bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary patterns and risk of laryngeal cancer: An exploratory factor analysis in Uruguayan men
Authors: De Stefani Eduardo , Boffetta Paolo , Ronco Alvaro L. , Deneo‐Pellegrini Hugo , Acosta Giselle , Mendilaharsu María
Published: April 2007

Laryngeal carcinoma is a common malignancy among Uruguayan men. A number of case–control and prospective studies have studied the role of diet in this malignancy. To our knowledge, this is the first study that has explored broad dietary patterns by factor (principal components) analysis. The results of this study retained 6 dietary patterns. Pattern 5 (drinker) was directly associated with risk of laryngeal carcinoma (OR 3.8, 95% CI 1.9–7.5), whereas the Pattern 2 (healthy) was protective (OR 0.6, 95% CI 0.3–1.2). Finally, the Pattern 6 (western) displayed a significant increase in risk of 3.2 (95% CI 1.6–6.2). Most dietary patterns were associated with supraglottic cancer, supporting a possible etiological difference between supraglottic and glottic carcinomas. This study also suggests that the analysis of dietary patterns might be a useful approach for investigating nutritional factors implicated in laryngeal carcinogenesis. © 2007 Wiley‐Liss, Inc.
Chemical synthesis and in vitro biocompatibility tests of poly (L‐lactic acid)
Authors: Jahno Vanusca Dalosto , Mendes Ribeiro Gabriela Benderóvicz , dos Santos Luís Alberto , Ligabue Rosane , Einloft Sandra , Wimmers Ferreira Maidy Rehder , Bombonato‐Prado Karina Fittipaldi
Published: April 2007

Polylactic acid is a polymer of great technological interest, whose excellent mechanical properties, thermal plasticity, and bioresorbability render it potentially useful for environmental applications, as a biodegradable plastic and as a biocompatible material in biomedicine. This article discusses the synthesis and characterization of poly‐L‐lactic acid, obtained through two synthetic routes: direct polycondensation reactions without organic solvents, and in a supercritical medium. Tin complexes were used as catalysts in both polymerization reactions. The polymers were characterized by 1HNMR, IR, GPC, DSC, and TGA techniques. In vitro biocompatibility tests were performed with human alveolar bone osteoblasts and there were assessed cell adhesion, proliferation and viability. The poly condensation reaction proved to be an excellent synthetic route to produce PLA polymers with different molar mass. The formation of polymers from lactic acid monomer was confirmed through techniques utilized. It was observed that cell adhesion and viability was not disturbed by the presence of the polymer, although the proliferation rate was decreased when compared to control. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Pattern of body‐wall muscle differentiation during embryonic development of Enchytraeus coronatus (Annelida: Oligochaeta; Enchytraeidae)
Authors: Bergter Annette , Paululat Achim
Published: April 2007

The plesiomorphic arrangement of body‐wall musculature within the annelids is still under discussion. While polychaete groups show a great variety of patterns in their somatic muscles, the musculature of soil‐living oligochaetes was thought to represent the characteristic pattern in annelids. Oligochaete body‐wall muscles consist of an outer continuous layer of circular and an inner continuous layer of longitudinal muscles, forming a closed tube. Since designs of adult body musculature are influenced by evolutionary changes, additional patterns found during embryogenesis can give further information about possible plesiomorphic features. In oligochaetes, detailed cell‐lineage analyses document the origin of the mesoderm and consequently the muscles, but later processes of muscle formation remain unclear. In the present work, body‐wall muscle differentiation was monitored during embryogenesis of thesoil‐living oligochaete Enchytraeus coronatus (Annelida) by phalloidin staining. Primary circular muscles form in a discrete anterior‐to‐posterior segmental pattern, whereas emerging longitudinal muscles are restricted to one ventral and one dorsal pair of primary strands, which continuously elongate towards posterior. These primary muscles establish an initial muscle‐template. Secondary circular and longitudinal muscles subsequently differentiate in the previous spaces later in development. The prominent ventral primary longitudinal muscle strands on both sides eventually meet at the ventral midline due to neurulation, which moves the ventral nerve cord into a coelomic position, closing the muscle layers into a complete tube. This early embryonic pattern in E. coronatus resembles the adult body‐wall muscle arrangements in several polychaete groups as well as muscle differentiation during embryonic development of the polychaete Capitella sp. I. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
Reappraisal of patterns of nonmarine cryptodiran turtle carotid circulation: Evidence from osteological correlates and soft tissues
Authors: Jamniczky Heather A. , Russell Anthony P.
Published: April 2007

The turtle cranial circulation has been employed as an important source of phylogenetic information, but recent conflicting hypotheses of relationship within Testudinata suggest reevaluation of the utility of characters drawn from this complex. As a component ofa comprehensive character analysis, the osteological correlatesof the nonmarine cryptodiran turtle carotid circulation are herein subjected to high‐resolution X‐ray computed tomography, reassessed, and statistically investigated. Three different patterns of osteological correlates, indicating three disparate cranial circulatory patterns, are described, and this finding is corroborated by evidence from circulatory soft tissues. Members of the Trionychia and Kinosternoidea exhibit patterns that differ from the more widespread condition found in testudinoid taxa. This result differs from previous work, which has indicated the presence of only two major cranial circulatory patterns, and suggests that while cranial circulatory features may be phylogenetically informative, the information contained within them indicates patterns of relationship different from those previously hypothesized. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
Developmental strategy of the endoparasite Xenos vesparum (strepsiptera, Insecta): Host invasion and elusion of its defense reactions
Authors: Manfredini Fabio , Giusti Fabiola , Beani Laura , Dallai Romano
Published: April 2007

To successfully complete its endoparasitic development, the strepsipteran Xenos vesparum needs to elude the defense mechanisms of its host, the wasp Polistes dominulus. SEM and TEM observations after artificial infections allow us to outline the steps of this intimate host–parasite association. Triungulins, the mobile 1st instar larvae of this parasite, are able to “softly” overcome structural barriers of the larval wasp (cuticle and epidermis) without any traumatic reaction at the entry site, to reach the hemocoel where they settle. The parasite molts 48 h later to a 2nd instar larva, which moves away from the 1st instar exuvium, molts twice more without ecdysis (a feature unique to Strepsiptera) and pupates, if male, or develops into a neotenic female. Host encapsulation involves the abandoned 1st larval exuvium, but not the living parasite. In contrast to the usual process of encapsulation, it occurs only 48 h after host invasion or later, and without any melanization. In further experiments, first, we verified Xenos vesparum's ability to reinfect an already parasitized wasp larva. Second, 2nd instar larvae implanted in a new host did not evoke any response by hemocytes. Third, we tested the efficiency of host defense mechanisms by implanting nylon filaments in control larval wasps, excluding any effect due the dynamic behavior of a living parasite; within a few minutes, we observed the beginning of a typical melanotic encapsulation plus an initial melanization in the wound site. We conclude that the immune response of the wasp is manipulated by the parasite, which is able to delay and redirect encapsulation towards a pseudo‐target, the exuvia of triungulins, and to elude hemocyte attack through an active suppression of the immune defense and/or a passive avoidance of encapsulation by peculiar surface chemical properties. J. Morphol., 2007 © 2007 Wiley‐Liss, Inc.
Cyclic deformation behaviour and lifetime calculation of Al‐3Mg‐Mn
Authors: Rojek N. , Smaga M. , Walther F. , Eifler D.
Published: April 2007

Plastic strain amplitude, temperature and electrical resistance measurements were performed on the aluminium‐magnesium alloy Al‐3Mg‐Mn (AA5454) in recrystallised condition to describe and evaluate the cyclic deformation behaviour in detail. The endurance limit was estimated in load increase tests (LIT). In stress‐controlled single step tests at ambient temperature the cyclic deformation behaviour is characterised by pronounced cyclic hardening, which leads to a saturation state with a plastic strain amplitude of nearly zero. Due to far‐reaching cross effects of the applied measuring techniques, the plastic strain amplitude, the change of the specimen temperature due to cyclic plastic loading and the change of the electrical resistance show a strong interrelation with the underlying fatigue processes. A new lifetime calculation method “PHYBAL” on the basis of the plastic strain amplitude, the change of the temperature and the change of the electrical resistance yields an excellent accordance with experimentally determined lifetimes. Microstructural details were investigated by light and scanning electron microscopy.
Eigenspannungen als Messgröße zur Qualitätssicherung
Authors: Betzold J. , Pucelik J. , Eisenberg S.
Published: April 2007

Die röntgenografische Methode wird im Konzern der Volkswagen AG an diversen weltweiten Standorten als Standardverfahren zur Ermittlung von Eigenspannungen eingesetzt. Als wichtige Messgröße zur Qualitätssicherung sind die Eigenspannungen bei verschiedenen Bauteilen als Sollvorgaben in den Zeichnungen festgeschrieben (z. B. Getriebeteile, Federn). Die Messungen erfolgen im Bereich der Qualitätssicherung, in der Fertigung, der Schadensanalyse, der technischen Entwicklung und der Bemusterung der Bauteile von Lieferanten. Ein optimaler Nutzeffekt wird erzielt, wenn die Eigenspannungswerte eine eindeutige Korrelation mit der Bauteilbelastbarkeit ausweisen und wenn die Arbeitsprozesse zur Einbringung von Eigenspannungen mittels Eigenspannungsmessungen schon im Produktionsbereich optimiert werden können.
The effect of grain orientation on the tensile‐compressive asymmetry of polycrystalline NiTi shape memory alloy
Authors: Wang Y. F. , Yue Z. F. , Wang J.
Published: April 2007

The purpose of the present study is to thoroughly understand the influence of crystallographic texture on the stress‐strain asymmetric behavior of polycrystalline NiTi shape memory alloy under tension and compression. To do this, a 3D thermo‐mechanical model has been implemented in a finite element program and textured and untextured polycrystalline NiTi have been considered. In our polycrystalline finite element model, each element represents one grain and a set of crystal orientations which approximate the initial crystallographic texture of the NiTi are assigned to the elements. From the calculated results, it is found that the crystallographic texture is the important reason for the tension‐compression asymmetry. For the textured polycrystal, the tension‐compression asymmetry can be observed clearly, but for the polycrystal containing randomly oriented grains, the stress‐strain curves show low levers of asymmetry between tensile and compressive loading, and the evolutions of martensite volume fractions are similar under two stress states.
Continuous dependence on the geometry and on the initial time for a class of parabolic problems II
Authors: Philippin G. A. , Proytcheva V.
Published: April 2007

Extending the investigations initiated in an earlier paper, the authors deal in this paper with the solutions of another class of initial‐boundary value problems for which continuous dependence inequalities on the geometry and the initial time are established. Copyright © 2007 John Wiley & Sons, Ltd.
A method for removing global effects in small‐animal functional MRI
Authors: Lowe Andrew S. , Barker Gareth J. , Beech John S. , Ireland Matthew D. , Williams Steve C. R.
Published: April 2007

Global effects in functional MRI are temporal modulations in signal intensity resulting from various scanner and subject phenomena. These effects contribute to the overall variance, reducing the effect size associated with an experimental paradigm. Statistical estimations that include an approximation for concurrent global effects will reduce the residual error within the model and so improve statistical power of the study. Conventionally, estimates of global effects are derived from mean intracerebral signal intensities, but these may be prone to contributions from localised experimentally evoked signal changes. In such cases, inaccurate estimates of global effects may result in erroneous inferences of neural modulations based on statistical artefact. A novel, computationally simple, method of estimating global effects is proposed using muscle tissue acquired within the same acquisition volume. Quantitative improvements in sensitivity are reported for a somatosensory stimulation paradigm using global muscle signal intensities as a covariate of no‐interest. The method is independent of local neurogenic signal changes and, under particular experimental conditions, may be more representative of true global effects. The utility of this strategy to applications in small‐animal functional MRI that evoke systemic physiological changes as a result of the experimental manipulation is critically discussed. Copyright © 2007 John Wiley & Sons, Ltd.
An extended model and a column generation algorithm for the planar multicommodity flow problem
Authors: Alvelos Filipe , de Carvalho J. M. Valério
Published: April 2007

We present a new model and a column generation algorithm for the linear minimum cost multicommodity flow problem. The new model has two differences when compared to the classic formulation based on flows on paths: it has an additional set of variables and an additional set of inequalities. The extra variables are associated with flows on circuits where some arcs are reversed. The extra inequalities assure that an optimal solution to the extended model can be converted to an optimal solution to the path formulation. In order to obtain an optimal solution to the extended model, we use column generation. The extra variables are explicitly considered in the restricted master problem, from the beginning of the column generation process. The subproblem remains a set of shortest path problems. Our present work is related to the use of dual–optimal inequalities in the sense that we extend a model with additional primal variables/dual inequalities. However, our extended model also has additional primal inequalities/dual variables. We present computational results of our method in planar instances and compare them with standard column generation, a bundle method, and a general‐purpose solver. For the tested instances, there is an effective improvement in computational time of the column generation method when the extended model is used. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(1), 3–16 2007
Network design arc set with variable upper bounds
Authors: Atamtürk Alper , Günlük Oktay
Published: April 2007

In this paper we study the network design arc set with variable upper bounds. This set appears as a common substructure of many network design problems and is a relaxation of several fundamental mixed‐integer sets studied earlier independently. In particular, the splittable flow arc set, the unsplittable flow arc set, the single node fixed‐charge flow set, and the binary knapsack set are facial restrictions of the network design arc set with variable upper bounds. Here we describe families of strong valid inequalities that cut off all fractional extreme points of the continuous relaxation of the network design arc set with variable upper bounds. Interestingly, some of these inequalities are also new even for the aforementioned restrictions studied earlier. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(1), 17–28 2007
Joint optimization of pricing and resource allocation in competitive telecommunications networks
Authors: Bouhtou Mustapha , Erbs Guillaume , Minoux Michel
Published: April 2007

Yield management techniques have been used by companies in various competitive industrial contexts in order to keep a high level of revenue. With the opening of the telecommunications markets, operators are looking for ways of including competition in their decision process. By analyzing the customers' preferences, the market can be segmented into groups of similar preferences, and offers targeted to a particular market segment. In this paper, we study a problem of revenue management for a network operator offering services on end‐to‐end markets, while facing competition. We present a natural formulation for this problem that uses bilinear bilevel programming models, similar to those used in the airline industry [Côté et al., J Revenue Pricing Manage 2 (2003), 23–36]. However, such an approach leads to optimization problems that are very difficult to solve exactly on the large scale instances found in the telecommunications industry. To address difficulties solving large problems, we introduce a new alternative formulation for the problem, give a proof of NP‐hardness, and propose solution methods related to this formulation. The first one is an exact method based on a branch‐and‐bound algorithm; then we propose two approximate methods, one based on Lagrangian relaxation, and one based on a concave approximation of the objective function to be maximized. Comparative results are given. We show that this approach is practically efficient and leads to exact solutions for instances of telecommunications networks of a size larger than previously possible. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(1), 37–49 2007
A non‐linear programming method approach for upper bound limit analysis
Authors: Vicente da Silva M. , Antão A. N.
Published: April 2007

This paper presents a finite element model based on mathematical non‐linear programming in order to determine upper bounds of colapse loads of a mechanical structure.

The proposed formulation is derived within a kinematical approach framework, employing two simultaneous and independent field approximations for the velocity and strain rate fields. The augmented Lagrangian is used to establish the compatibility between these two fields. In this model, only continuous velocity fields are used.

Uzawa's minimization algorithm is applied to determine the optimal kinematical field that minimizes the difference between external and dissipated work rate. The use of this technique allows to bypass the complexity of the non‐linear aspects of the problem, since non‐linearity is addressed as a set of small local subproblems of optimization for each finite element.

The obtained model is quite versatile and suitable for solving a wide range of collapse problems. This paper studies 3D strut‐and‐tie structures, 2D plane strain/stress and 3D solid problems. Copyright © 2007 John Wiley & Sons, Ltd.
Assessment of anthrax vaccination data in the Defense Medical Surveillance System, 1998–2004
Authors: Payne Daniel C. , Rose Charles E. , Aranas Aaron , Zhang Yujia , Tolentino Herman , Weston Emily , McNeil Michael M. , Ruscio Bruce
Published: April 2007

Purpose

Understanding the completeness and accuracy of U.S. military anthrax vaccination data is important to the design and interpretation of studies to assess the safety of anthrax vaccine. We estimated the agreement between electronically recorded anthrax vaccination data in the Defense Medical Surveillance System (DMSS) versus anthrax vaccination data abstracted from hardcopy medical charts in a representative sample of the U.S. military from 1998 to 2004.

Methods

Medical chart abstractions were conducted at 28 military treatment facilities for 4201 personnel. Abstracted anthrax vaccination data for 1817 personnel, representing 7400 anthrax vaccine doses, were compared with electronically captured data in the DMSS from 1998 to 2004. Sensitivity, positive predictive value (PPV), specificity and negative predictive value (NPV) were calculated using weighted analyses.

Results

Weighted person‐level analysis revealed DMSS sensitivity = 93.8% (95%CI = 91.1, 95.8), specificity = 87.0% (79.0, 92.3), PPV = 85.6% (77.2, 91.3) and NPV = 94.5% (91.7, 96.4). Report of anthrax vaccination within a ±7 days window in both medical chart and DMSS electronic data had a sensitivity of 88.3% (85.4, 90.7) and a PPV of 86.6% (84.9, 88.2) in the vaccine dose‐level analysis.

Conclusions

These results support that anthrax vaccination data captured by the DMSS are adequate for post‐marketing surveillance investigations in the U.S. military and are of comparable quality to data captured by other vaccine safety databases. Copyright © 2007 John Wiley & Sons, Ltd.
Duration of therapy with metoclopramide: a prescription claims data study
Authors: Kaplan Sigal , Staffa Judy A. , Dal Pan Gerald J.
Published: April 2007

Purpose

Metoclopramide‐induced tardive dyskinesia is associated with cumulative drug exposure, which can result from prolonged use of the drug. We estimated therapy duration with metoclopramide, and measured the extent of therapy beyond the maximum time period of 12 weeks evaluated in the clinical trials and recommended in the label.

Methods

Prescription claims for metoclopramide from 2002 to 2004 were extracted for participants residing throughout the US and contained within the Caremark pharmacy benefit manager (PBM) database. An episode of therapy was defined as one or a series of consecutive claims with no more than a 30‐day lag between the dispensing date of a new claim and the ending date of the preceding claim. Episode duration was calculated by subtracting the start date from the end date for each episode.

Results

During the study period, almost 80% of participants (total = 200 907) had only one episode of therapy. The length of the longest episode for most patients (85%) varied from 1 to 90 days, yet 15% of the patients appeared to have received prescriptions for metoclopramide for a period longer than 90 days. Cumulative therapy for longer than 90 days was recorded for almost 20% of the patients.

Conclusions

These results suggest that despite the known risk of tardive dyskinesia and the labeled recommendations on duration of metoclopramide use, many patients appear to use the drug for relatively long time periods beyond the labeled recommendations. Physicians should carefully consider the risk‐benefit profile of the drug and, if possible, avoid increased risk of tardive dyskinesia due to prolonged exposure. Published in 2007 by John Wiley & Sons, Ltd.
Results of forty years Yellow Card reporting for commonly used perioperative analgesic drugs
Authors: Richardson Jennifer , Holdcroft Anita
Published: April 2007

Background

A variety of analgesics are used perioperatively and associated adverse drug reactions (ADRs) may complicate anaesthesia and recovery.

Methods

We aimed to measure the demographics of reported suspected ADRs to alfentanil, fentanyl, ketorolac, morphine, nalbuphine, papaveretum, pethidine and remifentanil. We report a retrospective analysis of Yellow Card reports of suspected ADRs from 1965–2004 as classified in the Adverse Drug Reaction On‐line Tracking database (ADROIT) of the Medicines and Healthcare products Regulatory Agency (MHRA).

Results

In total, 1312 reactions were retrieved. A single drug was reported in 908, 39 were fatal and 219 categorised as ‘allergic’. Allergic phenomenon varied from 2/33 (6%) for remifentanil to 11/53 (21%) for alfentanil. ‘Cardiovascular’ reactions were reported frequently with remifentanil (18/33, 55%) and alfentanil (19/53, 36%) and these generated a signal for possible hazards from proportional reporting ratios (PRRs). The opioid fentanyl was associated with similar hazard signals for muscular and psychiatric ADRs.

Conclusions

Perioperative vigilance may reduce morbidity and mortality from preventable ADRs to analgesic drugs. Denominator and diagnostic data are essential for prospective studies. Copyright © 2007 John Wiley & Sons, Ltd.
Aggregative structure of the 1‐octadecyl‐3‐methylimidazolium cation in the interlayer of montmorillonite and its effect on polypropylene melt intercalation
Authors: Ding Yunsheng , Xiong Renyan , Wang Sengshan , Zhang Xiaomin
Published: April 2007

A series of organomontmorillonites were synthesized from pristine sodium montmorillonite via ion exchange in toluene with 1‐octadecyl‐3‐methylimidazolium chloride, a kind of ionic liquid with high thermal stability, as a modifier. The amount and aggregative state of the 1‐octadecyl‐3‐methylimidazolium cation ([C18mim]+) adsorbed in the interlayer of organomontmorillonite (MMT) were investigated with thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), and differential scanning calorimetry. XRD patterns showed that [C18mim]+ was successfully intercalated into the interlayer of MMT, and the interlayer distances of the clays increased dramatically. On the basis of the TGA results, three types of arrangement models of [C18mim]+ could be seen, and they were related to the loading level of [C18mim]+ in the gallery of MMT. The effects of the aggregative structure of [C18mim]+ in the interlayer of MMT on polypropylene melt intercalation was also examined. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1252–1259, 2007
Integrated control of pests in tropical and subtropical sweet pepper production
Authors: Weintraub Phyllis G
Published: April 2007

Sweet pepper is now grown, in tropical and subtropical areas, under the integrated pest management (IPM) tactic of ‘physical barrier’, whereas it was once grown primarily in open fields. This management tactic, when properly employed, has the advantage of eliminating many of the larger open‐field pests, and has resulted in greatly increased pepper yields. However, certain other pest populations are exacerbated by this IPM tactic. This paper reviews the primary pests and current control tactics in sweet pepper. Copyright © 2007 Society of Chemical Industry
Effect of pyriproxyfen on developing stages and embryogenesis of California red scale (CRS), Aonidiella aurantii
Authors: Eliahu Miriam , Blumberg Daniel , Horowitz A Rami , Ishaaya Isaac
Published: April 2007

During the past decade, the insect growth regulator pyriproxyfen has been the most used insecticide for controlling the California red scale (CRS), Aonidiella aurantii (Maskell), an important pest in citrus groves worldwide. The aim of the present research was to develop bioassays for determining the effect of pyriproxyfen on developing stages and embryogenesis of CRS that can serve as baselines for monitoring resistance. Pyriproxyfen was very effective against first‐ and second‐instar nymphs of a susceptible strain of CRS; 0.1 and 0.2 mg AI L−1, resulting in 80 and 100% mortality of first‐instar nymphs, and in 62.5 and 91.7% mortality of second‐instar nymphs respectively. According to probit analysis, the LC50 and LC90 values of pyriproxyfen for first‐instar nymphs were 0.03 and 0.15 mg AI L−1, and for second‐instar nymphs they were 0.05 and 0.25 mg AI L−1 respectively. Pyriproxyfen was quite effective on first‐instar nymphs of a CRS field strain originating from a citrus grove where two successive applications of the compound had been applied. Mortality rates were 86 and 100% at concentrations of 0.2 and 0.4 mg AI L−1 respectively. Pyriproxyfen suppressed embryogenesis when CRS females were treated with pyriproxyfen. Young CRS females treated with 1.0 and 5.0 mg AI L−1 pyriproxyfen produced 6.6 N1/F and 2.4 N1/F as compared with 10.9 N1/F in untreated control. Copyright © 2007 Society of Chemical Industry
Managing arable weeds for biodiversity
Authors: Storkey Jonathan , Westbury Duncan B
Published: April 2007

As a result of the recent intensification of crop production, the abundance and diversity of UK arable weeds adapted to cultivated land have declined, with an associated reduction in farmland birds. A number of questions need to be addressed when considering how these declines can be reversed. Firstly, can the delivery of crop production and biodiversity be reconciled by spatially separating cropping from designated wildlife areas? A number of subsidised environmental schemes in the UK take this approach and are focused on establishing vegetation cover on uncropped land. However, because of the lack of regular disturbance in these habitats, they are dominated by perennials and they therefore have limited potential for promoting the recovery of annual weed populations. A number of farmland bird species also rely on the provision of resources in field centres, and it is therefore likely that the recovery of their populations will rely on weed management options targeted at the cropped areas of the field. This raises two further questions. Firstly, is it possible to identify beneficial weed species that are relatively poor competitors with the crop and also have biodiversity value? Secondly, are the tools available to manage these species at acceptable levels while controlling pernicious weeds? A number of approaches are being employed to answer these questions, including predicting yield loss from weed competition models and exploiting herbicide selectivity. The further development of these tools is crucial if farmer opposition to managing weeds in crops is to be overcome. Copyright © 2007 Society of Chemical Industry
Understanding interactions of gastric inhibitory polypeptide (GIP) with its G‐protein coupled receptor through NMR and molecular modeling
Authors: Malde Alpeshkumar K. , Srivastava Sudha S. , Coutinho Evans C.
Published: April 2007

Gastric inhibitory polypeptide (GIP, or glucose‐dependent insulinotropic polypeptide) is a 42‐amino acid incretin hormone moderating glucose‐induced insulin secretion. Antidiabetic therapy based on GIP holds great promise because of the fact that its insulinotropic action is highly dependent on the level of glucose, overcoming the sideeffects of hypoglycemia associated with the current therapy of Type 2 diabetes. The truncated peptide, GIP(1–30)NH2, has the same activity as the full length native peptide. We have studied the structure of GIP(1–30)NH2 and built a model of its G‐protein coupled receptor (GPCR). The structure of GIP(1–30)NH2 in DMSO‐d6 and H2O has been studied using 2D NMR (total correlation spectroscopy (TOCSY), nuclear overhauser effect spectroscopy (NOESY), double quantum filtered‐COSY (DQF‐COSY), 13C‐heteronuclear single quantum correlation (HSQC) experiments, and its conformation built by MD simulations with the NMR data as constraints. The peptide in DMSO‐d6 exhibits an α‐helix between residues Ile12 and Lys30 with a discontinuity at residues Gln19 and Gln20. In H2O, the α‐helix starts at Ile7, breaks off at Gln19, and then continues right through to Lys30. GIP(1–30)NH2 has all the structural features of peptides belonging to family B1 GPCRs, which are characterized by a coil at the N‐terminal and a long C‐terminal α‐helix with or without a break. A model of the seven transmembrane (TM) helices of the GIP receptor (GIPR) has been built on the principles of comparative protein modeling, using the crystal structure of bovine rhodopsin as a template. The N‐terminal domain of GIPR has been constructed from the NMR structure of the N‐terminal of corticoptropin releasing factor receptor (CRFR), a family B1 GCPR. The intra and extra cellular loops and the C‐terminal have been modeled from fragments retrieved from the PDB. On the basis of the experimental data available for some members of family B1 GPCRs, four pairs of constraints between GIP(1–30)NH2 and its receptor were used in the FTDOCK program, to build the complete model of the GIP(1–30)NH2 : GIPR complex. The model can rationalize the various experimental observations including the potency of the truncated GIP peptide. This work is the first complete model at the atomic level of GIP(1–30)NH2 and of the complex with its GPCR. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
The sequence TGAAKAVALVL from glyceraldehyde‐3‐phosphate dehydrogenase displays structural ambivalence and interconverts between α‐helical and β‐hairpin conformations mediated by collapsed conformational states
Authors: Patel Sunita , Balaji Petety V. , Sasidhar Yellamraju U.
Published: April 2007

The peptide TGAAKAVALVL from glyceraldehyde‐3‐phosphate dehydrogenase adopts a helical conformation in the crystal structure and is a site for two hydrated helical segments, which are thought to be helical folding intermediates. Overlapping sequences of four to five residues from the peptide, sample both helical and strand conformations in known protein structures, which are dissimilar to glyceraldehyde‐3‐phosphate dehydrogenase suggesting that the peptide may have a structural ambivalence. Molecular dynamics simulations of the peptide sequence performed for a total simulation time of 1.2 µs, starting from the various initial conformations using GROMOS96 force field under NVT conditions, show that the peptide samples a large number of conformational forms with transitions from α‐helix to β‐hairpin and vice versa. The peptide, therefore, displays a structural ambivalence. The mechanism from α‐helix to β‐hairpin transition and vice versa reveals that the compact bends and turns conformational forms mediate such conformational transitions. These compact structures including helices and hairpins have similar hydrophobic radius of gyration (Rgh) values suggesting that similar hydrophobic interactions govern these conformational forms. The distribution of conformational energies is Gaussian with helix sampling lowest energy followed by the hairpins and coil. The lowest potential energy of the full helix may enable the peptide to take up helical conformation in the crystal structure of the glyceraldehyde‐3‐phosphate dehydrogenase, even though the peptide has a preference for hairpin too. The relevance of folding and unfolding events observed in our simulations to hydrophobic collapse model of protein folding are discussed. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Conformational solution studies of the anti‐microbial temporin A retro‐analogues by using NMR spectroscopy
Authors: Kamysz Wojciech , Mickiewicz Beata , Greber Katarzyna , Rodziewicz‐MotowidŁo Sylwia
Published: April 2007

Temporin A (TA) is a small, basic and highly hydrophobic peptide, isolated from the skin of the European red frog, Rana temporaria. The TA (FLPLIGRVLSGIL‐NH2) displays a broad spectrum of anti‐microbial activity against Gram‐positive bacteria and fungi Candida albicans. In this study we investigate the solution structure of two TA retro‐analogues, (6‐1)(7–13)‐TA (GILPLFRVLSGIL‐NH2) and retro‐TA (LIGSLVRGILPLF‐NH2) by using nuclear magnetic resonance (NMR). The 3D solution structure of the analogues was established by using inter‐proton distances and vicinal coupling constants in the Simulated Annealing (SA) calculations (XPLOR program). The NMR conformational studies show the existence of the helical structure in the middle part of the (6‐1)(7–13)‐TA peptide and an unordered structure of the retro‐TA analogue under the D3‐TFE/H2O (3:7, v/v) conditions. Our investigations have shown that the hydrophobic cluster at N‐terminus with the Pro amino acid residue in position 3 or 4, the helical structure and the amphipathic character of the peptide are responsible for the anti‐microbial activity of the TA analogues. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Peptides and proteins in a confined environment: NMR spectra at natural isotopic abundance
Authors: Pastore Annalisa , Salvadori Severo , Temussi Piero Andrea
Published: April 2007

Confinement of proteins and peptides in a small inert space mimics the natural environment of the cell, allowing structural studies in conditions that stabilize folded conformations. We have previously shown that confinement in polyacrylamide gels (PAGs) is sufficient to induce a change in the viscosity of the aqueous solution without changing the composition and temperature of the solvent. The main limitation of a PAG to run NMR experiments in a confined environment is the need for labelling the peptides. Here we report the use of the agarose gel to run the NMR spectra of proteins and peptides. We show that agarose gels are completely transparent in NMR experiments, relieving the need for labelling. Although it is necessary to expose biomolecules to fairly high temperatures during sample preparation, we believe that this is not generally an obstacle to the study of peptides, and found that the method is also compatible with temperature‐resistant proteins. The mesh of agarose gels is too wide for direct effects of confinement on the stability of proteins but confinement can be easily exploited to interact the proteins with other reagents, including crowding macromolecules that can eventually lead to fold stabilization. The use of these gels is ideally suited for low‐temperature studies; we show that a very flexible peptide at subzero temperatures is stabilized into a well‐folded conformation. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Application of gel‐phase 19F NMR spectroscopy for optimization of solid‐phase synthesis of a hydrophobic peptide from the signal sequence of the mucin MUC1
Authors: Pudelko Maciej , Kihlberg Jan , Elofsson Mikael
Published: April 2007

This paper describes the manual Fmoc/t‐Bu solid‐phase synthesis of a difficult nine‐residue hydrophobic peptide LLLLTVLTV from one of the signal sequences that flank the tandem repeat of the mucin MUC1. Gel‐phase 19F NMR spectroscopy was used as a straightforward method for optimization of the solid‐phase synthesis. Different approaches were applied for comparative studies. The strategy based on modified solid‐phase conditions using DIC/HOAt for coupling, DBU for Fmoc deprotection, and the incorporation of the pseudo proline dipeptide Fmoc‐Leu‐Thr(ψMe, Me pro)‐OH as a backbone‐protecting group was found to be superior according to gel‐phase 19F NMR spectroscopy. Implementation of the optimized Fmoc protocol enabled an effective synthesis of signal peptide LLLLTVLTV. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Spectra of differential gain and linewidth enhancement factor in InGaAsN/GaAs single quantum well structures
Authors: Wartak M. S. , Weetman P.
Published: April 2007

The differential gain and linewidth enhancement factor (α ‐factor) of a new material system InGaAsN/GaAs is studied using the 10‐band k · p Hamiltonian matrix. A self‐consistent scheme which involves simultaneous solution of the Schrödinger and Poisson equations is applied. It is shown that spectra of differential gain and α ‐factor have significant variation versus nitrogen composition and carrier density. The determined parameters and their variations play important role in designing practical structures based on InGaAsN/GaAs material system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanocrystalline MgB4O7:Dy for high dose measurement of gamma radiation
Authors: Lochab S. P. , Pandey A. , Sahare P. D. , Chauhan R. S. , Salah Numan , Ranjan Ranju
Published: April 2007

Magnesium borate activated by dysprosium (MgB4O7:Dy) is a low‐Zeff, tissue‐equivalent material that is commonly used for medical dosimetry of ionizing radiations such as gamma and X‐rays using the thermoluminescence (TL) technique. Nanocrystals of the same material are produced and their TL characteristics are studied. It is found that the nanocrystalline MgB4O7:Dy with a dopant concentration of 1000 ppm is the most sensitive amongst varying dopant concentrations, with its sensitivity equal to 0.025 times that of the standard phosphor CaSO4:Dy. The glow curve has two peaks at 154 °C and 221 °C. The nanophosphor has very poor sensitivity for low doses up to 10 Gy but beyond this dose the phosphor exhibits a linear response up to 5000 Gy. On increasing the dose further the response first becomes supralinear and then sublinear, finally resulting into saturation. Considering also its low fading particularly under post‐irradiation annealing and excellent reusability features, this nanophosphor may be used for high dose (10–5000 Gy) measurements of ionizing radiations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lithium‐ion insertion in anodic TiO2 nanotubes resulting in high electrochromic contrast
Authors: Hahn Robert , Ghicov Andrei , Tsuchiya Hiroaki , Macak Jan M. , Muñoz Andres G. , Schmuki Patrik
Published: April 2007

The present work investigates lithium insertion into highly ordered nanotubular layers of TiO2 and its electrochromic effects. The nanotubes were formed by anodization of titanium in 1 M (H3PO4) + 1 M (NaOH) + 0.5wt% HF electrolyte at 20 V. This leads to nanotubular layers with a thickness of 1 ± 0.1 µm, individual tube diameter of 100 ± 10 nm and a tube wall thickness of 10 ± 2 nm. The cathodic behavior of tubes in the “as formed” amorphous phase and annealed to anatase were studied in a solution of 1 M LiClO4 in acetonitrile. Cyclic voltammograms and potential step experiments combined with reflectance measurements show for anatase nanotubes a well defined uptake potential for Li+ and a very strong and reversible electrochromic effect, while on the other investigated TiO2 structures the effects were much less pronounced. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Doping in silicon nanostructures
Authors: Iori F. , Ossicini S. , Degoli E. , Luppi E. , Poli R. , Magri R. , Cantele G. , Trani F. , Ninno D.
Published: April 2007

We report on an ab initio study of the structural, electronic and optical properties of boron and phosphorous doped silicon nanocrystals. The scaling with the Si‐nanocrystal size is investigated for both the neutral formation energies (FE) and the impurity activation energies. Both these energies scale with the nanocrystal inverse radius. The optical properties reveal the existence of new absorption peaks in the low energy region related to the presence of the impurity. The effects of B and P co‐doping show that the formation energies are always smaller than those of the corresponding single‐doped cases due to both carriers compensation and minor structural distortion. Moreover in the case of co‐doping the electronic and optical properties show a strong reduction of the band gap with respect to the pure silicon nanocrystals that makes possible to engineer the photoluminescence properties of silicon nanocrystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Macro porous silicon as pump media for electro‐osmotic pumps
Authors: Wallner J. Z. , Nagar N. , Friedrich C. R. , Bergstrom P. L.
Published: April 2007

Micro pumps are a critical component in micro fluidic systems. Due to its ability to generate high flow‐rate/pressure without using any moving parts, electro‐osmotic (EO) pumps are an appealing candidate for micro applications. As part of the effort to produce miniaturized EO pumps, macro porous silicon (PS) with high aspect ratio pores has been investigated as the pump media. Initial tests in a meso‐scale pump body produced a maximum pressure of 5.2 kPa and a very large flow rate of 11.9 μl min–1 mm–2 at 60 V, demonstrating macro PS as a promising material for micro scale, high flow‐rate/pressure EO pumps. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sum frequency generation from planar and porous silicon in contact with liquids
Authors: Kolasinski Kurt W. , DeWitt Kristy M. , Harrison Ian
Published: April 2007

Sum frequency generation (SFG) involving an ultrafast infrared pulse and a 787 nm up‐conversion pulse mixed at the surface of planar or porous Si as well as planar GaAs has been studied. We demonstrate that SFG data can be obtained while porous silicon is in contact either with an aqueous solution or ethanol. The nonresonant SFG signal responds to the chemical composition of the interface. It is also found that ultrafast 787 nm pulses can induce photochemistry between hydrogen‐terminated porous silicon and either aqueous HCl, ethanoic HF, or ethanol. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of delta poly‐type quasiregular dielectric structures made of porous silicon
Authors: Agarwal V. , Escorcia‐Garcia J. , Mora‐Ramos Miguel E.
Published: April 2007

To investigate the reflection of light in quasi‐regular dielectrics, we study here the optical properties of porous‐silicon‐based Fibonacci, Thue‐Morse and Period Doubling heterostructures. The multilayered systems are fabricated in such a way that each element in the two‐block substitutional sequence has a poly‐type structure. Both delta‐like and traditional configurations are considered. The results for the optical transmittance are analyzed and compared with the classical periodic structure. Numerical simulation for the transmittance along the lines of the transfer matrix approach is also presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous silicon‐based polymer replicas formed by bead patterning
Authors: Park Jennifer S. , Meade Shawn O. , Segal Ester , Sailor Michael J.
Published: April 2007

Monodisperse, micrometer‐sized polymer beads can be imparted with a porous nanostructure by softening them into a porous silicon photonic crystal template. Infiltration of the polymer and replication of the photonic spectral properties is verified by optical reflectivity measurements of the beads as they infuse into the nanostructure. The polymer beads can be removed from the porous Si template by dissolution of the template with a basic solution. This treatment destroys the photonic properties, although scanning electron microscopy (SEM) reveals that some nanotexturing remains in the polymer beads. This simple, solvent‐free process provides a means to produce nanotextured particles of controllable size and shape. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous silicon‐based potentiometric biosensor for triglycerides
Authors: Setzu S. , Salis S. , Demontis V. , Salis A. , Monduzzi M. , Mula Guido
Published: April 2007

In this paper we report on the fabrication and characterization of a potentiometric biosensor for the detection of triglycerides. This is constituted by a lipase immobilized on a mesoporous Si matrix. Prototypes, realized on 1 × 1 cm n+‐type silicon wafers, show a very high enzymatic activity. Moreover the properties of these biosensors have been shown to be stable in a several months time interval, clearly showing their advantages with respect to traditional triglycerides detection systems. The Michaelis Menten curve is obtained to demonstrate the absence of diffusion problems. Potentiometric measurements are also shown. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using a porous silicon photonic crystal for bacterial cell‐based biosensing
Authors: Alvarez Sara D. , Schwartz Michael P. , Migliori Ben , Rang Camilla U. , Chao Lin , Sailor Michael J.
Published: April 2007

This work demonstrates a method for non‐invasively monitoring the growth and Φ6 virus infection of Pseudomonas syringae bacteria using a 1‐D porous silicon photonic crystal and a white‐light source coupled to a CCD spectrometer. Bacteria growth on porous Si leads to increased scattering efficiency that can be measured as a change in intensity of light reflected from a 1‐D porous Si photonic crystal. A linear relationship between bacteria concentration and intensity of light at the photonic resonance is observed, and detection limits are similar to those obtained from optical density measurements. Upon infection with virus, decreases in scattered light intensity are observed at times that correlate with cell lysis caused by viral replication and subsequent bursting of bacteria cells. It is shown that measurements can be performed in real‐time and in an incubator where cells remain in their ideal environment throughout the experiment. This method is well‐suited for cell‐based biosensing, because bacteria cells can be monitored remotely without the need for sampling cells for plating or optical density measurements. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)