bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpretations in Islamic Political Thought
Authors: Al-Saud Laith
Published: August 2005

This paper offers an analysis of many of the presuppositions in interpretations of Islamic political thought. After an initial investigation of some general issues several methodological alternatives will be offered. First and foremost, a general methodology borrowed by Quentin Skinner regarding ‘intentions’ will be employed for our purposes here. Secondly, to supplement Skinner's methods, a method of preliminary questions is offered by which to address Muslim theorists' bodies of works and compel comparative theorists to be more grounded in the overall logic of a particular theorist's worldview.
Sustainability and the urban design process
Authors: Boyko C. T. , Cooper R. , Davey C.
Published: August 2005

The urban design process must be transformed and improved if various stakeholders wish to create sustainable urban environments. Although the UK Government and other influential bodies have written many reports recently about the intimate relationship between urban design and sustainability, much more needs to be done to demonstrate how, when and where sustainability is embedded in the urban design process. There is also a need to understand who the decision makers are within this process and what influences their decisions. A clear picture of how the urban design decision-making process works from start to finish, and how sustainability is embedded within this process, can help to achieve the goals and objectives of urban sustainability in the 24-hour city. This paper begins by defining urban design and describing the urban design process, highlighting the major stages and the general tasks involved at each stage. Sustainability and urban sustainable development are briefly discussed next. The final section indicates, through case study research comprising the VivaCity2020 project, where sustainability may be embedded within the urban design process.
Decision-support tools: moving beyond a technical orientation
Authors: Sahota P. S. , Jeffrey P.
Published: August 2005

The very nature of decision making has been changed by the contemporary emphasis on sustainability. Organisations wishing to address the sustainability agenda must include a complex and complicated set of social, environmental and economic considerations in their deliberations. This paper begins with a literature review that describes the drivers for, and barriers to, the adoption of decision-support tools (DSTs). The design and execution of a scoping study focused on identifying and characterising such drivers and barriers are then reported. Findings suggest that the decision-making context is central to the adoption of DSTs and that organisations and their decision support systems (DSSs) need to embrace procedures that can deal with complexity and go beyond the technical orientation of previous tools.
Decision-support tools for sustainable urban development
Authors: Kapelan Z. , Savic D. A. , Walters G. A.
Published: August 2005

The focus of this paper is on the complex, integrated decision-support tools (DSTs) for sustainable urban development. The main goal is to identify the principal strengths and weaknesses of these tools while considering the broader issue of how an integrated urban decisionsupport system can be developed (or existing tools improved) that will integrate a wide range of criteria including socio-economic and environmental aspects, plus stakeholder participation, into the decision-making process. To achieve this goal, a relatively large number of various DSTs were first identified. These tools were then analysed using a set of criteria developed specifically for that purpose. For each criterion, a description of a perceived ideal DST is provided and then used when analysing existing DSTs. Finally, it is concluded that modern integrated DSTs for sustainable urban development, despite increased complexity and flexibility, still need to be improved to provide better support in the associated decision-making processes. The recommended areas for future improvements include higher levels of DST integration, introduction of the systematic risk and uncertainty modelling, wider use of the ranking and optimisation methodologies, further development of the detailed impact assessment models, wider and better use of advanced visualisation techniques, improved support for group decision making and communication and more systematic calibration and validation of the models.
Modelling sustainable urban water management options
Authors: Sakellari I. , Makropoulos C. , Butler D. , Memon F. A.
Published: August 2005

This paper describes the development of a prototype decision-support tool, termed optioneering tool-1 (WaND-OT1), supporting decisions for urban water management, which explores issues of the compatibility of alternative sustainable technologies and sustainability evaluation at a strategic level. TheWaND-OT1 prototype was developed in Excel and Matlab (SIMULINK) to be both computationally strong and user-friendly. The user interacts with the WaND-OT1 through the Excel platform, which exchanges data and user preferences with a SIMULINK-based systems model. To explore its potential and identify research directions, the prototype WaND-OT1 was tested under a variety of urban water management scenarios, including water recycling, rainwater harvesting and introduction of low water consumption devices. It is concluded that even at this early stage of its development, the WaND-OT1 can be considered as a flexible tool that successfully represents the main components of the urban water cycle and produces plausible and useful results in terms of the interaction of components.
Economic assessment tool for greywater recycling systems
Authors: Memon F. A. , Butler D. , Han W. , Liu S. , Makropoulos C. , Avery L. M. , Pidou M.
Published: August 2005

The implementation of water demand management strategies, particularly in urban environments, can contribute towards improved sustainability (or at least reduce unsustainability) in the water sector. Greywater treatment, and its subsequent use for toilet flushing, is one of the demand management options offering considerable water-saving potential. The uptake of greywater recycling systems (GRSs), particularly in the UK, is low. One of the reasons for such a low uptake is the perception that GRSs have a high (unsustainable) cost/benefit ratio. This paper presents progress on the development of a whole-life cost (WLC) model, aimed at facilitating decision making for the implementation of GRSs in relation to their economic viability.
Integrated systems approach to managing urban pollution
Authors: Pettit C. , Azapagic A. , Jefferis S.
Published: August 2005

This paper outlines a new integrated decision-support framework for a more sustainable management of urban pollution, developed within the project ‘Pollutants in the urban environment’ (PUrE). The framework comprises a suite of appropriate models and tools that can be selected by different stakeholders or end-users (such as policy-makers, local authorities, industry, researchers and non-government organisations) to conduct simple screening studies and/or detailed modelling assessments of the effects of pollution in the urban environment. The models and tools enable consideration of individual pollutants and their mixtures released from a wide range of urban sources, as well as evaluation of local and global effects of urban pollution. Examples of the tools and models integrated into the decision-support framework include: life-cycle assessment; substance flow analysis; air and water dispersion and advection modelling; and human health assessment. The important features of the framework are that it is tiered, flexible and modular, allowing the users to choose the appropriate models or tools as well as decision-making paths, depending on their needs and the type of decision-making problem they are addressing. Although the framework is in its early stages of development, its application has already been demonstrated on a number of case studies, as detailed in this paper.
Assessing barriers to sustainable UK urban transport solutions
Authors: Hull A. D. , Tricker R. C.
Published: August 2005

Local authorities in the UK play an active role in ensuring the smooth design and implementation of sustainable transport policy. This paper summarises the findings of a questionnaire survey carried out in 16 local transport authorities, covering the organisational, technical and external challenges faced in the delivery of local transport strategies and schemes. It prioritises the key barriers in the use of decision support tools (i.e. indicators, option generation tools, appraisal techniques, and modelling) and discusses some of the funding challenges which affect the delivery of transport strategies and schemes. The outputs of this research will directly influence the development, practice and use of tools aimed at overcoming these barriers in selected urban transport authorities. This will also strengthen the research evidence base for the implementation of transport policy at a local level in the UK.
The effects of disseminated methane hydrate on the dynamic stiffness and damping of a sand
Authors: Clayton C. R. I. , Priest J. A. , Best A. I.
Published: August 2005

Methane hydrates are ice-like compounds that can exist only under restricted thermobaric conditions, at low temperatures or under high ambient pressure. They are important because of their potential contributions as a future source of energy, to global warming, and as a possible trigger for long run-out submarine slope instability. This paper describes laboratory experiments to synthesise disseminated methane hydrates and to characterise them under small-strain dynamic loading in the resonant column apparatus. The effects of depositing varying quantities of methane hydrate within a sand are investigated by reference to their shear and bulk modulus, and damping, over a range of isotropic effective stress. Results are compared with those obtained on the same sand without hydrate bonding and after dissociation.
A generalised Winkler model for the behaviour of shallow foundations
Authors: Houlsby G. T. , Cassidy M. J. , Einav I.
Published: August 2005

A theoretical model is described for the behaviour of rigid foundations subjected to combined vertical, horizontal and moment loading. The model is based on a generalisation of the Winkler concept of subgrade reaction. Non-linearity of the stress–displacement response is introduced using the concepts of hyperplasticity, and the integration of the stresses over the foundation area is treated within this theoretical framework. The resulting model exhibits (with some limitations) behaviour that quite closely resembles that obtained from experiments and from more sophisticated numerical analyses. The performance of the model is illustrated by calculations for selected load and displacement histories. The primary purpose is to derive models, based on clearly articulated principles, that are capable of describing cyclic behaviour of foundations, and yet retain sufficient simplicity that they can be coupled with analyses of structures. Such models have important applications in the offshore industry for prediction of foundation response under environmental loads.
Soil—pipe interaction due to tunnelling: comparison between Winkler and elastic continuum solutions
Authors: Klar A. , Vorster T. E. B. , Soga K. , Mair R. J.
Published: August 2005

An elastic continuum solution and a Winkler solution of the problem of tunnelling effects on existing pipelines are given. A comparison is made between an elastic continuum solution and a closed-form Winkler solution with Vesic subgrade modulus. Although applying the Vesic expression results in the same moments and displacements under external loading in a Winkler system and the elastic continuum, it is found that its use is not necessarily adequate for the problem of tunnelling effects on pipelines and may not be conservative owing to possible underestimation of bending moments. An alternative expression for the subgrade modulus is provided, resulting in similar maximum bending moments in the Winkler and elastic continuum systems.
Shear strength of cohesionless soils at low stress
Authors: Fannin R. J. , Eliadorani A. , Wilkinson J. M. T.
Published: August 2005

Mobilisation of shear strength in shallow translational slips occurs at very low effective stress. Accordingly, a series of direct shear box tests was performed to characterise the strength of colluvium, under drained conditions, at vertical effective stresses between 5 and 20 kPa. Results from in situ tests on undisturbed block samples of moist soil are compared with laboratory tests on dry reconstituted specimens of the soil matrix only. The in situ tests determine a mean value of peak or maximum angle of shearing resistance between 58° and 64°, and a mean value at large displacement between 46° and 52°, with 46° believed representative of shearing at constant volume. Mobilisation of similar angles of shearing resistance, between 46° and 48°, at large displacement in laboratory tests on the 25 mm minus fraction indicates that the soil matrix is controlling strength. The values at large displacement are attributed to mineralogy, grain shape and angularity, and grain size distribution of the soils. Observations of the angle of repose corroborate the measured values at large displacement. The peak or maximum values are consistent with the phenomenon of stress dilatancy and, although very high, compare well with limited data reported for coarse granular soils at very low effective stress.
Thickness of interfacial transition zone and cement content profiles around aggregates
Authors: Zheng J. J. , Li C. Q. , Zhou X. Z.
Published: August 2005

Interfacial transition zones (ITZ) in concrete constitute the weakest link in the concrete matrix and significantly affect the properties of concrete. To evaluate quantitatively the effect of ITZ on the physical and mechanical behaviour of concrete, it is imperative to characterise the microstructure of ITZ. The intention of this paper is to investigate the characteristics of ITZ microstructure in a statistical manner. In this paper, an algorithm is developed to simulate the distribution of cement particles between aggregates in concrete. After verifying the developed algorithm with experimental data, models for the thickness of ITZ and the cement area density between aggregates are developed as a function of the water-to-cement ratio, maximum cement diameter and the distance from the aggregate surface. It is found that the thickness of ITZ is in a range of 9 to 51 μm for normal concrete. A merit of the developed models is that they are closely related to design parameters of concrete used by practitioners. It is concluded that the thickness of ITZ and cement content profiles around aggregates can effectively explicate the characteristics of ITZ microstructure.
Effect of corrosion on ductility of reinforcing bars
Authors: Du Y. G. , Clark L. A. , Chan A. H. C.
Published: August 2005

An experimental investigation into the effect of corrosion on the ductility of steel reinforcement is reported. Both accelerated and simulated corrosion tests were conducted on bare bars and on bars embedded in concrete. The mechanism and degree of the reduction of ductility of reinforcement due to corrosion were examined. The influence of bar type and diameter on ductility of corroded reinforcement is discussed. The experimental results indicate that, since local attack penetration results in a significant variation of residual cross-section along its length, corrosion significantly reduces ductility of reinforcement. Although the strength ratio, elastic modulus and hardening strain only vary with bar type rather than corrosion level, the elongation, ultimate strain and ductile area of corroded reinforcement reduce much more significantly than do those of their yield and ultimate strengths. There is concern regarding bar ductility since about 10% corrosion may possibly decrease the ultimate strain of reinforcement below the minimum requirement specified in CEB Model Code 90 for class S reinforcement. Even though the elongation, ultimate strength and ductile area parameter of corroded small diameter and/or plain bars reduce more than those of large diameter and/or ribbed ones, such differences are not significant and can be neglected. Finally, a set of simple empirical equations is proposed to assess the ductility of corroded reinforcement in practice.
Shake table testing of tubular steel bracing members
Authors: Elghazouli A. Y. , Broderick B. M. , Goggins J. , Mouzakis H. , Carydis P. , Bouwkamp J. , Plumier A.
Published: August 2005

An experimental study on the seismic response of cold-formed steel tubular members functioning as bracing members in concentrically braced frames is described. A number of shake table tests were carried out to examine member and storey performance under earthquake loads. Three different square and rectangular hollow cross-sections were utilised for the bracing members. It is shown that maximum brace tensile forces can be over 30% higher than those estimated using the actual yield strength, due to strain hardening and strain rate effects. Moreover, the experimental storey shear can exceed that predicted by design procedures by more than 50%. The tests also indicate that the ductility demand under seismic loading can be estimated reasonably well for the frame models using a conventional equal-energy idealisation. In addition, the results illustrate generally satisfactory performance for braces with member slenderness exceeding typical limits in seismic codes.
Eurocodes: using reliability analysis to combine action effects
Authors: Gulvanessian H. , Holicky M.
Published: August 2005

The head structural Eurocode for the design of buildings and other civil engineering works, EN 1990 Basis of Structural Design, establishes for all the Eurocodes the principles and requirements for safety, serviceability and durability. It provides alternative design procedures, for which national choice is allowed, in particular for the three fundamental combinations of action effects for the persistent and transient design situations in the verification of ultimate limit states. An example of a generic structural element shows that the alternative combinations may lead to considerably different reliability levels depending upon the ratio of variable actions to the total load. Probabilistic methods of structural reliability theory are used to identify characteristic features of each combination and to formulate general recommendations for the BSI National Annex for EN 1990.
Enhancing ductility of reinforced concrete frame buildings
Authors: Kuang J. S. , Atanda A. I.
Published: August 2005

Two large-scale, two-storey subframes with non-seismic reinforcement detailing and limited seismic detailing were tested under quasi-static cyclic loading to investigate the seismic behaviour and ductility enhancement of reinforced concrete frame buildings for low-to-medium earthquakes. The inherent ductility of an ordinary moment-resisting reinforced concrete frame was experimentally established by testing the subframe specimen in the case where the reinforcement detailing is consistent with that typically adopted for frame buildings in which the design code has not stipulated any requirement for seismic compliance in the steel details. Experimental investigation was then performed on the other subframe specimen to investigate the enhancement to ductile response behaviour following modifications of the reinforcement detailing technique. The modifications were simple and included reducing the spacing between the stirrups while maintaining the ratio of the stirrup area to spacing; the provision of double-U stirrups at the beam–column joint and the addition of inclined bars within the beam at the support region. It is concluded that ordinary moment-resisting frame buildings might not withstand low-to-moderate seismic events. However, the ductility of frame buildings can be significantly improved with minor modification in reinforcement detailing specifications, which do not result in radical changes in currently practiced design and detailing techniques and a significant increase in construction cost.
Designing thin-walled composite-filled beams
Authors: Anwar Hossain K. M.
Published: August 2005

Thin-walled composite-filled beams consist of a cold-formed open steel box section with an infill of concrete. The strength of such beams is limited by the compression buckling capacity of the steel plate at the top of the open box section. Enhancement of strength is possible by stiffening the compression steel plates at the open end of the box section with various modes of interface connections or strength-enhancement devices. In this paper, the effect of various strength-enhancement devices is correlated to the generation of shear bond between steel and concrete using both experimental and design-oriented analyses. Flexural capacity of such beams can be derived based on either yielding or buckling of steel depending on the generated steel–concrete interface shear bond simulating full or partial shear connections. Design equations are developed and their performance is validated through test results of 24 experimental beams with five different modes of strength-enhancement device. Design procedures for such beams are illustrated with calculated design examples. Such simple design procedures can be adopted in the actual design of thin-walled composite beams with various modes of strength-enhancement devices in practical applications.
Discovery of Small-Molecule Inhibitors of HCV NS3-4A Protease as Potential Therapeutic Agents against HCV Infection
Authors: Chen Shu-Hui , Tan Seng-Lai
Published: August 2005

Chronic infection with hepatitis C virus (HCV) is associated with liver cirrhosis that often leads to hepatic failure and hepatocellular carcinoma (HCC). HCV infection has become a global health threat and the main cause of adult liver transplants in developed nations. Current approved anti-HCV therapies (interferon and pegylated interferon alone or in combination with ribavirin) are not effective in eliminating the viral infection in a significant population of patients (e.g., those infected with HCV genotype 1). Furthermore, these therapies are plagued with many undesirable side effects. Therefore, the HCV epidemic represents a huge unmet medical need that has triggered intensive research efforts towards the development of more effective drugs. Given its essential role in the process of HCV replication, the viral NS3/4A serine protease is arguably the most thoroughly characterized HCV enzyme and the most intensively pursued anti-HCV target for drug development. This is further fueled by the successful use of small-molecule inhibitors of the human immunodeficiency virus (HIV) viral protease, which have had an impressive effect on HIV-related morbidity and mortality, offering hope that analogous drugs might also have a similar impact against HCV. Here, we review the recent progress and development of small-molecule inhibitors of the HCV NS3/4A protease. In particular, we focus on the discovery of VX-950, the latest HCV NS3-4A protease inhibitor to be advanced to clinical studies. While the challenges of designing potent inhibitors of the viral protease have been solved, as highlighted by BILN 2061 and VX-950, it is still too early to determine whether these efforts will eventually yield promising drug candidates. For the emerging small-molecule HCV inhibitors, viral resistance will likely be a big problem. Thus, combination therapy of different drugs with different targets/mechanisms will be necessary to effectively inhibit HCV replication. It is also hoped that a detail characterization of how the resistance mutations that affect NS3 inhibitor binding may provide useful information for the design of inhibitors with the potential to treat resistant viruses that may arise during chronic HCV infection.
Definition of an Uptake Pharmacophore of the Serotonin Transporter Through 3D-QSAR Analysis
Authors: Pratuangdejkul J. , Schneider B. , Jaudon P. , Rosilio V. , Baudoin E. , Loric S. , Conti M. , Launay J- M. , Manivet P.
Published: August 2005

The serotonergic system plays a critical role in a wide variety of physiological and behavioral processes. Dysregulation of the tightly controlled extracellular concentration of serotonin (5- hydroxytryptamine, 5-HT) appears to be at the origin of a host of metabolic and psychiatric disorders. Since the plasma membrane 5-HT transporter (SERT) is the major protagonist in regulating extracellular 5-HT concentration, SERT is the target of most drugs interacting with the serotonergic system. Unfortunately, some of the drugs towards SERT (e.g. amphetamine derivatives) interfere with cell homeostasis leading to cell toxicity. Developing new SERT ligands devoid of any side-effect represents a major priority in the treatment of 5-HT-associated pathologies. Here, we report structure-activity relationships (SAR) and three-dimensional QSAR (3D-QSAR) studies of a library of 121 compounds including 5-HT analogs, harmanes, benzothiazoles, indanones, amphetamine derivatives and substrate-type 5-HT releasers, with the goal of identifying the structural determinants crucial for SERT uptake. In the absence of data about the bioactive form of 5-HT, conformational analysis of 5-HT was performed using quantum chemistry calculations. This led to three 5-HT stable conformers with anti, -gauche and +gauche side-chain conformation. These conformers, used as templates for superimposition with all the library compounds, enabled the design of a reliable 6-points pharmacophore representative of SERT uptake activity. Molecular dynamics (MD) simulations performed with compounds that are efficiently, moderately, poorly or not transported by SERT allowed to assess the validity of our pharmacophore. Altogether, our data provide for the first time a reliable pharmacophore of SERT uptake activity, which may help to the design of new drugs targeting SERT.
Amphiphilic Transdermal Permeation Enhancers: Structure-Activity Relationships
Authors: Vavrova K. , Zbytovska J. , Hrabalek A.
Published: August 2005

Transdermal drug delivery offers numerous advantages over conventional routes of administration; however, poor permeation of most drugs across the skin barrier constitutes a serious limitation of this methodology. One of the approaches used to enlarge the number of transdermally-applicable drugs uses permeation enhancers. These compounds promote drug permeation through the skin by a reversible decrease of the barrier resistance. Enhancers can act on the stratum corneum intracellular keratin, influence desmosomes, modify the intercellular lipid domains or alter the solvent nature of the stratum corneum. Even though, hundreds of substances have been identified as permeation enhancers to date, yet our understanding of the structureactivity relationships is limited. In general, enhancers can be divided into two large groups: small polar solvents, e.g. ethanol, propylene glycol, dimethylsulfoxide and amphiphilic compounds containing a polar head and a hydrophobic chain, e.g. fatty acids and alcohols, 1-dodecylazepan-2-one (Azone), 2-nonyl-1,3- dioxolane (SEPA 009), and dodecyl-2-dimethylaminopropanoate (DDAIP). In this review we have focused on structure-activity relationships of amphiphilic permeation enhancers, including the properties of the hydrophobic chains, e.g. length, unsaturation, and branching, as well as the polar heads characteristics, e.g. hydrogen bonding ability, lipophilicity, and size. We present over 180 examples of enhancers with different polar head to illustrate the structural requirements and the possible role of the polar head. We have given an overview of the methods used for investigation of the mechanisms of permeation enhancement, namely differential scanning calorimetry (DSC), infrared (IR) and Raman spectroscopy, X-ray diffraction and future perspectives in this field. Furthermore, biodegradability and chirality of the enhancers are discussed.
Antisense Oligonucleotides: The State of the Art
Authors: Aboul-Fadl T.
Published: August 2005

The use of antisense oligonucleotides as therapeutic agents has generated considerable enthusiasm in the research and medical community. Antisense oligonucleotides as therapeutic agents were proposed as far back as in the 1970s when the antisense strategy was initially developed. Nonetheless, it has taken almost a quarter of a century for this potential to be realized. The principle of antisense technology is the sequencespecific binding of an antisense oligonucleotide to target mRNA, resulting in the prevention of gene translation. The specificity of hybridization by Watson-Crick base pairing make antisense oligonucleotides attractive as tools for targeted validation and functionalization, and as therapeutics to selectively modulate the expression of genes involved in the pathogenesis of diseases. The last few years have seen a rapid increase in the number of antisense molecules progressing past Phase I, II and III clinical trials. This review outlines the basic concept of the antisense technology, its development and recent potential therapeutic applications.
Thymidylate Synthase Structure, Function and Implication in Drug Discovery
Authors: Costi M. P. , Ferrari S. , Venturelli A. , Calo S. , Tondi D. , Barlocco D.
Published: August 2005

Recent methodologies applied to the drug discovery process, such as genomics and proteomics, have greatly implemented our basic understanding of drug action and are giving more input to medicinal chemists, in finding genuinely new targets and opportunities for the development of drugs with original mechanisms of action. In this paper, an example of the successful application of some new techniques to the target enzymes with the Thymidylate Synthase (TS) function is given. The improved knowledge of the complex mechanism of the biological pathways in which thymidylate synthase is involved represents a unique chance to find new mechanism-based inhibitors, aimed to treat not only cancerous diseases, but also infectious pathologies. Thymidylate synthase (TS or ThyA) has long been considered as one of the best-known drug targets in the anti-cancer area, after which old and new drugs, such as 5-fluoro uracil and the anti-folate ZD1694, have been introduced into chemotherapy to treat solid tumours. Only a few attempts have been made to find non-classical anti-folate inhibitors that are dissimilar to the folate co-factor, with the aim of finding unshared protein target domains on the enzyme structure, in order to specifically inhibit TS enzymes from pathogens. Only recently from omic studies, a new Thymidylate Synthase Complementing Protein (TSCP or ThyX) has been identified in a number of pathogens, showing a different structure with respect to human TS, thus opening new avenues to specific inhibitions. A depiction of the most recent progress in the study of Thymidylate Synthase enzymes is presented in the following sections.
Novel Approaches Towards Development of Non-Classical Platinum-Based Antineoplastic Agents: Design of Platinum Complexes Characterized by an Alternative DNA-Binding Pattern and/or Tumor-Targeted Cytotoxicity
Authors: Momekov Georgi , Bakalova Adriana , Karaivanova Margarita
Published: August 2005

Cisplatin is an essential antineoplastic agent whose introduction in clinical use revolutionized the treatment of several solid malignancies, especially those of germinative origin. The unfavorable toxicological profile of this drug, however as well as the resistance of some common malignancies solicited the search of platinum complexes, characterized by lower toxicity and/or broader antitumor spectrum. Thus during the last three decades a plethora of several thousand platinum coordination compounds have been synthesized and evaluated as potential antineoplastic agents. Despite of the numerous compounds investigated however only few of the proved to be of clinical significance and actually none of them could be considered as an ideal substitute for cisplatin regarding both lower toxicity and broader spectrum of anticancer activity. To a great extent the platinum-based drug discovery was confined at structural modification of the parent compound in line with the classic structure-activity relationship concept. Conversely, since the majority of platinum complexes developed so far are closely related structural analogues of cisplatin, it is not surprising that they produce similar cellular effects and any altered pattern of antitumor activity and/or toxicity is likely to be due to pharmacokinetic, rather than truly mechanistic, factors. Studies over the last few years have shown that the structural resemblance to cisplatin is not an absolute requirement for cytotoxicity, which broadens the search for cisplatin analogues towards non-classical compounds with prominent structural/pharmacodynamic dissimilarity to the prototype. This review covers the major approaches to elaboration of non-classical platinum complexes with emphasis on complexes interacting with DNA in a cisplatin-dissimilar fashion and complexes with tumor-targeted cytotoxicity.
Novel Treatments for Obesity and Osteoporosis: Targeting Apoptotic Pathways in Adipocytes
Authors: Nelson-Dooley C. , Della-Fera M. A. , Hamrick M. , Baile C. A.
Published: August 2005

Obesity and osteoporosis have grave consequences for human health, quality of life, and even the efficiency of the labor force and economy. However, these pathologies share a common cell progenitor, revealing a surprising target for drug research and development. Recent findings show that high adipocyte count in bone marrow is directly related to bone loss, as fat cells replace osteoblasts (or bone-forming cells). The objective of this review is to examine the importance of adipocyte apoptosis in the treatment of obesity and/or osteoporosis, with special emphasis on natural products as promising leads for drug development. We have induced in vivo adipocyte apoptosis, using leptin, ciliary neurotrophic factor (CNTF), beta adrenergic agonists and conjugated linoleic acid (CLA) in rodents. The results of leptin treatments on rats are suppressed food intake, reduced body weight, reduced body fat, adipocyte apoptosis, and elevated energy expenditure. Further, leptin treatment of leptin-deficient (ob/ob) mice increases endosteal bone formation and bone mineral density. Adipocyte apoptosis has also been induced in vitro using tumor necrosis factor-alpha (TNF-α), (-)-epigallocatechin gallate (EGCG) from Camellia sinensis and ajoene, from Allium sativum. Natural products have potential for inducing apoptosis of adipose tissue, inhibiting bone marrow adipogenesis and increasing the expression of osteogenic factors in bone, thereby yielding effective treatments for obesity and osteoporosis.
Silicate layer dispersion in copolymer/clay nanocomposites
Authors: Hasegawa Naoki , Tsukigase Azusa , Usuki Arimitsu
Published: August 2005

Factors of silicate layer dispersions in polymers have been studied with copolymers. The influence of the copolymerization ratio of copolymers and the alkyl chain lengths of organomodified reagents of organophilic clay has been examined. The dispersion of silicate layers in copolymers is dependent on the copolymerization ratios of the functional groups, that is, the polarity of the polymer matrix. The alkyl chain lengths of organomodified reagents also have an important influence on silicate layer dispersions. From a comprehensive viewpoint, the polarity matching between polymers and organophilic clay is an important factor for silicate layer dispersions in polymers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1554–1557, 2005
Comparison of morphology and properties of polyelectrolyte complex particles formed from chitosan and polyanionic biopolymers
Authors: Barck Karolina , Butler Michael F.
Published: August 2005

Beads containing a chitosan core and a polyelectrolyte complex (PEC) shell were formed by the dropwise addition of chitosan to solutions containing sodium alginate, gellan, pectin, κ‐carrageenan, or poly(acrylic acid). Hydrogel cores were formed by crosslinking chitosan with genipin, a natural bifunctional crosslinker. The shell thickness was generally only a few molecules thick and was impermeable to the transport of macromolecules but not low molecular weight molecules. Increasing the number of anionic groups and the strength of the chitosan–polyanion interaction through selection of different anionic species increased the mechanical strength of the PEC shell by increasing the number of interaction points in the shell. Because the core and shell swelled differentially, with the shell able to swell much less than the core, increasing the shell strength increasingly constrained the degree of swelling that could be attained for the entire bead. The degree of swelling could therefore be controlled via the mechanical properties of the shell, which could in turn be explained by the molecular structure of the PEC shell. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1581–1593, 2005
Conductivity of polyolefins filled with high‐structure carbon black
Authors: Yu J. , Zhang L. Q. , Rogunova M. , Summers J. , Hiltner A. , Baer E.
Published: August 2005

The electrical conductivities of various polyolefins filled with a high‐structure carbon black (CB) were studied. Typical percolation behaviors were observed in all of the materials studied. At a critical CB content, which defined the percolation threshold, CB formed conductivity pathways, and resistivity fell sharply from a value characteristic of an insulator into the range of 10–100 Ω cm. The dependence of the percolation threshold on the matrix viscosity was understood in terms of competing effects on CB dispersion during blending and CB flocculation during compression molding. For the conditions used in this study, polypropylene with a melt flow index of about 50 was optimum. Flocculation in the quiescent melt was studied directly by atomic force microscopy. Conductivity pathways formed over time by CB agglomeration. The temperature dependence of the percolation time was described by an Arrhenius relationship. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1799–1805, 2005
Substitution effects of methyl and trifluoromethyl groups on the physicochemical properties of epoxy resins
Authors: Lee Jae‐Rock , Jin Fan‐Long , Park Soo‐Jin
Published: August 2005

We studied the effects of functional groups on the physicochemical properties, such as rheological behavior, thermal stability, glass‐transition temperature, and electrical and mechanical properties, of 4,4′‐diaminodiphenyl methane (DDM) cured methyl‐substituted and trifluoromethyl‐substituted difunctional epoxy resins [i.e., 2‐diglycidylether of toluene (DGET) and 2‐diglycidylether of benzotrifluoride (DGEBTF)]. The DGEBTF/DDM system showed higher thermal stability and lower dielectric constant values than the DGET/DDM system. The impact strength of the DGEBTF/DDM system was significantly higher than that of the DGET/DDM system. The increase in intermolecular interactions because of the increasing polarity of the fluorine in the epoxy backbone was probably the key to these results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1860–1864, 2005
Poly(butylene succinate)/twice functionalized organoclay nanocomposites: Preparation, characterization, and properties
Authors: Chen Guang‐Xin , Kim Eung‐Soo , Yoon Jin‐San
Published: August 2005

A new method was attempted to improve the interaction between poly(butylene succinate) (PBS) and a commercially available organoclay, Cloisite 25A (C25A), by the addition of epoxy groups to the clay. Epoxy groups were grafted to C25A by a treatment with (glycidoxypropyl)trimethoxy silane to produce twice functionalized organoclay (TFC). Tethering PBS molecules to the epoxy groups on the surface of TFC was attempted through melt compounding. The morphological structure of the composites was analyzed with X‐ray diffractometry and transmission electron microscopy. The higher degree of exfoliation of the silicate layers in PBS/TFC and the improved mechanical properties, in comparison with those of PBS/C25A, were attributed to the increased interfacial interaction between PBS and TFC. TFC accelerated the crystallization of PBS more effectively than C25A, and this indicated that TFC was more efficacious for the nucleation than C25A. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1727–1732, 2005
Synthesis of polyurethane acrylates by hydrogenated castor oil and dimer‐based polyester diol and study on pressure‐sensitive adhesive
Authors: Ren Yaobin , Pan Huiming , Li Longsi , Xia Jianming , Yang Yongqiang
Published: August 2005

Synthesis of polyurethane acrylate (PUA) and preparation of the UV‐cured pressure‐sensitive adhesives (PSA) are reported. Molecular weight (Mw) (by gel permeation chromatography) and viscosity (η*) of PUA were measured. Characterization of PUA and PSA before and after UV‐curing was made by FTIR. Increase of the hydroxyls from hydrogenated castor oil/hydroxyls from dimer‐based polyester diol (OHHCO/OHDiol) ratio decreased the Mw and η* value of PUA. Dynamic viscoelastic properties (by dynamic rheological spectrometer) and performance of the UV‐cured PSA were also studied. Increase of the OHHCO/OHDiol ratio increased the storage modulus (G′), the loss modulus (G″), and complex viscosity (Eta*) of the UV‐cured PSA, which, in turn, enhanced holding power and shear adhesion failure temperature (SAFT) and yet decreased peeling strength. Substitution of OB for DBTDL depressed the Mw and η* value of PUA, while the G″ and Eta* values of the UV‐cured PSA were elevated, which, in turn, increased the holding power and SAFT and yet depressed the peeling strength. Elevation of the tackifying resin content depressed the G′, G″, and Eta* values of the cured PSA and yet increased glass transition temperatures (Tg) of PSA, measured by differential scanning calorimetry. Peeling strength of PSA elevated as increasing the tackifying resin, while the holding power and SAFT fell. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1814–1821, 2005
Studies on K2S2O8/ascorbic acid initiated synthesis of Ipomoea dasysperma seed gum‐g‐poly(acrylonitrile): A potential industrial gum
Authors: Singh Vandana , Tiwari Ashutosh , Sanghi Rashmi
Published: August 2005

Seed gum from Ipomoea dasysperma was grafted with polyacrylonitrile using potassium persulfate/ascorbic acid redox initiator in the presence of molecular oxygen, where the maximum percentage grafting and percentage efficiency observed were 360 and 97.2%, respectively. Optimal grafting conditions were established for the gum and a representative polyacrylonitrile grafted gum was characterized using FTIR, NMR, X‐ray diffraction, and TGA studies. Grafted gums with %G up to 185% showed water solubility; thereafter, the solubility in water was observed to decrease with the increase in %G. After the saponification of the nitrile groups to amide and carboxylic acid groups, the water retention of the grafted gum increased significantly and this increase was dependent on the extent of grafting. Various properties like viscosity, gel/film forming ability, shelf life of the grafted gum solutions (with samples where %G were not >185%) along with the water, and saline retention capacity were studied and compared with that of the parent gum to evaluate it for industrial applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1652–1662, 2005
Synthesis and swelling properties of pH‐sensitive hydrogels based on chitosan and poly(methacrylic acid) semi‐interpenetrating polymer network
Authors: Chen Shilan , Liu Mingzhu , Jin Shuping , Chen Yong
Published: August 2005

A novel semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of chitosan and poly(methacrylic acid) was synthesized using formaldehyde as a crosslinker. The amount of crosslinker was searched and optimized. The structure of the hydogel was investigated by Fourier transform infrared (FTIR) spectroscopy. The spectrum shows that a structure of polyelectrolyte complex exists in the hydrogel. The effects of pH, ionic strength, and inorganic salt on the swelling behaviors of the hydrogel were studied. The results indicate the hydrogel has excellent pH sensitivity in the range of pH 1.40 to 4.50, pH reversible response between pH 1.80 and 6.80, and ionic strength reversible response between ionic strength 0.2 and 2.0M. The results also show that the hydrogel has a bit higher swelling capacity in a mix solution of calcium chloride (CaCl2) and hydrochloric acid (HCl) solution than in a mix solution of sodium chloride (NaCl) and HCl. These results were further confirmed through morphological change measured by scanning electron microscope (SEM). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1720–1726, 2005
Interfacial modification of high density polyethylene/glass fiber reinforced and non reinforced polyamide 66 blends
Authors: Baouz T. , Fellahi S.
Published: August 2005

High density polyethylene (HDPE) and polyamide (PA66) are well known to be incompatible. An ionomer (Surlyn) was added as a compatibilizer to HDPE and glass fiber reinforced (HDPE/GFRPA66) and non‐reinforced (HDPE/PA66) blends. Two compositions were considered: 25/75 wt % and 75/25 wt %, with an emphasis on the former formulation. The influence of the compatibilizer on the rheology, thermal properties, and the morphology, as well as mechanical properties of the blends, was investigated using melt flow index measurements, DSC, scanning electron microscopy (SEM), and impact strength. The ionomer was found to be more effective as a compatibilizer with HDPE as a minor phase compared to the case when HDPE becomes the major phase. The results indicated that the interfacial properties of the blends were improved, with a maximum appearing at a critical concentration of the ionomer (7.5 vol %). At this level of compatibilization, SEM analysis revealed better interfacial adhesion and a finer dispersion. MFI results revealed a probable reaction between the amine groups of PA66 and the acid functions of the ionomer. The mechanical properties support the above results and showed that the addition of 25 wt % HDPE did not affect the properties of PA66 much and the presence of glass fiber did not hinder the effect of the compatibilizer. Only 20% decrease in notched Izod impact strength of the blends is observed at 7.5 vol % ionomer content, suggesting that the addition of 25 wt % of HDPE to PA66 is not detrimental at this level of compatibilization. The emulsification curve was established and revealed that, in terms of impact properties, the finer the particle size, the higher the impact strength corresponding to 7.5 vol % ionomer content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1748–1760, 2005
New optically active poly(amide–imide–urethane) thermoplastic elastomers derived from poly(ethylene glycol diols), 4,4′‐methylene‐bis(4‐phenylisocyanate), and a diacid based on an amino acid by a two‐step method under microwave irradiation
Authors: Mallakpour Shadpour , Rafiemanzelat Fatemeh
Published: August 2005

A new class of optically active poly(amide–imide–urethane)s (PAIUs) was synthesized via a two‐step diisocyanate route under microwave irradiation. In these reactions, 4,4′‐methylene‐bis(4‐phenylisocyanate) was reacted with bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine and poly(ethylene glycol diol)s (PEGs), such as PEG‐400, PEG‐600, PEG‐1000, and PEG‐2000, to furnish a series of new PAIUs. The effects of different reaction conditions, such as the method of preparation (polyol or acid chain extension), the prepolymerization step (NCO‐terminated oligoamide or NCO‐terminated polyether polyol), the irradiation time and power, the reaction solvent, the soft‐segment length, and the presence or absence of reaction catalysts (e.g., triethylamine, pyridine, and dibutyltin dilaurate), on the properties of the copolymers, including the solubility, viscosity, and thermal behavior, were investigated. The resulting multiblock copolymers had inherent viscosities of 0.15–0.53 dL/g. These multiblock copolymers were optically active, thermally stable, and soluble in amide‐type solvents. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1781–1792, 2005