Recoil Analysis Research Articles

Quantitative Coronary Angiographic Analysis of Spasm and Elastic Recoil After High Speed Rotational Atherectomy

This study evaluates the short‐term changes in coronary artery segments treated with high speed rotational atherectomy (HSRA). Quantitative coronary angiographic (QCA) analysis indices, such as degree of expected ablation, elastic recoil, and segmental spasm, were examined in 133 patients and restudied 24 hours after HSRA. The study was also designed to compare the early results of three different HSRA strategies: stand‐alone (SA) HSRA; HSRA with adjunctive high (≥ 4 atm) pressure (HP BA) and low (≥ 2 atm) pressure balloon angioplasty (LP BA). Previous studies have suggested negligible elastic recoil after HSRA as well as demonstrated the possibility of further continuous improvement in vessel patency up to 24 hours postprocedure. From a total of 656 patients treated with HSRA, a cohort of 133 patients with successful HSRA of 167 lesions were restudied angiographically at 24 hours. Serial QCA evaluation of the treatment site was performed. Analysis of the relative gain in minimal luminal diameter (MLD) assessed at 24 hours postprocedure showed that the highest gain group (> 40%) had narrower initial lesions compared to moderate gain (1%–40%), or MLD loss groups (MLD 0.5 ± 0.4 mm vs 1.0 ± 0.3 and 1.5 ± 0.4, respectively, P < 0.01). The initial percent diameter stenosis was also higher in the high gain group (77.1 ± 16.0 vs 61.9 ± 11.8 and 53.0 ± 11.9, P < 0.01). Immediately postprocedure there was a significant increase in MLD and a decrease in percent diameter stenosis. There was no difference in residual lesion characteristics postprocedure. While progressive MLD decrease was observed in the loss group (MLD postprocedure 1.6 ± 0.5 and 1.2 ± 0.6 at 24 hours, P < 0.01), a continuous increase in MLD was noted in the high gain group (MLD postprocedure 1.7 ± 0.5 mm vs at 24 hours 2.0 ± 0.5 mm, P < 0.01). The high gain group was characterized by the most lesion debulking, the most pronounced segmental spasm, and the least elastic recoil. Adjunctive HP BA was associated with the largest size vessels (D ref. in SA HSRA group was 2.6 ± 0.8 mm vs 2.9 ± 0.6 mm in LP BA and 3.0 ± 0.7 mm in HP BA groups, P < 0.01), the lowest elastic recoil (SA HSRA 23.8%± 20.9% vs LP BA 15%± 16.8% and HP BA 5.7%± 14.4%, P < 0.05), and the highest incidence of vessel dissection (SA HSRA 8.1% vs LP BA 14.7% and HP BA 34.0%, P < 0.05). However, these larger vessels underwent the least amount of lesion debulking (SA HSRA 46.4%± 27.2% vs LP BA 38.6%± 24.0% and HP BA 30.5%± 19.5%, P SA HSRA vs. HP BA < 0.001). There are measurable degrees of elastic recoil and local spasm observed after HSRA. HSRA of the most severe lesions yields the highest procedural gain, the lowest elastic recoil and the highest index of lesion ablation. In addition, some late increase in the MLD due to the resolution of spasm is observed at 24 hours postprocedure. SA HSRA is associated with higher degrees of expected lesion ablation. This is comparable to the degree of improvement in MLD, where adjunctive percutaneous transluminal coronary angioplasty is utilized as assessed at 24 hours postprocedure. HSRA with adjunctive HP BA yields immediate results showing the least elastic recoil and spasm at the expense of the highest incidence of dissection and side branch loss.

Friction and wear properties of as-deposited and carbon ion-implanted diamond films

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 × 10 17 carbon ions per cm 2. Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen (< 1 percent relative humidity), and ultrahigh vacuum (10 −7 Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10 −7 to 10 −8 mm 3 N −1 m −1) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10 −4 mm 3 N −1 m −1) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (<0.1 μmthick) of amorphous, nondiamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine- and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10 −7 mm 3 N −1 m −1). Even in ultrahigh vacuum, the presence of the nondiamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10 −6 mm 3 N −1 m −1. Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum.

Advances in Stanford phonon-mediated elementary particle detectors

We have demonstrated a new phonon sensor design based on aluminum phonon collection pads connected to tungsten transition-edge sensors (TES). The device is patterned onto a silicon crystal and phonons produced by events in the Si are absorbed into the aluminum films where about half of the energy is converted into long-lived quasiparticle excitations. These diffuse until they encounter the lower gap W regions where they deposit their potential energy to the electron system in the W. With the Si crystal at ∼ 40 mK, the W is kept near the center of its resistive transition ( ∼ 90 mK) using voltage bias and Joule self-heating. Current changes induced by particle events are measured with a high-bandwidth SQUID amplifier readout. We have demonstrated an energy resolution of ∼ 360 eV FWHM and a position sensitivity of ∼ 0.2 mm for 55Fe X-rays. We have also completed a new analysis of the nuclear recoil versus electron recoil ballistic phonon production experiments which used our earlier generation Ti TES on Si crystals. The new results set an upper limit on the distinction between the two phonon spectra and provide a better understanding of the phonon sensor response.

Time-of-flight elastic recoil analysis of ion beam modified nitrocellulose thin films

The erosion properties of nitrocellulose (C 6H 7N 3O 11) thin films on Si have been studied under exposure to 270 keV H, He, C, and Ar ions. Time-of-flight elastic recoil spectrometry has been applied to determine the atomic composition of the films as a function of deposited charge. All exposed films exhibit an initial removal of N and O consistent with RONO 2 bond breaking, proceeding at a rate that appears to depend on the density of electronic excitation. A non-volatile, carbon-rich residue remains after prolonged exposure to H, He, and C ions, while the film is effectively removed under Ar irradiation. Experimental evidence supports the proposition that binary collisions are an important mechanism affecting desorption of the H and C components. The results are consistent with a suggestion that complete volatilization of the film is determined by the nuclear stopping power of the incident ion.

A Nuclear Microprobe Examination of Catalysts Used in Hydrotreating and Hydroconversion of Petroleum Fractions

Nuclear microprobe methods have been developed to measure light element and metallic poison distributions in used catalysts. The methods are based on the irradiation of sectioned catalyst pellets with microbeams of energetic (MeV) charged particles. Irradiation with deuterons allows the determination of carbon and nitrogen by nuclear reactions, and vanadium, nickel, and other elements with atomic number >12 by particle-induced X-ray emissions. Hydrogen can be determined by an elastic recoil analysis method based on irradiation with helium ions. The development of the methods for catalyst applications is described. All elements can be determined at concentrations of <0.1 wt% at spatial resolutions as high as 5 μm. The methods have been applied to examine hydrotreating and hydroconversion catalysts used to treat heavy petroleum fractions. The extent of intra- and interpellet variations in deposited elements has been found to be high, but statistically acceptable average distributions can be obtained by examining no less than five pellets per batch. The interrelationship between deposited elements has been examined. An observation is that the H/C atom ratio of coke falls in regions of pellets containing high concentrations of vanadium. Early work indicates that nitrogen compounds tend to form coke nearer the surface of pellets than hydrocarbons. Information has been obtained on pore filling.

Hydrogen Incorporation in Sputter-Deposited, In-Chamber Annealed Amorphous Silicon Thin Films. An Infrared and Elastic Recoil Analysis

physica status solidi (a)Volume 145, Issue 2 p. K37-K42 Short Note Hydrogen Incorporation in Sputter-Deposited, In-Chamber Annealed Amorphous Silicon Thin Films. An Infrared and Elastic Recoil Analysis R. Rüther, R. Rüther Department of Electrical and Electronic Engineering, The University of Western Australia. Nedlands Search for more papers by this authorJ. Livingstone, J. Livingstone Department of Electrical and Electronic Engineering, The University of Western Australia. Nedlands Search for more papers by this authorN. Dytlewski, N. Dytlewski Lucas Heights Research Laboratories, Australian Nuclear Science and Technology Organisation, Lucas Heights Search for more papers by this authorD. Cohen, D. Cohen Lucas Heights Research Laboratories, Australian Nuclear Science and Technology Organisation, Lucas Heights Search for more papers by this author R. Rüther, R. Rüther Department of Electrical and Electronic Engineering, The University of Western Australia. Nedlands Search for more papers by this authorJ. Livingstone, J. Livingstone Department of Electrical and Electronic Engineering, The University of Western Australia. Nedlands Search for more papers by this authorN. Dytlewski, N. Dytlewski Lucas Heights Research Laboratories, Australian Nuclear Science and Technology Organisation, Lucas Heights Search for more papers by this authorD. Cohen, D. Cohen Lucas Heights Research Laboratories, Australian Nuclear Science and Technology Organisation, Lucas Heights Search for more papers by this author First published: 16 October 1994 https://doi.org/10.1002/pssa.2211450256Citations: 5 Nedlands, WA 6009, Australia. Lucas Heights, NSW 2234, Australia. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume145, Issue216 October 1994Pages K37-K42 RelatedInformation

Hydrogen Incorporation in Sputter-Deposited, In-Chamber Annealed Amorphous Silicon Thin Films. An Infrared and Elastic Recoil Analysis

Hydrogen Incorporation in Sputter-Deposited, In-Chamber Annealed Amorphous Silicon Thin Films. An Infrared and Elastic Recoil Analysis

Systematics of exclusive B decays.

Within a perturbative QCD framework we present a systematic analysis of the high recoil, in particular two body mesonic, decay channels of the $B$ meson. For decays involving $D$ mesons, all experimentally observed rates are in reasonable accord with our calculations. Noticeable corrections to heavy quark symmetry are found, appearing most prominently when comparing $D$ and ${D}^{*}$ decay modes. Calculated branching ratios involving the CKM matrix element ${V}_{\mathrm{ub}}$ are all below experimental upper bounds, but not markedly so. Calculated decay rates into charmonium lie a bit on the low side. Where color-suppressed diagrams contribute, they are found to be also suppressed dynamically and explicit calculation shows that the color-suppressed diagrams are ignorable in $B\ensuremath{\rightarrow}D\ensuremath{\pi}$ decays.

Precise determination of H recoil cross sections for 1.5–3.0 MeV He ions

The differential recoil cross sections of H have been determined for 1.5–3.0 MeV He + incidence. In order to obtain precise data, we have performed simultaneous detection and spectrum simulation of recoiled H and backscattered He. In addition, a careful cross check has been made by secondary ion mass spectrometry (SIMS). The present results have revealed a pronounced contribution from a nuclear short-range interaction. The He + energy and recoil angle dependence of the H recoil cross sections are well reproduced by adding the nuclear term, which is simply derived from effective range theory. Our computer simulation program of elastic recoil combined with Rutherford backscattering spectra makes it possible to determine the depth distributions of H together with other elements absolutely, without any ambiguities. The present elastic recoil analysis is employed to determine the H composition of amorphous Si(H) films deposited on Si wafers. An excellent agreement, better than 5%, is obtained between the elastic recoil and SIMS analyses.

Medium energy elastic recoil analysis of surface hydrogen

We describe a technique for the detection of light mass constituents at or near the surface of a material using two microchannel detectors to time the individual recoils. Sensitivity to hydrogen is demonstrated by probing samples of Kapton, hydrated titanium, and wafer grade silicon with 270 keV helium, neon, and argon ions. Because the detector is sensitive to particle velocity rather than energy, recoil atoms and scattered ions are easily distinguished. Processes which affect the system's sensitivity to hydrogen are identified and a value for the hydrogen detection efficiency is established. The method may realize a number of advantages over conventional elastic recoil detection, including the elimination of the absorber foil, heightened sensitivity, and improved depth resolution.

Quantitative analysis of elastic recoil after balloon angioplasty and after intracoronary implantation of balloon-expandable Palmaz-Schatz stents

Objectives. The purpose of this study was to measure elastic recoil from sequential angiograms after balloon angioplasty and after implantation of a balloon-expandable Palmaz-Schatz stent in the same patient, and to compare the results with the late angiographic outcome.Background. The immediate result of coronary balloon angioplasty is influenced by plastic deformation, primarily of the atherosclerotic plaque, and by elastic recoil, primarily of the less or nondiseased vessel circumference,Methods. The extent of elastic recoil was measured quantitatively as the difference between maximal balloon size and the resulting vessel diameter or cross-sectional area.Results. Analysis was performed in 60 patients who received a single stent for late restenosis after initially successful coronary balloon angioplasty. Minimal lumen diameter (minimal crosssectional area) was 0.98 ± 0.43 mm (0.97 ± 0.67 mm2) before balloon angioplasty, 2.06 ± 0.36 mm (3.68 ± 1.17 mm2) after angioplasty (both p < 0.001 vs. values before angioplasty) and 2.98 ± 0.26 mm (7.12 ± 1.28 mm2) after siteming (both p < 0.001 vs. postangioplasty results). No significant changes in vessel reference diameters or areas were measured. Mean balloon/artery ratios were similar in both procedures, ranging from 0.93 to 0.96. The calculated mean elastic recoil was 0.98 ± 0.50 mm in diameter (31%) and 3.67 ± 2.05 mm2in area (48%) after balloon angioplasty compared with 0.10 ± 0.07 mm (3.5%) and 0.38 ± 0.36 mm2(5.1%) after stenting. Increasing balloon sizes induced increased vessel stretch, which was followed by increased elastic recoil in the angioplasty group in contrast to the stalling group. Short, noncalcined and eccentric lesions tend to be associated with increased recoil after balloon angioplasty. Overdilation or under-dilation in one of the procedures, changes in postprocedural vasomotion or postprocedural thrombus formation was not responsible for this outcome. After 6 months mean minimal lumen diameter was 2.39 ± 0.58 mm, suggesting a mean hyperplasia of 0.59 ± 0.51 mm. Twelve patients (20%) had a follow-up diameter that was equal to or less than the mean postangioplasty result and eight patients (14%) had a diameter stenosis of >50%.Conclusion. The impiantation of a Palmaz-Schatz stent almost completely eliminates the decrease in vessel dimensions caused by elastic recoil and therefore diminishes the impact of hyperplasia and reduces the rate of restenosis.

Synthesis and characterization of fine grain diamond films

A fine grain diamond film has been developed by microwave plasma assisted chemical vapor deposition. Various analytical techniques, including Rutherford backscattering, proton recoil analysis, Raman spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. The grain size of the film was determined from bright and dark field electron micrographs, and found to be 200–1000 Å. The films exhibited good optical transmission between 2.5 and 10 μm, with a calculated absorption coefficient of 490 cm−1. The friction coefficients of this film were found to be 0.035 and 0.030 at dry nitrogen and humid air environments, respectively, and the films had low wear rates.

Characterization by Rutherford backscattering, elastic recoil and nuclear reaction analysis of near-surface modifications of glasses submitted to a DC potential

The near-surface modifications of glasses with different compositions were studied by the combination of three nuclear techniques for surface analysis: the resonant nuclear reaction 23Na(p, α)20Ne at Er = 591.6 keV, 2.2 MeV4He elastic recoil detection analysis and Rutherford backscattering spectrometry. Glass samples were submitted to a DC potential during different time intervals and temperatures. The influence of the electrodes on the surface modifications was studied. The modified layer thickness was related to the total charge which passed through the sample during the treatment. Continuous recording of the current flowing through the glass shows that, for a fixed voltage, there is a general decrease in the current with time. This behaviour was related to the surface composition modifications determined by the nuclear techniques.

Interdiffusion in polystyrene crosslinked by keV ion irradiation

Mass transport properties of polymers are deeply influenced by the presence of crosslinks between chains, induced by high-energy ion irradiation. Diffusion coefficients in polystyrene, measured after irradiation with 300-keV protons in the fluence range 1012–1014 ions/cm2, show strong variation up to two orders of magnitude. Diffusion process has been studied in deuterated/hydrogenated polystyrene bilayer by using the forward recoil analysis technique with 2.0-MeV He beam. The adopted experimental procedure allows us to detect diffusion coefficients in the range 5×10−13–10−15 cm2/s. Two molecular weights have been chosen for the hydrogenated polystyrene (7500 and 575 000 amu), in both experiments the molecular weight of deuterated polystyrene has been maintained constant (27 000 amu). Combining diffusion, molecular weight distribution, and solubility measurements performed in the same irradiation conditions, we have tested that diffusion process is slowed down when branching of chains or formation of a large unsoluble fraction occurs in the original polymer structure.

Combination balloon-ultrasound imaging catheter for percutaneous transluminal angioplasty. Validation of imaging, analysis of recoil, and identification of plaque fracture.

We investigated the hypothesis that an ultrasound transducer positioned within an angioplasty balloon could be used to perform quantitative assessment of arterial dimensions before and after percutaneous transluminal angioplasty (PTA) and to identify certain mechanical alterations consequent to PTA, including vascular wall recoil and the initiation of plaque fractures. A combination balloon-ultrasound imaging catheter (BUIC) that houses a 20-MHz ultrasound transducer within and halfway between the proximal and distal ends of an angioplasty balloon was used to perform PTA in 10 patients with peripheral vascular disease. Each PTA site was also evaluated before and after PTA by standard (nonballoon) intravascular ultrasound (IVUS) technique. In eight patients in whom satisfactory images were recorded with the BUIC before PTA, luminal cross-sectional area (XSA) of stenotic sites (0.10 +/- 0.01 cm2) did not differ significantly from measurements of XSA by IVUS (0.09 +/- 0.01 cm2, p = NS). Likewise, minimum luminal diameter (Dmin) measured by BUIC (0.34 +/- 0.02 cm) was similar to that measured by IVUS (0.33 +/- 0.01 cm, p = NS). In nine patients in whom satisfactory images were recorded with the BUIC after PTA, XSA measured by BUIC (0.29 +/- 0.03 cm2) did not differ significantly from XSA measured by IVUS (0.30 +/- 0.03 cm2, p = NS). Dmin measured by BUIC after PTA (0.57 +/- 0.02 cm) was also similar to Dmin measured by IVUS (0.57 +/- 0.03 cm, p = NS). After PTA, XSA and Dmin measured immediately after deflation were significantly less than balloon XSA and diameter at full inflation, indicating significant elastic recoil of the dilated site. For the nine patients in whom post-PTA images were satisfactory for quantitative analysis, including four patients in whom recoil was 39%, 46%, 50%, and 61%, percent recoil measured 28.6 +/- 7.2%. Finally, plaque fractures were identified on-line in six of 10 patients (60%); in each case, initiation of plaque fracture was observed at inflation pressures of 2 atm or less. The results of this preliminary human investigation indicate that an ultrasound transducer positioned within an angioplasty balloon can be used to perform quantitative and qualitative analyses of lumen-plaque-wall alterations immediately preceding, during, and immediately after PTA in patients with peripheral vascular disease.

Measurements of differential cross sections for electron-impact excitation to long-lived excited states of He, Ar, H 2, and N 2 by a molecular-beam recoil method

The velocity and angular distributions of the metastable species of He, Ar, H 2, and N 2, produced by electron impact on their supersonic molecular beams, were measured at several impact energies. The differential cross sections of the inelastic electron scattering due to formation of the metastable species were determined from the velocity and angular distributions by analysis of the beam recoil. The results agree well with those obtained by electron energy-loss spectroscopy. This method was also adopted to determine the differential cross sections for production of the high-Rydberg states of He and Ar atoms by electron impact.

Optical properties of ion-beam-deposited ion-modified diamondlike (a-C:H) carbon

Diamondlike carbon (DLC) is a hard, semitransparent material usually containing varying amounts of hydrogen. These materials have numerous potential applications, including use as coatings for infrared optics, and as such, the effects of damaging irradiation is of practical interest. In this paper we present results of variable angle spectroscopic ellipsometric (VASE) studies of ion-beam-deposited DLC films. These films have been further modified by directing 1-MeV gold ions, as well as 6.4-MeV fluorine ions, through the DLC and into the underlying silicon substrates, and the percentage of hydrogen in the film was measured versus fluence using proton recoil analysis. Optical analysis was performed assuming the Lorentz oscillator model. Three versions were used: one oscillator, two oscillator (with one fixed in energy), and two oscillator with all parameter variable. The latter model fits the VASE data extremely well, and the two oscillators can be interpreted as involving π to π* and σ to σ* band transitions. With ion modification the oscillators shift to lower photon energy, consistent with reduction in hydrogen concentration and possible increased graphitization.

Effect of Si 3N 4 encapsulation on the thermal processing of hydrogenated amorphous silicon

The properties of annealed hydrogenated amorphous silicon (a-Si:H) with and without Si 3N 4 encapsulation have been studied using Rutherford backscattering spectrometry, forward recoil analysis and scanning electron microscopy. Thermal processing of a-Si:H results in loss of hydrogen at temperatures above 375 °C with or without Si 3N 4 thin film encapsulation. With no encapsulation, the loss of hydrogen is preceded by the formation of bubbles which eventually break to form pinholes on the substrate. However, with Si 3N 4 encapsulation in the structure Si 3N 4/a-Si:H/Si no pinhole formation is observed.

Nuclear microprobe applications in materials science

Since its inception the nuclear microprobe has been used extensively in materials science studies. The ability of the technique to measure elements and isotopes by nuclear reaction analysis (NRA), particle induced X-ray emission (PIXE), Rutherford backscattering (RBS) and elastic recoil analysis (ERA) has proved particularly advantageous. There has been a notable increase in the exploitation of the technique to measure composition multidimensionally. Applications have involved the measurement of changes in the composition of materials during manufacture, fabrication and service, as these can strongly influence their properties. Examples have been drawn from plasma fusion research, the aero-industry, catalysis, power production, wear and the nuclear power industry.

Hydrogen isotope and light element profiling in solid tritium targets used for neutron production

Five targets consisting of titanium tritide layers on copper backings have been investigated using nuclear reaction analysis. As these targets are commonly used to produce monoenergetic neutrons via the T(p, n) 3 He and T(d, n) 4 He reactions, it is important to know of the presence of other elements which may produce neutrons at different energies. The thicknesses of the titanium tritide layers were measured by observing the T(p, n) 3 He threshold yield curve and also the energy spread of the neutrons using a 3 He-filled gridded ion chamber. Elastic recoil analysis with a particle identifying system was used to measure the hydrogen, deuterium, tritium and 3 He content, and elastic scattering was used to study the carbon and oxygen. Surprisingly high concentrations of both hydrogen and oxygen were found on all targets, including the three which had never been used. Also surprising was the 3 He content which was approximately the same for targets of all ages and conditions of use. As expected, the carbon content increased strongly with use, originating no doubt, from vacuum pump oil. Up to 3% deuterium atoms were observed in unused targets with much higher contents being recorded in used targets.