bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamics of slot‐rectangular spouted beds: Effect of slot configuration on the local flow structure
Authors: Chen Z. , Lim C. J. , Grace J. R.
Published: May 2008

The local flow structure in a slot‐rectangular spouted bed column of 300 mm × 100 mm cross‐section was investigated with slots of equal area but different length‐to‐width ratios. Dead‐zones, spout shapes, and distributions of pressure, particle velocity, and voidage were explored. The local flow structure of the slot‐rectangular spouted bed became similar to conventional spouted beds as the height increased, with spouts from slots of different length‐to‐width ratios approaching similarity in the upper part of the bed. Static bed height was found to have little influence on the flow in the spout at a given level.
Property‐averaging applied to determination of volume contraction in binary‐solid liquid‐fluidized beds
Authors: Escudié Renaud , Epstein Norman
Published: May 2008

This communication examines experimental information from the literature on the volume contraction that can occur when two monocomponent particle species that have a diameter ratio and a buoyancy‐corrected density ratio on opposite sides of unity are subjected to liquid fluidization as a binary mixture. Attempts are made to predict this volume contraction by applying monocomponent bed expansion equations using averaged properties of the binary solids. It was found that this method works better if the equations are anchored to experimental monocomponent voidages by the fractional bed volume change that they predict than if the equations are used directly. However, greater prediction accuracy can be achieved by correlation of the adjustable parameter G of the Westman, Am Ceramic Soc, 19, 127–129, (1936) equation, originally applied to binary packed beds.
Direct simulation of the buoyant rise of bubbles in infinite liquid using level set method
Authors: Yu Zhao , Fan Liang‐Shih
Published: May 2008

In this study, 3‐D level set method is applied to investigate the rise of gas bubbles in infinite liquid domain due to the buoyancy force. A number of typical regimes for single bubble rising are studied, including the ellipsoidal, ellipsoidal cap, spherical cap, and skirted bubbles. The bubble shape and rise velocity predicted by the simulation are compared with the graphical correlations of Grace, Trans. Inst. Chem. Eng., 51, 116–120, (1973) and Bhaga and Weber, J. Fluid Mech., 105, 61–85, (1981). Good agreement is found between the simulation results and the correlations. These simulations cover a wide range of the parameters, including Eo, Mo, and Re, and demonstrate the capability and accuracy of level set method for simulation of bubbles under various conditions with considerable deformation. Finally, simulation results for the coalescence of two bubbles are also presented.
Investigation into the hydrodynamics of gas–solid fluidized beds using particle image velocimetry coupled with digital image analysis
Authors: Laverman Jan Albert , Roghair Ivo , Annaland Martin van Sint , Kuipers Hans
Published: May 2008

The hydrodynamics of a freely bubbling, pseudo 2‐D fluidized bed has been investigated experimentally for different bed aspect ratios at different superficial gas velocities by using Particle Image Velocimetry (PIV) combined with Digital Image Analysis (DIA). Coupling of both non‐invasive measuring techniques allows us to obtain information on both the bubble behaviour and emulsion phase circulation patterns simultaneously. In particular, the combination of DIA with PIV allows to correct for the influence of particle raining through the roof of the bubbles on the time‐averaged emulsion phase velocity profiles.
A novel continuous reactor for catalytic reduction of NOx—fixed bed simulations
Authors: Yang Terris T. , Zhang Tianzhu , Bi Hsiaotao T.
Published: May 2008

A novel dual‐zone fluidized bed reactor was proposed for the continuous adsorption and reduction of NOx from combustion flue gases. The adsorption and reaction behaviour of such a reactor has been simulated in a fixed bed reactor using Fe/ZSM‐5 catalyst and propylene reductant with model flue gases. Fe/ZSM‐5 exhibited acceptable activity at T = 350°C and GHSV = 5000 h−1 when O2 concentration was controlled at levels lower than 1% with a HC to NO molar ratio of about 2:1. XPS and BET surface area measurement revealed the nature of the deactivation of the catalyst. Those performance data demonstrated the feasibility of a continuous dual‐zone fluidized bed reactor for catalytic reduction of NOx under lean operating conditions.
Risk based decision‐making in plant design
Authors: Piccinini Norberto , Demichela Micaela
Published: May 2008

Accidental events that have occurred in chemical and nuclear plants show that the application of technical regulations on its own, even when extremely detailed, does not assure that adequate safety levels are reached and, above all, maintained in time. The paper illustrates, with a simple example, how a risk analysis can be considered as an essential tool for a correct plant design, above all when dealing with major risk installations. In particular the use of the Recursive Operability Analysis is shown, in the phase of accident identification, since it allows to directly draw the logic trees, both Fault and Event Trees for the quantification phase, thus assuring the congruence of the whole analysis.
Study of horizontal sonic gas jets in gas–solid fluidized beds
Authors: Dawe Matthew , Briens Cedric , Berruti Franco
Published: May 2008

Existing jet penetration correlations have all been developed for sub‐sonic gas jets and have been found to perform poorly when employed in sonic and supersonic regimes. In the present study, triboelectric probes were used to measure both the penetration depth and expansion angle of sonic gas jets. Experiments were conducted using nozzles of different size and geometry, different particle types, different injection gases, and different fluidization velocities. All these data were used to develop a new, general correlation to predict the penetration depth of sonic gas jets. The effects of these variables on jet expansion angle were also studied.
Hydrodynamics of a high pressure three‐phase fluidized bed subject to foaming
Authors: Rudkevitch Daniel , Macchi Arturo
Published: May 2008

The effects of pressure and surfactants on the phase holdups and flow regime transition velocities of gas–liquid–solid fluidized beds were investigated. The effect of pressure on the bed phase holdups is significant and more pronounced at larger gas flow rates where pressure has a greater effect on the equilibrium bubble size. The addition of a surfactant leads to an increase in the gas holdup and a lowering of the solids and liquid holdups. The presence of a surfactant with a liquid flow results in shearing of the bubbles across the gas–liquid distributor, limiting the effect of pressure. Finally, for all conditions, gas holdups in the freeboard region were greater than in the bed.
Radioactive particle tracking in a lab‐scale conical fluidized bed dryer containing pharmaceutical granule
Authors: Khanna Pankaj , Pugsley Todd , Tanfara Helen , Dumont Hubert
Published: May 2008

Radioactive particle tracking (RPT) has been used to study the motion of the particulate phase in a bench‐scale conical fluidized bed containing dried pharmaceutical granule. RPT revealed that there is a distinct circulation pattern of the granule with particles moving upwards at high velocities near the centre of the bed and falling slowly near the walls. There was also a localized region near the centre of the bed where particles moved downward rapidly. The particle size distribution (PSD) of the granule had an appreciable impact on particle motion with a wide PSD leading to larger fluctuations in particle velocity as well as poorer granule mixing.
Drift flux modelling of CFB risers
Authors: Patience Gregory S. , Bockrath Richard E.
Published: May 2008

Solids inventory is a critical parameter for catalytic reactors: it impacts the geometrical configuration of the reactor, compressor/blower requirements, and the overall economics of the process. Although significant advances have been made for characterizing the hydrodynamic regimes in gas–solid fluidization, empirical relationships for predicting the solids inventory in risers are largely in the developmental stages. Empirical models are either based on the slip velocity, slip factor or the Richardson–Zaki bed expansion relationship. We propose the drift flux model, commonly for gas–liquid hydrodynamic modelling. The drift flux model accounts for radial variations in the axial velocity profile and void fraction with a distribution parameter, C0, and the relative velocity between the phases with the drift velocity, U2j:

$\langle \varepsilon \rangle = {{U_{\rm g} } \over {C_0 (U_{\rm g} + U_{\rm p} ) + \langle \varepsilon V_{{\rm g}j} \rangle /\langle \varepsilon \rangle }}$

In high density risers, the distribution parameter varies between 1.03 and 1.12. The drift velocity is a function of the product of the particle terminal velocity and varies with solids hold‐up.
Mortality after cure of soft‐tissue sarcoma treated with conservation surgery and radiotherapy
Authors: Guadagnolo B. Ashleigh , Zagars Gunar K. , Ballo Matthew T. , Strom Sara S. , Pollock Raphael E. , Benjamin Robert S.
Published: May 2008

BACKGROUND.

The objective of the current study was to analyze the potential treatment‐related mortality in long‐term survivors of soft‐tissue sarcoma (STS) treated with radiotherapy (RT) and conservation surgery.

METHODS.

Between 1960 and 2000, 629 of 1089 patients treated with conservation surgery and RT for nonmetastatic STS at the University of Texas M. D. Anderson Cancer Center never developed disease recurrence. Long‐term survival and causes of death were evaluated using the person‐years method to determine the standardized mortality ratio (SMR). SMRs were calculated for death from all causes, cancer, and cardiac disease using standard U.S. data.

RESULTS.

The median follow‐up was 13.2 years. The 10‐year, 20‐year, and 30‐year actuarial survival rates were 88%, 69%, and 52%, respectively. The overall all‐case mortality was 1.14 (95% confidence interval [95% CI], 0.98‐1.33). The all‐cause mortality exceeded that expected for female patients with an SMR of 1.48 (95% CI, 1.15‐1.88), patients aged ≤50 years with an SMR of 1.46 (95% CI, 1.06‐1.95), and patients with nonextremity tumors with an SMR of 1.57 (95% CI, 1.15‐2.08). The overall cardiac mortality was not found to be significantly elevated. Overall cancer mortality was also not excessive, with an SMR of 1.33 (95% CI 0.99‐1.66). Subgroup analyses revealed an increased cancer mortality over the population expected for female patients aged ≤50 years with nonextremity tumors.

CONCLUSIONS.

In the current study, survivors of STS who were treated with conservation surgery and RT with or without chemotherapy did not appear to experience significant excess mortality compared with controls from the U.S. general population. Subgroup analyses did demonstrate that females aged ≤50 years at the time of diagnosis with nonextremity primary tumors did have higher all‐cause mortality and this increase may be due to cancer mortality. Cancer 2008. © 2008 American Cancer Society.
A Mesoporous Silica Thin Film as Uptake Host for Guest Molecules with Retarded Release Kinetics
Authors: Suh Myungkoo , Lee Ho‐Jin , Park Jin‐Young , Lee U‐Hwang , Kwon Young‐Uk , Kim Deug Joong
Published: May 2008

Uptake and release processes of various fluorescent rhodamine dyes and antitumor drugs to/from an ordered mesoporous silica film are investigated by means of UV/Vis absorption and fluorescence spectroscopies. The pores in the 160 nm‐thick silica film strongly withdraw the dyes from water, thus allowing the storage of several micrograms of guest molecules per square centimeter of film. The binding equilibrium of the dyes follows a Langmuir‐type adsorption. The dissociation constant, Kd, and the maximum binding amount to the film, ${{\rm{N}}_{{\rm{ads}}}^\infty }$, are determined by fitting the binding curves. The release kinetics of the guests from the film to a simulated body fluid (SBF) solution follows a bimodal first‐order exponential behavior. The release kinetics from the mesoporous thin film is remarkably retarded relative to that from mesoporous powders. Among all the studied dyes, rhodamine 101 is released most slowly, which implies that the release rate depends not only on the interactions between the guests and the silica surface, but also on intermolecular interactions between the guest molecules. Comparison of the release kinetics of different antitumor drugs, such as actinomycin D and mitoxantrone, into an SBF solution shows that mitoxantrone is released much slowly. This slower release is attributed to the positive molecular charge and the formation of dimers in the pores.
Asymmetric Synthesis of a Novel Conformationally Constrained D‐Lysine Analogue with a Piperidine Skeleton
Authors: Etayo Pablo , Badorrey Ramón , Díaz‐de‐Villegas María D. , Gálvez José A.
Published: May 2008

A practical asymmetric synthesis of enantiomerically pure(2R,4R)‐1‐(tert‐butoxycarbonyl)‐4‐[2‐(methoxycarbonylamino)ethyl]pipecolic acid starting from easily accessible (R)‐2‐[(S)‐1,2‐bis(benzyloxy)ethyl]‐1‐[(S)‐1‐phenylethyl]‐4‐piperidone in around 33 % overall yield has been performed. The efficiency of the synthetic strategy developed for the synthesis of this novel conformationally constrained D‐lysine analogue relies on the high‐yielding Wadsworth–Emmons reaction of a 2‐substituted 4‐piperidone and the diastereoselective reduction of the exocyclic C=C double bond at the 4‐position of the piperidine ring.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Super‐Fluorinated Liquid Crystals: Towards the Limits of Polarity
Authors: Kirsch Peer , Binder Werner , Hahn Alexander , Jährling Kai , Lenges Marc , Lietzau Lars , Maillard David , Meyer Volker , Poetsch Eike , Ruhl Andreas , Unger Gerald , Fröhlich Roland
Published: May 2008

Highly fluorinated liquid crystals with unprecedented polarity were obtained by introducing a tetrahydropyran moiety into their mesogenic core structure. The new materials exhibit an unusually favourable combination of mesophase properties, excellent solubility and low rotational viscosity, which renders them highly attractive for application in fast‐switching active matrix LCDs.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Functionalization of Tripodal Scaffold Molecules on Solid Support
Authors: Guarise Cristian , Zaupa Giovanni , Prins Leonard J. , Scrimin Paolo
Published: May 2008

A versatile synthetic approach is described for the functionalization of tripodal scaffold molecules on solid support. Intrinsic problems related to the attachment of tripodal scaffolds to a resin (for example mono‐ vs. polyadducts and intramolecular cyclizations) are studied and solutions are provided. The synthetic approach relies on the use of specific protecting groups in the critical steps of the synthesis. Importantly, however, protecting groups on the scaffold molecule are never used, which significantly facilitates scaffold variation, for instance in combinatorial studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Simulation study of a successive interference cancellation receiver for signal monitoring on a CDMA downlink
Authors: Golanbari Michael , Ford Gary E. , Ready Michael J.
Published: May 2008

A successive interference cancellation (SIC) algorithm is developed for the interception of signals transmitted on a CDMA forward link. The system is modelled after the IS‐95 standard but the results are also applicable to other CDMA systems such as the wideband CDMA (W‐CDMA) and IS‐2000 standards. In realistic systems, the different forward link channels are de‐orthogonalised, leading to performance degradation in conventional matched filter (CMF)‐type receivers. Simulation results indicate that the proposed SIC receiver ameliorates the detrimental effects of de‐orthogonalisation, interference and multipath, exhibiting significant gains in traffic capacity over the capacity of a CMF. The numerical simulations also show that the proposed receiver is relatively insensitive to system imperfections. The techniques developed in this paper can be used for interception, surveillance, reconnaissance or monitoring of CDMA signals; to relax the strict requirements on power control; and to improve the capacity of CDMA systems. Copyright © 2008 John Wiley & Sons, Ltd.
Impact of hip fracture, heart failure and weight loss on the risk of institutionalization of community‐dwelling patients with dementia
Authors: Harboun Marc , Dorenlot Pascale , Cohen Nadia , Steinhagen‐Thiessen Elisabeth , Ankri Joël
Published: May 2008

Objectives

This study sought to identify the influence of medical symptoms and diseases on the risk of nursing home placement in a prospective cohort of newly diagnosed community‐dwelling patients with dementia.

Study design and setting

This study included 348 patients with dementia, consecutively diagnosed, recruited and followed at a geriatric outpatient center (mean age: 81 years, 65.5% with Alzheimer's disease, mean baseline MMSE score: 20.5, mean follow‐up: 20.5 months).

Results

After adjustment for factors commonly associated with institutionalization in this population, hip fracture in the 3 years preceding diagnosis, acute congestive heart failure during follow‐up and weight loss of more than 5% in any year during follow‐up were independently associated with nursing home placement.

Conclusion

This study confirms the independent contribution of specific medical symptoms and diseases to earlier institutionalization of patients with dementia. These results stress the importance of better knowledge of the specific characteristics of hip fracture, weight loss and congestive heart failure in the context of dementia, to make more effective prevention possible in this patient population. Copyright © 2008 John Wiley & Sons, Ltd.
Adenine nucleotide changes in the remnant liver: An early signal for regeneration after partial hepatectomy
Authors: Crumm Sara , Cofan Montserrat , Juskeviciute Egle , Hoek Jan B.
Published: May 2008

Liver regeneration after partial hepatectomy (PHx) is orchestrated by multiple signals from cytokines and growth factors. We investigated whether increased energy demand on the remnant liver after PHx contributes to regenerative signals. Changes in the tissue's energy state were determined from adenine nucleotide levels. Adenosine triphosphate (ATP) levels in remnant livers decreased markedly and rapidly (to 48% of control by 30 seconds post-PHx) and remained significantly lower than those in sham-operated controls for 24 to 48 hours. The ATP decrease was not reflected in corresponding increases in adenosine diphosphate (ADP) and adenosine monophosphate (AMP), resulting in a marked decline in total adenine nucleotides (TAN). We found no evidence of mitochondrial damage or uncoupling of oxidative phosphorylation. Multiple lines of evidence indicated that the decline in TAN was not caused by increased energy demand, but by ATP release from the liver. The extent of ATP loss was identical after 30% or 70% PHx, whereas fasting or hyperglycemia, conditions that greatly alter energy demand for gluconeogenesis, affected the ATP/ADP decline but not the loss of TAN. Presurgical treatment with the α-adrenergic antagonist phentolamine completely prevented loss of TAN, although changes in ATP/ADP were still apparent. Importantly, phentolamine treatment inhibited early signaling events associated with the priming stages of liver regeneration and suppressed the expression of

c-fos

. Pretreatment with the purinergic receptor antagonist suramin also partly suppressed early regenerative signals and

c-fos

expression, but without preventing TAN loss.

Conclusion:

The rapid loss of adenine nucleotides after PHx generates early stress signals that contribute to the onset of liver regeneration. (Hepatology 2008.)
Hepatitis C virus JFH-1 strain infection in chimpanzees is associated with low pathogenicity and emergence of an adaptive mutation
Authors: Kato Takanobu , Choi Youkyung , Elmowalid Gamal , Sapp Ronda K. , Barth Heidi , Furusaka Akihiro , Mishiro Shunji , Wakita Takaji , Krawczynski Krzysztof , Liang Jake T.
Published: May 2008

The identification of the hepatitis C virus (HCV) strain JFH-1 enabled the successful development of infectious cell culture systems. Although this strain replicates efficiently and produces infectious virus in cell culture, the replication capacity and pathogenesis

in vivo

are still undefined. To assess the

in vivo

phenotype of the JFH-1 virus, cell culture–generated JFH-1 virus (JFH-1cc) and patient serum from which JFH-1 was isolated were inoculated into chimpanzees. Both animals became HCV RNA-positive 3 days after inoculation but showed low-level viremia and no evidence of hepatitis. HCV viremia persisted 8 and 34 weeks in JFH-1cc and patient serum–infected chimpanzees, respectively. Immunological analysis revealed that HCV-specific immune responses were similarly induced in both animals. Sequencing of HCV at various times of infection indicated more substitutions in the patient serum–inoculated chimpanzee, and the higher level of sequence variations seemed to be associated with a prolonged infection in this animal. A common mutation G838R in the NS2 region emerged early in both chimpanzees. This mutation enhances viral assembly, leading to an increase in viral production in transfected or infected cells.

Conclusion:

Our study shows that the HCV JFH-1 strain causes attenuated infection and low pathogenicity in chimpanzees and is capable of adapting

in vivo

with a unique mutation conferring an enhanced replicative phenotype. (Hepatology 2008.)
Evaluation of circulating endothelial cells, VEGF and VEGFR2 serum levels in patients with chronic myeloproliferative diseases
Authors: Alonci A , Allegra A , Bellomo G , Penna G , D'Angelo A , Quartarone E , Musolino C
Published: May 2008

Authors evaluated some markers of angiogenetic activity in patients with chronic myeloproliferative diseases (CMDs). In this study by using a cytofluorimetric analysis we evaluated circulating endothelial progenitor cells (EPCs) in patients with chronic myeloproliferative disease. Moreover, in the same group of subjects, we evaluated serum levels of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor‐2 (VEGFR2). In our patients, we have found an increase in the number of endothelial progenitor cells in primary myelofibrosis (PMF) and polycythaemia vera (PV) patients, while an increase of circulating endothelial cells (CECs) was found in all patients with CMD. Moreover, we found higher serum levels of VEGF with respect to control subjects in every group of patients with CMD, and a not significant reduction of VEGFR2 levels in essential thrombocythaemia (ET) patients. A correlation was also found in PV patients between VEGF levels and erythrocyte number and in PMF subjects with the count of white cells. Our data suggest that some markers of angiogenesis are activated in CMD patients and angiogenesis may have a role in the pathophysiology of chronic myeloproliferative disorders. Copyright © 2008 John Wiley & Sons, Ltd.
Lysophosphatidic acid induces ovarian cancer cell dispersal by activating Fyn kinase associated with p120‐catenin
Authors: Huang Ruby Yun‐Ju , Wang Seu‐Mei , Hsieh Chang‐Yao , Wu Jiahn‐Chun
Published: May 2008

Lysophosphatidic acid (LPA), known as the “ovarian cancer activating factor,” is a natural phospholipid involved in important biological functions, such as cell proliferation, wound healing and neurite retraction. LPA causes colony dispersal in various carcinoma cell lines by inducing morphological changes, including membrane ruffling, lamellipodia formation, cell–cell dissociation and single cell migration. However, its effects on cell–cell dissociation and cell–cell adhesion of ovarian cancer cells have not been studied. In our study, we showed that LPA induced sequential events of intercellular junction dispersal and “half‐junction” formation in ovarian cancer SKOV3 cells and that Src‐family kinases were involved in both processes, since the effects were abolished by the selective tyrosine kinase inhibitor PP2. LPA induced rapid and transient activation of Src family kinases, which were recruited to cell–cell junctions by increasing the association with the adherens junction protein p120‐catenin. We identified the Src family kinase, Fyn, as the key component associated with p120‐catenin after LPA stimulation in SKOV3 cells. Our study provides evidence that LPA induces junction dispersal in ovarian cancer SKOV3 cells by activating the Src family kinase Fyn and increasing its association with p120‐catenin at the cell–cell junction. © 2008 Wiley‐Liss, Inc.
Prenatal diagnosis of trisomy 16 mosaicism manifested as pulmonary artery stenosis
Authors: Hidaka Nobuhiro , Yamamoto Nari , Tsukimori Kiyomi , Hojo Satoshi , Suzuki Satoshi O. , Wake Norio
Published: May 2008

Trisomy 16 mosaicism detected at midtrimester amniocentesis is rare and indicative of true fetal mosaicism. We report a case of mosaic trisomy 16 diagnosed by amniocentesis in which the sonographic findings included fetal pulmonary artery stenosis, a single umbilical artery, and early onset fetal growth restriction. The pregnancy was legally terminated. A review of previous reports suggests that abnormalities of outlet tracts are rarely encountered in fetuses with trisomy 16 mosaicism revealed via amniocentesis. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Monochromatic Hamiltonian t‐tight Berge‐cycles in hypergraphs
Authors: Dorbec Paul , Gravier Sylvain , Sárközy Gábor N.
Published: May 2008

In any r‐uniform hypergraph ${\cal{H}}$ for 2 ≤ t ≤ r we define an r‐uniform t‐tight Berge‐cycle of length ℓ, denoted by Cℓ(r, t), as a sequence of distinct vertices v1, v2, … , vℓ, such that for each set (vi, vi + 1, … , vi + t − 1) of t consecutive vertices on the cycle, there is an edge Ei of ${\cal{H}}$ that contains these t vertices and the edges Ei are all distinct for i, 1 ≤ i ≤ ℓ, where ℓ + j ≡ j. For t = 2 we get the classical Berge‐cycle and for t = r we get the so‐called tight cycle. In this note we formulate the following conjecture. For any fixed 2 ≤ c, t ≤ r satisfying c + t ≤ r + 1 and sufficiently large n, if we color the edges of Kn(r), the complete r‐uniform hypergraph on n vertices, with c colors, then there is a monochromatic Hamiltonian t‐tight Berge‐cycle. We prove some partial results about this conjecture and we show that if true the conjecture is best possible. © 2008 Wiley Periodicals, Inc. J Graph Theory 59: 34–44, 2008
MRI in nonischemic acquired heart disease
Authors: Ordovás Karen G. , Reddy Gautham P. , Higgins Charles B.
Published: May 2008

Cardiac MRI applications for diagnosis and follow‐up of patients with acquired heart disease are constantly expanding. This review article presents an overview of the use of cardiac MRI in nonischemic acquired heart disease. The role of MRI in nonischemic acquired heart disease continues to be influenced by perceived capabilities of echocardiography. The applications discussed in this review are: myocardial diseases including cardiomyopathies, arrhythmogenic right ventricular dysplasia and myocarditis; pericardial diseases, especially constrictive pericarditis; cardiac and paracardiac masses; and valvular heart disease. Cine MR is now regarded as the preferred method for evaluation and quantification of right ventricular function. J. Magn. Reson. Imaging 2008;27:1195–1213. © 2008 Wiley‐Liss, Inc.
High signal intensity halo around the carotid artery on maximum intensity projection images of time‐of‐flight MR angiography: A new sign for intraplaque hemorrhage
Authors: Yim Yoo Jeong , Choe Yeon Hyeon , Ko Yonghyeh , Kim Sung Tae , Kim Keon Ha , Jeon Pyoung , Byun Hong Sik , Kim Dong‐Ik
Published: May 2008

Purpose

To evaluate the value of the high signal intensity halo sign as a new marker of a fresh or recent intraplaque hemorrhage on the maximum intensity projection (MIP) images of time‐of‐flight (TOF) MR angiography.

Materials and Methods

A total of 135 consecutive patients were included in this study. High‐resolution MRI using 3‐inch surface coils was performed on a 1.5T scanner before the carotid endarterectomy. TOF MR angiograms and T2‐weighted, T1‐weighted pre‐ and postcontrast fast spin echo images were obtained. The surgical and pathological findings of the carotid artery were analyzed and correlated with the MRI findings.

Results

A total of 42 atheromas (31.1%) had a fresh or recent intraplaque hemorrhage on the surgicopathological findings. A total of 38 (90.5%) of these patients showed high signal intensity halo around the carotid artery on the MIP images of TOF MR angiography. The high signal intensity halo sign, compared with the surgical and histopathological findings, demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 91%, 83%, 72%, and 95%, respectively, with a 95% confidence interval (CI) in the detection of an intraplaque hemorrhage. The multisequence approach suggested the presence of an intraplaque hemorrhage with a sensitivity, specificity, positive predictive value, and negative predictive value of 93%, 85%, 74%, and 96%, respectively, with a 95% CI.

Conclusion

High signal intensity halo around the carotid artery on the MIP images of TOF MR angiography is useful in the noninvasive detection of a fresh or recent carotid intraplaque hemorrhage. J. Magn. Reson. Imaging 2008;27:1341–1346. © 2008 Wiley‐Liss, Inc.
Comparison of lipid‐rich necrotic core size in symptomatic and asymptomatic carotid atherosclerotic plaque: Initial results
Authors: Cappendijk Vincent C. , Kessels Alfons G.H. , Heeneman Sylvia , Cleutjens Kitty B.J.M. , Schurink Geert Willem H. , Welten Rob J.Th.J. , Mess Werner H. , van Suylen Robert‐Jan , Leiner Tim , Daemen Mat J.A.P. , van Engelshoven Jos M.A. , Kooi M. Eline
Published: May 2008

Purpose

To investigate the potential difference in the size of the lipid‐rich necrotic core (LRNC) in carotid plaques of symptomatic patients versus asymptomatic patients. Pathological studies established that a large LRNC is an important feature of vulnerable atherosclerotic plaque. Previously, we have demonstrated a high correlation between semiquantitative analysis of the LRNC size in T1‐weighted (w) turbo field echo (TFE) MR images and histology.

Materials and Methods

Thirty‐seven patients with carotid stenosis >70% with (n = 26) or without (n = 11) symptoms were included. Three independent MR readers quantified the amount of LRNC with a T1w TFE pulse sequence. The relative amount of LRNC (LRNC score) was defined as sum of cross‐sectional area percentages LRNC per carotid plaque.

Results

Interreader agreement for the three MR readers was good, with an intraclass correlation coefficient (ICC, 95% confidence interval [CI]) of 0.72 (0.57–0.83). All three MR readers on average found a larger LRNC in the symptomatic group of patients, although this was not statistically significant. The mean LRNC score was 116 ± 129 and 59 ± 62 for symptomatic and asymptomatic patients, respectively (P = 0.13). Symptomatic patients showed wide ranges in LRNC scores (0–424), while the range was much lower in the asymptomatic group (0–170).

Conclusion

Single‐sequence T1w TFE may be a promising technique to study atherosclerotic plaque at risk of stroke. Larger studies are warranted to confirm these promising results. J. Magn. Reson. Imaging 2008;27:1356–1361. © 2008 Wiley‐Liss, Inc.
Evaluation of neovessels in atherosclerotic plaques of rabbits using an albumin‐binding intravascular contrast agent and MRI
Authors: Cornily Jean‐Christophe , Hyafil Fabien , Calcagno Claudia , Briley‐Saebo Karen C. , Tunstead James , Aguinaldo Juan‐Gilberto S. , Mani Venkatesh , Lorusso Vito , Cavagna Friedrich M. , Fayad Zahi A.
Published: May 2008

Purpose

To test whether B‐22956/1, a novel intravascular contrast agent with a high affinity to serum albumin (Bracco Imaging SpA.), allowed quantifying neovessel and macrophage density in atherosclerotic plaques of rabbits using MRI.

Materials and Methods

A T1‐weighted MRI of the aorta was acquired in 10 rabbits (7 atherosclerotic and 3 control rabbits) before and up to 2 h after intravenous injection of 100 μmol/kg of Gd‐DTPA or 75 μmol/kg of B‐22956/1. Plaque enhancement was measured at different time points. Immunohistochemistry was performed using anti‐CD 31 antibodies and anti‐RAM 11 antibodies to correlate to neovessel and macrophage density, respectively.

Results

MRI showed a significant plaque enhancement 2 h after B‐22956/1 versus Gd‐DTPA in the atherosclerotic group (39.75% versus 9.5%; P < 0.0001. Early atherosclerotic plaques (n = 146) enhancement positively correlates with neovessel density on corresponding histological sections (r = 0.42; P < 0.01). Enhancement of atherosclerotic plaques 2 h after injection of B‐22956/1 correlated with macrophage density (r = 0.71; P < 0.01).

Conclusion

Enhancement of atherosclerotic plaques with MRI correlated with neovessel density at early time points after the injection of B‐22956/1 and with macrophage density, at later time points. Hence, B‐22956/1‐enhanced MRI represents a promising imaging technique for the identification of “high‐risk” plaques. J. Magn. Reson. Imaging 2008;27:1406–1411. © 2008 Wiley‐Liss, Inc.
3D dynamic contrast‐enhanced MRI of rectal carcinoma at 3T: Correlation with microvascular density and vascular endothelial growth factor markers of tumor angiogenesis
Authors: Zhang Xiao Ming , Yu Dexin , Zhang Hong Lei , Dai Yong , Bi Dongsong , Liu Zhiyan , Prince Martin R. , Li Chuanfu
Published: May 2008

Purpose

To determine how dynamic contrast‐enhanced (DCE) MRI at 3T correlates with rectal carcinoma angiogenesis.

Materials and Methods

Three‐dimensional (3D) DCE MRI was performed in 38 patients (23 males, 15 females, mean age 60 years) with histologically‐confirmed rectal carcinoma at 3T. Time‐intensity curves (TICs) were used to measure peak enhancement ratio (ERpeak), time to peak enhancement (Tpeak), first enhancement time (Tfirst‐enhance), and uptake rate for rectal tumor, normal rectal wall, and gluteal muscle. After tumor resection, microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression were determined using immunohistochemistry (IHC) stains on available specimens (N = 24) to correlate with DCE MRI.

Results

Rectal carcinoma showed higher ERpeak (3.0 ± 0.9 vs. 1.9 ± 0.9, P < 0.001), higher uptake rate (2.8 ± 1.5/minute vs. 1.2 ± 0.9/minute, P < 0.001), earlier Tpeak (88 ± 56 seconds vs. 124 ± 72 seconds, P = 0.027), and earlier Tfirst‐enhance (34 ± 6 seconds vs. 40 ± 7 seconds, P = 0.008) than normal rectal wall. Adenocarcinoma had shorter Tpeak compared to signet cell carcinoma (77 ± 48 seconds vs. 160 ± 62 seconds, P = 0.004). Tpeak was negatively correlated with MVD (r = –0.516, P = 0.01) and the mean Tpeak was significantly earlier for the VEGF‐positive group compared to the VEGF‐negative group (57 ± 17 seconds vs. 107 ± 64 seconds, P = 0.021).

Conclusion

DCE MRI parameters help predict rectal tumor angiogenesis measured by MVD and VEGF expression and discriminate malignant from normal tissue. J. Magn. Reson. Imaging 2008;27:1309–1316. © 2008 Wiley‐Liss, Inc.
Inferring origin of vascular supply from tracer arrival timing patterns using bolus tracking MRI
Authors: Christensen Søren , Calamante Fernando , Hjort Niels , Wu Ona , Blankholm Anne Dorte , Desmond Patricia , Davis Stephen , Østergaard Leif
Published: May 2008

Purpose

To investigate the potential of novel postprocessing and visualization techniques to distinguish presence of collateral flow using Bolus Tracking MRI. Collateral blood supply is believed to be of paramount importance in acute stroke, yet clinical evaluation is challenging as the gold standard digital subtraction angiography is often not feasible in the acute scenario.

Materials and Methods

In principle, bolus arrival delay data contains information about the route of blood supply into tissue and hereby presence of collateral flow patterns. We first examined the potential of current clinical bolus tracking protocols to accurately characterize bolus arrival delay. Using the simulation results, we analyzed bolus tracking data from one normal volunteer and one acute stroke patient.

Results

The bolus arrival patterns in the volunteer and in the normal hemisphere of the patient were found to be qualitatively similar and in good agreement with physiology. The bolus was seen to spread from the larger arteries toward the periphery. The stroke hemisphere in the patient indicated a retrograde direction of flow on the cortical mantle consistent with leptomeningeal vessels.

Conclusion

Bolus tracking MRI can likely be used to distinguish collateral flow patterns from normal flow patterns. J. Magn. Reson. Imaging 2008;27:1371–1381. © 2008 Wiley‐Liss, Inc.
A new method for the determination of aortic pulse wave velocity using cross‐correlation on 2D PCMR velocity data
Authors: Fielden Samuel W. , Fornwalt Brandon K. , Jerosch‐Herold Michael , Eisner Robert L. , Stillman Arthur E. , Oshinski John N.
Published: May 2008

Purpose

To evaluate the reproducibility of a new multisite axial pulse wave velocity (PWV) measurement technique that makes use of 2D PCMR data and cross‐correlation analysis.

Materials and Methods

PWV was estimated with MRI in 13 healthy volunteers by a transit‐time technique (TT), a multisite technique utilizing 1D PCMR data in the descending aorta (FOOT), and a new multisite axial technique that uses 2D PCMR data over the ascending, transverse, and descending sections of the aorta (2D‐XC).

Results

No significant difference was observed between PWV measurements values measured by the three techniques. However, 2D‐XC displayed significantly better intertest reproducibility than either the TT or FOOT methodologies. Average percent difference between scans: TT: 15.8% ± 13.4%, FOOT: 21.3% ± 16.9%, 2D‐XC: 7.72% ± 4.73%. P = 0.02 for both 2D‐XC/TT comparison and 2D‐XC/FOOT comparison.

Conclusion

2D‐XC is a more reproducible method than either the established TT or FOOT methods to estimate the aortic PWV. J. Magn. Reson. Imaging 2008;27:1382–1387. © 2008 Wiley‐Liss, Inc.
The erythemal clearness index for Valencia, Spain
Authors: Tena F. , Martínez‐Lozano J. A. , Utrillas M. P. , Marín M. J. , Esteve A. R. , Cañada J.
Published: May 2008

The values of three clearness indices have been measured for the city of Valencia: kt, the clearness index for the whole solar spectrum, ktUV the clearness index for the ultraviolet range, and the erythemal clearness index for the erythemal radiation ktUVER, corresponding to the solar radiation weighted by the erythemal action spectrum on human skin, normalized with respect to the solar constant corresponding to that spectrum. The measurements of ktUV reached values that were approximately 54% of that corresponding to kt, while those of ktUVER were much smaller. Some statistics of the erythemal clearness index have been calculated both for monthly as well as hourly means. The shape of the distribution in both cases was nearly normal, so standard deviation and variance were used to analyse the dispersion of the data. The ratio of the erythemal clearness index and the corresponding solar irradiance was also studied. When only the central hours of the day were considered the relation between the two was markedly linear, giving a correlation coefficient that reached 99%. Copyright © 2008 Royal Meteorological Society
An analytical model of the rotational Raman response function of molecular gases
Authors: Zheltikov A. M.
Published: May 2008

We show that the rotational Raman response function of a molecular gas can be mimicked with a series of time‐ and phase‐shifted harmonic‐oscillator terms damped by Gaussian and exponential factors with time constants related to the parameters of molecular rotations. The proposed model is employed to derive compact analytical solutions illustrating a phase control of molecular rotations by ultrashort laser pulses and describing tailored phase masks implemented by molecular rotations driven by optimally time‐ordered pulse sequences. Copyright © 2008 John Wiley & Sons, Ltd.
Stimuli‐Responsive Chitosan‐graft‐Poly(N‐vinylcaprolactam) as a Promising Material for Controlled Hydrophobic Drug Delivery
Authors: Prabaharan Mani , Grailer Jamison J. , Steeber Douglas A. , Gong Shaoqin
Published: May 2008

A novel type of pH‐ and thermo‐responsive copolymer, chitosan‐graft‐poly(N‐vinylcaprolactam) (chitosan‐g‐PNVCL), was prepared by grafting carboxyl‐terminated poly(N‐vinylcaprolactam) (PNVCL–COOH) chains onto a chitosan backbone as a drug‐delivery carrier. The formation of chitosan‐g‐PNVCL was confirmed by FT‐IR and 1H NMR techniques. Chitosan‐g‐PNVCL showed a definite phase transition at 32 °C as occurs in pure PNVCL. The swelling degree of the chitosan‐g‐PNVCL beads was found to be higher at pH 2.2 than at pH 7.4. Moreover, the swelling degree of the beads decreased with increased environmental temperature. Compared to the chitosan beads, the release profile of chitosan‐g‐PNVCL beads showed a slower and more controlled release of the entrapped ketoprofen. The release behavior of the chitosan‐g‐PNVCL beads was influenced by both the pH and temperature of the medium. The MTT assay showed no obvious cytotoxicity of chitosan‐g‐PNVCL against a human endothelial cell line over a concentration range of 0–400 µg · mL−1. These results suggest that chitosan‐g‐PNVCL could be a potential stimuli‐responsive material for controlled drug delivery, and it may improve the bioavailability, efficacy, and compliance of the encapsulated drugs.

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Influence of novel cycle concepts on the high‐temperature corrosion of power plants
Authors: Bordenet Bettina
Published: May 2008

The aim to reduce CO2 emissions has triggered the evaluation of new cycle concepts for power plants. CO2‐capture concepts are also evaluated to add on new and existing power plants. For combined cycle power plants (CCPP), different cycles are investigated such as integrated gasification (IGCC) or oxy‐fuel firing. Besides the difference in combustion compared to a conventional CCPP, the environmental boundary conditions are changed and will affect the oxidation and corrosion life of the materials in the hot‐gas path of the gas turbine and the heat‐recovery steam generator. For the circulating fluidised bed power plants, the biomass co‐firing and the oxy‐fuel firing are also foreseen for CO2‐emission reduction. The fireside corrosion of the water walls will be influenced by these concepts and the changed fuel. The corrosion risk has been evaluated for two new power plant concepts: combined cycle with exhaust gas recirculation and pulverised coal‐fired boiler with oxy‐fuel firing. Based on this evaluation, the consequences for the testing conditions and the material selection have been discussed in detail.
HVOF coatings for steam oxidation protection
Authors: Agüero A. , Muelas R. , Gonzalez V.
Published: May 2008

In the context of the European project ‘Coatings for Supercritical Steam Cycles’ (SUPERCOAT), the use of steam oxidation resistant coatings on currently available ferritic materials with high creep strength but poor oxidation resistance was investigated in order to allow increase in the operating temperature of steam power plants from 550 to 650 °C. Among the explored coating techniques for this application, chosen on the basis of being potentially appropriate for coating steam turbine components, High Velocity Oxy Fuel (HVOF) thermal spray has resulted in one of the most successful techniques. Different alloyed materials such as FeCrAl, NiCrSiFeB, FeAl, NiCr and FeCr have been deposited, optimized and tested under flowing steam at 650 °C. Characterization of as deposited and tested samples by metallography, SEM‐EDS and XRD was carried out. Some of these coatings form protective pure chromium or aluminium oxides exhibiting excellent behaviour for at least 15 000 h of exposure, whereas others form less stable complex mixed oxides which nevertheless grow at considerably slower rates than the oxides formed on uncoated P92 (9 wt% Cr ferritic steel).
TG–mass spectrometry studies in coating design for supercritical steam turbines
Authors: Pérez F. J. , Castañeda S. I.
Published: May 2008

Ferritic steels in steam turbines for the power industry operate without coatings in the temperature range of 590–600 °C. For higher operation temperatures the substrate has to be replaced or coated, otherwise the ferritic substrate at a temperature of 650 °C develops thick oxide scales that promote sudden turbine blade failure. The advantage of the use of coatings is that coated ferritic steels are much less expensive than austenitic stainless steels or nickel base superalloys. In order to go forward to coatings design, the Thermo‐Calc code was used as a base for the mass spectrometry (MS)‐data. Thermogravimetry (TG)–MS experiments were conducted in a closed steam loop in order to obtain information about the oxyhydroxides formation as reaction between coatings and steam. From those results the role of the different coating element could be established and optimized for the coating durability. An oxidation mechanism based on the TG–MS results is given.
Enthalpy Relaxation of Polymers: On the Possible Role of Liquid‐Crystalline Order
Authors: Andreozzi Laura , Autiero Ciro , Faetti Massimo , Galli Giancarlo , Giordano Marco , Zulli Fabio
Published: May 2008

Isothermal physical ageing experiments were performed by differential scanning calorimetry to probe the enthalpy relaxation in a methacrylate copolymer carrying azobenzene mesogenic side groups. Further evidence of the ability of the configurational entropy model developed by Gomez Ribelles in describing the structural relaxation mechanism of polymers is provided. The trend of the equilibrium structural relaxation time was also determined as a function of the reduced temperature Tg/T. The comparison of the aging dynamics of the copolymer with those of previous analogous copolymers containing different amounts of azobenzene counits allowed us to highlight effects of the liquid‐crystalline nematic order on the properties of structural relaxation.

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Structured Hybrid Nanoparticles via Surface‐Initiated ATRP of Methyl Methacrylate from Ordered Mesoporous Silica
Authors: Audouin Fabrice , Blas Hélène , Pasetto Pamela , Beaunier Patricia , Boissière Cédric , Sanchez Clément , Save Maud , Charleux Bernadette
Published: May 2008

Structured hybrid nanoparticles were synthesized via surface‐initiated atom transfer radical polymerization of MMA from ordered mesoporous silica (OMS) nanoparticles with various morphologies. The design of the OMS particles was adjusted to target either spherical core‐shell or cylindrical morphologies with a mean diameter below 400 nm. The polymer growth via ATRP from the silica surface was well‐controlled as demonstrated by the macromolecular characteristics of the grafted chains. Original hybrid multilayered nanoparticles composed of either a dense silica core or hollow core; an inner OMS shell showing radial orientation of the mesopores and an outer PMMA shell with controlled thickness were successfully prepared.

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