

    2012-01-01

    We introduce a method for computing conformal blocks of operators in arbitrary Lorentz representations in any spacetime dimension, making it possible to apply bootstrap techniques to operators with spin. The key idea is to implement the "shadow formalism" of Ferrara, Gatto, Grillo, and Parisi in a setting where conformal invariance is manifest. Conformal blocks in d-dimensions can be expressed as integrals over the projective null-cone in the "embedding space" R^{d+1,1}. Taking care with their analytic structure, these integrals can be evaluated in great generality, reducing the computation of conformal blocks to a bookkeeping exercise. To facilitate calculations in four-dimensional CFTs, we introduce techniques for writing down conformally-invariant correlators using auxiliary twistor variables, and demonstrate their use in some simple examples.

  6. Transient instability upon temperature quench in weakly ordered block copolymers

    OpenAIRE

    Qi, Shuyan; Wang, Zhen-Gang

    1999-01-01

    We report a novel transient instability upon temperature quench in weakly ordered block copolymer microphases possessing a soft direction or directions, such as the lamellar and hexagonal cylinder (HEX) phases. We show that reequilibration of the order parameter is accompanied by transient long wavelength undulation of the layers or cylinders—with an initial wavelength that depends on the depth of the temperature quench—that eventually disappears as the structure reaches its equilibrium at th...

  7. Block ground interaction of rockfalls

    Science.gov (United States)

    Volkwein, Axel; Gerber, Werner; Kummer, Peter

    2016-04-01

    During a rockfall the interaction of the falling block with the ground is one of the most important factors that define the evolution of a rockfall trajectory. It steers the rebound, the rotational movement, possibly brake effects, friction losses and damping effects. Therefore, if most reliable rockfall /trajectory simulation software is sought a good understanding of the block ground interaction is necessary. Today's rockfall codes enable the simulation of a fully 3D modelled block within a full 3D surface . However, the details during the contact, i.e. the contact duration, the penetration depth or the dimension of the marks in the ground are usually not part of the simulation. Recent field tests with rocks between 20 and 80 kg have been conducted on a grassy slope in 2014 [1]. A special rockfall sensor [2] within the blocks measured the rotational velocity and the acting accelerations during the tests. External video records and a so-called LocalPositioningSystem deliver information on the travel velocity. With these data not only the flight phases of the trajectories but also the contacts with the ground can be analysed. During the single jumps of a block the flight time, jump length, the velocity, and the rotation are known. During the single impacts their duration and the acting accelerations are visible. Further, the changes of rotational and translational velocity influence the next jump of the block. The change of the rotational velocity over the whole trajectory nicely visualizes the different phases of a rockfall regarding general acceleration and deceleration in respect to the inclination and the topography of the field. References: [1] Volkwein A, Krummenacher B, Gerber W, Lardon J, Gees F, Brügger L, Ott T (2015) Repeated controlled rockfall trajectory testing. [Abstract] Geophys. Res. Abstr. 17: EGU2015-9779. [2] Volkwein A, Klette J (2014) Semi-Automatic Determination of Rockfall Trajectories. Sensors 14: 18187-18210.

  8. OPAL 96 Blocks Lead Glass

    CERN Multimedia

    This array of 96 lead glass bricks formed part of the OPAL electromagnetic calorimeter. One half of the complete calorimeter is shown in the picture above. There were 9440 lead glass counters in the OPAL electromagnetic calorimeter. These are made of Schott type SF57 glass and each block weighs about 25 kg and consists of 76% PbO by weight. Each block has a Hamamatsu R2238 photomultiplier glued on to it. The complete detector was in the form of a cylinder 7m long and 6m in diameter. It was used to measure the energy of electrons and photons produced in LEP interactions.

  9. Planning Block Play Experiences for Young Children.

    Science.gov (United States)

    Baker, Betty Ruth

    Playing with blocks can facilitate the creative, social, emotional, physical, and cognitive development of young children. This article presents information and activities concerning block play and its role in young children's experience. Topics covered include: (1) types of blocks; (2) selection of blocks and accessories; (3) planning of the…

  10. The New Block Cipher Design (Tigris Cipher

    Directory of Open Access Journals (Sweden)

    Omar A. Dawood

    2015-11-01

    Full Text Available In the present paper we have proposed a new variant of AES cipher with high level of security and an elegant construction called TIGRIS cipher. The TIGRIS name has been derived from one of the two famous rivers in Iraq. The proposed TIGRIS cipher is a revision for the proposed Euphrates cipher which has already been published. It has been designed with a good coherent structure that is based on solid algebraic and well mathematical opinions. The proposed cipher uses the SPN structure and what is known by the Galois Field GF (28. It is an iterated cipher that has a conservative design which is easily implemented on both hardware and software. It operates with block size of 128-bits and with three variable key lengths of 128-bits, 192-bits and 256-bits in addition to sixteen rounds or multiples of four rounds. The proposed cipher works with good invertible operations' stages and a compact duplicated ciphering key. The Tigris cipher construction strategy includes the adoption of construction a new S-box with high non-linearity that uses the same routines of the AES-S-box stage but with different modular arithmetic of irreducible polynomial and different affine matrix in addition to the distinct constant vector. The second and the third layers of the proposed model are based on the shifting concept for the confusion and diffusion process with reversible operations. The last layer of the proposed model is the key addition layer that is responsible for the expanding and generating the ciphering key by two directions those of row and column expansion, which are associated with two constant vectors of golden ratio and base nature algorithm as a fixed word to eliminate any weak or semi-weak ciphering key.

  11. First Degree Pacemaker Exit Block

    Directory of Open Access Journals (Sweden)

    Johnson Francis

    2016-10-01

    Full Text Available Usually atrial and ventricular depolarizations follow soon after the pacemaker stimulus (spike on the ECG. But there can be an exit block due to fibrosis at the electrode - tissue interface at the lead tip. This can increase the delay between the spike and atrial or ventricular depolarization.

  12. Building Blocks for Personal Brands

    Science.gov (United States)

    Thomas, Lisa Carlucci

    2011-01-01

    In this article, the author discusses the four essential building blocks for personal brands: (1) name; (2) message; (3) channels; and (4) bridges. However, outstanding building materials can only take a person so far. The author emphasizes that vision, determination, faith, a sense of humor, and humility are also required.

  13. Scattering matrices with block symmetries

    OpenAIRE

    Życzkowski, Karol

    1997-01-01

    Scattering matrices with block symmetry, which corresponds to scattering process on cavities with geometrical symmetry, are analyzed. The distribution of transmission coefficient is computed for different number of channels in the case of a system with or without the time reversal invariance. An interpolating formula for the case of gradual time reversal symmetry breaking is proposed.

  14. Building block filtering and mixing

    NARCIS (Netherlands)

    Kemenade, C.H.M. van

    1998-01-01

    A three-stage evolutionary method, the BBF-GA is introduced. BBF-GA is an acronym for building block filtering genetic algorithm. During the first stage, an ensemble of fast evolutionary algorithms is used to explore the search space. The best individual found by each of these evolutionary algorithm

  15. Preschoolers' Thinking during Block Play

    Science.gov (United States)

    Piccolo, Diana L.; Test, Joan

    2010-01-01

    Children build foundations for mathematical thinking in early play and exploration. During the preschool years, children enjoy exploring mathematical concepts--such as patterns, shape, spatial relationships, and measurement--leading them to spontaneously engage in mathematical thinking during play. Block play is one common example that engages…

  16. Layer-by-layer assembly of nanowires for three-dimensional, multifunctional electronics.

    Science.gov (United States)

    Javey, Ali; Nam, SungWoo; Friedman, Robin S; Yan, Hao; Lieber, Charles M

    2007-03-01

    We report a general approach for three-dimensional (3D) multifunctional electronics based on the layer-by-layer assembly of nanowire (NW) building blocks. Using germanium/silicon (Ge/Si) core/shell NWs as a representative example, ten vertically stacked layers of multi-NW field-effect transistors (FETs) were fabricated. Transport measurements demonstrate that the Ge/Si NW FETs have reproducible high-performance device characteristics within a given device layer, that the FET characteristics are not affected by sequential stacking, and importantly, that uniform performance is achieved in sequential layers 1 through 10 of the 3D structure. Five-layer single-NW FET structures were also prepared by printing Ge/Si NWs from lower density growth substrates, and transport measurements showed similar high-performance characteristics for the FETs in layers 1 and 5. In addition, 3D multifunctional circuitry was demonstrated on plastic substrates with sequential layers of inverter logical gates and floating gate memory elements. Notably, electrical characterization studies show stable writing and erasing of the NW floating gate memory elements and demonstrate signal inversion with larger than unity gain for frequencies up to at least 50 MHz. The ability to assemble reproducibly sequential layers of distinct types of NW-based devices coupled with the breadth of NW building blocks should enable the assembly of increasing complex multilayer and multifunctional 3D electronics in the future.

  17. Development of new layered selenide oxides with perovskite-type oxide layers

    Science.gov (United States)

    Ushiyama, Koichi; Ogino, Hiraku; Kishio, Kohji; Shimoyama, Jun-Ichi

    2010-03-01

    Several Fe-based superconductors with perovskite-type oxide layers, such as Sr2ScFePO3 (Tc ˜ 17 K)^[1], were discovered in our previous study. These compounds are composed of alternate stacking of superconducting layers with antifluorite structure and perovskite-type blocking layers. Since both layers are flexible in terms of chemical composition, development of various new functional materials can be expected from this family. In the present study, we have attempted to synthesize new layered selenide oxides with CuSe layers and discovered more than ten compounds, such as Sr2MCu2Se2O2 (M = Mn, Co, Ni, Cu, Zn) and Sr2MCuSeO3 (M = Sc, Cr, Mn, Fe, Ga, In), thus far. These indicated that the CuSe layer can accommodate various types of blocking layers, which may lead various functions. Among them, Sr2Cu3Se2O2 has a potential as for the mother compound of superconductor, if appropriate concentration of carrier is introduced to the CuO2 layer. Crystal structure and physical properties of these newly found compounds will be reported. [1] H. Ogino et al., Supercond. Sci. Technol. 22 (2009) 075008

  18. Pourfour Du Petit syndrome after interscalene block

    Directory of Open Access Journals (Sweden)

    Mysore Chandramouli Basappji Santhosh

    2013-01-01

    Full Text Available Interscalene block is commonly associated with reversible ipsilateral phrenic nerve block, recurrent laryngeal nerve block, and cervical sympathetic plexus block, presenting as Horner′s syndrome. We report a very rare Pourfour Du Petit syndrome which has a clinical presentation opposite to that of Horner′s syndrome in a 24-year-old male who was given interscalene block for open reduction and internal fixation of fracture upper third shaft of left humerus.

  19. Innovative masonry blocks for partition walls

    OpenAIRE

    Vasconcelos, Graça; Poletti, Elisa; Medeiros, Pedro; Mendonça, Paulo; Carvalho, Pedro; Cunha, Sandra Raquel Leite; Camões, Aires; Lourenço, Paulo B.

    2010-01-01

    This paper intends to propose a non structural system of partition walls with monolithic blocks based on a composite material resulting from an admixture of cork and textile fibers combined with a non cement binder, gypsum. These blocks consist of two half blocks which have to be connected during laying process. The developed blocks were first tested under compressive and flexural loading in order to derive their mechanical behaviour. Different curing conditions were applied to the blocks dur...

  20. Block Algorithms for Quark Propagator Calculation

    CERN Document Server

    Pickles, S M

    1998-01-01

    Computing quark propagators in lattice QCD is equivalent to solving large, sparse linear systems with multiple right-hand sides. Block algorithms attempt to accelerate the convergence of iterative Krylov-subspace methods by solving the multiple systems simultaneously. This paper compares a block generalisation of the quasi-minimal residual method (QMR), Block Conjugate Gradient on the normal equation, Block Lanczos and ($\\gamma_5$-symmetric) Block BiConjugate Gradient.

  1. Endoscopic sphenopalatine ganglion block for pain relief

    OpenAIRE

    Murty, P. S. N.; Prasanna, Atma

    1998-01-01

    The anaesthetic effect of the sphenopalatine (SPG) block has been well utilized for intranasal topical anaesthesia but the analgesic efficacy of (SPG) block, though well documented in literature, has not been put into practice. The methods available for SPG block till date were blind as they do not visualize the foramen. Nasal endoscopies have been used to visualize the foramen for an effective block. The authors present their experience with the endoscopic sphenopalatine ganglion block for p...

  2. Block Algorithms for Quark Propagator Calculation

    OpenAIRE

    Pickles, Stephen M.; Collaboration, UKQCD

    1997-01-01

    Computing quark propagators in lattice QCD is equivalent to solving large, sparse linear systems with multiple right-hand sides. Block algorithms attempt to accelerate the convergence of iterative Krylov-subspace methods by solving the multiple systems simultaneously. This paper compares a block generalisation of the quasi-minimal residual method (QMR), Block Conjugate Gradient on the normal equation, Block Lanczos and ($\\gamma_5$-symmetric) Block BiConjugate Gradient.

  3. Limiting Spectral Distribution of Block Matrices with Toeplitz Block Structure

    CERN Document Server

    Basu, Riddhipratim; Ganguly, Shirshendu; Hazra, Rajat Subhra

    2011-01-01

    We study two specific symmetric random block Toeplitz (of dimension $k \\times k$) matrices: where the blocks (of size $n \\times n$) are (i) matrices with i.i.d. entries, and (ii) asymmetric Toeplitz matrices. Under suitable assumptions on the entries, their limiting spectral distributions (LSDs) exist (after scaling by $\\sqrt{nk}$) when (a) $k$ is fixed and $n \\to\\infty$ (b) $n$ is fixed and $k\\rightarrow \\infty$ (c) $n$ and $k$ go to $\\infty$ simultaneously. Further the LSD's obtained in (a) and (b) coincide with those in (c) when $n$ or respectively $k$ tends to infinity. This limit in (c) is the semicircle law in case (i). In Case (ii) the limit is related to the limit of the random symmetric Toepiltz matrix as obtained by Bryc et al.(2006) and Hammond and Miller(2005).

  4. 3D Identification and Stability Analysis of Key Surface Blocks of Rock Slope

    Institute of Scientific and Technical Information of China (English)

    李明超; 周四宝; 王刚

    2016-01-01

    Complicated geological structures make it difficult to analyze the stability of rock slopes, such as faults, weak intercalated layers or joint fissures. Based on 3D geological modeling and surface block identifying methods, an integrated methodology framework was proposed and realized to analyze the stability of surface blocks in rock slopes. The surface blocks cut by geological structures, fissures or free faces could be identified subjected to the four principles of closure, completeness, uniqueness and validity. The factor of safety(FOS)of single key block was calculated by the limit equilibrium method. If there were two or more connected blocks, they were defined as a block-group. The FOS of a block-group was computed by the Sarma method. The proposed approach was applied to an actual rock slope of a hydropower project, and some possible instable blocks were demonstrated and analyzed visually. The obtained results on the key blocks or block-groups provide essential information for determining po-tential instable region of rock slopes and designing effective support scheme in advance.

  5. On the Eigenvalues and Eigenvectors of Block Triangular Preconditioned Block Matrices

    KAUST Repository

    Pestana, Jennifer

    2014-01-01

    Block lower triangular matrices and block upper triangular matrices are popular preconditioners for 2×2 block matrices. In this note we show that a block lower triangular preconditioner gives the same spectrum as a block upper triangular preconditioner and that the eigenvectors of the two preconditioned matrices are related. © 2014 Society for Industrial and Applied Mathematics.

  6. Cryptanalysis of Selected Block Ciphers

    DEFF Research Database (Denmark)

    Alkhzaimi, Hoda A.

    , pseudorandom number generators, and authenticated encryption designs. For this reason a multitude of initiatives over the years has been established to provide a secure and sound designs for block ciphers as in the calls for Data Encryption Standard (DES) and Advanced Encryption Standard (AES), lightweight...... ciphers initiatives, and the Competition for Authenticated Encryption: Security, Applicability, and Robustness (CAESAR). In this thesis, we first present cryptanalytic results on different ciphers. We propose attack named the Invariant Subspace Attack. It is utilized to break the full block cipher...... as truncated differentials. In addition to that, we also investigate the security of SIMON against different linear cryptanalysis methods, i.e., classic linear,and linear hull attacks. we present a connection between linear characteristic and differential characteristic, multiple linear and differential...

  7. Toy Blocks and Rotational Physics

    CERN Document Server

    Varieschi, G U; Varieschi, Gabriele U.; Jully, Isabel R.

    2004-01-01

    In this paper we summarize the theory of the "falling chimney," which deals with the breaking of tall structures in mid-air, when they fall to the ground. We describe how to reproduce these effects using small-scale models built with toy blocks. We also present an improved and more effective way to perform and analyze these interesting experiments, by using video capture software together with a digital video camera.

  8. Compact planar microwave blocking filters

    Science.gov (United States)

    U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)

    2012-01-01

    A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.

  9. A conformal block Farey tail

    CERN Document Server

    Maloney, Alexander; Ng, Gim Seng

    2016-01-01

    We investigate the constraints of crossing symmetry on CFT correlation functions. Four point conformal blocks are naturally viewed as functions on the upper-half plane, on which crossing symmetry acts by PSL(2,Z) modular transformations. This allows us to construct a unique, crossing symmetric function out of a given conformal block by averaging over PSL(2,Z). In some two dimensional CFTs the correlation functions are precisely equal to the modular average of the contributions of a finite number of light states. For example, in the two dimensional Ising and tri-critical Ising model CFTs, the correlation functions of identical operators are equal to the PSL(2,Z) average of the Virasoro vacuum block; this determines the 3 point function coefficients uniquely in terms of the central charge. The sum over PSL(2,Z) in CFT2 has a natural AdS3 interpretation as a sum over semi-classical saddle points, which describe particles propagating along rational tangles in the bulk. We demonstrate this explicitly for the corre...

  10. Some new construction methods of variance balanced block designs with repeated blocks

    OpenAIRE

    Ceranka, Bronisław; Graczyk, Małgorzata

    2014-01-01

    Some new construction methods of the variance balanced block designs with repeated blocks are given. They are based on the specialized product of incidence matrices of the balanced incomplete block designs.

  11. Cascade recursion models of computing the temperatures of underground layers

    Institute of Scientific and Technical Information of China (English)

    HAN Liqun; BI Siwen; SONG Shixin

    2006-01-01

    An RBF neural network was used to construct computational models of the underground temperatures of different layers, using ground-surface parameters and the temperatures of various underground layers. Because series recursion models also enable researchers to use above-ground surface parameters to compute the temperatures of different underground layers, this method provides a new way of using thermal infrared remote sensing to monitor the suture zones of large areas of blocks and to research thermal anomalies in geologic structures.

  12. Morphological Heterogeneity of Layer VI Neurons in Mouse Barrel Cortex

    OpenAIRE

    Chen, Chia-Chien; Abrams, Svetlana; Pinhas, Alex; Brumberg, Joshua C.

    2009-01-01

    Understanding the basic neuronal building blocks of the neocortex is a necessary first step toward comprehending the composition of cortical circuits. Neocortical layer VI is the most morphologically diverse layer and plays a pivotal role in gating information to the cortex via its feedback connection to the thalamus and other ipsilateral and callosal corticocortical connections. The heterogeneity of function within this layer is presumably linked to its varied morphological composition. Howe...

  13. Electrically Tunable Soft-Solid Block Copolymer Structural Color.

    Science.gov (United States)

    Park, Tae Joon; Hwang, Sun Kak; Park, Sungmin; Cho, Sung Hwan; Park, Tae Hyun; Jeong, Beomjin; Kang, Han Sol; Ryu, Du Yeol; Huh, June; Thomas, Edwin L; Park, Cheolmin

    2015-12-22

    One-dimensional photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid (IL) swollen block copolymer (BCP) films. Placement of a polymer/ionic liquid film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2-vinylpyridine) (PS-b-QP2VP) copolymer SC film allowed the development of red (R), green (G), and blue (B) full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3 to +6 V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device. PMID:26505787

  14. Demographic Data - MDC_BlockGroup

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — A polygon feature class of Miami-Dade County Census 2000 Block Groups. A census Block Group is a statistical subdivision of a census Tract consisting of a cluster...

  15. Multigrid Methods for General Block Toeplitz Matrices

    OpenAIRE

    Thomas Huckle; Jochen Staudacher

    2016-01-01

    In this paper we discuss multigrid methods for symmetric positive definite Block Toeplitz matrices. Our Block Toeplitz systems are general in the sense that the individual blocks are not necessarily Toeplitz. We investigate how transfer operators for prolongation and restriction have to be chosen such that our multigrid algorithms converge quickly. We will point out why these transfer operators can be understood as block matrices as well. We explain how our new algorithms can also be combined...

  16. Excitation block in a nerve fibre model owing to potassium-dependent changes in myelin resistance

    DEFF Research Database (Denmark)

    Brazhe, Alexey; Maksimov, G. V.; Mosekilde, Erik;

    2011-01-01

    The myelinated nerve fibre is formed by an axon and Schwann cells or oligodendrocytes that sheath the axon by winding around it in tight myelin layers. Repetitive stimulation of a fibre is known to result in accumulation of extracellular potassium ions, especially between the axon and the myelin......-spiking states. Intermittent conduction blocks are accompanied by oscillations of extracellular potassium. The mechanism of conductance block based on myelin restructuring complements the already known and modelled block via hyperpolarization mediated by the axonal sodium pump and potassium depolarization....

  17. New Considerations of Turbo Block Codes

    Institute of Scientific and Technical Information of China (English)

    YUEDianwu; EdSHWEDYK

    2004-01-01

    It is shown that (1) a general linear systematic block code can be expressed as a turbo block code and therefore can be decoded using any turbo decoding algorithm; (2) a turbo block code can be also encoded and decoded without any interleaver with the same performance as when an interleaver is present.

  18. Bullet-Block Science Video Puzzle

    Science.gov (United States)

    Shakur, Asif

    2015-01-01

    A science video blog, which has gone viral, shows a wooden block shot by a vertically aimed rifle. The video shows that the block hit dead center goes exactly as high as the one shot off-center. (Fig. 1). The puzzle is that the block shot off-center carries rotational kinetic energy in addition to the gravitational potential energy. This leads a…

  19. Block Play: Practical Suggestions for Common Dilemmas

    Science.gov (United States)

    Tunks, Karyn Wellhousen

    2009-01-01

    Learning materials and teaching methods used in early childhood classrooms have fluctuated greatly over the past century. However, one learning tool has stood the test of time: Wood building blocks, often called unit blocks, continue to be a source of pleasure and learning for young children at play. Wood blocks have the unique capacity to engage…

  20. Interactions between plasma and block copolymers used in directed self-assembly patterning

    Science.gov (United States)

    Sirard, Stephen; Azarnouche, Laurent; Gurer, Emir; Durand, William; Maher, Michael; Mori, Kazunori; Blachut, Gregory; Janes, Dustin; Asano, Yusuke; Someya, Yasunobu; Hymes, Diane; Graves, David; Ellison, Christopher J.; Willson, C. Grant

    2016-03-01

    The directed self-assembly (DSA) of block copolymers offers a promising route for scaling feature sizes below 20 nm. At these small dimensions, plasmas are often used to define the initial patterns. It is imperative to understand how plasmas interact with each block in order to design processes with sufficient etch contrast and pattern fidelity. Symmetric lamella forming block copolymers including, polystyrene-b-poly(methyl methacrylate) and several high-χ silicon-containing and tin-containing block copolymers were synthesized, along with homopolymers of each block, and exposed to various oxidizing, reducing, and fluorine-based plasma processes. Etch rate kinetics were measured, and plasma modifications of the materials were characterized using XPS, AES, and FTIR. Mechanisms for achieving etch contrast were elucidated and were highly dependent on the block copolymer architecture. For several of the polymers, plasma photoemissions were observed to play an important role in modifying the materials and forming etch-resistant protective layers. Furthermore, it was observed for the silicon- and tin-containing polymers that an initial transient state exists, where the polymers exhibit an enhanced etch rate, prior to the formation of the etch-resistant protective layer. Plasma developed patterns were demonstrated for the differing block copolymer materials with feature sizes ranging from 20 nm down to approximately 5 nm.

  1. The presence of thrust-block naled after a major surge event: Kuannersuit Glacier, West Greenland

    Science.gov (United States)

    Yde, Jacob C.; Knudsen, N. Tvis; Larsen, Nicolaj K.; Kronborg, Christian; Nielsen, Ole B.; Heinemeier, Jan; Olsen, Jesper

    Thrust-block naled in front of Kuannersuit Glacier, West Greenland, appears to have formed during the termination of a terrestrial surge event by a combination of enhanced winter runoff, rapid advance of the glacier terminus, and proglacial stress release by thrusting and stacking of naled blocks. This process is equivalent to the formation of thrust-block moraines. The thrust-block naled consists of at least seven thrust sheets, which are characterized by stratified ice with beds composed of a lower debris-rich lamina, an intermediate dispersed lamina and a top clean-ice lamina, and underlain by frozen outwash deposits. The thrust-block naled differs from basal stratified ice in the absence of internal deformation structures, a relatively low debris concentration, a clay-rich particle-size distribution and a preferential sorting of lighter minerals. The oxygen isotope composition of the thrust-block naled is indistinguishable from δ18O values from meteoric glacier ice and bulk meltwater, but different from basal stratified ice facies. The d-δD relationship indicates that thrust-block naled has been formed by freezing of successive thin layers of bulk waters with variable isotopic composition, whereas basal stratified ice has developed in a subglacial environment with regelation. This work shows that the association between proglacial naled and rapidly advancing glaciers may have significant consequences for the proglacial geomorphology and the interpretation of basal ice layers.

  2. Isostatic compression of buffer blocks. Middle scale

    Energy Technology Data Exchange (ETDEWEB)

    Ritola, J.; Pyy, E. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2012-01-15

    Manufacturing of buffer components using isostatic compression method has been studied in small scale in 2008 (Laaksonen 2010). These tests included manufacturing of buffer blocks using different bentonite materials and different compression pressures. Isostatic mould technology was also tested, along with different methods to fill the mould, such as vibration and partial vacuum, as well as a stepwise compression of the blocks. The development of manufacturing techniques has continued with small-scale (30 %) blocks (diameter 600 mm) in 2009. This was done in a separate project: Isostatic compression, manufacturing and testing of small scale (D = 600 mm) buffer blocks. The research on the isostatic compression method continued in 2010 in a project aimed to test and examine the isostatic manufacturing process of buffer blocks at 70 % scale (block diameter 1200 to 1300 mm), and the aim was to continue in 2011 with full-scale blocks (diameter 1700 mm). A total of nine bentonite blocks were manufactured at 70 % scale, of which four were ring-shaped and the rest were cylindrical. It is currently not possible to manufacture full-scale blocks, because there is no sufficiently large isostatic press available. However, such a compression unit is expected to be possible to use in the near future. The test results of bentonite blocks, produced with an isostatic pressing method at different presses and at different sizes, suggest that the technical characteristics, for example bulk density and strength values, are somewhat independent of the size of the block, and that the blocks have fairly homogenous characteristics. Water content and compression pressure are the two most important properties determining the characteristics of the compressed blocks. By adjusting these two properties it is fairly easy to produce blocks at a desired density. The commonly used compression pressure in the manufacturing of bentonite blocks is 100 MPa, which compresses bentonite to approximately

  3. Ganglion block. When and how?

    International Nuclear Information System (INIS)

    Increasing understanding of the anatomy and physiology of neural structures has led to the development of surgical and percutaneous neurodestructive methods in order to target and destroy various components of afferent nociceptive pathways. The dorsal root ganglia and in particular the ganglia of the autonomous nervous system are targets for radiological interventions. The autonomous nervous system is responsible for the regulation of organ functions, sweating, visceral and blood vessel-associated pain. Ganglia of the sympathetic chain and non-myelinized autonomous nerves can be irreversibly destroyed by chemical and thermal ablation. Computed tomography (CT)-guided sympathetic nerve blocks are well established interventional radiological procedures which lead to vasodilatation, reduction of sweating and reduction of pain associated with the autonomous nervous system. Sympathetic blocks are applied for the treatment of various vascular diseases including critical limb ischemia. Other indications for thoracic and lumbar sympathectomy include complex regional pain syndrome (CRPS), chronic tumor associated pain and hyperhidrosis. Neurolysis of the celiac plexus is an effective palliative pain treatment particularly in patients suffering from pancreatic cancer. Percutaneous dorsal root ganglion rhizotomy can be performed in selected patients with radicular pain that is resistant to conventional pharmacological and interventional treatment. (orig.)

  4. Seismicity of the Jalisco Block

    Science.gov (United States)

    Nunez-Cornu, F. J.; Rutz, M.; Camarena-Garcia, M.; Trejo-Gomez, E.; Reyes-Davila, G.; Suarez-Plascencia, C.

    2002-12-01

    In April 2002 began to transmit the stations of the first phase of Jalisco Telemetric Network located at the northwest of Jalisco Block and at the area of Volcan de Fuego (Colima Volcano), in June were deployed four additional MarsLite portable stations in the Bahia de Banderas area, and by the end of August one more portable station at Ceboruco Volcano. The data of these stations jointly with the data from RESCO (Colima Telemetric Network) give us the minimum seismic stations coverage to initiate in a systematic and permanent way the study of the seismicity in this very complex tectonic region. A preliminary analysis of seismicity based on the events registered by the networks using a shutter algorithm, confirms several important features proposed by microseismicity studies carried out between 1996 and 1998. A high level of seismicity inside and below of Rivera plate is observed, this fact suggest a very complex stress pattern acting on this plate. Shallow seismicity at south and east of Bahia de Banderas also suggest a complex stress pattern in this region of the Jalisco Block, events at more than 30 km depth are located under the mouth of the bay and in face of it, a feature denominated Banderas Boundary mark the change of the seismic regime at north of this latitude (20.75°N), however some shallow events were located at the region of Nayarit.

  5. Composite S-layer lipid structures.

    Science.gov (United States)

    Schuster, Bernhard; Sleytr, Uwe B

    2009-10-01

    Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state of the art survey how S-layer proteins, lipids, and polysaccharides may be used as basic building blocks for the assembly of S-layer supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas for application of composite S-layer membrane systems concern sensor systems involving specific membrane functions. PMID:19303933

  6. General Floorplans with L/T-Shaped Blocks Using Corner Block List

    Institute of Scientific and Technical Information of China (English)

    Yu-Chun Ma; Xian-Long Hong; She-Qin Dong; C.K.Cheng; Jun Gu

    2006-01-01

    With the recent advent of deep submicron technology and new packing schemes, the components in the integrated circuit are often not rectangular. On the basis of the representation of Corner Block List (CBL), we propose a new method of handling rectilinear blocks. In this paper, the handling of the rectilinear blocks is simplified by transforming the L/T-shaped block problem into the align-abutment constraint problem. We devise the block rejoining process and block alignment operation for forming the L/T-shaped blocks into their original configurations. The shape flexibility of the soft blocks, and the rotation and reflection of L/T-shaped blocks are exploited to obtain a tight packing. The empty rooms are introduced to the process of block rejoining. The efficiency and effectiveness of the proposed method are demonstrated by the experimental results on a set of some benchmark examples.

  7. Double smectic self-assembly in block copolypeptide complexes

    KAUST Repository

    Haataja, Johannes S.

    2012-11-12

    We show double smectic-like self-assemblies in the solid state involving alternating layers of different polypeptide α-helices. We employed rod-coil poly(γ-benzyl l-glutamate)-block-poly(l-lysine) (PBLG-b-PLL) as the polymeric scaffold, where the PLL amino residues were ionically complexed to di-n-butyl phosphate (diC4P), di(2-ethylhexyl) phosphate (diC2/6P), di(2-octyldodecyl) phosphate (diC8/12P), or di-n-dodecyl phosphate (diC12P), forming PBLG-b-PLL(diC4P), PBLG-b-PLL(diC2/6P), PBLG-b-PLL(diC8/12P), and PBLG-b-PLL(diC12P) complexes, respectively. The complexes contain PBLG α-helices of fixed diameter and PLL-surfactant complexes adopting either α-helices of tunable diameters or β-sheets. For PBLG-b-PLL(diC4P), that is, using a surfactant with short n-butyl tails, both blocks were α-helical, of roughly equal diameter and thus with minor packing frustrations, leading to alternating PBLG and PLL(diC4P) smectic layers of approximately perpendicular alignment of both types of α-helices. Surfactants with longer and branched alkyl tails lead to an increased diameter of the PLL-surfactant α-helices. Smectic alternating PBLG and PLL(diC2/6P) layers involve larger packing frustration, which leads to poor overall order and suggests an arrangement of tilted PBLG α-helices. In PBLG-b-PLL(diC8/12P), the PLL(diC8/12P) α-helices are even larger and the overall structure is poor. Using a surfactant with two linear n-dodecyl tails leads to well-ordered β-sheet domains of PLL(diC12P), consisting of alternating PLL and alkyl chain layers. This dominates the whole assembly, and at the block copolypeptide length scale, the PBLG α-helices do not show internal order and have poor organization. Packing frustration becomes an important aspect to design block copolypeptide assemblies, even if frustration could be relieved by conformational imperfections. The results suggest pathways to control hierarchical liquid-crystalline assemblies by competing interactions and by

  8. Mg intercalation into Ti2C building block

    Science.gov (United States)

    Yu, Xue-fang; Cheng, Jianbo; Liu, Zhenbo; Li, Qingzhong; Li, Wenzuo; Yang, Xin; Xiao, Bo

    2015-06-01

    Generally, intercalation occurs when foreign atoms intercalate into multi-layer structures, while adsorption occurs when foreign atoms interact with monolayer structures or surfaces. We performed an investigation on the Mg intercalation into Ti2C building block (MXene) from first-principles simulation. We found that Mg can favorably intercalate into MXene, forming the stable compound Ti2MgC, which corresponds to the stage I in the Li intercalation into graphite. Based on the evaluation of the average cell potential and the energy barrier of Mg diffusion for the most energetically stable structure, our results suggest that Ti2MgC is a potential anode for Mg ion batteries.

  9. Computing eigenvectors of block tridiagonal matrices based on twisted block factorizations

    OpenAIRE

    König, Gerhard; Moldaschl, Michael; Gansterer, Wilfried N.

    2012-01-01

    New methods for computing eigenvectors of symmetric block tridiagonal matrices based on twisted block factorizations are explored. The relation of the block where two twisted factorizations meet to an eigenvector of the block tridiagonal matrix is reviewed. Based on this, several new algorithmic strategies for computing the eigenvector efficiently are motivated and designed. The underlying idea is to determine a good starting vector for an inverse iteration process from the twisted block fact...

  10. A comparison between caudal block versus splash block for postoperative analgesia following inguinal herniorrhaphy in children

    OpenAIRE

    Cheon, Jun Kong; Park, Cheon Hee; Hwang, Kan Taeck; Choi, Bo Yoon

    2011-01-01

    Background We wanted to determine the postoperative analgesic efficacy of preincisional caudal epidural block versus instillation (splash block) following inguinal herniorrhaphy in children. Methods Thirty children (age range: 1-7 years) who were scheduled to undergo inguinal herniorrhaphy were divided into 2 groups: the caudal block group and the splash block group with 15 children in each group. Tracheal intubation was performed. Fifteen children received caudal block with 1.0 ml/kg of 0.25...

  11. Used, Blocking and Sleeping Patents

    DEFF Research Database (Denmark)

    Torrisi, Salvatore; Gambardella, Alfonso; Giuri, Paola;

    2016-01-01

    This paper employs data from a large-scale survey (InnoS&T) of inventors in Europe, the USA, and Japan who were listed in patent applications filed at the European Patent Office with priority years between 2003 and 2005. We provide evidence regarding the reasons for patenting and the ways in which...... patents are being utilized. A substantial share of patents is neither used internally nor for market transactions, which confirms the importance of strategic patenting and inefficiency in the management of intellectual property. We investigate different types of unused patents—unused blocking patents...... and sleeping patents. We also examine the association between used and unused patents and their characteristics such as family size, scope, generality and overlapping claims, technology area, type of applicant, and the competitive environment from where these patents originate. We discuss our results...

  12. Kinking mechanisms in block copolymers

    Science.gov (United States)

    Polis, Daniel L.; Winey, Karen I.

    1998-03-01

    Two of the primary models proposed for kink formation are fixed hinge rotation and boundary migration. Our results regarding steady shear induced kink bands in an aligned lamellar poly(styrene-b-ethylene propylene) diblock copolymer are consistent with a fixed hinge rotation mechanism. When the shear strain is above a critical strain, a range of kink widths and kink angles are produced at each shear rate studied. Moreover, the kink widths are independent of rate and strain, having a characteristic size similar to that of remaining defects in the initially aligned block copolymer. Rounded folds, similar in size, shape, and orientation to kink bands, are produced at these residual defects at shear strains below the critical stain. These rounded folds may sharpen into angular folds or kink bands with additional strain.

  13. Building blocks of e-commerce

    OpenAIRE

    Rajaraman, V.

    2005-01-01

    This article examines the architecture of e-commerce as a set of layers, each supporting the one above it. The layers have clean interfaces, that is, they can be designed independently. We present an architecture with six layers. The lowest layer consists of a physical communication network such as local area network or public switched telephone networks. The next higher layer is the logical layer which describes the protocol used to interconnect communication systems to create internet, intr...

  14. Updating the QR decomposition of block tridiagonal and block Hessenberg matrices generated by block Krylov space methods

    OpenAIRE

    Gutknecht, Martin; Schmelzer, Thomas

    2005-01-01

    For MINRES and SYMMLQ it is essential to compute the QR decompositions of tridiagonal coefficient matrices gained in the Lanczos process. Likewise, for GMRES one has to find those of Hessenberg matrices. These QR decompositions are computed by an update scheme where in every step a single Givens rotation is constructed. Generalizing this approach we introduce a block-wise update scheme for the QR decomposition of the block tridiagonal and block Hessenberg matrices that come up in generalizati...

  15. Block copolymer modified surfaces for conjugation of biomacromolecules with control of quantity and activity.

    Science.gov (United States)

    Li, Xin; Wang, Mengmeng; Wang, Lei; Shi, Xiujuan; Xu, Yajun; Song, Bo; Chen, Hong

    2013-01-29

    Polymer brush layers based on block copolymers of poly(oligo(ethylene glycol) methacrylate) (POEGMA) and poly(glycidyl methacrylate) (PGMA) were formed on silicon wafers by activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). Different types of biomolecule can be conjugated to these brush layers by reaction of PGMA epoxide groups with amino groups in the biomolecule, while POEGMA, which resists nonspecific protein adsorption, provides an antifouling environment. Surfaces were characterized by water contact angle, ellipsometry, and Fourier transform infrared spectroscopy (FTIR) to confirm the modification reactions. Phase segregation of the copolymer blocks in the layers was observed by AFM. The effect of surface properties on protein conjugation was investigated using radiolabeling methods. It was shown that surfaces with POEGMA layers were protein resistant, while the quantity of protein conjugated to the diblock copolymer modified surfaces increased with increasing PGMA layer thickness. The activity of lysozyme conjugated on the surface could also be controlled by varying the thickness of the copolymer layer. When biotin was conjugated to the block copolymer grafts, the surface remained resistant to nonspecific protein adsorption but showed specific binding of avidin. These properties, that is, well-controlled quantity and activity of conjugated biomolecules and specificity of interaction with target biomolecules may be exploited for the improvement of signal-to-noise ratio in sensor applications. More generally, such surfaces may be useful as biological recognition elements of high specificity for functional biomaterials. PMID:23265296

  16. Nanostructured Polysulfone-Based Block Copolymer Membranes

    KAUST Repository

    Xie, Yihui

    2016-05-01

    The aim of this work is to fabricate nanostructured membranes from polysulfone-based block copolymers through self-assembly and non-solvent induced phase separation. Block copolymers containing polysulfone are novel materials for this purpose providing better mechanical and thermal stability to membranes than polystyrene-based copolymers, which have been exclusively used now. Firstly, we synthesized a triblock copolymer, poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) through polycondensation and reversible addition-fragmentation chain-transfer polymerization. The obtained membrane has a highly porous interconnected skin layer composed of elongated micelles with a flower-like arrangement, on top of the graded finger-like macrovoids. Membrane surface hydrolysis was carried out in a combination with metal complexation to obtain metal-chelated membranes. The copper-containing membrane showed improved antibacterial capability. Secondly, a poly(acrylic acid)-b-polysulfone-b-poly(acrylic acid) triblock copolymer obtained by hydrolyzing poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) formed a thin film with cylindrical poly(acrylic acid) microdomains in polysulfone matrix through thermal annealing. A phase inversion membrane was prepared from the same polymer via self-assembly and chelation-assisted non-solvent induced phase separation. The spherical micelles pre-formed in a selective solvent mixture packed into an ordered lattice in aid of metal-poly(acrylic acid) complexation. The space between micelles was filled with poly(acrylic acid)-metal complexes acting as potential water channels. The silver0 nanoparticle-decorated membrane was obtained by surface reduction, having three distinct layers with different particle sizes. Other amphiphilic copolymers containing polysulfone and water-soluble segments such as poly(ethylene glycol) and poly(N-isopropylacrylamide) were also synthesized through coupling reaction and copper0-mediated

  17. Electric double layer of anisotropic dielectric colloids under electric fields

    Science.gov (United States)

    Han, M.; Wu, H.; Luijten, E.

    2016-07-01

    Anisotropic colloidal particles constitute an important class of building blocks for self-assembly directed by electrical fields. The aggregation of these building blocks is driven by induced dipole moments, which arise from an interplay between dielectric effects and the electric double layer. For particles that are anisotropic in shape, charge distribution, and dielectric properties, calculation of the electric double layer requires coupling of the ionic dynamics to a Poisson solver. We apply recently proposed methods to solve this problem for experimentally employed colloids in static and time-dependent electric fields. This allows us to predict the effects of field strength and frequency on the colloidal properties.

  18. Model Research On Synthesis Of Al2O3-C Layers By MOCVD

    Directory of Open Access Journals (Sweden)

    Sawka A.

    2015-06-01

    Full Text Available These are model studies whose aim is to obtain information that would allow development of new technology for synthesizing monolayers of Al2O3-C with adjusted microstructure on cemented carbides. The Al2O3-C layer will constitute an intermediate layer on which the outer layer of Al2O3 without carbon is synthesized. The purpose of the intermediate layer is to block the cobalt diffusion to the synthesized outer layer of Al2O3 and to stop the diffusion of air oxygen to the substrate during the synthesis of the outer layer. This layer should be thin, continuous, dense and uniform in thickness.

  19. Functional Nanoporous Polymers from Block Copolymer Precursors

    OpenAIRE

    Guo, Fengxiao

    2010-01-01

    Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential applications as, e.g., membranes for separation and purification, templates for nanostructured materials, sensors, substrates for catalysis, low dielectric constant materials, photonic materials, and...

  20. Block methods for linear Hamiltonian systems

    OpenAIRE

    Tian, Hongjiong; Chen, Bailin

    2014-01-01

    For the numerical treatment of Hamiltonian differential equations,symplectic integrators are regarded as the most suitable choice.In this paper we are concerned with the applicability of block methods for the discrete approximate solution of linear Hamiltonian systems.The k-dimensional block methods are convergent of order at least k+1 for ordinary differential equations.We provide conditions on the coefficients of the equivalent block methods in order to maintain two important properties of...

  1. Advanced heart block in acute rheumatic fever

    OpenAIRE

    Hubail, Zakariya; Ebrahim, Ishaq M.

    2015-01-01

    First degree heart block is considered a minor criterion for the diagnosis of this condition. The cases presented here demonstrate that higher degrees of heart block do occur in rheumatic fever. Children presenting with acquired heart block should be worked-up for rheumatic fever. Likewise, it is imperative to serially follow the electrocardiogram in patients already diagnosed with acute rheumatic fever, as the conduction abnormalities can change during the course of the disease.

  2. LEO resistant PI-B-PDMS block copolymer films for solar array applications

    NARCIS (Netherlands)

    Lonkhuyzen, H. van; Bongers, E.; Fischer, H.R.; Dingemans, T.J.; Semprimoschnig, C.

    2013-01-01

    Due to their low atomic oxygen erosion yields PI-b-PDMS block copolymer films have considerable potential for application onto space exposed surfaces of satellites in low earth orbit. On solar arrays these materials might be used as electrical electrical insulation film, flexprint outer layer, elect

  3. Rapid, Brushless Self-assembly of a PS-b-PDMS Block Copolymer for Nanolithography

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu;

    2014-01-01

    antidot patterns after short solvo-thermal annealing. Unlike previous reports on this system, low temperature and short annealing time provide self-assembly in homogeneous thin films covering large substrate areas. This on-chip mask was then used for pattern transfer to the underlying silicon substrate......Block copolymers (BCP) are highly promising self-assembling precursors for scalable nanolithography. Very regular BCP nanopatterns can be used as on-chip etch masks. The first step in the processing of BCP thin films is usually the chemical modification of the substrate surface, typically by...... grafting of a brush layer that renders the surface energy neutral relative to the constituent blocks. We provide here a first study on rapid, low temperature self-assembly of PS-b-PDMS (polystyrene-block-polydimethylsiloxane) on silicon substrates without a brush layer. We show that it forms line and...

  4. Using Interference to Block RFID Tags

    DEFF Research Database (Denmark)

    Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund;

    We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag.......We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag....

  5. Recent developments in paediatric neuraxial blocks

    Directory of Open Access Journals (Sweden)

    Vrushali Chandrashekhar Ponde

    2012-01-01

    Full Text Available Paediatric anaesthesia and paediatric regional anaesthesia are intertwined. Almost all surgeries unless contradicted could be and should be supplemented with a regional block. The main objective of this review is to elaborate on the recent advances of the central neuraxial blocks, such as application of ultrasound guidance and electrical stimulation in the pursuit of safety and an objective end point. This review also takes account of the traditional technique and understand the benefits as well the risk of each as compared with the recent technique. The recent trends in choosing the most appropriate peripheral block for a given surgery thereby sparing the central neuroaxis is considered. A penile block for circumcision or a sciatic block for unilateral foot surgery, rather than caudal epidural would have a better risk benefit equation. Readers will find a special mention on the recent thoughts on continuous epidural analgesia in paediatrics, especially its rise and fall, yet its unique importance. Lastly, the issue of block placements under sedation or general anaesthesia with its implication in this special population is dealt with. We conducted searches in MEDLINE (PubMed and assessed the relevance of the abstracts of citations identified from literature searches. The search was carried out in English, for last 10 years, with the following key words: Recent advances in paediatric regional anaesthesia; ultrasound guidance for central neuraxial blocks in children; role of electrical stimulation in neuraxial blocks in children; complications in neuraxial block. Full-text articles of potentially relevant abstracts were retrieved for further review.

  6. A New Relationship between Block Designs

    Directory of Open Access Journals (Sweden)

    Alexander Shramchenko

    2016-01-01

    Full Text Available We propose a procedure of constructing new block designs starting from a given one by looking at the intersections of its blocks with various sets and grouping those sets according to the structure of the intersections. We introduce a symmetric relationship of friendship between block designs built on a set V and consider families of block designs where all designs are friends of each other, the so-called friendly families. We show that a friendly family admits a partial ordering. Furthermore, we exhibit a map from the power set of V, partially ordered by inclusion, to a friendly family of a particular type which preserves the partial order.

  7. PACS photometer calibration block analysis

    CERN Document Server

    Moór, A; Kiss, Cs; Balog, Z; Billot, N; Marton, G

    2013-01-01

    The absolute stability of the PACS bolometer response over the entire mission lifetime without applying any corrections is about 0.5% (standard deviation) or about 8% peak-to-peak. This fantastic stability allows us to calibrate all scientific measurements by a fixed and time-independent response file, without using any information from the PACS internal calibration sources. However, the analysis of calibration block observations revealed clear correlations of the internal source signals with the evaporator temperature and a signal drift during the first half hour after the cooler recycling. These effects are small, but can be seen in repeated measurements of standard stars. From our analysis we established corrections for both effects which push the stability of the PACS bolometer response to about 0.2% (stdev) or 2% in the blue, 3% in the green and 5% in the red channel (peak-to-peak). After both corrections we still see a correlation of the signals with PACS FPU temperatures, possibly caused by parasitic h...

  8. Dynamical Analysis of Blocking Events: Spatial and Temporal Fluctuations of Covariant Lyapunov Vectors

    CERN Document Server

    Schubert, Sebastian

    2015-01-01

    One of the most relevant weather regimes in the mid latitudes atmosphere is the persistent deviation from the approximately zonally symmetric jet stream to the emergence of so-called blocking patterns. Such configurations are usually connected to exceptional local stability properties of the flow which come along with an improved local forecast skills during the phenomenon. It is instead extremely hard to predict onset and decay of blockings. Covariant Lyapunov Vectors (CLVs) offer a suitable characterization of the linear stability of a chaotic flow, since they represent the full tangent linear dynamics by a covariant basis which explores linear perturbations at all time scales. Therefore, we will test whether CLVs feature a signature of the blockings. We examine the CLVs for a quasi-geostrophic beta-plane two-layer model in a periodic channel baroclinically driven by a meridional temperature gradient $\\Delta T$. An orographic forcing enhances the emergence of localized blocked regimes. We detect the blockin...

  9. BTP: a Block Transfer Protocol for Delay Tolerant Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Hansen, Morten Tranberg; Biagioni, Edoardo S.

    2010-01-01

    communicate to senders how many packets they are prepared to accept, providing a flow control mechanism to exert back-pressure on the senders. BTP has been evaluated on a real sensor node platform, as well as in simulation.  BTP reduces the average time to transfer blocks of $60$ packets, each 41 bytes long......Wireless sensor networks that are energy-constrained must transmit and receive data as efficiently as possible.  If the transmission is delay tolerant, transferring blocks of accumulated data can be more efficient than transferring each sensed measurement as soon as it is available.  This paper...... proposes a Block Transfer Protocol (BTP) designed for efficient and reliable transmission in wireless sensor networks.  BTP reduces the time it takes to reliably transfer a block of packets compared to conventional link layer protocols, by piggybacking in data packets information about the transfer...

  10. Restoration and Preservation of Engraved Limestone Blocks Discovered in Abu Mousa Excavation, Suez - Egypt

    Directory of Open Access Journals (Sweden)

    Nabil A. Abd El-Tawab BADER

    2013-03-01

    Full Text Available A lot of engraved limestone blocks were discovered at Awlad Abu Musa (east of Suez, Egypt in 1995/2007 by Supreme Council of Antiquities. The stone blocks were seriously affected by archaeological environments during burial environment in agriculture land. They were covered with thick clay layer with soil particles that disfigured them and hid their inscriptions. Prior to the conservation intervention, the materials were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Chemical analyses of ground water and microbiological study. After the material characterization, the conservation and restoration of the stone blocks were carried out including cleaning, consolidation, reduction of salts, Re-jointing, restoration and completion of lost parts. After that the blocks were exhibited in Suez museum.

  11. Infrared imaging video bolometer with a double layer absorbing foil

    International Nuclear Information System (INIS)

    The object of the present paper is an infrared video bolometer with a bolometer foil consisting of two layers: the first layer is constructed of radiation absorbing blocks and the second layer is a thermal isolating base. The absorbing blocks made of a material with a high photon attenuation coefficient (gold) were spatially separated from each other while the base should be made of a material having high tensile strength and low thermal conductance (stainless steel). Such a foil has been manufactured in St. Petersburg and calibrated in NIFS using a vacuum test chamber and a laser beam as an incident power source. A finite element method (FEM) code was applied to simulate the thermal response of the foil. Simulation results are in good agreement with the experimental calibration data. The temperature response of the double layer foil is a factor of two higher than that of a single foil IR video bolometer using the same absorber material and thickness. (author)

  12. Dynamical Analysis of Blocking Events: Spatial and Temporal Fluctuations of Covariant Lyapunov Vectors

    Science.gov (United States)

    Schubert, Sebastian; Lucarini, Valerio

    2016-04-01

    One of the most relevant weather regimes in the mid latitudes atmosphere is the persistent deviation from the approximately zonally symmetric jet stream to the emergence of so-called blocking patterns. Such configurations are usually connected to exceptional local stability properties of the flow which come along with an improved local forecast skills during the phenomenon. It is instead extremely hard to predict onset and decay of blockings. Covariant Lyapunov Vectors (CLVs) offer a suitable characterization of the linear stability of a chaotic flow, since they represent the full tangent linear dynamics by a covariant basis which explores linear perturbations at all time scales. Therefore, we will test whether CLVs feature a signature of the blockings. We examine the CLVs for a quasi-geostrophic beta-plane two-layer model in a periodic channel baroclinically driven by a meridional temperature gradient ΔT. An orographic forcing enhances the emergence of localized blocked regimes. We detect the blocking events of the channel flow with a Tibaldi-Molteni scheme adapted to the periodic channel. When blocking occurs, the global growth rates of the fastest growing CLVs are significantly higher. Hence against intuition, globally the circulation is more unstable in blocked phases. Such an increase in the finite time Lyapunov exponents with respect to the long term average is attributed to stronger barotropic and baroclinic conversion in the case of high temperature gradients, while for low values of ΔT, the effect is only due to stronger barotropic instability. For the localization of the CLVs, we compare the meridionally averaged variance of the CLVs during blocked and unblocked phases. We find that on average the variance of the CLVs is clustered around the center of blocking. These results show that the blocked flow affects all time scales and processes described by the CLVs.

  13. New routes to the synthesis of amylose-block-polystyrene rod-coil block copolymers

    NARCIS (Netherlands)

    Loos, Katja; Müller, Axel H.E.

    2002-01-01

    Hybrid block copolymers amylose-block-polystyrene were synthesized by covalent attachment of maltoheptaose derivatives to end-functionalized polystyrene and subsequent enzymatic grafting from polymerization. The maltoheptaose derivatives were attached by reductive amination or hydrosilation to amino

  14. Block-based image hashing with restricted blocking strategy for rotational robustness

    Science.gov (United States)

    Xiang, Shijun; Yang, Jianquan

    2012-12-01

    Image hashing is a potential solution for image content authentication (a desired image hashing algorithm should be robust to common image processing operations and various geometric distortions). In the literature, researchers pay more attention to block-based image hashing algorithms due to their robustness to common image processing operations (such as lossy compression, low-pass filtering, and additive noise). However, the block-based hashing strategies are sensitive to rotation processing operations. This indicates that the robustness of the block-based hashing methods against rotation operations is an important issue. Towards this direction, in this article we propose a restricted blocking strategy by investigating effect of two rotation operations on an image and its blocks in both theoretical and experimental ways. Furthermore, we apply the proposed blocking strategy for the recently reported non-negative matrix factorization (NMF) hashing. Experimental results have demonstrated the validity of the block-based hashing algorithms with restricted blocking strategy for rotation operations.

  15. Micellar aggregates of amylose-block-polystyrene rod-coil block copolymers in water and THF

    NARCIS (Netherlands)

    Loos, Katja; Böker, Alexander; Zettl, Heiko; Zhang, Mingfu; Krausch, Georg; Müller, Axel H.E.; Boker, A.; Zhang, A.F.

    2005-01-01

    Amylose-block-polystyrenes with various block copolymer compositions were investigated in water and in THF solution. Fluorescence correlation spectroscopy, dynamic light, scattering (DLS), and asymmetric flow field-flow fractionation with multiangle light scattering detection indicate the presence o

  16. Layer-by-layer nanoencapsulation of camptothecin with improved activity.

    Science.gov (United States)

    Parekh, Gaurav; Pattekari, Pravin; Joshi, Chaitanya; Shutava, Tatsiana; DeCoster, Mark; Levchenko, Tatyana; Torchilin, Vladimir; Lvov, Yuri

    2014-04-25

    160 nm nanocapsules containing up to 60% of camptothecin in the core and 7-8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-l-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell. PMID:24508806

  17. Doped Y.sub.2O.sub.3 buffer layers for laminated conductors

    Science.gov (United States)

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2007-08-21

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the metallic substrate, the biaxially textured buffer layer comprising Y.sub.2O.sub.3 and a dopant for blocking cation diffusion through the Y.sub.2O.sub.3, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  18. Erosion patterns on dissolving blocks

    Science.gov (United States)

    Courrech du Pont, Sylvain; Cohen, Caroline; Derr, Julien; Berhanu, Michael

    2016-04-01

    Patterns in nature are shaped under water flows and wind action, and the understanding of their morphodynamics goes through the identification of the physical mechanisms at play. When a dissoluble body is exposed to a water flow, typical patterns with scallop-like shapes may appear [1,2]. These shapes are observed on the walls of underground rivers or icebergs. We experimentally study the erosion of dissolving bodies made of salt, caramel or ice into water solutions without external flow. The dissolving mixture, which is created at the solid/liquid interface, undergoes a buoyancy-driven instability comparable to a Rayleigh-Bénard instability so that the dissolving front destabilizes into filaments. This mechanism yields to spatial variations of solute concentration and to differential dissolution of the dissolving block. We first observe longitudinal stripes with a well defined wavelength, which evolve towards chevrons and scallops that interact and move again the dissolving current. Thanks to a careful analysis of the competing physical mechanisms, we propose scaling laws, which account for the characteristic lengths and times of the early regime in experiments. The long-term evolution of patterns is understood qualitatively. A close related mechanism has been proposed to explain structures observed on the basal boundary of ice cover on brakish lakes [3] and we suggest that our experiments are analogous and explain the scallop-like patterns on iceberg walls. [1] P. Meakin and B. Jamtveit, Geological pattern formation by growth and dissolution in aqueous systems, Proc. R. Soc. A 466, 659-694 (2010). [2] P.N. Blumberg and R.L. Curl, Experimental and theoretical studies of dissolution roughness, J. Fluid Mech. 65, 735-751 (1974). [3] L. Solari and G. Parker, Morphodynamic modelling of the basal boundary of ice cover on brakish lakes, J.G.R. 118, 1432-1442 (2013).

  19. Round Gating for Low Energy Block Ciphers

    DEFF Research Database (Denmark)

    Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco;

    2016-01-01

    design techniques for implementing block ciphers in a low energy fashion. We concentrate on round based implementation and we discuss how gating, applied at round level can affect and improve the energy consumption of the most common lightweight block cipher currently used in the internet of things...

  20. Block Grants: Federal Data Collection Provisions.

    Science.gov (United States)

    General Accounting Office, Washington, DC. Div. of Human Resources.

    This fact sheet compares statutory data collection and reporting provisions of the federal education block grant (chapter 2 of the Education Consolidation and Improvement Act of 1981) with the nine other block grant programs funded in fiscal year 1986; data on statutory administrative cost limits are also provided. Each grant's legislation was…

  1. Block Gas Sol Unit in Haderslev

    DEFF Research Database (Denmark)

    Vejen, Niels Kristian

    2000-01-01

    Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark.......Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark....

  2. Improving massive experiments with threshold blocking.

    Science.gov (United States)

    Higgins, Michael J; Sävje, Fredrik; Sekhon, Jasjeet S

    2016-07-01

    Inferences from randomized experiments can be improved by blocking: assigning treatment in fixed proportions within groups of similar units. However, the use of the method is limited by the difficulty in deriving these groups. Current blocking methods are restricted to special cases or run in exponential time; are not sensitive to clustering of data points; and are often heuristic, providing an unsatisfactory solution in many common instances. We present an algorithm that implements a widely applicable class of blocking-threshold blocking-that solves these problems. Given a minimum required group size and a distance metric, we study the blocking problem of minimizing the maximum distance between any two units within the same group. We prove this is a nondeterministic polynomial-time hard problem and derive an approximation algorithm that yields a blocking where the maximum distance is guaranteed to be, at most, four times the optimal value. This algorithm runs in O(n log n) time with O(n) space complexity. This makes it, to our knowledge, the first blocking method with an ensured level of performance that works in massive experiments. Whereas many commonly used algorithms form pairs of units, our algorithm constructs the groups flexibly for any chosen minimum size. This facilitates complex experiments with several treatment arms and clustered data. A simulation study demonstrates the efficiency and efficacy of the algorithm; tens of millions of units can be blocked using a desktop computer in a few minutes. PMID:27382151

  3. Building blocks for embedded control systems

    NARCIS (Netherlands)

    Broenink, Jan F.; Hilderink, Gerald H.; Bakkers, André W.P.; Veen, Jean Pierre

    2000-01-01

    Developing embedded control systems using a building-block approach at all the parts enables an efficient and fast design process. Main reasons are the real plug-and-play capabilities of the blocks. Furthermore, due the simulatability of the designs, parts of the system can already be tested before

  4. C++ application development with Code::Blocks

    CERN Document Server

    Modak, Biplab Kumar

    2013-01-01

    This is a comprehensive tutorial with step-by-step instructions on how to develop applications with Code::Blocks.This book is for C++ developers who wish to use Code::Blocks to create applications with a consistent look and feel across multiple platforms. This book assumes that you are familiar with the basics of the C++ programming language.

  5. Young Children's Block Play and Mathematical Learning

    Science.gov (United States)

    Park, Boyoung; Chae, Jeong-Lim; Boyd, Barbara Foulks

    2008-01-01

    This qualitative study investigated young children's mathematical engagement in play with wooden unit blocks. Two boys, ages 6 and 7, were independently observed completing the task of filling outlined regions with the various sets of blocks. Three major mathematical actions were observed: categorizing geometric shapes, composing a larger shape…

  6. CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES

    NARCIS (Netherlands)

    Hilberer, A; Gill, R.E; Herrema, J.K; Malliaras, G.G; Wildeman, J.; Hadziioannou, G

    1995-01-01

    In this article we review results obtained in our laboratory on the design and study of new light-emitting polymers. We are interested in the synthesis and characterisation of block copolymers with regularly alternating conjugated and non conjugated sequences. The blocks giving rise to luminescence

  7. Programs for the calculi of blocks permeabilities

    International Nuclear Information System (INIS)

    This report studies the stochastic analysis of radionuclide transport. The permeability values of blocks are necessary to do a numeric model for the flux and transport problems in ground soils. The determination of block value by function on grill value is the objective of this program

  8. Light extraction block with curved surface

    Energy Technology Data Exchange (ETDEWEB)

    Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.

    2016-03-22

    Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.

  9. Transient non-autoimmune fetal heart block

    NARCIS (Netherlands)

    Breur, JMPJ; Oudijk, MA; Stoutenbeek, P; Visser, GHA; Meijboom, EJ

    2005-01-01

    Objectives: Fetal heart block is a rare and irreversible condition associated with structural heart defects or maternal autoantibodies (SS-A/Ro and SS-B/La) resulting in permanent damage of the atrioventricular (AV) node. This is the first report of 4 cases with a transient fetal heart block in stru

  10. PEO-related block copolymer surfactants

    DEFF Research Database (Denmark)

    Mortensen, K.

    2001-01-01

    Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems...

  11. Ultrasonographic evaluation of neck hematoma and block salvage after failed neurostimulation-guided interscalene block.

    Science.gov (United States)

    Howell, Stephen M; Unger, M W Todd; Colson, James D; Serafini, Mario

    2010-11-01

    Ultrasound-guided regional anesthetic techniques have shown some advantages over conventional paresthesia and neurostimulation techniques. We report the case of a neurostimulation-guided continuous interscalene block that would have ended in complication were it not for experience with ultrasound-guided regional anesthesia. Familiarity with ultrasound-guided block techniques permitted assessment of a neck hematoma during interscalene block and ultimately allowed successful peripheral nerve block.

  12. A Nonlinear Multi-Scale Interaction Model for Atmospheric Blocking: The Eddy-Blocking Matching Mechanism

    Science.gov (United States)

    Luo, Dehai; Cha, Jing; Zhong, Linhao; Dai, Aiguo

    2014-05-01

    In this paper, a nonlinear multi-scale interaction (NMI) model is used to propose an eddy-blocking matching (EBM) mechanism to account for how synoptic eddies reinforce or suppress a blocking flow. It is shown that the spatial structure of the eddy vorticity forcing (EVF) arising from upstream synoptic eddies determines whether an incipient block can grow into a meandering blocking flow through its interaction with the transient synoptic eddies from the west. Under certain conditions, the EVF exhibits a low-frequency oscillation on timescales of 2-3 weeks. During the EVF phase with a negative-over- positive dipole structure, a blocking event can be resonantly excited through the transport of eddy energy into the incipient block by the EVF. As the EVF changes into an opposite phase, the blocking decays. The NMI model produces life cycles of blocking events that resemble observations. Moreover, it is shown that the eddy north-south straining is a response of the eddies to a dipole- or Ω-type block. In our model, as in observations, two synoptic anticyclones (cyclones) can attract and merge with one another as the blocking intensifies, but only when the feedback of the blocking on the eddies is included. Thus, we attribute the eddy straining and associated vortex interaction to the feedback of the intensified blocking on synoptic eddies. The results illustrate the concomitant nature of the eddy deformation, whose role as a PV source for the blocking flow becomes important only during the mature stage of a block. Our EBM mechanism suggests that an incipient block flow is amplified (or suppressed) under certain conditions by the EVF coming from the upstream of the blocking region.

  13. A revisit of transthecal digital block and traditional digital block for anesthesia of the finger

    OpenAIRE

    Mohammad Dehghani; Arsalan Mahmoodian

    2007-01-01

    BACKGROUND: Finger injuries are very common and the majority can be treated under digital block anesthesia. Traditional digital block is one of the most commonly performed blocks by care providers in several medical fields. There is another less known method, transthecal (Pulley) block, in which local anesthesia is injected into the flexor tendon sheath.
    METHODS: A randomized clinical trial was performed to compare the tran...

  14. Fermion RG blocking transformations and IR structure

    CERN Document Server

    Cheng, X

    2011-01-01

    We explore fermion RG block-spinning transformations on the lattice with the aim of studying the IR structure of gauge theories and, in particular, the existence of IR fixed points for varying fermion content. In the case of light fermions the main concern and difficulty is ensuring locality of any adopted blocking scheme. We discuss the problem of constructing a local blocked fermion action in the background of arbitrary gauge fields. We then discuss the carrying out of accompanying gauge field blocking. In the presence of the blocked fermions implementation of MCRG is not straightforward. By adopting judicious approximations we arrive at an easily implementable approximate RG recursion scheme that allows quick, inexpensive estimates of the location of conformal windows for various groups and fermion representations. We apply this scheme to locate the conformal windows in the case of SU(2) and SU(3) gauge groups. Some of the reasons for the apparent efficacy of this and similar decimation schemes are discuss...

  15. Virasoro conformal blocks in closed form

    CERN Document Server

    Perlmutter, Eric

    2015-01-01

    Virasoro conformal blocks are fixed in principle by symmetry, but a closed-form expression is unknown in the general case. In this work, we provide three closed-form expansions for the four-point Virasoro blocks on the sphere, for arbitrary operator dimensions and central charge $c$. We do so by solving known recursion relations. One representation is a sum over hypergeometric global blocks, whose coefficients we provide at arbitrary level. Another is a sum over semiclassical Virasoro blocks obtained in the limit in which two external operator dimensions scale linearly with large $c$. In both cases, the $1/c$ expansion of the Virasoro blocks is easily extracted. We discuss applications of these expansions to entanglement and thermality in conformal field theories and particle scattering in three-dimensional quantum gravity.

  16. The undesirable effects of neuromuscular blocking drugs

    DEFF Research Database (Denmark)

    Claudius, C; Garvey, L H; Viby-Mogensen, J

    2009-01-01

    Neuromuscular blocking drugs are designed to bind to the nicotinic receptor at the neuromuscular junction. However, they also interact with other acetylcholine receptors in the body. Binding to these receptors causes adverse effects that vary with the specificity for the cholinergic receptor...... in question. Moreover, all neuromuscular blocking drugs may cause hypersensitivity reactions. Often the symptoms are mild and self-limiting but massive histamine release can cause systematic reactions with circulatory and respiratory symptoms and signs. At the end of anaesthesia, no residual effect...... of a neuromuscular blocking drug should be present. However, the huge variability in response to neuromuscular blocking drugs makes it impossible to predict which patient will suffer postoperative residual curarization. This article discusses the undesirable effects of the currently available neuromuscular blocking...

  17. Continuous peripheral nerve blocks in children.

    Science.gov (United States)

    Dadure, C; Capdevila, X

    2005-06-01

    In recent years, regional anaesthesia in children has generated increasing interest. Continuous peripheral nerve blocks have an important role in the anaesthetic arsenal, allowing effective, safe and prolonged postoperative pain management. Indications for continuous peripheral nerve blocks depend on benefits/risks analysis of each technique for each patient. The indications include surgery associated with intense postoperative pain, surgery requiring painful physical therapy, and complex regional pain syndrome. Continuous peripheral nerve blocks are usually performed under general anaesthesia or sedation, and require appropriate equipment in order to decrease the risk of nerve injury. New techniques, such as transcutaneous stimulation or ultrasound guidance, appear to facilitate nerve and plexus identification in paediatric patients. Nevertheless, continuous peripheral nerve block may mask compartment syndrome in certain surgical procedure or trauma. Finally, ropivacaine appears to be the best local anaesthetic for continuous peripheral nerve blocks in children, requiring low flow rate with low concentration of the local anaesthetic. PMID:15966500

  18. STUDY ON POLYSULFONE-POLYESTER BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    DING Youjun; QI Daquan

    1988-01-01

    Synthesis and characterization of a series of Polysulfone (PSF)-Polyester (PEs) block copolymers were studied.The degree of randomness (B) of these block copolymers was calculated from the intensities of their proton signals in 1H NMR spectra and lies in the region of 0 < B < 1. It was shown that the degree of randomness (B) and the average sequence length (L) in block copolymers were relatively dependent on the reaction conditions, various feed ratios and structure of diols.The phenomenon was observed, when the PSF-PEs block copolymers dissolved in different solvents they had different viscosities and molecular conformations.The PSF-PEs block copolymers had better solvent resistance than homo-polysulfone.

  19. A Parent's Guide to Imaginative Block Play: Why Blocks Are Still One of America's Favorite Toys.

    Science.gov (United States)

    T.C. Timber/Habermaass Corp., Skaneateles, NY.

    This brochure, developed by a manufacturer of wooden blocks and trains, offers advice on the selection and use of toy blocks with children. The guide asserts that blocks, while often thought of as the most simple of toys, have great strength as creativity builders. Topics discussed in the brochure include: "Why We Want Our Children to Play"; "Why…

  20. A note on "Block H-matrices and spectrum of block matrices"

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-zhou; HUANG Ze-jun

    2008-01-01

    In this paper, we make further discussions and improvements on the results presented in the previously published work "Block H-matrices and spectrum of block matrices". Furthermore, a new bound for eigenvalues of block matrices is given with examples to show advantages of the new result.

  1. Structural Evolution of Low-Molecular-Weight Poly(ethylene oxide)-block-polystyrene Diblock Copolymer Thin Film

    Science.gov (United States)

    Huang, Xiaohua

    2013-01-01

    The structural evolution of low-molecular-weight poly(ethylene oxide)-block-polystyrene (PEO-b-PS) diblock copolymer thin film with various initial film thicknesses on silicon substrate under thermal annealing was investigated by atomic force microscopy, optical microscopy, and contact angle measurement. At film thickness below half of the interlamellar spacing of the diblock copolymer (6.2 nm), the entire silicon is covered by a polymer brush with PEO blocks anchored on the Si substrate due to the substrate-induced effect. When the film is thicker than 6.2 nm, a dense polymer brush which is equal to half of an interlamellar layer was formed on the silicon, while the excess material dewet this layer to form droplets. The droplet surface was rich with PS block and the PEO block crystallized inside the bigger droplet to form spherulite. PMID:24302862

  2. Investigation on the influences of layer structure and nanoporosity of light scattering TiO2 layer in DSSC

    Science.gov (United States)

    Apriani, T.; Arsyad, W. S.; Wulandari, P.; Hidayat, R.

    2016-08-01

    Dye-sensitized solar cell (DSSC) is one of promising photovoltaic materials due to its simplicity in fabrication process and rich variety of possible sensitizer molecules. DSSC cell is commonly constructed of TiO2 layer as photoelectrode, dye as photosensitizer, electrolyte as redox mediator, and platinum layer as counter electrode. TiO2 layer is often constructed from different types of layers, such as blocking layer, transparent layer, microchannel or light scattering layer, which is made usually by successive layer-by-layer process. In this work, different TiO2 layers with different thickness and heat treatment were prepared and then used to build a complete sandwich-type DSSC. The characterization results show that the power conversion efficiency (PCE) is slightly reduced when using TiO2 layer with multiple scattering layers. This reduction is caused by an increase in the resistance from charge transport and charge transfer inside the mesoporous TiO2 layer, as revealed from the electrochemical impedance spectroscopy measurement results. Additional heat treatment introduced at the final step in the TiO2 layer preparation process, however, slightly improve the cell performance. Although this heat treatment does not produce significant change in porosity or pore size distribution of the TiO2 layer, it might be able to improve the contact between the TiO2 nanoparticles. The best PCE achieved in this work is about 5.3%, which was observed in the cell using TiO2 layer with one scattering layer and additional heat treatment.

  3. DYNAMIC BEHAVIOR OF TYRE TREAD BLOCK

    Directory of Open Access Journals (Sweden)

    K. Sridharan

    2012-01-01

    Full Text Available The Tyre tread pattern is the arrangement of blocks, grooves and voids, sipes and channels designed into the tread to enhance its grip on the road. Tread is the uppermost part of any tyre which contact into the road and it has its own performance towards mileage, traction, low noise and heat built up properties. It would be meaningful to conduct an extended analysis on the tyre tread blocks for its performance in static and dynamic condition to predict its behavior and wear of tread block in on-road condition. The Finite Element software Abaqus is used for the present analysis of the tread block and its behavior was studied on two different contact surfaces. The tread block is modeled in six different shapes and analyzed for is performance. The deformation stress strain characteristic of different blocks is studied which will be useful in deciding the contact behavior, friction and road grip. The regular shape/geometry has common behavior and the mixed type geometry shows a distinguished variation in the analysis. The dynamic stiffness and deformed shape was analyzed in this study and it has its own effect in tyre design. The tread block dynamics study by geometric shape would be vital in tread pattern optimization to enhance the traction, better hydroplaning and rolling resistance under all operating conditions.

  4. Circular block matching based video stabilization

    Science.gov (United States)

    Xu, Lidong; Fu, Fangwen; Lin, Xinggang

    2005-07-01

    Video sequences captured by handheld digital camera need to be stabilized to eliminate the tiresome effects caused by camera"s undesirable shake or jiggle. The key issue of video stabilization is to estimate the global motion parameters between two successive frames. In this paper, a novel circular block matching algorithm is proposed to estimate the global motion parameters. This algorithm can deal with not only translational motion but even large rotational motion. For an appointed circular block in current frame, a four-dimensional rotation invariant feature vector is firstly extracted from it and used to judge if it is an effective block. Then the rotation invariant features based circular block matching process is performed to find the best matching blocks in reference frame for those effective blocks. With the matching results of any two effective blocks, a two-dimensional motion model is constructed to produce one group of frame motion parameters. A statistical method is proposed to calculate the estimated global motion parameters with all groups of global motion parameters. Finally, using the estimated motion parameters as the initial values, an iteration algorithm is introduced to obtain the refined global motion parameters. The experimental results show that the proposed algorithm is excellent in stabilizing frames with even burst global translational and rotational motions.

  5. Inter-layer FEC decoded multi-layer video streaming

    OpenAIRE

    Huo, Yongkai; Zuo, Xin; Robert G. Maunder; Hanzo, L

    2012-01-01

    Layered video coding creates multiple layers of unequal importance, where the enhancement layers will be affected when the base layer is corrupted. In this treatise, a novel inter-layer FEC scheme is investigated, where the information of the base layer1 is incorporated into the systematic bits of the enhancement layers with the aid of an exclusive-OR operation. When the base layer can be recovered independently, the soft information of the enhancement layers can be deduced by flipping the si...

  6. Gaussian curvature analysis allows for automatic block placement in multi-block hexahedral meshing.

    Science.gov (United States)

    Ramme, Austin J; Shivanna, Kiran H; Magnotta, Vincent A; Grosland, Nicole M

    2011-10-01

    Musculoskeletal finite element analysis (FEA) has been essential to research in orthopaedic biomechanics. The generation of a volumetric mesh is often the most challenging step in a FEA. Hexahedral meshing tools that are based on a multi-block approach rely on the manual placement of building blocks for their mesh generation scheme. We hypothesise that Gaussian curvature analysis could be used to automatically develop a building block structure for multi-block hexahedral mesh generation. The Automated Building Block Algorithm incorporates principles from differential geometry, combinatorics, statistical analysis and computer science to automatically generate a building block structure to represent a given surface without prior information. We have applied this algorithm to 29 bones of varying geometries and successfully generated a usable mesh in all cases. This work represents a significant advancement in automating the definition of building blocks.

  7. Using Layer-Cake Geology to Illustrate Structural Topographic Relationships.

    Science.gov (United States)

    Wagner, John Robert

    1987-01-01

    Discusses some of the difficulties of visualizing underlying geologic structural patterns by using maps or wooden blocks. Suggests the use of a modified layer cake to show dipping beds, folds, faults and differential erosion, as well as the relationships of stream valleys to outcrop patterns. (TW)

  8. H-Seda: Partial Packet Recovery with Heterogeneous Block Sizes for Wireless Sensor Networks

    KAUST Repository

    Meer, Ammar M.

    2012-12-08

    Wireless sensor networks (WSN) have been largely used in various applications due to its ease of deployment and scalability. The throughput of such networks, however, suffers from high bit error rates mainly because of medium characteristics. Maximizing bandwidth utilization while maintaining low frame error rate has been an interesting problem. Frame fragmentation into small blocks with dedicated error detection codes per block can reduce the unnecessary retransmission of the correctly received blocks. The optimal block size, however, varies based on the wireless channel conditions. In addition, blocks within a frame can have different optimal sizes based on the variations on interference patterns. This thesis studies two dynamic partial packet recovery approaches experimentally over several interference intensities with various transmission-power levels. It also proposes a dynamic data link layer protocol: Hybrid Seda (H-Seda). H-Seda effectively addresses the challenges associated with dynamic partitioning of blocks while taking the observed error patterns into consideration. The design of H-Seda is discussed in details and compared to other previous approaches, namely Seda+ and Seda. The implementation of H-Seda shows substantial enhancements over fixed-size partial packet recovery protocols, achieving up to 2.5x improvement in throughput when the channel condition is noisy, while delay experienced decreases to only 14 % of the delay observed in Seda. On average, it shows 35% gain in goodput across all channel conditions used in our experiments. This significant improvement is due to the selective nature of H-Seda which minimizes retransmission overhead by selecting the appropriate number of blocks in each data frame. Additionally, H-Seda successfully reduces block overhead by 50% through removing block number field reaching to better performance when channel conditions are identical.

  9. Readiness for surgery after axillary block

    DEFF Research Database (Denmark)

    Koscielniak-Nielsen, Z J; Stens-Pedersen, H L; Lippert, F K

    1997-01-01

    We have assessed prospectively the time to readiness for surgery following axillary block (sum of block performance and latency times) in 80 patients. The brachial plexus was identified using a nerve stimulator, and anaesthetized with 45 mL of mepivacaine 1% with adrenaline 5 micrograms mL-1....... In group 1 (single injection) the whole volume of mepivacaine was injected after locating only one of the plexus nerves. In group 2 (multiple injections) at least three plexus nerves were located, and the volume of mepivacaine was divided between them. Sensory block was assessed by a blinded observer every...

  10. Theory of circuit block switch-off

    Directory of Open Access Journals (Sweden)

    S. Henzler

    2004-01-01

    Full Text Available Switching-off unused circuit blocks is a promising approach to supress static leakage currents in ultra deep sub-micron CMOS digital systems. Basic performance parameters of Circuit Block Switch-Off (CBSO schemes are defined and their dependence on basic circuit parameters is estimated. Therefore the design trade-off between strong leakage suppression in idle mode and adequate dynamic performance in active mode can be supported by simple analytic investigations. Additionally, a guideline for the estimation of the minimum time for which a block deactivation is useful is derived.

  11. Superintegrability of $d$-dimensional Conformal Blocks

    CERN Document Server

    Isachenkov, Mikhail

    2016-01-01

    We observe that conformal blocks of scalar 4-point functions in a $d$-dimensional conformal field theory can mapped to eigenfunctions of a 2-particle hyperbolic Calogero-Sutherland Hamiltonian. The latter describes two coupled P\\"oschl-Teller particles. Their interaction, whose strength depends smoothly on the dimension $d$, is known to be superintegrable. Our observation enables us to exploit the rich mathematical literature on Calogero-Sutherland models in deriving various results for conformal field theory. These include an explicit construction of conformal blocks in terms of Heckman-Opdam hypergeometric functions and a remarkable duality that relates the blocks of theories in different dimensions.

  12. Measurement of soil moisture using gypsum blocks

    DEFF Research Database (Denmark)

    Friis Dela, B.

    For the past 50 years, gypsum blocks have been used to determine soil moisture content. This report describes a method for calibrating gypsum blocks for soil moisture measurements. Moisture conditions inside a building are strongly influenced by the moisture conditions in the soil surrounding...... the building. Consequently, measuring the moisture of the surrounding soil is of great importance for detecting the source of moisture in a building. Up till now, information has been needed to carry out individual calibrations for the different types of gypsum blocks available on the market and to account...

  13. Micellization and Dynamics of a Block Copolymer

    DEFF Research Database (Denmark)

    Hvidt, Søren

    2006-01-01

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are industrially important copolymers often called Pluronics or Poloxamers. EPE copolymers form micelles with a core of P blocks and different micellar shapes depending on block length...... copolymer mixtures, and evidence in favor of a multi-equilibria unimer-micelle model will be presented. Results obtained by liquid chromatographic methods will be shown and it will be demonstrated that commercial EPE copolymers are inhomogeneous at several levels and many of their unusual properties reflect...

  14. Low-dislocation-density epitatial layers grown by defect filtering by self-assembled layers of spheres

    Science.gov (United States)

    Wang, George T.; Li, Qiming

    2013-04-23

    A method for growing low-dislocation-density material atop a layer of the material with an initially higher dislocation density using a monolayer of spheroidal particles to bend and redirect or directly block vertically propagating threading dislocations, thereby enabling growth and coalescence to form a very-low-dislocation-density surface of the material, and the structures made by this method.

  15. Fracture Mechanisms of Layer-By-Layer Polyurethane/Poly(Acrylic Acid) Nanocomposite

    Science.gov (United States)

    Kheng, Eugene R.

    A layer-by-layer(LBL) manufactured material is examined in detail in this thesis. Improvements are made to the method of its manufacture. Efforts are made to understand its fracture mechanisms and take advantage of these fracture mechanisms in the absorption of impact energy. A novel series of experiments has been performed on LBL manufactured thin films to demonstrate their unique fracture mechanisms. Polyurethane/Poly(Acrylic Acid) (PU/PAA) and PU/PAA/(PU/Clay)5 nanocomposite films readily undergo Interlaminar mode II fracture, because of the relatively weak elctrostatic bonds between monolayers. Tensile tests performed while under observation by a scanning electron microscope demonstrate the tendency of these nanocomposite films to undergo interlaminar mode II fracture even when loads are applied in the plane of nanocomposite film. It is concluded that these mechanisms of energy dissipation are responsible for the enhanced toughness of these films when used as layers between glass blocks in the prevention of impact damage to the glass. A novel automated manufacturing facility has been designed and built to deposit large sheets of Layer-by-Layer nanocomposite film. These large sheets are incorporated into a borosillicate glass composite in order to compare the ballistic characteristics of LBL PU based nanocomposite films to a single cast layer of polyurethane. It is demonstrated that shear fracture is the mode of failure in the blocks containing the nanocomposite film. The shear fracture surface in the nanocomposite after it has undergone a ballistic impact is characterized. Additional experiments are performed to characterize the interlaminar fracture stresses and toughnesses of the nanocomposite LBL layers, to assist in the implementation of a numerical crack band model that describes the nanocomposite film. The computational model predicts the failure of the ballistic nanocomposite samples, and the predicted V50 velocity is found to be in good agreement with

  16. Extended mode in blocked impurity band detectors for terahertz radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Liao, K. S.; Li, N.; Wang, C.; Li, L.; Jing, Y. L.; Wen, J.; Li, M. Y.; Wang, H.; Zhou, X. H., E-mail: xhzhou@mail.sitp.ac.cn; Li, Z. F.; Lu, W., E-mail: luwei@mail.sitp.ac.cn [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2014-10-06

    We demonstrate the existence of an interfacial barrier in blocked impurity band (BIB) detectors using temperature-dependent dark current and corresponding theoretical calculations. Considering the effects of the interfacial barrier, the calculated photoresponse is in good agreement with the experimental results. A dual-excitation model, including the direct excitation over the full barrier and excitation to the band minimum with subsequent tunneling into the blocking layer, is proposed to quantitatively explain the observed photoresponse extension. A concept of extended-mode detection is developed to suggest the option for some selective photoresponse in the terahertz region and open the possibility of extending BIB photoresponse to lower frequency.

  17. Evaluation of Environmental and Hydraulic Performance of Bio-Composite Revetment Blocks

    Directory of Open Access Journals (Sweden)

    Thamer A.  Ahmeed

    2006-01-01

    Full Text Available It is necessary to develop a concrete revetment block which can cater for environment and at the same time it will be effective in protecting river banks (stabilize the slope of banks from scouring during flood. In the present study, the environmental and hydraulic performance of the proposed revetment block was evaluated through laboratory and field tests. The tested revetment block is called bio-composite because it is composed of concrete, plastic mesh and biological material (coconut husk. The dimensions of the bio-composite revetment block are 400 mm x 400 mm x 100 mm (length x width x thickness and has a central opening with a dimensions of 280 mm x 140 mm that has a 10 mm layer of coconut husks protected by two layers of plastic mesh. The coconut husk was selected based on laboratory experiments. The experiments showed that the coconut husk is a good media for grass growth and it allows faster growth of grass compared with other tested types of biological wastes (sugar cane husk and oil palm husk. Field tests were conducted on a selected stream which is located at the Universiti Putra Malaysia, Selangor, Malaysia. The stream banks were protected from scouring by using the bio-composite blocks and monitoring after installation revealed that rate of grass growth was 15% per week. However, it was found that the rate of grass growth is depends on the slope of stream banks. This confirms that the proposed bio-composite block is friendly to the environment and can give a good aesthetic appearance. For a given water depth, hydraulic tests showed that the value of Manning coefficient of roughness for the bio-composite revetment blocks depends mainly on the rate of grass growth. The values of Manning coefficient roughness for the stream were found to range from 0.031 to 0.055.

  18. Hydroplaning of subaqueous debris flows and glide blocks: Analytical solutions and discussion

    Science.gov (United States)

    Harbitz, Carl B.; Parker, Gary; ElverhøI, Anders; Marr, Jeffrey G.; Mohrig, David; Harff, Peter A.

    2003-07-01

    Subaqueous debris flows often attain significantly higher velocities and longer run-out distances than their subaerial counterparts in spite of increased viscous drag and reduced effective gravity due to buoyancy. Recent experimental research suggests that a basal lubricating layer of water associated with hydroplaning decouples the sediments from the bed, resulting in a dramatic reduction of the basal shear stress. Hydroplaning thus provides an explanation for these observations. The conditions for onset of hydroplaning are discussed in terms of critical densimetric Froude number. The stress reduction due to a lubricating layer of water or mud slurry is studied via equilibrium solutions for a two-layer Couette flow. The calculations reveal that the stresses in both the low-viscosity lubricating layer and the high-viscosity deforming deposits below it are substantially reduced. The principles of laminar boundary layers are used to develop an equilibrium solution for the steady motion of a hydroplaning debris glide block. This adjusted version of lubrication theory properly accounts for hydroplaning associated with a dynamic pressure generated at the head of the block. Example calculations at both laboratory and field scale support the experimental results of reduced bed friction, limited erosion, sediment rheology independence, and high velocities. The results also reveal the possibility for a net up-slope discharge in the lubricating layer.

  19. Physical layer approaches for securing wireless communication systems

    CERN Document Server

    Wen, Hong

    2013-01-01

    This book surveys the outstanding work of physical-layer (PHY) security, including  the recent achievements of confidentiality and authentication for wireless communication systems by channel identification. A practical approach to building unconditional confidentiality for Wireless Communication security by feedback and error correcting code is introduced and a framework of PHY security based on space time block code (STBC) MIMO system is demonstrated.  Also discussed is a scheme which combines cryptographic techniques implemented in the higher layer with the physical layer security approach

  20. Algorithms for Finding the Inverses of Factor Block Circulant Matrices

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, algorithms for finding the inverse of a factor block circulant matrix,a factor block retrocirculant matrix and partitioned matrix with factor block circulant blocks over the complex field are presented respectively. In addition, two algorithms for the inverse of a factor block circulant matrix over the quaternion division algebra are proposed.

  1. Block Tridiagonal Matrices in Electronic Structure Calculations

    DEFF Research Database (Denmark)

    Petersen, Dan Erik

    is developed and compared to standard Gaussian elimination, where it is shown to be qualitatively quicker for the task of determining the block tridiagonal portion of the Green’s function matrix. The Sweep algorithm is then parallelized via a straightforward approach in order to enable moderate speedup...... and memory distribution. The well known block cyclic reduction algorithm first developed by Gene Golub is then presented and analyzed for further expanding our parallel options, and finally a new hybrid method that combines block cyclic reduction and a form of Schur complement calculation is introduced...... in the Landauer–Büttiker ballistic transport regime. These calculations concentrate on determining the so– called Green’s function matrix, or portions thereof, which is the inverse of a block tridiagonal general complex matrix. To this end, a sequential algorithm based on Gaussian elimination named Sweeps...

  2. Functionalization of Block Copolymer Vesicle Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang Meier

    2011-01-01

    Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.

  3. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential...... applications as, e.g., membranes for separation and purification, templates for nanostructured materials, sensors, substrates for catalysis, low dielectric constant materials, photonic materials, and depots for controlled drug delivery. The development of nanoporous polymers with well controlled pore wall...... functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed...

  4. Quantum Integrable Systems from Conformal Blocks

    CERN Document Server

    Chen, Heng-Yu

    2016-01-01

    In this note, we extend the striking connections between quantum integrable systems and conformal blocks recently found in http://arxiv.org/abs/1602.01858 in several directions. First, we explicitly demonstrate that the action of quartic conformal Casimir operator on general d-dimensional scalar conformal blocks, can be expressed in terms of certain combinations of commuting integrals of motions of the two particle hyperbolic BC2 Calogero-Sutherland system. The permutation and reflection properties of the underlying Dunkl operators play crucial roles in establishing such a connection. Next, we show that the scalar superconformal blocks in SCFTs with four and eight supercharges and suitable chirality constraints can also be identified with the eigenfunctions of the same Calogero-Sutherland system, this demonstrates the universality of such a connection. Finally, we observe that the so-called "seed" conformal blocks for constructing four point functions for operators with arbitrary space-time spins in four dime...

  5. Genetics Home Reference: progressive familial heart block

    Science.gov (United States)

    Skip to main content Your Guide to Understanding Genetic Conditions Enable Javascript for addthis links to activate. ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions progressive familial heart block progressive ...

  6. Deformations of one-dimensional block media

    CERN Document Server

    Aleksandrova, Nadezhda

    2014-01-01

    The paper gives a description of wave propagation in discrete-periodic one-dimensional media with block structure. For one-dimensional problems mathematical models are proposed that describe block structures in the form of a mass chain or bars connected by elastic springs and viscous dampers. For these models, the numerical calculations of the parameters of perturbations are obtained as well as asymptotic solutions at large time since the beginning of pulse action. The numerical calculations and analytical solutions are compared.

  7. Investigating Mortality Uncertainty Using the Block Bootstrap

    Directory of Open Access Journals (Sweden)

    Xiaoming Liu

    2010-01-01

    Full Text Available This paper proposes a block bootstrap method for measuring mortality risk under the Lee-Carter model framework. In order to take account of all sources of risk (the process risk, the parameter risk, and the model risk properly, a block bootstrap is needed to cope with the spatial dependence found in the residuals. As a result, the prediction intervals we obtain for life expectancy are more accurate than the ones obtained from other similar methods.

  8. Theory of circuit block switch-off

    OpenAIRE

    S. Henzler; J. Berthold; G. Georgakos; Schmitt-Landsiedel, D.

    2005-01-01

    Switching-off unused circuit blocks is a promising approach to supress static leakage currents in ultra deep sub-micron CMOS digital systems. Basic performance parameters of Circuit Block Switch-Off (CBSO) schemes are defined and their dependence on basic circuit parameters is estimated. Therefore the design trade-off between strong leakage suppression in idle mode and adequate dynamic performance in active mode can be supported by simple analytic investigations. Additionally, a guideline for...

  9. Latent Block Model for Contingency Table

    OpenAIRE

    Govaert, Gérard; Nadif, Mohamed

    2010-01-01

    Although many clustering procedures aim to construct an optimal partition of objects or, sometimes, variables, there are other methods, called block clustering methods, which simultaneously consider the two sets and organize the data into homogeneous blocks. This kind of method has practical importance in a wide variety of applications such as text and market basket data analysis. Typically, the data that arise in these applications are arranged as a two-way contingency table. Using Poisson d...

  10. Building-block selectivity of polyketide synthases.

    Science.gov (United States)

    Liou, Grace F; Khosla, Chaitan

    2003-04-01

    For the past decade, polyketide synthases have presented an exciting paradigm for the controlled manipulation of complex natural product structure. These multifunctional enzymes catalyze the biosynthesis of polyketide natural products by stepwise condensation and modification of metabolically derived building blocks. In particular, regioselective modification of polyketide structure is possible by alterations in either intracellular acyl-CoA pools or, more commonly, by manipulation of acyl transferases that act as the primary gatekeepers for building blocks.

  11. Investigating Mortality Uncertainty Using the Block Bootstrap

    OpenAIRE

    Xiaoming Liu; W. John Braun

    2010-01-01

    This paper proposes a block bootstrap method for measuring mortality risk under the Lee-Carter model framework. In order to take account of all sources of risk (the process risk, the parameter risk, and the model risk) properly, a block bootstrap is needed to cope with the spatial dependence found in the residuals. As a result, the prediction intervals we obtain for life expectancy are more accurate than the ones obtained from other similar methods.

  12. Theoretical comparisons of block bootstrap methods

    OpenAIRE

    Lahiri, S. N.

    1999-01-01

    In this paper, we compare the asymptotic behavior of some common block bootstrap methods based on nonrandom as well as random block lengths. It is shown that, asymptotically, bootstrap estimators derived using any of the methods considered in the paper have the same amount of bias to the first order. However, the variances of these bootstrap estimators may be different even in the first order. Expansions for the bias, the variance and the mean-squared error of different bloc...

  13. Paravertebral block: review of the literature

    OpenAIRE

    Karaman Ilić, Maja; NESEK ADAM, VIŠNJA; MATOLIĆ, MARTINA; Kogler, Jana; Butković, Diana

    2015-01-01

    Background: Paravertebral Block (PVB) is an established regional anesthetic technique. It is technically easy to perform and is being used increasingly for intra-operative and post-operative analgesia. This popularity is mainly due to the ease of the technique and fewer complications. Materials and Methods: This is quantitative systematic review of literature database with the aim to assess the efficacy and safety of Paravertebral block in thoracic, abdominal and breast surgery. Resul...

  14. Determining Block Detector Positions for PET Scanners

    OpenAIRE

    Pierce, Larry; Miyaoka, Robert; Lewellen, Tom; Alessio, Adam; Kinahan, Paul

    2009-01-01

    We present an algorithm for accurate localization of block detectors in a positron emission tomography (PET) scanner. Accurate reconstruction of PET images requires precise knowledge of the physical position and orientation of the detectors. However, in some systems, block detector positioning and orientation can have relatively large tolerances, leading to implicit errors in the coincidence line-of-response (LOR) positioning. To compensate we utilize a rotating point source phantom where the...

  15. Permutations with Ascending and Descending Blocks

    CERN Document Server

    Steinhardt, Jacob

    2009-01-01

    We investigate permutations in terms of their cycle structure and descent set. To do this, we generalize the classical bijection of Gessel and Reutenauer to deal with permutations that have some ascending and some descending blocks. We then provide the first bijective proofs of some known results. We also solve some problems posed in [3] by Eriksen, Freij, and Wastlund, who study derangements that descend in blocks of prescribed lengths.

  16. Building blocks of e-commerce

    Indian Academy of Sciences (India)

    V Rajaraman

    2005-04-01

    This article examines the architecture of e-commerce as a set of layers, each supporting the one above it. The layers have clean interfaces, that is, they can be designed independently. We present an architecture with six layers. The lowest layer consists of a physical communication network such as local area network or public switched telephone networks. The next higher layer is the logical layer which describes the protocol used to interconnect communication systems to create internet, intranet and extranet. The services provided over the internet infrastructure, namely, e-mail, world wide web etc., are described in what is called network services layer. It is essential to ensure security of messages, documents etc., which are transmitted using network services. The messaging layer is thus concerned with encryption methods, both private and public key encryption and their applications. We call the layer above this the middleman service, which is concerned with valueadded services offered by intermediaries to enable payment for services received, certify digital signatures, safely transmit documents and provide information on behalf of companies. The topmost layer is the application layer which users see. The major applications are customer-to-business (C2B) e-commerce, business-tobusiness (B2B) e-commerce, customer-to-consumer (C2C) e-commerce etc. We briefly explain these modes.

  17. Interrogating the superconductor Ca10(Pt4As8)(Fe2‑xPtxAs2)5 Layer-by-layer

    Science.gov (United States)

    Kim, Jisun; Nam, Hyoungdo; Li, Guorong; Karki, A. B.; Wang, Zhen; Zhu, Yimei; Shih, Chih-Kang; Zhang, Jiandi; Jin, Rongying; Plummer, E. W.

    2016-10-01

    Ever since the discovery of high-Tc superconductivity in layered cuprates, the roles that individual layers play have been debated, due to difficulty in layer-by-layer characterization. While there is similar challenge in many Fe-based layered superconductors, the newly-discovered Ca10(Pt4As8)(Fe2As2)5 provides opportunities to explore superconductivity layer by layer, because it contains both superconducting building blocks (Fe2As2 layers) and intermediate Pt4As8 layers. Cleaving a single crystal under ultra-high vacuum results in multiple terminations: an ordered Pt4As8 layer, two reconstructed Ca layers on the top of a Pt4As8 layer, and disordered Ca layer on the top of Fe2As2 layer. The electronic properties of individual layers are studied using scanning tunneling microscopy/spectroscopy (STM/S), which reveals different spectra for each surface. Remarkably superconducting coherence peaks are seen only on the ordered Ca/Pt4As8 layer. Our results indicate that an ordered structure with proper charge balance is required in order to preserve superconductivity.

  18. Dietary cholesterol modulates pathogen blocking by Wolbachia.

    Directory of Open Access Journals (Sweden)

    Eric P Caragata

    Full Text Available The bacterial endosymbiont Wolbachia pipientis protects its hosts from a range of pathogens by limiting their ability to form infections inside the insect. This "pathogen blocking" could be explained by innate immune priming by the symbiont, competition for host-derived resources between pathogens and Wolbachia, or the direct modification of the cell or cellular environment by Wolbachia. Recent comparative work in Drosophila and the mosquito Aedes aegypti has shown that an immune response is not required for pathogen blocking, implying that there must be an additional component to the mechanism. Here we have examined the involvement of cholesterol in pathogen blocking using a system of dietary manipulation in Drosophila melanogaster in combination with challenge by Drosophila C virus (DCV, a common fly pathogen. We observed that flies reared on cholesterol-enriched diets infected with the Wolbachia strains wMelPop and wMelCS exhibited reduced pathogen blocking, with viral-induced mortality occurring 2-5 days earlier than flies reared on Standard diet. This shift toward greater virulence in the presence of cholesterol also corresponded to higher viral copy numbers in the host. Interestingly, an increase in dietary cholesterol did not have an effect on Wolbachia density except in one case, but this did not directly affect the strength of pathogen blocking. Our results indicate that host cholesterol levels are involved with the ability of Wolbachia-infected flies to resist DCV infections, suggesting that cholesterol contributes to the underlying mechanism of pathogen blocking.

  19. MIBSA: Multi Interacting Blocks for Slope Analysis

    Science.gov (United States)

    Dattola, Giuseppe; Crosta, Giovanni; Castellanza, Riccardo; di Prisco, Claudio

    2016-04-01

    As it is well known, the slope instabilities have very important consequences in terms of human lives and activities. So predicting the evolution in time and space of slope mass movements becomes fundamental. This is even more relevant when we consider that the triggering mechanisms are a rising ground water level and the occurrence of earthquakes. Therefore, seasonal rainfall has a direct influence on the triggering of large rock and earthslide with a composite failure surface and causing differential behaviors within the sliding mass. In this contribution, a model describing the slope mass by means of an array of blocks that move on a prefixed failure surface, is defined. A shear band located at the base of each block, whose behavior is modelled via a viscous plastic model based on the Perzyna's approach, controls the slip velocity of the block. The motion of the blocks is obtained by solving the second balance equation in which the normal and tangential interaction forces are obtained by a specific interaction model. The model has been implemented in an original code and it is used to perform a parametric analysis that describes the effects of block interactions under a transient ground water oscillation. The numerical results confirm that the normal and tangential interactions between blocks can inhibit or induce the slope movements. The model is tested against some real case studies. This model is under development to add the dynamic effects generated by earthquake shaking.

  20. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira

    2016-03-22

    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  1. Boosting Water Oxidation Layer-by-Layer

    OpenAIRE

    Hidalgo Acosta, Jonnathan Cesar; Scanlon, Micheal; Mendez, Manuel A.; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert

    2016-01-01

    Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and ...

  2. Building biomedical materials layer-by-layer

    Directory of Open Access Journals (Sweden)

    Paula T. Hammond

    2012-05-01

    Full Text Available In this materials perspective, the promise of water based layer-by-layer (LbL assembly as a means of generating drug-releasing surfaces for biomedical applications, from small molecule therapeutics to biologic drugs and nucleic acids, is examined. Specific advantages of the use of LbL assembly versus traditional polymeric blend encapsulation are discussed. Examples are provided to present potential new directions. Translational opportunities are discussed to examine the impact and potential for true biomedical translation using rapid assembly methods, and applications are discussed with high need and medical return.

  3. Catechol-based layer-by-layer assembly of composite coatings: a versatile platform to hierarchical nano-materials.

    Science.gov (United States)

    Wang, C X; Braendle, A; Menyo, M S; Pester, C W; Perl, E E; Arias, I; Hawker, C J; Klinger, D

    2015-08-21

    Inspired by the marine mussel's ability to adhere to surfaces underwater, an aqueous catechol-based dip coating platform was developed. Using a catechol-functionalized polyacrylamide binder in combination with inorganic nanoparticles enables the facile fabrication of robust composite coatings via a layer-by-layer process. This modular assembly of well-defined building blocks provides a versatile alternative to electrostatic driven approaches with layer thickness and refractive indices being readily tunable. The platform nature of this approach enables the fabrication of hierarchically ordered nano-materials such as Bragg stacks.

  4. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  5. Layering in Provenance Systems

    OpenAIRE

    Seltzer, Margo I.; Muniswamy-Reddy, Kiran-Kumar; Braun, Uri Jacob; Holland, David A.; MACKO Peter; Maclean, Diana; Margo, Daniel Wyatt; Smogor, Robin

    2009-01-01

    Digital provenance describes the ancestry or history of a digital object. Most existing provenance systems, however, operate at only one level of abstraction: the sys- tem call layer, a workflow specification, or the high-level constructs of a particular application. The provenance collectable in each of these layers is different, and all of it can be important. Single-layer systems fail to account for the different levels of abstraction at which users need to reason about their data and proc...

  6. Intra-His bundle block in 2:1 atrioventricular block

    Institute of Scientific and Technical Information of China (English)

    Seung; Pyo; Hong; Yon; Woong; Park; Young; Soo; Lee

    2015-01-01

    Intra-hisian atrioventricular(AV) block is not a common phenomenon, but it is important for the development of advanced or complete AV block. We observed a 77-yearold female patient with the 2:1 AV block due to an intrahisian block. In this case we tried to detect the block site, but an alternating pattern of the AH conduction was noted on the His-electrogram in the electrophysiological study(EPS). The cause of the confusing finding might have been the instability of the catheter to record a His potential. We could detect a splitting of the Hiselectrogram with an intra-hisian block after minimal manipulation of the catheter. The authors’ observations suggest that catheter stability is important for a precise recording in the EPS and radiofrequency catheter ablation procedure.

  7. The Early Paleozoic paleogeography of the North China block and the other major blocks of China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With the summarization of the Early Paleozoic paleomagnetic data recently obtained from the three major blocks of China, the Early Paleozoic (I.e. Cambrian and Ordovician) paleogeographic positions of the North China, South China and Tarim blocks were discussed in detail. The North China, South China and Tarim blocks were inferred to be located adjacent to East Gondwana in low latitudes of the Southern Hemisphere during the Early Cambrian. During the Early-Middle Ordovician, the South China and Tarim blocks were also located in low latitudes of the Southern Hemisphere with some affinities of the Gondwanaland, whereas the North China block may have episodically separated from the Gondwanaland, and might be sited close to the North America and Siberia. The reestablished paleogeographic configurations are in agreement with the studies on the biogeography, paleoclimate and sedimental facies of the North China and South China blocks.

  8. A Method for Detecting and Blocking Instant Messaging Software

    Directory of Open Access Journals (Sweden)

    Hao Zhang

    2013-10-01

    Full Text Available Instant messaging software, as a convenient network communication tool, is becoming more and more popular. At the same time, it also brings risks in security of local area network (LAN. Through studying in typical instant messaging software and detected by the combination of misuse detection and protocol analysis, an architecture of detecting and blocking mechanism of instant messaging software is proposed in this paper and its prototype system is achieved on Windows platform. This new system effectively solves the problems that the efficiency of traditional firewall application layer data filtering is low and the firewall cannot dynamically adjust the filtering rules, providing a good application value for the protection of the security of local area network.  

  9. Liquid Metallic Hydrogen: A Building Block for the Liquid Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2011-07-01

    Full Text Available Liquid metallic hydrogen provides a compelling material for constructing a condensed matter model of the Sun and the photosphere. Like diamond, metallic hydrogen might have the potential to be a metastable substance requiring high pressures for forma- tion. Once created, it would remain stable even at lower pressures. The metallic form of hydrogen was initially conceived in 1935 by Eugene Wigner and Hillard B. Huntington who indirectly anticipated its elevated critical temperature for liquefaction (Wigner E. and Huntington H.B. On the possibility of a metallic modification of hydro- gen. J. Chem. Phys. , 1935, v.3, 764–770. At that time, solid metallic hydrogen was hypothesized to exist as a body centered cubic, although a more energetically accessible layered graphite-like lattice was also envisioned. Relative to solar emission, this struc- tural resemblance between graphite and layered metallic hydrogen should not be easily dismissed. In the laboratory, metallic hydrogen remains an elusive material. However, given the extensive observational evidence for a condensed Sun composed primarily of hydrogen, it is appropriate to consider metallic hydrogen as a solar building block. It is anticipated that solar liquid metallic hydrogen should possess at least some layered order. Since layered liquid metallic hydrogen would be essentially incompressible, its invocation as a solar constituent brings into question much of current stellar physics. The central proof of a liquid state remains the thermal spectrum of the Sun itself. Its proper understanding brings together all the great forces which shaped modern physics. Although other proofs exist for a liquid photosphere, our focus remains solidly on the generation of this light.

  10. Rheological and Mechanical behaviour of Block copolymers, Multigraft copolymers and Block copolymer Nanocomposites

    OpenAIRE

    Thunga, Mahendra

    2009-01-01

    Block copolymers are commercially significant and fundamentally interesting class of polymeric materials. The ability to undergo interfacial thermodynamics-controlled microphase separation from a completely disordered state in the melt to a specifically defined ordered structure through self-organization makes the block copolymers based materials unique. Block copolymer are strongly replacing many of the commercially available polymers due to their unique microstructure and properties. The mo...

  11. Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty

    DEFF Research Database (Denmark)

    Jaeger, Pia; Zaric, Dusanka; Fomsgaard, Jonna Storm;

    2013-01-01

    Femoral nerve block (FNB), a commonly used postoperative pain treatment after total knee arthroplasty (TKA), reduces quadriceps muscle strength essential for mobilization. In contrast, adductor canal block (ACB) is predominately a sensory nerve block. We hypothesized that ACB preserves quadriceps...... muscle strength as compared with FNB (primary end point) in patients after TKA. Secondary end points were effects on morphine consumption, pain, adductor muscle strength, morphine-related complications, and mobilization ability....

  12. Stability of the perforated layer (PL) phase in diblock copolymer melts

    DEFF Research Database (Denmark)

    Hajduk, Damian A; Takenouchi, Hiroshi; Hillmyer, Marc A;

    1997-01-01

    We reexamine the stability of hexagonally modulated layer (HML) and hexagonally perforated layer (HPL) morphologies in a number of block copolymer systems of low to moderate molecular weight. Using small-angle X-ray scattering and dynamic mechanical spectroscopy, we show that these structures are...

  13. Zinc Composite Layers, Incorporating Polymeric Nano-aggregates: Surface Analysis and Electrochemical Behavior

    NARCIS (Netherlands)

    Koleva, D.A.; Zhang, X.; Petrov, P.; Boshkov, N.; Van Breugel, K.; De Wit, J.H.W.; Mol, J.M.C.; Tsvetkova, N.

    2008-01-01

    This study reports on a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers in 5% NaCl solution. The metallic matrix of the ZnC layers incorporates nano-sized, stabilized polymeric aggregates, formed from the amphiphilic tri-block co-polymer

  14. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    KAUST Repository

    Yu, Haizhou

    2015-10-16

    Recently two quite different types of “nano-containers” have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles (“filomicelles”) on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected.

  15. Real-time ultrasound-guided comparison of adductor canal block and psoas compartment block combined with sciatic nerve block in laparoscopic knee surgeries

    OpenAIRE

    Messeha, Medhat M.

    2016-01-01

    Background: Lumbar plexus block, combined with a sciatic nerve block, is an effective locoregional anesthetic technique for analgesia and anesthesia of the lower extremity. The aim of this study was to compare the clinical results outcome of the adductor canal block versus the psoas compartment block combined with sciatic nerve block using real time ultrasound guidance in patients undergoing elective laparoscopic knee surgeries. Patients and Methods: Ninety patients who were undergoing electi...

  16. Synthesis of polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile triblock copolymers via RAFT polymerization

    Institute of Scientific and Technical Information of China (English)

    Zheng Yue; Deng Xu Wang; Jing Quan Liu; Jie Zhang; Sheng Yu Feng

    2012-01-01

    A new A-B-A type of block copolymers,polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile (PAN-b-PDMS-b-PAN),which comprises two polymer blocks of different polarities and compatibilities,were synthesized for the first time via reversible addition-fragmentation chain transfer polymerization.Reaction kinetics was investigated.PAN-b-PDMS-b-PAN films were prepared by spin-coating on glass chips.Significant order on the film surface morphologies was observed.(C) 2012 Jie Zhang.Published by Elsevier B.V.on behalf of Chinese Chemical Society.All rights reserved.

  17. A comparison of four different block bootstrap methods

    OpenAIRE

    Boris Radovanov; Aleksandra Marcikić

    2014-01-01

    The paper contains a description of four different block bootstrap methods, i.e., non-overlapping block bootstrap, overlapping block bootstrap (moving block bootstrap), stationary block bootstrap and subsampling. Furthermore, the basic goal of this paper is to quantify relative efficiency of each mentioned block bootstrap procedure and then to compare those methods. To achieve the goal, we measure mean square errors of estimation variance returns. The returns are calculated from 1250 daily ob...

  18. Randomized Block Subgradient Methods for Convex Nonsmooth and Stochastic Optimization

    OpenAIRE

    Deng, Qi; Lan, Guanghui; Rangarajan, Anand

    2015-01-01

    Block coordinate descent methods and stochastic subgradient methods have been extensively studied in optimization and machine learning. By combining randomized block sampling with stochastic subgradient methods based on dual averaging, we present stochastic block dual averaging (SBDA)---a novel class of block subgradient methods for convex nonsmooth and stochastic optimization. SBDA requires only a block of subgradients and updates blocks of variables and hence has significantly lower iterati...

  19. [Effectiveness of sympathetic block using various technics].

    Science.gov (United States)

    Weissenberg, W

    1987-07-01

    Blocking of sympathetic conduction aims at permanent or temporary elimination of those pain pathways conducted by the sympathetic nervous system. In order to provide an objective evaluation of sufficient blocking effect, earlier inquiries referred to parameters such as: (1) observation of clinical signs such as Horner's syndrome, Guttman's sign, anhidrosis, extended venous filling; (2) difference in skin temperature of at least 1.5 degrees C between blocked and unblocked side; (3) increase in amplitude of the pulse wave; and (4) depression of the psychogalvanic reflex (PGR) on the blocked side (Fig. 1). In clinical practice, these control parameters are effective because they are time-saving, technically simple, and highly evidential. Further parameters for evaluating sympathetic blockade are examination of hydrosis by means of color indicators such as bromocresol and ninhydrin, oscillometry, and plethysmography. The effectiveness of sympathetic blockade after stellate ganglion and sympathetic trunk blocks has been verified by various authors. In a clinical study, 16 patients were divided into four groups in order to test the effectiveness of sympathetic blockade after spinal anesthesia with 3 ml 0.75% bupivacaine (group I) and 4 ml 0.75% bupivacaine (group II) and after peridural anesthesia with 15 ml 0.75% bupivacaine (group III) and 20 ml 0.75% bupivacaine (group IV) by means of temperature difference, response of pulse wave amplitude and PGR between blocked lower and unblocked upper extremity, and sensory levels of block. The patients were classified as ASA I and II; their ages varied from 20 to 63 years.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Ultrasound guided TAP block versus ultrasound guided caudal block for pain relief in children undergoing lower abdominal surgeries

    Directory of Open Access Journals (Sweden)

    Wafaa Mohamed Alsadek

    2015-04-01

    Conclusion: TAP block and caudal block under ultrasound guidance proved to be safe with no recorded complications either intra or postoperatively. Patient and parent satisfaction was markedly observed in case of TAP block.

  1. Chain exchange in block copolymer micelles

    Science.gov (United States)

    Lu, Jie; Bates, Frank; Lodge, Timothy

    2014-03-01

    Block copolymer micelles are aggregates formed by self-assembly of amphiphilic copolymers dispersed in a selective solvent, driven by unfavorable interactions between the solvent and the core-forming block. Due to the relatively long chains being subject to additional thermodynamic and dynamic constraints (e.g., entanglements, crystallinity, vitrification), block copolymer micelles exhibit significantly slower equilibration kinetics than small molecule surfactants. As a result, details of the mechanism(s) of equilibration in block copolymer micelles remain unclear. This present works focuses on the chain exchange kinetics of poly(styrene-b-ethylenepropylene) block copolymers in squalane (C30H62) using time-resolved small angle neutron scattering (TR-SANS). A mixture of h-squalane and d-squalane is chosen so that it contrast matches a mixed 50/50 h/d polystyrene micelle core. When the temperature is appropriate and isotopically labeled chains undergo mixing, the mean core contrast with respect to the solvent decreases, and the scattering intensity is therefore reduced. This strategy allows direct probing of chain exchange rate from the time dependent scattering intensity I(q, t).

  2. Numerical modelling of rise and fall of a dense layer in salt diapirs

    DEFF Research Database (Denmark)

    Chemia, Zurab; Koyi, H.; Schmeling, H.

    2008-01-01

    Numerical models are used to study the entrainment of a dense anhydrite layer by a diapir. The anhydrite layer is initially horizontally embedded within a viscous salt layer. The diapir is down-built by aggradation of non-Newtonian sediments (n = 4, constant temperature) placed on the top...... transported into the diapir. Model results show that viscous salt is capable of carrying separate blocks of the anhydrite layer to relatively higher stratigraphic levels. Varying the width of the initial perturbation (in our calculations 400-800 m), from which a diapir triggers, shows that wider diapirs can...... an embedded dense layer. However, the model results show that the entrained blocks inevitably sink back if the rise rate of the diapir is less than the rate of descent of the anhydrite layer or the diapir is permanently covered by a stiff overburden in case of high sedimentation rates....

  3. Partial transmission block production for real efficient method of block and MLC

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ji Min; Park, Ju Young; Ju, Sang Kyu; Park, Jong Ho [Dept. of Radiation Oncology, Samsung Medical Center, Sunkyunkwan University, Seoul (Korea, Republic of)

    2004-09-15

    The Vaginal, the urethra, the vulva and anal cancer avoid the many dose to femur head and the additional treatment is necessary in inguinal LN. The partial transmission block to use inguinal LN addition there is to a method which it treats and produce partial transmission block a method and the MLC which to it analyzes. The Inguinal the LN treatment patient partial transmission it used block and the MLC in the object and with solid water phantom with the patient it reappeared the same depth. In order to analyze the error of the junction the EDR2 (Extended dose range, the Kodak and the U.S) it used the Film and it got film scanner it got the beam profile. The partial transmission block and the MLC bias characteristic, accuracy and stability of production for, it shared at hour and comparison it analyzed. The partial the transmission block compares in the MLC and the block production is difficult and production hour also above 1 hours. The custom the block the place where it revises the error of the junction is a difficult problem. If use of the MLC the fabrication will be break and only the periodical calibration of the MLC it will do and it will be able to use easily. The Inguinal there is to LN treatment and partial transmission block and the MLC there is efficiency of each one but there is a place where the junction of block for partial transmission block the production hour is caught long and it fixes and a point where the control of the block is difficult. Like this problem it transfers with the MLC and if it treats, it means the effective treatment will be possible.

  4. Partial transmission block production for real efficient method of block and MLC

    International Nuclear Information System (INIS)

    The Vaginal, the urethra, the vulva and anal cancer avoid the many dose to femur head and the additional treatment is necessary in inguinal LN. The partial transmission block to use inguinal LN addition there is to a method which it treats and produce partial transmission block a method and the MLC which to it analyzes. The Inguinal the LN treatment patient partial transmission it used block and the MLC in the object and with solid water phantom with the patient it reappeared the same depth. In order to analyze the error of the junction the EDR2 (Extended dose range, the Kodak and the U.S) it used the Film and it got film scanner it got the beam profile. The partial transmission block and the MLC bias characteristic, accuracy and stability of production for, it shared at hour and comparison it analyzed. The partial the transmission block compares in the MLC and the block production is difficult and production hour also above 1 hours. The custom the block the place where it revises the error of the junction is a difficult problem. If use of the MLC the fabrication will be break and only the periodical calibration of the MLC it will do and it will be able to use easily. The Inguinal there is to LN treatment and partial transmission block and the MLC there is efficiency of each one but there is a place where the junction of block for partial transmission block the production hour is caught long and it fixes and a point where the control of the block is difficult. Like this problem it transfers with the MLC and if it treats, it means the effective treatment will be possible.

  5. Improved electron transport layer

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution; a...... method of preparing a zinc oxide electron transporting layer, which method comprises: i) coating a substrate with the coating ink of the present invention to form a film; ii) drying the film; and iii) heating the dry film to convert the zinc acetate substantially to ZnO; a method of preparing an organic...... photovoltaic device or an organic LED having a zinc oxide electron transport layer, the method comprising, in this order: a) providing a substrate bearing a first electrode layer; b) forming an electron transport layer according to the following method: i) coating a coating ink comprising an ink according to...

  6. A novel image block cryptosystem based on a spatiotemporal chaotic system and a chaotic neural network

    Institute of Scientific and Technical Information of China (English)

    Wang Xing-Yuan; Bao Xue-Mei

    2013-01-01

    In this paper,we propose a novel block cryptographic scheme based on a spatiotemporal chaotic system and a chaotic neural network (CNN).The employed CNN comprises a 4-neuron layer called a chaotic neuron layer (CNL),where the spatiotemporal chaotic system participates in generating its weight matrix and other parameters.The spatiotemporal chaotic system used in our scheme is the typical coupled map lattice (CML),which can be easily implemented in parallel by hardware.A 160-bit-long binary sequence is used to generate the initial conditions of the CML.The decryption process is symmetric relative to the encryption process.Theoretical analysis and experimental results prove that the block cryptosystem is secure and practical,and suitable for image encryption.

  7. A new static induction thyristor with high forward blocking voltage and excellent switching performances

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Caizhen; Wang Yongshun; Liu Chunjuan; Wang Zaixing, E-mail: wangysh@mail.lzjtu.c [School of Electronic and Information Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China)

    2010-03-15

    A new static induction thyristor (SITH) with a strip anode region and p{sup -} buffer layer structure (SAP{sup -}B) has been successfully designed and fabricated. This structure is composed of a p{sup -} buffer layer and lightly doped n{sup -} regions embedded in the p{sup +}-emitter. Compared with the conventional structure of a buried-gate with a diffused source region (DSR buried-gate), besides the simple fabrication process, the forward blocking voltage of this SITH has been increased to 1600 V from the previous value of 1000 V, the blocking gain increased from 40 to 70, and the turn-off time decreased from 0.8 to 0.4 {mu}s. (semiconductor integrated circuits)

  8. GaAs Blocked-Impurity-Band Detectors for Far-Infrared Astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, Benjamin Lewin [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    High-purity and doped GaAs films have been grown by Liquid-phase epitaxy (LPE) for development of a blocked impurity band (BIB) detector for far-infrared radiation. The film growth process developed has resulted in the capability to grow GaAs with a net active impurity concentration below 1 x 1013 cm-3, ideal for the blocking layer of the BIB detector. The growth of n-type LPE GaAs films with donor concentrations below the metal-insulator transition, as required for the absorbing layer of a BIB detector, has been achieved. The control of the donor concentration, however, was found to be insufficient for detector production. The growth by LPE of a high-purity film onto a commercially grown vapor-phase epitaxial (VPE) n-type GaAs doped absorbing layer resulted in a BIB device that showed a significant reduction in the low-temperature dark current compared to the absorbing layer only. Extended optical response was not detected, most likely due to the high compensation of the commercially grown GaAs absorbing layer, which restricts the depletion width of the device.

  9. Frequency of block displacements at the north pole of Mars based on HiRISE images

    Science.gov (United States)

    Fanara, Lida; Gwinner, Klaus; Hauber, Ernst; Oberst, Juergen

    2016-10-01

    We identify active block displacements at the foot of the steep north polar scarps of Mars and estimate the frequency of these events. This will help us improve our knowledge of the erosion rate and evolution of the north polar cap. Thousands of single-block movements or events involving multiple blocks have been captured within 10 years of repeated high resolution imaging of the north polar cap's margins by High Resolution Imaging Experiment (HiRISE). These blocks, which are up to a couple of cubic meters in size, become detached either from the North Polar Layered Deposits (NPLD) or the Basal Unit (BU) [1] and come to rest intact or after breaking up into smaller fragments. We detect the new blocks automatically in co-registered images taken at different times. For the co-registration we use Ames Stereo Pipeline [2] to produce HiRISE Digital Terrain Models (DTMs) and ortho-rectify the images on these DTMs. We focus on retrieving the frequency of the events as well as the sizes and shapes of the moved blocks. Our results suggest that rock falls are presently an important, regular recurring seasonal process for certain areas of the north polar scarps. Estimates of the volume of the mass movements and hence the erosion rate are supported by analysis of corresponding DTMs.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement no 607379.References:[1] Russell et al., Landslide erosion rates of north polar layered deposit cliffs and the underlying basal unit, Eighth International Conference on Mars, 2014[2] Moratto et al., Ames Stereo Pipeline, NASA's Open Source Automated Stereogrammetry Software, LPSC, 2010

  10. Liquid phase epitaxial growth and characterization of germanium far infrared blocked impurity band detectors

    International Nuclear Information System (INIS)

    Germanium Blocked Impurity Band (BIB) detectors require a high purity blocking layer ( and lt; 10(sup 13) cm(sup -3)) approximately 1 mm thick grown on a heavily doped active layer ((approx) 10(sup 16) cm(sup -3)) approximately 20 mm thick. Epilayers were grown using liquid phase epitaxy (LPE) of germanium out of lead solution. The effects of the crystallographic orientation of the germanium substrate on LPE growth modes were explored. Growth was studied on substrates oriented by Laue x-ray diffraction between 0.02(sup o) and 10(sup o) from the(lbrace)111(rbrace) toward the(lbrace)100(rbrace). Terrace growth was observed, with increasing terrace height for larger misorientation angles. It was found that the purity of the blocking layer was limited by the presence of phosphorus in the lead solvent. Unintentionally doped Ge layers contained(approx)10(sup 15) cm(sup -3) phosphorus as determined by Hall effect measurements and Photothermal Ionization Spectroscopy (PTIS). Lead purification by vacuum distillation and dilution reduced the phosphorus concentration in the layers to(approx) 10(sup 14) cm(sup -3) but further reduction was not observed with successive distillation runs. The graphite distillation and growth components as an additional phosphorus source cannot be ruled out. Antimony ((approx)10(sup 16) cm(sup -3)) was used as a dopant for the active BIB layer. A reduction in the donor binding energy due to impurity banding was observed by variable temperature Hall effect measurements. A BIB detector fabricated from an Sb-doped Ge layer grown on a pure substrate showed a low energy photoconductive onset ((approx)6 meV). Spreading resistance measurements on doped layers revealed a nonuniform dopant distribution with Sb pile-up at the layer surface, which must be removed by chemomechanical polishing. Sb diffusion into the pure substrate was observed by Secondary Ion Mass Spectroscopy (SIMS) for epilayers grown at 650 C. The Sb concentration at the interface dropped

  11. Liquid phase epitaxial growth and characterization of germanium far infrared blocked impurity band detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bandaru, Jordana

    2001-05-12

    Germanium Blocked Impurity Band (BIB) detectors require a high purity blocking layer (< 10{sup 13} cm{sup -3}) approximately 1 mm thick grown on a heavily doped active layer ({approx} 10{sup 16} cm{sup -3}) approximately 20 mm thick. Epilayers were grown using liquid phase epitaxy (LPE) of germanium out of lead solution. The effects of the crystallographic orientation of the germanium substrate on LPE growth modes were explored. Growth was studied on substrates oriented by Laue x-ray diffraction between 0.02{sup o} and 10{sup o} from the {l_brace}111{r_brace} toward the {l_brace}100{r_brace}. Terrace growth was observed, with increasing terrace height for larger misorientation angles. It was found that the purity of the blocking layer was limited by the presence of phosphorus in the lead solvent. Unintentionally doped Ge layers contained {approx}10{sup 15} cm{sup -3} phosphorus as determined by Hall effect measurements and Photothermal Ionization Spectroscopy (PTIS). Lead purification by vacuum distillation and dilution reduced the phosphorus concentration in the layers to {approx} 10{sup 14} cm{sup -3} but further reduction was not observed with successive distillation runs. The graphite distillation and growth components as an additional phosphorus source cannot be ruled out. Antimony ({approx}10{sup 16} cm{sup -3}) was used as a dopant for the active BIB layer. A reduction in the donor binding energy due to impurity banding was observed by variable temperature Hall effect measurements. A BIB detector fabricated from an Sb-doped Ge layer grown on a pure substrate showed a low energy photoconductive onset ({approx}6 meV). Spreading resistance measurements on doped layers revealed a nonuniform dopant distribution with Sb pile-up at the layer surface, which must be removed by chemomechanical polishing. Sb diffusion into the pure substrate was observed by Secondary Ion Mass Spectroscopy (SIMS) for epilayers grown at 650 C. The Sb concentration at the interface

  12. Boosting water oxidation layer-by-layer.

    Science.gov (United States)

    Hidalgo-Acosta, Jonnathan C; Scanlon, Micheál D; Méndez, Manuel A; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert H

    2016-04-01

    Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and sizes. UV/vis spectroscopic and spectro-electrochemical studies confirmed that the total surface coverage and electrochemically addressable surface coverage of IrO2 NPs increased linearly with the number of bilayers up to 10 bilayers. The voltammetry of the modified electrode was that of hydrous iridium oxide films (HIROFs) with an observed super-Nernstian pH response of the Ir(iii)/Ir(iv) and Ir(iv)-Ir(iv)/Ir(iv)-Ir(v) redox transitions and Nernstian shift of the oxygen evolution onset potential. The overpotential of the oxygen evolution reaction (OER) was essentially pH independent, varying only from 0.22 V to 0.28 V (at a current density of 0.1 mA cm(-2)), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO2/PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13). This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology. PMID:26977761

  13. Concentration Dependent Structure of Block Copolymer Solutions

    Science.gov (United States)

    Choi, Soohyung; Bates, Frank S.; Lodge, Timothy P.

    2015-03-01

    Addition of solvent molecules into block copolymer can induce additional interactions between the solvent and both blocks, and therefore expands the range of accessible self-assembled morphologies. In particular, the distribution of solvent molecules plays a key role in determining the microstructure and its characteristic domain spacing. In this study, concentration dependent structures formed by poly(styrene-b-ethylene-alt-propylene) (PS-PEP) solution in squalane are investigated using small-angle X-ray scattering. This reveals that squalane is essentially completely segregated into the PEP domains. In addition, the conformation of the PS block changes from stretched to nearly fully relaxed (i.e., Gaussian conformation) as amounts of squalane increases. NRF

  14. Understanding dwarf galaxies as galactic building blocks

    CERN Document Server

    Tosi, M P

    2003-01-01

    This is a summary of a general discussion held during the third EuroConference on galaxy evolution. Various observational features of the stellar populations in present--day dwarf galaxies were presented to introduce the discussion on the possibility that these systems be the main building blocks of spiral and elliptical galaxies. Many people in the audience turned out to think that the inconsistencies among the observed properties of large and dwarf galaxies are too many to believe that the former are built up only by means of successive accretions of the latter. However, theorists of hierarchical galaxy formation suggested that present--day dwarfs are not representative of the galactic building blocks, which may be completely invisible nowadays. Some of them suggested that, contrary to what is usually assumed in hierarchical modelling, the actual building blocks were still fully gaseous systems when their major mergers occurred. If this is the case, then most of the inconsistencies can be overcome, and the ...

  15. Non-blocking message total ordering protocol

    Institute of Scientific and Technical Information of China (English)

    WANG Yun; WANG JunLing

    2008-01-01

    Message total ordering is a critical part in active replication in order to maintain consistency among members in a fault tolerant group. The paper proposes a non-blocking message total ordering protocol (NBTOP) for distributed systems. Non-blocking property refers to that the members in a fault tolerant group keep on running independently without waiting for installing the same group view when a fault tolerant group evolves even when decision messages collide. NBTOP takes advantage of token ring as its logical control way. Members adopt re-requesting mechanism (RR) to obtain their lost decisions. Forward acknowledgement mechanism (FA) is put forth to solve decision collisions. The paper further proves that NBTOP satisfies the properties of total order, agreement, and termination. NBTOP is implemented, and its performance test is done. Comparing with the performance of Totem, the results show that NBTOP has a better total ordering delay. It manifests that non-blocking property helps to improve protocol efficiency.

  16. Radial expansion for spinning conformal blocks

    CERN Document Server

    Costa, Miguel$uPorto U.; Hansen, Tobias; Penedones, João; Trevisani, Emilio

    2016-01-01

    This paper develops a method to compute any bosonic conformal block as a series expansion in the optimal radial coordinate introduced by Hogervorst and Rychkov. The method reduces to the known result when the external operators are all the same scalar operator, but it allows to compute conformal blocks for external operators with spin. Moreover, we explain how to write closed form recursion relations for the coefficients of the expansions. We study three examples of four point functions in detail: one vector and three scalars; two vectors and two scalars; two spin 2 tensors and two scalars. Finally, for the case of two external vectors, we also provide a more efficient way to generate the series expansion using the analytic structure of the blocks as a function of the scaling dimension of the exchanged operator.

  17. Radial expansion for spinning conformal blocks

    Science.gov (United States)

    Costa, Miguel S.; Hansen, Tobias; Penedones, João; Trevisani, Emilio

    2016-07-01

    This paper develops a method to compute any bosonic conformal block as a series expansion in the optimal radial coordinate introduced by Hogervorst and Rychkov. The method reduces to the known result when the external operators are all the same scalar operator, but it allows to compute conformal blocks for external operators with spin. Moreover, we explain how to write closed form recursion relations for the coefficients of the expansions. We study three examples of four point functions in detail: one vector and three scalars; two vectors and two scalars; two spin 2 tensors and two scalars. Finally, for the case of two external vectors, we also provide a more efficient way to generate the series expansion using the analytic structure of the blocks as a function of the scaling dimension of the exchanged operator.

  18. Parametric dependence of irregular conformal block

    CERN Document Server

    Choi, Sang-Kwan

    2013-01-01

    Irregular conformal block is an important tool to study a new type of conformal theories, which can be constructed as the colliding limit of the regular conformal block. The irregular conformal block is realized as the $\\beta$-deformed Penner matrix model whose partition function is regarded as the inner product of the irregular modules. The parameter dependence of the inner product is obtained explicitly using the loop equation with close attention to singularities in the parameter space. It is noted that the exact singular structure of the parameter space in general can be found using a very simple and powerful method which uses the flow equations of the partition function together with the hierarchical structure of the singularity. This method gives the exact expression to all orders of large $N$ expansion without using the explicit contour integral of the filling fraction.

  19. Micellization and Characterization of Block Copolymer Detergents

    DEFF Research Database (Denmark)

    Hvidt, Søren

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are used widely in industry as emulsifiers, anti-foaming agents, and in delayed drug release. EPE copolymers form micelles with a core of P blocks and different micellar shapes...... depending on block length ratios and temperature. The micellization process with increasing temperature or concentration has been followed by a number of techniques including differential scanning calorimetry and surface tension measurements. The detailed micellar mechanism is not well understood and...... different models have been proposed. Results obtained by a range of liquid chromatographic methods will be shown and it will be demonstrated that commercial EPE copolymers are inhomogeneous at several levels and many of their unusual properties reflect the presence of impurities....

  20. Effects of 4X4 Block Scheduling

    Directory of Open Access Journals (Sweden)

    R. Brian Cobb

    1999-02-01

    Full Text Available The effects of a 4 X 4 block scheduling program in a middle school on a variety of student measures were investigated. These measures included standardized achievement tests in mathematics, reading, and writing, cumulative and semester grades in middle school and high school, attendance rates, and enrollment rates in advanced high school courses (in mathematics only. The block scheduling program had been in effect for four years allowing analyses of current middle and high school students who had experienced a minimum of one and one-half years of block scheduling while in middle school. The primary research design was a post-test only, matched pairs design. Students were matched on school characteristics, gender, ethnicity, grade level, and 5th grade standardized reading scores. Results were relatively consistent with the extant literature and generally positive.

  1. Biodegradable amphiphilic block copolymers containing functionalized PEO blocks:Controlled synthesis and biomedical potentials

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO) as the hydrophilic block and poly(ε-caprolactone)(PCL) as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2) were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH) and functional compounds RGD(PCL-b-PEO-RGD) as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM) were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC) and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD) into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.

  2. Ipsilateral Brachial Plexus Block and Hemidiaphragmatic Paresis as Adverse Effect of a High Thoracic Paravertebral Block

    NARCIS (Netherlands)

    Renes, Steven H.; van Geffen, Geert J.; Snoeren, Miranda M.; Gielen, Matthieu J.; Groen, Gerbrand J.

    2011-01-01

    Background: Thoracic paravertebral block is regularly used for unilateral chest and abdominal surgery and is associated with a low complication rate. Case Reports: We describe 2 patients with an ipsilateral brachial plexus block with Horner syndrome after a high continuous thoracic paravertebral blo

  3. Production blocking and idea generation : Does blocking interfere with cognitive processes?

    NARCIS (Netherlands)

    Nijstad, BA; Stroebe, W; Lodewijkx, HFM

    2003-01-01

    Production blocking (group members must take turns expressing their ideas) is an important cause of productivity loss in brainstorming groups. However, it is not yet clear why production blocking has this detrimental effect. We hypothesized that delays between the generation and articulation of idea

  4. Chinese Basic Block - The Structure Designing Principle and Technology of Dong Hua Basic Block

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-bin; ZHANG Wei-yuan

    2002-01-01

    The principles and the interrelated factors of the basic garment pattern are discussed. Furthermore the regression relation between the different parts of the Chinese female bodies and the application rules of the box pattern are analyzed. Chinese basic block - the DongHua Basic Block is founded theoretically and practically.

  5. Block Play: It's Not Just for Boys Anymore--Strategies for Encouraging Girls' Block Play

    Science.gov (United States)

    Tokarz, Barb

    2008-01-01

    While block play is essential for both boys' and girls' social, cognitive, language, and motor development, girls do not engage in block play as frequently as boys. This situation can be attributed to the socialization process--children learn societal expectations for behavior and materials for both boys and girls--lack of experience for girls…

  6. Block by Block: Neighborhoods and Public Policy on Chicago's West Side. Historical Studies of Urban America

    Science.gov (United States)

    Seligman, Amanda I.

    2005-01-01

    In the decades following World War II, cities across the United States saw an influx of African American families into otherwise homogeneously white areas. This racial transformation of urban neighborhoods led many whites to migrate to the suburbs, producing the phenomenon commonly known as white flight. In "Block by Block," Amanda I. Seligman…

  7. S-layer architectures : extending the morphogenetic potential of S-layer protein self-assembly

    International Nuclear Information System (INIS)

    Self-assembly of molecular building blocks is a common principle for bottom up based building principles in nature. One example are crystalline bacterial surface layers, termed S-layers, which are the most commonly observed cell surface structures in prokaryotic organisms. They recrystallize into highly ordered, porous protein meshworks with unit cell sizes of 3 to 30 nm and pore sizes of 2 to 8 nm. In this work, S-layers were self-assembled on various three dimensional scaffolds in order to fabricate novel S-layer architectures. Exploiting the stabilizing effect of silica deposited on the S-layer protein meshwork led to the construction of hollow S-layer nano-containers derived from coated liposomes. Transmission electron microscopy (TEM) techniques and release experiments with fluorescent dyes confirmed the dissolution of the supporting lipids. Silica deposition on different spherical particles in solution, as well as on planar S-layer coated surfaces, could be monitored by measuring the ζ-potential, the decline of monosilicic acid in solution, by using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis or by quartz crystal microbalance with dissipation monitoring (QCM-D). Both, ζ-potential and release experiments showed differences between silicified plain liposomes and silicified S-layer coated liposomes. In addition, nanocapsules with calcium carbonate cores served as another template for the construction of silica supported S-layer architectures. These were investigated by SEM and fluorescence microscopy after fluorescence labeling. Additional coating with polyelectrolytes increased the stability of the nanocapsules. Their mechanical properties were characterized by atomic force microscopy (AFM). The influence of silica deposition was investigated by AFM and SEM. Further on, emulsomes and gas filled lipid supported microbubbles may serve as other templates for the design of spherical protein constructs although extraction of the

  8. Ultraviolet light-emitting diodes with polarization-doped p-type layer

    Science.gov (United States)

    Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Liangliang; Xia, Chao; Yuan, Songyang; Yin, Yian; Li, Shuti

    2016-09-01

    We report ultraviolet light emitting diode (LEDs) with polarization doped p-type layer. Fabricated LEDs with polarization doped p-type layer exhibited reduced forward voltage and enhanced light output power, compared to those with traditional p-type AlGaN layer. The improvement is attributed to improved hole concentration and the smooth valence band by the polarization enhanced p-type doping. Our simulated results reveal that this p-type layer can further enhance the performance of ultraviolet LEDs by removing the electron blocking layer (EBL).

  9. STUDY ON STRATEGY OF DYNAMIC JOINT ROUTING AND RESOURCE ALLOCATION IN LAYERED OPTICAL TRANSPORT NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Su Yang; Xu Zhanqi; Zhao Ruiqin; Liu Zengji

    2008-01-01

    A layered network model for optical transport networks is proposed in this paper, which involves Internet Protocol (IP), Synchronous Digital Hierarchy (SDH) and Wavelength Division Multiplexing (WDM) layers. The strategy of Dynamic Joint Routing and Resource Allocation (DJRRA) and its algorithm description are also presented for the proposed layered network model. DJRRA optimizes the bandwidth usage of interface links between different layers and the logic links inside all layers. The simulation results show that DJRRA can reduce the blocking probability and increase network throughput effectively, which is in contrast to the classical separate sequential routing and resource allocation solutions.

  10. Wilson loop invariants from WN conformal blocks

    Science.gov (United States)

    Alekseev, Oleg; Novaes, Fábio

    2015-12-01

    Knot and link polynomials are topological invariants calculated from the expectation value of loop operators in topological field theories. In 3D Chern-Simons theory, these invariants can be found from crossing and braiding matrices of four-point conformal blocks of the boundary 2D CFT. We calculate crossing and braiding matrices for WN conformal blocks with one component in the fundamental representation and another component in a rectangular representation of SU (N), which can be used to obtain HOMFLY knot and link invariants for these cases. We also discuss how our approach can be generalized to invariants in higher-representations of WN algebra.

  11. Wilson loop invariants from WN conformal blocks

    Directory of Open Access Journals (Sweden)

    Oleg Alekseev

    2015-12-01

    Full Text Available Knot and link polynomials are topological invariants calculated from the expectation value of loop operators in topological field theories. In 3D Chern–Simons theory, these invariants can be found from crossing and braiding matrices of four-point conformal blocks of the boundary 2D CFT. We calculate crossing and braiding matrices for WN conformal blocks with one component in the fundamental representation and another component in a rectangular representation of SU(N, which can be used to obtain HOMFLY knot and link invariants for these cases. We also discuss how our approach can be generalized to invariants in higher-representations of WN algebra.

  12. WZW superconformal blocks from three dimensions

    International Nuclear Information System (INIS)

    A three-dimensional theory whose canonical quantization yields wavefunctions which can be identified with the superconformal blocks of two-dimensional super-Wess-Zumino-Witten theory is presented. In particular, the anomalous Ward identities satisfied by the superconformal blocks in the presence of a supergauge background are reproduced in terms of constraints obeyed by the wavefunctions of the three-dimensional theory. The action contains the bosonic Chern-Simons action but does not possess a three-dimensional supersymmetry. The 'time' coordinate plays the role of an interpolating parameter between two-dimensional superconnections. The structure of the Hilbert space of the theory is examined. (orig.)

  13. Ophthalmic regional blocks: management, challenges, and solutions

    Directory of Open Access Journals (Sweden)

    Palte HD

    2015-08-01

    Full Text Available Howard D Palte Department of Anesthesiology, Perioperative Medicine and Pain Management, Miller School of Medicine, University of Miami, Miami, FL, USA Abstract: In the past decade ophthalmic anesthesia has witnessed a major transformation. The sun has set on the landscape of ophthalmic procedures performed under general anesthesia at in-hospital settings. In its place a new dawn has ushered in the panorama of eye surgeries conducted under regional and topical anesthesia at specialty eye care centers. The impact of the burgeoning geriatric population is that an increasing number of elderly patients will present for eye surgery. In order to accommodate increased patient volumes and simultaneously satisfy administrative initiatives directed at economic frugality, administrators will seek assistance from anesthesia providers in adopting measures that enhance operating room efficiency. The performance of eye blocks in a holding suite meets many of these objectives. Unfortunately, most practicing anesthesiologists resist performing ophthalmic regional blocks because they lack formal training. In future, anesthesiologists will need to block eyes and manage common medical conditions because economic pressures will eliminate routine preoperative testing. This review addresses a variety of topical issues in ophthalmic anesthesia with special emphasis on cannula and needle-based blocks and the new-generation antithrombotic agents. In a constantly evolving arena, the sub-Tenon’s block has gained popularity while the deep angulated intraconal (retrobulbar block has been largely superseded by the shallower extraconal (peribulbar approach. Improvements in surgical technique have also impacted anesthetic practice. For example, phacoemulsification techniques facilitate the conduct of cataract surgery under topical anesthesia, and suture-free vitrectomy ports may cause venous air embolism during air/fluid exchange. Hyaluronidase is a useful adjuvant because it

  14. Block floating point for radar data

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz

    1999-01-01

    Integer, floating point, and block floating point (BFP) data formats are analyzed and compared in order to establish the mathematical tools for selection of an optimal format which fulfils the demands of high resolution radar (SAR) data to large dynamic range and adequate S/N. The analysis takes...... quantization noise and saturation distortion into account and concludes that it is preferred to use small blocks and a (new) modified BFP format applying fractional exponents. Data from the EMISAR radar system are applied to illustrate the merits of the different schemes....

  15. Building blocks for subleading helicity operators

    Science.gov (United States)

    Kolodrubetz, Daniel W.; Moult, Ian; Stewart, Iain W.

    2016-05-01

    On-shell helicity methods provide powerful tools for determining scattering amplitudes, which have a one-to-one correspondence with leading power helicity operators in the Soft-Collinear Effective Theory (SCET) away from singular regions of phase space. We show that helicity based operators are also useful for enumerating power suppressed SCET operators, which encode subleading amplitude information about singular limits. In particular, we present a complete set of scalar helicity building blocks that are valid for constructing operators at any order in the SCET power expansion. We also describe an interesting angular momentum selection rule that restricts how these building blocks can be assembled.

  16. Superconvergence of tricubic block finite elements

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we first introduce interpolation operator of projection type in three dimen- sions, from which we derive weak estimates for tricubic block finite elements. Then using the estimate for the W 2, 1-seminorm of the discrete derivative Green’s function and the weak estimates, we show that the tricubic block finite element solution uh and the tricubic interpolant of projection type Πh3u have superclose gradient in the pointwise sense of the L∞-norm. Finally, this supercloseness is applied to superconvergence analysis, and the global superconvergence of the finite element approximation is derived.

  17. Quantization of the space of conformal blocks

    CERN Document Server

    Mukhin, E

    1997-01-01

    We consider the discrete Knizhnik-Zamolodchikov connection (qKZ) associated to $gl(N)$, defined in terms of rational R-matrices. We prove that under certain resonance conditions, the qKZ connection has a non-trivial invariant subbundle which we call the subbundle of quantized conformal blocks. The subbundle is given explicitly by algebraic equations in terms of the Yangian $Y(gl(N))$ action. The subbundle is a deformation of the subbundle of conformal blocks in CFT. The proof is based on an identity in the algebra with two generators $x,y$ and defining relation $xy=yx+yy$.

  18. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars;

    2016-01-01

    Block copolymer (BC) self-assembly constitutes a powerful platform for nanolithography. However, there is a need for a general approach to BC lithography that critically considers all the steps from substrate preparation to the final pattern transfer. We present a procedure that significantly sim...... plasma treatment enables formation of the oxidized PDMS hard mask, PS block removal and polymer or graphene substrate patterning....... simplifies the main stream BC lithography process, showing a broad substrate tolerance and allowing for efficient pattern transfer over wafer scale. PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are directly applied on substrates including polymers, silicon and graphene. A single oxygen...

  19. The Equatorial Ekman Layer

    CERN Document Server

    Marcotte, Florence; Soward, Andrew

    2016-01-01

    The steady incompressible viscous flow in the wide gap between spheres rotating about a common axis at slightly different rates (small Ekman number E) has a long and celebrated history. The problem is relevant to the dynamics of geophysical and planetary core flows, for which, in the case of electrically conducting fluids, the possible operation of a dynamo is of considerable interest. A comprehensive asymptotic study, in the limit E<<1, was undertaken by Stewartson (J. Fluid Mech. 1966, vol. 26, pp. 131-144). The mainstream flow, exterior to the E^{1/2} Ekman layers on the inner/outer boundaries and the shear layer on the inner sphere tangent cylinder C, is geostrophic. Stewartson identified a complicated nested layer structure on C, which comprises relatively thick quasi-geostrophic E^{2/7} (inside C) and E^{1/4} (outside C) layers. They embed a thinner E^{1/3} ageostrophic shear layer (on C), which merges with the inner sphere Ekman layer to form the E^{2/5} Equatorial Ekman layer of axial length E^{...

  20. Multi-layer coatings

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoodi, Sina; Brophy, Brenor L.; Abrams, Ze' ev R.; Gonsalves, Peter R.

    2016-06-28

    Disclosed herein are coating materials and methods for applying a top-layer coating that is durable, abrasion resistant, highly transparent, hydrophobic, low-friction, moisture-sealing, anti-soiling, and self-cleaning to an existing conventional high temperature anti-reflective coating. The top coat imparts superior durability performance and new properties to the under-laying conventional high temperature anti-reflective coating without reducing the anti-reflectiveness of the coating. Methods and data for optimizing the relative thickness of the under-layer high temperature anti-reflective coating and the top-layer thickness for optimizing optical performance are also disclosed.

  1. The Application of Layer Theory to Design: The Control Layer

    Science.gov (United States)

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  2. Layers of Discourse in Preschool Block Play: An Examination of Children's Social Interactions

    Science.gov (United States)

    Cohen, Lynn E.

    2015-01-01

    Mikhail Bakhtin's philosophical orientation concerning dialogism offers a challenge to contemporary play theory. This study demonstrates the benefits of a Bakhtinian analysis of double voicing in early childhood programs. Bakhtin's notion of dialogism, specifically Bakhtin's ideas on genre and utterance, has received less attention in the analysis…

  3. Heparin-containing block copolymers, Part I: Surface characterization

    NARCIS (Netherlands)

    Vulić, I.; Pijpers, A.P.; Okano, T.; Kim, S.W.; Feijen, J.

    1993-01-01

    Newly synthesized heparin-containing block copolymers, consisting of a hydrophobic block of polystyrene (PS), a hydrophilic spacer-block of poly(ethylene oxide) (PEO) and covalently bound heparin (Hep) as bioactive block, were coated on aluminium, glass, polydimethylsiloxane (PDMS), PS or Biomer sub

  4. 30 CFR 250.611 - Traveling-block safety device.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Traveling-block safety device. 250.611 Section... Traveling-block safety device. After May 31, 1989, all units being used for well-workover operations which have both a traveling block and a crown block shall be equipped with a safety device which is...

  5. 30 CFR 250.511 - Traveling-block safety device.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Traveling-block safety device. 250.511 Section... Traveling-block safety device. All units being used for well-completion operations that have both a traveling block and a crown block must be equipped with a safety device that is designed to prevent...

  6. Block Scheduling: Center for School Success Promising Practices Series

    Science.gov (United States)

    Imbimbo, Josephine; Gilkes, Alwyn

    2009-01-01

    This publication focuses on block scheduling. Alternative scheduling models--usually called "block scheduling" because they involve blocks of time for student learning--restructure the school day. Schools may adopt block scheduling to create more productive and personal relationships among teachers and students, to design challenging curricula…

  7. Conditional independence of blocked ordered data

    OpenAIRE

    Iliopoulos, G.; Balakrishnan, N.

    2009-01-01

    Abstract In this paper, we prove that blocks of ordered data formed by some conditioning events are mutually independent. We establish this result by considering the usual order statistics, progressively censored order statistics, and concomitants of order statistics. correspondance: Corresponding author. Tel.: +30 210 4142406. (Iliopoulos, G.) (Iliopoulos, G.) (Balakrishnan, N.) Department of Statis...

  8. Ecology of Great Salt Pond, Block Island

    Science.gov (United States)

    Great Salt Pond is an island of estuarine water on Block Island, which sits in the middle of the Northwest Atlantic Continental Shelf. When the last continental glaciers retreated, they left a high spot on a terminal moraine. The rising sea from melting glaciers formed two island...

  9. Nerve injury caused by mandibular block analgesia

    DEFF Research Database (Denmark)

    Hillerup, S; Jensen, Rigmor H

    2006-01-01

    : feather light touch, pinprick, sharp/dull discrimination, warm, cold, point location, brush stroke direction, 2-point discrimination and pain perception. Gustation was tested for recognition of sweet, salt, sour and bitter. Mandibular block analgesia causes lingual nerve injury more frequently than...

  10. Observations on the SIMON Block Cipher Family

    DEFF Research Database (Denmark)

    Kölbl, Stefan; Leander, Gregor; Tiessen, Tyge

    2015-01-01

    In this paper we analyse the general class of functions underlying the Simon block cipher. In particular, we derive efficiently computable and easily implementable expressions for the exact differential and linear behaviour of Simon-like round functions. Following up on this, we use those express...

  11. Defying Gravity Using Jenga[TM] Blocks

    Science.gov (United States)

    Tan, Yin-Soo; Yap, Kueh-Chin

    2007-01-01

    This paper describes how Jenga[TM] blocks can be used to demonstrate the physics of an overhanging tower that appears to defy gravity. We also propose ideas for how this demonstration can be adapted for the A-level physics curriculum. (Contains 8 figures and 1 table.)

  12. Iron Blocks of CMS Magnet Barrel Yoke.

    CERN Multimedia

    2000-01-01

    On the occasion of presenting the CMS Award 2000 to Deggendorfer Werft und Eisenbau GmbH the delivered blocks were inspected at CERN Point 5. From left to right: H. Gerwig (CERN, CMS Magnet Barrel Yoke Coordinator), G. Waurick (CERN), F. Leher (DWE, Project Engineer) and W. Schuster (DWE, Project Manager).

  13. Seed Conformal Blocks in 4D CFT

    CERN Document Server

    Echeverri, Alejandro Castedo; Karateev, Denis; Serone, Marco

    2016-01-01

    We compute in closed analytical form the minimal set of "seed" conformal blocks associated to the exchange of generic mixed symmetry spinor/tensor operators in an arbitrary representation (l,\\bar l) of the Lorentz group in four dimensional conformal field theories. These blocks arise from 4-point functions involving two scalars, one (0,|l-\\bar l|) and one (|l-\\bar l|,0) spinors or tensors. We directly solve the set of Casimir equations, that can elegantly be written in a compact form for any (l,\\bar l), by using an educated ansatz and reducing the problem to an algebraic linear system. Various details on the form of the ansatz have been deduced by using the so called shadow formalism. The complexity of the conformal blocks depends on the value of p=|l-\\bar l | and grows with p, in analogy to what happens to scalar conformal blocks in d even space-time dimensions as d increases. These results open the way to bootstrap 4-point functions involving arbitrary spinor/tensor operators in four dimensional conformal f...

  14. Building Blocks for Control System Software

    NARCIS (Netherlands)

    Broenink, J.F.; Hilderink, G.H.; Amerongen van, J.; Jonker, B.; Regtien, P.P.L.

    2001-01-01

    Software implementation of control laws for industrial systems seem straightforward, but is not. The computer code stemming from the control laws is mostly not more than 10 to 30% of the total. A building-block approach for embedded control system development is advocated to enable a fast and effici

  15. BLOCK BASED NEWTON-LIKE BLENDING INTERPOLATION

    Institute of Scientific and Technical Information of China (English)

    Qian-jin Zhao; Jie-qing Tan

    2006-01-01

    Newton's polynomial interpolation may be the favourite linear interpolation in the sense that it is built up by means of the divided differences which can be calculated recursively and produce useful intermediate results. However Newton interpolation is in fact point based interpolation since a new interpolating polynomial with one more degree is obtained by adding a new support point into the current set of support points once at a time. In this paper we extend the point based interpolation to the block based interpolation. Inspired by the idea of the modern architectural design, we first divide the original set of support points into some subsets (blocks), then construct each block by using whatever interpolation means, linear or rational and finally assemble these blocks by Newton's method to shape the whole interpolation scheme. Clearly our method offers many flexible interpolation schemes for choices which include the classical Newton's polynomial interpolation as its special case. A bivariate analogy is also discussed and numerical examples are given to show the effectiveness of our method.

  16. Comparing MTI randomization procedures to blocked randomization.

    Science.gov (United States)

    Berger, Vance W; Bejleri, Klejda; Agnor, Rebecca

    2016-02-28

    Randomization is one of the cornerstones of the randomized clinical trial, and there is no shortage of methods one can use to randomize patients to treatment groups. When deciding which one to use, researchers must bear in mind that not all randomization procedures are equally adept at achieving the objective of randomization, namely, balanced treatment groups. One threat is chronological bias, and permuted blocks randomization does such a good job at controlling chronological bias that it has become the standard randomization procedure in clinical trials. But permuted blocks randomization is especially vulnerable to selection bias, so as a result, the maximum tolerated imbalance (MTI) procedures were proposed as better alternatives. In comparing the procedures, we have somewhat of a false controversy, in that actual practice goes uniformly one way (permuted blocks), whereas scientific arguments go uniformly the other way (MTI procedures). There is no argument in the literature to suggest that the permuted block design is better than or even as good as the MTI procedures, but this dearth is matched by an equivalent one regarding actual trials using the MTI procedures. So the 'controversy', if we are to call it that, pits misguided precedent against sound advice that tends to be ignored in practice. We shall review the issues to determine scientifically which of the procedures is better and, therefore, should be used. PMID:26337607

  17. Role of dexamethasone in brachial plexus block

    International Nuclear Information System (INIS)

    To evaluate the effect of dexamethasone added to (lignocaine) on the onset and duration of axillary brachial plexus block. Study Design: Randomized controlled trial. Place and Duration of Study: Combined Military Hospital Rawalpindi, from September 2009 to March 2010. Patients and Methods: A total of 100 patients, who were scheduled for elective hand and forearm surgery under axillary brachial plexus block, were randomly allocated to group A in which patients received 40 ml 1.5% lidocaine with 2 ml of isotonic saline (0.9%) and group B in which patients received 40 ml 1.5% lidocaine with 2 ml of dexamethasone (8 mg). Nerve stimulator with insulated needle for multiple stimulations technique was used to locate the brachial plexus nerves. After the injection onset of action and duration of sensory blockade of brachial plexus were recorded at 5 minutes and 15 minutes interval. Results: Group A showed the onset of action of 21.64 ± 2.30 min and in group B it was 15.42 ± 1.44 min (p< 0.001). Duration of nerve block was 115.08 ± 10.92 min in group A and 265.42 ± 16.56 min in group B (p < 0.001). Conclusion: The addition of dexamethasone to 1.5% lignocaine solution in axillary brachial plexus block prolongs the duration of sensory blockade significantly. (author)

  18. Exploring Energy Efficiency of Lightweight Block Ciphers

    DEFF Research Database (Denmark)

    Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco

    2016-01-01

    lightweight block ciphers, and thereby try to predict the optimal value of r at which an r-round unrolled architecture for a cipher is likely to be most energy efficient. We also try to relate our results to some physical design parameters like the signal delay across a round and algorithmic parameters like...

  19. Block additive functions on the Gaussian integers

    OpenAIRE

    Drmota, Michael; Peter, Grabner,; Liardet, Pierre

    2008-01-01

    International audience We present three conceptually different methods to prove distribution results for block additive functions with respect to radix expansions of the Gaussian integers. Based on generating function approaches we obtain a central limit theorem and asymptotic expansions for the moments. Furthermore, these generating functions as well as ergodic skew products are used to prove uniform distribution in residue classes and modulo 1.

  20. Blocked atrial bigeminy presenting with bradycardia.

    Science.gov (United States)

    Akdeniz, Celal; Tanidir, Ibrahim Cansaran; Tuzcu, Volkan

    2012-01-01

    Blocked premature atrial contractions can cause bradycardia by resetting sinoatrial node and prolonging the RR intervals. Herein, we report the management of a patient with frequent premature atrial contractions in bigeminal pattern. The patient presented with symptomatic bradycardia and was successfully treated with propafenone. PMID:22469245

  1. Building Blocks for Young Children's Mathematical Development.

    Science.gov (United States)

    Sarama, Julie; Clements, Douglas H.

    2002-01-01

    Describes the design principles behind a set of research-based software microworlds included in the "Building Blocks" program, a pre-kindergarten to grade 2 software-based mathematics curriculum. Discusses how to help children extend and mathematize their everyday activities and presents the nine-step design process model used. (Author/LRW)

  2. Layers of the Skin

    Science.gov (United States)

    ... Review Abstracting, Coding, & Staging ICD-O Site Codes Morphology & Grade Extent of Disease Evaluation Physical Exam Lab ... the majority of the structure of the skin, hair, and nails. The squamous cell layer is the ...

  3. Blocking Losses With a Photon Counter

    Science.gov (United States)

    Moision, Burce E.; Piazzolla, Sabino

    2012-01-01

    It was not known how to assess accurately losses in a communications link due to photodetector blocking, a phenomenon wherein a detector is rendered inactive for a short time after the detection of a photon. When used to detect a communications signal, blocking leads to losses relative to an ideal detector, which may be measured as a reduction in the communications rate for a given received signal power, or an increase in the signal power required to support the same communications rate. This work involved characterizing blocking losses for single detectors and arrays of detectors. Blocking may be mitigated by spreading the signal intensity over an array of detectors, reducing the count rate on any one detector. A simple approximation was made to the blocking loss as a function of the probability that a detector is unblocked at a given time, essentially treating the blocking probability as a scaling of the detection efficiency. An exact statistical characterization was derived for a single detector, and an approximation for multiple detectors. This allowed derivation of several accurate approximations to the loss. Methods were also derived to account for a rise time in recovery, and non-uniform illumination due to diffraction and atmospheric distortion of the phase front. It was assumed that the communications signal is intensity modulated and received by an array of photon-counting photodetectors. For the purpose of this analysis, it was assumed that the detectors are ideal, in that they produce a signal that allows one to reproduce the arrival times of electrons, produced either as photoelectrons or from dark noise, exactly. For single detectors, the performance of the maximum-likelihood (ML) receiver in blocking is illustrated, as well as a maximum-count (MC) receiver, that, when receiving a pulse-position-modulated (PPM) signal, selects the symbol corresponding to the slot with the largest electron count. Whereas the MC receiver saturates at high count rates

  4. Layered circle packings

    Directory of Open Access Journals (Sweden)

    David Dennis

    2005-01-01

    Full Text Available Given a bounded sequence of integers {d0,d1,d2,…}, 6≤dn≤M, there is an associated abstract triangulation created by building up layers of vertices so that vertices on the nth layer have degree dn. This triangulation can be realized via a circle packing which fills either the Euclidean or the hyperbolic plane. We give necessary and sufficient conditions to determine the type of the packing given the defining sequence {dn}.

  5. Structured luminescence conversion layer

    Science.gov (United States)

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  6. Iteration Complexity Analysis of Block Coordinate Descent Methods

    OpenAIRE

    Hong, Mingyi; Wang, Xiangfeng; Razaviyayn, Meisam; Luo, Zhi-Quan

    2013-01-01

    In this paper, we provide a unified iteration complexity analysis for a family of general block coordinate descent (BCD) methods, covering popular methods such as the block coordinate gradient descent (BCGD) and the block coordinate proximal gradient (BCPG), under various different coordinate update rules. We unify these algorithms under the so-called Block Successive Upper-bound Minimization (BSUM) framework, and show that for a broad class of multi-block nonsmooth convex problems, all algor...

  7. The Local Balances of Vorticity and Heat for Blocking Anticyclones in a Spectral General Circulation Model.

    Science.gov (United States)

    Mullen, Steven L.

    1986-07-01

    Blocking anticyclones that appear in perpetual January simulations of a spectral general circulation model are examined. Blocks in three geographical regions are studied: the North Pacific, the North Atlantic and western North America. Local time-averaged balances of vorticity and heat are evaluated for composite cases of blocking. The following common relationships emerged from these budgets.The time-mean divergence term is, in general, a flat-order term in the vorticity balance throughout the troposphere and its pattern over severe orography is closely related to the underlying topography. Above the surface layer, the horizontal advection of time-mean absolute vorticity by the mean wind mainly balances the divergence term with the net effect of the time-mean vorticity forcing being a tendency for the blocking pattern to propagate downstream. The transient eddy vorticity transports act to shift the block upstream and hence they mainly offset the downstream tendency due to the time-mean flow; the magnitude of the eddy vorticity term is typically one-third to one-half that of the divergence or advection terms alone. Frictional dissipation is negligible everywhere except near the ground where it primarily offsets the divergence term.The horizontal advection of the time-mean temperature field by the mean wind throughout the troposphere is a first-order term in the beat balance and is mainly responsible for maintaining the block's thermal perturbations; it is predominately balanced by adiabatic heating in the free troposphere and by diabatic heating near the surface. Transient eddy heat transports act to dissipate the block's thermal perturbations at all levels, while diabatic heating does not exhibit a systematic relationship with the temperature field at any level.A quasi-geostrophic diagnosis of the ageostrophic motion field suggests that dynamical processes which strongly affect the vorticity balance may be more important to the maintenance of model blocks than

  8. Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm

    International Nuclear Information System (INIS)

    Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging from 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively

  9. Structural templating of multiple polycrystalline layers in organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lassiter, Brian E; Lunt, Richard R; Renshaw, Kyle; Forrest, Stephen R.

    2010-09-01

    We demonstrate that organic photovoltaic cell performance is influenced by changes in the crystalline orientation of composite layer structures. A 1.5 nm thick self-organized, polycrystalline template layer of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) orients subsequently deposited layers of a diindenoperylene exciton blocking layer, and the donor, copper phthalocyanine (CuPc). Control over the crystalline orientation of the CuPc leads to changes in its frontier energy levels, absorption coefficient, and surface morphology, resulting in an increase of power conversion efficiency at 1 sun from 1.42 ± 0.04% to 2.19 ± 0.05% for a planar heterojunction and from 1.89 ± 0.05% to 2.49 ± 0.03% for a planar-mixed heterojunction.

  10. Structural templating of multiple polycrystalline layers in organic photovoltaic cells.

    Science.gov (United States)

    Lassiter, Brian E; Lunt, Richard R; Renshaw, C Kyle; Forrest, Stephen R

    2010-09-13

    We demonstrate that organic photovoltaic cell performance is influenced by changes in the crystalline orientation of composite layer structures. A 1.5 nm thick self-organized, polycrystalline template layer of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) orients subsequently deposited layers of a diindenoperylene exciton blocking layer, and the donor, copper phthalocyanine (CuPc). Control over the crystalline orientation of the CuPc leads to changes in its frontier energy levels, absorption coefficient, and surface morphology, resulting in an increase of power conversion efficiency at 1 sun from 1.42 ± 0.04% to 2.19 ± 0.05% for a planar heterojunction and from 1.89 ± 0.05% to 2.49 ± 0.03% for a planar-mixed heterojunction. PMID:21165074

  11. Carrier dynamics and design optimization of electrolyte-induced inversion layer carbon nanotube-silicon Schottky junction solar cell

    Science.gov (United States)

    Chen, Wenchao; Seol, Gyungseon; Rinzler, Andrew G.; Guo, Jing

    2012-03-01

    Carrier dynamics of the electrolyte-induced inversion layer carbon nanotube-silicon Schottky junction solar cells is explored by numerical simulations. Operation mechanisms of the solar cells with and without the electrolyte-induced inversion layer are presented and compared, which clarifies the current flow mechanisms in a solar cell with an induced inversion layer. A heavily doped back contact layer can behave as a hole block layer. In addition to lowering contact resistance and surface recombination, it is particularly useful for improving carrier separation in an electrolyte-induced inversion layer solar cell or a metal-insulator-semiconductor grating solar cell.

  12. Calibration of particle position on digital holography using transparent resin block with dispersed particles

    Science.gov (United States)

    Tanaka, Y.; Yoshino, T.; Harada, D.; Murata, S.

    2009-11-01

    This paper describes the use of a Calibration Block (CB) for evaluating the accuracy of digital holography in particle position measurement. CB made of acrylic has three layers and the gap between the layers is filled with transparent resin. The refractive index of the resin and the layers is almost the same (1.49). Fin Block (FB), which is not filled with resin, is introduced in order to evaluate effects of the resin. The fringe edges of several holographic patterns are observed by using three kinds of CB and FB. Each layer is coated with spherical particles (diameter: 16.36 ± 0.42 μ m). The influence of multiple scattering on the detected depth of the particles is evaluated by changing the number density of particles. Three kinds of CB and FB are prepared (averaged particle density in the holographic pattern; 83.2, 166.5 and 249.7). The fringe edges of the holographic patterns generated in CB and FB are observed, respectively. It is found that the fringe edges of CB are clearer than FB. Also, Multiple scattering acts as a source of background noise with high spatial frequency, which has almost the same frequency as that of the particle diffraction on the fringe patterns, and reduces the effective signal-to-noise ratio of the holographic pattern. CB can be used to evaluate the influence of multiple scattering on the detected particle depth.

  13. Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

    KAUST Repository

    Karunakaran, Madhavan

    2016-03-11

    In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

  14. Solving block linear systems with low-rank off-diagonal blocks is easily parallelizable

    Energy Technology Data Exchange (ETDEWEB)

    Menkov, V. [Indiana Univ., Bloomington, IN (United States)

    1996-12-31

    An easily and efficiently parallelizable direct method is given for solving a block linear system Bx = y, where B = D + Q is the sum of a non-singular block diagonal matrix D and a matrix Q with low-rank blocks. This implicitly defines a new preconditioning method with an operation count close to the cost of calculating a matrix-vector product Qw for some w, plus at most twice the cost of calculating Qw for some w. When implemented on a parallel machine the processor utilization can be as good as that of those operations. Order estimates are given for the general case, and an implementation is compared to block SSOR preconditioning.

  15. SANS study of three-layer micellar particles

    CERN Document Server

    Plestil, J; Kuklin, A I; Cubitt, R

    2002-01-01

    Three-layer nanoparticles were prepared by polymerization of methyl methacrylate (MMA) in aqueous micellar solutions of poly(methyl methacrylate)-block-poly(methacrylic acid) (PMMA-b-PMA) and polystyrene-block-poly(methacrylic acid) (PS-b-PMA). The resulting polymer forms a layer on the core surface of the original micelles. SANS curves were fitted using an ellipsoidal (PMMA/PMMA/PMA) or spherical (PS/PMMA/PMA) model for the particle core. The particle size (for the presented series of the PMMA/PMMA/PMA particles, the core semiaxes ranged from 87 to 187 A and the axis ratio was about 6) can be finely tuned by variation of monomer concentration. Time-resolved SANS experiments were carried out to describe the growth of the PS/PMMA/PMA particles during polymerization. (orig.)

  16. Quark Neutron Layer Stars

    CERN Document Server

    Carinhas, P A

    1993-01-01

    Typical nuclear equations of state and a quark bag model, surprisingly, allow compact stars with alternate layers of neutrons and quarks. One can determine on the basis of the Gibbs free energy which phase, nuclear or quark, is energetically favorable. Using the nuclear equation of state of Wiringa, and a quark equation of state given by Freedman and McLerran, the allowed quark parameter space for such layer stars is searched. This paper differs from past work in that configurations are found in which quark matter is located exterior and interior to shells of nuclear matter, i.e., dependent on quark parameters, a star may contain several alternating layers of quark and nuclear matter. Given the uncertainty in the quark parameter space, one can estimate the probability for finding pure neutron stars, pure quark stars (strange stars), stars with a quark core and a nucleon exterior, or layer stars. Several layer models are presented. The physical characteristics, stability, and results of a thorough search of th...

  17. Interference layer metallography

    International Nuclear Information System (INIS)

    Refractory metallic materials for application in Gas Cooled High Temperature Reactors are age-hardened nickel or iron base alloys. To control their behaviour and to adapt it to realistic load conditions, these materials have to be subjected to suitable informing tests and characterized. In the past few years, interference layer metallography has proved to be a highly flexible characterization procedure, suitable as an independent investigation method as well as an outstanding way of sample preparation for application of automatic quantitative image analysis to refractory alloys. This paper reports the problems of characterization of the Ni and Fe base alloys to be solved by interference layer metallography and the physical background of this method. The procedure of chromatic contrasting is discussed. From these considerations arises the result that for technical applications the optimum layer material for each special sample should be selected a priori. For that purpose it is necessary to measure the optical constants of the respective structural elements of the alloys as well as those of the candidate layer materials. The measuring procedures are discussed in detail. A routine procedure is deduced which allows to determine a priori the layer material and thickness fitting best to a given problem. (orig.)

  18. Computing the Exponential of Large Block-Triangular Block-Toeplitz Matrices Encountered in Fluid Queues

    OpenAIRE

    Bini, D. A.; Dendievel, S.; Latouche, G.; Meini, B.

    2015-01-01

    The Erlangian approximation of Markovian fluid queues leads to the problem of computing the matrix exponential of a subgenerator having a block-triangular, block-Toeplitz structure. To this end, we propose some algorithms which exploit the Toeplitz structure and the properties of generators. Such algorithms allow to compute the exponential of very large matrices, which would otherwise be untreatable with standard methods. We also prove interesting decay properties of the exponential of a gene...

  19. Backward and forward blocking in human electrodermal conditioning: blocking requires an assumption of outcome additivity.

    Science.gov (United States)

    Mitchell, Chris J; Lovibond, Peter F

    2002-10-01

    Blocking was observed in two human Pavlovian conditioning studies in which colour cues signalled shock. Both forward (Experiment 1) and backward (Experiment 2) blocking was demonstrated, but only when prior verbal and written instructions suggested that if two signals of shock (A+ and B+) were presented together, a double shock would result (AB++). In this case, participants could assume that the outcome magnitude was additive. Participants given non-additivity instructions (A+ and B+ combined would result in the same outcome, a single shock) failed to show blocking. Modifications required for associative models of learning, and normative statistical accounts of causal induction, to account for the impact of additivity instructions on the blocking effect, are discussed. It is argued that the blocking shown in the present experiments resulted from the operation, not of an error-correction learning rule, nor of a simple contingency detection mechanism, but of a more complex inferential process based on propositional knowledge. Consistent with the present data, blocking is a logical outcome of an A+/AB+ design only if participants can assume that outcomes will be additive. PMID:12350284

  20. Simple Examples for Dynamics of a Single Flexible Block

    International Nuclear Information System (INIS)

    Graphite fuel blocks and reflector blocks are major components of a prismatic type HTGR. An earthquake loading on the stacked blocks causes rocking responses and solid impacts between them, and may lead to structural integrity problems. The dynamic analysis of block structures has a long history. A basic understanding of the rocking response of a rigid block resting on a rigid floor had not been well established until when G.W. Housner first presented it in 1963. In 1975, T.H. Lee presented a methodology for analyzing the nonlinear response of a column of stacked prismatic fuel blocks. In 1979 T. Ikushima and T. Nakazawa presented their work results on a seismic analysis of a column of stacked prismatic fuel blocks. A stochastic analysis methodology for a rocking block was introduced by Pol D. Spanos and Aik-Sion Koh. S. J. Hogan considered the dynamics of a slender rigid block mounted on a vibrating rigid table with side walls. Although, several novel methodologies and studies for a single rigid block and stacked rigid blocks have been presented, less attention has been paid to the dynamics of flexible blocks. This paper presents the dynamics and responses of a single flexible block on a vibrating floor, and compares them to the classical ones with a rigid assumption. The numerical model for the single flexible block is from Ref

  1. PhenoBlocks: Phenotype Comparison Visualizations.

    Science.gov (United States)

    Glueck, Michael; Hamilton, Peter; Chevalier, Fanny; Breslav, Simon; Khan, Azam; Wigdor, Daniel; Brudno, Michael

    2016-01-01

    The differential diagnosis of hereditary disorders is a challenging task for clinicians due to the heterogeneity of phenotypes that can be observed in patients. Existing clinical tools are often text-based and do not emphasize consistency, completeness, or granularity of phenotype reporting. This can impede clinical diagnosis and limit their utility to genetics researchers. Herein, we present PhenoBlocks, a novel visual analytics tool that supports the comparison of phenotypes between patients, or between a patient and the hallmark features of a disorder. An informal evaluation of PhenoBlocks with expert clinicians suggested that the visualization effectively guides the process of differential diagnosis and could reinforce the importance of complete, granular phenotypic reporting.

  2. N=1 SUSY Conformal Block Recursive Relations

    CERN Document Server

    Belavin, V A

    2006-01-01

    We present explicit recursive relations for the four-point superconformal block functions that are essentially particular contributions of the given conformal class to the four-point correlation function. The approach is based on the analytic properties of the superconformal blocks as functions of the conformal dimensions and the central charge of the superconformal algebra. The results are compared with the explicit analytic expressions obtained for special parameter values corresponding to the truncated operator product expansion. These recursive relations are an efficient tool for numerically studying the four--point correlation function in Super Conformal Field Theory in the framework of the bootstrap approach, similar to that in the case of the purely conformal symmetry.

  3. Infinite-degree-corrected stochastic block model

    DEFF Research Database (Denmark)

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

    2014-01-01

    In stochastic block models, which are among the most prominent statistical models for cluster analysis of complex networks, clusters are defined as groups of nodes with statistically similar link probabilities within and between groups. A recent extension by Karrer and Newman [Karrer and Newman......, Phys. Rev. E 83, 016107 (2011)] incorporates a node degree correction to model degree heterogeneity within each group. Although this demonstrably leads to better performance on several networks, it is not obvious whether modeling node degree is always appropriate or necessary. We formulate the degree...... corrected stochastic block model as a nonparametric Bayesian model, incorporating a parameter to control the amount of degree correction that can then be inferred from data. Additionally, our formulation yields principled ways of inferring the number of groups as well as predicting missing links...

  4. Neurologic complication after anterior sciatic nerve block.

    Science.gov (United States)

    Shah, Shruti; Hadzic, Admir; Vloka, Jerry D; Cafferty, Maureen S; Moucha, Calin S; Santos, Alan C

    2005-05-01

    The lack of reported complications related to lower extremity peripheral nerve blocks (PNBs) may be related to the relatively infrequent application of these techniques and to the fact that most such events go unpublished. Our current understanding of the factors that lead to neurologic complications after PNBs is limited. This is partly the result of our inability to conduct meaningful retrospective studies because of a lack of standard and objective monitoring and documentation procedures for PNBs. We report a case of permanent injury to the sciatic nerve after sciatic nerve block through the anterior approach and discuss mechanisms that may have led to the injury. Intraneural injection and nerve injury can occur in the absence of pain on injection and it may be heralded by high injection pressure (resistance).

  5. Essential Building Blocks of Human Nature

    CERN Document Server

    Frey, Ulrich J; Willführ, Kai P

    2011-01-01

    To understand why we humans are as we are, it is necessary to look at the essential building blocks that comprise our nature. The foundations of this structure are our evolutionary origins as primates and our social roots. Upon these rest features such as our emotions, language and aesthetic preferences, with our self-perceptions, self-deceptions and thirst for knowledge right at the top. The unifying force holding these blocks together is evolutionary theory. Evolution provides a deeper understanding of human nature and, in particular, of the common roots of these different perspectives. To build a reliable and coherent model of man, leading authors from fields as diverse as primatology, anthropology, neurobiology and philosophy have joined forces to present essays  each describing their own expert perspective. Together they provide a convincing and complete picture of our own human nature.

  6. Osmosis and thermodynamics explained by solute blocking

    CERN Document Server

    Nelson, Peter Hugo

    2016-01-01

    A solute-blocking model is presented that provides a kinetic explanation of osmosis and ideal solution thermodynamics. It validates a diffusive model of osmosis that is distinct from the traditional convective flow model of osmosis. Osmotic equilibrium occurs when the fraction of water molecules in solution matches the fraction of pure water molecules that have enough energy to overcome the pressure difference. Solute-blocking also provides a kinetic explanation for why Raoult's law and the other colligative properties depend on the mole fraction (but not the size) of the solute particles, resulting in a novel kinetic explanation for the entropy of mixing and chemical potential of ideal solutions. Some of its novel predictions have been confirmed, others can be tested experimentally or by simulation.

  7. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  8. BLOCK ITERATIVE METHODS FOR LINEAR ALGEBRAIC EQUATION AND DOMAIN DECOMPOSITION METHOD FOR INCOMPRESSIBLE VISCOUS FLOW

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    It was proved numerically that the Domain Decomposition Method (DDM) with one layer overlapping grids is identical to the block iterative method of linear algebra equations. The results obtained using DDM could be in reasonable aggeement with the results of full-domain simulation. With the three dimensional solver developed by the authors, the flow field in a pipe was simulated using the full-domain DDM with one layer overlapping grids and with patched grids respectively. Both of the two cases led to the convergent solution. Further research shows the superiority of the DDM with one layer overlapping grids to the DDM with patched grids. A comparison between the numerical results obtained by the authors and the experimental results given by Enayet[3] shows that the numerical results are reasonable.

  9. TeraHertz imaging of hidden paint layers on canvas

    OpenAIRE

    Adam, A. J. L.; Planken, P. C. M.; S. Meloni; Dik, J.

    2009-01-01

    We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface, indicating sufficient refractive-index contrast. Our results show that X-rays cannot be used to image through the lead white pigment which effectively blocks the X-rays. Although Infrared Reflectography is...

  10. Earthquakes and large block monumental structures

    Directory of Open Access Journals (Sweden)

    A. Sinopoli

    1995-06-01

    Full Text Available A review of a research program developed in the last fen years into the dynamics of large block structure is presented. The many aspects which characterize the structural behaviour and determine the complexity of the consequent dynamics are briefly discussed. The preliminary mechanical models and first results obtained are also analyzed; they allow to define the direction of the main object of the research in progress.

  11. Blocking a selective association in pigeons.

    OpenAIRE

    Weiss, S J; Panlilio, L V

    1999-01-01

    Experiment 1 demonstrated for the first time a stimulus-reinforcer interaction in pigeons trained with free-operant multiple schedules of reinforcement. Pigeons that treadle pressed in the presence of a tone-light (TL) compound for food exhibited primarily visual stimulus control on a stimulus-element test, whereas pigeons that avoided shock in TL exhibited auditory control. In Experiment 2, this selective association was blocked in pigeons pretrained with the biologically contingency-disadva...

  12. Carbonated concrete blocks for CO2 captation

    OpenAIRE

    Courard, Luc; Parmentier, Véronique; Michel, Frédéric

    2015-01-01

    The CO2 captation process called carbonation, improves specific properties of the concrete during the conversion of carbon dioxide CO2 into calcium carbonate CaCO3. Current environmental concerns motivate the study of carbonation in order to maximize the absorption of carbon dioxide. Moreover, lightweight concrete with bio-based products knows an interesting development in the construction field, especially as thermal insulation panels for walls in buildings. Concrete blocks produced with mis...

  13. Photo-Induced Micellization of Block Copolymers

    OpenAIRE

    Satoshi Kuwayama; Eri Yoshida

    2010-01-01

    We found novel photo-induced micellizations through photolysis, photoelectron transfer, and photo-Claisen rearrangement. The photolysis-induced micellization was attained using poly(4-tert-butoxystyrene)-block-polystyrene diblock copolymer (PBSt-b-PSt). BSt-b-PSt showed no self-assembly in dichloromethane and existed as isolated copolymers. Dynamic light scattering demonstrated that the copolymer produced spherical micelles in this solvent due to irradiation with a high-pressure mercury lamp ...

  14. Self Assembly of Complex Building Blocks

    Science.gov (United States)

    Stucke, David; Crespi, Vincent

    2004-03-01

    A genetic search algorithm for optimizing the packing density of self-assembled multicomponent crystals of nanoparticles applied to complex colloidal building blocks will be presented. The algorithm searches the complex multi-dimensional space to find preferred crystal structures where standard methods fail. Mixtures of colloidal molecules and the structures found to be preferred to phase separation for different species of coloidal molecule mixtures will be shown.

  15. Impedance Matched Absorptive Thermal Blocking Filters

    CERN Document Server

    Wollack, E J; Rostem, K; U-Yen, K

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match $50\\,\\Omega$ and its response has been validated from 0-to-50\\,GHz. The observed return loss in the 0-to-20\\,GHz design band is greater than $20\\,$dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  16. Floating asphalt blocks of the Dead Sea

    Energy Technology Data Exchange (ETDEWEB)

    Nissenbaum, A. (Weizmann Inst. of Science, Rehovot, Israel); Aizenshtat, Z.; Goldberg, M.

    1980-01-01

    Large blocks of mineral matter free (less than 0.1%) asphalt are occasionally found floating on the surface of the Dead Sea. Chemical, spectroscopic and isotopic data are given for the asphalt. The source of the asphalt is not accurately known, but presumably it represents mobilization of heavy viscous asphaltic masses at depth below the lake bottom into the floor of the lake. It may be released to the surface by earth tremors.

  17. Hyperkalemia-induced complete heart block

    Directory of Open Access Journals (Sweden)

    Alireza Baratloo

    2015-05-01

    Full Text Available Background: Potassium, as an extracellular ion, plays an important role in the electrophysiologic function of the myocardium and any change in extracellular concentration of this ion might have a marked impression upon myocyte electrophysiologic gain. High serum potassium levels are thought to impair pulse conduction in Purkinje fibers and ventricles more than that in the Atrioventricular (AV node. Therefore, although complete AV block can occur, it is a rare initial presentation. Case Report: We describe a 62-year-old man with a history of diabetes mellitus, ischemic heart disease and previous Coronary Artery Bypass Graft (CABG, who came to our emergency department due to generalized weakness starting 2 days before admission. The patient also had decreased force in lower limbs, exacerbating from the morning, and was finally diagnosed as a hyperkalemia-induced Complete Heart Block (CHB. It should also be noted that the patient responded dramatically to the administration of 10 mL of 10% calcium gluconate along with external pacing until potassium level correction became effective. Conclusion: In spite of the fact that Hyperkalemia can be associated with frequent Electrocardiogram (ECG abnormality, advanced heart blocks (second- and third-degree AV blocks are usually found only in patients with pre-existing heart failure, conduction abnormalities, or other cardiac diseases. Institution of effective treatment rapidly and forgiveness of traditional non-effective, time consumptive and sometimes risking full-adjustment modalities, such as sodium bicarbonate infusion or exchange resins that prevent their use in the emergent phase, can help minimize patient morbidity and mortality.

  18. Recurrent congenital heart block in neonatal lupus.

    Science.gov (United States)

    Escobar, Maria C; Gómez-Puerta, José A; Albert, Dimpna; Ferrer, Queralt; Girona, Josep

    2007-07-01

    Congenital heart block (CHB) is the main complication of neonatal lupus (NL) and is strongly associated with the presence of anti-SSA/Ro and anti-SSB/La antibodies. The recurrence of CHB in subsequent pregnancies in mothers with these antibodies is uncommon, occurring in approximately 15% of cases. We describe here a case of recurrent CHB in a previously asymptomatic mother with Sjögren syndrome and discuss the current strategies for the prevention and treatment of CHB in NL.

  19. Computation of Boundary Layers

    Directory of Open Access Journals (Sweden)

    József Dénes

    2004-11-01

    Full Text Available This paper is the first part of a series of studies where we examine several methods for the solution of the boundary layer equation of the fluid mechanics. The first of these is the analytical or rather quasi analytical method due to Blasius. This method reduces a system of partial differential equations to a system of ordinary differential equations and these in turn are solved by numerical methods since no exact solution of the Blasius type equations is known. We determind all the Blasius equation neccessary for up to 11-th order approximation. Our further aim to study the finite difference numerical solutions of the boundary layer equation and some of the methods applying weighted residual principles and by comparing these with the ”exact” solutions arrived at by Blasius method develop a quick reliable method for solving the boundary layer equation.

  20. Multicompartment micellar aggregates of linear ABC amphiphiles in solvents selective for the C block: A Monte Carlo simulation

    KAUST Repository

    Zhu, Yutian

    2012-01-01

    In the current study, we applied the Monte Carlo method to study the self-assembly of linear ABC amphiphiles composed of two solvophobic A and B blocks and a solvophilic C block. A great number of multicompartment micelles are discovered from the simulations and the detailed phase diagrams for the ABC amphiphiles with different block lengths are obtained. The simulation results reveal that the micellar structure is largely controlled by block length, solvent quality, and incompatibility between the different block types. When the B block is longer than or as same as the terminal A block, a rich variety of micellar structures can be formed from ABC amphiphiles. By adjusting the solvent quality or incompatibility between the different block types, multiple morphological transitions are observed. These morphological sequences are well explained and consistent with all the previous experimental and theoretical studies. Despite the complexity of the micellar structures and morphological transitions observed for the self-assembly of ABC amphiphiles, two important common features of the phase behavior are obtained. In general, the micellar structures obtained in the current study can be divided into zero-dimensional (sphere-like structures, including bumpy-surfaced spheres and sphere-on-sphere structures), one-dimensional (cylinder-like structures, including rod and ring structures), two-dimensional (layer-like structures, including disk, lamella and worm-like and hamburger structures) and three-dimensional (vesicle) structures. It is found that the micellar structures transform from low- to high- dimensional structures when the solvent quality for the solvophobic blocks is decreased. In contrast, the micellar structures transform from high- to low-dimensional structures as the incompatibility between different block types increases. Furthermore, several novel micellar structures, such as the CBABC five-layer vesicle, hamburger, CBA three-layer ring, wormlike shape with

  1. Stabilizing parquet blocks with epoxy resin

    Directory of Open Access Journals (Sweden)

    S.S. Glazkov

    2015-11-01

    Full Text Available While parquet blocks and panels from stabilized wood show much promise as finishing materials, their widespread use is limited by their low dimensional stability in variable-humidity environments. Existing solutions to stabilize the blocks have several disadvantages, including hard-to-find or toxic stabilizers. This is why this study discusses modifications of epoxy resin which has sufficient functionality for effective structuring. We analyzed the capillary-porous structure of different types of wood, and established the patterns associated with a reduction in the porosity or the specific volume of voids in pine, birch and oak. The basic characteristics of impregnating compositions indicating the high penetrative and structuring capabilities of epoxy resin have been discovered. It is shown that in addition to increasing the strength characteristics, there is a steady decline in water absorption and swelling with an increase in resin content in the wood. It has been found by the method of test fluids that curing the epoxy resin in the presence of hexamethylenediamine is accompanied by a decrease in the proportion of polar components in the total value of the surface tension. Oligomer molecules were shown to penentrate pine wood cells, providing a high moisture protection effect. The results suggest it is possible to use epoxy resin to modify parquet blocks and panels that would be used under variable humidity and high impact loads.

  2. Order and Disorder in Short Block Polymers

    Science.gov (United States)

    Bates, Frank S.

    2015-03-01

    Block polymers have captivated the interest of scientists and engineers for more than half a century. The phase behavior of this class of self-assembling soft material is well understood in the limit of infinite molecular weight, based on the self-consistent mean-field theory pioneered by Leibler. At practical molecular sizes, typically around N ~ 1000 repeat units, fluctuation effects become highly significant in the vicinity of the order disorder transition. One-loop corrections to mean-field theory, first described by Brazovski and applied to block polymers by Fredrickson and Helfand, are not expected to be applicable in this limit. Moreover, the drive towards ever smaller domain dimensions, and the opportunity to circumvent transport limitations associated with entanglements, have motivated experiments with yet lower molecular weight block polymers, N less than 100. This presentation will describe the consequences of fluctuations and the equilibrium structural properties of short model AB diblock polymers in the symmetric (f = 1/2) and asymmetric (f --> 0) regimes above and below the order-disorder transition. The consequences of fluctuations and access to equilibrium states will be described in the 1-dimensional stripped (lamellar) phase and the ordering of point particles in 3-dimensions, respectively. As N --> 1 computer simulation with realistic molecular detail becomes feasible presenting exciting opportunities to compliment the associated theoretical challenges. Research in collaboration with Sangwoo Lee, Chris Leighton and Timothy Gillard and Supported by NSF-DMR-1104368.

  3. Channel blocking of MspA revisited.

    Science.gov (United States)

    Perera, Ayomi S; Wang, Hongwang; Basel, Matthew T; Pokhrel, Megh Raj; Gamage, Pubudu Siyambalagoda; Kalita, Mausam; Wendel, Sebastian; Sears, Bryan; Welideniya, Dhanushi; Liu, Yao; Turro, Claudia; Troyer, Deryl L; Bossmann, Stefan H

    2013-01-01

    Porin A from Mycobacterium smegmatis (MspA) is a highly stable, octameric channel protein, which acts as the main transporter of electrolytes across the cell membrane. MspA features a narrow, negatively charged constriction zone, allowing stable binding of various analytes thereby blocking the channel. Investigation of channel blocking of mycobacterial porins is of significance in developing alternate treatment methods for tuberculosis. The concept that ruthenium(II)quaterpyridinium complexes have the capability to act as efficient channel blockers for MspA and related porins, emerged after very high binding constants were measured by high-performance liquid chromatography and steady-state luminescence studies. Consequently, the interactions between the ruthenium(II) complex RuC2 molecules and MspA, leading to RuC2@MspA assemblies, have been studied utilizing time-resolved absorption/emission, atomic force microscopy, dynamic light scattering, ζ potential measurements, and isothermal titration calorimetry. The results obtained provide evidence for the formation of clusters/large aggregates of RuC2 and MspA. The results are of interest with respect to utilizing prospective channel blockers in porins. The combination of results from conceptually different techniques shed some light onto the chemical nature of MspA-channel blocker interactions thus contributing to the development of a paradigm for channel blocking. PMID:23214433

  4. Modelling of multi-block data

    DEFF Research Database (Denmark)

    Høskuldsson, Agnar; Svinning, K.

    2006-01-01

    Here is presented a unified approach to modelling multi-block regression data. The starting point is a partition of the data X into L data blocks, X = (X-1, X-2,...X-L), and the data Y into M data-blocks, Y = (Y-1, Y-2,...,Y-M). The methods of linear regression, X -> Y, are extended to the case...... of a linear relationship between each X-i and Y-j. X-i -> Y-j. A modelling strategy is used to decide if the residual X-i should take part in the modelling of one or more Y(j)s. At each step the procedure of finding score vectors is based on well-defined optimisation procedures. The principle of optimisation...... is based on that the score vectors should give the sizes of the resulting Y(j)s loading vectors as large as possible. The partition of X and Y are independent of each other. The choice of Y-j can be X-j, Y-i = X-i, thus including the possibility of modelling X -> X-i,i=1,...,L. It is shown how...

  5. Block Storage Service: Status and Performance

    CERN Document Server

    Van der Ster, Daniel

    2014-01-01

    This memo summarizes the current status of the Ceph block storage service as it is used for OpenStack Cinder Volumes and Glance Images as of May 2014. We present the block storage activity on the current cluster, measuring IOPS and latencies, and present a cost/benefit analysis of using SSDs to optimize the cost and performance efficiency of the service. During tests in collaboration with IT-CF, we have concluded that by adding SSDs as the synchronous write journals (used to guarantee data durability), we are able increase the IOPS capacity by 4-5 times, at a cost of decreasing the available volume by 20%. Further, the testing has shown that the Ceph implementation is able to operate at the limit of the hardware performance; software-induced performance limitations were not yet observed in either the spinning disk or SSD configurations. In addition, we believe that increasing small write performance with SSDs is applicable only to the block storage use-case; high-bandwidth use-cases such as physics data stora...

  6. Active Block Layout: A High Performance Block Layout Mechanism%Active Block Layout:一种高性能磁盘布局机制

    Institute of Scientific and Technical Information of China (English)

    卢军; 卢显良; 罗光春; 韩宏; 魏青松

    2003-01-01

    The access frequency of different files in file system is dissimilar. If file system can optimize the block lay-out of these hot files which are frequently accessed,the performance of file system will be improved. This paper pre-sents a high performance block layout mechanism: Active Block Layout (ABL). ABL can record the access frequencyof every file in file system and actively optimize the block layout of these hot files by block duplicating. The duplicatedblocks can be placed in the special zone of track,which is called "Cooling Zone". ABL can automatically determine theplacing position and the copy count of the blocks which need to be duplicated. In order to reduce the overhead of blockduplication,this paper also presents a mechanism which uses the potential disk bandwidth to realize the block duplica-tion,and does not obviously degrade the performance of file system.

  7. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  8. Association of anionic surfactant and physisorbed branched brush layers probed by neutron and optical reflectometry

    OpenAIRE

    Liu, Xiaoyan; Dédinaité, Andra; Nylander, Tommy; Dabkowska, Aleksandra P.; Skoda, Maximilian; Makuska, Ricardas; Claesson, Per Martin

    2015-01-01

    Pre-adsorbed branched brush layers were formed on silica surfaces by adsorption of a diblock copolymer consisting of a linear cationic block and an uncharged bottle-brush block. The charge of the silica surface was found to affect the adsorption, with lower amounts of the cationic polyelectrolyte depositing on less charged silica. Cleaning under basic conditions rendered surfaces more negatively charged (more negative zeta-potential) than acid cleaning and was therefore used to increase polye...

  9. A POCS-Based Algorithm for Blocking Artifacts Reduction

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi-hong; CHENG Guo-hua; YU Song-yu

    2006-01-01

    An algorithm for blocking artifacts reduction in DCT domain for block-based image coding was developed. The algorithm is based on the projection onto convex set (POCS) theory. Due to the fact that the DCT characteristics of shifted blocks are different caused by the blocking artifacts, a novel smoothness constraint set and the corresponding projection operator were proposed to reduce the blocking artifacts by discarding the undesired high frequency coefficients in the shifted DCT blocks. The experimental results show that the proposed algorithm outperforms the conventional algorithms in terms of objective quality, subjective quality, and convergence property.

  10. Rapid self-assembly of block copolymers to photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

    2016-07-05

    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  11. Magmatic and tectonic evolution of the Ladakh Block from field studies

    Science.gov (United States)

    Raz, U.; Honegger, K.

    1989-04-01

    The Ladakh Block is in an intermediate position between the Indian plate in the south and the Karakorum-Tibetan plate in the north. To the west it is separated from the Kohistan Arc by the Nanga Parbat Syntaxis, to the east it is cut off from the Lhasa Block by the Gartok-Nubra Fault. Present data, together with previously published results, show, that the Ladakh Block consists of an island arc in the south and a calc-alkaline batholith in the north with remnants of a continental crust. Migmatitic gneisses and metasedimentary sequences, such as quartzites and metapelites, interbedded with basaltic volcanics and overlain by thick platform carbonates were found as evidence of a continental crust. Remnants of megafossils ( Megalodon and Lithiotis) within the high-grade metamorphic marbles indicate a probable age of Late Triassic to Early Jurassic. These sediments were intruded by a faintly layered hornblende-gabbro, which preceded the calc-alkaline magmatic episode. Gabbro and gabbronorites are found as roof pendants and large inclusions within diorites and granodiorites. The major part of the batholith consists of granodiorite and biotite-granite plutons, ranging from Late Cretaceous to Tertiary. Associated with the intrusives are volcanic rocks with trachyandesite to alkalibasalt and basalt-andesite to rhyolite compositions. Garnet-bearing leucogranites succeeded the emplacement of the major plutons. The magmatic stage ended, finally, by intense fracturing and injections of NE-SW striking andesitic dykes. The southernmost unit of the Ladakh Block is formed by oceanic crust with serpentinized peridotite and hornblende-gabbro and is covered by volcanics of an island-arc type (Dras volcanics). These units are intruded by gabbronorite, as well as Middle and Upper Cretaceous granodiorite and coarse-grained biotite-granite. In a plate tectonic view the Ladakh Block represents a transitional sector between the pure island arc of Kohistan in the west and the Andean type

  12. Computing Aerodynamic Performance of a 2D Iced Airfoil: Blocking Topology and Grid Generation

    Science.gov (United States)

    Chi, X.; Zhu, B.; Shih, T. I.-P.; Slater, J. W.; Addy, H. E.; Choo, Yung K.; Lee, Chi-Ming (Technical Monitor)

    2002-01-01

    The ice accrued on airfoils can have enormously complicated shapes with multiple protruded horns and feathers. In this paper, several blocking topologies are proposed and evaluated on their ability to produce high-quality structured multi-block grid systems. A transition layer grid is introduced to ensure that jaggedness on the ice-surface geometry do not to propagate into the domain. This is important for grid-generation methods based on hyperbolic PDEs (Partial Differential Equations) and algebraic transfinite interpolation. A 'thick' wrap-around grid is introduced to ensure that grid lines clustered next to solid walls do not propagate as streaks of tightly packed grid lines into the interior of the domain along block boundaries. For ice shapes that are not too complicated, a method is presented for generating high-quality single-block grids. To demonstrate the usefulness of the methods developed, grids and CFD solutions were generated for two iced airfoils: the NLF0414 airfoil with and without the 623-ice shape and the B575/767 airfoil with and without the 145m-ice shape. To validate the computations, the computed lift coefficients as a function of angle of attack were compared with available experimental data. The ice shapes and the blocking topologies were prepared by NASA Glenn's SmaggIce software. The grid systems were generated by using a four-boundary method based on Hermite interpolation with controls on clustering, orthogonality next to walls, and C continuity across block boundaries. The flow was modeled by the ensemble-averaged compressible Navier-Stokes equations, closed by the shear-stress transport turbulence model in which the integration is to the wall. All solutions were generated by using the NPARC WIND code.

  13. Many-body localization: construction of the emergent local conserved operators via block real-space renormalization

    Science.gov (United States)

    Monthus, Cécile

    2016-03-01

    A fully many-body localized (FMBL) quantum disordered system is characterized by the emergence of an extensive number of local conserved operators that prevents the relaxation towards thermal equilibrium. These local conserved operators can be seen as the building blocks of the whole set of eigenstates. In this paper, we propose to construct them explicitly via block real-space renormalization. The principle is that each renormalization group step diagonalizes the smallest remaining blocks and produces a conserved operator for each block. The final output for a chain of N spins is a hierarchical organization of the N conserved operators with ≤ft(\\frac{\\ln N}{\\ln 2}\\right) layers. The system size nature of the conserved operators of the top layers is necessary to describe the possible long-range order of the excited eigenstates and the possible critical points between different FMBL phases. We discuss the similarities and the differences with the strong disorder RSRG-X method that generates the whole set of the 2 N eigenstates via a binary tree of N layers. The approach is applied to the long-range quantum spin-glass Ising model, where the constructed excited eigenstates are found to be exactly like ground states in another disorder realization, so that they can be either in the paramagnetic phase, in the spin-glass phase or critical.

  14. Effect of Phase Change Materials (PCMs Integrated into a Concrete Block on Heat Gain Prevention in a Hot Climate

    Directory of Open Access Journals (Sweden)

    Ahmad Hasan

    2016-10-01

    Full Text Available In the current study, a phase change material (PCM contained in an insulated concrete block is tested in extremely hot weather in the United Arab Emirates (UAE to evaluate its cooling performance. An insulated chamber is constructed behind the block containing PCM to mimic a scaled down indoor space. The effect of placement of the PCM layer on heat gain indoors is studied at two locations: adjacent to the outer as well as the inner concrete layer. The inclusion of PCM reduced heat gain through concrete blocks compared to blocks without PCM, yielding a drop in cooling load indoors. The placement of PCM and insulation layers adjacent to indoors exhibited better cooling performance compared to that adjacent to the outdoors. In the best case, a temperature drop of 8.5% and a time lag of 2.6 h are achieved in peak indoor temperature, rendering a reduction of 44% in the heat gain. In the tested hot climate, the higher ambient temperature and the lower wind speed hampered heat dissipation and PCM re-solidification by natural ventilation. The findings recommend employing a mechanical ventilation in hot climates to enhance regeneration of the PCM to solid state for its optimal performance.

  15. Layer-Cake Earth

    Science.gov (United States)

    Tedford, Rebecca; Warny, Sophie

    2006-01-01

    In this article, the authors offer a safe, fun, effective way to introduce geology concepts to elementary school children of all ages: "coring" layer cakes. This activity introduces the concepts and challenges that geologists face and at the same time strengthens students' inferential, observational, and problem-solving skills. It also addresses…

  16. Layered pavement systems

    Science.gov (United States)

    Numerous aspects of the mechanical and structural response of layered pavement systems are discussed. Subgrade moduli for soil that exhibits nonlinear behavior are predicted. The use of a pressure meter test to predict modulus is discussed. Load equivalency factors of triaxial loading for flexible pavements is discussed, as well as a constitutive equation for the permanent strain of sand subjected to cyclic loading.

  17. Physical Layer Network Coding

    DEFF Research Database (Denmark)

    Fukui, Hironori; Yomo, Hironori; Popovski, Petar

    2013-01-01

    Physical layer network coding (PLNC) has the potential to improve throughput of multi-hop networks. However, most of the works are focused on the simple, three-node model with two-way relaying, not taking into account the fact that there can be other neighboring nodes that can cause...

  18. EHD lubricating layer

    Energy Technology Data Exchange (ETDEWEB)

    Shvarts, I.A.

    1978-01-01

    The simplest model of an EHD lubricating layer consists of a unipolarly charged nonconducting viscous fluid between two parallel or slightly inclined nonconducting plates. The performance of such a layer is analyzed here on the basis of the fundamental EHD equations, with a plane-parallel approximation of the flow of a thin layer under a variable upper boundary. The results of the solution indicate that the bearing capacity of such a layer between parallel plates does not depend on the viscosity of the fluid, but is proportional to the energy density of the electric field in vacuum. With the plates not parallel, the bearing capacity depends on the mobility and the diffusion of the charged fluid particles. In either case the energy of the electric field can be made to compensate for the energy dissipation due to viscous friction, and in this case or with overcompensation such as EHD bearing becomes an EHD generator. Most valuable for practical applications are fluids with a high dielectric permittivity, such as ammonia and hydrogen chloride at cryogenic temperatures. 5 references, 1 figure.

  19. MITRE sensor layer prototype

    Science.gov (United States)

    Duff, Francis; McGarry, Donald; Zasada, David; Foote, Scott

    2009-05-01

    The MITRE Sensor Layer Prototype is an initial design effort to enable every sensor to help create new capabilities through collaborative data sharing. By making both upstream (raw) and downstream (processed) sensor data visible, users can access the specific level, type, and quantities of data needed to create new data products that were never anticipated by the original designers of the individual sensors. The major characteristic that sets sensor data services apart from typical enterprise services is the volume (on the order of multiple terabytes) of raw data that can be generated by most sensors. Traditional tightly coupled processing approaches extract pre-determined information from the incoming raw sensor data, format it, and send it to predetermined users. The community is rapidly reaching the conclusion that tightly coupled sensor processing loses too much potentially critical information.1 Hence upstream (raw and partially processed) data must be extracted, rapidly archived, and advertised to the enterprise for unanticipated uses. The authors believe layered sensing net-centric integration can be achieved through a standardize-encapsulate-syndicateaggregate- manipulate-process paradigm. The Sensor Layer Prototype's technical approach focuses on implementing this proof of concept framework to make sensor data visible, accessible and useful to the enterprise. To achieve this, a "raw" data tap between physical transducers associated with sensor arrays and the embedded sensor signal processing hardware and software has been exploited. Second, we encapsulate and expose both raw and partially processed data to the enterprise within the context of a service-oriented architecture. Third, we advertise the presence of multiple types, and multiple layers of data through geographic-enabled Really Simple Syndication (GeoRSS) services. These GeoRSS feeds are aggregated, manipulated, and filtered by a feed aggregator. After filtering these feeds to bring just the type

  20. Detailed analysis of bathocuproine layer for organic solar cells based on copper phthalocyanine and C60

    Science.gov (United States)

    Huang, Jiang; Yu, Junsheng; Lin, Hui; Jiang, Yadong

    2009-04-01

    The electrical characteristics of double heterojunction organic solar cells with various thicknesses of bathocuproine (BCP) as an exciton-blocking layer (EBL) were studied. A theoretical analysis using optical transfer matrix theory was carried out to obtain insight into how the EBL influences light-absorbing and exciton-transporting properties in the organic layers. The results showed that by employing an 8-10 nm BCP layer exciton density was increased by 46%. By using an improved equivalent circuit model, photovoltaic characteristics were parametrized and modeled, which revealed that the thin BCP layer solar cells was also discussed.