bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas‐phase fragmentation of protonated C60‐pyrimidine derivatives
Authors: Ramos Catarina I. V. , Santana‐Marques M. G. , Enes Roger F. , Tomé Augusto C. , Cavaleiro José A. S. , Nogueras Manuel
Published: February 2009

Electrospray ionization mass spectrometry/mass spectrometry (ESI/MS/MS) and multiple stage mass spectrometry (MSn, n > 2) were used in the positive ion mode, with two different types of mass spectrometers, a quadrupole time‐of‐flight and an ion trap, to characterize two sets of different types of C60‐aminopyrimidine exohedral derivatives. In one set, the pyrimidine moiety bears an amino acid methyl ester residue, and in the other the pyrimidine ring is part of a nucleoside‐type moiety, the latter existing as two separated diastereoisomers.

We have found that retro‐cycloaddition processes occur for the closed shell protonated species formed by electrospraying C60 derivatives synthesized by Diels–Alder reactions, whereas for the C60 derivatives synthesized via 1,3‐dipolar cycloadditions, these processes did not occur. Formation of diagnostic ions allowed the differentiation between the two groups of fullerene derivatives, and between the diastereoisomers of C60 derivatives with a nucleoside‐type moiety. In general, the fragmentation processes are strongly dependent on the protonation sites and on the structure of the exohedral moieties. Copyright © 2009 John Wiley & Sons, Ltd.
Experimental and theoretical Raman and surface‐enhanced Raman scattering study of cysteine
Authors: Diaz Fleming Guillermo , Finnerty Justin J. , Campos‐Vallette Marcelo , Célis Freddy , Aliaga Alvaro E. , Fredes Carlos , Koch Rainer
Published: February 2009

Raman spectra in solid and 1 M solution of L‐cysteine and surface‐enhanced Raman scattering (SERS) spectra of this molecule in the zwitterionic form, by using colloidal silver nanoparticles, have been recorded. Density functional theory with the B3LYP functional was used for the optimizations of the ground state geometries and simulation of the vibrational spectrum of this amino acid. The SERS spectrum with a large silver cluster as a model metallic surface was simulated for the first time. Taking into account the experimental and calculated Raman and SERS vibrations and the corresponding assignments, as well as a comparison of force constants and geometrical parameters between the free zwitterion cysteine and the one in the presence of the colloidal silver nanoparticles, we can confirm the presence of gauche (PH) and trans (PN) rotamers in the solid state, the formation of a SS bond in the solution state, the dissociation of the peptide bond and mixing of rotamers because of the SERS effect, and the relative importance of the interaction of sulphyldryl, NH3+, and carboxylate groups with the metallic surface. Copyright © 2009 John Wiley & Sons, Ltd.
Facile synthesis of micron‐sized hollow copper spheres with ZSM‐5 molecular sieve as a template
Authors: Xia Lixin , Liu Guangye , Wang Jian , Luo Song
Published: February 2009

A new, well‐designed type of micron‐sized hollow copper spheres was synthesized in this article. The process was performed using ZSM‐5 molecular sieve as a template. It has the prominent advantage in that the various stages of pretreatment for the core material can be omitted because of the inherent nature of the ZSM‐5 molecular sieve. The surface of the sieve consists entirely of negatively charged oxygen sites such that free Cu2+ ions can easily be adsorbed and reduced there, acting thereafter as a seed and self‐catalyst for electroless plating of copper so as to lead to the formation of interconnected Cu particles around the external surface of the ZSM‐5 molecular sieve. Moreover, there are many holes with a size of more than 5 × 5 Å2 on the surface of the ZSM‐5 molecular sieve, which can act as concavities that the reduced Cu can ‘rivet’ into, resulting in the link between the molecular sieve and the reduced Cu being stronger. In addition, the ZSM‐5 molecular sieve has the merits of ease of removal, low cost, and less aggregation owing to its micrometer size, and it avoids the use of nonvolatile surfactants, which may be adsorbed onto the reduced Cu and then interfere with the possible application of the hollow copper spheres in catalysis and in analytical devices based on surface‐enhanced Raman scattering (SERS) spectroscopy. The copper spheres obtained show enhanced Raman scattering in the presence of adsorbed 4‐mercaptobenzoic acid (4‐MBA) with excitation at 632.8 nm, and the enhancement factor reaches ∼7 × 103. The new micron‐sized hollow copper spheres are produced in a simple and cost‐effective method; so they are expected to play an important role in the fields of catalysts, fillers, and engineering, and in the development of SERS‐based analytical devices. The synthetic method may represent a novel route to prepare hollow metal spheres, which is a subject of intense interest. Copyright © 2009 John Wiley & Sons, Ltd.
Observing hydrogen silsesquioxane cross‐linking with broadband CARS
Authors: Caster Allison G. , Kowarik Stefan , Schwartzberg Adam M. , Nicolet Olivier , Lim Sang‐Hyun , Leone Stephen R.
Published: February 2009

Broadband coherent anti‐Stokes Raman scattering microscopy (CARS microscopy) is used for real‐time measurements of in situ cross‐linking of the photoresist material hydrogen silsesquioxane (HSQ). Using samples baked at different temperatures, and therefore cross‐linked to varying degrees, characteristic Raman bands are identified for the open ‘cage’ structure (345 cm−1, 454 cm−1 and 562 cm−1) as well as the cross‐linked ‘network’ structure (484 cm−1). Cross‐linking can also be induced by absorption of high intensity near‐infrared (IR) laser light (∼1013 W cm−2) and followed in real time by monitoring the characteristic Raman bands. Using the time resolution of CARS to follow the HSQ reaction during the laser exposure, a two‐stage kinetic process is observed and associated time constants of 20 ± 10 s and 3 ± 1 min are determined for the IR laser‐induced cross‐linking in films of ∼1 µm thickness. Copyright © 2009 John Wiley & Sons, Ltd.
Raman spectra and structure of a 25mer HCV RNA
Authors: Carmona Pedro , Molina Marina , Rodríguez‐Casado Arantxa
Published: February 2009

We have employed Raman spectroscopy to investigate the conformation of an (Hepatitis C virus) HCV RNA 25mer (1–25 nucleotides) in solution. The principal findings of this study are (1) the A‐form secondary structure involving C3′‐endo/anti ribofuranose pucker is predominant; (2) some uridine and guanosine nucleoside residues adopt the C2′‐endo/anti and C3′‐endo/syn conformations, respectively, which appear in looped nucleotide sequences; and (3) six out of nine guanine residues are base‐paired probably forming a stem. These results are interpreted as formation of a hairpin whose secondary structure is consistent with that proposed on the basis of phylogenetic comparisons with other viral RNAs. Copyright © 2009 John Wiley & Sons, Ltd.
Enhancements in intensity and thermal stability of Raman spectra based on roughened gold substrates modified by underpotential deposition of silver
Authors: Liu Yu‐Chuan , Yang Kuang‐Hsuan , Hsu Ting‐Chu
Published: February 2009

In this study, electrochemically roughened gold is modified with underpotential deposition (UPD) silver to investigate the effects on enhancements in the intensity and the thermal stability of surface‐enhanced Raman scattering (SERS). The SERS of Rhodamine 6G (R6G) adsorbed on the UPD Ag‐modified Au substrate exhibits a higher intensity by six‐fold of magnitude, as compared with that of R6G adsorbedon the unmodified Au substrate. Moreover, the SERS enhancement capabilities of UPD Ag‐modified Au and unmodified Au substrates are seriously depressed at temperatures higher than 200 and 150 °C, respectively. It indicates that the modification of UPD Ag can significantly depress the thermal destruction of SERS‐active substrates. Copyright © 2009 John Wiley & Sons, Ltd.
The chip‐processing potential of four potato (Solanum tuberosum L.) cultivars in response to long‐term cold storage and reconditioning
Authors: Kyriacou Marios C , Siomos Anastasios S , Ioannides Ioannnis M , Gerasopoulos Dimitrios
Published: February 2009

BACKGROUND: The reconditioning potential of four potato cultivars (Diamant, Hermes, Lady Rosetta and Spunta) was evaluated in three years of crop production. After 30, 60, 120 and 150 days of storage at 4.5 °C, cultivars were reconditioned at 16 °C for 0, 15 and 30 days before being evaluated for sprout growth, tuber fresh weight loss (FWL), sucrose content, reducing sugar (RS) content (sum of glucose and fructose contents) and chip fry colour (FCL).

RESULTS: Reconditioning induced rapid sprouting and pronounced FWL after 120 days of storage. Storage (30–150 days) was not critical to FCL and RS but affected sucrose levels. All cultivars showed an improvement in FCL and a reduction in RS and sucrose after reconditioning. The increment in FCL improvement and RS and sucrose depletion was greater between days 0 and 15 of reconditioning than between days 15 and 30 of reconditioning. Year contribution was significant to FCL and RS but not to sucrose variance. Acceptable FCL was attained after 15 days of reconditioning of Hermes and after 30 days for Lady Rosetta, while Diamant and Spunta remained substandard. RS levels in response to reconditioning were lowest in Hermes and Lady Rosetta.

CONCLUSION: FCL conformed to tuber RS accumulation profiles. Cultivar RS ranking following reconditioning remained unaltered from year to year throughout storage. RS and FCL during the first 30 days of cold storage may be a reliable comparative index of reconditioning potential, as high‐RS‐accumulating and poor‐chipping cultivars exhibit inadequate response to reconditioning. Tuber sucrose appeared of little significance as an index of the reconditioning ability of cultivars. Copyright © 2009 Society of Chemical Industry
Less common applications of monoliths: IV. Recent developments in immobilized enzyme reactors for proteomics and biotechnology
Authors: Krenkova Jana , Svec Frantisek
Published: February 2009

Use of monolithic supports for enzyme immobilization has rapidly expanded since we published the preceding paper in the series of articles concerned with this topic almost three years ago. Many groups worldwide have realized the benefits of applying monoliths as support structures and used a variety of techniques to immobilize many different enzymes. Although some of these new developments are just refinements of the methods developed previously, some notable new approaches have also been reported. This review summarizes the literature published since 2006 and demonstrates the broad variability of reactive monoliths prepared from silica as well as from organic polymers in the form of disks, columns, and capillaries. All these monoliths were prepared by direct formation from reactive precursors or activation of preformed inactive structures. Interestingly, most of the applications of monolithic enzyme reactors target proteolytic digestion of proteins for proteomic analysis.
Quercetin‐induced apoptotic cascade in cancer cells: Antioxidantversusestrogen receptor α‐dependent mechanisms
Authors: Galluzzo Paola , Martini Chiara , Bulzomi Pamela , Leone Stefano , Bolli Alessandro , Pallottini Valentina , Marino Maria
Published: February 2009

The flavonol quercetin, especially abundant in apple, wine, and onions, is reported to have anti‐proliferative effects in many cancer cell lines. Antioxidant or pro‐oxidant activities and kinase inhibition have been proposed as molecular mechanisms for these effects. In addition, an estrogenic activity has been observed but, at the present, it is poorly understood whether this latter activity plays a role in the quercetin‐induced anti‐proliferative effects. Here, we studied the molecular mechanisms of quercetin committed to the generation of an apoptotic cascade in cancer cells devoid or containing transfected estrogen receptor α (ERα;i.e., human cervix epitheloid carcinoma HeLa cells). Although none of tested quercetin concentrations increase reactive oxygen species (ROS) generation in HeLa cells, quercetin stimulation prevents the H2O2‐induced ROS production both in the presence and in the absence of ERα. However, this flavonoid induces the activation of p38/MAPK, leading to the pro‐apoptotic caspase‐3 activation and to the poly(ADP‐ribose) polymerase cleavage only in the presence of ERα. Notably, no down‐regulation of survival kinases (i.e., AKT and ERK) was reported. Taken together, these findings suggest that quercetin results in HeLa cell death through an ERα‐dependent mechanism involving caspase‐ and p38 kinase activation. These findings indicate new potential chemopreventive actions of flavonoids on cancer growth.
Application of item response theory to achieve cross‐cultural comparability of occupational stress measurement
Authors: Tsutsumi Akizumi , Iwata Noboru , Watanabe Naotaka , de Jonge Jan , Pikhart Hynek , Fernández‐lópez Juan Antonio , Xu Liying , Peter Richard , Knutsson Anders , Niedhammer Isabelle , Kawakami Norito , Siegrist Johannes
Published: February 2009

Our objective was to examine cross‐cultural comparability of standard scales of the Effort–Reward Imbalance occupational stress scales by item response theory (IRT) analyses. Data were from 20,256 Japanese employees, 1464 Dutch nurses and nurses' aides, 2128 representative employees from post‐communist countries, 963 Swedish representative employees, 421 Chinese female employees, 10,175 employees of the French national gas and electric company and 734 Spanish railroad employees, sanitary personnel and telephone operators. The IRT likelihood ratio model was used for differential item functioning (DIF) and differential test functioning (DTF) analyses. Despite the existence of DIF, most comparisons did not show discernible differences in the relations between Effort–Reward total score and level of the underlying trait across cultural groups. In the case that DTF was suspected, excluding an item with significant DIF improved the comparability. The full cross‐cultural comparability of Effort–Reward Imbalance scores can be achieved with the help of IRT analysis. Copyright © 2009 John Wiley & Sons, Ltd.
The effects of nonprofit brand equity on individual giving intention: mediating by the self‐concept of individual donor
Authors: Hou Jundong , Du Lanying , Tian Zhilong
Published: February 2009

Currently nonprofit organizations have to rely more on individual donors and less on the government for funding. Therefore, understanding the individual donor from the perspective of nonprofit has been of increasing interest to nonprofit marketers. In this research, the effects of nonprofit organizational brand equity and individual self‐concept on individual giving intention were studied by using survey to selected 393 valid respondents in China. The empirical results indicated that, (1) the three dimensions brand personality, brand image, and brand awareness of the nonprofit organization has positive direct impact on individual giving intention; (2) brand personality and brand awareness of the nonprofit organization has positive direct impact on the self‐concept of individual donor; (3) the self‐concept of individual donor has positive direct impact on individual giving intention; and (4) the self‐concept of individual donor mediates significantly the relationships between brand personality, brand awareness, and individual giving intention, while not significantly between brand image and individual giving intention.

Copyright © 2009 John Wiley & Sons, Ltd.
Formation and properties of supramolecular hydrogels based on 1,2,4,5‐benzene tetracarboxylic acid and 2‐amino‐3‐hydroxy pyridine
Authors: Kono Shunji , Wang Yu‐jiang , Tang Li‐ming
Published: February 2009

On the basis of 1H NMR analysis of the model complexes formed from ortho‐, meta‐, and para‐phthalic acid with 2‐amino‐3‐hydroxy pyridine (AHP), it was found that the two carboxyl groups located at the ortho position of the benzene ring more easily interact with AHP than those at meta‐ and para positions. A series of gelators (defined at G1–G5) were prepared from 1,2,4,5‐benzene tetracarboxylic acid (BTCA) and AHP at different molar ratios, and their structures were analyzed by 1H NMR and FT‐IR. The gelation performances of the gelators were investigated in details, which indicated that G3 formed at the BTCA/AHP molar ratio of 1.0/2.3 possessed the shortest gelation time, the lowest minimal gelation concentration (MGC), and the highest maximal gel‐to‐sol dissociation temperature (Tgel). The xerogels were analyzed by SEM and powder X‐ray diffraction, especially, the single crystal of G1 obtained directly from the gelling solvent showed complicated hydrogen bonded networks which were a direct evidence to explain the connecting network of the molecules. Based on this, the gelation properties were discussed. The relationship between the structures and properties of the gels is helpful for understanding the gelating mechanism and designing new gelators. Copyright © 2009 John Wiley & Sons, Ltd.
Mechanical and thermal properties of polypropylene nanocomposites using organically modified Indian bentonite
Authors: Patel Hasmukh A. , Joshi Ghanshyam V. , Pawar Radheshyam R. , Bajaj Hari C. , Jasra Raksh V.
Published: February 2009

We report preparation and characterization of nanoclay from Indian bentonite and imported nanoclays, and their compounding with polypropylene (PP) and maleic anhydride‐grafted PP (MA‐g‐PP) in twin screw extruder. The compounded polymer/nanoclay nanocomposites (PNCs) are molded into a standard specimen for studying its tensile, flexural and impact strength. A wide angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM) study demonstrates intercalation of PP in nanoclays rather than exfoliation for both, indigenous and imported nanoclays. The tensile modulus increased by 41 and 39% for PNC1 (PNC with imported nanoclay) and PNC2 (PNC with indigenous nanoclay) with respect to PP. The flexural modulus for PNC1 and PNC2 also increases by 23 and 22% due to incorporation of 5% nanoclay in PP along with 5% MA‐g‐PP. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Postnatal management and outcome for neural tube defects including spina bifida and encephalocoeles
Authors: Thompson Dominic N. P.
Published: February 2009

The incidence of neural tube defects (NTDs) has declined in recent decades, however myelomeningocele and encephalocele still represent one of the commoner prenatally diagnosed congenital malformations. Improved perinatal and post natal care mean that the mortality associated with these conditions has also fallen. Advances in the multidisciplinary management of children with myelomeningocele have led to significant improvements in functional outcome for many with this condition. However, there remains a substantial population of patients born with NTDs whose life expectancy is substantially reduced and who suffer significant cognitive and physical disability remaining wholly or partially dependant on the care of others into adult life.

This article aims to outline the contemporary early management of these conditions and examine the prospects for functional outcome where possible, attempting to show how early anatomical features of these conditions can help predict where, along the wide spectrum of outcome, a given individual may lie. Copyright © 2009 John Wiley & Sons, Ltd.
The use of the comprehensive International Classification of Functioning, Disability and Health Core Set for low back pain in clinical practice: a reliability study
Authors: Hilfiker Roger , Obrist Seraina , Christen Gregor , Lorenz Tobias , Cieza Alarcos
Published: February 2009

Background and Purpose. The comprehensive International Classification of Functioning, Disability and Health (ICF) Core Set for low back pain (LBP) can be used to describe functioning and the influence of the environment of patients with LBP with a selection of 78 categories, from the ICF components ‘body functions’, ‘body structures’, ‘activities and participation’ and ‘environmental factors’. The reliability of the qualifiers' scale of the ICF Core Set for LBP has not yet been studied. Methods. Reliability study was conducted in three study centres in the German‐speaking part of Switzerland. In the first step, two physiotherapists independently assessed 31 patients with LBP with the original qualifier scale of the 78 ICF categories from the comprehensive ICF Core Set for LBP. After the first 31 patients, inter‐rater reliability was assessed and the response options were reduced based on a Rasch analysis. The second sample (n = 30) was assessed by the physiotherapists with the modified qualifier scale and inter‐rater reliability was calculated again. Results. The percentage agreement for the ICF categories ranged from 19% to 87%, mean 44% (nominal kappa from −0.73 to 0.54, median 0.22; weighted kappa −0.2 to 0.69, median 0.38) in the first round with the original qualifier scale. In the second round with the reduced response options, the percentage agreement ranged from 23% to 90%, mean 49% (nominal kappa from −0.15 to 0.71, median 0.24; weighted kappa −0.16 to 0.81, median 0.25). The overall percentage agreement was 44% in the first round and 49% with the reduced response categories. The overall kappa value in the first round was 0.29 and in the second round 0.32. There was a small but statistically significant improvement in the agreement. Conclusion. The low‐to‐moderate reliability found in this study requires an improved operationalization (e.g. the definition and description of each response category) and improved instructions for the ICF Core Set for LBP. Copyright © 2009 John Wiley & Sons, Ltd.
Quantum dynamics of a discontinuously kicked charged particle in harmonic, symmetric double, or triple wells
Authors: Ghosh S. , Bhattacharyya S. P.
Published: February 2009

The quantum dynamics of a charged particle in a harmonic trap in the presence of discontinuous reversals of a homogeneous or an inhomogeneous electric field is studied. The dynamics reveals classically expected patterns in harmonic wells. In a symmetric double‐well potential, the discontinuously switched low intensity homogeneous electric field does not appear to assist tunneling, whereas an inhomogeneous electric field is found to assist the process. Resonance like enhancement is noticed at a critical reversal frequency. Dynamics in a triple well is also analyzed under similar conditions. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Improvements in the generalized hybrid orbital method
Authors: Eckard Simon , Exner Thomas E.
Published: February 2009

In a previous paper, we described the adaptation of the generalized hybrid orbital (GHO) method for the use in fragment based quantum chemical approaches for large molecules like the field‐adapted adjustable density matrix assembler (FA‐ADMA). It soon became evident that the limitations of the available implementation strongly restrict its use. Therefore, in the article presented here, we describe new developments to circumvent these limitations. These include new construction algorithms of the GHO hybrid orbitals for sp3‐ as well as sp2‐hybridized carbon and nitrogen, different distributions of electrons in the auxiliary orbitals, and the separation from the CHARMM program, which was needed to provide partial charges and bonding information. The results demonstrate an excellent improvement in accuracy of the obtained electron densities compared to capping hydrogen atoms. Additionally, the calculation of gradients opens the possibility to use FA‐ADMA for geometry optimization of large molecules. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Periodic DFT investigation on the structure and properties of TNAD crystal
Authors: Qiu Ling , Lin Jianguo , Ju Xuehai , Yang Min , Luo Shineng , Cao Guoxian
Published: February 2009

Density function theory calculations were performed at the GGA/PW91, GGA/PBE, and LDA/CA‐PZ levels to study the structures and properties of the crystalline TNAD (trans‐1,4,5,8‐tetranitrotetraazadecalin). The relaxed crystal structure compares well with the experimental data. Analysis on the band structures shows that the frontier energy bands are generally quite flat, and the energy gap between the highest occupied crystal orbital and the lowest unoccupied crystal orbital is about 3.4 eV, indicating that the crystal is an electrical insulator. All the atoms of TNAD make up both the lower and the higher energy bands. The projection of density of state demonstrates that the NNO2 bond is the most reactive region of the material. The lattice energy is predicted to be −155.13 kJ/mol at the LDA/CA‐PZ level, consistent with the previous studies, whereas it is underestimated by the GGA/PW91 (−70.41 kJ/mol) and GGA/PBE (−74.33 kJ/mol). The optical properties under ambient condition were investigated, including dielectric function, absorption coefficient, and reflectivity. The calculated absorption spectra show a number of absorption peaks in the fundamental absorption region, which are believed to be associated with different exciton states. And the reflectivity spectra are mainly composed of four peak structures, where the magnitude changes in the order of GGA/PBE < GGA/PW91 < LDA/CA‐PZ on the whole. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
High‐spin states in tetrahedral X4 clusters (X = H, Li, Na, K)
Authors: Monari Antonio , Pitarch‐Ruiz Jose , Bendazzoli Gian Luigi , Evangelisti Stefano , Sanchez‐Marin Jose
Published: February 2009

The high‐spin electronic states for lithium, sodium, and potassium four‐atom clusters were studied. In particular, we performed coupled cluster geometry optimization of the quintet state in tetrahedral geometry. The quintet state of these systems is characterized by having all the valence electron unpaired, giving rise to the so‐called no‐pair bonding. Single‐point full configuration interaction computations on the equilibrium geometries for the various clusters are also presented. The analysis of the valence orbitals in a localized representation confirms the importance of the p atomic orbitals to explain this unusual type of bond. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Quantum chemical investigation of lanthanum doping effects in tetragonal and rhombohedral PZT materials
Authors: Stashans Arvids , Maldonado Frank
Published: February 2009

Structural and electronic properties of lead–zirconate–titanate (PZT) materials doped with a lanthanum (La) impurity are studied using a quantum‐chemical approach based on the Hartree–Fock theory. Performed geometry optimization in the defective crystals shows that the atomic movements are predominantly outward with respect to the impurity position. It is found that the La impurity enhances a covalent character in the chemical bonding between the Ti and O atoms, as well as the Zr and O atoms situated in the neighborhood of the defect despite the fact that the La‐O interaction remains purely ionic. The occurrence of local energy levels within the band gap of the material is analyzed in light of the available experimental data on La concentration influence upon dielectric and piezoelectric properties in these crystals. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Structural, electronic, and optical properties of phenol‐pyridyl boron complexes for light‐emitting diodes
Authors: Zou Lu‐Yi , Ren Ai‐Min , Feng Ji‐Kang , Ran Xue‐Qin , Liu Yan‐Ling , Sun Chia‐Chung
Published: February 2009

The coordination chemistry of polydentate chelating ligands that contain mixed pyridinephenol donor sets has been a sought‐after target of study and is a possible extension to the chemistry of polypyridines. In this article, seven compounds, which are the four‐coordinate boron complexes containing the mixed phenol‐pyridyl group, have been studied by theoretical calculation. They can function as charge transport materials and emitters, with high efficiency and stability. To reveal the relationship between the structures and properties of these bifunctional or multifunctional electroluminescent materials, the ground and excited state geometries were optimized at the B3LYP/6‐31G(d), HF/6‐31G(d), and CIS/6‐31G(d) levels, respectively. The ionization potentials (IPs) and electron affinities (EAs) were computed. The mobilities of hole and electron in these compounds were studied computationally based on the Marcus electron transfer theory. The lowest excitation energies, and the maximum absorption and emission wavelengths of these compounds were calculated by time‐dependent density functional theory method. As a result of these calculations, the values of HOMO, LUMO, energy gaps, IPs, EAs, and the balance between the hole‐ and electron‐transfer are greatly improved with the substitution of carbazole in compound 6. The calculated emission spectra of the seven studied molecules can almost cover the full UV‐vis range (from 447.4 to 649.3 nm). Also, the Stokes shifts are unexpectedly large, ranging from 139.4 to 335.1 nm. This will result in the relatively long fluorescence lifetimes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Fish assemblage response to rehabilitation of a sand‐slugged lowland river
Authors: Howson T. J. , Robson B. J. , Mitchell B. D.
Published: February 2009

The impact of excessive sediment supply on river channels has been described in many areas of the world. Sediment deposition disturbance alters habitat structure by decreasing channel depth, changing substrate composition and burying woody debris. River rehabilitation is occurring worldwide, but information is scant on fish assemblage responses to rehabilitation in sediment‐disturbed lowland rivers. Sediment removal and large woody debris (LWD) replacement were used to experimentally rehabilitate habitat along a 1500 m stretch of the Glenelg River in western Victoria, Australia. Using an asymmetrical before‐after control‐impact (BACI) design, fish were captured before and after the reach was rehabilitated, from two control reaches and from a ‘higher quality’ reference reach. After two years post‐rehabilitation monitoring, the fish assemblage at the rehabilitated reach did not differ from control reaches. Temporal changes in taxa richness and the abundance of Philypnodon grandiceps, Nannoperca spp. and three angling taxa occurred after rehabilitation (winter 2003) compared with the before period (winter 2002), but these effects did not differ between rehabilitated and control locations. Highest taxa richness and abundances occurred at the reference location. High salinity coincided with the timing of rehabilitation works, associated with low river discharges due to drought. The negative effects of other large‐scale disturbances may have impaired the effectiveness of reach‐scale rehabilitation or the effects of rehabilitation may take longer than two years to develop in a lowland river subjected to multiple environmental disturbances. Copyright © 2009 John Wiley & Sons, Ltd.
Ecological effects of re‐introduction of salmonid spawning gravel in lowland Danish streams
Authors: Pedersen Morten Lauge , Kristensen Esben Astrup , Kronvang Brian , Thodsen Hans
Published: February 2009

During the past centuries natural spawning gravel was removed during the regulation of many streams in the Northern Hemisphere and wild fish stocks subsequently suffered due to this severe habitat degradation. To improve spawning conditions, projects involving reintroduction of spawning gravel have recently been conducted in many streams and rivers. However, systematic monitoring of these spawning gravel restoration projects is limited.

The overall aim of this paper was to evaluate gravel reintroduction as a long‐term salmonid rehabilitation method in 32 lowland streams. Displacement of gravel and abundance of original gravel was assessed on each site along with spawning activity and density of fry. In three streams, Gels Å, Stensbæk and Ryds Å, intensive studies of spawning activity, nursery habitat development and densities of trout fry and young‐of‐the‐year (YOY), were performed the following year, including both restored reaches and upstream control reaches.

Downstream displacement of gravel was most common at sites where gravel was reintroduced without further improvement, although these sites exhibited the highest density of YOY brown trout (Salmo trutta), evidencing that the remaining gravel is still functional. The intensive study of three streams showed that spawning was enhanced by the introduction of spawning gravel at the restored sites compared to control sites and that habitat quality generally were improved. Our results also suggest complex interactions exist between spawning activity, migrating trout and the emergence and survival of fry and YOY trout and the habitat conditions provided in regulated lowland Danish streams.

Our results clearly indicate that reintroduction of spawning gravel to restore fish populations in river systems warrants consideration of the differences in habitat quality that may occur among the reaches within a river system. Furthermore, spawning and nursery habitats should be present in all reaches to enhance survival of trout on re‐instated gravel. To increase our knowledge of spawning gravel restoration systematic monitoring and assessment out of projects are required following project implementation. Copyright © 2009 John Wiley & Sons, Ltd.
When is a key establishment protocol correct?
Authors: Dong Ling , Chen Kefei , Lai Xuejia , Wen Mi
Published: February 2009

This paper presents sufficient and necessary conditions to guarantee the security of a Key Establishment (KE) protocol based on our formalism of the belief multisets. The formalism is used to express the security of a KE protocol and to reason about beliefs in the protocol. We observe that a freshness identifier such as a nonce may not be fresh for a legitimate party in a particular protocol run, hence we distinguish a trusted freshness identifier from the commonly used freshness identifier in the sense of a participant's beliefs about the security. A central ingredient in our approach is that all the beliefs should be established on the basis of a trusted freshness identifier. The reasoning results of our approach, comparing with the security conditions, can either establish the correctness of a KE protocol when the protocol is in fact correct, or identify the absence of the security properties, which leads to the structure to construct attacks directly. Two examples, the Kerberos pair‐key agreement approach in distributed sensor networks and the Needham—Schroeder public key protocol, are given to show the usability and the efficiency of our approach. Copyright © 2009 John Wiley & Sons, Ltd.
Evaluation of uncertainties in X‐ray photoelectron spectroscopy intensities associated with different methods and procedures for background subtraction. I. Spectra for monochromatic Al X‐ray
Authors: Powell C. J. , Conny J. M.
Published: February 2009

We report uncertainties in X‐ray photoelectron spectroscopy (XPS) intensities arising from commonly used methods and procedures for subtraction of the spectral background. These uncertainties were determined from a comparison of XPS intensities reported by volunteer analysts from 28 institutions and the corresponding intensities expected for a set of simulated XPS spectra. We analyzed peak intensities from 32 sets of data for a group of 12 spectra that had been simulated for a monochromated Al Kα source. Each reported intensity was compared with an expected intensity for the particular integration limits chosen by each analyst and known from the simulation design. We present ratios of the reported intensities to the expected intensities for the background‐subtraction methods chosen by the analysts. These ratios were close to unity in most cases, as expected, but deviations were found in the results from some analysts, particularly if the main peak was asymmetrical or if shakeup was present. We showed that better results for the Shirley, Tougaard, and linear backgrounds were obtained when analysts determined peak intensities over certain energy ranges or integration limits. We then were able to recommend integration limits that should be a useful guide in the determination of peak intensities for other XPS spectra. The use of relatively narrow integration limits with the Shirley and linear backgrounds, however, will lead to measures of peak intensities that are less than the total intensities. Although these measures may be satisfactory for some quantitative analyses, errors in quantitative XPS analyses can occur if there are changes in XPS lineshapes or shakeup fractions with change of chemical state. The use of curve‐fitting equations to fit an entire spectrum will generally exclude the shakeup contribution to the intensity of the main peak, and no account will be taken of any variation in the shakeup fraction with change of chemical state. Published in 2009 by John Wiley & Sons, Ltd.

Certain commercial products are identified to specify the formats in which the test spectra were distributed and the software with which the test spectra were analyzed by participants. This identification does not imply that the products are endorsed or recommended by the National Institute of Standards and Technology, or that they are necessarily the most suitable for the purposes described.
Markov mobility model and registration area optimization in cellular networks
Authors: Liu Z. , Almhana J. , McGorman R.
Published: February 2009

In cellular communication systems, in order for a network to keep track of inactive mobile stations (MSs), each inactive MS has to update its location from time to time, called location registration. To lighten the task of tracking inactive MSs, the network divides its cells into groups, called location areas (LAs) and tracks inactive MSs at the LA level: an inactive MS sends a registration message to the network to update its location only when it travels to a new LA. Obviously, the performance of a location area design depends on network traffic and the mobility of MSs. In the paper, we propose a general Markov mobility model for MSs in cellular networks, provide a procedure to automatically estimate the system parameters according to the network traffic, derive the performance of LA design, and provide a clustering algorithm to optimize LA designs. A numerical example is provided to show the effectiveness of the proposed procedures. Copyright © 2009 John Wiley & Sons, Ltd.
Brain Metastases in Colorectal Cancers
Authors: Tan Wah‐Siew , Ho Kok‐Sun , Eu Kong‐Weng
Published: February 2009

Background

Although colorectal cancer is the most common cancer in Singapore, brain metastases associated with colorectal primaries are quite rare, with reported incidences ranging from less than 1% to 4%. This is a review of the incidence, presentation, and prognosis of brain secondaries from colorectal primaries in our institution.

Methods

From a prospectively collected database, 4378 patients underwent surgery for colorectal cancers between 1995 and 2003. Patients who developed brain metastases were identified and their records reviewed retrospectively.

Results

Twenty‐seven patients who developed brain metastases were identified, for an incidence of 0.62%. Seventy‐one percent of the patients had a tumor in the rectum or sigmoid; 92.6% of patients had metachronous brain secondaries. The median interval between surgery for the primary tumor and the discovery of a brain secondary was 27.5 months. The lung was the most common site of concurrent metastatic disease, with the discovery of a brain secondary a median of 9.7 months after diagnosis of the lung lesion. All patients were symptomatic. The majority of the patients received nonsurgical treatment for the brain lesion. Median survival after diagnosis of brain secondaries was 2.4 months.

Conclusions

The poor survival of the patients in our series could be due to late diagnosis. It may be recommended that a brain scan be performed to screen for a brain secondary when lung and/or liver metastases are discovered, especially in a patient with a left‐sided cancer. This may lead to earlier diagnosis, amenability to surgical treatment, and improved survival and quality of life.
Phenylalanine tolerance in three phenylketonuric women pregnant with fetuses of different genetic PKU status
Authors: Kohlschütter B. , Ellerbrok M. , Merkel M. , Tchirikov M. , Zschocke J. , Santer R. , Ullrich K.
Published: February 2009

Pregnancy management in phenylketonuric women includes continuous dietary control starting before conception, aiming to maintain blood phenylalanine concentrations in a desirable range, irrespective of the fetal genetic PKU status. While the maternal phenylalanine hydroxylase (PAH) genotype will influence metabolic control, an effect of the fetal genetic PKU status on maternal metabolic control during pregnancy has not been described. We monitored three pregnancies of women with classical PKU by dietary protocols of daily phenylalanine intake, phenylalanine blood concentrations, and obstetric care. Patients 1 and 2 carried a heterozygous (not PKU‐affected) fetus, while patient 3 was pregnant with a PKU‐affected fetus (PAH p.R408W and p.R408W). The expected increase in phenylalanine tolerance during the course of pregnancy was observed in patients 1 and 2 in whom phenylalanine intake could be steadily increased from 400 to 1700 mg/day while phenylalanine blood concentrations remained in the desired range. Gain of body weight was 13.0 and 17.7 kg, respectively. In patient 3, the phenylalanine tolerance did not rise above 600 mg/day, and phenylalanine blood concentrations were above the desired range on several occasions. Caloric intake was therefore encouraged, which led to a weight gain of 20.0 kg. The course of pregnancy was otherwise normal in all three cases, and infants with normal birth weight and head circumference were born. The different phenylalanine tolerance in pregnancies with PKU‐affected and non‐affected fetuses suggests that PAH genotype and metabolic situation of the fetus influence maternal metabolic control. A phenylalanine tolerance remaining low in the third trimester of pregnancy may indicate fetal PKU.
Intercepting pelvic cancer in the distal fallopian tube: Theories and realities
Authors: Crum Christopher P.
Published: February 2009

The pathogenesis of high‐grade serous carcinoma of the ovary has come into sharper focus as closer attention has been paid to the earlier phases of this disease. The study of patients with BRCA mutation has been of particular value, in as much as the examination of prophylactic salpingo‐oophorectomies will reveal an early cancer in approximately 5% of individuals. Recently studies have shown that about 80% of these early carcinomas originate in the distal fallopian tube. This review summarizes the recent data supporting the distal fallopian tube as an important site for serous carcinogenesis, stressing both the presence of a novel precursor (the p53 signature) and the application of this model to all women irrespective of BRCA status. The challenges and unmet needs unmasked by this paradigm shift in ovarian cancer research are discussed.
Molecular characterization of apocrine carcinoma of the breast: Validation of an apocrine protein signature in a well‐defined cohort
Authors: Celis Julio E. , Cabezón Teresa , Moreira José M.A. , Gromov Pavel , Gromova Irina , Timmermans-Wielenga Vera , Iwase Takuji , Akiyama Futoshi , Honma Naoko , Rank Fritz
Published: February 2009

Invasive apocrine carcinomas (IACs), as defined by morphological features, correspond to 0.3–4% of all invasive ductal carcinomas (IDC), and despite the fact that they are histologically distinct from other breast lesions there are currently no standard molecular criteria available for their diagnosis and no unequivocal information as to their prognosis. In an effort to address these concerns we have been using protein expression profiling technologies in combination with mass spectrometry and immunohistochemistry (IHC) to discover specific biomarkers that could allow us to molecularly characterize these lesions as well as to dissect some of the steps in the processes underlying breast apocrine metaplasia and development of precancerous apocrine lesions. Establishing these apocrine‐specific markers as best practice for the routine pathology evaluation of breast cancer, however, will require their validation in large cohorts of patients. Towards this goal we have composed a panel of antibodies against components of an apocrine protein signature that includes probes against the apocrine‐specific markers 15‐prostaglandin dehydrogenase (15‐PGDH), and acyl‐CoA synthetase medium‐chain family member 1 (ACSM1), in addition to a set of categorizing markers that are consistently expressed (AR, CD24) or not expressed (ERα, PgR, Bcl‐2, and GATA‐3) by apocrine metaplasia in benign breast lesions and apocrine sweat glands. This panel was used to analyze a well‐defined cohort consisting of 14 apocrine ductal carcinoma in situ (ADCIS), and 33 IACs diagnosed at the Cancer Institute Hospital, Tokyo between 1997 and 2001. Samples were originally classified on the basis of cellular morphology with all cases having more than 90% of the tumour cells exhibiting cytological features typical of apocrine cells. Using the expression of 15‐PGDH and/or ACSM1 as the main criterion, but taking into account the expression of other markers, we were able to identify unambiguously 13 out of 14 ADCIS (92.9%) and 20 out of 33 (60.6%) IAC samples, respectively, as being of apocrine origin. Our results demonstrate that IACs correspond to a distinct, even if heterogeneous, molecular subgroup of breast carcinomas that can be readily identified in an unbiased way using a combination of markers that recapitulate the phenotype of apocrine sweat glands (15‐PGDH+, ACSM1+, AR+, CD24+, ERα−, PgR−, Bcl‐2−, and GATA‐3−). These results pave the way for addressing issues such as prognosis of IACs, patient stratification for targeted therapeutics, as well as research strategies for identifying novel therapeutic targets for developing new cancer therapies.
Neurotensin signaling induces intracellular alkalinization and interleukin‐8 expression in human pancreatic cancer cells
Authors: Olszewski Ulrike , Hamilton Gerhard
Published: February 2009

Pancreatic adenocarcinomas express neurotensin receptors in up to 90% of cases, however, their role in tumor biology and as a drug target is not clear. In the present study, a stable neurotensin (NT) analog induced intracellular calcium release and intracellular alkalinization in BxPC‐3 and PANC‐1 pancreatic cancer cells that was abolished by inhibitors of NT receptor (NTR) and sodium–proton exchanger 1 (NHE1), amiloride and SR 142948, respectively. Activation of NHE1 involved increased phosphorylation of dimethylfumarate‐sensitive mitogen‐ and stress‐activated kinase 1/2 (MSK1/2). NTR signaling appears to promote a metastatic phenotype in pancreatic cancer cells by induction of localized extracellular acidification in normoxic cells, preceeding acidosis induced by hypoxia and switch to glycolysis in addition to increased expression of interleukin‐8 (IL‐8).
Cohomology for Bicomodules. Separable and Maschke functors
Authors: El Kaoutit L. , Vercruysse J.
Published: February 2009

We introduce the category of bicomodules for a comonad on a Grothendieck category whose underlying functor is right exact and preserves direct sums. We characterize comonads with a separable forgetful functor by means of cohomology groups using cointegrations into bicomodules. We present two applications: the characterization of coseparable corings stated in [14], and the characterization of coseparable coalgebra coextensions stated in [19].