bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolving Strategies for Treatment of Acute Aortic Dissection Type A
Authors: Kallenbach Klaus , Oelze Timm , Salcher Rolf , Hagl Christian , Karck Matthias , Leyh Rainer G. , Haverich Axel
Published: September 2004

Objective—

To assess the outcome of 3 different surgical approaches for treatment of acute aortic dissection type A (AADA).

Methods and Results—

Between October 1990 and October 2003, we operated on 295 patients (pts) for AADA. Follow-up was complete for 257 pts (87%). Supracommissural replacement (SCR) of the ascending aorta was applied to 145 pts, 64 pts received a composite replacement (comp), and 48 pts were treated with the aorta valve-sparing (AVS) reimplantation technique. Pts in SCR were older compared with AVS and comp (
P
=0.002), gender (overall 65% male,
P
=0.143) and presence of Marfan syndrome (overall 5%,
P
=0.109) were comparable. Cannulation of the aorta was performed more often in AVS (58%) than in comp (19%) or SCR (22%;
P
<0.001). Mean operation time, extracorporeal circulation time, and aortic cross-clamp time differ significantly between groups (
P
<0.001, respectively). Stay in the intensive care unit (
P
=0.12) and time of hospitalization (
P
=0.32) were comparable. Overall perioperative mortality was 24% and did not show significant differences between groups (AVS 10.4% versus comp 28% versus SCR 26%;
P
=0.053). Incidence of neurological complications was similar between groups (
P
=0.95). Mean time of follow-up was shorter for AVS (19±20 months) compared with comp (48±48 months) and SCR (46±45 months). Survival at 5 years was comparable with 89% for AVS, 85% for comp, and 80% for SCR (
P
=0.61). Two patients from AVS (4.1%) required reoperation for failure of the reconstructed valve. Pts in comp required less aortic reoperations than pts in SCR (comp 6.3% versus SCR 22%;
P
=0.005).

Conclusions—

In acute aortic dissection type A, the reimplantation technique leads to results comparable to established techniques. Complete removal of diseased tissue, low incidence of reoperation, and lack of anticoagulation may favor this approach in selected patients.
Differences in Gene Expression Profiles of Diabetic and Nondiabetic Patients Undergoing Cardiopulmonary Bypass and Cardioplegic Arrest
Authors: Voisine Pierre , Ruel Marc , Khan Tanveer A. , Bianchi Cesario , Xu Shu-Hua , Kohane Isaac , Libermann Towia A. , Otu Hasan , Saltiel Alan R. , Sellke Frank W.
Published: September 2004

Background—

Diabetes mellitus is an independent risk factor for early postoperative mortality and complications after coronary artery bypass grafting (CABG). We sought to compare the cardiac gene expression responses to cardiopulmonary bypass (CPB) and cardioplegic arrest (C) in patients with and without diabetes.

Methods and Results—

Twenty atrial myocardium samples were harvested from 5 type II insulin-dependent diabetic and 5 matched nondiabetic patients undergoing CABG, before and after CPB/C. Oligonucleotide microarray analyses of 12625 genes were performed on the 10 sample pairs using matched pre-CPB tissues as controls. Array results were validated with Northern blotting and immunoblotting. Compared with pre-CPB/C, post-CPB/C myocardial tissues revealed 851 upregulated and 480 downregulated genes with a threshold
P
≤0.025 (signal-to-noise ratio, 4.04) in the diabetic group, compared with 480 upregulated and 626 downregulated genes (signal-to-noise ratio, 3.04) in the nondiabetic group (
P
<0.001). There were 18 genes that were upregulated >4-fold in diabetic and nondiabetic patients (including inflammatory/transcription activators FOS, CYR 61, and IL-6, apoptotic gene NR4A1, stress gene DUSP1, and glucose-transporter gene SLC2A3). However, 28 genes showed such marked upregulation in the diabetic group exclusively (including inflammatory/transcription activators MYC, IL8, IL-1β, growth factor vascular endothelial growth factor, amphiregulin, and glucose metabolism-involved gene insulin receptor substrate 1), and 27 genes in the nondiabetic group only, including glycogen-binding subunit PPP1R3C.

Conclusions—

Gene expression profile after CPB/C is quantitatively and qualitatively different in patients with diabetes. These results have important implications for the design of tailored myocardial protection and operative strategies for diabetic patients undergoing CPB/C.
Effects of Paracommissural Septal-Lateral Annular Cinching on Acute Ischemic Mitral Regurgitation
Authors: Timek Tomasz A. , Lai David T. , Liang David , Tibayan Fredrick , Langer Frank , Rodriguez Filiberto , Daughters George T. , Ingels Neil B. , Miller D. Craig
Published: September 2004

Background—

Previous experimental studies demonstrated that central septal-lateral (SL) annular cinching (SLAC) abolishes acute ischemic mitral regurgitation (IMR), but whether localized cinching near the anterior (ACOM) or posterior (PCOM) commissure is equally effective is unknown.

Methods—

Six adult sheep underwent implantation of 9 radiopaque markers on the left ventricle, 8 around the mitral annulus (MA) and 1 on each papillary muscle (PM) tip. Transannular SL sutures were placed at the valve center (CENT) and near ACOM and PCOM and externalized. Acute IMR was induced by proximal circumflex coronary snare occlusion. Biplane videofluoroscopy and transesophageal echocardiography were performed before and continuously during 3 episodes of myocardial ischemia including 20 seconds of SLAC at each different location. End-systolic MA SL dimension at each suture location and distances between the anterior and posterior PM tips and mid-septal annulus (“saddle horn”) were calculated from the 3-dimensional (3D) marker coordinates.

Results—

SLAC interventions in all 3 locations reduced the degree of IMR, but cinching at the center, SLAC
CENT
, had a significantly greater effect on reducing the magnitude of IMR than SLAC
PCOM
or SLAC
ACOM
(mean grade of IMR reduction=1.0±0.5, 1.8±0.5, and 0.9±0.2 for SLAC
ACOM
, SLAC
CENT
, and SLAC
PCOM
, respectively;
P
=0.044). Although ACOM and PCOM cinching reduced SL
CENT
somewhat, only SLAC
CENT
simultaneously reduced both SL
ACOM
and SL
PCOM
and also repositioned both PM tips closer to the annular saddle horn.

Conclusions—

SLAC in all 3 positions reduced acute IMR, but central SLAC cinching was most effective, reduced all mitral annular SL dimensions, and relocated both PM tips closer to the mid-septal annulus. Central SLAC is most capable of correcting the annular and subvalvular perturbations accompanying acute left ventricular ischemia that lead to IMR.
Five-Year Angiographic Patency of Radial Artery Bypass Grafts
Authors: Cameron James , Trivedi Shailendra , Stafford Gregory , Bett J. H. Nicholas
Published: September 2004

Background—

Little information exists regarding mid-term and long-term patency of radial artery grafts.

Methods and Results—

We performed restudy coronary angiography at 5.2±0.4 years after surgery on 50 asymptomatic patients who had undergone coronary artery bypass graft surgery, using at least 1 radial artery graft, to determine both graft patency and presence of narrowing. We examined preoperative clinical or angiographic variables that might predict graft occlusion. Radial artery graft patency was 89%, with 91% of grafts free of narrowing. Preoperative New York Heart Association anginal class ≤2, target vessel proximal stenosis ≤70%, and small target vessel supply territory were predictive of graft occlusion.

Conclusion—

At 5 years after surgery, radial artery grafts have disease-free patency rates that are similar to other graft types.
Endovascular Treatment of Thoracic Aortic Disease
Authors: Bortone Alessandro S. , De Cillis Emanuela , D’Agostino Donato , Schinosa Luigi de Luca Tupputi
Published: September 2004

Background—

The aim of this retrospective study is to investigate efficacy and middle-term results of the stent graft treatment for diseases of descending thoracic aorta.

Methods and Results—

From March 1999 to October 2003, 132 patients (113 male and 19 female, mean age 62±14 years) were enrolled. They were divided into 4 groups: aneurysms (43, group A), post-traumatic lesions (24, group B), and complicated type B dissections (43, group C). Twenty-two further patients, with chronic type B dissection and not suitable for endovascular or surgical or hybrid techniques because of multiple entry tears without difference between the true and false lumen and poor clinical conditions, were obliged to receive medical management only (group D). All patients underwent computed tomography (CT) scan and angiography as preoperative assessment. An optimal deployment with exclusion of the aneurysm and/or closure of the entry tear in dissection was achieved in 96.4% (106/110) of the patients that were discharged in good conditions within 6 days. No spinal cord injuries were observed. The follow-up (average 20.82±10.01 months, range 1 to 55 months), performed with serial chest CT scans, was 100% complete. No stent graft-related complications were detected, although only in 1 case, an asymptomatic rupture of the Excluder connecting bar was found with a perforation of the fabric and an intra-aortic exposition of the bar itself. In 2 patients with chronic dissection an asymptomatic type II endoleak was detected. A total of 4 hospital deaths resulted in an overall operative mortality of 3.9%. Seven patients (6.3%) died during the follow-up 5 of them for other diseases (4.5%). However, a 40.9% mortality was observed within the obliged medical treatment group.

Conclusions—

Endovascular treatment of thoracic aortic diseases, even in the acute phase, may represent a valid option with a low mortality rate. Moreover, the efficacy is proved in the middle-term whereas the long-term follow-up is still pending.
Why Is Off-Pump Coronary Surgery Uncommon in Canada? Results of a Population-Based Survey of Canadian Heart Surgeons
Authors: Desai Nimesh D. , Pelletier Marc P. , Mallidi Hari R. , Christakis George T. , Cohen Gideon N. , Fremes Stephen E. , Goldman Bernard S.
Published: September 2004

Background—

Off-pump coronary artery bypass (OPCAB) is proposed to improve clinical outcomes and decrease resource use. However, off-pump surgery is not widely used in Canada. The purpose of this study was to determine the current use of OPCAB in Canada and determine why surgeons have not adopted this technique.

Methods and Results—

The study was a population-based survey of all adult Canadian cardiac surgeons in practice >1 year. Eligible division heads and surgeons were contacted by mail. Of 19 806 isolated coronary bypass surgeries performed by respondents in Canada last year, 3164 (16.0%) were performed off-pump. More than 50% of Canadian surgeons performed OPCAB in <5% of coronary cases, and only 17% of surgeons performed OPCAB in >25% of coronary cases. Only 4 responding centers performed OPCAB in >25% of cases. Respondents were divided into those who performed <5% of cases off-pump (nonadopters), 5% to 25% off-pump (intermediate users), or >25% off-pump (enthusiasts). Mean number of distal anastomoses in off-pump cases were 1.7±0.6, 1.6±0.6, and 3.3±0.5 for nonadopters, intermediate users, and enthusiasts, respectively (
P
=0.001). Eleven percent of nonadopters, 55% of intermediate users, and 81% of enthusiasts believed OPCAB improved clinical outcomes (
P
<0.0001). Only 23% of all respondents felt OPCAB use would increase in the next 5 years.

Conclusions—

Concerns regarding incomplete revascularization and lack of proven clinical benefit have limited OPCAB to being performed routinely by only a small number of surgeons in Canada.
Long-Term Patency of Internal Mammary Artery Bypass Grafts
Authors: Berger Alexandre , MacCarthy Philip A. , Siebert Uwe , Carlier Stéphane , Wijns William , Heyndrickx Guy , Bartunek Jozef , Vanermen Hugo , De Bruyne Bernard
Published: September 2004

Background—

Internal mammary artery conduits (IMA) have an excellent long-term patency rate. Nevertheless, graft closure does occur and significantly limits future revascularization options. We sought to investigate the relationship between the long-term patency of IMA with clinical and angiographic parameters. Particularly, the preoperative degree of stenosis of the relevant bypassed coronary vessel was assessed to analyze the importance of chronic competitive flow on the arterial graft closure rate.

Methods and Results—

Consecutive patients in whom occlusion of at least 1 IMA had been documented at angiography (OCC group) were compared with a group of patients with patent IMA grafts (PAT group). The degree of stenosis in the native coronary artery on which the IMA was placed was analyzed by off-line quantitative coronary angiography. Multivariate stepwise logistic regression was used to identify independent clinical and angiographic predictors of occlusion. The OCC group comprised 96 patients (67±10 years) with 103 native bypassed arteries analyzed. The PAT group comprised 127 patients (69±8 years) with 170 native bypassed arteries analyzed. Both groups were similar except for gender (42% versus 32% female;
P
=0.04), height (166±8 versus 169±8 cm;
P
=0.006), minimum lumen diameter (0.76±0.7 versus 0.51±0.5;
P
=0.001), and diameter stenosis of the native artery (73±25% versus 84±16%;
P
<0.0001) in OCC versus PAT, respectively. In the multivariate analysis, only percent diameter stenosis was an independent and statistically significant predictor for graft patency. Among IMA placed on coronary arteries with a diameter of stenosis <50% (n=28), the occlusion rate was very high (79%).

Conclusion—

The degree of stenosis in the native vessel is a major predictor of internal mammary artery bypass graft patency. The association between nonsignificant stenosis of the native artery and high occlusion rate of the arterial bypass conduit raises concerns about the use of IMA in the treatment of native vessels with only mild or moderate stenosis.
Using the Risk of Restenosis as a Guide to Triaging Patients Between Surgical and Percutaneous Coronary Revascularization
Authors: Kettelkamp Richard , House John , Garg Mukesh , Stuart R. Scott , Grantham Aaron , Spertus John
Published: September 2004

Background—

Coronary artery bypass graft (CABG) and percutaneous coronary revascularization (PCI) are strategies for treating coronary disease. Because the principal limitation of PCI is restenosis, CABG might be favored for those at high risk for restenosis. Using a clinical risk score for predicting restenosis, we examined whether patients with higher risks for restenosis were preferentially referred for CABG.

Methods and Results—

A procedural registry of 2320 revascularization patients from whom data on procedure type, demographics, comorbid conditions, health status, vessel anatomy, and outcomes were taken was analyzed. Patients were classified and scored into 3 categories of restenosis risk ranging from 11% to 44%, as defined by 8 preprocedural characteristics. The objective of this study was to describe referral patterns between PCI and CABG in each category of risk. 2060 patients underwent nonemergent revascularization. 1404 of the patients underwent PCI and 656 were treated with CABG. Among the patients at low and intermediate risk for restenosis, twice as many were referred to PCI. Among those at the highest risk, 3-times as many were referred to PCI, resulting in a significant trend for those with the higher risks of restenosis to be preferentially referred to PCI (
P
=0.015). Similar results were seen when the analysis was restricted to only those with multivessel disease.

Conclusions—

Patients at higher risk for restenosis were being preferentially treated with PCI as opposed to CABG. These results may have implications for reevaluating current patterns of triaging patients between PCI and CABG, and for the use of drug-eluting stents within PCI patients.
Pathophysiology of Vascular Calcification in Chronic Kidney Disease
Authors: Moe Sharon M. , Chen Neal X.
Published: September 2004

Patients with chronic kidney disease (CKD) on dialysis have 2- to 5-fold more coronary artery calcification than age-matched individuals with angiographically proven coronary artery disease. In addition to increased traditional risk factors, CKD patients also have a number of nontraditional cardiovascular risk factors that may play a prominent role in the pathogenesis of arterial calcification, including duration of dialysis and disorders of mineral metabolism. In histological specimens from the inferior epigastric artery of dialysis patients, we have found expression of the osteoblast differentiation factor core binding factor α-1 (Cbfa1) and several bone-associated proteins (osteopontin, bone sialoprotein, alkaline phosphatase, type I collagen) in both the intima and medial layers when calcification was present. In cultured vascular smooth muscle cells, the addition of pooled serum from dialysis patients (versus normal healthy controls) accelerated mineralization and increased expression of Cbfa1, osteopontin, and alkaline phosphatase to a similar magnitude as does β-glycerophosphate alone. However, a lack of inhibitors of calcification may also be important. Dialysis patients with low levels of serum fetuin-A, a circulating inhibitor of mineralization, have increased coronary artery calcification and fetuin-A can inhibit mineralization of vascular smooth muscle cells in vitro. These data support that elevated levels of phosphorus and/or other potential uremic toxins may play an important role by transforming vascular smooth muscle cells into osteoblast-like cells, which can produce a matrix of bone collagen and noncollagenous proteins. This nidus can then mineralize if the balance of pro-mineralizing factors outweighs inhibitory factors.
Asymptotic Homogenization and Numerical Implementation to Predict the Effective Mechanical Properties for Electromagnetic Composite Conductor
Authors: Fang Zhibin , Sun Wei , Tzeng Jerome T.
Published: September 2004

Conventional mechanics-based homogenization model and the finite element approaches have inherent limitations and errors when applying to calculate the effective properties of composites. These errors are either caused from the upper and lower bounds due to the difference of the prescribed boundary conditions, or from the effect of the size and the boundary condition of the representative element. Asymptotic theory-based homogenization does not have the inherent bounds and boundary errors but requires a complicated numerical implementation in order to apply the theory. This paper reports a development of an asymptotic theory-based homogenization approach with its numerical implementation and considers its application to predicting the effective mechanical properties of electric conductor consisting of conductor core and multi-layered composite insulations. The numerical implementation is developed based on using the finite element technique for the meshing generation and for the application of boundary conditions, with the developed computational algorithm for numerical calculation of effective homogenization properties. The developed computational program bridges the commercial CAD and finite element software, thus allows the design studies and parametric analyses of composite conductors with complex geometry and material composition.
Effect of Chemical Treatment on the Mechanical Properties of Starch-Based Blends Reinforced with Sisal Fibre
Authors: Vallo Claudia , Kenny Jose M. , Vazquez Analia , Cyras Viviana P.
Published: September 2004

Biocomposites were produced using polycaprolactone (PCL) and starch as the matrix, and washed and treated sisal fibres as reinforcement. The matrix consists of a biodegradable product commercially known as MaterBi-Z®, which is based on a PCL, starch and additive.

Alkaline and acetylation treatments were performed on the fibre in order to enhance the adhesion degree and the compatibility between the fibre and the matrix. The effect of chemical treatment on morphology, physical and chemical properties and tensile properties of fibres and composites were determined. Tensile properties of the biodegradable composite were improved by the presence of the fibre. However, the untreated fibres behaved as better reinforcement than the acetylated and alkalitreated fibres. This was attributed to an impairment of the mechanical properties of the acetylated fibres and incompatibility of the alkali-treated fibres. The results observed are supported by SEM analysis of fibres and the composite materials.
Optimal Design of a Multiperforated Composite Plate
Authors: Grediac M. , Alzina A. , Marquis D.
Published: September 2004

Multiperforated composite structures are used in some detectors for transition radiation tracking. These structures exhibit a shear coupling because of the inclined lines of holes in which sensors are fixed. This shear coupling may cause the buckling of the structure or may reduce the accuracy of the measurement provided by the sensors. The objective of this work is to propose a design procedure which eliminates this parasitic effect by designing a suitable stacking sequence. The procedure is carried out within the framework of the classical lamination theory assuming that the network of holes behaves like a virtual ply, the properties of which are determined with finite element calculations and a homogenization. However, the mechanical response of this virtual ply depends on the mechanical properties of the constitutive material too. The design procedure is therefore iterative, the properties of this virtual ply being updated at each step. The design procedure is described and some examples illustrate the relevance and the efficiency of the approach.
Characterization of Impact Properties and Damage Process of Glass/Epoxy Composite Laminates
Authors: Liu Dahsin
Published: September 2004

This paper investigates the responses of glass/epoxy composite laminates subjected to impact loading. It presents a new technique to characterize the impact properties and to correlate them with the damage process of the composite laminates. The technique, called the energy profiling technique, is based on instrumented impact tests and the least-squares method. The technique gives specific definitions of the penetration and perforation thresholds of the composite laminates. It also defines the range of the penetration process and quantifies the energy absorption efficiency of the composite laminates. The primary damage modes in the damage process of the composite laminates can also be correlated with the impact properties by using the energy profiling technique. The advantages of using this technique to analyze the experimental data obtained from impact tests are demonstrated by investigating the glass/epoxy composite laminates with various impactor sizes, laminate thicknesses, fiber orientations, and a sandwich construction. Results from the energy profiling technique show that the penetration and perforation thresholds increase nearly linearly with the size of the impactor while they increase nonlinearly with the thickness. A sandwich composite made of two glass/epoxy laminates and a foam material is found to have higher energy absorption efficiency than a bonded laminate. Among the five [05/ θ5/05] composite laminates investigated, where θ = 0, 15, 30, 45, and 90, [05/155/05] has the highest resistance to delamination and has the highest penetration and perforation thresholds. All these results clearly indicate the advantages of using the energy profiling technique for the analysis of composite laminates subjected to impact loading.
Reduction and Separation of Carbon Nanotube Bundles Using the P(VDF-TrFE) Copolymer: Nanobundles
Authors: El-Hami Khalil , Matsushige Kazumi
Published: September 2004

A method offering the opportunity to synthesize shortened, spaced and reduced single-walled carbon nanotube (SWCNT) bundles is presented as the effect of the polyvinylidene fluoride and trifluoroethylene P(VDF-TrFE) copolymer on carbon nanotubes. Firstly, the TXRF tool was used to study the purity of the SWCNTs prepared by arc-discharge. The results showed that SWCNTs method contains the catalytic particles such as Fe, Co and Ni used for synthesizing SWCNTs. Secondly, a conventional transmission electron microscopy (TEM) was used in imaging and showing the topography changes between (SWCNT) and (SWCNT)-P(VDF-TrFE) nanocomposite. In our previous paper (El-Hami, K. and Matsushige, K. (2003). Chem. Phys. Lett., 368: 168), we demonstrated that the surface of carbon nanotubes was uniformly coated with P(VDF-TrFE). This paper showed that the P(VDF-TrFE) copolymer tended to intercalate the SWCNT bundles in order to reduce the size of SWCNT bundles and separate them, thus the nanobundles appellation.
SiC-AlSi Composite Coatings on Piston Alloys for Diesel Engine Motors
Authors: Igdas V. Turkel , Celik E. , Tekmen C. , Yilmaz F.
Published: September 2004

Plasma spray technique was used to deposit SiC-AlSi composite coatings, having approximate thickness of 400 μm, of commercially available AlSi alloy powders fabricated thereby mixing with SiC particles. The coating microstructure was investigated by a combination of optical microscopy, SEM, EDX and XRD. The coatings had layered morphologies because of deposition and solidification of successive melted or semimelted particles. SiC particles were randomly distributed in AlSi layers. The coatings were subjected to dry sliding wear against hardened steel counterbodies using pin-on-disc type apparatus and microhardness measurement was carried out through a standard microhardness tester. It has been found that these coatings possess porosities, and the hardness values and wear behaviour of the coatings strongly depend on porosity, oxidized, unmelted and semimelted particles.
Residual Compressive Failure Characteristics of Hybrid Composites with Nonwoven Carbon Tissue after Indentation Damage
Authors: Lee Seung-Hwan , Aono Yuuta , Noguchi Hiroshi , Cheong Seong-Kyun
Published: September 2004

The purpose of this study is to investigate the relationship between the low-energy impact damages under static indentation loadings and the residual compressive static and fatigue strengths after damage in hybrid composites with nonwoven carbon tissue (NWCT).

The hybrid laminates are made by interleaving the NWCT layer between the CFRP layer interfaces. The indentation damages were discussed by investigating the delamination areas and the indentation energies of four kinds of angle-ply laminates ([455/ 455/455] and [453/ 453/453/ 453/453] CFRP laminates, and [455// 455//455] and [453// 453//453// 453//453] hybrid laminates; the symbol “//” means that the NWCT layer is located at an interface between the CFRP layers. The delamination areas of the hybrid laminates were reduced to about half of the CFRP’s by the indentation loading (Lee, S.H., Aono, Y., Noguchi, H. and Cheong, S.K. (2003). Damage Mechanism of Hybrid Composites with Non-Woven Carbon Tissue Subjected to Quasi-Static Indentation Loads, Journal of Composite Materials, 37: 333–349).

After the indentation damage, compressive static and fatigue tests are carried out using an anti-buckling guide for the angle-ply laminates. The failure modes of the angle-ply CFRP and hybrid specimens are caused by global buckling under the compressive static loading. However, the failure modes of the angle-ply CFRP and hybrid specimens at Nf <10 6cycles are caused by shearing the damaged part under the compression–compression fatigue loading. Compared with CFRP laminates, compressive fatigue lives of the hybrid laminates were significantly extended in all the stress ranges.

The NWCT interleaving effect is examined based on the observations of the damage in the hybrid specimens after the indentation damage. Also, the compressive static and fatigue failure processes are discussed from the observation of the fracture surfaces of damaged parts and failed appearance of specimens when subjected to the compressive loadings after the indentation damage.
Fracture Behavior of Carbon–Carbon Composites with Cross-Ply Lamination
Authors: Hatta Hiroshi , Denk Lars , Watanabe Takashige , Shiota Ichiro , Aly-Hassan Mohamed S.
Published: September 2004

Tensile fracture behavior of carbon–carbon composites with 0 /90 laminations were examined using double end-notched specimens. In the composites, the volume fractions of the 0 - and 90 -layers were systematically varied to observe the variation of fracture patterns as a function of the shear strength, which increased with the 0 -ply fraction, r. The fracture mode of the notched C–Cs was shown to transfer from Mode I to Mode II when r increased, with the transition occurring at r slightly higher than 0.5. When Mode II fracture occurred, complete notch insensitivity resulted. In contrast, when Mode I fracture was observed, slight notch sensitivity appeared. To evaluate fracture behavior more deeply, compact tension tests were performed. Resultant crack-resistance (R-) curves clearly explain the transition behavior from Mode I to Mode II. The R-curves also suggested that the slight notch sensitivity in the Mode I fracture was due to small scale splitting that appeared near the notch tips.
Effect of Al Content on the Properties and Microstructure of Al2O3–Cu Composite Prepared by Internal Oxidation
Authors: Shuhua Liang , Liang Fang , Lei Xu , Zhikang Fan
Published: September 2004

Combining high-energy milling with internal oxidation, Al2O3–Cu composite was prepared. The effect of Al content on hardness and electrical conductivity of the composite material was studied. The exothermic effect of Al resulting from internal oxidation during fabricating Al2O3–Cu composite was also calculated and discussed. The results show that Al content has a great effect on the properties and microstructure of the Al2O3–Cu composite. When Al content is less than 0.8wt% and the internal oxidation temperature is at 1223 K, the properties of the composite are improved with the increase in Al content. In contrary, the properties of the composite will decrease while the Al content is more than 0.8 wt%. The main reason for this case is the melting of a part of Cu resulting from the greater exothermic effect with increasing Al content. The influence of exothermic effect on the oxidation and sintering temperature is predominant for the specimen preparing procedure. In this context, the choices of heating rate and the internal oxidation temperature should be varied with Al content.
Non-Destructive Evaluation of Carbon Fiber Composite Reinforcement Content
Authors: Dorsey D. J. , Hebner R. , Charlton W. S.
Published: September 2004

The use of light-weight, high-strength composite materials in motors, generators, and energy storage devices has become common as a means to maximize energy density. To ensure reliability, non-destructive and destructive evaluation techniques have been employed to measure the mechanical properties of fabricated components. In carbon fiber-reinforced, polymer matrix composites, mechanical strength is primarily derived from the fiber volume fraction. Due to the lack of a nondestructive method, common techniques for fiber volume determination are currently destructive. In this investigation, a non-destructive method for the measurement of the fiber volume fraction of carbon fiber-reinforced, polymer matrix composites has been developed using cold neutron prompt gamma activation analysis (PGAA). Fiber volume determination is accomplished in this technique by measuring and comparing the carbon and hydrogen content in a given sample (or samples). PGAA is a nuclear analytical technique performed by exposing a sample to neutron radiation. PGAA measurements are non-destructive and can be performed without chemical preparation of the sample. Fiber volumes of several composite coupons have been determined relative to standard samples of known fiber volume and measurements are in good agreement with values predicted by acid digestion tests. Fiber volume measurement using PGAA can potentially be applied to any composite material where the contents of the matrix and reinforcement differ. The technique can also be spatially sensitive, with resolution limited by the dimensions of the neutron beam that is used.
Polypropylene Composites Unidirectionally Reinforced with Polyester Fibers
Authors: Gonzalez-Chi P. I. , May-Hernandez L. H. , Carrillo-Baeza J. G.
Published: September 2004

Polypropylene composites reinforced with continuous and unidirectional polyester fibers were prepared by the powder method. Three different polyester fibers with different mechanical properties were used. The composite mechanical properties showed a clear influence from the synergistic combination of the fiber properties and the material’s unidirectionality. The impregnation process based on a polypropylene powder cloud was studied, and a method to prepare composites was designed. In general, the powder method showed high compatibility leading to high-quality unidirectional composites.
Microstructure and Tensile Strength Properties of Aluminium Alloys Composites Produced by Pressure-Assisted Aluminium Infiltration of Al2O3/SiC Preforms
Authors: Altinkok Necat
Published: September 2004

In this study, a process for the production of aluminium alloy metal– matrix composites (MMCs) by the liquid metal infiltration route was investigated. This process was based on Al2O3/SiC ceramic cake in different SiC that was obtained by chemical process rather than mixing of ceramic powders to obtain porous Al2O3/SiC ceramic foam. This product was heated up in ceramic crucible in the furnace. It was foamed by the effect of heat and as a result Al2O3/SiC ceramic cake was produced. Resulting Al2O3 grains had 3D honeycomb structure and SiC particles were in the alumina grains. Consequently, homogeneous powder mix and porosity were obtained within the cake. The morphology of the powder connections was networking with flaky particles. These flaky alumina particles provided huge amount of porosity, which was desired for ceramic preforms to allow liquid metal flow during infiltration. Resulting high porous ceramic cake (preform) was placed in a sealed die and liquid aluminium was infiltrated by Ar pressure. The obtained structure indicated that alumina and SiC particles were uniformly distributed with the Al-matrix. In addition, the flaky alumina particles were bonded chemically onto the surfaces during foaming process. The infiltration was achieved successfully; microstructure and tensile strength properties of the composites were examined.
A Statistic Model of Mold Filling through Fibrous Structures
Authors: Zhong Wen , Xing Mengqiu , Chen Shaochun
Published: September 2004

Ising’s model, incorporated with Monte Carlo simulation, is applied to the investigation of the mold filling processes. The behavior of a fluid flowing through fibrous structures is determined by both the fiber–fluid interaction within the system and the applied pressure. When the pressure is comparatively small, interaction within the system is found to dominate the flowing behavior, as shown in the behavior of water flowing through the PET fiber mat in the first part of the study. Then, when the applied pressure increases, it produces an effect that exceeds, little by little, that of the interaction within the system, and becomes dominant in determining the flowing behavior of the fluid. And this applies to the behavior of unsaturated polyester resin flowing through glass fiber-woven fabrics, as described in the second part of the study.
Mechanical Property Characterization of a Polymeric Nanocomposite Reinforced by Graphitic Nanofibers with Reactive Linkers
Authors: Xu L. Roy , Bhamidipati Vikram , Zhong Wei-Hong , Li Jiang , Lukehart Charles M. , Lara-Curzio Edgar , Liu Kenneth C. , Lance Michael J.
Published: September 2004

Mechanical property characterization including bending, tensile, and fracture properties for a new functionalized nanofiber/epoxy composite were conducted. Results show that there was only very little increase in mechanical properties of nanocomposites although we used GCNF-ODA reactive linkers to improve the interface. The interfacial stress level of nanocomposites should be much higher than that of traditional composites because of high property mismatch between the nanoscale reinforcement and the matrix. In order to design strong and stiff nanocomposite materials, one should use aligned nanofibers with a relatively large volume or weight fraction. Also, the length of the nanofiber should be long enough and its diameter not very small in order to facilitate the interfacial load transfer mechanism.
Finite Element Simulation of the Fiber–Matrix Debonding in Polymer Composites Produced by a Sliding Indentor: Part I – Normally Oriented Fibers
Authors: Friedrich Klaus , Goda Tibor , Varadi Karoly , Wetzel Bernd
Published: September 2004

To study the contact and debonding behaviors between a CF–PEEK fiber-reinforced polymer composite specimen and a sliding diamond indentor, finite element macro- and micro-models have been developed. Around each fiber, interface elements were introduced in order to detect the tension-type and also the shear-type debondings for different cases. If initial or final debonding has occurred, a “control algorithm” checked the limit strain conditions for the interface elements and changed the material properties according to the actual debonding condition. As a final result, it can be concluded, that the dominant debonding under compression is due to the shear loading conditions.
Finite Element Simulation of the Fiber– Matrix Debonding in Polymer Composites Produced by a Sliding Indentor: Part II – Parallel and Anti-Parallel Fiber Orientation
Authors: Goda Tibor , VÁradi KÁroly , Wetzel Bernd , Friedrich Klaus
Published: September 2004

A debonding simulation technique, based on a series of nonlinear FE evaluations, has been developed to study the contact behavior and the debonding process of unidirectional fiber-reinforced polymer composites subjected to a sliding diamond indentor. In Part I, the normal fiber orientation was studied, while in Part II, the parallel and anti-parallel fiber orientations relative to the sliding direction are analyzed. The technique developed can consider both the shear and the tension type debonding events, and also the effect of friction causing limited debonding. The results show a dominant limited shear type debonding under compression for both fiber orientations.
Failure Modes of Foam Core Sandwich Beams under Static and Impact Loads
Authors: Lim Tae Seong , Lee Chang Sup , Lee Dai Gil
Published: September 2004

In recent times, sandwich structures have been widely used in load bearing structures due to their high specific stiffness and high specific strength. Some sandwich structures, such as those used in high speed transportations, are required to have high impact energy absorption characteristics also. Since sandwich structures can fail in various modes, in this article, the static failure modes and load capabilities of foam core composite sandwich beams composed of E-glass/Epoxy and PVC foam were investigated by both experimental and analytic methods. The static load capabilities and failure modes predicted by the theory of beam on elastic foundation showed good agreement with the three-point bending test results. Using the experimental and analytic results, the static failure mode map was constructed. Also, the impact failure modes and the impact energy absorption characteristics of the sandwich beams were studied by the impact test and the finite element analysis. From the test result, it was found that the face failure mode was favorable for the high impact energy absorption. Using the experimental and finite element analysis results, the impact failure mode map was constructed.
Effects of Selected Variables on Musicians’ Ratings of High-Level Piano Performances
Authors: Wapnick Joel , Ryan Charlene , Lacaille Nathalie , Darrow Alice-Ann
Published: September 2004

The purpose of this study was to ascertain whether judgments of solo performances recorded at a well-known international piano competition would be affected by musical characteristics such as style (classic period versus early 20th-century Russian) and tempo (slow versus fast). Evaluators rated performances on six test items: tone quality, note accuracy, rhythmic accuracy, expressiveness, adherence to style and overall impression. The effects of four between-subjects variables were examined: audio versus audiovisual presentation, undergraduate versus graduate/faculty, gender, and pianists versus non-pianists.

Results from the 227 evaluators revealed main effects for treatment, style and major: audiovisual presentations were rated higher than audio only presentations, performances of Russian music were rated higher than performances of classic music, and pianists rated performances higher than did non-pianists. The treatment effect was due to a significant treatment by major interaction, and applied only to non-pianists. Gender was involved in a number of three- and four-way interactions that are difficult to interpret.

Pearson r correlations were calculated for ratings of the 16 performances on the overall impression test item. The mean correlation for the 120 pairs of ratings was .33 – low but statistically significant. Intraclass correlations revealed no significant differences between the two levels of all four between-subjects variables.
Pre-Service Music Educators’ Perceived Reasons for Preferring Three Foreign and Distinctive Asian Pieces
Authors: Fung C. Victor
Published: September 2004

The purpose of this study was to examine the perceived reasons of pre-service music educators (undergraduate music majors preparing to teach music) for preferring three distinctive pieces with traditional roots in East Asia. The selected pieces were foreign to research participants in the US. Pre-service music educators ( N= 66) listened to a Chinese piece, a Japanese-American piece and a Korean piece. They were asked to choose one piece that they liked and one piece that they disliked and to explain why they made these preference choices. Results indicated non-significant differences for liking or disliking any of the three pieces ( p> .05). Data suggested that ‘dislike’ should be interpreted as ‘least preferred’. Results showed that pre-service music educators’ perceived reasons for preference were mostly analytical, followed by affective and interest/judgmental. Metaphorical and familiarity reasons were relatively unimportant in explaining pre-service music educators’ preference choices among the three pieces.
The Effect of Performing Ensemble Participation on the Ability to Perform and Perceive Expression in Music
Authors: Kinney Daryl W.
Published: September 2004

This study compared collegiate subjects who had participated in high school performing ensembles (participants) with subjects who had not (non-participants) on their ability to perform expressively and to perceive expression in music. In Phase I, subjects ( N = 56) were asked to perform three song selections, expressively and unexpressively, using a keyboard device that required minimal skill. A panel of experts rated recorded performances for expression and accuracy. In Phase II, subjects ( N = 129) listened to 54 randomly selected performances from Phase I and rated each for expression and accuracy. Results indicated that participants performed with significant ( p < .05) differentiation between expressive and unexpressive renderings in Phase I. In Phase II, participants demonstrated a significant difference ( p < .05) between their ratings of expressive and unexpressive performances. No significant difference was found between non-participants’ ratings of performances. Findings suggest that school performing ensemble participation positively influences the performance and perception of musical expression.
Problem-Solving and Creativity: Insights from Students’ Individual Composing Pathways
Authors: Burnard Pamela , Younker Betty Anne
Published: September 2004

Music educators are particularly keen to offer learning opportunities that enhance creativity. How this happens remains something of a mystery. Within an international context, this article reports on a study that used a cross-cultural perspective on creative thinking with a particular focus on examining the link between problem-solving and composing. The study compares the individual composing pathways of a sample of students drawn from a range of data sets that tracked students’ thinking as they composed, in terms of the ways in which problems were perceived, framed and solved. Several common themes were identified across students’ musical backgrounds, age and cultures from Australia, Canada and the UK. One such theme with educational implications was that perceiving a compositional problem and seeking solutions utilize different types of thinking.
Fourth- and Fifth-Grade Students’ Affective Response and Ability to Discriminate between Melody and Improvisation after Receiving Instruction in Singing and/or Playing a Piece in the Blues Style
Authors: Parisi Joseph
Published: September 2004

The purpose of this study was to assess fourth- and fifth-grade students’ (9- and 10-yearolds’) affective response and ability to discriminate between melody and improvisation after receiving instruction in singing and/or playing a piece in the blues style. Subjects ( N= 102) were assigned to one of three equal-sized groups. Group 1 learned to sing a blues melody, group 2 learned to play a blues melody on the recorder, and group 3 subjects acted as the control and were given non-specific instruction in both singing and playing various melodies. Data were gathered as subjects manipulated the dial of the Continuous Response Digital Interface (CRDI) to indicate ‘likeability’ and ‘recognition’ along a positive continuum, while listening to five musical examples. A descriptive analysis of group graphs indicated that groups receiving specific instruction in melodic and improvisatory discrimination responded with a higher level of discriminatory skill and positive affective response.
50 Years of ISME: Four Honorary Presidents - Some Reflections on the Past, Present and Future
Authors: Elliott David J.
Published: September 2004

This article introduces and reflects on the biographies of ISME’s four Honorary Presidents: Leo Kestenberg, Zoltán Kodály, Dimitri Kabalevsky and Frank Callaway. The lenses of modernity and postmodernity are applied in an examination of the relationships among the topics of individuality, community and ‘representation’ in relation to: (a) the four men discussed in this issue; and (b) key issues in music education including the nature of music education ‘foundations’, curriculum development and feminism(s).
Dmitri Borisovich Kabalevsky 1904-1987
Authors: Forrest David
Published: September 2004

This article provides a biographical sketch of the Russian composer and educator D. B. Kabalevsky, a discussion of his philosophy of music and education, and an overview of his music for children. Kabalevsky’s philosophy of education and music encompassed a wide range of ideas that were developed over his life-time. Central to his philosophy is the belief that music and the arts should be accessible to all children and, in turn, to all people.
Frank Callaway 1919-2003
Authors: Meyer John
Published: September 2004

Frank Callaway, the fourth Honorary President of ISME, was a New Zealander who contributed greatly to raising the profile of music education in both that country and Australia. His essentially democratic view of music education was moulded by his teaching experience at King Edward Technical College in Dunedin. At the University of Western Australia he created a school of music which placed the discipline within the orbit of both education and the humanities, as well as later developing professional musical training. The performance of music was an essential component of all of his educational projects. Strongly influenced by Grainger’s advocacy of world music education, he used his international positions as well as the creation of major musical events in his home country to promote the value of cross-cultural interchange.