bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave Activation of Electrochemical Processes at Glassy Carbon and Boron‐Doped Diamond Electrodes
Authors: Sur Ujjal Kumar , Marken Frank , Seager Robert , Foord John S. , Chatterjee Arnab , Coles Barry A. , Compton Richard G.
Published: January 2005

Voltammetric experiments under intense microwave field conditions have been carried out at a carbon microfiber electrode, an array of carbon microfiber electrodes, and at a boron‐doped diamond electrode. For the reversible one electron redox systems Fe(CN)$\rm{ {_{6}^{3-/4-}}}$ and Ru(NH3)$\rm{ {_{6}^{3+/2+}}}$ in aqueous KCl solution increased currents (up to 16 fold at a 33 μm diameter carbon microelectrode) and superheating (up to ca. 400 K at all types of electrodes) are observed. Electrodes with smaller diameter allow better signal enhancements to be achieved. From the missing effect of the supporting electrolyte concentration on the microwave enhanced currents, it can be concluded that effects observed at carbon electrodes (microwave absorbers) are due to the interaction of microwaves with the electrode material whereas for metal electrodes (microwave conductors) effects are dominated by the interaction of the microwaves with the aqueous dielectric. Short heat pulses can be applied by pulsing the microwave field and relatively fast temperature transients are observed for small electrodes. For the irreversible two electron oxidation of L‐dopa in aqueous phosphate buffer, different types of effects are observed at glassy carbon and at boron‐doped diamond. Arrays of carbon microfibers give the most reproducible and analytically useful current signal enhancements in the presence of microwaves.
Seed Mediated Growth of Gold Nanoparticles on Indium Tin Oxide Electrodes: Electrochemical Characterization and Evaluation
Authors: Zhang Jingdong , Kambayashi Miyako , Oyama Munetaka
Published: January 2005

The seed mediated growth of gold nanoparticles on indium tin oxide (ITO) surfaces is described, which provided a new method for the construction of gold nanoparticles‐modified ITO electrodes even without using conventional linker molecules, such as (3‐mercaptopropyl)trimethoxysilane (MPTMS). In this process, ultra‐small gold seeds were formed and anchored on the ITO surfaces first. When the seeds‐deposited ITO surfaces came into contact with the gold growth solution, the growth of gold nanoparticles occurred. The morphology of the as‐prepared modified surface was found to be strongly dependent upon the substrate. On an MPTMS‐silanized ITO, mostly gold nanospheres were formed (Au/MPTMS/ITO).In contrast, on a bare ITO, some high aspect ratio gold nanorods as well as large amounts of gold nanospheres were grown and directly attached (Au/ITO). The as‐prepared two gold nanoparticles‐modified ITO electrodes exhibited different electrochemical characteristics, attributed to the influence of MPTMS molecules. Compared with Au/MPTMS/ITO, the Au/ITO was more efficient in decreasing the heterogeneous charge transfer resistance and improving the reaction reversibility of [Fe(CN)6]3−/[Fe(CN)6]4− and exhibited more attractive bioelectrocatalytic properties. Due to the block effect of the thiol monolayer, Au/MPTMS/ITO depressed the selectivity for the determination of epinephrine (EP) in the presence of ascorbic acid (AA) while Au/ITO could improve the detection sensitivity and retain the selectivity.
Adsorptive Stripping Voltammetric Detection of Daunomycin at a Bismuth Bulk Electrode
Authors: Bučková Miriam , Gründler Peter , Flechsig Gerd‐Uwe
Published: January 2005

The bismuth electrode exhibits similar electrochemical properties as most commonly used toxic mercury electrode and represents a suitable, reliable and also environmentally friendly tool for the detection of electroactive compounds at negative potentials. A wide operational potential window of the bismuth electrode from −200 mV to −1400 mV (vs. SCE) was found. Bismuth bulk electrodes (BiBE) are very convenient for sensitive adsorptive stripping voltammetric (AdSV) determination of the drug daunomycin in the nmol/L concentration range. In comparison with gold electrodes, the voltammetric signals of daunomycin at the bismuth electrode are higher and very well shaped. An accumulation potential of −0.65 V (vs. SCE) and accumulation time from 2 to 10 min were found to be optimal conditions for the preconcentration of daunomycin on the bismuth electrode surface. The adsorptive stripping response is linear over 100–1000 nmol/L concentration range (for 2 min deposition) and over 10–100 nmol/L concentration range (for 5 min deposition) with a detection limit of 5 nmol/L (for 8 min deposition). Repeatability was characterized by relative standard deviation 7.1% (for 10 measurements). The electrode must be regenerated between two consecutive measurements by polishing on a damp paper or by stirring in 96% ethanol for 5 min.
Micro‐Imprinting of Oligonucleotides and Oligonucleotide Gradients on Gold Surfaces: A New Approach Based on the Combination of Scanning Electrochemical Microscopy and Surface Plasmon Resonance Imaging (SECM/ SPR‐i)
Authors: Fortin Elodie , Defontaine Yann , Mailley Pascal , Livache Thierry , Szunerits Sabine
Published: January 2005

A new strategy for the formation of DNA patterns on thin gold surfaces together with DNA hybridization is described. The formation and characterization of the oligonucleotide array is based on a combination of an electrochemical and an optical technique: scanning electrochemical microscopy and surface plasmon resonance imaging (SECM/SPR‐i). The DNA array is formed through electropolymerization of a mixture of pyrrole and pyrrole bearing covalently linked oligonucleotides probes using SECM. SPR‐i as well as fluorescence imaging are used to quantify DNA hybridization on these multi‐parametric interfaces. The capability of scanning electrochemical microscopy (SECM) to pattern gold surfaces with density gradients of oligonucleotides attached to the gold surfaces is further demonstrated. These density gradients result from the progressive increase in the movement of the x‐axis while applying continuous potential pulses to the gold surface. Surface plasmon resonance imaging is used to detect the deposition step, while fluorescence imaging is employed to visualize the deposited oligonucleotide density gradient.
New perspectives on Holocene landscape development in the southern English chalklands: The upper Allen valley, Cranborne Chase, Dorset
Authors: French C. , Lewis H. , Scaife R. , Allen M.
Published: January 2005

A combination of on‐ and off‐site paleoenvironmental and archaeological investigations of the upper Allen valley of Dorset, conducted from 1998–2002, has begun to indicate a different model of prehistoric landscape development to those previously put forward for this part of the southern English chalk downlands. Woodland growth in the earlier Holocene appears to have been slower and patchier than the presumed model of full climax deciduous woodland rapidly attained in a warming environment. With open areas still strongly present in the Mesolithic, the area witnessed its first exploitation, thus slowing and altering soil development. Consequently, many areas perhaps never developed thick, well‐structured, brown forest earths, but more probably thin brown earths. By the later Neolithic period, these soils had become thin rendzinas, largely as a consequence of human exploitation and the predominance of pastoral land use. The early presence of thinner and less well‐developed soils over large areas of downland removes the necessity for envisaging extensive soil erosion and the accumulation of thick colluvial and alluvial deposits in the dry valleys and valley floor as often postulated. If there were major changes in the vegetation and soil complexes in this area of chalk downland, these had already occurred by the Neolithic rather than the Bronze Age as often suggested, and the area has remained relatively stable ever since. This has major implications for models of prehistoric land use in the southern chalkland region, such as a much greater degree of stability in prehistoric and historic times, variability within sub‐regions, and differences between different parts of the chalk downlands than had previously been envisaged. © 2005 Wiley Periodicals, Inc.
Human impact, land‐use history, and the surface archaeological record: A case study from Greece
Authors: Bintliff John
Published: January 2005

Perhaps the most informative approach currently being applied in the Mediterranean to investigate regional settlement and land‐use histories is that of surface archaeological survey. Yet, the well‐known Holocene record of surface erosion and deposition in the region and an almost unparalleled timespan of sequent human occupance creates taphonomic problems in interpreting the surface archaeology. This paper will use case studies to illustrate the fruitful interaction of Holocene geoarchaeology and field survey in seeking to unravel these difficulties. ©2005 Wiley Periodicals, Inc.
Soil erosion and valley fills in the Yemen highlands and southern Turkey: Integrating settlement, geoarchaeology, and climate change
Authors: Wilkinson T. J.
Published: January 2005

Geoarchaeological studies of valley‐fill sequences frequently do not employ the full range of human activities to explain the causes of deposition. This paper shows how records of environmental change from ocean cores and relict lakes can be integrated with geoarchaeological sequences from land and the record of long‐term settlement and land use to provide a composite record of human–environmental interactions. On the high plains of Yemen, lakes and paleosols suggest that the ratio of precipitation to evaporation was higher between 12,000 and 7400 cal yr B.P. Atmospheric conditions then became drier from about 6000 cal yr B.P., after which time population increased and there was more evidence for human‐induced erosion. Therefore, during the late Holocene (i.e., approximately the last 4000 years), human settlement increased in the face of a somewhat drier climate. It is evident that settlement in the northern Fertile Crescent also increased in the face of a drier late Holocene climate. It is argued that many of the distinctive valley fills that are evident in both the northern Fertile Crescent and southern Arabia result from the combined effect of both increase of settlement together with some degree of climatic drying. © 2005 Wiley Periodicals, Inc.
Modeling landscapes and past vegetation patterns of New Mexico's Rio del Oso Valley
Authors: Periman Richard D.
Published: January 2005

Humans have interacted with the landscape and ecosystem of New Mexico's Rio del Oso Valley for thousands of years. Throughout the Holocene, various cultures have dramatically affected and altered the Rio del Oso. An interdisciplinary research approach, incorporating geomorphology, paleobotany, archaeology, and history, provides a broad range of methodologies and data sets of past landscape dynamics. Integrating such data sets in three‐dimensional Geographical Information Systems (GIS) models of past vegetation and landscape conditions may enable a view of anthropogenic ecosystem change. Analyses of past land use through landscape models, geoarchaeology, and other methods can provide a greater understanding for current and future ecosystem management. © 2005 Wiley Periodicals, Inc.*
Philinopside a, a novel marine‐derived compound possessing dual anti‐angiogenic and anti‐tumor effects
Authors: Tong Yunguang , Zhang Xiongwen , Tian Fang , Yi Yanghua , Xu Qiangzhi , Li Ling , Tong Linjiang , Lin Liping , Ding Jian
Published: January 2005

Philinopside A is a novel sulfated saponin isolated from the sea cucumber, Pentacta quadrangulari. The effects of philinopside A on angiogenesis and tumor growth were assessed in a series of models in vitro and in vivo. Our results demonstrated that philinopside A significantly inhibited the proliferation, migration and tube formation of human microvascular endothelial cells (HMECs) in a dose‐dependent manner, with average IC50 values of 1.4 ± 0.17, 0.89 ± 0.23 and 0.98 ± 0.19 μM, respectively. Rat aortas culture assay provides a close imitation of in vivo angiogenesis process and 2–10 μM philinopside A suppressed the formation of new microvessels in cultured rat aortas. Philinopside A 2–10 nmol/egg obviously inhibited angiogenesis in chick embryo chorioallantoic membrane assay. In addition, philinopside A manifested strong anti‐tumor activities both in vitro and in vivo. Through immunofluorescent analysis, we found the compound reduced mouse sarcoma 180 tumor volume by inducing apoptosis of tumor and tumor‐associated endothelial cells. An examination of the effects of philinopside A on the angiogenesis‐related receptor tyrosine kinases (RTKs) showed that philinopside A broadly inhibited all tested RTKs, including vascular endothelial growth factor (VEGF) receptor, fibroblast growth factor (FGF) receptor‐1, platelet‐derived growth factor (PDGF) receptor‐β and epithelial growth factor (EGF) receptor, with IC50 values ranging from 2.6–4.9 μM. These results suggest that philinopside A is a promising anti‐cancer agent that possesses dual cytotoxic and anti‐angiogenic effects that were at least partly due to its inhibitory effects on RTKs. © 2004 Wiley‐Liss, Inc.
Prediction of recurrence in advanced gastric cancer patients after curative resection by gene expression profiling
Authors: Motoori Masaaki , Takemasa Ichiro , Yano Masahiko , Saito Sakae , Miyata Hiroshi , Takiguchi Shuji , Fujiwara Yoshiyuki , Yasuda Takushi , Doki Yuichiro , Kurokawa Yukinori , Ueno Noriko , Oba Shigeyuki , Ishii Shin , Monden Morito , Kato Kikuya
Published: January 2005

The prognosis of patients with advanced gastric cancer remains unfavorable. Even after curative resection, 40% of patients with advanced gastric cancer die of recurrence. Conventional clinicopathlogic findings are sometimes inadequate for predicting recurrence in individuals. Hence, we tried to construct a new diagnostic system, which predicts recurrence in patients with advanced gastric cancer after curative resection based on molecular analysis. Gastric cancer progression is a function of multiple genetic events that may affect the expression of large number of genes. We performed gene expression profiling with 2,304 genes in 60 advanced gastric cancer patients who underwent curative resection using a PCR array technique, a high‐throughput quantitative RT‐PCR technique. The diagnostic system, which was constructed from the learning set comprised of 40 patients with the most informative 29 genes, classified each case into a good‐signature or poor‐signature group. Then, we confirmed the predictive performance in an additional test set comprised of 20 patients, and the prediction accuracy for recurrence was 75%. Kaplan‐Meier analysis revealed significant difference between the good‐signature and the poor‐signature group (p = 0.0125). Especially in patients with smaller tumor (≤ 5 cm), less developed LN metastasis (N0,1), or earlier stage (stages I and II), the prediction accuracy was high (88.9%, 84.6%, or 81.8%, respectively). Our diagnostic system based on systematic analysis of gene expression profiling can predict the recurrence at clinically meaningful level. By combining our system with conventional clinicopathologic factors, we can improve the prediction of recurrence in patients with advanced gastric cancer who underwent curative surgery. © 2004 Wiley‐Liss, Inc.
Peptide vaccination after repeated resection of metastases can induce a prolonged relapse‐free interval in melanoma patients
Authors: Letsch Anne , Keilholz Ulrich , Fluck Michael , Nagorsen Dirk , Asemissen Anne Marie , Schmittel Alexander , Thiel Eckhard , Scheibenbogen Carmen
Published: January 2005

This pilot study was carried out to gain a first insight into the effects of peptide vaccination in melanoma patients in the high‐risk adjuvant disease setting. From the adjuvant peptide vaccination studies carried out in our institution since 1998, we identified all melanoma patients with a history of at least 3 completely resected metastases during the year preceding enrollment into the trial and describe the clinical and immunologic observations. Out of a total of 44 patients with resected cutaneous melanoma entered into adjuvant peptide vaccination trials, 9 patients were identified with more than 3 metastases in the year before vaccination. After initiation of vaccination, 2 patients remained relapse‐free for 27 and 42+ months, 2 patients experienced single or several initial relapses and subsequent relapse‐free intervals of 18 and 65+ months, whereas 5 patients progressed. In both patients with relapse after prolonged relapse‐free intervals, the relapses were initially confined to the small intestine and could be resected. Induction or boosting of functional tyrosinase peptide‐specific T cells was noted in 6 of 8 patients, including all 4 patients with prolonged relapse‐free intervals. In conclusion, adjuvant peptide vaccination was associated with cessation of recurrences in 4 of 9 patients, of whom all 4 had an immunologic response to the vaccine. © 2004 Wiley‐Liss, Inc.
Predictions of mortality from pleural mesothelioma in Italy: A model based on asbestos consumption figures supports results from age‐period‐cohort models
Authors: Marinaccio Alessandro , Montanaro Fabio , Mastrantonio Marina , Uccelli Raffaella , Altavista Pierluigi , Nesti Massimo , Costantini Adele Seniori , Gorini Giuseppe
Published: January 2005

Italy was the second main asbestos producer in Europe, after the Soviet Union, until the end of the 1980s, and raw asbestos was imported on a large scale until 1992. The Italian pattern of asbestos consumption lags on average about 10 years behind the United States, Australia, the United Kingdom and the Nordic countries. Measures to reduce exposure were introduced in the mid‐1970s in some workplaces. In 1986, limitations were imposed on the use of crocidolite and in 1992 asbestos was definitively banned. We have used primary pleural cancer mortality figures (1970–1999) to predict mortality from mesothelioma among Italian men in the next 30 years by age‐cohort‐period models and by a model based on asbestos consumption figures. The pleural cancer/mesothelioma ratio and mesothelioma misdiagnosis in the past were taken into account in the analysis. Estimated risks of birth cohorts born after 1945 decrease less quickly in Italy than in other Western countries. The findings predict a peak with about 800 mesothelioma annual deaths in the period 2012–2024. Results estimated using age‐period‐cohort models were similar to those obtained from the asbestos consumption model. © 2004 Wiley‐Liss, Inc.
New method of dynamic color doppler signal quantification in metastatic lymph nodes compared to direct polarographic measurements of tissue oxygenation
Authors: Scholbach Thomas , Scholbach Jakob , Krombach Gabriele A. , Gagel Bernd , Maneschi Payam , Di Martino Ercole
Published: January 2005

Tumor growth depends on sufficient blood and oxygen supply. Hypoxia stimulates neovascularization and is a known cause for radio‐ and chemoresistance. The objective of this study was to investigate the use of a novel ultrasound technique for the dynamic assessment of vascularization and oxygenation in metastatic lymph nodes. Twenty‐four patients (age 44–78 years) with cervical lymph node metastases of squamous cell head and neck cancer were investigated by color duplex sonography and 17 (age 46–78 years) were investigated additionally with polarography. Sonography was performed after contrast enhancer infusion under defined conditions. Intranodal perfusion data (color hue, colored area) were measured automatically by a novel software technique. This allows an evaluation of blood flow dynamics by calculating perfusion intensity—velocity, perfused area, as well as the novel parameters tissue resistance index (TRI) and tissue pulsatility index (TPI)—for each point of a complete heart cycle. Tumor tissue pO2 was measured by means of polarographic needle electrodes placed intranodally. The sonographic and polarographic data were correlated using Pearson's test. Sonography demonstrated a statistically significant inverse correlation between hypoxia and perfusion and significant TPI and TRI changes with different N‐stages. The percentage of nodal fraction with less than 10 mmHg oxygen saturation was significantly inversely correlated with lymph node perfusion (r = −0.551; p = 0.021). Nodes with a perfusion of less than 0.05 cm/sec flow velocity showed significantly larger hypoxic areas (p = 0.006). Significant differences of TPI and TRI existed between nodes in stage N1 and N2/N3 (p = 0.028 and 0.048, respectively). This new method of dynamic signal quantification allows a noninvasive and quantitative assessment of tumor and metastatic lymph node perfusion by means of commonly available ultrasound equipment. © 2004 Wiley‐Liss, Inc.
A new analytical method for computing solvent‐accessible surface area of macromolecules and its gradients
Authors: Hayryan Shura , Hu Chin‐Kun , Skřivánek Jaroslav , Hayryane Edik , Pokorný Imrich
Published: January 2005

In the calculation of thermodynamic properties and three‐dimensional structures of macromolecules, such as proteins, it is important to have an efficient algorithm for computing the solvent‐accessible surface area of macromolecules. Here, we propose a new analytical method for this purpose. In the proposed algorithm we consider the transformation that maps the spherical circles formed by intersection of the atomic surfaces in three‐dimensional space onto the circles on a two‐dimensional plane, and the problem of computing the solvent‐accessible surface area is reduced to the problem of computing the corresponding curve integrals on the plane. This allows to consider only the integrals along the circular trajectories on the plane. The algorithm is suitable for parallelization. Testings on many proteins as well as the comparison to the other analogous algorithms have shown that our method is accurate and efficient. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 334–343, 2005
Two‐electron integrations in the Quantum Theory of Atoms in Molecules with correlated wave functions
Authors: Pendás A. Martín , Francisco E. , Blanco M. A.
Published: January 2005

A recent method proposed to compute two‐electron integrals over arbitrary regions of space [Martín Pendás, A. et al., J Chem Phys 2004, 120, 4581] is extended to deal with correlated wave functions. To that end, we use a monadic factorization of the second‐order reduced density matrix originally proposed by E. R. Davidson [Chem Phys Lett 1995, 246, 209] that achieves a full separation of the interelectronic components into one‐electron terms. The final computational effort is equivalent to that found in the integration of a one determinant wave function with as many orbitals as occupied functions in the correlated expansion. Similar strategies to extract the exchange and self‐interaction contributions from the two‐electron repulsion are also discussed, and several numerical results obtained in a few test systems are summarized. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 344–351, 2005
Improving gene replacement by intracellular formation of linear homologous DNA
Authors: de Piédoue G. , Maurisse R. , Kuzniak I. , Lopez B. , Perrin A. , Nègre O. , Leboulch P. , Feugeas J.‐P.
Published: January 2005

Background

Gene targeting is a potential tool for gene therapy but is limited by the low rate of homologous recombination. Using highly homologous linear DNA improves gene targeting frequency but requires microinjection into nuclear cells to be effective. Because transfection of circular DNA is more efficient than transfection of linear DNA and adaptable to viral vectors, we developed a system for the intracellular release of linear fragments from circular plasmids.

Methods

Only one cutting site inside the “donor” DNA was not convenient because it led to integration of exogenous sequences into the target. So we constructed several “donor” plasmids containing the homologous sequences flanked by two I‐Sce I recognition sites. Expression of I‐Sce I allowed intracellular delivery of “ends‐out” (replacement) vectors. We compared the efficiency of different constructions to correct a mutated gfp target.

Results

Co‐transfection of “donor” plasmids and an I‐Sce I expression vector into CHO cells enhanced the correction of an extrachromosomal mutated gfp target by at least 10 times. Maximum correction was observed with the greatest homology size and maximum effect of I‐Sce I was obtained when the long hemi‐sites of the duplicated I‐Sce I sites were contiguous to the homologous sequence. Unexpectedly, the reverse orientation of I‐Sce I sites provided little or no effect, probably due to the asymmetrical activity of the I‐Sce I meganuclease.

Conclusions

Releasing homologous DNA fragments with I‐Sce I enhances gene replacement. This work provides the basis for the future design of viral vectors for gene replacement. Copyright © 2005 John Wiley & Sons, Ltd.
Online laser beam monitoring by detection of scattered light from dielectric mirrors
Authors: Kaemling A , Hermann A , Ach F , Fischer C , Viöl W
Published: January 2005

An online laser beam monitoring system is presented in this article that detects the power distribution of the observed beam from the scattered light on dielectric deflecting mirrors. It is a simple possibility for determining the laser beam intensity profile during a laser treatment. The laser beam remains uninfluenced during the measurement. This technique provides high-resolution online information about a laser beam's power distribution and beam size. It is capable of monitoring cw or pulsed laser beams at different wavelengths. This measurement instrument can also be used for adjustment, beam localisation and for detecting power fluctuations in real time. Two different types of near infrared lasers were used to test the method: a semiconductor laser (λ = 808 nm) and a Nd:YAG laser (λ = 1064 nm). Several microscopic techniques, atomic force microscope (AFM) and white light interferometer (WLI), were used to measure the topography of the mirror surface. This information about the surface roughness is used for predicting information about the expected scattered light. A comparison with a reference system highlights the quality and the applications of this measurement technique.
Influence of Different Woven Geometry in Poly(propylene) Woven Composites
Authors: Houshyar Shadi , Shanks Robert A. , Hodzic Alma
Published: January 2005

Summary: The difference between the melting temperatures of poly(propylene) (PP) fibre and random poly(propylene‐co‐ethylene) (PPE) was exploited in order to establish processing conditions for an all PP composite. Under these conditions the matrix must be a liquid in order to ensure good wetting and impregnation at the fibres, though the temperature must not be too high to avoid melting the fibres. The high chemical compatibility of the two components allowed creation of strong physico‐chemical interactions, which favour strong interfacial adhesion. The static and dynamic mechanical properties and morphology of poly(propylene) woven fabric reinforced random PPE composites have been investigated with reference to the woven geometry that influenced the properties of the woven composites. Among the various cloth architectures that were used in the PP‐PPE composites, the satin weave imparted overall excellent mechanical properties due to the weave parameters, such as high float length and fibre count, low interlace point and crimp angle, etc. Morphology of the composite has been investigated by macro photography and scanning electron microscopy. Images from scanning electron microscopy provided confirmation of the above results by displaying the consolidation and good fibre‐matrix wetting of the composites.

Loss modulus of poly(propylene) woven‐matrix composites with different types of woven geometry.

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Loss modulus of poly(propylene) woven‐matrix composites with different types of woven geometry.
New Motivation for the Depolymerization Products Derived from Poly(Ethylene Terephthalate) (PET) Waste: a Review
Authors: Nikles David E. , Farahat Medhat S.
Published: January 2005

Summary: Over the last several decades, the process of recycling polymer waste has been attracting the attention of many scientists working on this issue. Polymer recycling is very important for at least two main reasons: firstly, to reduce the ever increasing volumes of polymer waste coming from many sources: from daily life packaging materials and disposables and secondly, to generate value‐added materials from low cost sources by converting them into valuable materials similar, to some extent, to virgin materials. Poly(ethylene terephthalate) (PET) occupies the top of the list of polymers to be recycled due to its easy recycling by different ways, which, in accordance, give variable products that can be introduced as starting ingredients for the synthesis of many other polymers. PET can by recycled by hydrolysis, acidolysis, alkalolysis, aminolysis, alcoholysis and glycolysis. Glycolysis is the breakdown of the ester linkages by a glycol, resulting in oligomers or oligoester diols/polyols with hydroxyl terminal groups. Oligoesters coming from the glycolysis of PET waste have been well known for a number of decades to be utilized as a starting material in the manufacture of polyurethanes, unsaturated polyesters and saturated polyester plasticizers. But, as a current motivation, we are reporting on a new application for these oligoester diols/polyols by converting the hydroxyl terminals into acrylate/methacrylate groups. These new acrylated/methacrylated oligoesters have been tested as UV curable monomers and gave promising results from the point of view of their curability by UV and their mechanical properties. The new motivations open the potential for the market to apply the depolymerization products of PET waste for UV curable coatings, useful for wood surfaces, paints and other applications.

Recycling of PET polymer by different chemical routes.

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Recycling of PET polymer by different chemical routes.
Supertoughness in Polysulfone/Poly(ethylene‐octene) Blends
Authors: Guerrica‐Echevarría Gonzalo , Eguiazábal José Ignacio , Nazábal Jon
Published: January 2005

Summary: Poly(sulfone of Bisphenol A) (PSU) based blends were obtained by melt blending PSU with up to 15 wt.‐% poly(ethylene‐octene) either modified with maleic anhydride (mPEO) or not (PEO). The dispersed particle size was small and similar in blends with PEO or mPEO. These facts indicated respectively that the interfacial tension was low and the lack of compatibilizing effect of mPEO. Some preferential presence of PEO in the outer surface of the specimens was observed, and was attributed to the large viscosity difference between the two components of the blends. This had no effect on the modulus of elasticity, but speeded up both the yield stress and ductility decreases at rubber contents above 3.25 wt.‐%. However, despite the immiscibility of the components, and thanks to the small particle size of the blends, super‐toughness was attained in the unmodified PSU/PEO blends. This was at PEO contents (3.25 wt.‐%) at which the modulus, yield stress and ductility of the blends were almost as good as those of pure PSU. It appeared that a change of the chemical nature of the rubber did not influence by itself super‐toughness, unless it was accompanied by either a morphological or adhesion change.

Impact strength of PSU‐based blends vs. PEO (○) or mPEO (•) content.

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Impact strength of PSU‐based blends vs. PEO (○) or mPEO (•) content.
Ethylene Polymerization using Combined Ni and Ti Catalysts Supported in situ on MAO‐Modified Silica
Authors: Junges Fernando , de Souza Roberto F. , dos Santos João H. Zimnoch , Casagrande Osvaldo L.
Published: January 2005

Summary: Branched polyethylene/linear polyethylene blends (BPE/LPE) were prepared using the combined Ni(α‐diimine)Cl2 (1) (α‐diimine = 1,4‐bis(2,6‐diisopropylphenyl)acenaphthenediimine) and {TpMs*}TiCl3 (2) (TpMs* = hydridobis(3‐mesitylpyrazol‐1‐yl)(5‐mesitylpyrazol‐1‐yl)) catalysts supported in situ on methylaluminoxane (MAO)‐modified silica (4.0 wt.‐% Al/SiO2). The polymerization reactions were performed in toluene at two different polymerization temperatures (0 and 30 °C) and several nickel molar fractions (xNi), using MAO as external cocatalyst. At all temperatures, the activities show an approximate linear correlation with xNi, indicating a non‐synergistic effect between the nickel and the titanium species. Higher activities were found at 0 °C. The melting temperatures for the polyethylene blends produced at 0 °C decrease as xNi increases in the medium, indicating good compatibility between the polyethylene phases made by both catalysts. The melting temperature (Tm) of the polyethylene blends was shown to depend on the order in which the catalysts were immobilized on the MAO‐modified silica support. The initial immobilization of 1 on the support (2/1/SMAO‐4) affords polymers with a lower Tm than those produced with 1/2/SMAO‐4. In addition, scanning electron microscopy (SEM) studies revealed that the spherical morphology of the supported catalyst is replicated in the polyethylene particles.

Influence of polymerization temperature on the activity of 1/2/SMAO‐4 with varying xNi.

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Influence of polymerization temperature on the activity of 1/2/SMAO‐4 with varying xNi.
Ring Polymers of Tubulin Induced by Binding of Natural Antimitotic Peptides
Authors: Sackett Dan L.
Published: January 2005

A number of natural products with potent antimitotic activity are peptides and depsipeptides that bind to tubulin, provoke depolymerization of microtubules, and induce formation of single layer rings of tubulin dimers. These peptides are all hydrophobic and small relative to tubulin (3‐5 amino acid residues), yet induce rings polymers with properties that can differ significantly in size and self‐association. In addition, these compounds exhibit potent cytotoxicity that varies by several hundred fold from one compound to another. Cryptophycin induces unusually homogeneous rings, composed of eight tubulin dimers, that are stable to dilution at least to nanomolar tubulin concentrations.
Studying Spatial Distributions of Influenza Hemagglutinin on the Plasma Membrane of Fibroblasts: A Work in Progress
Authors: Zimmerberg Joshua , Kumar Mukesh , Verma Anil , Farrington Jane , Roth Michael , Kenworthy Anne , Hess Samuel T.
Published: January 2005

The major envelope protein of influenza virus, hemagglutinin (HA), mediates the fusion of virus to cell for infection, and can mediate cell‐cell fusion. It has been studied as a “raft” protein, as it is found in detergent‐resistant membranes (DRM) and trafficks apically in polarized epithelia. Moreover, the viral envelope of influenza itself is rich in sphingomyelin and cholesterol. Using both immunogold electron microscopy and fluorescence resonance energy transfer (FRET) microscopy, we are examining the distribution of HA on the surface of fibroblasts expressing wild‐type HA.
Membrane Cholesterol and the Formation of Cholesterol Domains in the Pathogenesis of Cardiovascular Disease
Authors: Troup Gregory M. , Xie Yi , Boesze‐Battaglia Kathleen , Huang Yong , Kirk Terry , Hanley Francine , Tulenko Thomas N.
Published: January 2005

At least three types of cholesterol‐rich membrane domains have been described in biological membranes including cholesterol rafts, membrane caveolae and crystalline cholesterol domains,. While clear biological functions have been ascribed to both rafts and caveolae, little attention has been directed to the biological consequences of cholesterol enrichment of cell membranes and the formation of cholesterol domains. Elevated blood cholesterol levels have been shown to result in the enrichment of the cell plasma membrane with cholesterol in arterial smooth muscle cells (SMC), endothelial cells (EC) and cardiac myocytes. In the early period of cholesterol feeding (within days), the cell membrane enriches with cholesterol and membrane viscosity and membrane bilayer width increase. This latter effect severely alters membrane protein function, and recent data indicates that this induces the modulation of vascular cells (SMC and EC) to the atherosclerotic phenotype. In cardiac myocytes these membrane modifications appear to induce alterations in gene expression patterns that lead to the development of a heart failure phenotype. In addition, as the cholesterol content increases, phase separation of cholesterol occurs resulting in the formation of immiscible cholesterol domains within the membrane. These domains likely initiate nucleation of cholesterol crystals which would explain the origin of “cholesterol clefts” in atherosclerotic lesions. Taken together, these membrane alterations secondary to cholesterol enrichment constitute a “membrane lesion” which contribute to the very early pathogenic events underlying major human diseases including coronary artery disease, stroke and heart failure.
Alteration of Lipid Membrane Rigidity by Cholesterol and Its Metabolic Precursors
Authors: Petrache Horia I. , Harries Daniel , Parsegian V. Adrian
Published: January 2005

Caused by biosynthesis defects, cholesterol deficiency can lead to developmental disorders and malformations, with possible implication of lipid membrane properties. We show that modification of sterol chemical structure alters membrane physical properties significantly. By X‐ray diffraction and osmotic stress, we measure changes in the bending rigidity of bilayers containing either cholesterol or one of its metabolic precursors. Membrane elasticity differs dramatically between slightly different sterols and varies in the sequence lanosterol < 7‐dehydrocholesterol < lathosterol < cholesterol. We interpret the results in terms of sterol location within lipid structures and modification of lateral stress, a structural feature relevant to interactions within biological membranes. We find that cholesterol is most efficient in enhancing membrane rigidity, a possible clue to why depletion or replacement with other sterols can affect cellular structures.
Modeling the Electrostatics and Size Effect within a Crowded Bioenvironment
Authors: Li Zhidong , Wu Jianzhong
Published: January 2005

Biological fluids typically contain a large number of macromolecules occupying up to 40% of the total volume. Current understanding of the effect of high concentration, or ‘macromolecular crowding’, on cellular processes is primarily based on the excluded‐volume considerations in which all intermolecular interactions beyond the short‐ranged repulsion are neglected. In this work, a density functional theory (DFT) accompanied by Monte Carlo simulations is employed to investigate the structural and thermodynamic properties of a crowded cellular environment within the primitive model where biomacromolecules are represented by neutral and charged hard spheres and the solvent by a continuous dielectric medium. The performance of the DFT has been tested with extensive results from Monte Carlo (MC) simulations for the pair correlation functions (PCFs), excess internal energies, and osmotic coefficients under a variety of solution conditions.
Domain Size and Fluctuations at Domain Interfaces in Lipid Mixtures
Authors: Seeger Heiko M. , Fidorra Matthias , Heimburg Thomas
Published: January 2005

Biomembranes consist of a complex mixture of a large number of lipids and proteins. In such mixtures, microscopic domains and macroscopically separated phases may exist. Here, we discuss phase behavior and domains formation of binary lipid mixtures. We show that the domain formation is accompanied by large fluctuations at the domain boundaries, resulting in altered physical properties at the boundaries, for instance in a pronounced increase of the elastic constants. Therefore, we argue that the physics of the membrane depends on the overall length scale of its domains interfaces. We present here confocal microscopy images, calorimetric melting profiles and Monte‐Carlo simulations to understand the factors that determine domain formation, their sizes and the role of the domain interfaces.
Spontaneously Forming Unilamellar Phospholipid Vesicles
Authors: Yue Baohua , Huang Chien‐Yueh , Nieh Mu‐Ping , Glinka Charles J. , Katsaras John
Published: January 2005

Unilamellar vesicles (ULV) consisting of a single lipid bilayer are of special interest as drug delivery vehicles. Here, we report on a spontaneously forming ULV system composed of the short‐ and long‐chain phospholipids, dihexanoyl (DHPC) and dimyristoyl (DMPC) phosphorylcholine, respectively, doped with the negatively charged lipid, dimyristoyl phosphorylglycerol (DMPG). Small‐angle neutron scattering (SANS) and dynamic light scattering (DLS) were employed to systematically investigate the effects of lipid concentration, salinity, and time on vesicle stability. It is found that ULV size is practically constant over a range of lipid concentration and temperature. The spontaneously formed ULV are stable for periods of four months, or greater, without the use of stabilizers.
Structural Phase Behavior of High‐Concentration, Alignable Biomimetic Bicelle Mixtures
Authors: Nieh Mu‐Ping , Raghunathan V.A. , Glinka Charles J. , Harroun Thad , Katsaras John
Published: January 2005

The structures of bicelle mixtures composed of dimyristoyl and dihexanoyl phosphatidylcholines (DMPC and DHPC) with DMPC/DHPC molar ratios of 3.2 and 5 are characterized using polarized optical microscopy (POM) and small angle neutron scattering (SANS). Three phases, isotropic (I), chiral nematic (N*) and smectic (S) are observed as temperature (T) varies from 10 to 70 °C. The structure of the magnetically alignable N* phase, which was previously considered to be made up of discoidal micelles, is found to be composed of “ribbons”. Doping with the charged lipid, dimyristoyl phosphatidylglycerol (DMPG), which has the same 14:0 hydrocarbon chains as DMPC, results in a structural change of the aggregates where only the isotropic and smectic phases are observed. The smectic phase for the mixtures doped with DMPG is shear‐alignable and follows one‐dimensional swelling. However, at high‐T zwitterionic DMPC/DHPC mixtures form multi‐lamellar vesicles (MLV) with a relatively constant lamellar spacing of 66 Å, independent of water content.
Cover Picture: Macromol. Theory Simul. 1/2005
Authors: Vergara Alessandro
Published: January 2005

Cover: Distinct diffusion coefficients (${\rm D}^d_{ii}$, ${\rm D}^d_{i0}$ and ${\rm D}^d_{00}$) in the number fixed reference frame, DDCs, for the binary mixture PEG 200‐water as a function of the PEG weight fraction (Xg) are drawn. Values are evaluated according to the equation reported, where xi is a positional coordinate of a particle of species i, pointed brackets represent a canonical ensemble average, V is the total volume, N is the total number of particles in the system, t is the time. Real DDCs, in blue, are compared with a novel hard‐sphere (HS) based standard reference, in red.

Further details can be found in the Full paper by A. Vergara on page 21.
An efficient indirect RBFN‐based method for numerical solution of PDEs
Authors: Mai‐Duy Nam , Tran‐Cong Thanh
Published: January 2005

This article presents an efficient indirect radial basis function network (RBFN) method for numerical solution of partial differential equations (PDEs). Previous findings showed that the RBFN method based on an integration process (IRBFN) is superior to the one based on a differentiation process (DRBFN) in terms of solution accuracy and convergence rate (Mai‐Duy and Tran‐Cong, Neural Networks 14(2) 2001, 185). However, when the problem dimensionalityNis greater than 1, the size of the system of equations obtained in the former is aboutNtimes as big as that in the latter. In this article, prior conversions of the multiple spaces of network weights into the single space of function values are introduced in the IRBFN approach, thereby keeping the system matrix size small and comparable to that associated with the DRBFN approach. Furthermore, the nonlinear systems of equations obtained are solved with the use of trust region methods. The present approach yields very good results using relatively low numbers of data points. For example, in the simulation of driven cavity viscous flows, a high Reynolds number of 3200 is achieved using only 51 × 51 data points. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Molecular evolution of breast cancer
Authors: Simpson Peter T , Reis‐Filho Jorge S , Gale Theodora , Lakhani Sunil R
Published: January 2005

Molecular analysis of invasive breast cancer and its precursors has furthered our understanding of breast cancer progression. In the past few years, new multi‐step pathways of breast cancer progression have been delineated through genotypic–phenotypic correlations. Nuclear grade, more than any other pathological feature, is strongly associated with the number and pattern of molecular genetic abnormalities in breast cancer cells. Thus, there are two distinct major pathways to the evolution of low‐ and high‐grade invasive carcinomas: whilst the former consistently show oestrogen receptor (ER) and progesterone receptor (PgR) positivity and 16q loss, the latter are usually ER/PgR‐negative and show Her‐2 overexpression/amplification and complex karyotypes. The boundaries between the evolutionary pathways of well‐differentiated/low‐grade ductal and lobular carcinomas have been blurred, with changes in E‐cadherin expression being one of the few distinguishing features between the two. In addition, lesions long thought to be precursors of breast carcinomas, such as hyperplasia of usual type, are currently considered mere risk indicators, whilst columnar cell lesions are now implicated as non‐obligate precursors of atypical ductal hyperplasia (ADH) and well‐differentiated ductal carcinoma in situ (DCIS). However, only through the combination of comprehensive morphological analysis and cutting‐edge molecular tools can this knowledge be translated into clinical practice and patient management. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Molecular and cellular themes in cancer research: II
Authors: Hall Peter A , Lowe Scot W
Published: January 2005

Contemporary cancer research encompasses a broad range of activities spanning basic molecular and cell biology, in vitro and in vivo models and clinical studies. Much current activity in cancer research endeavours to translate the former through model systems into clinical practice. The purpose of the reviews in this issue is to exemplify the strategies and approaches used in such endeavours. The first group of reviews focus on specific key molecules of interest in cancer biology including elements of the cell cycle machinery, the WNT pathway and HOX genes, as well as the epigenetic regulation of cancer critical genes. The second cohort of reviews consider novel transgenic model systems and how such models can be non‐invasively imaged. The final reviews in this group consider the huge advances in our understanding of the p53 pathway and stress responses that have come from in vivo systems. Finally, the clinical relevance of these approaches is highlighted in essays on the use of gene profiling modern technologies to assess tumours of unknown origin, the molecular basis of breast cancer and gastrointestinal lymphoma, and the key area of drug resistance in cancer. These reviews highlight the multidisciplinary nature of current cancer research, which is increasingly having impact on patient care. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.