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CITING REFERENCES
US6939311
Micro infusion drug delivery device Sterling Medivations, Inc. Inventor(s): Douglas, Joel S. Application No. 09/672456, Filed 20000929, Issued 20031007 Granted 20031007 Abstract: An infusion pump for use with standard pre-filled medication container and a drug delivery device for percutaneously administering a drug. The delivery device having a plurality of projections and a drug reservoir. The projections extend from the reservoir and are adapted for penetrating the stratum comeun for percutaneously administering a drug from the reservoir to produce a local or systemic physiological or pharmacological effect. The plurality of projections is formed by micro machining. The pump is made by using a micro-actuator and includes a housing having a lid which opens and closes so that the medication container can be inserted and supported in a delivery mode position.
US6623457 B1 Method and apparatus for the transdermal administration of a substance Becton, Dickinson and Company Inventor(s): Rosenberg, Zeil B. Application No. 09/401452, Filed 19990922, Issued 20030923 Granted 20030923 Abstract: A transdermal delivery device includes a plurality of microneedles for injecting a substance such as a pharmaceutical agent into or below the stratum corneum of the skin. The device has housing formed from a top and bottom wall to define a chamber for containing a pharmaceutical agent. An inlet port is provided in the top wall of the housing for supplying the pharmaceutical agent to the chamber and directing the agent to the microneedles. The housing can have a Luer lock type fitting for coupling with a syringe having a Luer lock collar to inject the pharmaceutical agent into the housing. The housing can be divided into a plurality of chambers by an internal wall for supplying different agents simultaneously or sequentially to a patient. The microneedles have a length of about 5-250 microns and generally about 50-100 microns.
US6620332 B2 Method for making a mesh-and-plate surgical implant Tecomet, Inc. Inventor(s): Amrich, Mark P. Application No. 10/021616, Filed 20011212, Issued 20030916 Abstract: Method for making a mesh-and-plate surgical implant includes the steps of applying maskant to first and second faces of a metal sheet, selectively ablating the maskant on both faces, affixing a first tape to the first face to cover same and maskant thereon, but leaving an exposed portion for a screw hole, affixing a second tape to the second face to cover same and maskant thereon, etching the first face screw hole portion to form a crater, removing the first tape, etching the crater and other exposed portions of the first face, removing the second tape, etching opposite the crater and other exposed portions of the second face to provide openings in communication with the crater, and other second face openings extending to the first face, and removing remaining maskant to provide the implant configured to include a pliable mesh portion and a rigid plate portion, and having a screw hole therein.
US6611308 B2 Cone protrusion in multi-domain vertically aligned liquid crystal display Hannstar Display Corp. Inventor(s): Wu, Long-Hai; Tanaka, Sakae Application No. 09/845520, Filed 20010430, Issued 20030826 Abstract: A pixel unit included in a multi-domain vertically aligned liquid crystal display is provided. The pixel unit includes a first insulating substrate having a first side and a second side, a second insulating substrate having a third side and a fourth side, a plurality of liquid crystal molecules filled between the first side of the first insulating substrate and the fourth side of the second insulating substrate, an electric field generation device for providing an electric field to change alignment of the liquid crystal molecules, and a cone protrusion formed on the first side of the first insulating substrate for generating an advance inclination of the liquid crystal molecules around the cone protrusion.
US6607673 B2 Method for manufacturing a diamond cylinder array having dents therein The University of Tokyo Inventor(s): Fujishima, Akira; Masuda, Hideki Application No. 09/932833, Filed 20010817, Issued 20030819 Abstract: A cylinder array of diamond having a dent in its cylinder top face is manufactured by subjecting a cylinder array of diamond to a plasma etching.
US6607513 B1 Device for withdrawing or administering a substance and method of manufacturing a device Becton, Dickinson and Company Inventor(s): Down, James; Harvey, Noel G.; Martin, Frank E.; Pettis, Ronald J.; Lastovich, Alexander G. Application No. 09/590062, Filed 20000608, Issued 20030819 Granted 20030819 Abstract: A device includes a plurality of skin penetrating devices for delivering or withdrawing a substance through the skin of a patient. The device has a support formed with a top and bottom end and a plurality of channels extending axially through the support. A plurality of the skin penetrating members is positioned in the channels with a tip extending from the bottom end of the support. A coupling member is attached to the support for coupling with a fluid supply and directing the fluid to the skin penetrating members. The skin penetrating members have a length of about 100 microns to about 2000 microns and are about 30 to 50 gauge.
US6603987 B2 Hollow microneedle patch Bayer Corporation Inventor(s): Whitson, Robert C. Application No. 09/877519, Filed 20010611, Issued 20030805 Abstract: A test strip is provided for use in the determination of the concentration of an a chemical in blood. The test strip comprises a plurality of microneedles and a test area. Each microneedle is adapted to puncture skin and to draw blood. The test area is in fluid communication with the microneedles. The test area contains a reagent adapted to produce a reaction indicative of the concentration of the chemical in blood.
US6599322 B1 Method for producing undercut micro recesses in a surface, a surgical implant made thereby, and method for fixing an implant to bone Tecomet, Inc. Inventor(s): Amrich, Mark P.; Buturlia, Joseph; Lynch, Robert F.; Rolfe, Jonathan L. Application No. 09/976722, Filed 20011012, Issued 20030729 Granted 20030729 Abstract: A surgical implant having a datum surface for engaging tissue. Embodiments of the surgical implant include a recess in an original datum surface having a sharp undercut ovoid configuration and a multiplicity of recesses that are interconnected.
US6595947 B1 Topical delivery of vaccines Becton, Dickinson and Company Inventor(s): Mikszta, John A.; Brittingham, John M.; Alarcon, Jason; Pettis, Ronald J.; Dekker, III, John P. Application No. 09/576643, Filed 20000522, Issued 20030722 Granted 20030722 Abstract: A method for delivering a substance to the epidermal tissue of skin. The method involves simultaneously disrupting only the stratum corneum of the skin and delivering the substance to the epidermal tissue of the skin.
US6591133 B1 Apparatus and methods for fluid delivery using electroactive needles and implantable electrochemical delivery devices Microlin LLC Inventor(s): Joshi, Ashok V. Application No. 09/723230, Filed 20001127, Issued 20030708 Granted 20030708 Abstract: The invention includes apparatus and methods for electrotransport of a drug or other beneficial agent through a skin or mucosal membrane surface. In one embodiment, at least one of the cathode or anode electrode of an electrochemical cell is configured, at least in part, as an electroactive needle for insertion all or part way through the stratum corneum of a patient's skin. A reservoir containing a beneficial agent may be provided in fluid communication with one or more electroactive needles, in which case the electroactive needle(s) may be configured with a hollow bore interior for transport of the beneficial agent directly into a subject's tissues. In a related embodiment, an electroactive needle is configured for intravenous and/or intramuscular use. The invention also includes an electrotransport system comprising an electrochemically active porous substrate. In a further embodiment, the invention comprises an electrotransport system having one or more implantable active porous electrodes.
US6591124 B2 Portable interstitial fluid monitoring system The Procter & Gamble Company Inventor(s): Sherman, Faiz Feisal; Arias, Francisco; Gartstein, Vladimir; Owens, Grover David; Jevtitch, Milan Marcel; Huang, Chow Chi Application No. 09/853442, Filed 20010511, Issued 20030708 Abstract: A strip-like microneedle device is provided that includes an array of hollow microneedles, a diaphragm pump to extract interstitial fluid from skin, and a sensor that detects the concentration of the fluid. The microneedle device can be interfaced to an external sensor to produce a reading, or can be self-contained. One version uses an attachable/detachable microneedle array as a single-use, disposable unit. The device is portable, and is used by placing one finger on the microneedle array, and actuating the diaphragm pump with another finger, thereby obtaining the fluid sample. Solid coated or transparent microneedles could instead be used as an in-situ sensor, with either electrodes or an optical sensor.
US6558361 B1 Systems and methods for the transport of fluids through a biological barrier and production techniques for such systems Nanopass Ltd. Inventor(s): Yeshurun, Yehoshua Application No. 09/589369, Filed 20000608, Issued 20030506 Granted 20030506 Abstract: A device for the transport of fluids through a biological barrier includes a number of microneedles projecting from the front face of a substrate. A conduit is associated with each of the microneedles to provide a fluid flow path for transport of fluid through a hole in the biological barrier formed by the corresponding microneedle. Each of the microneedles is configured to provide a penetrating tip, and each conduit terminates at an opening which is proximal with respect to the microneedle tip. Also described are microneedle-based devices with integrated MEMS pumping configurations for withdrawal and/or delivery of fluids, and remote healthcare systems based on such devices.
US6540675 B2 Analyte monitor Rosedale Medical, Inc. Inventor(s): Aceti, John Gregory; Loewy, Zvi Gerald; Moroney, III, Richard Morgan; Gregory, Christopher Carter; Zanzucchi, Peter John Application No. 09/741755, Filed 20001220, Issued 20030401 Abstract: Provided is an analyte monitoring device having a housing, the device comprising: a plurality of needles, each having a tip, a retracted position, a position wherein the tip is extended from the housing a distance adapted to pierce skin; an electrically or spring powered needle pushing apparatus movable to separately engage each of the needles to move each from the retracted position to the extended position; an energy source located within the housing; a plurality of analysis sites comprising an analysis preparation, each adapted to receive liquid from the needles to wet the analysis preparation; one or more light sources adapted to direct light at the analysis sites; one or more light detectors adapted to receive light from the analysis sites; and a processor.
US6533949 B1 Microneedle structure and production method therefor Nanopass Ltd. Inventor(s): Yeshurun, Yehoshua; Hefetz, Meir; de Boer, Meint; Berenschot, J. W.; Gardeniers, J. G. E. Application No. 09/677175, Filed 20001002, Issued 20030318 Granted 20030318 Abstract: A method for processing a wafer to form a plurality of hollow microneedles projecting from a substrate includes forming, by use of a dry etching process, a number of groups of recessed features, each including at least one slot deployed to form an open shape having an included area and at least one hole located within the included area. The internal surfaces of the holes and the slots are then coated with a protective layer. An anisotropic wet etching process is then performed in such a manner as to remove material from outside the included areas while leaving a projecting feature within each of the included areas. The protective layer is then removed to reveal the microneedles.
US6501976 B1 Percutaneous biological fluid sampling and analyte measurement devices and methods Lifescan, Inc. Inventor(s): Sohrab, Borzu Application No. 09/879106, Filed 20010612, Issued 20021231 Granted 20021231 Abstract: Devices and methods for sampling a biological fluid and measuring a target constituent within the biological fluid are provided. Generally, the subject devices include a sampling device configured to pierce a skin surface to provide access to biological fluid and concentrically-spaced working and reference electrodes positioned within the elongated sampling device that define an electrochemical cell for measuring the concentration of analyte within the biological fluid. The subject devices and methods are particularly suited for use in the sampling and concentration measuring of glucose in interstitial fluids. Also provided are kits that include the subject devices for use in practicing the subject methods.
US6406638 B1 Method of forming vertical, hollow needles within a semiconductor substrate, and needles formed thereby The Regents of the University of California Inventor(s): Stoeber, Boris; Liepmann, Dorian Application No. 09/478913, Filed 20000106, Issued 20020618 Granted 20020618 Abstract: A method of forming a needle includes the step of anisotropically etching a channel into the back side of a semiconductor substrate. The front side of the semiconductor substrate is then isotropically etched to form a vertical axial surface surrounding the channel. The resultant needle has an elongated body formed of a semiconductor material. The elongated body includes an axial surface positioned between a first end and a second end. The axial surface defines a channel between the first end and the second end. In one embodiment, the first end has a sloping tip with a single circumferential termination point.
EP1287847 A1 Improved micro-needles and methods of manufacture and use thereof LIFESCAN, INC. Inventor(s): Olson, Lorin Application No. EP02254617 EP, Filed 20020701, A1 Published 20030305 Abstract: A micro-needle (80) is provided which is particularly useful for the minimally invasive sampling of a biological fluid and/or the minimally invasive delivery of a drug or other formulation across the skin. The micro-needle (80) has a structure having a base (70) at a proximal end and a vertex (60) at a distal end (58), and an open lumen (55) extending there through and through which fluid may be transferred. The structure defines a structural axis (65) that intersects the lumenal axis (56) defined by the open lumen (55). The point of intersection (90) between these axes is at a point below the vertex (60) of the micro- needle (80) to provide a sharp apex (60) at the distal end (58) of the micro-needle (80) and defines the general configuration of the distal end (58) of the micro-needle (80), which may be selected or customized depending on the intended use of the microneedle (80). The micro-needle (80) may be integral with a measurement device for measuring the concentration of a constituent within sampled biological fluid and/or with a fluid reservoir for containing a fluid to be delivered, and may also be used in conjunction with a remote control means. Methods of making and using the micro-needle (80) of the present invention as well as kits comprising one or more of the micro-needles (80) are also provided.
EP1266619 A1 Biological fluid constituent sampling and measurement devices and methods Lifescan, Inc. Inventor(s): Shartle, Robert; Leong, Koon-wah; Kiser, Ernest Application No. EP02254038 EP, Filed 20020611, A1 Published 20021218 Abstract: A device for accessing biological fluid, sampling biological fluid constituents and determining the concentration of at least one target constituent within the accessed biological fluid is provided. The device has at least one micro-piercing member used to penetrate the skin to a selected depth and to access biological fluid, a constituent sampling means and a constituent measuring means. The constituent sampling means comprises a constituent transfer medium, such as a hydrophilic gel material, by which sampled constituents are transferred from the micro- piercing member to the measuring means. The measuring means includes an electrochemical cell having at least one porous electrode through which at least one sampled constituent is caused to enter into the electrochemical cell. Methods of sampling constituents within the skin and measuring the sampled constituents, as well as kits for practicing the invention are provided.
EP1088642 A1 Method and apparatus for manufacturing a device Becton, Dickinson and Company Inventor(s): Powell, Kenneth G.; Monahan, Larry A.; Sage, Burton H., Jr. Application No. EP00118933 EP, Filed 20000901, A1 Published 20010404 Abstract: A device, preferably a micro-device (10), is molded from a plastic material by injection molding, compression molding or embossing. A microabrader (10) can be molded having microneedles (14) for abrading the stratum corneum of the skin to form an abraded site in the tissue for enhancing drug delivery. The micro-device (10) is molded using a mold assembly having a silicon molding surface (76). The silicon molding surface (76) can include a recess (78) corresponding to the desired shape and length of the microneedles (14). The silicon molding surface (76) enables micron and submicron size features to be molded from polymeric materials without the polymeric material adhering to the mold surface. Micro-devices having molded features having micron and submicron dimensions can be rapidly produced without the use of a release agent.
WO2003055384 A1 A MINIMALLY-INVASIVE SYSTEM AND METHOD FOR MONITORING ANALYTE LEVELS BECTON, DICKINSON AND COMPANY Inventor(s): DENUZZIO, John, D.; STROHBEN, William, E., Jr. Application No. US0240303 US, Filed 20021217, A1 Published 20030710 Abstract: A minimally-invasive analyte detecting device (100) and method for using the same. The system and method employ a device having an active electrode (104) optionally coated with a substance (126), and a counter- electrode (106) that is configured at least partially surround the active electrode (104). The configuration of the auxiliary electrode (106) and active electrode (104) improves the current flow through the device (100) and increases the sensitivity of the device. When the device is placed against the patient's skin, the active electrode (104) is adapted to enter through the stratum corneum of a patient to a depth less than a depth in the dermis at which nerve endings reside. An electric potential is applied to the active electrode (104) and the analyte level is determined based on the amount of current or charge flowing through the device (100).
WO2003047689 A1 APPARATUS AND METHODS FOR FLUID DELIVERY USING ELECTROACTIVE NEEDLES AND IMPLANTABLE ELECTROCHEMICAL DELIVERY DEVICES MICROLIN LLC Inventor(s): JOSHI, Ashok, V. Application No. US0145421 US, Filed 20011129, A1 Published 20030612 Abstract: The invention includes apparatus and methods for electrotransport of a drug or other beneficial agent through a skin or mucosal membrane surface. In one embodiment, at least one of the cathode or anode electrode (38, 50) of an electrochemical cell is configured as an electroactive needle (40) for insertion through the stratum corneum of a patient's skin. A reservoir (52) containing a beneficial agent may be provided in fluid communication with one or more electroactive needles (40), where the electroactive needle(s) (40) a hollow bore interior for transport of the beneficial agent directly into a subject's tissues. In a related embodiment, an electroactive needle (40) is configured for intravenous and/or intramuscular use. An electrotransport system (32) comprising an electrochemically active porous substrate is also disclosed. In a still further embodiment, an electrotransport system having one or more implantable active porous electrodes (338) is disclosed.
WO2002100244 A2 MICROFABRICATED SURGICAL DEVICE THE REGENT OF THE UNIVERSITY OF CALIFORNIA Inventor(s): SEWARD, Kirk, Patrick; PISANO, Albert, P.; STUPAR, Philip, Anthony Application No. US0218203 US, Filed 20020605, A2 Published 20021219 ,A3 Published 20030306 Abstract: This invention relates to microfabricated surgical devices (10, 50, 52, 54, 60, 70, 80) made of conformally coated polymer (28).
WO2002092882 A1 METHOD FOR MAKING A MESH-AND-PLATE SURGICAL IMPLANT TECOMET, INC. Inventor(s): AMRICH, Mark, P. Application No. US0213618 US, Filed 20020430, A1 Published 20021121 Abstract: A mesh-and-plate surgical is manufactured by a method including the steps of applying a mask (22, 23) to first (28) and second (29) faces of a metal sheet (21), selectively ablating the mask on both faces, affixing a first tape (41) to the first face to cover same and maska thereon, but leaving an exposed portion (24A) for a screw hole, affixing a second tape (42) to the second face to cover same and mask thereon, etching the first face screw hole portion to form a crater (24C), removing the first tape, etching the crater and other exposed portions (24B) of the first face, removing the second tape, etching opposite (24C) the crater and other exposed portions of the second face to provide openings in communication with the crater, and other second face openings extending to the first face, and removing remaining mask to provide the implant configured to include a pliable mesh portion (43) and a rigid plate portion (33), and having a screw hole (39) therein.
WO2002091922 A1 PORTABLE INTERSTITIAL FLUID MONITORING SYSTEM THE PROCTER & GAMBLE COMPANY Inventor(s): SHERMAN, Faiz, Feisal; ARIAS, Francisco; GARTSTEIN, Vladimir; OWENS, Grover, David; JEVTITCH, Milan, Marcel; HUANG, Chow-chi Application No. US0214624 US, Filed 20020509, A1 Published 20021121 Abstract: A strip-like microneedle device is provided that includes an array of hollow microneedles, a diaphragm pump to extract interstitial fluid from skin, and a sensor that detects the concentration of the fluid. The microneedle device can be interfaced to an external sensor to produce a reading, or can be self-contained. One version uses an attachable/detachable microneedle array as a single-use, disposable unit. The device is portable, and is used by placing one finger on the microneedle array, and actuating the diaphragm pump with another finger, thereby obtaining the fluid sample. Solid coated or transparent microneedles could instead be used as an in-situ sensor, with either electrodes or an optical sensor.
WO0245771 A2 MICRONEEDLE ADAPTER BIOVALVE TECHNOLOGIES, INC. Inventor(s): ACKLEY, Donald, E.; JACKSON, Thomas; DAVIS, Shawn Application No. US0146845 US, Filed 20011108, A2 Published 20020613 ,A3 Published 20020919 Abstract: The present invention relates to an adapter (10) for the transport of fluids with a microneedle device. The adapter can receive a syringe (20), for example, that is used to transport a fluid through the adapter for injection into a patient using the microneedle device. The adapter can include a seal (32) through which a syringe needle (24) is inserted to deliver fluid from the syringe into a fluid cavity (34) in the adapter.
WO0217985 A2 MICRONEEDLE STRUCTURE AND PRODUCTION METHOD THEREFOR NANOPASS LTD. Inventor(s): YESHURUN, Yehoshua; HEFETZ, Meir; DE BOER, Meint; BERENSCHOT, J., W.; GARDENIERS, J., G., E. Application No. IL0100806 IL, Filed 20010828, A2 Published 20020307 ,A3 Published 20030109 Abstract: A method for processing a wafer to form a plurality of hollow microneedles projecing from a substrate includes forming, by use of a dry etching process, a number of groups of recessed features, each including at least one slot deployed to form an open shape having an included area and at least one hole located within the included area. The internal surfaces of the holes and the slots are then coated with a protective layer. An anisotropic wet etching process is then performed in such a manner as to remove material from outside the included areas while leaving a projecting feature within each of the included areas. The protective layer is then removed to reveal the microneedles.
WO0149362 A1 METHOD OF FORMING VERTICAL, HOLLOW NEEDLES WITHIN A SEMICONDUCTOR SUBSTRATE THE REGENTS OF THE UNIVERSITY OF CALIFORNIA Inventor(s): LIEPMANN, Dorian; STOEBER, Boris Application No. US0100040 US, Filed 20010102, A1 Published 20010712 Abstract: A method of forming a needle includes the step of anisotropically etching a channel into the back side of a semiconductor substrate. The front side of the semiconductor substrate is then isotropically etched to form a vertical axial surface surrounding the channel. The resultant needle has an elongated body formed of a semiconductor material. The elongated body includes an axial surface positioned between a first end and a second end. The axial surface defines a channel between the first end and the second end. In one embodiment, the first end has a sloping tip with a single circumferential termination point.
Electrochemical self-assembly of ordered quantum dot and wire arrays. Bandyopadhyay, Supriyo. Virginia Commonwealth University, USA. Editor(s): Wang, Zhong Lin; Liu, Yi; Zhang, Ze. Handbook of Nanophase and Nanostructured Materials (2003), 3 121-149. Publisher: Kluwer Academic/Plenum Publishers, New York, N. Y CODEN: 69DPQB Conference written in English. AN 2003:136414
Synthesis of Well-Ordered Nanopores by Anodizing Aluminum Foils in Sulfuric Acid. Sulka, G. D.; Stroobants, S.; Moshchalkov, V.; Borghs, G.; Celis, J.-P. Faculty of Chemistry, Department of Physical Chemistry, Jagiellonian University, Krakow, Pol. Journal of the Electrochemical Society (2002), 149(7), D97-D103. CODEN: JESOAN ISSN: 0013-4651. Journal written in English. CAN 137:239024 AN 2002:453080 Abstract: Well-ordered nanostructures were produced on industrial aluminum foils by one-, two-, and three-step anodizing processes performed in sulfuric acid at cell potentials between 15 and 25 V. Almost perfect triangular lattices of nanopores were obtained by the two- and three-step anodizing processes. It was found that the third step in the anodizing process neither significantly improves the ordering of the pores nor enlarges the size of the well-ordered domains. The effective growth rate of the oxide layer was calcd. for various cell potentials and compared with literature data. The effect of the anodizing time on the ordering of pores and the size of the domains was established. The pore diams. and the interpore distances were evaluated for various cell potentials, too. Anodizing in sulfuric acid results in small pore sizes and interpore distances compared to the ones obtained by anodizing in phosphoric and oxalic acids.
Effect of polishing pretreatment on the fabrication of ordered nanopore arrays on aluminum foils by anodization. Wu, M. T.; Leu, I. C.; Hon, M. H. Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan. Journal of Vacuum Science & Technology, B: Microelectronics and Nanometer Structures (2002), 20(3), 776-782. CODEN: JVTBD9 ISSN: 0734-211X. Journal written in English. CAN 137:223357 AN 2002:433275 Abstract: It is reported that a pretreatment step is required for the fabrication of ordered nanopore arrays on Al by anodization. One step anodization was carried out on the Al foils with different surface features that resulted from different polishing conditions. The effect of surface morphologies on their anodization characteristics was detd. When the nonelectropolished Al substrate was anodized, only limited-sized ordered domains could be obtained. Nearly perfect hcp. ordered pore arrays with domain size of .apprx.2-4 mm could be obtained on the electropolished Al substrate even with different surface features due to different electropolishing conditions. In addn., the differences of c.d. for the electropolished and nonelectropolished substrates were affected by the distinct characteristics of the oxide. The increase of the oxidn. current in the later stage of anodization was caused mainly by the breakdown of the oxide on the nonelectropolished substrates on which highly ordered pore arrays cannot be obtained.
Corrosion-related interfacial defects formed by dissolution of aluminum in aqueous phosphoric acid. Wu, Huiquan; Hebert, Kurt R.; Gessmann, Thomas; Lynn, Kelvin G. Department of Chemical Engineering, Iowa State University, Ames, IA, USA. Journal of the Electrochemical Society (2002), 149(4), B108-B116. CODEN: JESOAN ISSN: 0013-4651. Journal written in English. CAN 137:69599 AN 2002:316812 Abstract: The mechanism was investigated by which pit initiation on aluminum foils during anodic etching is affected by the use of phosphoric acid as a pretreatment. Positron annihilation measurements, coupled with at. force microscope images of foils with chem. stripped oxide layers, show evidence that the pretreatment introduces nanometer-scale voids in the metal, at or near the metal-oxide film interface. The location and morphol. of voids compares favorably with those of pits, suggesting that voids act as pit initiation sites. The no. of void sites was estd. to be 107 cm-2, the same magnitude as the max. no. of pits formed by anodic etching. Capacitance measurements further indicate that the treatment decreases the surface oxide thickness to about 2 nm. Formation of large nos. of pits during etching is promoted by either reduced oxide thicknesses or more pos. etching potentials. It is suggested that the rate of initiation of pits at interfacial voids is detd. by the elec. field in the overlying surface oxide.
Nanoscale pore formation dynamics during aluminum anodization. Thamida, Sunil Kumar; Chang, Hsueh-Chia. Department of Chemical Engineering, University of Notre Dame, Notre Dame, IN, USA. Chaos (2002), 12(1), 240-251. CODEN: CHAOEH ISSN: 1054-1500. Journal written in English. CAN 137:12283 AN 2002:162676 Abstract: A theor. anal. of nanoscale pore formation during anodization reveals its fundamental instability mechanism to be a field focusing phenomenon when perturbations on the min. of the two oxide interfaces are in phase. Lateral leakage of the layer potential at high wave no. introduces a layer tension effect that balances the previous destabilizing effect to produce a long-wave instability and a selected pore sepn. that scales linearly with respect to voltage. At pH >1.77, pores do not form due to a very thick barrier layer. A weakly nonlinear theory based on long-wave expansion of double free surface problem yields two coupled interface evolution equations that can be reduced to one without altering the dispersion relation by assuming an equal and in-phase amplitude for the two interfaces. This interface evolution equation faithfully reproduces the initial pore ordering and their dynamics. A hodograph transformation technique is then used to det. the interior dimension of the well-developed pores in two dimensions. The ratio of pore diam. to pore sepn. is a factor independent of voltage but varies with the pH of the electrolyte. Both the predicted pH range where pores are formed and the predicted pore dimensions are favorably compared to exptl. data.
Nonlinear phenomena during electrochemical oxidation of hydrogen on platinum electrodes. Varela, Hamilton; Krischer, Katharina. Abteilung Physikalische Chemie, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany. Catalysis Today (2001), 70(4), 411-425. CODEN: CATTEA ISSN: 0920-5861. Journal written in English. CAN 136:190714 AN 2001:872301 Abstract: H2 oxidn. on Pt electrodes, a comparatively simple electrocatalytic reaction, was known for a long time to exhibit a variety of complex temporal oscillations, depending on the compn. of the supporting electrolyte. The authors report, on the one hand, recent observations of spatial instabilities in the bistable and oscillatory region in this system. The studies indicate that the spatio-temporal dynamic is by far richer than was assumed so far. However, aperiodic responses of the system in cyclic voltammetric expts. are described. This behavior is similar to the one obsd. in potentiodynamic measurements during the electrooxidn. of small org. mols. A possible common origin of all these complex, current-voltage responses is discussed.
A nanospintronic universal quantum gate. Bandyopadhyay, S. Department of Electrical Engineering, University of Nebraska, Lincoln, NE, USA. Physica E: Low-Dimensional Systems & Nanostructures (Amsterdam, Netherlands) (2001), 11(2&3), 126-130. CODEN: PELNFM ISSN: 1386-9477. Journal written in English. CAN 136:143013 AN 2001:757307 Abstract: A simple self-assembled structure has been designed to perform universal 2-qubit operations. This can act as the basic building block of a solid state nanoscale quantum information processor. The gate consists of two tri-layered quantum dots that are electrochem. synthesized within two adjacent pores in a self-assembled porous alumina film. The two outer layers are ferromagnetic metals or semiconductors while the middle layer is a semiconductor with long spin coherence time (e.g. silicon). A single electron is injected into the middle semiconductor layer and its spin encodes a qubit. A target qubit is rotated by first lifting the spin degeneracy of the corresponding electron's ground state by applying a transverse potential to induce a Rashba interaction, and then making the spin-splitting energy resonant with a globally applied AC magnetic field. The controlled dynamics of the universal 2-qubit rotation requires exploiting the exchange coupling with the nearest neighboring dot. This coupling makes the spin-splitting energy in the target dot dependent on the spin orientation in the control dot. The ferromagnetic layers act as "polarizers" and "analyzers" for spin injection and detection, thus obviating the need for initialization and also providing a means for reading a qubit.
Capacitance-voltage spectroscopy of self assembled ordered arrays of quantum dots. Kouklin, N.; Bandyopadhyay, S. Department of Electrical Engineering, University of Nebraska, Lincoln, NE, USA. IEEE International Symposium on Compound Semiconductors, Proceedings of the IEEE International Symposium on Compound Semiconductors, 27th, Monterey, CA, United States, Oct. 2-5, 2000 (2000), 303-307. Publisher: Institute of Electrical and Electronics Engineers, New York, N. Y CODEN: 69BUND Conference written in English. CAN 135:325750 AN 2001:671509 Abstract: Compd. semiconductor quantum dots, self-assembled into a two-dimensional regimented hcp. array, have been studied by capacitance-voltage spectroscopy. The dots were synthesized by electrodepositing a semiconductor in a nanoporous alumite template formed by the anodization of aluminum. The capacitance-voltage characteristic indicates that the dots have n-type carriers and the Fermi level is unpinned. The capacitance traces out the regions of accumulation, depletion and inversion showing that carrier modulation is possible with a gate potential. Thus, these structures are ideally suited for quantum-dot flash memories.
Magnetic and structural properties of electrochemically self-assembled Fe1-xCox nanowires. Menon, L.; Bandyopadhyay, S.; Liu, Y.; Zeng, H.; Sellmyer, D. J. Department of Electrical Engineering and Center for Materials Research and Analysis, University of Nebraska, Lincoln, NE, USA. Journal of Nanoscience and Nanotechnology (2001), 1(2), 149-152. CODEN: JNNOAR Journal written in English. CAN 135:281962 AN 2001:621679 Abstract: Fe1-xCox (0 £ x £ 1) nanowires were self-assembled by electrodeposition in porous alumina films. The crystal structure is bee at the Fe end of the compn. With increased addn. of Co, the crystal structure remains bcc. until .apprx.67% addn. of Co. At the Co end, the structure is a mixt. of hcp. and fcc. Magnetic studies show high coercivities for the Fe-Co alloys in the bcc. phase. For Fe0.67Co0.33 nanowires of diam. 9 nm, the coercivity is .apprx.2900 Oe, whereas for Fe0.33Co0.67 nanowires, it is .apprx.2850 Oe. Temp. and size dependence of magnetic properties show no indication of superparamagnetic effects down to wire diams. of 9 nm.
Interaction of passivated clusters in solution with micro-patterned surfaces: Guided flow versus defect pinning. Parker, A. J.; Childs, P. A.; Palmer, R. E.; Brust, M. Semiconductor Devices Group, School of Electronic and Electrical Engineering, The University of Birmingham, Edgbaston, UK. Nanotechnology (2001), 12(1), 6-10. CODEN: NNOTER ISSN: 0957-4484. Journal written in English. CAN 135:69152 AN 2001:320793 Abstract: Gold nanoclusters, chem. passivated with decanethiol and dissolved in toluene, were deposited from soln. onto selected regions of oxidized silicon (100) surfaces patterned either with photoresist or an etched step. When the perimeter of a droplet crosses the boundary between the resist and the silicon surface, the authors observe transport of cluster soln. along such discontinuities, outside of the droplet. Such guided flow can extend for over 600 mm across the surface, producing cluster chains as narrow as .apprx. 120 nm, once the toluene has evapd. The same expt. with an etched step produces no transport of clusters, but rather selective deposition and growth around the discontinuity. These different responses are attributed to the step/boundary material-principally its interaction with the toluene solvent during evapn.
AFM study of topographical changes on aluminum surfaces in sulfuric acid under low current anodic dissolution. Nabi, T. M.; Sambe, H.; Ramaker, D. E. Chemistry Department, The George Washington University, Washington, DC, USA. Journal of Electroanalytical Chemistry (2001), 501(1-2), 33-40. CODEN: JECHES ISSN: 0368-1874. Journal written in English. CAN 135:67723 AN 2001:254377 Abstract: A study of the anodic dissoln. of polycryst. aluminum utilizing in-situ at. force microscopy (AFM) is reported. Terraced pyramidal walls with a const. characteristic width of 300-400 nm running relatively parallel to each other appear within a few minutes of dissoln. Upon further dissoln., these pyramidal walls are reduced to square terraced pyramids or ziggurats of const. width. AFM contour and profile plots reveal the extremely square and flat surfaces of the square plateaus on top of the ziggurats, all of them having the same size. Under the dissoln. conditions utilized, nucleation occurs at dislocation sites with primarily layer-by-layer dissoln. A long-range interaction between approaching dissoln. fronts decreases the dissoln. rate leaving the terraced pyramidal walls. This interaction is interpreted to arise from band bending in the oxidic layer existing on the surface. These features suggest that a strong role in the dissoln. kinetics is played by the non-local potentials caused by the electronic charge and band bending on the oxide layer. The terracing of the walls is believed to result from a short-range or chem. dissoln. effect. Possible applications of these prepd. surfaces are also discussed.
Spontaneous formation of spatiotemporal patterns at the electrode| electrolyte interface. Krischer, K. Fritz-Haber-Institut, Max-Planck-Gesellschaft, Berlin, Germany. Journal of Electroanalytical Chemistry (2001), 501(1-2), 1-21. CODEN: JECHES ISSN: 0368-1874. Journal; General Review written in English. CAN 135:67663 AN 2001:254375 Abstract: A review with 81 refs. concerning spontaneous formation of spatiotemporal patterns at the electrode| electrolyte interface is presented. Practically every electrochem. reaction exhibits temporal instabilities, such as bistable reaction rates or spontaneous oscillations of current or potential, in some range of the external parameters. In the presence of transport processes, or more generally of a mechanism that mediates a spatial coupling among different sites, temporal instabilities are usually accompanied by spatial symmetry breaking. This article reviews the different ways in which reaction term and spatial coupling can interact in electrochem. systems, and it summarizes the kind of patterns that may arise under different exptl. conditions. Emphasis is placed on establishing a connection between electrochem. mechanisms and prototype models in nonlinear dynamics to facilitate a classification of the different phenomena. This presentation seeks to be helpful in exploring possibilities to utilize nonlinear behaviors in technol. applications; some perspectives are discussed at the end.
Fronts, waves, and stationary patterns in electrochemical systems. Krischer, Katharina; Mazouz, Nadia; Grauel, Peter. Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany. Angewandte Chemie, International Edition (2001), 40(5), 850-869. CODEN: ACIEF5 ISSN: 1433-7851. Journal; General Review written in English. CAN 134:373287 AN 2001:211374 Abstract: A review with 77 refs. Oscillatory behavior was obsd. for almost all electrochem. reactions in a certain, although someArial small, range of external parameters. Only in the past ten years has it been possible, however, to find a common explanation for the occurrence of these temporal self-organization phenomena of chem. completely different electrochem. reactions. The breakthrough was achieved because new methods and concepts, which had been developed in nonlinear dynamics to describe the spontaneous formation of order in various disciplines, could be applied. This development in turn was only possible because the underlying laws are universal at a certain abstr. level. Oscillations are only one possible manifestation of nonlinear behavior. Examples of other features that are often closely assocd. with temporal instabilities are spatial structures and waves. Initiated by the theor. progress and the development of new exptl. techniques, spatial pattern formation in electrochem. systems was targeted for studies in the past few years. Based on these studies, it can be predicted under which conditions temporal or spatial pattern formation can be expected. Also, the possibility of predicting the occurrence of instabilities indicates that it might be feasible to exploit nonlinear effects to increase, for example, the yield of electrocatalytic reactions. Here the authors discuss physicochem. mechanisms that lead to pattern formation in electrochem. systems. At the same time, the authors stress the generic principles that are responsible for self-structuring processes in many chem. and biol. systems.
Highly ordered uniform quantum dots induced by ion sputtering. Kurz, H.; Facsko, S.; Bobek, T.; Dekorsy, T. Institute of Semiconductor Electronics, RWTH Aachen, Aachen, Germany. Materials Research Society Symposium Proceedings (2000), 618(Morphological and Compositional Evolution of Heteroepitaxial Semiconductor Thin Films), 3-10. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 134:259700 AN 2001:183147 Abstract: Self-organized hexagonally ordered quantum dot patterns are produced on GaSb (100) and InSb (100) surfaces by low energy Ar+ ion sputtering at normal angle of incidence. The quantum dots are cryst., exhibiting narrow size distributions with diams. 17-80 nm depending on sputter conditions, densely packed with densities as high as 2 ´ 1011 cm-2. The origin of the quantum dot formation is attributed to the interplay of two surface processes during ion bombardment: ion induced surface roughening, provoked by the curvature dependent sputter yield and balanced by surface diffusive processes. The obsd. quantum dot patterns obtained at different sputter conditions show that the formation mechanism can be described by the Kuramoto-Sivashinsky equation. The dominant diffusive process emerges to be effective ion induced without any mass transport on the surface, inherent to the sputtering process.
Processes in Open Systems on Crystal Surfaces with Low Miller Indices. Voitenko, V. A. St. Petersburg State Technical University, St. Petersburg, Russia. Technical Physics (Translation of Zhurnal Tekhnicheskoi Fiziki) (2001), 46(2), 234-239. CODEN: TEPHEX ISSN: 1063-7842. Journal written in English. CAN 134:301160 AN 2001:84186 Abstract: Exposure characteristics that were obtained when growing various films on natural low Miller index surfaces of several crystals were collected and analyzed. An evolution theory that explains their special form was constructed. The type of dose characteristics obtained suggests that the surface underwent a reconstruction, i.e., a nonequil. phase transition that occurs on the surface. A quant. anal. of the expts. available has been performed. In particular, a quant. estn. was obtained of to what extent coverage with lead hinders the oxidn. of the surface of a nickel crystal. Upon intense light or electron irradn. of silicon, divacancies are the predominant centers of the formation of point and extended radiation defects, as well as of local regions of melting. For some two-dimensional systems (divacancies, sulfur atoms on the surfaces of passivated semiconductors, oxide films), delay Arial and evolution Arial for the self-organized structure formed were detd.
The use of phosphoric acid immersion to enhance the susceptibility of aluminum to anodic pitting corrosion. Wu, H.; Hebert, K. R.; Gessmann, T.; Lynn, K. G. Department of Chemical Engineering, Iowa State University, Ames, IA, USA. Proceedings - Electrochemical Society (2000), 2000-4(Oxide Films), 189-197. CODEN: PESODO ISSN: 0161-6374. Journal written in English. CAN 134:122672 AN 2001:80311 Abstract: The immersion of high-purity Al foils in hot H3PO4 as a pretreatment for anodic etching in 1 M HCl at 70° was investigated. Pit no. densities of at least 105 cm-2 were found after 100 ms potentiostatic etching of both as-received and electropolished foil, compared to the order of 103 cm-2 on as-received foil with no H3PO4 pretreatment. Capacitance measurements suggested that this enhancement of pitting is related to a decrease of the barrier oxide thickness to »2 nm. Also, positron annihilation measurements, along with at. force microscope images of foils with chem. stripped oxide layers, showed evidence that the pretreatment introduces 10-100 nm large metallic voids at the metal oxide film interface. The locations and morphol. of these voids are correlated with those of pits. Thus, the pretreatment may both introduce pitting sites and increase their activation probability by thinning the oxide layer.
Electrochemically self-assembled ordered nanostructure arrays: Quantum dots, dashes, and wires. Bandyopadhyay, S.; Miller, A. E. Department of Electrical Engineering, University of Nebraska, Lincoln, NE, USA. Editor(s): Nalwa, Hari Singh. Handbook of Advanced Electronic and Photonic Materials and Devices (2001), 6 1-27. Publisher: Academic Press, San Diego, Calif CODEN: 69ARNX Conference; General Review written in English. CAN 134:123982 AN 2000:856306 Abstract: A review with 110 refs. on electrochem. self-assembled ordered nanostructure such as quantum wells, quantum dots, quantum wires and arrays. The properties and characterization of these devices are given. (c) 2001 Academic Press.
Quantum dots. Physics and applications. Wang, Kang L.; Balandin, Alexander A. Device Research Laboratory, Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, CA, USA. Editor(s): Markel, Vadim A.; George, Thomas F. Optics of Nanostructured Materials (2001), 515-549. Publisher: John Wiley & Sons, Inc., New York, N. Y CODEN: 69AQPW Conference; General Review written in English. CAN 134:155564 AN 2000:824622 Abstract: A review with 98 refs. The basic phys. properties of quantum dots are presented. The state-of-the-art fabrication techniques, different types of self-assembly and nanostamping, are summarized. Current and possible applications are considered.
Early stages of pattern evolution in anodic porous oxide film on Al 6061. Gao, Husheng; Scheeline, Alexander; Pearlstein, Arne J. Department of Mechanical and Industrial Engineering and Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Proc. - Electrochem. Soc. (2000), 99-33(Fundamental Aspects of Electrochemical Deposition and Dissolution), 101-109. CODEN: PESODO ISSN: 0161-6374. Journal written in English. CAN 133:356607 AN 2000:728734 Abstract: The evolution of anodic porous oxide films on Al 6061 in phosphoric acid was studied using a coaxially rotating, axially translating electrochem. reactor. The mass transfer rate is controlled by a const.-vol. continuous-feed electrolyte reservoir and a rotating cylindrical counter electrode, which supports stable Taylor vortex flow in the electrolyte. The results show that oxide film forms uniformly on the surface of Al alloy and the film/soln. interface is planar at the beginning of the oxidn. process. When the film reaches a crit. thickness, the planar interface becomes unstable, and oxide film grows and dissolves nonuniformly across the metal/film and film/soln. interfaces. As the dissoln. becomes more localized, a cellular structure forms and gradually evolves to more nearly circular structures.
Size dependence of the magnetic properties of electrochemically self-assembled Fe quantum dots. Menon, L.; Zheng, M.; Zeng, H.; Bandyopadhyay, S.; Sellmyer, D. J. Department of Electrical Engineering and Center for Materials Research and Analysis, University of Nebraska, Lincoln, NE, USA. Journal of Electronic Materials (2000), 29(5), 510-514. CODEN: JECMA5 ISSN: 0361-5235. Journal written in English. CAN 133:216660 AN 2000:525045 Abstract: A quasi-periodic array of Fe quantum dots of cylindrical shape has been synthesized by electrodeposition of Fe in porous alumina. By controlling the fabrication parameters, we have controlled the length, diam., and spacing of the dots. The magnetic properties are shown to depend on these parameters. It has been found that at room temp., there exists a crit. diam. of the dots for which the coercivity is a max. The largest value of coercivity obtained at room temp. is 2640 Oe which rises to 2900 Oe on annealing. At a low temp. of 5K, an increase in coercivity is obsd. for most of the samples. The largest value is 3800 Oe which rises to a value of 4100 Oe in the corresponding annealed counterpart. At 5K, no max. is seen in the coercivity as a function of diam. Instead, the coercivity is found to decrease with increasing diam. This dependence of the coercivity on diam. is discussed in terms of localized reversal effects.
Chemically self-assembled nanoelectronic computing networks. Bandyopadhyay, S.; Roychowdhury, V. P.; Janes, D. B. Department of Electrical Engineering, University of Nebraska, Lincoln, NE, USA. International Journal of High Speed Electronics and Systems (1998), 9(1), 1-35. CODEN: IHSSEF ISSN: 0129-1564. Journal; General Review written in English. CAN 133:170582 AN 2000:435054 Abstract: A review with 72 refs. Recent advances in chem. self-assembly will soon make it possible to synthesize extremely powerful computing machinery from metallic clusters and org. mols. These self-organized networks can function as Boolean logic circuits, associative memory, image processors, and combinatorial optimizers. Computational or signal processing activity is elicited from simple charge interactions between clusters which are resistively/capacitively linked by conjugated mol. wires or ribbons. The resulting circuits are massively parallel, fault-tolerant, ultrafast, ultradense and dissipate very little power.
Self-assembled nanoelectronic quantum computer based on the Rashba effect in quantum dots. Bandyopadhyay, S. Department of Electrical Engineering, University of Nebraska, Lincoln, NE, USA. Physical Review B: Condensed Matter and Materials Physics (2000), 61(20), 13813-13820. CODEN: PRBMDO ISSN: 0163-1829. Journal written in English. CAN 133:97806 AN 2000:360568 Abstract: Quantum computers promise vastly enhanced computational power and an uncanny ability to solve classically intractable problems. However, few proposals exist for robust, solid-state implementation of such computers where the quantum gates are sufficiently miniaturized to have nanometer-scale dimensions. A new approach is presented whereby a complete computer with nanoscale gates might be self-assembled using chem. synthesis. It is demonstrated how to self-assemble the fundamental unit of this quantum computer-a two-qubit universal quantum gate-based on two exchange coupled multilayered quantum dots. It is shown how these gates can be wired using thiolated conjugated mols. as elec. connectors. Each quantum dot in this architecture consists of ferromagnet-semiconductor-ferromagnet layers. The ground state in the semiconductor layer is spin split because of the Rashba interaction and the spin-splitting energy can be varied by an external electrostatic potential applied to the dot. A spin polarized electron is injected into each dot from one of the ferromagnetic layers and trapped by Coulomb blockade. Its spin orientation encodes a qubit. Arbitrary qubit rotations are effected by bringing the spin-splitting energy in a target quantum dot in resonance with a global ac magnetic field by applying a potential pulse of appropriate amplitude and duration to the dot. The controlled dynamics of the universal two-qubit rotation operation can be realized by exploiting the exchange coupling with the nearest-neighboring dot. The qubit (spin orientation) is read via the current induced between the ferromagnetic layers under an applied potential. The ferromagnetic layers act as "polarizers" and "analyzers" for spin injection and detection. A complete prescription for initialization of the computer and data input/output operations is presented. This paradigm, to the best of our knowledge, draws together two great recent scientific advances: one in materials science (nanoscale self-assembly) and the other in information science (quantum computing).
Nanoscopic studies of stainless steel electropolishing. Vignal, V.; Roux, J. C.; Flandrois, S.; Fevrier, A. Centre de Recherche Paul Pascal, UPR CNRS 8641, Universite Bordeaux I, Pessac, Fr. Corros. Sci. (2000), 42(6), 1041-1053. CODEN: CRRSAA ISSN: 0010-938X. Journal written in English. CAN 132:340447 AN 2000:278389 Abstract: Nanoscopic AFM studies of electrobrightening of stainless steel show that, under well defined exptl. conditions, a regular network of hexagonal cells (100 nm wide) can be obsd. at the surface of this alloy as it was at the electropolished aluminum surface. Its origin is tentatively attributed to an electroconvection process occurring at the metal/electrolyte interface.
Long-scale ordered nano-patterns formed by electrochemical polishing and anodization of polycrystalline and single crystal aluminum. Konovalov, Valery V.; Metzger, Robert M.; Zangari, Giovanni. Center for Materials for Information Technology, University of Alabama, Tuscaloosa, AL, USA. Proc. - Electrochem. Soc. (2000), 99-34(Electrochemical Technology Applications in Electronics), 203-208. CODEN: PESODO ISSN: 0161-6374. Journal written in English. CAN 132:314948 AN 2000:241983 Abstract: Nano-scale self-ordering in anodic porous alumina films and on electropolished aluminum surfaces was studied. The Masuda process for pore ordering, consisting of a single cycle of long-time anodization plus stripping of the oxide layer, was extended to multi-cycle variant. A multi-cycle process increases the initial ordering rate, but as soon as the ordered domain area of 1-1.5 mm2 is achieved, the ordering rate slows down, and does not depend on initial ordering. Long-time anodization improves the ordering; after 100 h an ordering on 10´10 mm2 size is demonstrated by 2-dimensional Fourier anal. Electropolishing Al single crystals produce different topogs. on different cryst. faces. For Al (110) highly ordered periodic stripes (periodicity 40-65 nm, height 2-7 nm) covered the whole sample (area » 1 cm2). On Al (100) and Al (111) surfaces ordered topogs. with hexagonal symmetry were obtained (periodicity 62-70 nm, height 5-10 nm), but only over 1-2 mm2 domains.
An electron-donor, band-bending mechanism for understanding the effects of anodic dissolution and dilute metal alloying on the pi | ||