Bottom Pole Research Articles

A tough Janus poly(vinyl alcohol)-based hydrogel for wound closure and anti postoperative adhesion

Traditional adhesive hydrogels perform well in tissue adhesion but they fail to prevent postoperative tissue adhesion. To address this challenge, a biodegradable Janus adhesive hydrogel (J-AH) was designed and fabricated by the assembly of three different functional layers including anti-adhesive layer, reinforceable layer, and wet tissue adhesive layer. Each layer of J-AH serves a specific function: the top zwitterionic polymeric anti-adhesive layer shows superior resistance to cell/protein and tissue adhesion; the middle poly(vinyl alcohol)/tannic acid reinforceable matrix layer endows the hydrogel with good mechanical toughness of ∼2.700 MJ/m3; the bottom poly(acrylic acid)/polyethyleneimine adhesive layer imparts tough adhesion (∼382.93 J/m2 of interfacial toughness) to wet tissues. In the rat liver and femoral injury models, J-AH could firmly adhere to the bleeding tissues to seal the wounds and exhibit impressive hemostatic efficiency. Moreover, in the in vivo adhesion/anti-adhesion assay of J-AH between the defected cecum and peritoneal walls, the top anti-adhesive layer can effectively inhibit undesired postoperative abdominal adhesion and inflammatory reaction. Therefore, this research may present a new strategy for the design of advanced bio-absorbable Janus adhesive hydrogels with multi-functions including tissue adhesion, anti-postoperative adhesion and biodegradation. Statement of significanceDespite many adhesive hydrogels with tough tissue adhesion capability have been reported, their proclivity for undesired postoperative adhesion remains a serious problem. The postoperative adhesion may lead to major complications and even endanger the lives of patients. The injectable hydrogels can cover the irregular wound and suppress the formation of postoperative adhesion. However, due to the lack of adhesive properties with tissue, it is difficult for the hydrogels to maintain on the wound surface, resulting in poor anti-postoperative adhesion effect. Herein, we design a Janus adhesive hydrogel (J-AH). J-AH integrates together robust wet tissue adhesion and anti-postoperative adhesion. Therefore, this research may present a new strategy for the design of advanced bio-absorbable Janus adhesive hydrogels.

PH-tailored activated water reservoir for rapid solar water purification via dual-layer hydrogel architecture

Solar vapor generation is a facile and effective approach to harvest pure water from seawater and polluted water, and diverse of materials or microstructure tuning methods have been reported to promote the evaporation rate. Nevertheless, the vapor yield via current solar water purification technology is limited due to high water evaporation enthalpy arising from the strong intermolecular hydrogen bonds. In this study, we advanced the solar evaporator architecture by adding another activated water reservoir beneath it. As such, the bottom poly (acrylic acid-co-acrylamide) (PAA-AM) layer could supply ample activated water (reduced evaporation enthalpy) to the top layer for solar water evaporation due to the increased intermediate water. By tuning the microstructure of PAA-AM bottom-layer with pH, the optimal dual-layer hydrogel evaporator presents a superior water evaporation rate of 2.79 kg m−2h−1 under one sun, 62.2 % enhancement compared with the single-layer PPy@PAA-AM solar evaporator (formed by in situ polymerization of pyrrole in the PAA-AM hydrogel). We demonstrated the strategy was applicable to other single-layer evaporators. The fabricated flexible dual-layer hydrogel evaporator was employed for real seawater desalination and water purification from polluted solutions, manifesting great possibility for the deployment to alleviate the water scarcity crisis, particularly for the economically stressed communities.

Aspartate all-in-one doping strategy enables efficient all-perovskite tandems.

All-perovskite tandem solar cells hold great promise in surpassing the Shockley-Queisser limit for single-junction solar cells1-3. However, the practical use of these cells is currently hampered by the subpar performance and stability issues associated with mixed tin-lead (Sn-Pb) narrow-bandgap perovskite subcells in all-perovskite tandems4-7. In this study, we focus on the narrow-bandgap subcells and develop an all-in-one doping strategy for them. We introduce aspartate hydrochloride (AspCl) into both the bottom poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) and bulk perovskite layers, followed by another AspCl posttreatment. We show that a single AspCl additive can effectively passivate defects, reduce Sn4+ impurities and shift the Fermi energy level. Additionally, the strong molecular bonding of AspCl-Sn/Pb iodide and AspCl-AspCl can strengthen the structure and thereby improve the stability of Sn-Pb perovskites. Ultimately, the implementation of AspCl doping in Sn-Pb perovskite solar cells yielded power conversion efficiencies of 22.46% for single-junction cells and 27.84% (27.62% stabilized and 27.34% certified) for tandems with 95% retention after being stored in an N2-filled glovebox for 2,000 h. These results suggest that all-in-one AspCl doping is a favourable strategy for enhancing the efficiency and stability of single-junction Sn-Pb perovskite solar cells and their tandems.

Simultaneously enhancing purification, catalysis and in situ separation in a continuous cross-flow catalytic degradation process of multi-component organic pollutants by a double-layer PVDF composite membrane

Organic pollutant degradation of waterbody by membrane catalysis is widely reported due to the low operation cost and high catalytic degradation efficiency. However, it still faces a great challenge to effectively treat the complicated wastewater with coexisting multi-component organic pollutants. Herein, we design and then fabricate a novel double-layer composite membrane to realize the separation of multi-component organic pollutants, selectively catalytic degradation and in situ product separation in a one-step. This double-layer membrane systematically characterized by FTIR, XPS, SEM, AFM and the other techniques, comprises a top semi- interpenetrating polymer network(semi-IPN) layer and a bottom poly(vinylidene fluoride)-Pd catalytic layer. In a continuous cross-flow filtration process, some pollutants such as congo red, direct black 38, direct red 23 and BSA are directly separated by the membrane, while the pollutant p-nitrophenol controllably penetrates through the top semi-IPN layer and then reacts in the catalytic layer; subsequently, the product p-aminophenol is in situ separated and collected. In this process, the pollutant p-nitrophenol is purified by filtration in advance; further, the product is isolated by the top layer and timely dischared out by penetrative flow. Therefore, this process prevents the undesired pollutants and products from interfering the catalytic degradation of the catalytic layer. Thus, degradation reaction can continuously and conveniently proceed, companying with products in situ separation and collection.

Wise-Pattern Superomedial Dermoglandular Pedicle Technique: Improves Breast Upper Pole Fullness and Breast Proportions.

Background: This study aimed to analyze postoperative upper pole fullness, upper/lower pole ratios, bottoming-out deformity, and complication rates for patients who underwent planned bilateral reduction mammoplasty for gigantomastia using the superomedial dermoglandular pedicle technique and Wise-pattern skin excision. Methods: A total of 105 consecutive patients were evaluated postoperatively within a year in full lateral position, and the upper pole was between the lines drawn horizontally from the nipple meridian, where the breast became evident on the chest wall. Flat and slightly convex upper pole slopes were considered well-rounded; the concave ones were evaluated as exhibiting decreased fullness. The lower pole was the height between the horizontal line passing through the level of the inframammary fold and nipple meridian. Bottoming-out deformity was evaluated according to the 45/55% ratio developed by Mallucci and Branford, where the bottom pole was above 55%, at which it was held to be leaning toward bottoming-out deformity. Results: The upper and lower pole ratios were 44.79% ± 2.80% and 55.21% ± 2.80%, respectively. In 4 cases, a lower pole distance of >55% was leaning toward bottoming-out deformity. A minimum of 12 months was required after surgery to detect upper pole fullness and any possible bottoming-out deformity. The upper pole fullness was achieved in 94% of cases that underwent superomedial dermoglandular pedicle Wise-pattern breast reduction. Conclusion: The use of the superomedial dermoglandular pedicle technique with the Wise-pattern in breast reduction operations helps in ensuring upper pole fullness, resulting in less bottoming-out deformity and requiring less revision.

Bioinspired Superhydrophobic Thermochromic Films with Robust Healability.

Thermochromic films with intriguing functionalities have great potential in soft actuators, heat storage devices, and interactive interface sensors. Inspired by the unique features of bird feathers (such as Nicobar pigeon, Anna hummingbird, mandarin duck, etc.), a superhydrophobic thermochromic film (STF) with robust healability is proposed for the first time through sandwiching an electric heater between a top thermochromic layer and a bottom poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) substrate. The STF exhibits fast and reversible color conversions of blue-pink-yellow under a low input power and has a superhydrophobic property with a contact angle of 155°. Furthermore, owing to the strong dynamic dipole-dipole interactions between the polar CF3 groups of flexible PVDF-HFP chains, the STF possesses a robust healing capability of structure and conductivity. By means of the temperature difference generated by the objects contacting (finger, iron, and water) as a stimulus, the STFs achieve tactile imaging and writing record with advantages of transient display, automatic erasure, and excellent reusability. Additionally, the STF-based anti-counterfeiting security labels with superhydrophobicity and three-state color switching simultaneously realize facile distinguishment and difficult forgery. The findings conceivably stand out as a new methodology to fabricate functional thermochromic materials for innovative applications.

Abdominal aortic aneurysm and horseshoe kidney-open surgical repair: A case report

Introduction. Horseshoe kidney (HSK) is a congenital anomaly of embryonic kidneys, which occurs in early gestation when both kidneys are in close proximity. This hap-pens as a result of abnormal migration of nephrogenic cells. The presence of HSK may complicate an anterior approach to reconstructive surgery of the aorta and iliac vessels because the isthmus of the HSK lies across the aorta. HSK is often associated with anomalous renal vessels. Case report. A 71-year-old female patient was admit-ted with an abdominal aortic aneurysm, 50 mm in diameter, and HSK, and multiple aberrant renal vessels with subocluded upper left renal artery as seen on the multidetector computed tomography (MDCT). Open surgical treatment was applied. Endarterectomy of the left upper renal artery, perfusion of the right common bottom pole renal artery, and reimplantation of both bottom polar renal arteries were done. Isthmus was not divided. The co-existence of HSK and abdominal aortic aneurysm (AAA) is a rare condition. It presents a technical challenge to vascular surgeons because the surgical treatment of such an aneurysm is complicated due to the abnormal anatomy, difficulties in exposing the aneurysm, and a variable blood supply to the isthmus and lower poles of the HSK. Conclusion. Open surgical repair of AAA with HSK is a successful method and provides good exposure, the possibility of renal circulation preservation, and prevention of renal insufficiency.

Organic-inorganic hybrid perovskite quantum dot light-emitting diodes using a graphene electrode and modified PEDOT:PSS.

Perovskite quantum dot (PQD) light-emitting diodes (LEDs) have rapidly developed in the past several years due to the excellent optoelectronic properties of lead halide perovskites. However, PQD LEDs using graphene electrodes have not been reported despite their huge potential for applications in flexible displays and lighting sources. Herein, graphene was first used as the electrode of PQD LEDs. To overcome graphene's limitations such as hydrophobicity and graphene-induced film nonuniformity, the modification of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with Triton X-100 and dimethyl sulfoxide (DMSO) codoping was reported, which not only improved the wettability of the graphene surface and the sequent film quality, but also reduced the dissolution of the PQD solvent to the bottom poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)-benzidine] and PEDOT:PSS. More importantly, the synergistic effect of Triton X-100 and DMSO altered the PEDOT:PSS morphology from a coiled structure to a nanofibril conductive network, sufficiently enhancing the electrical conductivity of PEDOT:PSS. With this modification strategy, green PQD LEDs with CH3NH3PbBr3 emission layers were successfully fabricated on graphene anodes, with 3.7- and 4.4-fold enhancements in luminance and current efficiency, respectively, compared to those of their counterparts without PEDOT:PSS modification. The film modification strategy and graphene-based PQD LEDs in this work are expected to shed light on the further design and manufacture of flexible highly efficient PQD display and lighting devices.

Polymer brushes modified by photosensitive azobenzene containing polyamines

Abstract This paper describes a strategy for preparing photosensitive polymeric grafts on flat solid surfaces by loading diblock-copolymer or homopolymer brushes with cationic azobenzene-containing surfactants. In contrast to previous work, we utilize photosensitive surfactants that bear positively-charged polyamine head groups whose charge varies between 1+ and 3+. Poly(methylmethacrylate-b-methacrylic acid) (PMMA-b-PMAA) brushes were prepared by employing atom transfer radical polymerization, where the bottom poly(methyl methacrylate) block was grown first followed by the synthesis of t-butyl methacrylate block that after de-protection yielded poly(methacrylic acid). We used PMMA-b-PMAA brushes with constant grafting density and length of the PMMA block, and three different lengths of the PMAA block. The azobenzene-based surfactants attached only to the PMAA block. The degree of binding (i.e., the number of surfactant molecules per binding site on the brush backbone) of the surfactants to the brush depends strongly on the valence of the surfactant head-group; within the brushes the concentration of the surfactant carrying unit charge is larger than that of multivalent surfactants. We detect pronounced response of the brush topography on irradiation with UV interference pattern even at very low degree of binding (as small as 0.08) of multi-valence surfactant. Areas on the sample that receive the highest UV dose exhibit chain scission. By removing the ruptured chains from the substrate via good solvent, one uncovers a surface topographical relief grating, whose spatial arrangement follows the intensity distribution of the UV light on the sample during irradiation. Due to strong coupling of the multi-valence surfactants to the polymer brush, it was possible in some cases to completely remove the polyelectrolyte block from the PMMA layer. The application of multi-valence azobenzene surfactants for triggering brush photosensitive has important advantage over usage of surfactant with unit charge because relative to single-valence surfactants much lower concentrations of the multivalent surfactant are needed to achieve comparable response upon UV irradiation.

Solution-processed organic trilayer solar cells incorporating conjugated polyelectrolytes

We report solution-processed organic trilayer solar cells consisting of a bottom poly(3-hexylthiophene) (P3HT) layer, a conjugated polyelectrolyte (CPE) interlayer and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) top layer, wherein the CPE exists as an interlayer within the donor–acceptor junction. The influence of interlayer thickness on device properties was investigated, as well as the behavior of molecular dipoles in the trilayer solar cells when influenced by external electrical stimuli. We found that incorporation of an interlayer which is too thick results in decreased performance due to reduced short-circuit current (JSC), open-circuit voltage (VOC), and fill factor (FF). However the VOC is found to increase significantly when a thin CPE layer is used in conjunction with an external electric field. These results provide an experimental approach to probe the influence of interfacial dipoles on the solar cell parameters and behavior of charge separating organic donor/acceptor junctions, yielding fundamental information about the influence of electrical dipoles on the donor/acceptor interface in organic solar cells.

Allocation of Attention during Tasks Involving Discriminations of Rotated Stimuli

Event Abstract Back to Event Allocation of Attention during Tasks Involving Discriminations of Rotated Stimuli Jordan Searle1* and Jeff Hamm1 1 University of Auckland, School of Psychology, New Zealand Participants were assigned to one of three tasks, namely to determine if a dot was located at the top or bottom pole of a rotated object, to determine if a rotated object would face to the left or right if imagined at the upright, or to determine if a rotated letter was in its mirrored or normal version. EEG was employed to investigate how attention is initially allocated to the stimuli in each task. Directing attention to task-relevant lateralized visual information is known to produce an N2pc component. For decisions regarding the location of a dot at the top or bottom pole of a rotated object, the analysis of ERPs to lateralized locations of the dots revealed the presence of an early posterior contralateral negativity. Further analysis of ERPs for this task, this time to lateralized locations of the fronts of the objects, revealed the presence of an N2pc component. For decisions regarding the direction in which a rotated object was facing, the analysis of ERPs to lateralized locations of the fronts of objects also revealed the presence of an N2pc component. Finally, for decisions regarding whether rotated letters were mirrored or normal, the analyses of ERPs to lateralized locations of the tops of letters or to lateralized locations of the letters' distinguishing features revealed little evidence to suggest the presence of lateralized attention. These results indicate that early visual processing is adapted to the needs of the decision that is required of the task. Keywords: Attention, Visual Perception, EEG, ERPs, object processing Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Attention Citation: Searle J and Hamm J (2015). Allocation of Attention during Tasks Involving Discriminations of Rotated Stimuli. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00314 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Ms. Jordan Searle, University of Auckland, School of Psychology, Auckland, New Zealand, jsea025@aucklanduni.ac.nz Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Jordan Searle Jeff Hamm Google Jordan Searle Jeff Hamm Google Scholar Jordan Searle Jeff Hamm PubMed Jordan Searle Jeff Hamm Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

On nonlinear dynamics behavior and control of a new model of a magnetically levitated vibrating system, excited by an unbalanced DC motor of limited power supply

We analyze new results on a magnetically levitated body (a block including a magnet whose bottom pole is set in such a way as to repel the upper pole of a magnetic base) excited by a non-ideal energy source (an unbalanced electric motor of limited power supply). These new results are related to the jump phenomena and increase of power required of such sources near resonance are manifestations of a non-ideal system and they are referred as the Sommerfeld effect, which emulates an energy sink. In this work, we also discuss control strategies to be applied to this system, in resonance conditions, in order to decrease its vibration amplitude and avoiding this apparent energy sink.

Improvement of Bottom Oxide Thickness Scaling of Inter-Poly Dielectric by Floating Gate Top Plasma Nitridation

This letter concerns the electrical properties of floating gate (FG) that has undergone top nitridation, used in NAND flash memory devices As the dimensions are scaled down to 5 nm and beyond, the use of a thinner inter-poly dielectric (IPD) can provide the required gate coupling ratio, leaving more room for the control gate poly filling between the FG. However, the effect of the IPD scaling on data retention capability is the main bottleneck. Two interesting retention failure phenomena are demonstrated in a sample of thin bottom poly oxide (BPO). They are attributed to the enhanced degradation of the electrical field at the top corners of the FG and the potential difference between neighboring FG along the WL direction. These phenomena must be taken into consideration while setting the limits of the BPO in the IPD film scheme. The proposed FG top nitridation overcomes this limitation on the thinning of the bottom oxide improving the data retention characteristics of NAND flash memory devices.

Analysis on electrostatic behavior of a conducting prolate spheroid under an electric field

This paper presents the electrostatic analysis of a conducting prolate spheroid under an external electric field in axisymmetric configurations. The configurations consist of a conducting spheroid which is in contact with or separated from a grounded plane. We apply the method of images using multipoles to the electric field calculation. The calculation uses the multipole re-expansion formulae and the equivalent image charges of a prolate conducting spheroid. The induced charge and force are determined from the multipole images. For a spheroid on the grounded plane, the calculation results show that the maximal field increases nonlinearly with the major-to-minor axis ratio of the spheroid. The charge and the force are compared between the spheroids of the same major axis or the same surface area. We propose empirical formulae for approximating the maximal field, charge and force with the errors smaller than 2% for the axis ratio between 1 and 32. We examine the propriety of the approximation of the electric field, charge and force based on a hemispheroidal model. For an uncharged spheroid separated from the grounded plane, we clarify the relationship between the separation and the field intensification at the bottom pole of the spheroid. Based on the critical field strength of a background medium, the position of the spheroid where the partial discharge takes place is estimated. For a charged spheroid, we found that the maximal electric field hardly depends on the separation from the plane.

Strain imaging of magnetic domain structures in the magnetic head of a hard disk drive

AbstractDetection and imaging of magnetic‐field‐induced strains using scanning probe microscopy enable us to observe magnetic domain structures. Domain structures in a magnetization reversal process of the lateral‐recording head in a hard disk drive were investigated by scanning over the air‐bearing surface of the head. External magnetic fields were applied by the writing coil. In the process, magnetic domains in the bottom pole were divided into right and left regions in the cross‐track direction, having opposite magnetizations. The domain boundary moved to right or left according to writing currents, and vanished by larger currents than 15 mA. Hemispherical domain structures with a diameter of around 0.6 µm, consisting of two opposite magnetizations in the direction of the applied magnetic field, were observed in several portions of the bottom pole. The domain structures also vanished with increasing field strength. Copyright © 2010 John Wiley & Sons, Ltd.

Liquid–liquid fluorescent waveguides using microfluidic-drifting-induced hydrodynamic focusing

We demonstrate fluorescent liquid-core/liquid-cladding (L 2) waveguides focused in three-dimensional (3-D) space based on a 3-D hydrodynamic focusing technique. In the proposed system, the core and vertical cladding streams are passed through a curved 90° corner in a microfluidic channel, leading to the formation of a pair of counter rotating vortices known as the Dean vortex. As a result, the core fluid is completely confined within the cladding fluid and does not touch the top and bottom poly(dimethylsiloxane) (PDMS) surfaces of the microfluidic channel. Because the core stream was not in contact with the PDMS channel, whose refractive index contrast and optical smoothness with the core fluid are lower than that between the core and the cladding fluids, the 3-D focused L 2 waveguide exhibited a higher captured fraction (η) and lower propagation loss when compared to conventional two-dimensional (2-D) focused L 2 waveguides. Because the proposed 3-D focused L 2 waveguides can be generated in planar PDMS microfluidic devices, such optofluidic waveguides can be integrated with precise alignment together with other in-plane microfluidic and optical components to achieve micro-total analysis systems (μ-TAS).

Electrophoresis Poly(Dimethylsiloxane)/Glass Chips with Integrated Active Cooling for Quantification of Amino Acids

The objective of this work was to develop and characterize a poly(dimethylsiloxane) device with an integrated active cooling function able to carry out capillary electrophoresis separations. Polymer-based microdevices are indispensable to recent advances in biomedical analysis. In particular, they have been applied to many microfluidic platforms owing to their low cost, ease of fabrication, and versatility in preparing complex microstructures. However, when applied to capillary electrophoresis separations, polymer microfluidic structures present an inherent disadvantage compared to glass and Si structures; they have a lower thermal conductivity than glass and Si. Although miniaturized devices allow operation at high electric fields, they face separation efficiency limitations due to Joule heating. There is, therefore, a strong need of developing capillary electrophoresis microfluidic structures with active cooling in order to operate at a higher electric field and potentially increase separation efficiency in these microdevices. A poly(dimethylsiloxane)/glass hybrid microfluidic capillary electrophoresis system is presented, where Joule heating was minimized by using an integrated active cooling function. Two poly(dimethylsiloxane) slabs with embedded microfluidic structures were irreversibly sealed on both sides of a thin glass slide. The top poly(dimethylsiloxane) slab was used to carry out capillary electrophoresis separations, whereas the bottom poly(dimethylsiloxane) slab was employed to cool down the buffer solution used during the capillary electrophoresis separation. As demonstrated on current versus voltage plots and on capillary electrophoresis electropherograms, capillary electrophoresis separation was able to be operated at a higher electric field when using the cooling function. The cooling rate was adjustable by varying the flow rate and the initial temperature of the liquid flowing in the cooling microfluidic structure.

Self-assembly of perylenediimide based semiconductor on polymer substrate

The continuous bi-layer composites consisting of top, ordered crystalline layer of perylenediimide derivative (2,9-di(pent-3-yl)-anthra[,1,9-def:6,5,10-d′e′f′]diisoquinoline-1,3,8,10-tetrone) - PTCDI-C5(3) and bottom poly(3-hexylthiophene-2,5-diyl) (P3HT) support were obtained from one solution, with a use of so called “two-step reticulate doping” method. Optical, atomic force and scanning electron microscopy images show that the top crystalline layer is made of relatively large, anisotropic domains composed of long, parallel crystals. The crystalline character of the surface layer of PTCDI-C5(3) grown on the P3HT film was confirmed by wide angle X-ray scattering measurements. Furthermore, the grazing-incidence angle X-ray diffraction experiments revealed that the self-assembly of PTCDI-C5(3) molecules on P3HT is dominated by π− π interaction between the conjugated perylene cores, and the stacks are parallel to the long axis of the crystals and to the polymer surface. The surface conductivity, measured along the long axis of the crystals was estimated to be ca. 2.4 10 − 8 Ω − 1 square − 1 at 285 K. Temperature dependence of the conductivity in the range 140–285 K reveal semiconductor-like behaviour with activation energy ca. 150 meV.

Analysis of Electrostatic Adhesion and Detachment of a Nonuniformly Charged Particle on a Conducting Plane

This paper presents the analysis of electrostatic adhesion and detachment of a charged, dielectric particle resting on a conducting plane. We have studied the effects of particle dielectric constant and the nonuniform charge distribution on the force acting on the particle. Charge on the particle surface is assumed to be smoothly varied and (a) concentrated at the bottom pole or (b) concentrated at the top and bottom poles. The analysis utilizes the method of multipole images to obtain accurate values of the electric field, and determines the electrostatic force from the stress on particle surface. Compared with the force on a uniformly charged particle having the same total charge amount, the analytical results show that the force is significantly enhanced by both kinds of nonuniform charge distribution treated in this work, and is particularly strong when charge is highly concentrated at the bottom pole. It is found that electric field in a limited range must be applied in order to detach the particle from the conducting plane. The electric field necessary for detachment depends strongly on the dielectric constant and the distribution of charge on the particle. The detachment becomes difficult for a particle with charged distributed at the bottom pole, and may be hardly possible if the dielectric constant is too high.

Stimulus-response compatibilities during top-bottom discriminations.

Participants indicated whether a small dot was located near the top or bottom pole of a rotated object. Response times increased as a function of object orientation more for top trials than for bottom trials. The interaction between orientation and response was shown to be due to a relationship between response times and the dot's height on the screen. The orientation effect was influenced, positively and negatively, by a vertical arrangement of the response keys depending on whether the upper or lower key was used for the top response. Horizontal key placement produced an intermediate orientation effect, with asymmetries of about 180 degrees depending on which hand was used for top responses. This task appears to reflect spatial stimulus-response compatibilities more than object processing.