bluuebunny/crossref_metadata_2025 huggingface dataset:
Objective analyses of annual, seasonal, and monthly temperature and salinity for the World Ocean on a 0.25° grid
Authors: Boyer Timothy , Levitus Sydney , Garcia Hernan , Locarnini Ricardo A. , Stephens Cathy , Antonov John
Published: June 2005

Objectively analysed climatological mean fields of temperature and salinity have been calculated on a 0.25° grid for the World Ocean for the annual, seasonal, and monthly compositing periods using data from the World Ocean Database 2001. The annual and seasonal fields are calculated at standard levels from the surface to 5500 m. The monthly fields are calculated at standard levels from the surface to 1500 m. In comparison with similarly computed climatologies calculated on a 1° grid, ocean circulation features, such as the Gulf of Mexico Loop Current, are more clearly represented. The new 0.25° climatologies preserve most of the spatial resolution of earlier 0.25° temperature and salinity climatologies, while reducing noise by additional smoothing in horizontal space (geographically at each depth), vertically (along depth at each grid), as well as in time (Fourier filtering). Copyright © 2005 Royal Meteorological Society
Climatology, variability and extrema of ocean waves: the Web‐based KNMI/ERA‐40 wave atlas
Authors: Sterl Andreas , Caires Sofia
Published: June 2005

The European Centre for Medium‐Range Weather Forecasts (ECMWF) has recently finished ERA‐40, a reanalysis covering the period September 1957 to August 2002. One of the products of ERA‐40 consists of six‐hourly global fields of wave parameters, like significant wave height and wave period. These data have been generated with the centre's WAM wave model. From these results we have derived climatologies of important wave parameters, including significant wave height, mean wave period, and extreme significant wave heights. Particular emphasis is on the variability of these parameters, both in space and time. Besides being important for scientists studying climate change, these results are also important for engineers who have to design maritime constructions. This paper describes the ERA‐40 data and gives an overview of the results derived. The results are available on a global 1.5° × 1.5° grid. They are accessible from the Web‐based KNMI/ERA‐40 wave atlas at http://www.knmi.nl/waveatlas. Copyright © 2005 Royal Meteorological Society
An overview of the airflow distortion at anemometer sites on ships
Authors: Moat Bengamin I. , Yelland Margaret J. , Pascal Robin W. , Molland Anthony F.
Published: June 2005

Wind speed measurements obtained from ship‐mounted anemometers are biased by the presence of the ship itself distorting the flow of air to the anemometer. Recent studies have used numerical models to simulate the flow around very detailed representations of individual research ships in order to quantify the effects of flow distortion at the anemometer locations. Such anemometers are generally in well‐exposed positions, typically on a mast in the bows of the ship. In contrast, very little is known about the possible effects of airflow distortion on the wind speed measurements from fixed anemometers on Voluntary Observing Ships (VOS). This is because (1) the several thousand or so merchant vessels vary significantly in shape and size and it would be impractical to study each individual ship, and (2) the anemometer location is not usually known.

This paper describes initial results from a study of flow distortion over ‘typical’ tankers and bulk carriers. A method to describe the shapes of these VOS and container ships is presented. The influence of distortion on the flow above the bridges of VOS is shown to be significant, with possible biases in the measured wind speed of between +11% and −100%, depending on the anemometer location. Recommendations for the siting of anemometers are made. Copyright © 2005 Royal Meteorological Society
The effect of instrument exposure on marine air temperatures: an assessment using VOSClim Data
Authors: Berry David I. , Kent Elizabeth C.
Published: June 2005

Observations of marine air temperature (MAT) by Voluntary Observing Ships (VOS) are known to contain significant biases due to solar heating of the sensor environment. MAT and humidity observations are usually made using wet‐ and dry‐bulb thermometers housed in Stevenson screens, or with psychrometers. These instruments are typically mounted in the bridge wings or on the wheel‐house top. If not sited carefully then the instruments can be poorly exposed to the undisturbed environmental conditions and have inadequate ventilation, leading to biased observations of both MAT and humidity.

In this paper we use observations collected as part of the VOS Climate (VOSClim) project to investigate the relationship between instrument exposure and heating errors. The heating errors are estimated as the difference between the observed MAT and the collocated output of a numerical weather prediction model. The instrument exposures are assessed from photographs of the instruments. Currently, photographs of the instruments and sufficient observations exist for 17 VOSClim ships.

Two methods of assessing the instrument exposure using the observations are presented. The first method is based on the skewness of the distribution of estimated heating errors for individual ships. The second method is based on a correction developed to correct the heating errors and uses the ratio of the heating to cooling terms in the correction. When ships are ranked both on the skewness and on the ratio of the heating to cooling terms, there is a statistically significant correspondence between the rankings and the visual assessments of instrument exposure. The skewness of the distribution of estimated errors in MAT is proposed as a simple indicator of instrument exposure. Copyright © 2005 Royal Meteorological Society
Abrupt climatic changes and an unstable transition into a late Holocene Thermal Decline: a multiproxy lacustrine record from southern Sweden
Authors: Jessen Catherine A. , Rundgren Mats , Björck Svante , Hammarlund Dan
Published: June 2005

The transition from a middle Holocene relatively warm and stable climate to a cooler and unstable late Holocene climate is reconstructed using sediments from Lake Igelsjön, south‐ central Sweden. This multiproxy study illustrates local, regional and global scale responses to climatic change by focusing on a previously identified abrupt hydrological shift to cooler and/or wetter conditions around 4000 cal. yr BP. The results suggest that between ca. 4600 and ca. 3400 cal. yr BP, the environment around and within the lake responded in two major, well‐defined steps: the first between 4450 and 4350 cal. yr BP and the second between 4000 and 3800 cal. yr BP. A series of rapid fluctuations of short duration were superimposed on the general cooling trend, with the most severe aquatic response peaking at ca. 3800 cal. yr BP. Pollen percentage and influx values show forest composition and pollen productivity changes and a distinct decline in total and Corylus pollen influx in the period of 4000–3500 cal. yr BP. Stomatal‐based reconstruction of atmospheric CO2 concentration produced a tenuous decrease with a minimum between 3650 and 3500 cal. yr BP. Copyright © 2005 John Wiley & Sons, Ltd.
Late Quaternary history of the coastal Wahiba Sands, Sultanate of Oman
Authors: Preusser Frank , Radies Dirk , Driehorst Frauke , Matter Albert
Published: June 2005

Continental sediments and geomorphological features of the coastal Wahiba Sands, Sultanate of Oman, reflect environmental variability in southeastern Arabia during the late Quaternary. Weakly cemented dune sands, interdune deposits and coastal sediments were dated by luminescence methods to establish an absolute chronology of changes in sedimentary dynamics. The dating results confirm previous assumptions that during times of low global sea level sand was transported by southerly winds from the exposed shelf onto the Arabian Peninsula. Two prominent phases of sand accumulation in the coastal area took place just before and after the last glacial maximum (LGM). A final significant period of dune consolidation is recognised during the early Holocene. However, no major consolidation of dunes appears to have occurred during the LGM and the Younger Dryas. In the northern part of the Wahiba Sands, these two periods are characterised by substantial sand deposition. This discrepancy is explained by the lack of conservation potential for dunes in the coastal area, probably caused by a low groundwater table due to low sea level and decreased precipitation. While the times of aeolian activity reflect arid to hyper‐arid conditions, lacustrine and pedogenically altered interdune deposits indicate wetter conditions than today caused by increased monsoonal circulation during the Holocene climatic optimum. Copyright © 2005 John Wiley & Sons, Ltd.
Late Glacial fluvial response of the Niers‐Rhine (western Germany) to climate and vegetation change
Authors: Kasse C. , Hoek W. Z. , Bohncke S. J. P. , Konert M. , Weijers J. W. H. , Cassee M. L. , Van Der Zee R. M.
Published: June 2005

The Niers valley was part of the Rhine system that came into existence during the maximum Saalian glaciation and was abandoned at the end of the Weichselian. The aim of the study was to explain the Late Pleniglacial and Late Glacial fluvial dynamics and to explore the external forcing factors: climate change, tectonics and sea level.

The sedimentary units have been investigated by large‐scale coring transects and detailed cross‐sections over abandoned channels. The temporal fluvial development has been reconstructed by means of geomorphological relationships, pollen analysis and 14C dating.

The Niers‐Rhine experienced a channel pattern change from braided, via a transformational phase, to meandering in the early Late Glacial. This change in fluvial style is explained by climate amelioration at the Late Pleniglacial to Late Glacial transition (at ca. 12.5 k 14C yr BP) and climate‐related hydrological, lithological and vegetation changes. A delayed fluvial response of ca. 400 14C yr (transitional phase) was established. The channel transformations are not related to tectonic effects and sea‐level changes. Successive river systems have similar gradients of ca. 35–40 cm km−1.

A meandering river system dominated the Allerød and Younger Dryas periods. The threshold towards braiding was not crossed during the Younger Dryas, but increased aeolian activity has been observed on the Younger Dryas point bars. The final abandonment of the Niers‐Rhine was dated shortly after the Younger Dryas to Holocene transition.

Traces of Laacher See pumice have been found in the Niers valley, indicating that the Niers‐Rhine was still in use during the Younger Dryas. Copyright © 2005 John Wiley & Sons, Ltd.
Rhizocarpon calibration curve for the Aoraki/Mount Cook area of New Zealand
Authors: Lowell Thomas V. , Schoenenberger Katherine , Deddens James A. , Denton George H. , Smith Colby , Black Jessica , Hendy Chris H.
Published: June 2005

Development of Rhizocarpon growth curve from the Aoraki/Mount Cook area of New Zealand provides a means to assess Little Ice Age glacier behaviour and suggests approaches that have wider application. Employing a sampling strategy based on large populations affords the opportunity to assess which of various metrics (e.g. single largest, average of five largest, mean of an entire population) best characterise Rhizocarpon growth patterns. The 98% quantile from each population fitted with a quadric curve forms a reliable representation of the growth pattern. Since this metric does not depend on the original sample size, comparisons are valid where sample strategy must be adapted to local situations or where the original sample size differs. For the Aoraki/Mount Cook area a surface 100 years old will have a 98% quantile lichen diameter of 34.3 mm, whereas a 200‐year‐old surface will have a lichen diameter of 73.7 mm. In the Southern Alps, constraints from the age range of calibration points, the flattening of the quadric calibration curve and ecological factors limit the useful age range to approximately 250 years. Copyright © 2005 John Wiley & Sons, Ltd.
Resistant starch production from mango starch using a single‐screw extruder
Authors: Agustiniano‐Osornio July C , González‐Soto Rosalía A , Flores‐Huicochea Emmanuel , Manrique‐Quevedo Nancy , Sánchez‐Hernández Laura , Bello‐Pérez Luis A
Published: June 2005

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg−1) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg−1), but low WAI values (70–77 g kg−1) were obtained at moisture contents between 200 and 300 g kg−1 and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg−1), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg−1), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry
Antifungal property of the essential oils and their constituents from Cinnamomum osmophloeum leaf against tree pathogenic fungi
Authors: Lee Han‐Chung , Cheng Sen‐Sung , Chang Shang‐Tzen
Published: June 2005

This study compares the chemical constituents of leaf essential oils from various geographical provenances of Cinnamomum osmophloeum and investigates their antifungal activities against six tree pathogenic fungi. According to GC‐MS and cluster analyses, the leaf essential oils obtained from different geographical provenances and their relative contents were classified into six chemotypes: cinnamaldehyde type, cinnamaldehyde–cinnamyl acetate type, cinnamyl acetate type, linalool type, camphor type, and mixed type. Results from the antifungal tests show that the leaf essential oils of cinnamaldehyde type and cinnamaldehyde–cinnamyl acetate type have excellent inhibitory effect against Rhizoctonia solani, Collectotrichum gloeosporioides, Ganoderma australe and Fusarium solani. Furthermore, among the fourteen constituents of C osmophloeum leaf essential oils, Z‐cinnamaldehyde, eugenol, geraniol and citral display the best antifungal properties. Comparisons of the antifungal properties of Z‐cinnamaldehyde congeners reveal that Z‐cinnamaldehyde exhibits the best antifungal property of this group. Copyright © 2005 Society of Chemical Industry
Fate of aflatoxin M1 in cheese whey processing
Authors: Mendonça Carla , Venâncio Armando
Published: June 2005

Aflatoxin M1 (AFM1) is an important mycotoxin frequently found in milk and in dairy products. It is a minor metabolic product of Aspergillus flavus and A parasiticus. However, it occurs in dairy products as a metabolite formed in cows from aflatoxin B1 contained in animal feeds. In cheese production, AFM1 distributes between curd and whey, being present in products derived from cheese whey processing. In this study, cheese whey from dairy processing was artificially contaminated with the mycotoxin at about 0.1 µg l−1. Ultra‐filtration experiments of whey were carried out in order to determinate AFM1 distribution between retentate (protein‐rich fraction) and permeate (lactose‐rich fraction). Recoveries of AFM1 in retentate were 72.6–86.4% while, in permeate, recoveries were in the range 2.4–14.7%. Partition coefficients of AFM1, lactose and protein were calculated to determine whether there was an interaction between AFM1 and protein. In all experiments, AFM1 partition coefficient was lower than 1, whilst for lactose coefficients close to 1 were determined, showing an affinity of aflatoxin M1 to the protein‐rich fraction (retentate). Copyright © 2005 Society of Chemical Industry
Whey protein isolate coating and concentration effects on egg shelf life
Authors: Caner Cengiz
Published: June 2005

The influences of three different concentrations (6, 12 and 18%) of whey protein isolate (WPI) coatings on shelf‐life enhancements of the fresh egg quality (weight loss, pH, Haugh unit, yolk index and colors) and the shelf life were evaluated at room temperature. All coated eggs showed lower weight loss than uncoated eggs. Less weight loss (2.46 for 12% WPI and 2.38 for 18% WPI) was observed in WPI‐coated eggs. Haugh units (HU) indicated that coated eggs remained in grade ‘A’ during 3 weeks storage period, whereas uncoated (UC) changed from grade ‘A’ to ‘B’ after 1 week of storage. The HU and yolk‐index (YI) values of all WPI‐coated eggs were significantly higher than those of UC. Among the coated eggs, there were no significant differences in HU, but 12 and 18% WPI coated had higher YI than WPI 6% coated and UC. The albumen pH of the UC eggs was significantly higher than that of coated eggs. Yolk lightness (L*) and (b*); shell (a*) and (b*) of coated eggs were not different from UC after 4 weeks. Performance of WPI coatings depended on the concentration up to 12% but not between 12 and 18%. Results also indicated that WPI coatings served as protective barrier for shelf life of the eggs. Copyright © 2005 Society of Chemical Industry
Evaluation of saltgrass as a fodder crop for livestock
Authors: Bustan Amnon , Pasternak Dov , Pirogova Irina , Durikov Muhamet , Devries Tonny T , El‐Meccawi Shaher , Degen A Allan
Published: June 2005

Farmland salinization due to unsustainable agricultural practices has become a worldwide problem. Salt‐resistant forage crops, introduced at the primary stages of land reclamation, can provide fodder for livestock, thus adding economic benefit to the process. Saltgrass (Distichlis spicata), a wild halophytic grass species distributed in salt marshes in America, is occasionally grazed by livestock and wild animals. In attempts to domesticate this species, we evaluated and ranked the fodder potential of groups of accessions from several sites in North and South America. Ash content never exceeded 110 g kg−1, even when plants were grown with salty water. Crude protein content was variable and averaged 116 g kg−1 of DM. Mean yield of metabolizable energy was 6.30 and 5.61 kJ g−1 DM for sheep and goats, respectively. Organic matter digestibility (in vitro) was higher in sheep than in goats (506 g kg−1 and 478 g kg−1, respectively) for all saltgrass accessions. Differences in quality parameters were usually larger within than among groups of accession when sorted according to country of origin or ecosystem. Accessions from the South Atlantic coast of North America and from South America were superior in several parameters. South Atlantic coast accessions were relatively vigorous and were productive under saline conditions, as indicated by their relative growth rate (RGR) in small‐scale experiments. Six outstanding saltgrass accessions were chosen for further examination. The results of the present study indicate that saltgrass holds considerable promise for selection and suggest that efforts should continue to identify and characterize additional saltgrass ecotypes. Copyright © 2005 Society of Chemical Industry
Preparation and use of packed capillary columns in chromatographic and related techniques
Authors: Lanças Fernando M. , Rodrigues José C. , de S. Freitas Silvia
Published: June 2005

In this paper general considerations related to the various approaches and parameters influencing the preparation of highly efficient and stable capillary columns for use in liquid chromatography and related techniques are presented and the column production process is discussed in some detail. The different packing methods available for delivering a packing material into a capillary column are discussed from a practical viewpoint. Packing with a gas (dry packing), packing with a liquid solvent or a mixture of solvents (slurry packing), packing with supercritical carbon dioxide, electrokinetic packing, and sol‐gel packing technologies are introduced and discussed throughout the paper. Practical recommendations for obtaining highly efficient (high plate numbers) and stable capillary packed columns are also addressed and discussed.
Cover Picture: Macromol. Rapid Commun. 11/2005
Authors: Barriau Emilie , García Marcos Alejandra , Kautz Holger , Frey Holger
Published: June 2005

Cover: A convenient three‐step strategy leads to well‐defined linear hyperbranched amphiphilic polystyrene‐block‐polyglycerol block copolymers by hypergrafting. The polymers form ordered micellar structures in solution. The AFM image shows the core‐shell nanostructures obtained after deposition of the micelles on graphite. Further details can be found in the Communication by E. Barriau, A. García Marcos, H. Kautz, and H. Frey on page 862.
Epigenetic inactivation of CHFR in nasopharyngeal carcinoma through promoter methylation
Authors: Cheung Hiu Wing , Ching Yick‐Pang , Nicholls John M. , Ling Ming‐Tat , Wong Y.C. , Hui Nick , Cheung Annie , Tsao Sai Wah , Wang Qi , Yeun P.W. , Lo K.W. , Jin Dong‐Yan , Wang Xianghong
Published: June 2005

Chromosomal instability (CIN) is a cytogenetic hallmark of human cancers. Increasing evidence suggests that impairment of mitotic checkpoint is causally associated with CIN. CHFR is one of the mitotic checkpoint regulators and it delays chromosome condensation in response to mitotic stress. Epigenetic inactivation of CHFR through promoter CpG hypermethylation may lead to CIN and has been reported in several human cancers. In this study, we investigated the CHFR gene expression in a panel of nasopharyngeal carcinoma (NPC), prostate, ovarian, and breast cancer cell lines. We found that the expression of CHFR mRNA was significantly decreased or undetectable in all eight NPC cell lines as well as three human NPC xenografts, whereas non‐malignant nasopharyngeal cell lines and other cancer cell lines tested expressed CHFR at relatively high levels. Hypermethylation of CHFR promoter region was also strongly correlated with decreased CHFR expression in NPC cell lines and xenografts. Treatment with a methyltransferase inhibitor, 5‐aza‐2′‐deoxycytidine, led to restoration of CHFR expression in NPC cell lines. More importantly, hypermethylation of CHFR promoter region was detected in 61.1% (22 out of 36) of primary NPC tumors while it was absent in non‐malignant tissues. These findings suggest that downregulation of CHFR is a common event in NPC cells which may be due to hypermethylation of the gene promoter region. © 2005 Wiley‐Liss, Inc.
Generation of a unique strain of multiple intestinal neoplasia (Apc+/Min‐FCCC) mice with significantly increased numbers of colorectal adenomas
Authors: Cooper Harry S. , Chang Wen‐Chi L. , Coudry Renata , Gary Monique A. , Everley Lynette , Spittle Cynthia S. , Wang Hao , Litwin Sam , Clapper Margie L.
Published: June 2005

The relevance of the Apc+/Min mouse model in the study of human colorectal cancer remains uncertain due to the predominance of small intestinal adenomas and few, if any, colorectal adenomas. A new strain of Apc+/Min mice (Apc+/Min‐FCCC) with significantly greater numbers of colorectal adenomas has been generated and characterized. Male C57BL/6J—Apc+/Min mice (the Jackson Laboratory, Bar Harbor, ME) were crossed with wild‐type (Apc+/+) C57BL/6J females from an independent colony at this institution (offspring = Apc+/Min‐FCCC) and 233 animals were evaluated over 20 generations. In order to determine the contribution of genetics to the enhanced colorectal adenoma phenotype, breeding pairs (Apc+/Min male × wild type female C57BL/6J) were purchased from the Jackson Laboratory and offspring (Apc+/Min‐JAX) were maintained in our facility under identical conditions (n = 98). Animals were fed Purina Rodent chow (#5013) diet containing 5% fat. The entire intestinal tract was examined histopathologically in both strains. Both the Apc and Pla2g2a (candidate for Mom1) genes were sequenced and found to be identical for both the Apc+/Min‐FCCC and Apc+/Min‐JAX mouse strains. The multiplicity of colorectal adenomas in the Apc+/Min‐FCCC mice was much higher than reported in the literature and significantly greater than the multiplicity of colorectal adenomas in Apc+/Min‐JAX mice maintained in our facility (P = 0.01). Apc+/Min‐FCCC had a significantly greater incidence of rectal prolapse (P = 0.02) and small intestinal adenocarcinomes (P = 0.001), and multiplicity of small intestinal adenocarcinomas (P = 0.001) compared to Apc+/Min‐JAX mice. Male Apc+/Min‐FCCC mice had significantly greater numbers of colorectal adenomas compared to female Apc+/Min‐FCCC mice (P = 0.0002), as did male Apc+/Min‐JAX mice vs. female Apc+/Min‐JAX mice (P < 0.0001). These results allow us to conclude: (1) Apc+/Min‐FCCC mice are unique in that they develop significantly greater numbers of colorectal adenomas and small intestinal cancers, and a significantly greater incidence of small intestinal cancers and rectal prolapse than Apc+/Min‐JAX mice. (2) This study represents the first report of a significant gender difference in multiplicity of colorectal adenomas. (3) Differences between Apc+/Min‐FCCC and Apc+/Min‐JAX mice in currently undefined genetic modifiers may contribute to the enhanced colorectal phenotype. (4) The Apc+/Min‐FCCC strain is highly suited for the investigation of colorectal neoplastic disease and chemoprevention studies. © 2005 Wiley‐Liss, Inc.
Numerical modelling of chemical effects of magma solidification problems in porous rocks
Authors: Zhao Chongbin , Hobbs B. E. , Ord A. , Peng Shenglin , Mühlhaus H. B. , Liu Liangming
Published: June 2005

The solidification of intruded magma in porous rocks can result in the following two consequences: (1) the heat release due to the solidification of the interface between the rock and intruded magma and (2) the mass release of the volatile fluids in the region where the intruded magma is solidified into the rock. Traditionally, the intruded magma solidification problem is treated as a moving interface (i.e. the solidification interface between the rock and intruded magma) problem to consider these consequences in conventional numerical methods. This paper presents an alternative new approach to simulate thermal and chemical consequences/effects of magma intrusion in geological systems, which are composed of porous rocks. In the proposed new approach and algorithm, the original magma solidification problem with a moving boundary between the rock and intruded magma is transformed into a new problem without the moving boundary but with the proposed mass source and physically equivalent heat source. The major advantage in using the proposed equivalent algorithm is that a fixed mesh of finite elements with a variable integration time‐step can be employed to simulate the consequences and effects of the intruded magma solidification using the conventional finite element method. The correctness and usefulness of the proposed equivalent algorithm have been demonstrated by a benchmark magma solidification problem. Copyright © 2005 John Wiley & Sons, Ltd.
Experimental (FT‐ICR) and theoretical (DFT) estimation of the basic site preference for the bidentate molecule 2‐(β‐aminoethyl)‐pyridine: similarity with histamine
Authors: Raczyńska Ewa D. , Rudka Tomasz , Darowska Małgorzata , Dąbkowska Iwona , Gal Jean‐François , Maria Pierre‐Charles
Published: June 2005

The gas‐phase basicity of 2‐(β‐aminoethyl)‐pyridine (AEP)—an agonist of the histamine H1 receptor—containing two potential basic sites (the ring N‐aza and the chain N‐amino) was obtained from proton‐transfer equilibrium constant measurements using Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR). Comparison of the experimental gas‐phase basicity found for AEP with those reported for monobasic model compounds indicates that the ring N‐aza is the favoured site of protonation, as with histamine. The gas‐phase basicity of AEP is lower than that of histamine by only 1.3 kcal mol−1. DFT(B3LYP)/6–31G* calculations performed for AEP, histamine and their protonated forms confirm this interpretation. The energy barriers calculated at the DFT(B3LYP)/6–31G* level for internal transfer of the proton (ITP) between the ring N‐aza and the chain N‐amino in AEP and histamine are extremely low, and vanish when thermal corrections are applied to obtain the enthalpies or Gibbs energies of activation for the proton transfer. This indicates that the quantum‐chemical ITPs in AEP and histamine have a single‐well character, similar to that proposed for the previously studied dibasic nitrogen ligand, N1,N1‐dimethyl‐N2‐β‐(2‐pyridylethyl)‐formamidine, where two potential nitrogen basic sites (both nitrogen atoms in sp2 hybridization) are separated by the ethylene group. Enlarging the basis set to 6‐311G(2d,p) has no influence on this finding. A change of the basicity centre preference in AEP from the ring N‐aza to the chain N‐amino on going from the gas phase to aqueous solution was predicted using the polarizable continuum model applied to the DFT(B3LYP)/6–31G* optimized geometries of the N‐aza and N‐amino monoprotonated forms. This behaviour is similar to that observed for histamine. Copyright © 2005 John Wiley & Sons, Ltd.
Structural aspects of phase transition in pyrrole‐2,5‐dithioamide single crystals
Authors: Dobrzycki Lukasz , Zielinski Tomasz , Jurczak Janusz , Wozniak Krzysztof
Published: June 2005

The new pyrrole thioamide derivative 1H‐pyrrole‐2,5‐dithiocarboxylic acid bis(n‐butylamide) exists in two different phases with the first‐order phase transition at ∼195.8 K on heating up. We describe details of the lower and higher temperature phases and the nature of the phase transition. The high‐temperature phase is centrosymmetric, with the molecule having one statically disordered aliphatic chain, whereas the low‐temperature crystals are characterized by chiral P21 space group symmetry with the unit cell volume six times bigger than the volume of the high‐temperature phase. Although the unit cell volume changes continuously with temperature, all other geometric parameters of the unit cell (a, b, c, β) change in a discrete manner during the phase transition. We propose a model explaining the structural disorder observed at high temperature and discuss the variation of properties of weak interactions on decrease of symmetry. Copyright © 2005 John Wiley & Sons, Ltd.
Role of hydrogen‐bonded nucleophiles in aromatic nucleophilic substitutions in aprotic solvents. reactions of halonitrobenzenes with ethylenediamine, 3‐dimethylamino‐1‐propylamine and histamine in toluene
Authors: Alvaro Cecilia E. Silvana , Nudelman Norma Sbarbati
Published: June 2005

The kinetics of the reactions between 1‐halogeno‐2,4‐dinitrobenzene (halogen = F, Cl) and the amines ethylenediamine (EDA) and 3‐dimethylamino‐1‐propylamine (DMPA) were studied in toluene at 25° ± 0.2C under pseudo‐first‐order conditions using varying amounts of amine. Even with Cl as the nucleofugue (where usually the first step is rate‐determining), a third‐order‐in‐amine kinetic law was observed: these results can be interpreted within the ‘dimer nucleophile’ mechanism where the amine homo‐aggregates are better nucleophiles than the amine monomers. To confirm this interpretation, the reaction of 2,4‐dinitrofluorobenzene with histamine was studied in the same solvent. Because of the rigid geometry, an intramolecular hydrogen bond is easily established, which prevents the formation of self‐aggregates. Consequently, the plot ofkAvs. [histamine] is a straight line, as expected for a classical mechanism of base‐catalysed decomposition of the zwitterionic intermediate. All these results are well explained in the frame of the ‘dimer nucleophile’ mechanism. Copyright © 2005 John Wiley & Sons, Ltd.
Relation between resonance energy and substituent resonance effect in P‐phenols
Authors: Krygowski Tadeusz M. , Stępień Beata T. , Cyrański Michal K. , Ejsmont Krzysztof
Published: June 2005

Molecular geometries of phenol and its 17 p‐substituted derivatives were optimized at the B3LYP/6–311 + G** level of theory. Three homodesmotic and three isodesmotic reaction schemes were used to estimate aromatic stabilization energies (ASE) and the substituent effect stabilization energy (SESE). Other descriptors of π‐electron delocalization (HOMA and NICS, NICS(1) and NICS(1)zz) were also estimated. The SESE and ASE values correlated well with one another as well as with substituent constants. Much worse correlations with substituent constants were found for other aromaticity indices. The NICS(1)zz values are the most negative for unsubstituted phenol, indicating its highest aromaticity; that was not the case for NICS(1) and NICS. Copyright © 2005 John Wiley & Sons, Ltd.
Effects of formulation variables on liquid‐crystal droplet size distributions in ultraviolet‐cured polymer‐dispersed liquid‐crystal cells
Authors: Henry R. M. , Sharma S. C. , Ramsey R. A. , Cramer M. L. , Atman J. B.
Published: June 2005

The size distributions of liquid‐crystal droplets in ultraviolet‐cured polymer‐dispersed liquid‐crystal cells have been studied with optical microscopy. It has been observed that (1) the relative masses of the liquid crystal and crosslinking agent determine the droplet size distribution for submicrometer droplet diameters and (2) only the liquid‐crystal mass fraction affects the droplet size distribution for diameters ranging from 1 to 4 μm. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1842–1848, 2005
Role of molten fraction on the structural evolution in stretching and cooling of crosslinked low‐density polyethylene: Real‐time mechano‐optical measurements
Authors: Koike Yutaka , Cakmak Miko
Published: June 2005

We investigated the uniaxial deformation behavior of crosslinked low‐density polyethylene in partially and substantially molten states using a real‐time true stress–strain birefringence system. The stress–birefringence behavior exhibits a multiregime behavior during stretching and holding process. The details of this regime behavior are primarily governed by the degree of unmelted crystallinity as it has a dominant role in the long‐range structural connectivity. When the long‐range physical connectivity is present, a three‐regime nonlinear stress–optical behavior was observed. When the long‐range connectivity is substantially eliminated at higher temperatures, the regime I behavior disappears. Structural studies including cooling process reveal that the lower the proportion of molten material during stretching, the higher the concentration of fibrillar structure and the shorter are the lengths of the kebabs that exhibit twisted lamellae after solidification. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1825–1841, 2005
Inhibitors of biotin biosynthesis as potential herbicides: Part 2
Authors: Ashkenazi Tali , Widberg Ayala , Nudelman Abraham , Wittenbach Vernon , Flint Dennis
Published: June 2005

Isosteres and analogues of 7‐keto‐8‐aminopelargonic acid (KAPA) and 7,8‐diaminopelargonic acid (DAPA), the vitamer intermediates involved in the biosynthetic pathway of biotin, possessing chain lengths of eight carbon atoms, were prepared and evaluated as potential herbicides. The most active compounds, 7‐amino‐octanoic acid hydrochloride and 7‐allyloxy‐6‐oxo‐octanoic acid, displayed Arabidopsis GR50 (concentration of the active compound that causes a 50% growth inhibition) values of 5 and 10 mg kg−1 respectively. The DAPA analog 6,7‐diamino‐octanoic acid dihydrochloride, when tested in the greenhouse against six weed species, displayed moderate activity against three species, being most active against foxtail millet. Copyright © 2005 Society of Chemical Industry
Quantification of cross‐sectional morphology of porous silicon using stochastic signal spectroscopy
Authors: Parkhutik Vitali , Makusok Yuri , Inumaru Kei , Harima Yutaka
Published: June 2005

Scanning probe microscopy is presently a useful tool to study a morphology of porous semiconductors. However, it serves to visualize existing roughness features of porous samples rather then to obtain some analytical data on shape, diameter and other geometrical parameters of the pores. In this work we show the possibilities of obtaining quantitative information on the porous silicon samples through application of a so‐called Spectroscopy of Stochastic Signals (3S) to their surface profiles obtained using AFM. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphology and chemical composition microanalysis of 2D and 3D ordered structures on porous InP
Authors: Langa S. , Sirbu L. , Monaico E. , Carstensen J. , Föll H. , Tiginyanu I. M.
Published: June 2005

Porous InP proves to be promising for use in nanotechnologies due to the possibility to fabricate ordered structures like two‐dimensional (2D) single crystals of nanopores. The main goal of this paper is to demonstrate that, along with 2D structures, one can fabricate 3D ordered porous structures on InP using alternative anodic current superimposed to a constant current or by pulsing the current. The dependence of the efficiency of pore diameter modulation upon the current frequency was explored. The stoichiometric composition of 2D and 3D porous InP structures was evidenced by chemical composition microanalysis. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of self‐aligned gated silicon microtip array using electrochemical silicon etching
Authors: Barillaro G. , D'Angelo F. , Pennelli G. , Pieri F.
Published: June 2005

In this paper we report a new approach to fabricate gated silicon microtip arrays for field emission applications using a single mask process. The key role in the fabrication process is played by the photoelectrochemical etching of silicon in HF‐based electrolytes. This technique is here exploited to produce highly uniform silicon microtip arrays. The fabrication process is detailed and the dependence of the tip geometry on the electrochemical etching parameters is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porous silicon‐based scaffolds for tissue engineering and other biomedical applications
Authors: Coffer Jeffery L. , Whitehead Melanie A. , Nagesha Dattatri K. , Mukherjee Priyabrata , Akkaraju Giridhar , Totolici Mihaela , Saffie Roghieh S. , Canham Leigh T.
Published: June 2005

This work describes the formation of porous composite materials based on a combination of bioactive mesoporous silicon and bioerodible polymers such as poly‐caprolactone (PCL). The fabrication of a range of composites prepared by both salt leaching and microemulsion techniques are discussed. Particular attention to the influence of Si content in the composite on in vitro calcification assays are assessed. For each system, cytotoxicity and cellular proliferation are explicitly evaluated through fibroblast cell culture assays. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Can chemically etched germanium or germanium nanocrystals emit visible photoluminescence?
Authors: Kartopu G. , Karavanskii V. A. , Serincan U. , Turan R. , Hummel R. E. , Ekinci Y. , Gunnæs A. , Finstad T. G.
Published: June 2005

Photoluminescence (PL) properties of various Ge‐based nanostructured materials, prepared using methods such as chemical etching, ion implantation and spark processing, have been studied. The PL was much stronger from the samples containing Ge nanocrystals, in comparison with their counterparts with no or less Ge nanoparticles, hinting at the likely role of the quantum confinement in Ge nanocrystals (NCs) in the light emission process. On the other hand, defects in the oxides or Ge–O bonded material alone are also shown to emit light in the same energy zone as with the Ge NCs. Discussion on these results is presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties and tunability of macroporous silicon 2‐D photonic bandgap structures
Authors: Haurylau M. , Shroff A. R. , Fauchet P. M.
Published: June 2005

Photonic bandgap (PBG) materials offer an attractive and compact way of integrating the building blocks for optical interconnects and optoelectronic circuits. In this work we demonstrate 2‐D macroporous silicon PBG structures fabricated using interferometric lithography and electrochemical etching of silicon. Optical measurements match well with simulations. We achieve tuning of the PBG using liquid crystals (LCs) infiltrated inside the porous silicon. Surface treatment methods for controlling the initial LC molecule orientation inside the pores are also demonstrated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impedance spectroscopy study of anodic growth of zirconium oxide film in NaOH medium
Authors: Pauporté T. , Finne J. , Lincot D.
Published: June 2005

The growth of anodic oxide films on zirconium metal has been followed up to 300 V by electrochemical impedance spectroscopy and scanning electron microscopy. The maximum layer thickness is 720 nm, the dielectric constant of the film is measured at 19.5 and the growth constant is 2.4 nm V–1. Above 50 V, the presence of two impedance relaxations between 1 Hz and 200 kHz reveals a bilayered structure. This may be a consequence of a lower resistivity of the outer layer induced by some electrolytic solution infiltration into film defects. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cathodoluminescent properties of tin dioxide sol–gel doped with Tb3+ and Eu3+ grown in porous silicon
Authors: Moadhen A. , Elhouichet H. , Jardin C. , Oueslati M. , Roger J. A.
Published: June 2005

Tin dioxide doped with antimony (SnO2:Sb) and sol–gel doped with terbium (Tb3+) were deposited on porous silicon (PS) layers and on monocrystalline Si wafers. Energy dispersive X‐ray (EDX) analysis and Auger electron spectroscopy (AES) show the presence of tin, oxygen and terbium in the PS matrix. Preliminary measurements on cathodoluminescent emission are presented. The mechanism of rare‐earth emission is discussed through a comparative study of the cathodoluminescence (CL) of SnO2:Sb:Tb3+/PS and SnO2:Sb:Tb3+/Si. A strongly enhanced CL efficiency of SnO2:Sb sol–gel doped with Tb3+ and Eu3+ ions deposited in PS is reported. The enhancement is attributed to a process of excitation transfer between rare‐earth ions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of etching with glycerol, and the interferometric measurements on the interface roughness of porous silicon
Authors: Kan P. Y. Y. , Foss S. E. , Finstad T. G.
Published: June 2005

We have carried out interferometric measurements of interface roughness in‐situ during electrochemical etching of p‐type porous silicon (PS) at room temperature. We found that at a certain porosity (∼70%) and with an electrolyte where a low fraction (10%) of the ethanol was replaced with glycerol, there was a significant decrease of the interface roughness. However, a higher content of glycerol (>10%) increased the surface roughness. We have varied the current density in the electrolytic cell and the HF concentration of the electrolyte. We also found that the porosity of the PS varied only slightly when glycerol at various concentrations was used. This investigation shows that an interferometric technique could be a useful tool for measuring the etch rate and the interface roughness of the PS. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Infrared analysis of porous silicon carbide
Authors: Rossi A. M. , Giorgis F. , Ballarini V. , Borini S.
Published: June 2005

We report on the optical spectroscopies performed on porous SiC obtained by electrochemical etching of 6H–SiC wafers. Strong modifications of Raman and infrared spectra, characteristic of the porous material, have been detected. Various effective medium approximations have been employed for the modeling of porous SiC dielectric function, in order to interpret the infrared reflectance features. Comparison between computational and experimental results indicates the Maxwell–Garnett model as the most appropriate approximation, and suggests that charge carriers within the porous matrix are likely to play a role in the interaction of the material with electromagnetic radiation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the mechanism of photodegradation of porous silicon in oxygen‐containing ambient
Authors: Saren A. A. , Kuznetsov S. N. , Pikulev V. B. , Gardin Yu. E. , Gurtov V. A.
Published: June 2005

An explanation of the mechanism of porous silicon (PS) photodegradation in an oxygen‐containing ambient has been proposed. The specific oxidation of luminescent Si nanocrystallites in a porous layer occurs via an intermediate specie, namely ozone produced in oxygen under illumination over a wide range of photon energies. It is shown by photoluminescence (PL), electron spin resonance (ESR) and capacitance–voltage methods that ozone‐induced oxidation is accompanied by defect generation at the Si crystallite/oxide interface. Some of these centers act as a nonradiative drain for electron–hole pairs under PL excitation. As revealed by capacitance spectroscopy in an MOS structure with a porous sublayer, these defects constitute an interface states spectrum broadly spread through the silicon band gap. The above‐mentioned defects appear in ESR spectra as Pb‐like centers originated from incomplete passivation of silicon bonds with oxygen at the crystallite surface. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FTIR investigation of porous silicon formed in deutrofluoric acid based solutions
Authors: Belogorokhov A. I. , Gavrilov S. A. , Kashkarov P. K. , Belogorokhov I. A.
Published: June 2005

Absorption of infrared radiation in the porous silicon (PS) films prepared by common electrochemical etching in DF‐ethanol‐D6 solutions was studied. We report our results of the effect of deuterium termination on the process of surface states changes of the PS after their exposure to ambient air for few months. In addition to these results, we also show that the replacement of hydrogen with deuterium leads to decreasing the concentration of the silicon dangling bonds at the surface of the PS. As a result, more stable passivation layer was formed. There were not any detectable quantities of the hydrogen atoms at the surface of PS during few months after its preparation. This fact is explained from the point of view of the dissociative water adsorption mechanism. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of oscillatory behavior of open‐circuit potential of silicon immersed in CuSO4/HF solutions
Authors: Parkhutik V. , Rayon E. , Pastor E. , Matveeva E. , Sasano J. , Ogata Y.
Published: June 2005

This work studies the influence of experimental conditions on the occurrence and development of oscillations of the open‐circuit potential (OCP) of silicon immersed in aqueous solution of 0.01 M CuSO4 + 0.06 M HF. The oscillations are very regular and last for days without any tendency to diminish. We show that they are quite sensitive to the temperature of the electrolyte, its viscosity, stirring, relative concentration of components, etc. We also present a phenomenological model to explain the oscillatory OCP behavior. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of drug load in porous silicon microparticles by calorimetry
Authors: Salonen J. , Paski J. , Vähä‐Heikkilä K. , Heikkilä T. , Björkqvist M. , Lehto V.‐P.
Published: June 2005

Different kind of drugs can be loaded into the porous silicon microparticles for oral dosing. In cases where the drug is in its crystalline form in the pores, the amount of the loaded drug can be determined accurately using a calorimetric method, thermoporometry. Even if the drug substance is not in crystalline form a sophisticated estimation can be given. In this work ibuprofen, antipyrine, and ranitidine have been studied. Ibuprofen and antipyrine were easily detected and quantified, but ranitidine, which does not penetrate into the PSi microparticles in its crystalline form, could only be qualitatively determined. The possibility to quantify this kind of drug substance is also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)