bluuebunny/crossref_metadata_2025 huggingface dataset:
Etching Rate Enhancement of Copper by Adding Sulfur Compounds in Chemical-Mechanical Polishing Slurries
Authors: Kanki Tsuyoshi , Shirasu Tetsuya , Kimura Takahiro , Nakamura Tomoji , Miyajima Motosyu
Published: September 2007

In the chemical mechanical polishing (CMP) process, we have discovered that the Cu etching rate can be enhanced without affecting the Cu slurry's pH by adding a small amount of the sulfur compounds MPS and Na2S2O3. Adding the sulfur compounds to the H2O2 slurry results in an increment in the oxidation reduction potential (ORP). The electrochemical model (mixed potential) showed that the ORP increment leads to enhancement of the Cu oxidizing reaction. Because XPS and Raman analysis of the Cu surface revealed that the Cu etching rate in CMP is limited by the Cu oxidizing reaction, we concluded that the Cu etching rate is enhanced by the addition of sulfur compounds to the Cu oxidizing reaction to increase the ORP increment.
XPS-study of Cu/epoxy Interfaces after different Wet Chemical Treatments
Authors: Siau Sam , De Roo Bert , Vervaet Alfons A.
Published: September 2007

In microelectronics build-up technology interfaces are realized between a polymer and a metal. The peel force is a measure for the quality of the adhesion. To improve adhesion between epoxy and electrochemically deposited copper, the polymer is generally pretreated with wet-chemical sweller and oxidizing treatments. It was shown that peel force is strongly dependent on the pretreatment conditions. This paper concerns different sweller and oxidizer treatment times for the epoxy. Copper is deposited by an electroless/electrogalvanic plating process. Before Cu-deposition and after peel force measurements, the obtained surface of the epoxy and the Cu-strips are studied with XPS. Atomic percentages of O, C, N, Cu, Pd and Sn are measured and the spectra are deconvoluted. Based on these results confirmations are presented for the proposed pore development in epoxy polymers due to wet chemical treatments (sweller and oxidizer). Between the XPS-results, peel force and AFM roughness measurements, correlations are presented.
Inhibition of Galvanostatic Nucleation of Zinc from a Zincate Solution by Cations of the Polymeric Tetraalkylammonium Salt
Authors: Kryshtop Yuriy , Yurchenko Natalya , Trofimenko Vitaliy
Published: September 2007

Galvanostatic formation of zinc nuclei on an isotropic pyrolitic carbon electrode from a pure zincate solution and a solution containing an additive of the polymeric tetraalkilammonium salt (TAS) was studied. The process was analyzed taking into account hydrophobic and hydrophilic parts (zones A and B, respectively) of an electrode surface on the charge transfer and crystallization stages. Due to a specific behavior of TAS adsorption on the surface of zones A and B, the nucleation process occurs in two steps. During the first period a few number of nuclei (N~105 cm-2) are formed on sites of zones B which are not occupied by TAS molecules. Under conditions of the constant j and inhibition of nuclei growth it causes an increase of supersaturation and secondary nucleation on occupied by TAS sites of the electrode and formation of a large number of nuclei (N~108 cm-2).
Determination of Diffusion Boundary Layers and Copper Thickness Uniformity in Plating Tools Designed for 3-D Interconnect and Packaging Applications
Authors: McCrabb Heather , Garich Holly , Gebhart Larry , Inman Maria , Taylor E. Jennings , Carpio Ron
Published: September 2007

Limiting currents under mass transport limiting conditions were determined experimentally for two distinct types of electrochemical plating cells using voltammetric and chronoamperometric methods. The average limiting currents were used to estimate the thickness of the diffusion boundary layer that results from the novel cell configurations and agitation schemes. Additionally, the deposit thickness uniformity across the surface of copper plated substrates was experimentally determined and reported as the coefficient of variation (CV). Results show that optimization of the cell configurations and solution agitation within provides a thin uniform diffusion boundary layer thickness and low CVs for the metal thickness distribution indicating a uniform current distribution is achieved across the surface of the substrate.
Mechanism of Selective Etching of SiGe Layers in SiGe/Si Systems
Authors: Kato Juri , Oka Hideaki , Kanemoto Kei , Hisamatsu Hirokazu , Matsuzawa Yusuke , Kitano Yoji , Hara Toshiki , Hoshina Masaki , Ohmi Shun-Ichiro
Published: September 2007

Selective lateral etching of the SiGe layer for various Si/SiGe/Si systems was studied. We showed the different etching rates for SiGe layers with the same thickness and Ge concentration, but with different structures of the Si/SiGe/Si stacked layer. We described a mechanism that could explain the experimental results of selective etching of SiGe layers in Si/SiGe/Si systems. According to the mechanism, we were able to summarize the following 3 key points in realizing high selectivity SiGe etching.  1) Should be the SiGe layer in a higher oxidation state (enough number of holes), 2) a wider area is necessary for Si substrate surface in contact with the solution, and 3) the current path should be maintained at the SiGe/Si interface.
Temperature Effect on LiFePO4 Cathode Performance
Authors: Guerfi Abdelbast , Ravet Nathalie , Charest Patrick , Dontigny Martin , Petitclerc Michel , Gauthier Michel , Zaghib K.
Published: September 2007

Two forms of LiFePO4 material were evaluated in lithium cells. One type of LiFePO4 (PI) that has a particle size ranging from 1-5 µm is compared to LiFePO4 (P-II) consisting of nano-particles. Coated electrodes on Al-carbon with thickness varying from 18 to 25 µm were used in this study. The addition of VGCF carbon fiber greatly improved the rate capability at low temperature. This suggests a good conductivity networking and wettability in the cathode. LiFePO4 (P-II) has improved the low- and high-rate discharge capacity. When VGCF fibers were combined with LiFePO4 (P-II) in the same composite cathode, the high rate capacity at 12C was increased by 51% compared to LiFePO4 (P-I) cathode with carbon black. At -10{degree sign}C and at 2C rate, 90 mAh/g was delivered from the cell. Cycling at 60{degree sign}C occurred with negligible capacity fade after 400 cycles. Furthermore, the cell was capable of good performance at high rate with 120 mAh/g at 10C, and it still has a good reserve at 25C with 73mAh/g.
TEM Studies of Carbon Coated LiFePO4 After Charge Discharge Cycling
Authors: Gabrisch Heike , Wilcox James , Doeff Marca M.
Published: September 2007

Carbon coating has proven to be a successful approach to improve the rate capability of LiFePO4 used in rechargeable Li-ion batteries. Investigations of the microstructure of carbon coated LiFePO4 after charge discharge cycling shows that the carbon surface layer remains intact over 100 cycles. We find micro cracks in the cycled material that extend parallel to low indexed lattice planes. Our observations differ from observations made by other authors. The differences between the orientations of crack surfaces in both studies can be reconciled considering the location of weak bonds in the unit cell and specimen geometry as well as elastic stress fields of dislocation.
Characterization of LiFePO4 at a Nanoscopic Scale in Relation to the Mode of Preparation
Authors: Mauger Alain , Ait-Salah Atmane , Massot Michel , Gendron Francois , Zaghib K. , Julien C.
Published: September 2007

We present a review of the structural properties of LiFePO4. Depending on the mode of preparation, different impurities can poison this material. These impurities are identified and a quantitative estimate of their concentrations is deduced from the combination of X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, Raman scattering (RS) spectroscopy and magnetic measurements. An optimized preparation provides samples with carbon coated particles free of any impurity phase, insuring structural stability and electrochemical performance that justify the use of this material as a cathode element a new generation of lithium secondary batteries.
An Electrochemical Cell with Capacitance-Enhanced Double Layer
Authors: Ngu Yves , Peckerar Martin , Kbheis Michael , Lowy Daniel , Goldsman Neil , Metze George , Tender Leonard
Published: September 2007

Initial studies on the fabrication of a new double-layer capacitor based on hydrated ruthenium oxide (RuO2.xH2O) are presented. The electrochemical capacitor cell is based on three designs approaches: active surface enhancement via corrugations, the use of an ultra-thin self assembled dielectric implemented with hydrated Ruthenium oxide and activated carbon powders in combination with sulfuric acid and the fusion of both processes. We address the key components of the electrochemical cell (i) packaging,; (ii) the methodology of incorporating sulfuric acid and the various powders, and (iii) the deposition technique for the powder. The powder composition was varied to establish its effect on the overall capacitance. Mixing RuO2.xH2O and AC yielded devices with the greatest capacitance value, whereas devices containing only one of the two components had capacitance values lower by a factor of 10-50. The devices have capacitance values as large as 50 mF/cm2 per plate pair.
Synthesis, Structure and Electrochemical Properties of LiFe2P3O10 Synthesized by Wet Chemistry
Authors: Ait-Salah Atmane , Ramana Chintalapalle V. , Gendron Francois , Morhange Jean Francois , Mauger Alain , Zaghib K. , Julien C.
Published: September 2007

We present the synthesis and characterization of a novel lithium iron polyphosphate LiFe2P3O10. Powders were prepared by wet-chemical technique from nitrate precursors followed by a series of thermal treatments. The crystal system is shown to be monoclinic (P21/m space group) and the refined cell parameters are a=4.596 Aå, b=8.566 Aå, c=9.051 Aå and β=97.46{degree sign}. LiFe2P3O10 has a weak ferromagnetic ordering below the Néel temperature TN=19 K. Electrochemical measurements were carried out in lithium cells with LiPF6-EC-DEC electrolyte at 25 {degree sign}C. The material delivered a capacity 70 mAh/g in the voltage range 2.7-3.9 V. The resulting cyclic voltammogram indicates a stable structure with a good reversibility with the redox peaks at 3.26 and 3.13 V vs. Li0/Li+.
Comparative Electrochemical Study of Low Temperature Fluorinated Graphites used as Cathode in Primary Lithium Batteries
Authors: Delabarre C. , Dubois Marc , Giraudet J. , Guerin Katia , Yazami Rachid , Hamwi Andre
Published: September 2007

In the present study we show the electrochemical performances of three series of fluorinated graphites CFx-MFn-T used as cathode materials in primary lithium batteries. Li/1M LiClO4 or LiBF4 PC /CFx were cells were discharged at different rates up to 1C. The electrochemical properties are correlated to physico- chemical characterizations. When the fluorine content increases, the capacity increases up to 900 Ah.kg-1. With increased covalency of the C-F bonding, the average discharge potential decreases from 3.15 to 2.31 V. The specific energy peaked at 2277 Wh.kg-1. Thermal storage was performed on cells and capacity losses upon ageing were found satisfactory.
Surface Modification of Carbonaceous Materials by Fluorinated Gases and Use as Anode in Lithium-Ion Battery
Authors: Groult Henri , Nakajima Tsuyoshi , Perrigaud Laurent , Warmont Fabienne , Ozhawa Yoshimi , Baddour-Hadjean Rita , Tressaud Alain , Julien C.
Published: September 2007

The electrochemical performances of raw and surface- fluorinated graphite powders used as anode in Li-ion battery have been studied. The fluorination obtained from F2 gas mainly concerns the surface of the particles for TF2≤300 {degree sign}C. For higher temperature, important modifications of the bulk structure were observed. When they are used as anode in Li-ion battery, fluorinated graphite powders exhibit better electrochemical performances than raw graphite notably due to an increase of the surface area and surface defects which allow the storage of a higher amount of lithium into the host lattice. These results have been confirmed by impedance measurements performed in delithiated state: a drastic decrease of both the charge transfer resistance and the resistance related to the SEI layer was observed for TF2 lower than 300 {degree sign}C.
Preparation of Porous Carbon with Bimodal Porous Structure and as a Electrode Material for Electric Double-Layer Capacitor
Authors: Woo Sang-Wook , Dokko Kaoru , Nakano Hiroyuki , Kanamura K.
Published: September 2007

3-D ordered macroporous carbon having wall composed of mesosized pores was prepared by colloidal crystal templating method. Colloidal crystals consisting of monodisperse polystyrene (PS) sphere (204 nm diameter) and silica particles (10~20 nm) were carbonized in Ar, and the silica was removed by etching in HF, and then porous carbon with bimodal porous structure was obtained. The specific surface area of the prepared carbon was 1003 m2 g-1, and the pore sizes of macropores and mesopores corresponded to the sizes of PS and silica particles, respectively. The electrochemical properties of the carbon were investigated as an electrode material for electric double layer capacitor in organic electrolytes. Specific double-layer capacitance of the prepared carbon in propylene carbonate containing 1 mol dm-3 (C2H5)4NBF4 was 94 F g-1 and showed relatively good rate capability.
High Performance 1,5-Diaminoanthraquinone/Multi-Wall Carbon Nanotube(DAAQ/MWCNT) Composite Materials by Different Synthesis Methods for Supercapacitor
Authors: Park Soo-Gil , Kim Hong-Il , Shin Jeong-Giun , Kim Han-Joo , Park Jong-Eun , Osaka T.
Published: September 2007

DAAQ(1,5-diaminoanthraquinone)/MWCNT composites were prepared by chemical polymerization of DAAQ onto MWCNT and their capacitance was evaluated by means of cyclic voltammetry and charge-discharge cycling in 1M H2SO4 electrolyte. The performances of such cells have been compared with pure MWCNT and DAAQ based electrodes. The SEM image shows that DAAQ was coated onto MWCNT during polymerization. The highest specific capacitance values of 210 F/g were observed. DAAQ/MWCNT composites also showed long cyclic stability in charge- discharge test.
The Magnetohydrodynamic Effect In Electrochemical Systems Including Batteries
Authors: O'Brien Robert N.
Published: September 2007

At vertical electrodes separated by a liquid electrolyte in any electrochemical process such as charging or discharging batteries, charging or discharging supercapacitors containing electrolytes, or in any process to convert by electrochemical means one substance into another, such as sodium chloride to sodium chlorate, or a racemate into one only chiral compound, the speed of the reaction can be increased by increasing transport to the electrodes if the electrodes or current collectors are magnetized. The result at a vertical electrode is enhancement of the natural convection and an increase in the maximum current density, or the cell will produce more product in a given time period; in a battery, a greater allowable current draw, and a lower loss of in-put energy on recharging.
Cellulose Based Activated Carbon for Electrochemical Double Layer Capacitors
Authors: Liu Ping , Soukiazian Souren , Verbrugge Mark
Published: September 2007

In an attempt to develop low-cost, high-performance activated carbon materials for electrochemical double layer capacitors, we explore the pyrolysis of a low cost precursor, cellulose sheets. Pyrolysis temperature is determined to be near 900oC by thermogravimetric analysis, and carbon dioxide etching is used to activate the carbon. Surface area and pore volume generally increase with etching time, and the electrochemical capacitance reaches a plateau of 60 to 65 F/g for etching times of more than 30 min. Degradation with cycling is observed and is attributed to the metal content in the raw material that may be enriched during the pyrolysis and etching processes.
Study on the Influence of Chloride Concentration on Copper Electrodeposition
Authors: Montes de Oca Yemha María G. , Mostany Jorge L. , Ramírez-Silva María Teresa , Romero-Romo Mario , Scharifker Benjamin R. , Palomar-Pardavé Manuel
Published: September 2007

Copper electrodeposition follows several paths depending on the system chemical variables to be controlled, such as pH and pCl that intervene directly in the thermodynamic study of the system. Thus in order to characterize the process it will also be required to gather kinetic information of the chosen system. Therefore, based on thermodynamic grounds, a system is construed to enable proper election of the electrochemical reaction paths to attain metal deposition, whether the process may start from one thermodynamic species or other, like Cu(II) or Cu(I).
Kinetics Mechanism of Copper UPD Nucleation and Growth on Mono and Polycrystaline Gold
Authors: Garfias-Garcia Elizabeth , Palomar-Pardavé Manuel , Romero-Romo Mario , Ramírez-Silva María Teresa , Batina Nikola
Published: September 2007

The copper electrodeposition process was studied onto different gold substrates, single crystal (111) and polycrystalline, using chronoamperometry. The potentiostatic current transients were analysed; it was found that, in both cases, different electrodeposition processes take place. In the underpotential region, the transients involve three types of processes, one of adsorption and two nucleation ones limited by the incorporation of ad-atoms, thus giving bidimensional growth for both electrodes.
Consistency of the Classical Theory of Nucleation with Nanometric Phenomena: A Comparison from Overpotential and Temperature Studies
Authors: Saavedra Karolly D. , Scharifker Benjamin R. , Mostany Jorge L.
Published: September 2007

A comparison between the activation energies for critical nuclei formation obtained from both the classical nucleation theory and Arrhenius kinetic analysis has been proposed. Results obtained indicate that such comparison is hampered by temperature-induced changes of the surface energies, modifying the contact angles and correspondingly the activation energies for nucleation. We have proposed a novel method to estimate the contact angle of metal nuclei, based upon the correlation of electrochemical and spectrophotometrical information. In the limiting case of instantaneous nucleation, we have shown that correlating the electrical charge with the obscuration due to electrodeposition allows determining the contact angle of metal nuclei.
Highly-Ordered Ultrathin Pd Films on Pt(111): Electrodeposition and Structural Characterization
Authors: Park Y. S. , Baricuatro J. , Hossain M. , Soriaga M. P.
Published: September 2007

The present manuscript describes the preparation, surface characterization, and interfacial electrochemistry of ultrathin Pd films, from submonolayer to multilayer coverages, electrodeposited on well-defined Pt(111) surfaces. Between the coverage regimes studied, the growth of the films followed the Stranski-Krastanov mechanism. The interfacial electrochemical properties associated with the film-to-bulk transition were characterized by voltammetric techniques in combination with low-energy electron diffraction and Auger electron spectroscopy. It was found that the Pd electrodeposit started to exhibit bulk-like properties at three monolayers. Voltammetric cycling, between the hydrogen evolution and the double-layer regions, was found to exert minimal influence on the smoothening of the electrodeposited films. However, cycling within the same potential region in the presence of bromide anions (at which Br- adsorption/Br desorption takes place) considerably smoothened the initially rough Pd films, comparable to hightemperature annealing. The influence of chemisorbed bromine on the anodic dissolution of Pd was also studied. The present studies indicated that bromine was desorbed along with the dissolution of the Pd step-atoms in a manner that may be described as electrochemical digital etching.
Theoretical Study on Ionic Surfactants that Participate in Electrochemical Adsorption Processes
Authors: Rosquete Giselle A. , Rosete-Perez Jaime , Ramírez-Silva María Teresa , Romero-Romo Mario , Palomar-Pardavé Manuel
Published: September 2007

Surfactants have been applied in diverse practical situations mostly related to adsorption phenomena. Also, micelles are quite important to electrocatalytic processes, namely in reactions with nonpolar substrates in aqueous environments. The Critical Micellar Concentration (CMC) and Surface Packing Parameter (G) are parameters that facilitate characterization of the micellization process. In this research work, we have calculated through Quantum Mechanics methods (DFT) a group of nine anionic surfactants. Thus, a model has been built of an hemimicelle fragment optimized by means of a semiempirical method AM1, which allowed us to obtain new geometric parameters with the aim to assess G in conditions where the surfactant molecule is not considered in isolation. A multiple lineal regression analysis was used employing the CMC as the dependent variable, to propose a Quantitative Structure- Property Relationship (QSPR)
The Interaction of Bromide Ions with Pd(100) Single-Crystal Electrode Surfaces: Studies by UHV-EC
Authors: Carrasquillo Arnaldo , Baricuatro J. , Hossain M. , Park Y. S. , Jeng J. J. , Soriaga M. P.
Published: September 2007

The influence of solution pH and electrode potential on the structure, composition, thermal stability and electrochemical reactivity of chemisorbed bromine on well-defined Pd(100) electrode surfaces was investigated by a combination of electrochemistry and ultrahigh vacuum surface spectroscopy. Br- ions chemisorbed oxidatively to form zerovalent Pd(100)- (2x2)-Br and Pd(100)-c(2x2)-Br adlattices. In acidic and neutral solutions, the surface coverages increased as the electrode potential was made more positive. The presence of Br- in solution induced anodic dissolution of Pd at pH < 7; however, at high overpotentials, the formation of a passivating film of PdBr2 precluded further surface dissolution. The surface coordination chemistry of Pd(100) exposed to Br- solutions at pH 10 resembled that of homogeneous halo-Pd complexes in which the only stable species at very alkaline solutions were metal hydroxides and/or metal-hydroxo complexes; that is, no Br chemisorption transpired on Pd(100) at pH 10.
Ca2+release dynamics in parotid and pancreatic exocrine acinar cells evoked by spatially limited flash photolysis
Authors: Won Jong Hak , Cottrell William J. , Foster Thomas H. , Yule David I.
Published: September 2007

Intracellular calcium concentration ([Ca2+]i) signals are central to the mechanisms underlying fluid and protein secretion in pancreatic and parotid acinar cells. Calcium release was studied in natively buffered cells following focal laser photolysis of caged molecules. Focal photolysis of caged-inositol 1,4,5 trisphosphate (InsP3) in the apical region resulted in Ca2+release from the apical trigger zone and, after a latent period, the initiation of an apical-to-basal Ca2+wave. The latency was longer and the wave speed significantly slower in pancreatic compared with parotid cells. Focal photolysis in basal regions evoked only limited Ca2+release at the photolysis site and never resulted in a propagating wave. Instead, an apical-to-basal wave was initiated following a latent period. Again, the latent period was significantly longer under all conditions in pancreas than parotid. Although slower in pancreas than parotid, once initiated, the apical-to-basal wave speed was constant in a particular cell type. Photo release of caged-Ca2+failed to evoke a propagating Ca2+wave in either cell type. However, the kinetics of the Ca2+signal evoked following photolysis of caged-InsP3were significantly dampened by ryanodine in parotid but not pancreas, indicating a more prominent functional role for ryanodine receptor (RyR) following InsP3receptor (InsP3R) activation. These data suggest that differing expression levels of InsP3R, RyR, and possibly cellular buffering capacity may contribute to the fast kinetics of Ca2+signals in parotid compared with pancreas. These properties may represent a specialization of the cell type to effectively stimulate Ca2+-dependent effectors important for the differing primary physiological role of each gland.
Acute infusion of nicotine impairs nNOS-dependent reactivity of cerebral arterioles via an increase in oxidative stress
Authors: Arrick Denise M. , Mayhan William G.
Published: September 2007

Our goals were to determine whether acute exposure to nicotine alters neuronal nitric oxide synthase (nNOS)-dependent reactivity of cerebral arterioles and to identify a potential role for oxidative stress in nicotine-induced impairment in nNOS-dependent responses of cerebral arterioles. We measured in vivo diameter of cerebral arterioles to nNOS-dependent ( N-methyl-d-aspartate and kainate) and -independent (nitroglycerin) agonists before and during acute treatment with nicotine. We found that nNOS-dependent, but not -independent, vasodilatation was impaired during treatment with nicotine. In addition, treatment of the cerebral microcirculation with tempol (1 h before infusion of nicotine) prevented nicotine-induced impairment in nNOS-dependent vasodilatation. Furthermore, the production of superoxide anion (lucigenin chemiluminescence) was increased in parietal cortex tissue of rats by treatment with nicotine, and this increase in superoxide anion production could be inhibited by tempol. Our findings suggest that acute exposure to nicotine impairs nNOS-dependent dilatation of cerebral arterioles by a mechanism that appears to be related to the formation of superoxide anion.
Rescue of cGMP Kinase I Knockout Mice by Smooth Muscle–Specific Expression of Either Isozyme
Authors: Weber Silke , Bernhard Dominik , Lukowski Robert , Weinmeister Pascal , Wörner René , Wegener Jörg W. , Valtcheva Nadejda , Feil Susanne , Schlossmann Jens , Hofmann Franz , Feil Robert
Published: September 2007

Smooth muscle expresses the Iα and the Iβ isoforms of cGMP-dependent protein kinase I (cGKI). Inactivation of the murine cGKI gene
prkg1
leads to multiple phenotypes and premature death at ≈6 weeks. We reconstituted mice with the cGKIα or -Iβ isozyme to test which isozyme was needed to support basic smooth muscle functions. Mice were generated by gene targeting. The cGKIα or the -Iβ coding sequences were placed under the control of the SM22α promoter to express either isoform selectively in smooth muscle cells (SM-Iα or SM-Iβ transgene). To generate smooth muscle–specific cGKIα or cGKIβ rescue mice, the SM-Iα or SM-Iβ transgenes were crossed on a cGKI
−/−
genetic background. The levels of cGKIα or -Iβ expression were comparable to endogenous cGKI expression in wild-type aortic and intestinal smooth muscles. In cGKIα or -Iβ rescue mice, expression of the isozymes was not detectable in non–smooth muscle tissues and cells. Median survival time of the Iα and Iβ rescue mice was 52 weeks. Both isozymes mediated the 8-bromo-cGMP–induced relaxation of precontracted jejunum and aorta muscle strips. Activation of both isozymes reduced hormone- or K
+
-induced [Ca
2+
]
i
levels. The cGKIα and cGKIβ rescue mice did not show a significant difference in intestinal passage time of BaSO
4
in comparison with wild-type animals. Telemetric blood pressure measurements in conscious freely moving animals did not show differences between rescues and control mice in basal blood pressure and its regulation by DETA-NO, sodium nitroprusside, carbachol, or Y-27632. These results show that cGKI in smooth muscle is essential and that either cGKI isozyme alone can rescue basic vascular and intestinal smooth muscle functions.
Electrical Induction of Ventricular Fibrillation for Resuscitation From Postcountershock Pulseless and Asystolic Cardiac Arrests
Authors: Leng Charles T. , Berger Ronald D. , Calkins Hugh , Lardo Albert C. , Paradis Norman A. , Halperin Henry R.
Published: September 2007

Background

—

There is increasing evidence that defibrillation from prolonged ventricular fibrillation (VF) before CPR decreases survival. It remains unclear, however, whether harmful effects are due primarily to initial countershock of ischemic myocardium or to resultant postdefibrillation rhythms (ie, pulseless electrical activity [PEA] or asystole).

Methods and Results

—

We induced 15 dogs into 12 minutes of VF and randomized them to 3 groups. Group 1 was defibrillated at 12 minutes and then administered advanced cardiac life support (ACLS); group 2 was allowed to remain in VF and was subsequently defibrillated after 4 minutes of ACLS; group 3 was defibrillated at 12 minutes, electrically refibrillated, and then defibrillated after 4 minutes of ACLS. All group 1 and 3 animals were defibrillated into PEA/asystole at 12 minutes. After 4 minutes of ACLS, group 2 and 3 animals were effectively defibrillated into sinus rhythm. The extension of VF in group 2 and 3 subjects paradoxically resulted in shorter mean resuscitation times (251±15 and 245±7 seconds, respectively, versus 459±66 seconds for group 1;
P
<0.05) and improved 1-hour survival (10 of 10 group 2 and 3 dogs versus 1 of 5 group 1 dogs; Fisher’s exact,
P
<0.005) compared with more conservatively managed group 1 subjects.

Conclusions

—

Precountershock CPR during VF appears more conducive to resuscitation than CPR during postcountershock PEA or asystole. The intentional induction of VF may prove useful in the management of PEA and asystolic arrests.
Random Research
Authors: Moyé Lemuel A.
Published: September 2007

Abstract—
Advances in computing have combined with the rapid dissemination of treatment discoveries for diseases of public health importance to create pressure for accelerated promulgation of promising research results to the medical community. The 2 recent examples of the US Carvedilol Heart Failure program and the Evaluation of Losartan In the Elderly (ELITE) study demonstrate the importance of the prospective nature of research design, as well as the consequences of its abandonment. This article explains in nonmathematical terms the rationale for the tenet “first say what you will do, then do what you said” in sample-based research.
Destruction of Contrast Microbubbles by Ultrasound
Authors: Ay Taniyel , Havaux Xavier , Van Camp Guy , Campanelli Barbara , Gisellu Giovanna , Pasquet Agnès , Denef Jean-François , Melin Jacques A. , Vanoverschelde Jean-Louis J.
Published: September 2007

Background

Recent experimental data indicate that ultrasound-induced destruction of ultrasound contrast microbubbles can cause immediate rupture of the microvessels in which these microbubbles are located.

Methods and Results

To examine the functional and morphological significance of these findings in the heart, isolated rabbit hearts were perfused retrogradely with buffer containing ultrasound contrast agents and were insonated at increasing levels of acoustic energy with a broadband transducer emitting at 1.8 MHz and receiving at 3.6 MHz and operated in the triggered mode (1 Hz). At the end of each experiment, the hearts were fixed in glutaraldehyde and examined with light microscopy. Neither exposure to ultrasound alone or to contrast alone affected left ventricular developed pressure. By contrast, simultaneous exposure to contrast and ultrasound resulted in a reversible, transient mechanical index (MI)-dependent decrease in left ventricular developed pressure (to 83±5% of baseline at an MI of 1.6) and a transient MI-dependent increase in coronary perfusion pressure (to 120±6% of baseline at an MI of 1.6). Myocardial lactate release also showed significant increases with increasing MIs. Macroscopically, areas of intramural hemorrhage were identified over the beam elevation in hearts exposed to both contrast and high-MI ultrasound. Light microscopy revealed the presence of capillary ruptures, erythrocyte extravasation, and endothelial cell damage. The mean percentage of capillaries ruptured at an MI of 1.6 was 3.6±1.4%.

Conclusions

Simultaneous exposure of isolated rabbit hearts to ultrasound and contrast agents results in an MI-dependent, transient depression of left ventricular contractile function, a rise in coronary perfusion pressure, an increase in lactate production, and limited capillary ruptures.
Improvement in Hypertension in Patients With Diabetes Mellitus After Kidney/Pancreas Transplantation
Authors: Elliott Michael D. , Kapoor Ajoy , Parker Michele A. , Kaufman Dixon B. , Bonow Robert O. , Gheorghiade Mihai
Published: September 2007

Background

Hypertension persists in many patients with diabetes mellitus after kidney transplantation. However, the impact of control of diabetes as well as kidney failure on hypertension by combined kidney and pancreas transplantation has not been studied.

Methods and Results

Between March 1993 and August 1998, 111 patients with type 1 diabetes mellitus underwent successful pancreas transplantation (108 kidney/pancreas transplantation) and another 28 patients with type 1 diabetes mellitus underwent isolated kidney transplantation. Blood pressure measurements and all antihypertensive medications were determined for both groups before transplantation and at 1, 3, 6, and 12 months and at the most recent outpatient evaluation after transplantation. At baseline, the mean blood pressure was 151/88 and 151/83 mm Hg for the kidney/pancreas and isolated kidney transplant patients, respectively. The mean blood pressure decreased to 134/77 mm Hg 1 month after kidney/pancreas transplantation (
P
<0.001) and decreased further to 126/70 mm Hg (
P
<0.001) at a mean follow-up of 18 months. This reduction in blood pressure after transplantation occurred despite a decrease in antihypertensive medications and the institution of immunosuppressive agents. At 1 month after kidney/pancreas transplantation, the average number of antihypertensive medications per patient was 0.9±1.0, compared with 2.5±1.1 before surgery (
P
<0.001). At 18 months after transplantation, 34% of patients were both normotensive (blood pressure ≤130/85 mm Hg) and receiving no antihypertensive medications. In contrast, there was no significant decrease in systolic blood pressure or antihypertensive medication use in the patients receiving an isolated kidney transplant.

Conclusions

Successful kidney/pancreas transplantation results in a marked improvement in hypertension treatment that is not observed in patients undergoing isolated kidney transplantation. These data underscore the importance of diabetes in the pathogenesis of hypertension in patients with diabetes and kidney failure.
Differential Effects of Angiotensin II Versus Endothelin-1 Inhibitions in Hypertrophic Left Ventricular Myocardium During Transition to Heart Failure
Authors: Iwanaga Yoshitaka , Kihara Yasuki , Inagaki Koichi , Onozawa Yoko , Yoneda Takeshi , Kataoka Kazuaki , Sasayama Shigetake
Published: September 2007

Background

In view of their mutual crosstalk, the roles of angiotensin II (Ang II) and endothelin-1 (ET-1) in the myocardium are assumed to be synergistic and supplemental.

Methods and Results

In the phase of compensated left ventricular (LV) hypertrophy of Dahl salt-sensitive rats, Ang II peptide and the ACE mRNA in the LV were increased by 1.6- and 3.8-fold, respectively. In contrast, ET-1 peptide and the preproET-1 mRNA remained unchanged. In subsequent congestive heart failure (CHF), Ang II and ACE mRNA did not show further increases. But ET-1 and the mRNA were increased de novo by 5.3- and 4.1-fold, respectively. In ascending aorta-banded rats, the local activations of Ang II and ET-1 also showed a differential time course between LV hypertrophy and CHF. Long-term treatments of Dahl salt-sensitive rats with temocapril (an ACE inhibitor) and with bosentan (a mixed ET receptor blocker) equally improved long-term survival. Temocapril reduced the LV/body weight ratio and ameliorated LV fractional shortening. Conversely, although bosentan equally improved fractional shortening, it did not reduce the increase in LV mass. Combined treatment with these 2 drugs further ameliorated the animal’s survival without additional decreases in systolic pressure.

Conclusions

The pathophysiological roles in the myocardium during the transition to CHF differ qualitatively between Ang II and ET-1. Thus, long-term therapy with a combination of ACE inhibition and ET antagonism may provide a new approach for heart failure in humans.
Nitroglycerin Induces Late Preconditioning Against Myocardial Infarction in Conscious Rabbits Despite Development of Nitrate Tolerance
Authors: Hill Michael , Takano Hitoshi , Tang Xian-Liang , Kodani Eitaro , Shirk Gregg , Bolli Roberto
Published: September 2007

Background
—

Recent studies suggest that the late phase of ischemic preconditioning (PC) can be mimicked by pretreatment with NO donors. The ability of clinically relevant NO donors to induce PC against infarction, however, has not been evaluated. Furthermore, it is unknown whether tolerance to the hemodynamic actions of nitrates also extends to their PC effects.

Methods and Results
—

Conscious rabbits underwent a 30-minute coronary occlusion and 3 days of reperfusion. A 60-minute intravenous (IV) infusion of nitroglycerin (NTG) ending 1 hour before occlusion reduced infarct size, indicating an early PC effect. When the time interval between NTG infusion and occlusion was extended to 24 or 72 hours, the infarct-sparing action of NTG became even more pronounced, indicating a robust late PC effect. Transdermal NTG patches elicited a late PC effect that was (1) equivalent to that induced by IV NTG, demonstrating the efficacy of transdermal NTG as an alternative form of NTG delivery for inducing late PC, and (2) similar in nitrate-tolerant and -nontolerant rabbits, demonstrating that tolerance does not extend to the PC effects of NTG.

Conclusions
—

In conscious rabbits, administration of NTG via either the IV or the transdermal route elicits a robust protective effect against infarction that lasts for 72 hours. The magnitude of NTG-induced cardioprotection is equivalent to that observed during the late phase of ischemic PC and is not affected by the development of tolerance. These findings reveal a new action of nitrates and support novel applications of these drugs for protecting the ischemic myocardium in patients.
Upregulation of the Cardiac Monocarboxylate Transporter MCT1 in a Rat Model of Congestive Heart Failure
Authors: Jóhannsson Erlingur , Lunde Per Kristian , Heddle Catherine , Sjaastad Ivar , Thomas Marion J. , Bergersen Linda , Halestrap Andrew P. , Blackstad Theodor W. , Ottersen Ole Petter , Sejersted Ole M.
Published: September 2007

Background

—

Cardiac metabolism becomes more dependent on carbohydrates in congestive heart failure (CHF), and lactate may be used as an important respiratory substrate. Monocarboxylate transporter 1 (MCT1) promotes cotransport of lactate and protons into and out of heart cells and conceivably flux of lactate between cells, because it is abundantly present in the intercalated disk.

Methods and Results

—

Six weeks after induction of myocardial infarction (MI) in Wistar rats, left ventricular end-diastolic pressures were >15 mm Hg, signifying CHF. MCT1 and connexin43 protein levels in CHF were 260% and 20%, respectively, of those in sham-operated animals (Sham), and the corresponding mRNA signals were 181% and not significantly changed, respectively. Confocal laserscan immunohistochemistry and quantitative immunogold cytochemistry showed that MCT1 density was much higher in CHF than in Sham both at the surface membrane and in the intercalated disk. In CHF, a novel intracellular pool of MCT1 appeared to be associated with cisternae, some close to the T tubules. In contrast, connexin43 particles, seen exclusively at gap junctions, were substantially fewer. Maximum lactate uptake was 107±15 mmol · L
−1
· min
−1
in CHF and 42±6 mmol · L
−1
· min
−1
in Sham cells (
P
<0.05). The
K
m
values were between 7 and 9 mmol/L (
P
=NS).

Conclusions

—

In cardiomyocytes from CHF rats, (1) the amount of functional MCT1 in the sarcolemma, including in the intercalated disk, is increased several-fold; (2) a new intracellular pool of MCT1 appears; (3) another disk protein, connexin43, is much reduced; and (4) increased reliance on lactate and other monocarboxylates (eg, pyruvate) could provide tight metabolic control of high-energy phosphates.
Impact of Smoking on Clinical and Angiographic Restenosis After Percutaneous Coronary Intervention
Authors: Cohen David J. , Doucet Michel , Cutlip Donald E. , Ho Kalon K.L. , Popma Jeffrey J. , Kuntz Richard E.
Published: September 2007

Background

Recent studies have suggested that smokers may require less frequent repeated revascularization after percutaneous coronary intervention (PCI) compared with nonsmokers. However, the mechanism of this phenomenon is unknown.

Methods and Results

We examined the association between smoking and restenosis using pooled data from 8671 patients treated with PCI in 9 multicenter clinical trials. Clinical restenosis was examined in the cohort of 5682 patients who were assigned to clinical follow-up only. Angiographic restenosis was evaluated in the subset of 2989 patients who were assigned to mandatory angiographic restudy. Among those patients assigned to clinical follow-up only, target lesion revascularization (TLR) occurred in 6.6% of smokers and 10.1% of nonsmokers (
P
<0.001). After adjustment for baseline clinical and angiographic differences, the rate of TLR remained significantly lower in smokers with an adjusted relative risk of 0.69 (95% CI, 0.54 to 0.88). Among the angiographic cohort, there were no differences in the rates of angiographic restenosis or follow-up diameter stenosis in either univariate or multivariate analyses. This dissociation between clinical and angiographic restenosis was explained in part by reduced sensitivity to restenosis on the part of smokers and by the greater reluctance of smokers to seek medical attention despite recurrent angina.

Conclusions

In patients undergoing contemporary PCI, cigarette smoking is associated with a lower rate of subsequent TLR without affecting angiographic restenosis. These findings have important implications for the follow-up of smokers after PCI and suggest that cross-study comparisons of rates of clinical restenosis must account for the potential confounding effect of smoking.
Biomechanical Hearts
Authors: Guldner Norbert W. , Klapproth Peter , Großherr Martin , Brügge Andreas , Sheikhzadeh Abdolhamid , Tölg Ralph , Rumpel Elisabeth , Noel Ralf , Sievers Hans-H.
Published: September 2007

Background

—

As shown previously in goats, clenbuterol increased the power of electrically conditioned skeletal muscle ventricles (SMVs) of clinically relevant size (150 mL), which were constructed around a mock system. They pumped against a pressure of 60 to 70 mm Hg immediately during surgery and up to several months after, finally at >1 L/min. SMVs without clenbuterol administration failed. Thus, we expected that clenbuterol-supported SMVs might become integrated into the circulation by a 1-step operation instead of the 2-step procedure required up to now.

Methods and Results

—

In adult Boer goats (n=5), latissimus dorsi muscle was wrapped around a polyurethane chamber of 150 mL that was connected to the descending aorta. This muscular flow-through pumping chamber containing a stabilizing inner layer (called a biomechanical heart [BMH]) was formed and immediately made to work against a systemic load with the support of clenbuterol (5×150 μg/wk). During surgery, the mean stroke volume of BMHs was 53.8±22.4 mL. One month after surgery, in peripheral arterial pressure, the mean diastolic (P
MD
) and minimal diastolic (P
min
) pressures of BMH-supported heart cycles differed significantly from unsupported ones (P
MD
=+2.9±1.1 mm Hg [
P
<0.04], P
min
=−2.4±0.9 mm Hg [
P
<0.04]). After BMH-supported heart contractions, the subsequent maximal rate of pressure generation, dP/dt
max
, increased by 20.5±8.1% (
P
<0.02). One BMH, catheterized 132 days after surgery, shifted a volume of 34.8 mL per beat and 1.4 L/min with a latissimus dorsi muscle of 330 g. Depending on duration of training, the percentage of myosin heavy chain type 1 ranged between 31% and 100%.

Conclusions

—

Under support of clenbuterol, BMHs of a clinically relevant size can be trained effectively in the systemic circulation after a 1-step operation and offer the prospect of a sufficient volume shift and probably unloading of the left ventricle.
Nicotine Does Not Influence Arterial Lipid Deposits in Rabbits Exposed to Second-Hand Smoke
Authors: Sun Yi-ping , Zhu Bo-qing , Browne Amanda E. , Sievers Richard E. , Bekker Janine M. , Chatterjee Kanu , Parmley William W. , Glantz Stanton A.
Published: September 2007

Background

Second-hand smoke (SHS) accelerates atherogenesis and impairs vascular function. The role of nicotine in this process has not been defined.

Methods and Results

To examine the potential effects of nicotine on atherogenesis and vascular function, 48 rabbits receiving a 0.5% cholesterol diet were randomized to control (cholesterol diet only), SHS from nicotine-standard research cigarettes (SHS-ST), and SHS from nicotine-free research cigarettes (SHS-NF). The SHS rabbits were exposed to 48 nicotine-standard (12 animals) or nicotine-free (12 animals) cigarettes/d, 5 d/wk for 10 weeks. Air carbon monoxide and particulates and plasma carboxyhemoglobin were significantly higher in the 2 SHS groups than the control group (
P
<0.001). The SHS-ST group had significant increases in plasma nicotine and cotinine compared with the other groups (
P
<0.001). There was no difference in serum lipids. Lipid lesions were increased in both SHS groups (54±5% [SEM] aorta and 66±4% pulmonary artery, 53±7% and 69±4%, and 39±4% and 43±3% in the SHS-ST, SHS-NF, and control groups, respectively;
P
=0.049 aorta and
P
<0.001 pulmonary artery).

Conclusions

SHS exposure increased arterial lipid lesions, but nicotine did not contribute significantly to this effect. This effect is presumably due to other combustion products in the smoke.
Neointimal Hyperplasia After Arterial Injury Is Increased in a Rat Model of Non–Insulin-Dependent Diabetes Mellitus
Authors: Park Si-Hoon , Marso Steven P. , Zhou Zhongmin , Foroudi Farhard , Topol Eric J. , Lincoff A. Michael
Published: September 2007

Background

The key biological determinants that promote restenosis in the setting of diabetes have not been elucidated. There is no accepted animal model to study restenosis in diabetes.

Methods and Results

We evaluated 2 models of diabetes mellitus: (1) streptozotocin (STZ)-treated Sprague-Dawley rats (type I diabetes) versus regular Sprague-Dawley rats and (2) obese Zucker rats (type II diabetes) versus lean Zucker rats. Neointimal hyperplasia was assessed after carotid balloon injury at 21 days by computerized morphometry. There was no difference in neointimal area in the STZ-treated rats compared with controls, irrespective of insulin administration or dose of STZ. Neointimal area was increased >2-fold in obese Zucker rats compared with lean Zucker rats (0.21±0.06 versus 0.08±0.03 mm
2
,
P
<0.01). The neointimal area was markedly increased in the obese Zucker rats 7 days after injury (0.058±0.024 versus 0.033±0.009 mm
2
,
P
<0.05) and persisted through 21 days. In both obese and lean Zucker rats, cell proliferation peaked in the media at 3 days (118.66±84.28 versus 27.50±12.75 bromodeoxyuridine-labeled cells per cross section). In the intima, cell proliferation markedly increased beginning at day 3 and persisted through day 14 in the obese and lean Zucker rats (202.27±98.86 versus 35.71±20.54 bromodeoxyuridine-labeled cells at 7 days).

Conclusions

The type II diabetic rat model, typifying insulin resistance, is associated with a propensity for neointima. The obese Zucker rat model may be an ideal diabetic model to further characterize the diabetic vascular response to injury.