bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudodynamic testing of strain‐softening systems with adaptive time steps
Authors: Bursi Oreste S. , Shing Pui‐Shum B. , Radakovic‐Guzina Zorica
Published: April 2007

A structure may exhibit a severe strain‐softening behaviour when subjected to strong earthquake excitation. Pseudodynamic testing of such structures using an implicit time‐integration algorithm may be conceived of as a problem, since the Newton‐type iterations, which are often required when structural non‐linearity develops, may not converge under these circumstances. An unconditionally stable implicit time‐integration algorithm implemented with Newton‐type iterations is analysed to provide an insight into this problem. A simple convergence condition is derived to detect possible divergence. The condition is shown to be a sufficient criterion for convergence for general multiple‐degree‐of‐freedom structures, and it is used later on to develop an adaptive time‐stepping strategy to avoid divergence under severe strain‐softening conditions. The implementation of this technique for pseudodynamic testing is presented. As demonstrated by numerical examples, the algorithm proves to be effective and reliable.
An inelastic substructure technique for the pseudodynamic test method
Authors: Schneider Stephen P. , Roeder Charles W.
Published: April 2007

An inelastic substructure technique for the pseudodynamic test method is described. This technique requires testing of only a critical component of a multi‐degree‐of‐freedom structure, while the remaining portion is modelled using standard inelastic analytical procedures. This is an economical method to investigate the seismic behaviour of a structure, provided a critical subassembly is found. This paper describes the development of a substructure algorithm which is verified with a numerically simulated test. The method was used to evaluate the seismic performance of moment‐resisting steel frames. Modelling for an eight‐storey, three‐bay frame is discussed, and the boundary conditions between the analytical portion and the experimental component are evaluated. The results indicate that the selection of the critical subassembly was adequate and that the pseudodynamic response was significantly dependent on the behaviour of this experimental component. Furthermore, experimental results suggest that this information would have been difficult to obtain from quasi‐static testing or from standard inelastic dynamic analysis. Therefore, this substructure pseudodynamic technique was an economical tool to investigate the seismic behaviour of ductile frames.
Seismic energy dissipation for cable‐stayed bridges using passive devices
Authors: Ali Hosam‐Eddin M. , Abdel‐Ghaffar Ahmed M.
Published: April 2007

This study assesses analytically the effectiveness, feasibility and limitations of elastic and hysteretic damping augmentation devices, such as elastomeric and lead–rubber bearings, with respect to the dynamic and seismic performance of cable‐stayed bridges. This type of bridge, which has relatively greater flexibility, is more susceptible to undesirable vibrations due to service and environmental loadings than are conventional bridges. Therefore, damping is a very important property. Supplementary damping devices based on the plastic deformation of lead and steel are proposed at critical zones, such as the deck–abutment and deck–tower connections, to concentrate hysteretic behaviour in these specially designed energy absorbers. Inelastic behaviour in primary structural elements of the bridge can therefore be avoided, assuring the serviceability of these cable‐supported bridges. Analytically, three‐dimensional modelling is developed for the bridge and the damping devices, including the bridge geometrical large‐displacement non‐linearity and the local material and geometric non‐linearities of the energy dissipation devices. The effects of various modelling and design parameters of the bridge response are also studied, including the properties, modelling accuracy and location of the devices along the bridge superstructure.

It is shown that an optimum model of the seismic performance of the bridges with these passive control devices can be obtained by balancing the reduction in forces along the bridge against tolerable displacements. Appropriate locations and hysteretic energy dissipation properties of the devices can achieve a significant reduction in seismic‐induced forces, as compared to the case with no dampers added, and relatively better control of displacements. In addition, proper selection of the location of the passive control systems can help redistribute forces along the structure which may provide solutions for retrofitting some existing bridges. However, caution should be exercised in simulating the device response for a reliable bridge structural performance. Moreover, while seismic response of the bridge can be significantly improved with added dampers, their degree of effectiveness also depends on the energy absorption characteristics of the dampers.
2‐D transient soil–surface foundation interaction and wave propagation by time domain BEM
Authors: Takemiya Hirokazu , Fei Guan , Sukeyasu Yoshiki
Published: April 2007

This paper shows an effective implementation of the half‐plane Green function for surface strip impulses (Lamb's problem), which was previously developed in a closed form by the authors, into the time‐domain boundary element method for the analysis of related initial boundary value problems. The time‐stepping algorithm utilizing Heaviside step function makes the solution process free from the Rayleigh wave front singularity. Illustrative analyses performed include that: First, the response due to an impulsive uniform strip loading is dealt with in order to check the accuracy of the present solution and to interpret the associated wave motion in the medium. Second, a rigid massless strip surface foundation is analysed when subjected to various impulsive loadings in vertical, horizontal and rotational directions to observe which wave is most concerned with the respective foundation motion. The field response is also of interest with respect to distance attenuation. Third, the dynamic cross‐interaction between active and passive foundations through soil is investigated when multiple strip foundations are placed separately on a half‐space with a certain distance.
An approach to the seismic design of steel structures based on cumulative damage criteria
Authors: Ballio Giulio , Castiglioni Carlo A.
Published: April 2007

The applicability of Miner's rule to the assessment of cumulative damage of structural details in steel structures under seismic loading is discussed and validated both numerically and experimentally. Starting from this consideration, a seismic design method is proposed that, based on linear elastic dynamic analyses, takes into account a more precise description of the structural behaviour.

The proposed method also leads to the identification of a methodology for the assessment of the q‐factor, based on a comparison of the cumulative damage during an earthquake, estimated by means of dynamic linear and non‐linear analyses. This methodology is discussed with reference to columns of single‐storey buildings, and compared to other methods for the assessment of the q‐factor based on the ductility factor theory.
Prediction of earthquake energy input from smoothed fourier amplitude spectrum
Authors: Kuwamura Hitoshi , Kirino Yasunori , Akiyama Hiroshi
Published: April 2007

This paper attempts to show analytically that the energy‐input spectra of damped SDOF systems and undamped MDOF systems excited by an earthquake motion can be predicted by smoothing the Fourier amplitude spectrum of the base acceleration. The spectral window for smoothing in the frequency domain for a damped SDOF system is identical with the probability density function of the time‐variant or instantaneous vibration frequency resulting from non‐linear hysteresis. The spectral window for an undamped MDOF system is identical with the set of squared participation factors associated with vibration modes. It was found that the increase in damping factor and the increase in participation of higher modes provide wider spectral windows, resulting in more flattened or unaltered energy‐input spectra due to enhanced smoothing effects.
Prediction of the seismic capacity of RC structural walls by non‐parametric multidimensional regression
Authors: Peruš Iztok , Fajfar Peter , Grabec Igor
Published: April 2007

The use of a non‐parametric multidimensional regression is suggested for the prediction of the seismic capacity of reinforced concrete structural walls. This capacity is expressed in terms of the shear strength, drift, ductility and failure mode of the walls. For the application of the method a data base is needed which contains data on the results of tests performed on the structural elements under consideration. The data base used in the study was compiled from the available literature, and includes data from laboratory tests carried out on 262 structural walls. The method was validated by comparing the predicted and test results. A comparison with some available closed‐form empirical predictions has been made. The results show that the accuracy of the predictions obtained by the proposed method is, on average, higher than that provided by existing formulae.

The proposed method has several advantages when compared to closed‐form empirical expressions based on standard linear regression: (1) The relationship between the input and output variables is not selected a priori by a prediction law. (2) It takes into account the currently available data base, which can be updated when new information becomes available. (3) An arbitrary number of input and output variables can be taken into account using the same data base. (4) The method can be applied directly to similar problems in structural and earthquake engineering, wherever a suitable data base is available.
Seismic response statistics of SDOF system to exponentially modulated coloured input: An explicit solution
Authors: Fu Gongkang
Published: April 2007

For single‐degree‐of‐freedom systems, this paper presents an explicit solution of response statistics to earthquake excitation modelled by modulated filtered white noise. The modulation is described by the sum of exponentially decaying functions, accounting for non‐stationarity of strong ground motion. The solution was obtained by analysis in the time domain using the state‐space approach and impulse responses. This solution is reducible to several known solutions for simpler cases. Also, it may be used to develop probabilistic seismic response spectra for design and retrofit of structures, such as highway bridges.
Base uplifting analysis of flexibly supported liquid‐storage tanks
Authors: Malhotra Praveen K.
Published: April 2007

An approximate method is presented for the analysis of earthquake induced uplifting in base plates of unanchored liquid‐storage tanks that are supported directly on flexible soil foundations. The method takes due account of the non‐linearities arising from the continuous variation of base contact area, membrane action and plastic yielding in the base plate. First, an ‘exact’ solution is presented for a uniformly loaded flexibly supported prismatic beam, uplifted by a concentrated force applied at one end. A series of such beams are later used in an approximate model of the base plate. The method is highly efficient and believed to be accurate for the level of uplifts encountered in practice. The results are presented for a range of foundation stiffness, representing loose sandy soils to rigid concrete mat. It is shown that, for the same overturning base moment, the flexibly supported tanks, in comparison with the rigidly supported tanks, experience significantly smaller axial compressive stress, but larger base uplift, foundation penetration, plastic rotation at plate boundary and hoop compressive stress in the tank wall.
Experimental study of base isolation by free rolling rods
Authors: Lin Tsung‐Wu , Chern Ching‐Churn , Hone Chao‐Chi
Published: April 2007

Experimental and analytical studies of base isolation by free rolling rods under basement are described in this paper. The tests of the system, a one‐storey, 326‐kg structure mounted on a set of free rolling rods, is carried out on a 3m × 3m shaking‐table. The dynamic behaviour of the isolated structure is studied and used to verify the analytical results. In the isolation system, the coefficient of kinetic rolling friction, measured at different angular velocities, ranges from 0·0007 to 0·0016. The coefficients are reduced by decreasing the angular velocities. Two earthquakes, a short‐period and a long‐period motion in Taiwan, are utilized as the input signals. The accelerations experienced by the superstructure are decreased by factors of 56 and 60 in comparison with the fixed‐base condition for the two input earthquakes. Also, for each test, the peak relative‐to‐ground displacement of the basement is nearly equal to the peak ground displacement, and the permanent displacement of the basement is present after the end of the earthquake. Finally, tests of the system with a recentring‐force device is undertaken, where a soft spring added to the basement reduces efficiently the permanent displacement. Comparisons show a good agreement between experimental and theoretical results.
Composition of the leaf, flower and fruit volatile oils of Pittosporum tobira (Thunb.) W. T. Aiton grown in three locations in Portugal
Authors: Rodrigues Frederico S. L. M. , Antunes Luisa C. S. , Figueiredo A. Cristina , Costa Monya M. , Pereira João D. Silva , Colaço Renato D. Reis , Miranda Hélder H. S. , Barroso José G. , Pedro Luis G. , Scheffer Johannes J. C.
Published: April 2007

The yields of the essential oils isolated from the aerial parts of Pittosporum tobira grown in three different locations in Lisbon, Portugal, were determined by hydrodistillation; the chemical composition of the volatile oils, isolated by distillation–extraction, was analysed by GC and GC–MS. In the oils of the three aerial parts studied (leaves, flowers and fruits), in total 49 compounds were identified. The oil samples from the different aerial parts of P. tobira were isolated in yields of <0.05–0.17% by volume/fresh weight (v/f.w.). n‐Nonane was the most abundant component of all samples (26–68%) and myrcene (2–24%) was the second most abundant. There were no major differences between the oil compositions for the three collection sites or for the distinct aerial parts. Despite variations in the relative amounts of the main components of the oils isolated from both the leaves and fruits, over time, no main dissimilarities were detected between the collective and individual samples, or between the different collection sites. Copyright © 2007 John Wiley & Sons, Ltd.
Depression and chronic medical illnesses in Asian older adults: the role of subjective health and functional status
Authors: Niti Matthew , Ng Tze‐Pin , Kua Ee Heok , Ho Roger Chun Man , Tan Chay Hoon
Published: April 2007

Objective

Depression in elderly is reportedly associated with a number of specific chronic illnesses. Whether each of these co‐morbid associations results uniquely from disease‐specific psychobiological responses or is mediated by non‐specific factors like subjective health and functional status is unclear.

Method

Analysis of data of 2,611 community‐dwelling Chinese aged 55 and older, including depressive symptoms defined by Geriatric Depression Scale score ≥ 5 and self‐reports of specific chronic illnesses.

Results

The prevalence of depressive symptoms was 13.3%, lower in those without chronic illness (7.5%), and higher in those with illnesses (13.2–24.2%). Crude Odds Ratios (OR) were significantly elevated for hypertension, eye disorders, diabetes, arthritis, ischemic heart disease, asthma/COPD, stroke, osteoporosis, heart failure, thyroid problem, and gastric problem. In multivariable analyses, only asthma/COPD [OR:2.85, 95% Confidence Intervals (CI): 1.36, 5.98], gastric problem (OR:2.64, 95% CI: 1.11, 6.29), arthritis (OR:1.87, 95% CI: 1.02, 3.42) and heart failure (OR:2.11, 95% CI: 0.98, 4.58) remained independently associated with depressive symptoms, after adjusting for comorbidities, subjective health and functional status, cognitive functioning, smoking, alcohol, psychosocial and demographic variables.

Conclusion

Most comorbid associations of depressive symptoms with specific chronic illnesses are explained by accompanying poor self‐reported health and functional status, but some illnesses probably have a direct psychobiological basis. Copyright © 2007 John Wiley & Sons, Ltd.
Prospective randomized clinical trial of the effect of needle size on pain, sample adequacy and accuracy in head and neck fine‐needle aspiration cytology
Authors: Brennan Peter A. , Mackenzie Neil , Oeppen Rachel S. , Kulamarva Gautham , Thomas Gareth J. , Spedding Anne V.
Published: April 2007

Background:

Fine‐needle aspiration cytology (FNAC) is useful in the diagnosis of many conditions of the head and neck. No reported studies have investigated the optimal needle gauge in the head and neck region.

Methods:

This was a prospective randomized trial of 100 patients who required FNAC performed with either a 21G or 23G needle. Discomfort was scored by patients using a visual analogue scale. Sample accuracy was assessed in patients who subsequently had excision biopsy.

Results:

FNAC performed with a 23G needle was less painful (mean ± SE, 1.6 ± 1.01) than FNAC with a 21G needle (3.3 ± 1.94; p < .001). There was no difference in sample adequacy between the 2 needle sizes (p = .59). The sensitivities and specificities of both needles were similar.

Conclusion:

Head and neck FNAC should routinely be performed with a 23G needle, resulting in less patient discomfort, and giving sample adequacy comparable to a conventional 21G needle. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Functional outcomes after surgical reconstruction of the base of tongue using the radial forearm free flap in patients with oropharyngeal carcinoma
Authors: Rieger Jana M. , Zalmanowitz Jana G. , Li Shirley Y. Y. , Sytsanko Anna , Harris Jeffrey , Williams David , Seikaly Hadi
Published: April 2007

Background:

Historically, the prevention of functional morbidity after multimodal treatment for squamous cell carcinoma in patients with large base of tongue lesions has been challenging. The purpose of the present research is to report prospectively collected speech and swallowing outcomes for patients with disease that encompassed half or more of the base of tongue.

Methods:

Speech and swallowing data were gathered at 4 evaluation times that spanned the first year of treatment for 32 patients treated with surgery and adjuvant radiation therapy.

Results:

Speech intelligibility remained above 90% for most patients. In the early postoperative period, patients with 100% of their base of tongue resected experienced decreased intelligibility, which improved by the half‐way mark of the evaluations. The majority of patients resumed normal oral feeding, with those who lacked dentition needing to puree their food. Modified barium swallow studies revealed that only 3 patients aspirated thin liquid at the final evaluation. Five patients used a feeding tube at some point over the year of evaluation. At the final evaluation, only 3 patients required enteral feeding, with 2 of these using the tube in combination with oral feeding and 1 using the tube for primary nutrition.

Conclusions:

The results of this study suggest that surgical reconstruction of the base of tongue using the radial forearm free flap in patients with large base of tongue lesions can lead to functional speech and swallowing results. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Work risk‐prevention procedures in highway management and maintenance contracts
Authors: Montes Germán Martínez , Gámez Maria del Carmen Rubio , Romero Juan Carlos Rubio , Mondelo Pedro R. , Terres Fernando
Published: April 2007

Following the great focus on and investment into roads by European administrations in recent years, a new area of employment has arisen wherein the majority of activities relating to the maintenance and operation of infrastructures have been outsourced. The participation of private companies, the organization of the various contracts and maintenance services, and infrastructure users' increasing demand for better quality services, mean that awareness needs to be raised about the subject of work risk prevention. The authors, having carried out a comparative analysis of Spain and England (countries that represent models in terms of infrastructure management and financing) present the results that were obtained, paying particular attention to the worker–user–safety triad, which determines all the preventative action and measures that are taken. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 229–244, 2007.
Toward a hybrid model for usability resource allocation in industrial software product development
Authors: Duffy Colleen M. , Duffy Vincent G. , Yen Benjamin P.C.
Published: April 2007

The organizational aspects of user‐centered software development in a financial services company are presented. The financial services industry sector is one of the industrial sectors to embark on the development of computer software as a consumer product. The nature of business in the service sector predisposes it to encounter difficulties in developing software aimed at meeting customer demands. Lack of familiarity and experience with the product design and implementation processes, as well as reliance on usability for acceptance, are major obstacles encountered. Difficulties, insights, and lessons learned regarding organizational ergonomics issues faced by a user‐centered design group are provided, and a hybrid resource distribution model is proposed to guide other service sector companies in their future software development efforts. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 245–262, 2007.
Intracoronary delivery of autologous bone marrow mononuclear cells radiolabeled by 18F‐fluoro‐deoxy‐glucose: Tissue distribution and impact on post‐infarct swine hearts
Authors: Qian Haiyan , Yang Yuejin , Huang Ji , Gao Runlin , Dou Kefei , Yang Guosheng , Li Jianjun , Shen Rui , He Zuoxiang , Lu Minjie , Zhao Shihua
Published: April 2007

Intracoronary injection of the bone marrow‐derived mononuclear cells (MNCs) is emerging as a potentially novel therapy for ischemic heart failure. This study was aimed at assessing the efficacy of intracoronary MNC delivery in the myocardium. The in vivo distribution and myocardial homing of intracoronarily delivered MNCs in experimental Chinese swine with acute myocardial infarction (AMI) created by occlusion of left anterior descending (LAD) coronary artery for 90 min. MNCs radiolabeled with 18F‐fluoro‐deoxy‐glucose (18F‐FDG) were delivered using a coronary catheter into the infarct‐related coronary artery 1 week after AMI. Dual‐nuclide single photon emission computed tomography (SPECT) revealed that 1 h after cell infusion, 6.8 ± 1.8% of 18F‐FDG‐labeled MNCs occurred in the infarcted myocardium with the remaining activity found primarily in the liver and spleen. In the heart, MNCs were detected predominantly in the under‐perfused myocardium. The infused cells retained in the hearts at a rate highly correlated with the under‐perfused lesional sizes. Pathological examination further demonstrated that 6 weeks after infusion, compared to controls, the hearts receiving MNCs exhibited less fibrosis and inflammatory infiltrate, more viable tissue, and higher vascular density. Cardiac function was significantly improved in the MNC‐infused hearts. Thus, 18F‐FDG labeling and dual‐nuclide SPECT imaging is capable of monitoring in vivo distribution and homing of MNCs after intracoronary infusion. MNC coronary delivery may improve cardiac function and positive ventricular remodeling in the heart with AMI. J. Cell. Biochem. 102: 64–74, 2007. © 2007 Wiley‐Liss, Inc.
Ascochlorin suppresses oxLDL‐induced MMP‐9 expression by inhibiting the MEK/ERK signaling pathway in human THP‐1 macrophages
Authors: Kang Jeong Han , Kim June‐Ki , Park Won‐Hwan , Park Kwan‐Kyu , Lee Tae‐Sung , Magae Junji , Nakajima Hiroo , Kim Cheorl‐Ho , Chang Young‐Chae
Published: April 2007

The critical initiating event in atherogenesis involves the invasion of monocytes through the endothelial walls of arteries and the transformation of monocytes from macrophages into foam cells. Human THP‐1 monocytic cells can be induced to differentiate into macrophages by phorbol myristate acetate (PMA) and can then be converted into foam cells by exposure to oxidized low‐density lipoprotein (oxLDL). Also, during a chronic inflammatory response, monocytes/macrophages produce the 92‐kDa matrix metalloproteinase‐9 (MMP‐9) that may contribute to the extravasation, migration, and tissue remolding capacities of the phagocytic cells. Here, we investigate the effect of ascochlorin (ASC), a prenylphenol antiviral compound from the fungus Ascochyta viciae, on oxLDL‐induced MMP‐9 expression and activity in human THP‐1 macrophages. ASC reduced oxLDL‐induced MMP‐9 expression and activity in a time‐dependent and dose‐dependent manner. Also, an analysis of MMP‐9 activity using pharmacologic inhibitors showed that ASC inhibits MMP‐9 activity via the extracellular signal‐regulated kinase 1 and kinase 2 pathways. Our results suggest that ASC may be useful as a potent clinical antiatherogenic agent, a topic of considerable interest in the biological chemistry of chemotherapeutic agents. J. Cell. Biochem. 102: 506–514, 2007. © 2007 Wiley‐Liss, Inc.
The transferrin receptor and the tetraspanin web molecules CD9, CD81, and CD9P‐1 are differentially sorted into exosomes after TPA treatment of K562 cells
Authors: Abache Toufik , Le Naour François , Planchon Sébastien , Harper Francis , Boucheix Claude , Rubinstein Eric
Published: April 2007

Here we show that treatment of K562 cells with the phorbol ester TPA induces the down‐modulation of various surface antigens. Among them, the transferrin receptor (TfR), the tetraspanin CD81, and a CD81‐associated protein, CD9P‐1, were unique in that their expression levels were lower after 24 h incubation than after 3 h. We demonstrated that like the TfR, CD81 was internalized at early times, and was less synthesized at latter times. Despite the association of a fraction of the TfR with CD81, these two molecules were subjected to different fates. TPA increased targeting of CD81 and CD9P‐1 into exosomes but strongly reduced the localization of the TfR in these vesicles. Using this model we have shown that a fraction of CD81 and CD9P‐1 in exosomes comes from a surface pool and that these molecules remain associated in exosomes. However, CD9P‐1 could be targeted to exosomes in the absence of CD81 and of another tetraspanin, CD9. The targeting of CD9 into exosomes did not require palmitoylation of the protein. J. Cell. Biochem. 102: 650–664, 2007. © 2007 Wiley‐Liss, Inc.
Orthogonal natural atomic orbitals form an appropriate one‐electron basis for expanding CASSCF wave functions into localized bonding schemes and their weights
Authors: Bachler Vinzenz
Published: April 2007

Localized bonding schemes and their weights have been obtained for the π‐electron system of nitrone by expanding complete active space self‐consistent field wave functions into a set of Slater determinants composed of orthogonal natural atomic orbitals (NAOs) of Weinhold and Landis (Valency and Bonding: A Natural Bond Orbital Donor‐Acceptor Perspective, 2005). Thus, the derived bonding schemes are close to orthogonal valence bond structures. The calculated sequence of bonding scheme weights accords with the sequence of genuine resonance structure weights derived previously by Ohanessian and Hiberty (Chem Phys Lett 1987, 137, 437), who employed nonorthogonal atomic orbitals. This accord supports the notion that NAOs form an appropriate orthogonal one‐electron basis for expanding complete active space self‐consistent field wave functions into meaningful bonding schemes and their weights. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
The corrosion behaviour of the aluminum alloy 7075/SiCp metal matrix composite prepared by spray deposition
Authors: Cheng Y.L. , Chen Z.H. , Wu H.L. , Wang H.M.
Published: April 2007

Aluminum alloy 7075 and 7075/SiCp (MMC) were prepared by multi‐layer spray deposition method and the corrosion behaviour of them were studied by electrochemical measurements to study the effect of the addition of silicon carbide on the corrosion behaviour of the MMC. The electrochemical noise result shows that the amplitude of the potential noise of the composite is lower than that of the spray deposited 7075 alloy. The potentiodynamic polarization curves results show that both the cathodic oxygen reduction current density and the anodic dissolution current density of the 7075/SiCp MMC are less than those of the 7075 alloy. Thus, the addition of SiC particles increases the corrosion resistance of the MMC. This may be due to that the microstructure of the spray deposited MMC is compact and SiC particles are nonmetallic material, the addition of it minimizes the real corrosion area of the alloy.
High temperature alloy chloridation at 850°C. Part I: Comparison of Ni‐based and Fe‐based alloy behaviour
Authors: Chevalier S. , Ched'Homme S. , Bekaddour A. , Amilain‐Basset K. , Buisson L.
Published: April 2007

Eight alloys were tested under Ar/Cl2 atmosphere at 850°C for 15 min and 1 h. Their gross and net weights were evaluated together with the base metal consumption. Macroscopic and microscopic micrographs, associated with chemical analyses and X‐ray diffraction gave the composition and microstructure of the corrosion products. Huge differences were observed if one compared the nickel based alloy behaviour to that of the iron based alloy. Molybdenum and tungsten could also play a role, but it was not clearly defined until now. A tentative evaluation of the best candidates will be given, according the experimental conditions of this work and the chosen criteria. A corrosion index was established after each observation and helped to classify the different material behaviour under chloridation. The Ni‐based alloys possessed the best chloridation behaviour in the present conditions, followed by the Ni‐based alloys containing more Cr and finally by the Fe‐based materials. The chloridation behaviours were discussed according to the volatility of the chlorides species formed on the different alloys.
Biomarker discovery in lung cancer—promises and challenges of clinical proteomics
Authors: Bharti Ajit , Ma Patrick C. , Salgia Ravi
Published: April 2007

Lung cancer is a devastating illness with an overall poor prognosis. To effectively address this disease, early detection and novel therapeutics are required. Early detection of lung cancer is challenging, in part because of the lack of adequate tumor biomarkers. The goal of this review is to summarize the knowledge of current biomarkers in lung cancer, with a focus on important serum biomarkers. The current knowledge on the known serum cytokines and tumor biomarkers of lung cancer will be presented. Emerging trends and new findings in the search for novel diagnostic and therapeutic tumor biomarkers using proteomics technologies and platforms are emphasized, including recent advances in mass spectrometry to facilitate tumor biomarker discovery program in lung cancer. It is our hope that validation of these new research platforms and technologies will result in improved early detection, prognostication, and finally the treatment of lung cancer with potential novel molecularly targeted therapeutics. © 2007 Wiley Periodicals, Inc., Mass Spec Rev
Continuous dependence on the geometry and on the initial time for a class of parabolic problems I
Authors: Payne L. E. , Philippin G. A. , Proytcheva V.
Published: April 2007

In this paper, we investigate the continuous dependence on the geometry and the initial time for solutions u(x, t) of a class of nonlinear parabolic initial‐boundary value problems. Copyright © 2007 John Wiley & Sons, Ltd.
Morphology and thermal properties of a PC/PE blend with reactive compatibilization
Authors: Yin Bo , Zhao Yin , Pan Min‐min , Yang Ming‐bo
Published: April 2007

Reactive compatibilization of immiscible polymers is becoming increasingly important and hence a representative study of a polycarbonate/high density polyethylene (PC/HDPE) system is the focus of this paper. A grafted copolymer PC‐graft‐ethylene‐co‐acrylic acid (PC‐graft‐EAA) was generated as a compatibilizer in situ during processing operation by ester and acid reaction between PC and ethylene‐acrylic acid (EAA) in the presence of the catalyst dibutyl tin oxide (DBTO). As the polyethylene (PE) matrix does not play any part during the synthesis of the copolymer and since PC and EAA are also immiscible, to simplify the system, the influence of this copolymer formation at the interface between PC and EAA on rheological properties, phase morphology, and crystallization behavior for EAA/PC binary blends was first studied. The equilibrium torque increased with the DBTO content increasing in EAA/PC blends on Haake torque rheometer, indicating the in situ formation of the graft copolymer. Scanning electron microscopy (SEM) studies of cryogenically fractured surfaces showed a significant change at the distribution and dispersion of the dispersed phase in the presence of DBTO, compared with the EAA/PC blend without the catalyst. Differential scanning calorimetry (DSC) studies suggested that the heat of fusion of the EAA phase in PC/EAA blends with or without DBTO reduced with the formation of the copolymer compared with pure EAA. Then morphological studies and crystallization behavior of the uncompatibilized and compatibilized blends of PC/PE were studied as functions of EAA phase concentration and DBTO content. Morphological observations in PC/PE blends also revealed that on increasing the EAA content or adding the catalyst DBTO, the number of microvoids was reduced and the interface was intensive as compared to the uncompatibilized PC/PE blends. Crystallization studies indicated that PE crystallized at its bulk crystallization temperature. The degree of crystallinity of PE phase in PC/PE/EAA blends was also reduced with the addition of EAA and DBTO compared to the uncompatibilized blends of PC/PE, indicating the decrease in the degree of crystallinity was more in the presence of PC‐graft‐EAA. Copyright © 2007 John Wiley & Sons, Ltd.
Hepatocyte growth factor and c‐Met expression in pericytes: implications for atherosclerotic plaque development
Authors: Liu Y , Wilkinson FL , Kirton JP , Jeziorska M , Iizasa H , Sai Y , Nakashima E , Heagerty AM , Canfield AE , Alexander MY
Published: April 2007

Intraplaque neovascularization contributes to the progression of atherosclerosis. Our aim is to understand the mobilization of cells and factors involved in this process. We investigated the localization of hepatocyte growth factor (HGF) and its receptor, c‐Met, in human atherosclerotic plaques, together with the effects of HGF on pericyte migration in vitro. Atherosclerotic femoral arterial segments were collected and analysed from 13 subjects who were undergoing lower limb amputation. Pericytes were identified in human lesions using a 3G5 antibody. Immunohistochemical analysis localized HGF mainly around microvessels, in association with some, but not all, CD31‐positive endothelial cells. c‐Met expression was mainly associated with smooth muscle cells and pericytes, around some, but not all, microvessels within the atherosclerotic lesions; no detection was apparent in normal internal mammary arteries. Using RT–PCR, we demonstrated expression of HGF and c‐Met in a rat pericyte cell‐line, TR–PCT1, and in primary pericytes. HGF treatment of TR‐PCT1 cells induced their migration, but not their proliferation, in a dose‐dependent manner (10–100 ng/ml, p < 0.01), an effect mediated by activation of the serine/threonine kinase Akt, shown by western blot analysis. Treating the cells with the PI3K inhibitors Wortmannin (0.1 µM) or LY294002 (10 µM) abolished these effects. This work demonstrates the expression of c‐Met and HGF in human atherosclerotic arteries, in association with SM‐actin‐positive cells and CD‐31‐positive cells, respectively. HGF induces pericyte migration via PI3‐kinase and Akt activation in vitro. HGF and c‐Met may be involved in neovascularization during plaque development, and may recruit pericytes to neovessels. Since pericytes are thought to mechanically stabilize new blood vessels, these factors may function to protect against haemorrhage. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Seasonal variations in the isoflavonoids of Radix Puerariae
Authors: Sibao Chen , Dajian Yang , Shilin Chen , Hongxi Xu , Chan Albert S. C.
Published: April 2007

The variations in isoflavonoid content in Radix Puerariae, the root of Pueraria lobata (Wild) Ohwi, have been examined in order to determine the optimum time to harvest the herb. Total isoflavonoid contents have been analysed by a UV spectrophotometric method whilst HPLC with photodiode array detection has been used to monitor the contents of seven major individual isoflavonoids, namely, 3′‐hydroxypuerarin, puerarin, 3′‐methoxypuerarin, daidzin, genistin, formononetin‐7‐glucoside and daidzein. Ninety‐six samples of Radix Puerariae of different ages and harvested in different months were collected and analysed. The results clearly showed that 3‐year‐old roots harvested in January have the highest yields of isoflavonoid compounds. Moreover, the results obtained by both methods have a strong correlation. This suggested that the simple and fast UV spectrophotometric method could be used for monitoring the phytochemical quality of Radix Puerariae. Copyright © 2007 John Wiley & Sons, Ltd.
Separation and quantification of the cellular thiol pool of pea plants treated with heat, salt and atrazine
Authors: Ivanov Sergei Veselinov , Kerchev Pavel Ivanov
Published: April 2007

A novel procedure for the separation of the cellular thiol pool according to the molecular weight and localization of compounds with sulphydryl groups is presented. This simple and rapid method allows the differentiation of thiols into three major fractions—low molecular weight (LMT, primarily glutathione and free cysteine), protein‐bound (TPT) and pellet‐bound (PBT, associated with cell walls and broken organelles). Moreover, determination of the ratio between surface (readily reactive) thiols (ATG) and those that are more or less buried in the protein structure (BTG) can be achieved. In intact pea leaves, the amounts of the total thiols (LMT + PBT + TPT) varies from 2.5 to 4.8 µmol/g of fresh material. The data for LMT, PBT and TPT were related to each other in the approximate ratio 1:2:7. Treatments of pea plants with high temperature, salinity and low amounts of atrazine affect these sulphydryl types differently. For a greater understanding of the applicability of this method to physiological research, the main mechanisms leading to alterations in the cellular thiol pool are discussed. Furthermore, it is suggested that the proportion of available to buried thiols (ATG/BTG) in proteins could be used as a convenient marker for stress impacts. Copyright © 2007 John Wiley & Sons, Ltd.
Dithiothreitol decreases in vitro activity of ADP‐glucose pyrophosphorylase from leaves of apple (Malus domestica Borkh.) and many other plant species
Authors: Chen Li‐Song , Qi Yi‐Ping
Published: April 2007

Inclusion of dithiothreitol (DTT) in the extraction buffer and pre‐incubation of apple leaf ADP‐glucose pyrophosphorylase (AGPase) with DTT resulted in a decrease in AGPase activity whether the assay was performed in the presence or absence of 3‐phosphoglycerate (PGA). When PGA was included in the pre‐incubation mixture or when pre‐incubation of AGPase with PGA was followed by DTT, the latter did not cause any decrease in AGPase activity. However, once AGPase was decreased by DTT, subsequent incubation of the enzyme with PGA did not reverse the decrease. Pre‐incubation of AGPase from leaves of Arabidopsis thaliana, sorghum, soybean, tobacco, spinach, wheat, barley, tomato and potato, and tubers of potato with DTT, generally caused a decrease in AGPase activity when assayed in the presence of PGA. When assayed in the absence of PGA, however, a diverse response of AGPase was observed among species to pre‐incubation with DTT. The activity of AGPase from potato tubers was increased by DTT; the activity of AGPase from both potato and tomato leaves was not affected by DTT; the activity of AGPase from leaves of other species was decreased by DTT. It is concluded that DTT decreases in vitro activity of AGPase from leaves of apple and many other plant species such that DTT should not be routinely included in the extraction or assay mixture of leaf AGPase. Copyright © 2007 John Wiley & Sons, Ltd.
Ultrasound devulcanization of unfilled natural rubber networks, studied via component molecular mobility
Authors: Massey Joseph L , Parr Jennifer C , Wagler Todd A , von Meerwall Ernst , Hong Chang K , Isayev Avraam I
Published: April 2007

13C NMR solids spectroscopy and transverse relaxation, and 1H relaxation and pulsed‐gradient spin‐echo self‐diffusion measurements at 70 °C were used to study molecular and segmental mobilities in natural rubber before and after sulfur crosslinking, and after subsequent devulcanization using intense ultrasound. NMR relaxation does not clearly distinguish between entangled and crosslinked network mobility, but unentangled sol and oligomeric species are separable within the longer T2 decay components. Ultrasound reactor settings affect the amount of extractable sol generated. Some two‐thirds of the sol is entangled, with number‐average molecular weights (Mn) above 10 000 g mol−1. Samples also contain near 2 wt% of inert light species (Mn < 400 g mol−1); ultrasound is relatively ineffective in producing additional oligomeric material. All proton mobilities increase as more sol is produced, but 13C relaxation, reflecting intramolecular effects, indicates a slight decrease in backbone mobility. In contrast with other rubbers, in natural rubber, neither the glass transition nor the sol diffusion rate is greatly affected by the extent of ultrasound exposure. Comparisons with previous similar work of this laboratory, particularly styrene‐butadiene rubber, are useful in confirming the molecular mechanisms involved. Copyright © 2007 Society of Chemical Industry
Transforming polymer blends into composites: a pathway towards nanostructured materials
Authors: Denchev Zlatan Z , Dencheva Nadya V
Published: April 2007

Polymer blends and polymer‐based composites are two of the most rapidly developing groups of materials being of industrial, as well as of academic, interest. More than a decade ago a new group of polymer materials was introduced, which became known under the name ‘microfibrilar composites’ (MFCs). They were obtained by the transformation of blends of thermoplastic polymers into micro‐ or nanostructured systems by combination of appropriate mechanical and thermal treatments. Since then, the importance of these novel materials, both for theory and for engineering practice, has increased significantly. It is an objective of this review to outline the place of MFCs within the whole variety of polymer‐based composites. Furthermore, the methods of their preparation, the ways of investigating their structure and the relation of the structure and mechanical properties are discussed. Ultimately, an evaluation of the future trends in this exiting interdisciplinary research field is attempted. Copyright © 2007 Society of Chemical Industry
The characterisation of dope dyed poly (ethylene terephthalate)
Authors: Uglea Constantin V. , Stan Viorica N.
Published: April 2007

By analysing the polycondensation of ethylene glycol with dimethyl terephthalate, the influence of 1,4‐aminoanthraquinone dyestuffs on the chemical and molecular properties of dope dyed poly(ethylene terephthalate) has been determined. The results show that dope dyed poly(ethylene terephthalate) differs from the uncoloured polymer by a possession of a higher amount of ‐COOH end groups and diethylene glycol units. The shape and the position of molecular weight distribution curves determined by gel permeation chromatography are also influenced by the soluble dyestuffs used.
Friedal‐craft polymers in electrical applications. (I) Synthesis and evaluation of polymers based on terphenyls and p‐xylylene glycol dime thyl ether
Authors: Paxton J. C. , Tighe B. J.
Published: April 2007

The design and evaluation of Friedel‐Crafts polymers as electrical insulants is discussed with particular reference to materials based on p‐xylylene glycol dimethyl ether and terphenyl. The general synthetic procedure for these applications normally consists of two idealised stages. The first involves the formation of a soluble, linear or branched polymer. The second consists of its conversion, sometimes after isolation and compounding operations, to a cross‐linked material at a controllable rate in a moulding or film‐forming reaction.

A variety of catalysts and reaction conditions were examined, of which SnC14 and the so‐called ball clays (a range of kaolin‐based minerals varying in acidity and iron content) proved to be the most interesting. The structures of the polymers at various stages of the reaction leading to the final cross‐linked product are discussed together with the properties of the resultant materials.
Photoconductivity and photovoltaism in polyvinylcarbazole membranes
Authors: Jones Eurfyl Glynne , Read Gordon
Published: April 2007

The preparation and photo‐electrical properties of free standing water impermeable membranes of polyvinylcarbazole (PVCa) are described. The membranes, with aqueous electrolyte contacts, show ohmic photoconduction when doped with crystal violet (CV) and irradiated with light of wavelengths > 475 nm. Optimum levels of doping, which approach one dye molecule per molecule of polymer, give photocurrent/dark current ratios of 106 with light levels of 175 mW cm−2. On open circuit pH dependent photovoltages > 200 mV are obtained which produce photovoltaic currents > 10−10 A cm−2 under short circuit conditions.

The influence of combinations of tetracyano‐o‐benzoquinone (TCOBQ) and CV is additive but, in contrast to reported findings at high voltage gradients, combinations of tetracyanoquinodimethane (TCNQ) and CV lower the efficiency of the photoconduction process by an order of magnitude. Action spectral studies relate this effect to a photoredox process at the electrolyte‐membrane interface associated with the absorption band at 410nm in TCNQ, and suggest domaines of TCNQ in the polymer.

The role of the sensitiser in the transfer of electrons from the membrane to the electrolyte and across the membrane is discussed and the importance, for efficient electron transfer, of the spacial relationship between CV molecules and the stacked carbazole residues in the PVCa molecules is emphasised.
Studies of the antenna effect in polymer molecules V. Determination of the extent of singlet energy migration in a phenanthrene — Containing polymer by fluorescence quenching
Authors: Holden David A. , Ng Dominic , Guillet James E.
Published: April 2007

A modification of a Stern‐Volmer fluorescence quenching experiment was used to determine the extent of singlet energy migration between phenanthrene chromophores in poly(9‐phenanthrylmethyl methacrylate). This system avoids the problems of nonexponential fluorescence decay, inhomogeneous quencher concentrations and complication by the formation of excimers. The contribution to the distance travelled by the singlet excitation during the excited state lifetime as a result of energy migration was shown to correspond to about a third of the distance diffused by an oxygen molecule during the same time.