bluuebunny/crossref_metadata_2025 huggingface dataset:
Poly(methyl methacrylate) nanoparticles prepared through microwave emulsion polymerization
Authors: Bao Jianjun , Zhang Aimin
Published: July 2004

The emulsifier‐free emulsion polymerization of methyl methacrylate (MMA) was conducted with microwave irradiation. Superfine and monodisperse poly(methyl methacrylate) (PMMA) microspheres were obtained. Microwave irradiation notably promoted the polymerization reaction. This phenomenon was ascribed to the acceleration of the initiator [potassium persulfate (KPS)] decomposition by microwave irradiation. The experimental results revealed that the apparent activation energy of KPS decomposition decreased from 128.3 to 106.0 kJ/mol with microwave irradiation. The average particle size of the prepared PMMA latex was mainly controlled with the MMA concentration; it increased linearly from 103 to 215 nm when the MMA concentration increased from 0 to 0.3 mol/L and then remained almost constant at MMA concentrations of 0.3–1.0 mol/L. The KPS concentration had no effect on the average particle size, but the particle size dispersity was significantly reduced by a high KPS concentration. With a mixed polymerization phase (water/acetone = 1:3 v/v) or a redox initiation system, PMMA nanoparticles were obtained with an average particle size of 45 or 67 nm, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2815–2820, 2004
Hydraulic resistance of rigid polyurethane foams. III. Effect of variation of the concentration of catalysts on foam structure and properties
Authors: Mondal Pravakar , Khakhar D. V.
Published: July 2004

Water blown rigid polyurethane foams are made using dibutyltin dilaurate and triethanol amine as catalysts. The rate of carbon dioxide generation due to the reaction of isocyanate with water and the rate of polymerization are varied by changing the relative proportion of the catalysts keeping the total catalyst concentration fixed. The foams have densities in the range of 134 to 164 kg/m3. Foams are characterized for hydraulic resistance, “closed cell content,” and compressive modulus. A cell window is the lamella of the foam material that separates two adjacent cells. A strut is generated where three windows of three different cells meet. The cell window area and strut width of the foam cells are measured by optical microscopy. It is found that cell window area and strut width decrease and the respective distribution becomes narrower as the proportion of dibutyltin dilaurate in the total amount of the catalysts is increased. The hydraulic resistance and hence threshold pressure of the foams increases with increase in the proportion of dibutyltin dilaurate. The maximum threshold pressure of 1.81 MPa is observed for the foam made with dibutyltin dilaurate alone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2838–2843, 2004
Hydraulic resistance of rigid polyurethane foams. I. Effect of different surfactants on foam structure and properties
Authors: Mondal Pravakar , Khakhar D. V.
Published: July 2004

Foams used in buoyancy applications must resist penetration by water at significant depths of immersion. The behavior of water blown rigid polyurethane foam at different water pressures from 0 to 3 MPa are studied in this work. The effects of different surfactants on the cell structure and hydraulic resistance of the foams are examined. The foams have densities in the range of 145 to 160 kg/m3. With increasing applied hydraulic pressure, it is found that the foams have very small buoyancy losses at low pressures but beyond a threshold pressure, buoyancy losses increase rapidly. The threshold pressures of the foams increase with decrease in cell window area. A cell window is the lamella of the foam material that separates two adjacent cells. The cell sizes of the foam are found to correlate with the size of the air bubbles entrained during initial mixing. Surfactants, which reduce the surface tension of the polyol to the greatest extent, are found to give the finest initial bubbles, smaller cells, and foams with the highest hydraulic resistance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2821–2829, 2004
Shear rheological properties of acrylic copolymers and terpolymers suitable for potentially melt processable carbon fiber precursors
Authors: Bortner Michael J. , Bhanu Vinayak , McGrath James E. , Baird Donald G.
Published: July 2004

In an effort to generate melt processable polyacrylonitrile (PAN) precursor fibers suitable for conversion to carbon fibers, an acrylonitrile/methyl acrylate (AN/MA) copolymer and two acrylonitrile/methyl acrylate/acryloyl benzophenone (AN/MA/ABP) terpolymers were synthesized at molar ratios of 85/15 and 85/14/1, respectively. The termonomer (ABP) was incorporated to accelerate crosslinking via UV irradiation, which serves to prevent relaxation of orientation and flow as the temperature of the fiber is raised during thermooxidative stabilization. Two molecular weights of the terpolymer and one molecular weight of the copolymer were studied to determine the effect of the termonomer, and the effect of molecular weight (MW), on the steady shear viscosity (η) and magnitude of the complex viscosity (η*). A higher rate of increase of η as a function of time was observed for the high MW terpolymer relative to that of the copolymer over the temperature range used. Using a temperature sweep and monitoring levels of η*, a minimum was observed at lower temperatures for both terpolymers. These results suggest that copolymerization with ABP significantly increased the thermally induced kinetics of crosslinking. Comparison of the η and η* data for the low and high MW terpolymers suggested that molecular weight also significantly reduced the melt stability (increased the kinetics of crosslinking). A chemorhelogical correlation was then used to quantify the effects of the termonomer and of molecular weight on the kinetics of crosslinking of the AN terpolymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2856–2865, 2004
Influence of processing on ethylene‐propylene block copolymers: Structure and mechanical behavior
Authors: Maspoch M. Ll. , Gamez‐Perez J. , Gimenez E. , Santana O. O. , Gordillo A.
Published: July 2004

Thin plaques (1, 2, and 3 mm) made of polypropylene homopolymer (iPP) and three ethylene propylene block copolymers (EPBC) with different ethylene content (5.5, 7.4, and 12% in weight) have been obtained by different processing methods (injection molding, injection and annealing, and compression molding). The morphology of the plaques has been studied using polarizing microscopy (PLM), differential scanning calorimetry (DSC), and wide‐angle X‐ray scattering (WAXS). The results have been related with the mechanical properties of the plaques (MD and TD directions) in tension loading tests. We show the influence of the ethylene content, thickness, and processing method and conditions in the final morphology and how they affect the mechanical behavior. This knowledge can be used to tailor the final properties of a piece. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2866–2878, 2004
Copolymers derived from bismaleimide oligomer with active solvent
Authors: Wang Zhen , Deng Pengyang , Gao Lianxun , Ding Mengxian
Published: July 2004

An oligomer from 4, 4′‐bis(maleimido)diphenyl methane and methylenedianiline were dissolved in active solvent N,N‐dimethyl acrylamide in a solid content up to 50–70%; the solution was poured in a sheet‐shaped module and irradiated by 60Co with the dose from 20 to 350 kGy at room temperature. The polymerized sheet was postcured at 180°C to obtain a transparent red‐orange sheet with tensile strength above 100 MPa. The glass transition temperature before and after postcuring was around 100°C and 150–180°C, respectively. Styrene was used along with DMAA to decrease the water absorption for the copolymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2879–2882, 2004
The effect of varied monomer composition on adhesive performance and peeling master curves for acrylic pressure‐sensitive adhesives
Authors: Gower M. D. , Shanks R. A.
Published: July 2004

A group of pressure‐sensitive adhesives were prepared with constant glass transition temperature, using emulsion polymerization. The monomers chosen were butyl acrylate, 2‐ethylhexyl acrylate, and methyl methacrylate, along with a small amount of acrylic acid. The proportion of acrylic acid monomer was held constant for each polymer preparation but acrylic ester monomer levels were varied. The glass transition temperatures of the acrylate copolymers were measured by using differential scanning calorimetry. Drying and weighing the tetrahydrofuran‐insoluble polymer fractions were used to determine the polymer gel fractions. Films of constant coating thickness were applied to poly(ethylene terephthalate) film and adhesive properties (tack and shear) were examined. Peel was examined through the construction of master curves derived from peel tests conducted over a range of temperatures and peel rates. As the 2‐ethylhexyl acrylate content increased, the latex gel fractions were found to increase. With increasing EHA and gel fraction, peel shear was found to increase. When peel force master curves were compared, divergence in peel master curves occurred as peel rates increased where polymers with higher butyl acrylate contents reached greater peel stress values. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2909–2917, 2004
Thermal strain of high strength polyethylene fiber in low temperature
Authors: Yamanaka Atsuhiko , Kitagawa Tooru , Tsutsumi Masayuki , Kashima Toshihiro , Fujishiro Hiroyuki , Ema Kimiko , Izumi Yoshinobu , Nishijima Shigehiro
Published: July 2004

High strength polyethylene fiber (Toyobo, Dyneema® fiber: hereinafter abbreviated to DF) has a negative thermal expansion coefficient. Relation between fiber structure and thermal strain of DF used as reinforcement of DF reinforced plastic (DFRP) for cryogenic use was investigated. The crystallinities and orientation angles of several kinds of polyethylene fibers having different modulus from 15 to 134Gpa (herein after abbreviated to DFs) were measured by NMR and X‐ray. We obtained the parameters of the mechanical series‐parallel model composed of crystal and amorphous by crystallinity and modulus. Thermal expansion coefficients of DFs were estimated by mechanical series‐parallel model. All DFs having different modulus showed negative thermal expansion coefficients in the temperature range from 180 to 300K, and absolute values of those markedly increased by increasing tensile modulus of DF. The estimated thermal expansion coefficients showed negative values, and thermal strains showed a similar curve to observed ones mostly. Average thermal expansion coefficients in the temperature range from 180 to 300K estimated by mechanical model agreed with the observed ones. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2918–2925, 2004
Long‐range dependence and performance in telecom networks
Authors: Conti Pier Luigi , Lijoi Antonio , Ruggeri Fabrizio
Published: July 2004

Telecommunications systems have recently undergone significant innovations. These call for suitable statistical models that can properly describe the behaviour of the input traffic in a network. Here we use fractional Brownian motion (FBM) to model cumulative traffic network, thus taking into account the possible presence of long‐range dependence in the data. A Bayesian approach is devised in such a way that we are able to: (a) estimate the Hurst parameter H of the FBM; (b) estimate the overflow probability which is a parameter measuring the quality of service of a network: (c) develop a test for comparing the null hypothesis of long‐range dependence in the data versus the alternative of short‐range dependence. In order to achieve these inferential results, we elaborate an MCMC sampling scheme whose output enables us to obtain an approximation of the quantities of interest. An application to three real datasets, corresponding to three different levels of traffic, is finally considered. Copyright © 2004 John Wiley & Sons, Ltd.
Understanding endothelin‐1 function during craniofacial development in the mouse and zebrafish
Authors: Clouthier David E. , Schilling Thomas F.
Published: July 2004

Morphogenesis of the face and neck is driven by an intricate relay of signaling molecules and transcription factors organized into hierarchical pathways. The coordinated action of these pathways regulates the development of neural crest cells within the pharyngeal arches, resulting in proper spatiotemporal formation of bone, cartilage, and connective tissue. While the functions of many genes involved in these processes were initially elucidated through the use of knockout technology in the mouse, increasing numbers of zebrafish craniofacial mutants have led to a rapid expansion in the identification of genes involved in craniofacial development. A comparative analysis of signaling pathways involved in these processes between mouse and zebrafish holds the potential not only to pinpoint conserved and therefore crucial gene functions in craniofacial development, but also to rapidly identify and study downstream effectors. These complementary approaches will also allow rapid identification of candidate genes and gene functions disrupted in human craniofacial dysmorphologies. In this brief review, we present a comparative analysis of one molecule involved in craniofacial development, endothelin‐1, a small, secreted protein that is crucial for patterning the neural crest cells that give rise to lower jaw and throat structures. Birth Defects Research (Part C) 72:190–199, 2004. © 2004 Wiley‐Liss, Inc.
The adult hair follicle: Cradle for pluripotent neural crest stem cells
Authors: Sieber‐Blum Maya , Grim Milos
Published: July 2004

This review focuses on the recent identification of two novel neural crest–derived cells in the adult mammalian hair follicle, pluripotent stem cells, and Merkel cells. Wnt1‐cre/R26R compound transgenic mice, which in the periphery express β‐galactosidase in a neural crest–specific manner, were used to trace neural crest cells. Neural crest cells invade the facial epidermis as early as embryonic day 9.5. Neural crest–derived cells are present along the entire extent of the whisker follicle. This includes the bulge area, an epidermal niche for keratinocyte stem cells, as well as the matrix at the base of the hair follicle. We have determined by in vitro clonal analysis that the bulge area of the adult whisker follicle contains pluripotent neural crest stem cells. In culture, β‐galactosidase–positive cells emigrate from bulge explants, identifying them as neural crest–derived cells. When these cells are resuspended and grown in clonal culture, they give rise to colonies that contain multiple differentiated cell types, including neurons, Schwann cells, smooth muscle cells, pigment cells, chondrocytes, and possibly other types of cells. This result provides evidence for the pluripotentiality of the clone‐forming cell. Serial cloning showed that bulge‐derived neural crest cells undergo self‐renewal, which identifies them as stem cells. Pluripotent neural crest cells are also localized in the back skin hair of adult mice. The bulge area of the whisker follicle is surrounded by numerous Merkel cells, which together with innervating nerve endings form slowly adapting mechanoreceptors that transduce steady skin indentation. Merkel cells express β‐galactosidase in double transgenic mice, which confirms their neural crest origin. Taken together, our data indicate that the epidermis of the adult hair follicle contains pluripotent neural crest stem cells, termed epidermal neural crest stem cells (eNCSCs), and one newly identified neural crest derivative, the Merkel cell. The intrinsic high degree of plasticity of eNCSCs and the fact that they are easily accessible in the skin make them attractive candidates for diverse autologous cell therapy strategies. Birth Defects Research (Part C) 72:162–172, 2004. © 2004 Wiley‐Liss, Inc.
Combinatorial transcriptional interaction within the cardiac neural crest: A pair of HANDs in heart formation
Authors: Firulli Anthony B. , Conway Simon J.
Published: July 2004

The cardiac neural crest cells migrate from the rostral dorsal neural folds and populate the branchial arches, which contribute directly to the cardiac‐outflow structures. Although neural crest cell specification is associated with a number of morphogenic factors, little is understood about the mechanisms by which transcription factors actually implement the transcriptional programs that dictate cell migration and later the differentiation into the proper cell types within the great vessels and the heart. It is clear from genetic evidence that members of the paired box family and basic helix‐loop‐helix (bHLH) transcription factors from the twist family of proteins are expressed in and play an important function in cardiac neural crest specification and differentiation. Interestingly, both paired box and bHLH factors can function as dimers and, in the case of twist family bHLH factors, partner choice can clearly dictate a change in transcriptional program. The focus of this review is to consider what role the protein‐protein interactions of these transcription factors may play in determining cardiac neural crest specification and differentiation, and how genetic alteration of transcription factor stoichiometry within the cell may reflect more than a simple null event. Birth Defects Research (Part C) 72:151–161, 2004. © 2004 Wiley‐Liss, Inc.
Resolution of (±)‐ibuprofen using (−)‐brucine as a chiral selector by thin layer chromatography
Authors: Bhushan R. , Gupta Deepak
Published: July 2004

The enantiomeric resolution of (±)‐ibuprofen into its enantiomers was achieved by TLC on silica gel plate using optically pure (−)‐brucine as a chiral selector and acetonitrile–methanol (5:1, v/v) as the solvent system. Spots were located in an iodine chamber. The detection limit was 4.9 µg. The effect of concentration of the chiral selector, temperature and pH on resolution has been studied. Copyright © 2004 John Wiley & Sons, Ltd.
Liberation social psychology: learning from Latin America
Authors: Burton Mark , Kagan Carolyn
Published: July 2004

Liberation Social Psychology (la psicología social de la liberación, LSP) has developed amongst a body of psychologists in Latin America over the last decade. There has been no survey of the field in English, although some of the ideas are of relevance for those working with oppressed groups elsewhere in the world. This article explores the context in which LSP grew from the work of Ignacio Martín‐Baró and was developed by Maritza Montero, amongst others. Within LSP, key concepts emerge, including ‘conscientization’, ‘realismo‐crítico’, ‘de‐ideologization’, a social orientation, ‘the preferential option for the oppressed majorities’ and methodological eclecticism. The application of LSP is explored with reference to three domains. First, it is suggested that community social psychology as practised in some parts of Latin America reflects LSP in its emphasis on social transformation and participatory methods. Second, psycho‐social work with victims of state oppression, which adopts a highly social and societal orientation embodies LSP. Third, social analyses which explicitly adopt socio‐psychological‐political analyses of the social realities confronting countries in Latin America embrace, in different ways, principles and concepts of LSP. Some of the challenges facing LSP are discussed and open dialogue is encouraged between LSP and critical, community and applied social psychologists. Copyright © 2004 John Wiley & Sons, Ltd.
Acute and long‐term clinical and angiographic outcome after S‐Stent implantation: S‐Stent multicenter safety and efficacy trial
Authors: Chan Charles , Lim Yean‐Leng , Santoso Teguh , Tresukosol Damras , Lim Yean‐Teng , Sonoda Shinjo , Fitzgerald Peter
Published: July 2004

The purpose of this study is to demonstrate safety and effectiveness of the S‐Stent in de novo coronary lesions treated with conventional percutaneous coronary balloon angioplasty. Between January 2000 and June 2001, 120 patients were prospectively enrolled at four study centers. Patients were treated with coronary stenting in a total of 137 lesions. Procedural success was achieved in 100% of 137 attempted lesions. Clinical success was 99.8%. In‐hospital mortality was 0.8%; myocardial infarction occurred in 0.8% and stent thrombosis in 0.8%. After stent implantation, the minimal lumen diameter increased from 0.92 ± 0.43 to 2.74 ± 0.36 mm (P < 0.0001) and the percent diameter stenosis decreased from 68.0 ± 16.2 to 4.5 ± 12.0 (P < 0.0001). At 6‐month follow‐up, the percent diameter stenosis was 33.5 ± 21.3 and the angiographic restenosis rate was 16.5%. Target lesion revascularization was required in 12 patients (10.1%). We conclude that the use of S‐Stent for coronary intervention resulted in a high procedural success rate and low angiographic restenosis at 6 months after implantation. Catheter Cardiovasc Interv 2004;62:439–444. © 2004 Wiley‐Liss, Inc.
Effect of stents in reducing restenosis in small coronary arteries: A meta‐analysis
Authors: Vaitkus Paul T.
Published: July 2004

The ability of stents to reduce restenosis was established in larger coronary arteries. Clinical trials of stenting in smaller vessels have yielded conflicting results due in part to their sample sizes. The aim of this meta‐analysis was to increase the statistical power by pooling data from these clinical trials. Trials were identified from Medline search, review of recent cardiology meetings' abstracts, and manual review of bibliographies. Studies were included if they were prospective randomized controlled trials. Endpoints examined included a dichotomized definition of angiographic restenosis, target lesion revascularization (TLR), target vessel revascularization (TVR), or any repeat revascularization. Pooling of data was performed by calculating a Mantel‐Haenszel odds ratio (OR). The analysis included 2,598 patients enrolled in eight clinical trials. Stenting significantly reduced restenosis (OR = 0.62; 95% CI = 0.61–0.63). Concordantly, stenting reduced TLR (OR = 0.49), TVR (OR = 0.90), and any revascularization (OR = 0.48). This meta‐analysis supports the hypothesis that stenting reduces restenosis in small coronary arteries as well as in larger coronary arteries. The apparent discordant result of individual clinical trials was due in part to underpowering related to small sample sizes. Catheter Cardiovasc Interv 2004;62:425–429. © 2004 Wiley‐Liss, Inc.
Current status of rotational atherectomy
Authors: Cavusoglu Erdal , Kini Annapoorna S. , Marmur Jonathan D. , Sharma Samin K.
Published: July 2004

Despite the increasing use of percutaneous transluminal coronary angioplasty and intracoronary stent placement for the treatment of obstructive coronary artery disease, a large subset of coronary lesions cannot be adequately treated with balloon angioplasty and/or intracoronary stenting alone. Such lesions are often heavily calcified or fibrotic and undilatable with the present balloon technology and attempts to treat them with balloon angioplasty or intracoronary stent placement often lead to vessel dissection or incomplete stent deployment with resultant adverse outcomes. Rotational atherectomy remains a useful niche device for the percutaneous treatment of such complex lesions, usually as an adjunct to subsequent balloon angioplasty and/or intracoronary stent placement. In contrast to balloon angioplasty or stent placement that widen the coronary lumen by displacing atherosclerotic plaque, rotational atherectomy removes plaque by ablating the atherosclerotic material, which is dispersed into the distal coronary circulation. Other lesion subtypes amenable to treatment with this modality include ostial and branch‐ostial lesions, chronic total occlusions, and in‐stent restenosis. This review discusses the technique and principles of rotational atherectomy, the various treatment strategies for its use (including adjunctive pharmacotherapy), the lesion‐specific applications for this device, and the complications unique to this modality. Recommendations are also made for its use in the current interventional era. Catheter Cardiovasc Interv 2004;62:485–498. © 2004 Wiley‐Liss, Inc.
Combined fibrinolysis using reduced‐dose alteplase plus abciximab with immediate rescue angioplasty versus primary angioplasty with adjunct use of abciximab for the treatment of acute myocardial infarction: Asia‐Pacific Acute Myocardial Infarction Trial (APAMIT) pilot study
Authors: Wong Aaron , Mak Koon‐Hou , Chan Charles , Koh Tian‐Hai , Lau Kean‐Wah , Lim Tai‐Tian , Lim Soo‐Teik , Wong Philip , Sim Ling‐Ling , Lim Yean‐Teng , Tan Huay‐Cheem , Lim Yean‐Leng
Published: July 2004

We conducted a randomized feasibility pilot study comparing combined fibrinolysis with immediate rescue angioplasty vs. primary angioplasty with adjunctive abciximab in patients with acute myocardial infarction (AMI). Seventy patients with ST segment elevation AMI of ≤ 6 hr were randomized to either 50 mg of alteplase and abciximab (n = 34) or primary angioplasty with adjunctive abciximab (n = 36). Coronary angiography was performed at 60 min in the combined lytic group and TIMI 3 flow was present in 65% of patients as compared to 25% (P = 0.001) in the primary angioplasty group prior to intervention. Treatment success, defined as TIMI 3 flow, was achieved in 83% of patients in the primary angioplasty group (P = 0.075 compared to 65% in combined lytic group before rescue angioplasty). There was no difference in overall treatment success between primary angioplasty and combined lytic group with rescue angioplasty (83% vs. 94%; P = NS). Major adverse cardiac events at 1 month were not significant (15% vs. 11%; P = NS), but there was a trend toward more events in the combined lytic group at 6 months (32% vs. 14%; P = 0.066), particularly in target vessel revascularization. In this feasibility pilot study, high rate of TIMI 3 flow was attained in patients with AMI with both combined fibrinolysis and primary angioplasty with adjunctive abciximab. A larger randomized trial is currently ongoing to compare these two strategies. Cathet Cardiovasc Intervent 2004;62:445–452. © 2004 Wiley‐Liss, Inc.
Clinical outcomes of patent foramen ovale closure for paradoxical emboli without echocardiographic guidance
Authors: Varma Chetan , Benson Lee N. , Warr Matthew R. , Yeo Erik , Yip James , Jaigobin Cheryl S. , Webb Gary , McLaughlin Peter R.
Published: July 2004

The objective of this study was to determine the feasibility of device closure of patent foramen ovale (PFO) for presumed paradoxical emboli without echocardiographic guidance or balloon sizing and the clinical outcome after device closure. Closure of the PFO has been proposed as an alternative to anticoagulation in patients with presumed paradoxical emboli. At present, most centers perform device closure with transesophageal echocardiographic guidance and balloon sizing of the defect. Between May 1998 and April 2002, 92 consecutive patients underwent device closure for a PFO using fluoroscopic monitoring only. Procedural success and major complications were recorded. Follow‐up outcomes were recurrence rate and residual atrial shunting on transthoracic echocardiography. All patients (mean age, 45 ± 13 years; 52% male) had successful device deployment using either the CardioSeal (n = 78) and Amplatzer (n = 14) PFO occluders with no major complications. Mean procedure time and fluoroscopy time was 27 ± 13 and 6 ± 4 min, respectively. One patient had a residual shunt on echocardiography at 1 year. Cumulative event‐free survival for recurrence of paradoxical embolus at 1 year was 97.3% ± 1.8%. This study provides a basis for device closure of PFO becoming a safe, day‐case procedure, resulting in a low rate of residual shunting and recurrent thromboembolic events. Catheter Cardiovasc Interv 2004;62:519–525. © 2004 Wiley‐Liss, Inc.
Noncardiac applications of glycoprotein IIb/IIIa inhibitors
Authors: Almeda Francis Q. , Schaer Gary L.
Published: July 2004

Platelet activation and aggregation have become increasingly recognized as the primary processes involved in the cascade that leads to thrombus formation in atherosclerotic vascular disease. Glycoprotein IIb/IIIa receptor inhibitors (GPI) favorably impact thrombus formation and distal embolization by inhibiting the final common pathway of platelet aggregation. Glycoprotein IIb/IIIa inhibitors have been used effectively in a wide variety of clinical scenarios including unstable angina, non‐ST segment elevation myocardial infarction, ST segment elevation myocardial infarction, and low and high risk percutaneous coronary interventions with and without intracoronary stenting, however there is limited data regarding the use of these potent antiplatelet agents in the setting of extracardiac vascular disease. This article will review the non‐cardiac applications of glycoprotein IIb/IIIa inhibitors in the setting of acute ischemic stroke, carotid and vertebral angioplasty and stenting, acute critical limb ischemia, and percutaneous interventions in peripheral arterial occlusive disease. Catheter Cardiovasc Interv 2004;62:530–538. © 2004 Wiley‐Liss, Inc.
Percutaneous transcatheter retrieval of retained balloon catheter in distal tortuous coronary artery: A modified double‐helix approach
Authors: Hung Chung‐Lieh , Tsai Cheng‐Ting , Hou Charles Jia‐Yin
Published: July 2004

The rapid increase in the incidence of retained components in the coronary arteries during angioplasty raises the question of the optimal approach in these cases. Management extends from simply leaving the fragment behind to aggressive surgical removal. Increasingly, percutaneous approaches are being considered. A new percutaneous two‐guidewire helix method has been reported. We describe a case of successful retrieval of an angioplasty balloon using this approach. Cathet Cardiovasc Intervent 2004;62:471–475. © 2004 Wiley‐Liss, Inc.
Medieval pathfinders in surgical oncology
Authors: Hajdu Steven I.
Published: July 2004

The author discusses 12 pioneer physician‐surgeons and their attempts at practicing surgical oncology. Their lives spanned more than 1000 years during the Middle Ages, and they differed greatly with regard to their education and experience as well as ethnic and religious backgrounds. However, all of these pioneers made early landmark contributions related to the detection, diagnosis, and cancer.
A Phase II trial of gemcitabine for metastatic neuroendocrine tumors
Authors: Kulke Matthew H. , Kim Haesook , Clark Jeffrey W. , Enzinger Peter C. , Lynch Thomas J. , Morgan Jeffrey A. , Vincitore Michele , Michelini Ann , Fuchs Charles S.
Published: July 2004

BACKGROUND

Treatment with traditional cytotoxic chemotherapy regimens containing streptozocin or dacarbazine has resulted in only marginal benefit for patients with metastatic neuroendocrine tumors. The use of these regimens has been further limited by their potential toxicity. Gemcitabine is generally well tolerated and possesses demonstrated activity against a wide range of malignancies. The authors assessed the efficacy of gemcitabine in the treatment of patients with metastatic neuroendocrine tumors.

METHODS

Eighteen patients with metastatic neuroendocrine tumors were treated with gemcitabine administered on a standard weekly schedule. Patients were followed for evidence of toxicity, response, and survival.

RESULTS

Gemcitabine was well tolerated. However, no radiologic or biochemical responses were observed. Although the majority of patients (65%) experienced disease stabilization as their best response to therapy, the overall median survival duration was only 11.5 months.

CONCLUSIONS

The minimal activity of gemcitabine highlighted the need for novel treatment approaches. Cancer 2004. © 2004 American Cancer Society.
Bipolar cells of the mouse retina: A gene gun, morphological study
Authors: Pignatelli Vincenzo , Strettoi Enrica
Published: July 2004

One of the key elements concerning our understanding of the organization of the mouse retina is the complete classification of the various types of bipolar cells. With the present study, we tried to contribute to this important issue. Unfortunately, most of the antibodies that stain specifically bipolar cells in the retina of other mammals hardly work for the retina of the mouse. We succeeded in overcoming this limitation by using a relatively novel technique based on the gene gun transfer of fluorescent dyes to cells. Hence, we were able to stain a considerable number of bipolar cells that could be characterized according to morphological and comparative criteria. We also performed a complete morphometric analysis of a subset of bipolar cells stained by anti–neurokinin‐3 receptor antibodies. We found nine types of cone bipolar cells and one type of rod bipolar cell; these data are consistent with the findings of previous studies on the retinas of other mammals, such as rabbits, rats, and monkeys and with a recent study based on the mouse retina (Ghosh et al. [2004] J Comp Neurol 469:70–82). Our results also confirm the existence of a common structural similarity among mammalian retinas. It remains to be elucidated what is exactly the functional role of the various types of cone bipolar cells and what is the specific contribution they provide to the perception of a given visual stimulus. Most probably, each bipolar cell type constitutes a specialized channel for the computation of a selected component of the visual stimulus. More complex signal coding, involving the coordinated activity of various types of bipolar cells, could also be postulated, as it has been shown for ganglion cells (Meister [1996] Proc Natl Acad Sci U S A 93:609–614). J. Comp. Neurol. 476:254–266, 2004. © 2004 Wiley‐Liss, Inc.
Morphogenesis and regionalization of the medaka embryonic brain
Authors: Kage Takahiro , Takeda Hiroyuki , Yasuda Takako , Maruyama Kouichi , Yamamoto Naoyuki , Yoshimoto Masami , Araki Kazuo , Inohaya Keiji , Okamoto Hiroyuki , Yasumasu Shigeki , Watanabe Kaori , Ito Hironobu , Ishikawa Yuji
Published: July 2004

We examined the morphogenesis and regionalization of the embryonic brain of an acanthopterygian teleost, medaka (Oryzias latipes), by in situ hybridization using 14 gene probes. We compared our results with previous studies in other vertebrates, particularly zebrafish, an ostariophysan teleost. During the early development of the medaka neural rod, three initial brain vesicles arose: the anterior brain vesicle, which later developed into the telencephalon and rostral diencephalon; the intermediate brain vesicle, which later developed into the caudal diencephalon, mesencephalon, and metencephalon; and the posterior brain vesicle, which later developed into the myelencephalon. In the late neural rod, the rostral brain bent ventrally and the axis of the brain had a marked curvature at the diencephalon. In the final stage of the neural rod, ventricles began to develop, transforming the neural rod into the neural tube. In situ hybridization revealed that the brain can be divided into three longitudinal zones (dorsal, intermediate, and ventral) and many transverse subdivisions, on the basis of molecular expression patterns. The telencephalon was subdivided into two transverse domains. Our results support the basic concept of neuromeric models, including the prosomeric model, which suggests the existence of a conserved organization of all vertebrate neural tubes. Our results also show that brain development in medaka differs from that reported in other vertebrates, including zebrafish, in gene‐expression patterns in the telencephalon, in brain vesicle formation, and in developmental speed. Developmental and genetic programs for brain development may be somewhat different even among teleosts. J. Comp. Neurol. 476:219–239, 2004. © 2004 Wiley‐Liss, Inc.
Parallel bandwidth characteristics calculations for thin avalanche photodiodes on a SGI Origin 2000 supercomputer
Authors: Pan Yi , Ierotheou Constantinos S. , Hayat Majeed M.
Published: July 2004

An important factor for high‐speed optical communication is the availability of ultrafast and low‐noise photodetectors. Among the semiconductor photodetectors that are commonly used in today's long‐haul and metro‐area fiber‐optic systems, avalanche photodiodes (APDs) are often preferred over p‐i‐n photodiodes due to their internal gain, which significantly improves the receiver sensitivity and alleviates the need for optical pre‐amplification. Unfortunately, the random nature of the very process of carrier impact ionization, which generates the gain, is inherently noisy and results in fluctuations not only in the gain but also in the time response. Recently, a theory characterizing the autocorrelation function of APDs has been developed by us which incorporates the dead‐space effect, an effect that is very significant in thin, high‐performance APDs. The research extends the time‐domain analysis of the dead‐space multiplication model to compute the autocorrelation function of the APD impulse response. However, the computation requires a large amount of memory space and is very time consuming. In this research, we describe our experiences in parallelizing the code in MPI and OpenMP using CAPTools. Several array partitioning schemes and scheduling policies are implemented and tested. Our results show that the code is scalable up to 64 processors on a SGI Origin 2000 machine and has small average errors. Copyright © 2004 John Wiley & Sons, Ltd.
Surfactant‐Directed Polypyrrole/CNT Nanocables: Synthesis, Characterization, and Enhanced Electrical Properties
Authors: Zhang Xuetong , Zhang Jin , Wang Rongming , Zhu Tao , Liu Zhongfan
Published: July 2004

We describe here a new approach to the synthesis of size‐controllable polypyrrole/carbon nanotube (CNT) nanocables by in situ chemical oxidative polymerization directed by the cationic surfactant cetyltrimethylammonium bromide (CTAB) or the nonionic surfactant polyethylene glycol mono‐p‐nonylphenyl ether (Oπ–10). When carbon nanotubes are dispersed in a solution containing a certain concentration of CTAB or Oπ–10, the surfactant molecules are adsorbed and arranged regularly on the CNT surfaces. On addition of pyrrole, some of the monomer is adsorbed at the surface of CNTs and/or wedged between the arranged CTAB or Oπ–10 molecules. When ammonium persulfate (APS) is added, pyrrole is polymerized in situ at the surfaces of the CNTs (core layer) and ultimately forms the outer shell of the nanocables. Such polypyrrole/CNT nanocables show enhanced electrical properties; a negative temperature coefficient of resistance at 77–300 K and a negative magnetoresistance at 10–200 K were observed.
Photochromism of Novel Molybdate/Alkylamine Composite Thin Films
Authors: Chen Zhaohui , Loo Boon H. , Ma Ying , Cao Yunwei , Ibrahim Amin , Yao Jiannian
Published: July 2004

Novel inorganic/organic composite films of molybdates with photochromic properties have been prepared by self‐assembly using alkylammonium ions as a supramolecular template. Both 1‐hexadecylammonium/polyoxomolybdate (C16‐Mo) and 1‐octadecylammonium/polyoxomolybdate (C18‐Mo) composite films have been successfully fabricated. The elemental analysis and thermal gravimetric analysis show that the main product in the C16‐Mo film was (C16H33NH3)4Mo8O26. The X‐ray diffraction (XRD) results indicate that the composite films were lamellar in nature. The IR, Raman and X‐ray photoelectron spectroscopy (XPS) results show that the polyoxomolybdate anions present as MoO6 octahedra and that the Mo species exists as Mo6+ in the freshly prepared films. The alkyl chains in the 1‐hexadecylammonium chains were linear and the alkyl groups are an all‐trans configuration. Upon UV irradiation of the C16‐Mo films, some Mo6+ was reduced to Mo5+, some ‐NH3+ became ‐NH2 with a concomitant increase in the concentration of ‐OH groups on the molybdate moieties, and the films were colored. Thus, the photochromism of the films involves the reduction of Mo6+ to Mo5+, coupled with a proton transfer from 1‐hexadecylammonium ions to an oxygen atom at the Mo site. In contrast to thin films of transition‐metal oxides, which all show photochromism in the blue region of the electromagnetic spectrum, these composite films show photochromism in the violet region with the greatest absorbance change at 472 nm.
On Superconductivity and Superfluidity (What I Have and Have Not Managed to Do), as well as on the ‘Physical Minimum’ at the Beginning of the 21st Century
Authors: Ginzburg Vitaly L.
Published: July 2004

The question of thermeolectric effects in superconductors is still a particular problem, which evidently emerges only in the presence of a temperature gradient. The well‐known Londons theory yielded much, and is widley employed under certain conditions even nowadays, but is absolutely insufficient and has to be generalized. This problem was solved in the Ψ‐theory of superconductivity by V. L. Ginzburg and L. D. Landau. Together they developed a phenomenological theory of superconductivity in the late 1940s. This theory proposes that those electrons that contribute to superconduction form a superfluid. The superconductor is described by a complex function Ψ called the order parameter, and |Ψ|2 indicates the fraction of electrons that has condensed into a superfluid.

In his Nobel lecture V. L. Ginzburg also gives a ‘list’ of top problems in contemporary physics. Acquaintance with all subjects included in this ‘list’ is what he calls the ‘physical minimum’.
Cover Picture: Morphology and Nanomechanics of Conducting Plastic Crystals (ChemPhysChem 7/2004)
Authors: Volel Maritza , Alarco Pierre‐Jean , Abu‐Lebdeh Yaser , Armand Michel
Published: July 2004

The cover picture shows weakly interacting anions and cations in ionic plastic crystals that are free to rotate in a spherical symmetry and give rise to multiple subphases, as seen by AFM. Here, the compact shape of the cation, which is favourable for the tumbling motion, has been designed by fusing a second carbocycle to a pyrazole ring. For more information read the Article by Armand et al. on p. 1027.
Strategies for reducing online privacy risks: Why consumers read (or don't read) online privacy notices
Authors: Milne George R. , Culnan Mary J.
Published: July 2004

Online privacy notices are intended to promote consumer choice and reduce the risks of disclosing personal information online. However, these effects result only if consumers read and use the information contained in the notices. This study used an online survey of 2,468 U.S. adult Internet users to investigate why online consumers read privacy notices across a variety of situations. We found that reading is related to concern for privacy, positive perceptions about notice comprehension, and higher levels of trust in the notice. This suggests that effective privacy notices serve an important function in addressing risk issues related to e-commerce. We further found that reading privacy notices is only one element in an overall strategy consumers use to manage the risks of disclosing personal information online.
The diagnostic role of signals in the context of perceived risks in online shopping: Do signals matter more on the Web?
Authors: Biswas Dipayan , Biswas Abhijit
Published: July 2004

Four experimental studies examine the differential effects of three signals—retailer reputation, perceived advertising expenses, and warranties—on consumer risk perceptions, across two (online and in-store) shopping conditions. The results of three studies suggest that for products with high non-digital attributes (e.g., shirts and jeans), consumers perceive higher risks in online than in in-store settings. Also, for these types of products, mainly due to the non-availability of other significant cues, consumers tend to rely more on signals as diagnostic cues in online shopping conditions. Effectively, the results of these three studies imply that signals are stronger risk reducers in online than in in-store shopping conditions for products high in non-digital attributes. The fourth study tests the boundary condition whereby the diagnostic effects of signals are diminished for products with high digital attributes (e.g., music CDs).
Co-creation experiences: The next practice in value creation
Authors: Prahalad C.K. , Ramaswamy Venkat
Published: July 2004

Consumers today have more choices of products and services than ever before, but they seem dissatisfied. Firms invest in greater product variety but are less able to differentiate themselves. Growth and value creation have become the dominant themes for managers. In this paper, we explain this paradox. The meaning of value and the process of value creation are rapidly shifting from a product- and firm-centric view to personalized consumer experiences. Informed, networked, empowered, and active consumers are increasingly co-creating value with the firm. The interaction between the firm and the consumer is becoming the locus of value creation and value extraction. As value shifts to experiences, the market is becoming a forum for conversation and interactions between consumers, consumer communities, and firms. It is this dialogue, access, transparency, and understanding of risk-benefits that is central to the next practice in value creation.
Mechanism of Reduction of the Nitrite Ion by CuI Complexes
Authors: Burg Ariela , Lozinsky Evgenia , Cohen Haim , Meyerstein Dan
Published: July 2004

The reaction of Cu+aq with NO2− was studied. The results are consistent with the mechanism: Cu+aq + NO2− →← (Cu+NO2−), K = 140 ± 30 M−1; (Cu+NO2−) + H+ → Cu2+ + NO + OH−, k = 4.6 × 105 M−1s−1. It is proposed that the copper is bound to the nitrogen in the transient complex (Cu+NO2−). In addition, the reaction was studied with (CuILi)+ complexes. The results show that the ligands reduce the value of K and that their effect on k depends on the redox potential of the (CuII/ILi) couple. This reaction is the simplest model for the CuNIR (NIR = Nitric reductase) enzymes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Divergent evolution in fluviokarst landscapes of central Kentucky
Authors: Phillips Jonathan D. , Martin Linda L. , Nordberg Viva G. , Andrews William A.
Published: July 2004

Central Kentucky is characterized by a mixture of karst and ﬂuvial features, typically manifested as mosaic of karst‐rich/channel‐poor (KRCP) and channel‐rich/karst‐poor (CRKP) environments. At the regional scale the location and distribution of KRCP and CRKP areas are not always systematically related to structural, lithological, topographic, or other controls. This study examines the relationship of KRCP and CRKP zones along the Kentucky River gorge area, where rapid incision in the last 1·5 million years has lowered local base levels and modiﬁed slopes on the edge of the inner bluegrass plateau. At the scale of detailed ﬁeld mapping on foot within a 4 km2 area, the development of karst and ﬂuvial features is controlled by highly localized structural and topographic constraints, and can be related to slope changes associated with retreat of the Kentucky River gorge escarpment. A conceptual model of karst/ﬂuvial transitions is presented, which suggests that minor, localized variations are sufﬁcient to trigger a karst–ﬂuvial or ﬂuvial–karst switch when critical slope thresholds are crossed. Copyright © 2004 John Wiley & Sons, Ltd.