bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the anti‐vascular effects of combretastatin in rodent tumours by dynamic contrast enhanced MRI
Authors: Maxwell Ross J. , Wilson John , Prise Vivien E. , Vojnovic Borivoj , Rustin Gordon J. , Lodge Martin A. , Tozer Gillian M.
Published: January 2005

The anti‐vascular effects of the tubulin binding agent, disodium combretastatin A‐4 3‐O‐phosphate (CA‐4‐P), have been investigated in the rat P22 carcinosarcoma by measurements of radiolabelled iodoantipyrine uptake and dynamic contrast‐enhanced MRI. The iodoantipyrine estimates of absolute tumour blood flow showed a reduction from 0.35 to 0.04 ml g−1 min−1 6 h after 10 mg kg−1 CA‐4‐P and to <0.01 ml g−1 min−1 after 100 mg kg−1. Tumour blood flow recovered to control values 24 h after 10 mg kg−1 CA‐4‐P, but there was no recovery by 24 h after the higher dose. Dynamic contrast‐enhanced MR images were obtained at 4.7 T, following injection of 0.1 mmol kg−1 Gd‐DTPA and analysed assuming a model arterial input function. A parameter, Ktrans, which is related to blood flow rate and permeability of the tumour vasculature to Gd‐DTPA, was calculated from the uptake data. Ktrans showed a reduction from 0.34 to 0.11 min−1 6 h after 10 mg kg−1 CA‐4‐P and to 0.07 min−1 after 100 mg kg−1. Although the magnitude of changes in Ktrans was smaller than that in tumour blood flow, the time course and dose‐dependency patterns were very similar. The apparent extravascular extracellular volume fraction, νe, showed a four‐fold reduction 6 h after 100 mg kg−1 CA‐4‐P, possibly associated with vascular shutdown within large regions of the tumour. These results suggest that Ktrans values for Gd‐DTPA uptake into tumours could be a useful non‐invasive indicator of blood flow changes induced by anti‐vascular agents such as combretastatin. Copyright © 2002 John Wiley & Sons, Ltd.
Applications of sliding window reconstruction with cartesian sampling for dynamic contrast enhanced MRI
Authors: d'Arcy J. A. , Collins D. J. , Rowland I. J. , Padhani A. R. , Leach M. O.
Published: January 2005

Applications of dynamic contrast enhanced MR imaging are increasing and require both high spatial resolution and high temporal resolution. Perfusion studies using susceptibility contrast in particular require very high temporal resolution. The sliding window reconstruction is a technique for increasing temporal resolution. It has previously been applied to radial and spiral sampling, but these schemes require extensive correction and interpolation during image reconstruction. Fourier raw data can be reconstructed simply and quickly using the fast fourier transform (FFT). This paper presents a new Fourier‐based sampling scheme and sliding window reconstruction that facilitates fast scanning without needing correction or interpolation. This technique can be used on virtually any MR scanner since it requires no specialized hardware. It is implemented here as a dual gradient echo sequence providing simultaneous T1‐ and T2*‐weighted images with a time resolution of 1.1 s. Copyright © 2002 John Wiley & Sons, Ltd.
Assessing changes in tumour vascular function using dynamic contrast‐enhanced magnetic resonance imaging
Authors: Hayes Carmel , Padhani Anwar R. , Leach Martin O.
Published: January 2005

Dynamic contrast‐enhanced MRI (DCE‐MRI) is widely used in the diagnosis and staging of cancer and is emerging as a promising method for monitoring tumour response to treatment. However, DCE‐MR imaging techniques are still evolving and methods of image analysis remain variable and non‐standard, and range from relative changes in the pattern of enhancement to pharmacokinetic modelling of contrast agent uptake. The combination of results from different institutions is therefore difficult and the sensitivities of different methods have not been compared. The purpose of this study is to investigate correlations between qualitatative and quantitative methods of analysis for DCE‐MR images from breast cancer patients undergoing neo‐adjuvant chemotherapy. Fifteen patients underwent DCE‐MRI examinations before and after one course of chemotherapy. Changes in the temporal pattern of signal enhancement, the rate and amplitude of enhancement and the volume transfer constant of contrast agent between the blood plasma and the extravascular extracellular space (EES), Ktrans, and the EES fractional volume, νe, were determined. In addition, whole tumour region‐of‐interest analysis was compared with histogram analysis to investigate the extent of tumour heterogeneity. It was found that changes in the rate of enhancement correlated strongly with changes in Ktrans values (Kendall's τ = 0.68, P < 0.001). Furthermore, it was found that the shape of the signal enhancement curve only changed when the Ktrans values changed by 50% or more. Median Ktrans values determined following histogram analysis of pixel maps of Ktrans were approximately equal to those determined by whole tumour region‐of‐interest analysis. The absolute change in the Ktrans values correlated negatively with the pre‐treatment values, particularly for responding patients. Thus, for higher pre‐treatment Ktrans values, a greater decrease was observed. Greater changes were observed in the upper extremes of the Ktrans histogram than in the median values after one course of treatment. Copyright © 2002 John Wiley & Sons, Ltd.
Enterprise traffic with a differentiated service mechanism
Authors: Yang Chyan , Fu Chen‐Hua , Tu Yueh‐Heng
Published: January 2005

As an enterprise grows, its network bandwidth requirement also increases dramatically. Network performance of an enterprise will impact its operational performance. How do we efficiently manage an enterprise network's resources in an E‐business era? This research proposes a differentiated service mechanism to manage traffic flows in an enterprise. This mechanism would enhance the performance of an enterprise network and help an enterprise efficiently transmits important information. With a high‐performance enterprise network, the enterprise can then operate more efficiently and improves its competitive capability. Copyright © 2001 John Wiley & Sons, Ltd.
Solution of large‐scale weighted least‐squares problems
Authors: Baryamureeba Venansius
Published: January 2005

A sequence of least‐squares problems of the form miny∥G1/2(AT y−h)∥2, where G is an n×n positive‐definite diagonal weight matrix, and A an m×n (m⩽n) sparse matrix with some dense columns; has many applications in linear programming, electrical networks, elliptic boundary value problems, and structural analysis. We suggest low‐rank correction preconditioners for such problems, and a mixed solver (a combination of a direct solver and an iterative solver). The numerical results show that our technique for selecting the low‐rank correction matrix is very effective. Copyright © 2002 John Wiley & Sons, Ltd.
On the growth factor in Gaussian elimination for generalized Higham matrices
Authors: George Alan , Ikramov Khakim D. , Kucherov Andrey B.
Published: January 2005

A Higham matrix is a complex symmetric matrix A=B+iC, where both B and C are real, symmetric and positive definite. We prove that, for such A, the growth factor in Gaussian elimination is less than 3. Moreover, a slightly larger bound $${3\sqrt{2}}$$ holds true for a broader class of complex matrices A=B+iC, where B and C are Hermitian and positive definite. Copyright © 2002 John Wiley & Sons, Ltd.
A parallel block overlap preconditioning with inexact submatrix inversion for linear elasticity problems
Authors: Kaporin Igor E. , Konshin Igor N.
Published: January 2005

We present a parallel preconditioned iterative solver for large sparse symmetric positive definite linear systems. The preconditioner is constructed as a proper combination of advanced preconditioning strategies. It can be formally seen as being of domain decomposition type with algebraically constructed overlap. Similar to the classical domain decomposition technique, inexact subdomain solvers are used, based on incomplete Cholesky factorization. The proper preconditioner is shown to be near optimal in minimizing the so‐called K‐condition number of the preconditioned matrix. The efficiency of both serial and parallel versions of the solution method is illustrated on a set of benchmark problems in linear elasticity. Copyright © 2002 John Wiley & Sons, Ltd.
The convergence of Jacobi–Davidson iterations for Hermitian eigenproblems
Authors: van den Eshof Jasper
Published: January 2005

Rayleigh quotient iteration is an iterative method with some attractive convergence properties for finding (interior) eigenvalues of large sparse Hermitian matrices. However, the method requires the accurate (and, hence, often expensive) solution of a linear system in every iteration step. Unfortunately, replacing the exact solution with a cheaper approximation may destroy the convergence. The (Jacobi‐) Davidson correction equation can be seen as a solution for this problem. In this paper we deduce quantitative results to support this viewpoint and we relate it to other methods. This should make some of the experimental observations in practice more quantitative in the Hermitian case. Asymptotic convergence bounds are given for fixed preconditioners and for the special case if the correction equation is solved with some fixed relative residual precision. A dynamic tolerance is proposed and some numerical illustration is presented. Copyright © 2002 John Wiley & Sons, Ltd.
H‐self‐adjoint matrices. Application to radiosity
Authors: Leblond Michel
Published: January 2005

In computer graphics, in the radiosity context, a linear system Φx=b must be solved and there exists a diagonal positive matrix H such that H Φ is symmetric. In this article, we extend this property to complex matrices: we are interested in matrices which lead to Hermitian matrices under premultiplication by a Hermitian positive‐definite matrix H. We shall prove that these matrices are self‐adjoint with respect to a particular innerproduct defined on ℂn. As a result, like Hermitian matrices, they have real eigenvalues and they are diagonalizable. We shall also show how to extend the Courant–Fisher theorem to this class of matrices. Finally, we shall give a new preconditioning matrix which really improves the convergence speed of the conjugate gradient method used for solving the radiosity problem. Copyright © 2002 John Wiley & Sons, Ltd.
A combination of potential reduction steps and steepest descent steps for solving convex programming problems
Authors: Shi Yixun
Published: January 2005

This paper studies the possibility of combining interior point strategy with a steepest descent method when solving convex programming problems, in such a way that the convergence property of the interior point method remains valid but many iterations do not request the solution of a system of equations. Motivated by this general idea, we propose a hybrid algorithm which combines a primal–dual potential reduction algorithm with the use of the steepest descent direction of the potential function. The $O(\sqrt{n}\left|{\ln {\epsilon}} \right|)$ complexity of the potential reduction algorithm remains valid but the overall computational cost can be reduced. Our numerical experiments are also reported. Copyright © 2002 John Wiley & Sons, Ltd.
Recording dental caries in archaeological human remains
Authors: Hillson Simon
Published: January 2005

Dental caries is an important condition to record in archaeological collections, but the way in which recording is carried out has a large effect on the way in which the results can be interpreted. In living populations, dental caries is a disease that shows a strong relationship with age. Both the nature of carious lesions and their frequency change with successive age groups from childhood to elderly adulthood. There is also a progression in the particular teeth in the dentition which are most commonly affected and, in general, the molars and premolars are involved much more frequently than the canines and incisors. Lower teeth are usually affected more than upper, although the condition usually involves the right and left sides fairly equally. In the high tooth wear rate populations represented by many archaeological and museum collections, there is a complex relationship between the form of lesions and the state of wear, which adds yet another range of factors to the changing pattern of caries with increasing age. In the same populations, chipping, fracture and anomalous abrasion of teeth are also common, and these contribute similarly to the distribution and forms of carious lesion observed. Amongst the living, the pattern of ante‐mortem tooth loss is important in understanding caries and, in archaeological material, there is also the complicating factor of post‐mortem tooth loss. Finally, there is the question of diagnosis. There are diagnostic problems even in epidemiological studies of living patients and, for archaeological specimens, diagenetic change and the variable preservation of different parts of the dentition add further complications. For all these reasons, it is difficult to define any one general index of dental caries to represent the complete dentition of each individual, which would be universally suitable for studying a full range of collections from archaeological sites or museums. Variation in the nature of collections, their preservation, tooth wear, and ante‐mortem and post‐mortem tooth loss mean that when such a general index appears to differ between sites, there could be many other reasons for this, in addition to any genuine differences in caries incidence and pattern that might have been present. It is suggested here that the best approach is instead to make comparisons separately for each tooth type, age group, sex, lesion type and potential lesion site on the tooth. Copyright © 2001 John Wiley & Sons, Ltd.
Periapical lesions and dental wear in the early Maori
Authors: Kieser J.A. , Kelsen A. , Love R. , Herbison P.G.P. , Dennison K.J.
Published: January 2005

Dental wear and intrabony lesions were evaluated in a sample of 225 skulls (136 male) of pre‐contact New Zealand Maoris. The degree and direction of surface wear was scored according to the method of Molnar (Molnar 1971. Human tooth wear, tooth function and cultural variability. American Journal of Physical Anthropology34: 175–190) and revealed severe surface loss in both males and females with horizontal wear being the dominant pattern (62.4% male, 57.5% female). The width of coronal tissue above the pulp chamber, as well as the maximum depth and width of periapical lesions, was measured from both standard radiographs and digital images. The high prevalence of periapical pathology in the Maori underlined the extreme nature of dental wear in these people. It is postulated that this degree of tooth loss may be attributable to a change in diet from large birds to marine‐dependence, the introduction of the kumara to New Zealand, dental erosion and finally, to the excessive masticatory forces exerted by a robust facial complex on normally sized teeth. Fenestrated lesions were highly prevalent (83% of skulls) and were centered mostly on the maxilla, with an even distribution among tooth classes. The finding of periapical lesions in teeth with minimal observable wear was attributed to traumatic occlusion. Copyright © 2001 John Wiley & Sons, Ltd.
Neolithic seal exploitation on the Åland Islands in the Baltic Sea on the basis of epiphyseal fusion data and metric studies
Authors: Storå Jan
Published: January 2005

The exploitation of marine resources was of central importance in the subsistence economy on the Åland Islands during the Stone Age. In this study four faunal assemblages from archaeological sites which date to approximately 3300–1800 cal BC are discussed. On all sites seals clearly dominate the mammal fauna with the harp seal (Phoca groenlandica) as the most common species followed by the ringed seal (Phoca hispida). Epiphyseal fusion data and metric comparisons are used to reconstruct the strategies humans used to exploit seals. The results show that the main prey were yearlings and adults and that seasonal hunting strategies were implemented. Ringed seal was hunted on the breeding grounds in late winter. Harp seal was hunted during a longer period of the year, from late spring until early winter. Differences in the hunting strategies directed toward the two species appear to be related to behavioral patterns of the seals. Copyright © 2002 John Wiley & Sons, Ltd.
Environmental effects of tourism industry investments: an inter‐temporal trade‐off
Authors: Kort Peter M. , Greiner Alfred , Feichtinger Gustav , Haunschmied Josef L. , Novak Andreas , Hartl Richard F.
Published: January 2005

Efficient investment programmes in touristic infrastructure have to take into consideration that any kind of tourism reduces the environmental quality. Since pollution shows negative repercussions as concerns the attractiveness of a touristic region, tourism planners have to determine a trade‐off between adequate services for tourists and a clean environment. To deal with this problem in a dynamic context, a three‐state optimal control model is formulated. It turns out that, even if pollution reduction is not a goal in itself, the profit‐maximizing tourism industry should care for ecological conservation. The paper further shows that persistent periodic investment policies are optimal for realistic parameter sets, and provides an economic intuition for such behaviour. From an economic point of view, this result implies that expansionary periods with high investment are followed by periods of stagnation with low investment. Copyright © 2002 John Wiley & Sons, Ltd.
Trajectory optimization involving sloshing media
Authors: Leonpacher Harald , Douglas Steven S. , Woolley Neil H. , Kraft Dieter
Published: January 2005

This paper is concerned with the optimization of the transport motion of an open topped fluid filled container within a warehouse environment. In particular, optimal trajectories of the motion of the driver–container system in two‐dimensional space will be investigated via numerical solutions of the model equations using sequential quadratic programming. The fluid and the mechanical facility that moves the container are subject to several constraints. The objective of the optimization is the time to transport the container from an initial position to its final destination within the warehouse. Optimization criteria are investigated to control the movement of the fluid within the container. The systems of ordinary and partial differential equations, representing the dynamics of the models are solved numerically using a direct shooting method. The resulting non‐linear programming problem is solved using sequential quadratic programming (SQP). Copyright © 2002 John Wiley & Sons, Ltd.
Faith organizations and neighbourhood councils in Los Angeles
Authors: Musso Juliet Ann , Kitsuse Alicia , Cooper Terry L.
Published: January 2005

Following reforms to the city charter in 1999, the City of Los Angeles is currently implementing a city‐wide system of neighbourhood councils that is intended to increase citizen participation in local governance and make city agencies more responsive to local needs. As neighbourhood council formation has gotten underway, faith organizations (FOs) have been identified as a promising resource for mobilizing involvement among groups that are traditionally underrepresented in the governance process. This article discusses the potential value of FOs' involvement in neighbourhood councils, as well as the likely obstacles to their participation, and reports preliminary findings from ongoing field research on neighbourhood council formation in Los Angeles. Given the diversity of religious missions and attitudes toward political involvement among American faith institutions we find it difficult to generalize about the likely role of the faith community in neighbourhood councils. However, the historical focus of Christian churches on issues of social justice as opposed to local community action, as well as the relative lack of participation by FOs in neighbourhood council formation to date, suggests that widespread involvement of FOs in the neighbourhood council process may be difficult to achieve. A targeted strategy of outreach and organizing directed toward those FOs most likely to participate seems required. Copyright © 2002 John Wiley & Sons, Ltd.
Preparation of polyaniline‐sulfate salt ­by emulsion and aqueous ­polymerization pathway without using ­protonic acid
Authors: Palaniappan S.
Published: January 2005

Aniline was polymerized directly into polyaniline‐sulfate salt without using protonic acid in this work. Polyaniline‐sulfate salt was prepared by emulsion and aqueous polymerization pathways. The dopant i.e. sulfate ion in polyaniline‐sulfate salt was generated from ammonium persulfate which was used for oxidizing aniline. Ammonium persulfate acts both as oxidizing agent as well as protonating agent in the polymerization process of aniline to polyaniline salt. The efficiency of oxidizing and protonating power of ammonium persulfate is increased by the use of surfactant. The activity of ammonium persulfate is further increased by the use of sulfuric acid as protonic acid. It may be necessary to consider the effect of sulfate ion which is generated during the oxidation process of aniline in the chemical polymerization of aniline to polyaniline salt by ammonium persulfate either aqueous or emulsion polymerization pathway in the presence of protonic acid/functionalized protonic acid. Copyright © 2001 John Wiley & Sons, Ltd.
Catalytic behaviors of silica‐supported methylcellulose‐L‐phenyl alanine–platinum complexes in asymmetric hydrogenation of diacetone alcohol
Authors: Huang Kai , Xue Lei , Huang Mei‐Yu , Jiang Ying‐Yan
Published: January 2005

A new chiral natural bio‐polymer–metal complexe, silica‐supported methylcellulose‐L‐phenyl alanine–platinum complex (SiO
2‐MC‐L‐Phe–Pt) has been prepared by a very simple method, and the Pt complex has been found to be able to catalyze the asymmetric hydrogenation of diacetone alcohol to give (R)‐(−)‐2‐methyl‐2,4‐pentandiol at room temperature and under atmospheric hydrogen pressure. The product and optical yields of 2‐methyl‐2,4‐pentandiol amounted to 67.0 and 92.7%, respectively. The product and optical yields were remarkably affected by the Pt content in the complex, the kind of solvent and the reaction temperature. This catalyst was very stable and could be reused several times without any remarkable change in optical catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and characterization of a series of novel hyperbranched conjugated polymers
Authors: He Qingguo , Lin Tong , Yang Junlin , Lin Hongzhen , Bai Fenglian
Published: January 2005

A series of novel hyperbranched conjugated luminescent polymers with different length of alkyloxy substitution were designed, synthesized, and characterized by FT‐IR, 1H‐NMR, 13C‐NMR and gel permeation chromatography (GPC). Their special photophysical properties can be attributed to their hollowed and twisted structure. Their electrochemical and electroluminescent properties were investigated. The maximum quantum efficiency of light emitting device (LED) made from C1‐HPV is 0.02% at 15 V. Copyright © 2002 John Wiley & Sons, Ltd.
Polymerization of γ‐stearylL‐glutamateN‐carboxyanhydride with multifunctional porphyrin initiator
Authors: Wu Jian , Hu Xiao‐Ping
Published: January 2005

Ring‐opening polymerization of γ‐stearylL‐glutamateN‐carboxyanhydride (SLGNCA) was performed with a multifunctional porphyrin initiator, meso‐tetrakis(4‐aminophenyl) porphyrin (TAPP), to produce a novel porphyrin‐containing polypeptide. It was found that the yield and intrinsic viscosity of the obtained polymer (PSLG/TAPP) was mainly effected by the initial ratio of SLGNCA to TAPP. The polypeptide was extensively characterized by visible absorption spectroscopy, gel permeation chromatography (GPC),1H‐NMR and IR techniques. It was clarified that the polypeptide has a four‐arm branched structure with a porphyrin core. Copyright © 2002 John Wiley & Sons, Ltd.
Poly(ethylene‐block‐vinylalcohol) film with amphiphilic surface at high temperature
Authors: Shimamura Kaoru , Munesawa Yuhji , Uchida Tetsuya , Hikasa Nobuhiko
Published: January 2005

Poly(ethylene‐block‐vinylalcohol) (PE/PVA), which consisted of both hydrophobic and hydrophilic blocks, was prepared by using polyethylene single crystals as starting material. Polyethylene single crystals were reacted with fuming nitric acid resulting in long methylene chains with functional groups such as COOH and NO2 at the ends (the chain lengths were almost the same as the lamellar thickness of polyethylene single crystal). The functionalized methylene chains were allowed to react with 4‐aminostyrene to give corresponding amides, i.e. methylene chains with vinyl groups at the ends (macromer). The macromers were extended by block‐copolymerization with vinyl acetate, then saponified resulting in PE/PVA block copolymer.

The block copolymer was molded into sheets which were subsequently heat‐treated in contact with hydrophilic or hydrophobic media. Depending on the media, the sheet surface changed at high temperature reversibly from hydrophilic to hydrophobic and vice versa. The surface property was fixed by quenching because both blocks were able to crystallize. Thus the surface of ­this material can be tailored for various purposes at ­high temperature, and then used in stable condition at room temperature. Copyright © 2002 John Wiley & Sons, Ltd.
Catalytic behavior of silica‐supported methylcellulose–oxalic acid–Pt complex in asymmetric hydrogenation of 2‐butanone and itaconic acid
Authors: Liu Hong‐Wen , Xin Fei , Wu Li‐Min , Huang Mei‐Yu , Jiang Ying‐Yan
Published: January 2005

A new silica‐supported biopolymer–oxalic acid–Pt complex was prepared by a simple method. Methylcellulose (mc) reacted with oxalic acid in the presence of silica to give a complex SiO2–MC–(COOH)2 on the surface of silica, then reacted with H2PtCl6·6H2O to form a Pt complex [SiO2–MC–(COOH)2–Pt]. This complex was found to be able to catalyze the asymmetric hydrogenation of 2‐butanone to (S)‐(+)‐2‐butanol and itaconic acid to (S)‐(−)‐methylsuccinic acid, respectively, at room temperature and under 1 atm H2. The experimental results showed that the product and optical yields were remarkably affected by the Pt content in the complex and the catalyst could be reused without any remarkable change in optical catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
Asymmetric epoxidation of cinnamyl alcohol catalyzed by silica‐supported casein–Co complex
Authors: Zhang Xi , Han Bing , Hua Yu‐Ning , Huang Mei‐Yu , Jiang Ying‐Yan
Published: January 2005

Silica‐supported casein–Co complex (Si‐CA–Co) was prepared from silica, casein and cobalt chloride, and found to be useful as a chiral catalyst for the asymmetric epoxidation of cinnamyl alcohol to (2R,3R)‐(+)‐3‐phenylglycidol at 70 °C and under 1 atmospheric oxygen pressure. When a proper content of cobalt in the Si‐CA–Co complex and suitable reaction conditions were selected, the product and optical yield could be amounted to 70.6 and 92.0%, respectively, and the Si‐CA–Co complex could be reused several times without any remarkable change in the optical catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
Fabrication and biocompatibility of cell scaffolds of poly(L‐lactic acid) and poly(L‐lactic‐co‐glycolic acid)
Authors: Shi Guixin , Cai Qing , Wang Changyong , Lu Ning , Wang Shenguo , Bei Jianzhong
Published: January 2005

In this paper, poly(L‐lactic acid) (PLLA) and poly(L‐lactic‐co‐glycolic acid) (PLGA) were synthesized, and the biocompatibility of PLGA(50/50) (molar ratio) was evaluated by observing the tissue response during implanting PLGA(50/50) into rats. After the PLGA(50/50) was implanted into rats for 12 weeks, the lymphocytes and plasma cells became small or disappeared at the muscle tissue of implant site which indicates the biocompatibility of PLGA(50/50) is very good. A series of porous cell scaffolds of PLGA and PLLA were prepared by using a solution‐casting/salt‐leaching technique. An improved method in which a density bottle instead of a graduated cylinder was developed to measure their porosities. It was found that the accuracy and reproducibility of the improved method for measuring porosity are excellent. A porous PLGA(50/50) scaffold was used to study chondrocytes culture. The chondrocytes were proliferated in porous PLGA(50/50) scaffold and the composite cell/PLGA was successfully obtained for cartilage regeneration. Copyright © 2002 John Wiley & Sons, Ltd.
Dependence of morphology on composition of poly(L‐lactide)– poly(ethylene glycol) multiblock copolymers
Authors: Luo Weijun , Li Suming , Bei Jianzhong , Wang Shenguo
Published: January 2005

Poly(L‐lactide)–poly(ethylene glycol) (PLA–PEG) multiblock copolymers with predetermined short blocks (Mn ≤ 3000) were synthesized by polyesterification of PLA diols with PEG diacids in the presence of dicyclohexycarbodiimide and dimethylamide pyridine. The molecular structure and morphological features of the resulting copolymers were characterized by analytical techniques, such as gel permeation chromatography (GPC), viscometry,
1H‐NMR, differential scanning calorimetry (DSC), X‐ray diffractometry. The dependence of the morphology on the molecular structure was analyzed in detail. The results indicated that these copolymers were markly improved in practical properties, such as miscibility between the two components, non‐crystallinity. And the regular variation in these respects suggests that the properties of the copolymers can be modulated by adjusting the block length of the two components. Copyright © 2002 John Wiley & Sons, Ltd.
Preparation of temperature‐sensitive polymer films by surface photografting techniques
Authors: Li Bin , Chen Wenguang , Liu Xiaohua , Wang Xiaogong , Zhou Qixiang
Published: January 2005

In this paper, poly(N‐isopropylacrylamide) has been successfully grafted on polypropylene (PP) films by pre‐dipping photografting and dormant radical photografting techniques. It was found that higher grafting yield was achieved by the dormant radical photografting method. An optimum concentration of N‐isopropylacrylamide monomer existed both for the pre‐dipping photografting and for the dormant radical photografting methods. The grafting yield was improved by increasing the UV irradiation time for both methods. Water absorbency of grafted PP films prepared by the two methods was similar and increased nearly linearly with the improvement of grafting yield. At constant temperature and humidity, the grafted PP films lost the absorbed water continually before the water absorbency reached an equilibrium value at this temperature. Copyright © 2002 John Wiley & Sons, Ltd.
A novel polyurethane‐modified poly(N‐isopropylacrylamide) hydrogels
Authors: Liu Xiaohua , Tang Liming , Dai Yu , Wang Xiaogong , Liu Deshan
Published: January 2005

Two kinds of vinylic‐capped urethane acrylate anionomer (UAA) prepolymers were prepared in two steps. pH sensitive hydrogels were synthesized by free radical polymerization of UAA. A series of pH and temperature sensitive hydrogels were prepared by copolymerization of N‐isopropylacrylamide (NIPA) and UAA at various ratios. The influences of pH and temperature on the swelling ratios (SRs) of these hydrogels were investigated in detail. The results indicated that the incorporation of PUAA into the composite hydrogels had little effect on the lower critical solution temperature (LCST) of poly‐(N‐isopropylacrylamide) (PNIPA). The swelling ratios strongly depended on both the composition of the hydrogels and the polymerization temperature. Copyright © 2002 John Wiley & Sons, Ltd.
Reactive‐HALS I: Synthesis, characterization, copolymerization reactivity and photo‐stabilizing performance applied in UV‐curable coatings
Authors: Liu Xiaoxuan , Yang Jianwen , Chen Yonglie
Published: January 2005

The synthesis and characterization of four monomeric hindered piperidinol derivatives, 4‐methacryloyl‐1,2,2,6,6‐pentamethyl‐piperidinyl (MPMP), 4‐acryloyl‐1,2,2,6,6‐pentamethyl‐piperidinyl (APMP), 4‐methacryloyl‐2,2,6,6‐tetramethyl‐piperidinyl (MTMP) and 4‐acryloyl‐2,2,6,6‐tetramethyl‐piperidinyl (ATMP) as reactive‐hindered amine light stabilizers (r‐HALS) were reported. Their structures and compositions have been characterized by FT‐IR,1H‐NMR, GC/MS and elemental analysis. The aim of the present work is to examine the copolymerization reactivity of r‐HALS, and to investigate the photostabilizing performance applied in UV‐curable coatings. The results have shown that r‐HALS (MPMP, APMP, MTMP and ATMP) can be readily copolymerized with commonly used oligomer or reactive diluent. The photostabilizing effect of these r‐HALS applied in UV‐curable coatings of an epoxy acrylate (CN124A80) was better than that of commercial HALS (Tinuvin 770 and Tinuvin 292). Copyright © 2002 John Wiley & Sons, Ltd.
Inorganic–organic hybrid materials­from poly(methylmethacrylate) ­crosslinked by an organically modified ­oxozirconium cluster. Synthesis and ­characterization
Authors: Gross Silvia , Trimmel Gregor , Schubert Ulrich , Noto Vito Di
Published: January 2005

The presence of inorganic moieties in polymers greatly expands the range of their properties and applications and at the same time overcomes some of the disadvantages of conventional polymer chemistry, such as low temperature hardness and brittleness, photochemical instability, or low electric conductivity. In this framework, the cluster Zr4O2(OMc)12 (OMc = methacrylate) (Zr4), was prepared starting from zirconium butoxide and an excess of methacrylic acid. Inorganic–organic hybrid materials were then synthesized by radical‐initiated copolymerization of Zr4 and methylmethacrylate in benzene with different molar ratios. Glassy, highly transparent hybrid polymers were obtained. The thermal behavior, the composition and the structure of the polymers were investigated by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy (IR), 13C MAS NMR, X‐ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectrometry (ICP‐AES). The spectroscopic data show that­the clusters crosslink the poly(methylmethacrylate) (PMMA) chains and that the oxometallate complexes are completely incorporated into the hybrid materials. Compared with the undoped polymer, the hybrid polymers have enhanced thermal properties and a characteristic dielectric behavior. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of functional groups on the ­thermal degradation of copolymers
Authors: Shibasaki Yoshio , Yang Min , Sun Ling
Published: January 2005

Thermal degradation mechanisms of the copolymers of styrene (St) with methacrylonitrile (MAN) and α‐methylstyrene (αMSt) were studied by pyrolysis gas chromatography (Py‐GC) and thermogravimetry (TG). Thermal degradation of vinyl polymers in flash pyrolysis proceeded mainly in the competition between depolymerization and back biting reaction caused by abstraction of H atom at α‐position in pen‐penultimate unit. Monomer molecules were regenerated by depolymerization, and dimer, trimer and ologomers were produced by back biting reaction. Methyl groups at α‐position of monomer unit strictly hindered the back biting reaction. The role of functional groups on the thermal degradation was elucidated on the basis of bond dissociation energies­of main chain (QCC), apparent activation energies­(ΔEa) obtained by Ozawa's method from the TG­curves at various heating rates. Effect of chemical reactivity of C≡N group in MAN unit on the thermal degradation was clarified by the controlled rate thermogravimetry (CRTG). Copyright © 2002 John Wiley & Sons, Ltd.
Organometallic polymers: synthesis and electro‐optical properties
Authors: Fratoddi Ilaria , Altamura Patrizia , Sterzo Claudio Lo , Furlani Anita , Galassi Emiliano , D'Amico Arnaldo , Russo Maria V.
Published: January 2005

The synthesis of organometallic polymers, namely ­Pt‐DOB ([Pt(PPh3)2(CCp C6H4(2,5OC16H33)2CC)]
n and Pt‐TRI ([Pt(PBu
3)
2(CCC
4H
2SCCC
4H
2SCCC
4H
2SCC)]
n) has been carried out. The platinum polyynes with a rigid rod structure have been obtained by two synthetic routes: dehydrohalogenation and Stille coupling in the version “extended one pot” (EOP). Pt‐DOB and Pt‐TRI have been fully characterized by means of FT‐IR, UV‐vis,
1H‐ and
31P‐NMR, gel permeation chromatography (GPC) and photoluminescence spectra. Different organic spacers have been employed in order to study and compare the response of new materials as mass sensors, using a quartz crystal microbalance sensor (QCMB) technique. The materials were exposed to ethanol and isopropanol vapors and showed a different response depending on the nature of the organic spacer. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of branched polymers by means of living anionic polymerization — Part 6. Synthesis of well‐defined comb‐like branched polystyrenes and graft copolymers with highly branched architecture
Authors: Hirao Akira , Kawano Hiroki , Ryu Sang Woog
Published: January 2005

The synthesis of well‐defined comb‐like branched polymers and graft copolymers with one branch chain per repeating unit by the methodology based on “grafting‐onto” method is described. The methodology involves three reaction steps. The first reaction step is to prepare poly(m‐tert‐butyldimethylsilyloxymethylstyrene)s with predictable molecular weights and narrow molecular weight distributions by living anionic polymerization of m‐tert‐butyldimethylsilyloxymethylstyrene in tetrahydrofuran (THF) at −78 °C. In the second reaction step, the resulting polymers are quantitatively transformed into poly(m‐chloromethylstyrene)s by treatment with BCl
3. Finally, by the reaction of the poly(m‐chloromethylstyrene)s thus prepared with living anionic polymers of styrene, isoprene, and 2‐vinylpyridine, comb‐like branched polymers and graft copolymers are synthesized. Each of all linking reactions proceeded quantitatively to afford the branched polymers with one branch chain per repeating unit. Attempts to synthesize highly branched polystyrenes having more than one branch chain per repeating unit were made by reacting poly(m‐bromomethylstyrene)s with the polymer anions prepared from polystyryllithium with end‐functionalized polystyrenes with 1,1‐diphenylethylene moiety. For the same purpose, we prepared a new polystyrene derivative having two bromomethylphenyl groups in each styrene unit to react with polystyryllithium. Copyright © 2002 John Wiley & Sons, Ltd.
On the study of polyurethane Ionomer—Part I
Authors: Chwang C. P. , Wang C. L. , Kuo Y. M. , Lee S. N. , Chao A. , Chao D. Y.
Published: January 2005

The reaction of toluene diisocyanate (TDI) with dimethylol propionic acid (DMPA) or diaminopentane sulphonic acid sodium salt (ES‐200) and other additives to form the structure of anionic polyurethane (PU) ionomer molecule has been proven by FT‐IR spectroscopy.

In aqueous solution, the surface tension of anionic PU ionomer molecule is seen to slightly increase with increasing concentration of ES‐200. This is because the adsorption of hydrophobic groups of ionomer molecules at the surface of aqueous solution becomes even more ordered. Under the same experimental conditions, the surface tension of anionic PU ionomer molecule appears to slightly decrease with increasing concentration of DMPA, as a result of increased hydrophobic groups of ionomer molecule adsorbed at the surface of aqueous solution. The number average particle size of anionic PU ionomer molecule in aqueous solution appears to steadily increase with an increase in the concentration of DMPA or ES‐200. This is because the intermolecular interaction between ionomer–ionomer molecules themselves and between ionomer–water molecules may increase the free volume of anionic PU ionomer molecule, thus causing their number average particle size to increase.

Experimental results indicate that both the tensile strength and the modulus of self‐cured film of anionic PU ionomer molecule appear to decrease with increasing concentration of DMPA or ES‐200, as a result of intramolecular interaction. However, the elongation of self‐cured film of anionic PU ionomer molecule is seen to increase with increasing concentration of DMPA or ES‐200. This may be the result of weakening crosslinking due to strong intramolecular interaction of ionomer molecule. For the peel strength of self‐cured film of anionic PU ionomer coated on the fabric (30% polyester/70% cotton), it has been found that the peel strength increases with increasing concentration of DMPA or ES‐200, as a result of increased hydrophilic interaction between ionomer molecules themselves. Copyright © 2002 John Wiley & Sons, Ltd.
On the study of polyurethane ionomer — Part II
Authors: Chwang C. P. , Lee S. N. , Kuo Y. M. , Chao S. , Chao D. Y.
Published: January 2005

Photosensitive‐fluorescein polyurethane (PU) ionomer was successfully synthesized at our laboratory. The reaction of toluene diisocyanate with polyester, fluorescein, hydroxypropyl acrylate and other major additives to form the structures of these ionomers has been proven by FT‐IR spectroscopy. For a dilute concentration of photosensitive‐fluorescein PU ionomer molecule in aqueous solution, the fluorescence studied exhibits fluorescence at around 508 nm. In aqueous solution, the number average particle size appears to increase with increasing concentration of epoxy, fluorescein and hydroxypropyl acrylate used to prepare the photosensitive‐fluorescein PU ionomer molecules. The reason for the free volume of photosensitive‐fluorescein PU ionomer molecules is due to strong intermolecular interactions between hydrophilic groups of these ionomer molecules increasing. Therefore, the number average particle sizes of these ionomer molecules increases. Furthermore, the addition of benzoin as a photoinitiator to photosensitive‐fluorescein PU ionomer molecule results in an increase is the average particle size of this ionomer molecule. This is due to increased free volume resulting from strong intermolecular interaction between hydrophilic groups of ionomer molecules. For self‐cured films made by photosensitive‐fluorescein PU ionomer, the tensile strength is seen to increase with increasing concentration of epoxy, fluorescein and hydroxypropyl acrylate, respectively. This may be attributed to increased crosslinking due to strong intermolecular interaction between photosensitive‐fluorescein PU ionomer molecules themselves. However, the addition of benzoin as a photoinitiator to photosensitive‐fluorescein PU ionomers results in an increase in the tensile strength of these ionomers as well. Copyright © 2002 John Wiley & Sons, Ltd.
Preparation of benzyl alcohol by hydrogenation of benzoic acid catalyzed by a magnesium Oxide‐supported poly‐γ‐aminopropylsiloxane–Ru–Pd–Sn complex
Authors: Mao Bao‐Wei , Wu Jin‐Fei , Huang Mei‐Yu , Jiang Ying‐Yan
Published: January 2005

Benzyl alcohol in higher than 90% yield was achieved from the hydrogenation of benzoic acid catalyzed by using a magnesium oxide‐supported poly‐γ‐aminopropylsiloxane–ruthenium–palladium–stannum trimetallic complex catalyst (MgO–NH2–Ru–Pd–Sn) in 1,4‐dioxane. The Ru/Pd/Sn mole ratio, reaction temperature, hydrogen gas pressure and reaction time greatly influenced the reaction. The catalyst was stable and could be used repeatedly without any remarkable changes in catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
Asymmetric hydration of allyl alcohol catalyzed by polysulfostyrene– gelatin–Co complex
Authors: Zhang Xi , Li Yan‐Jie , Huang Mei‐Yu , Jiang Ying‐Yan
Published: January 2005

A new chiral polymer–metal complex, polysulfostyrene–gelatin–cobalt complex (PSS–GE–Co) has been prepared and found to be able to catalyze the asymmetric hydration of allyl alcohol to give (S)‐(−)‐1,2‐propanediol in 98% yield with 98.9% optical yield. The catalyst is very stable and can be reused without any remarkable effect in catalytic activity and optical selectivity. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and characterization of liquid crystalline copolyesters containing horizontal and lateral rods in main chain
Authors: Li Chenguang , Xie Xuming , Cao Shaokui
Published: January 2005

A series of liquid crystalline copolyesters containing both horizontal and lateral rods in main chain were synthesized through solution polymerization of 2,5‐bis(4‐alkoxy benzoyloxy)hydroquinone, 4,4′‐dihydroxy‐α,ω‐diphenoxydecane and 4,4′‐dichloroformyl‐α,ω‐diphenoxydecane. These copolyesters were soluble in common organic solvents, showed thermotropic nematic liquid crystallinity that can be easily obtained at room temperature, thereby making them processable at relatively low temperatures in their high‐ordered liquid crystalline states where they are thermally stable. Their thermal transitions can be well adjusted by judiciously controlling the attachment content of lateral rods, and their thermal behaviors were well examined. All synthesized polymers were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide angle X‐ray diffraction (WAXD). Copyright © 2002 John Wiley & Sons, Ltd.
Preparation and catalytic behaviors of silica‐supported casein–Fe complex in hydrogenation of cyclohexanone
Authors: Shen Lin , Ye Jiang‐Li , Huang Mei‐Yu , Jiang Ying‐Yan
Published: January 2005

A silica‐supported casein–Fe complex (SiO
2‐CA‐Fe
III) has been prepared and used as catalysts for the hydrogenation of various organic compounds under mild conditions, especially to catalyze the hydrogenation of cyclohexanone to cyclohexanol effectively at room temperature and 1 atmH
2. The experimental results indicate that Fe content in SiO
2‐CA‐Fe complex, reaction temperature and time greatly influence the yield of cyclohexanol. When proper reaction conditions were selected, the yield of cyclohexanol could amount to 100%. This complex was very stable and could be reused without any change in catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
A rapid TLC bioautographic method for the detection of acetylcholinesterase and butyrylcholinesterase inhibitors in plants
Authors: Marston A. , Kissling J. , Hostettmann K.
Published: January 2005

A simple and rapid bioautographic enzyme assay on TLC plates has been developed for the screening of acetylcholinesterase and butyrylcholinesterase inhibition by plant extracts. Enzyme activity was detected by the conversion of naphthyl acetate into naphthol and the formation of the corresponding purple‐coloured diazonium dye with Fast Blue B salt. Inhibitors of cholinesterases produced white spots on the dye‐coloured background of the TLC plates. The alkaloids galanthamine and physostigmine, which are known inhibitors of acetylcholinesterase, were used to determine the sensitivity of the assay. Various plant extracts were tested using the bioassay. Copyright © 2001 John Wiley & Sons, Ltd.
Congenital lymphedema presenting with increased nuchal translucency at 13 weeks of gestation
Authors: Souka A. P. , Krampl E. , Geerts L. , Nicolaides K. H.
Published: January 2005

Congenital lymphedema is an autosomal dominant condition characterized by chronic tissue swelling caused by deficient lymphatic drainage due to hypoplastic/aplastic lymphatic vessels and usually affecting the lower limbs. The locus of the gene has been identified in the long arm of chromosome 15. We report one case of congenital lymphedema presenting with increased nuchal translucency at 13 weeks of gestation. Copyright © 2002 John Wiley & Sons, Ltd.