bluuebunny/crossref_metadata_2025_split huggingface dataset:
From temporary help jobs to permanent employment: what can we learn from matching estimators and their sensitivity?
Authors: Ichino Andrea , Mealli Fabrizia , Nannicini Tommaso 
Published: April 2008

AbstractThe diffusion of temporary work agency (TWA) jobs has led to a harsh policy debate and ambiguous empirical evidence. Results for the USA, based on quasi‐experimental evidence, suggest that a TWA assignment decreases the probability of finding a stable job, while results for Europe, based on the conditional independence assumption (CIA), typically reach opposite conclusions. Using data for two Italian regions, we rely on a matching estimator to show that TWA assignments can be an effective springboard to permanent employment. We also propose a simulation‐based sensitivity analysis, which highlights that only for one of these two regions are our results robust to specific failures of the CIA. We conclude that European studies based on the CIA should not be automatically discarded, but should be put under the scrutiny of a sensitivity analysis like the one we propose. Copyright © 2008 John Wiley & Sons, Ltd.
Two decadally resolved records from north‐west European peat bogs show rapid climate changes associated with solar variability during the mid–late Holocene
Authors: Mauquoy Dmitri , Yeloff Dan , Van Geel Bas , Charman Dan J. , Blundell Antony 
Published: April 2008

AbstractTwo 14C accelerator mass spectrometry (AMS) wiggle‐match dated peat sequences from Denmark and northern England record changes in mire surface wetness reconstructed using plant macrofossil and testate amoebae analyses. A number of significant mid–late Holocene climatic deteriorations (wet shifts) associated with declines in solar activity were recorded (at ca. 2150 cal. yr BC, 740 cal. yr BC, cal. yr AD 930, cal. yr AD 1020, cal. yr AD 1280–1300, cal. yr AD 1640 and cal. yr AD 1790–1830). The wet shifts identified from ca. cal. yr AD 930 are concurrent with or lag decreases in solar activity by 10–50 years. These changes are replicated by previous records from these and other sites in the region and the new records provide improved precision for the ages of these changes. The rapidly accumulating (up to 2–3 yr cm−1, ∼1310 yr old, 34 14C dates) Danish profile offers an unprecedented high‐resolution record of climate change from a peat bog, and has effectively recorded a number of significant but short‐lived climate change events since ca. cal. yr AD 690. The longer time intervals between samples and the greater length of time resolved by each sample in the British site due to slower peat accumulation rates (up to 11 yr cm−1, ∼5250 yr old, 42 14C dates) acted as a natural smoothing filter preventing the clear registration of some of the rapid climate change events. Not all the significant rises in water table registered in the peat bog archives of the British and Danish sites have been caused by solar forcing, and may be the result of other processes such as changes in other external forcing factors, the internal variability of the climate system or raised bog ecosystem. Copyright © 2008 John Wiley & Sons, Ltd.
Predictability of price of tea from sensory assessments and biochemical information using data‐mining techniques
Authors: Paul Sanjoy K 
Published: April 2008

AbstractBACKGROUND: The valuation of tea depends on the sensory assessments made by the Brokers and Buyers (Tea Tasters) to a large extent, though the market conditions and the requirements of a particular Buyer play an important role in determining the basic prices of teas. Again, there are several biochemical quality parameters in tea on which the quality of a particular tea depends. It is not straightforward to establish the reflection of biochemical quality characteristics in tea on the Taster's sensory assessments and price because of the complex dynamics within chemical properties and the inherent subjectivity of quality evaluation through the Taster's scores. It is, however, important to judge the market valuation of teas from quality assessments and biochemical properties. This paper describes the advantages of using statistical data‐mining techniques to explore the association of biochemical quality parameters in teas with the Taster's sensory assessments, and the application of a nonparametric statistical technique, multivariate adaptive regression splines (MARSplines), to establish the predictability of the realised prices of teas from sensory assessments.RESULTS: The price of tea is significantly associated with various quality attributes and some of the biochemical parameters. The MARSplines technique successfully demonstrated the predictability of price through Tasters' sensory assessments and also raised the issue of inherent subjectivity of the Tasters' assessments.CONCLUSION: It is important to explore appropriate statistical techniques to assess the subjectivity in Tasters' assessments, and a better‐designed study needs to be conducted to understand the complex biochemical reflections on the price of tea. Copyright © 2008 Society of Chemical Industry
Chiral separations in sub‐ and supercritical fluid chromatography
Authors: Mangelings Debby , Vander Heyden Yvan 
Published: April 2008

AbstractSub‐ and supercritical fluid chromatography (SFC) received more and more attention in pharmaceutical analysis during the last years. Especially for chiral separations, this technique is becoming increasingly popular. This review gives an overview of most chiral separation applications using SFC, covering the literature from 2000 on.
The advantages of ESI‐MS detection in conjunction with HILIC mode separations: Fundamentals and applications
Authors: Nguyen Hien P. , Schug Kevin A. 
Published: April 2008

AbstractThe analysis of highly hydrophilic, ionic, and polar compounds has been performed by HILIC‐ESI‐MS for the last few years. The use of low aqueous/high polar organic solvent content in HILIC separation mobile phase is almost ideal for ESI‐MS detection in many cases, resulting in increased sensitivity. Although the addition of modifiers such as acids or salts is necessary in some circumstances for a good separation, the optimum concentrations used are still highly amenable for ESI‐MS analysis, showing few deleterious effects. In this review, the mechanism of HILIC separation and ESI ion generation will be briefly discussed, followed by a summary of method development and applications in several fields of research including pharmaceutical, biomolecular, food, metabolic, and environmental analysis.
Grafting BSA onto Poly[(L‐lactide)‐co‐carbonate] Microspheres by Click Chemistry
Authors: Han Yadong , Shi Quan , Hu Junli , Du Qing , Chen Xuesi , Jing Xiabin 
Published: April 2008

AbstractModel protein bovine serum albumin (BSA) was covalently grafted onto poly[(L‐lactide)‐co‐carbonate] microsphere surfaces by “click chemistry.” The grafting was confirmed by confocal laser scanning microscopy and X‐ray photoelectron spectroscopy. The maximum amount of surface‐grafted BSA was 45 mg · g−1. The secondary structure of the grafted BSA was analyzed by FTIR and the results demonstrated that the grafting did not affect protein structure. This strategy can also be used on microspheres prepared from poly(L‐lactide)/poly[(L‐lactide)‐co‐carbonate] blend materials.magnified image
Release of Prostaglandin E1 from N‐(2‐Hydroxypropyl)methacrylamide Copolymer Conjugates by Bone Cells
Authors: Pan Huaizhong , Liu Jihua , Dong Yuanyi , Sima Monika , Kopečková Pavla , Brandi Maria Luisa , Kopeček Jindřich 
Published: April 2008

AbstractBone‐targeting N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer‐PGE1 conjugates, containing cathepsin K sensitive spacers, were incubated with induced osteoclasts and osteoblasts, their precursors, and control non‐skeletal cells. The release of PGE1 was monitored by an HPLC assay. In both murine and human cell lines, osteoclasts appeared to be the most active cells in the cleavage (PGE1 release). Incubation with osteoblasts also resulted in fast PGE1 release, whereas precursor and control cells released PGE1 with a substantially slower rate than bone cells (apparently through ester bond cleavage). Experiments in the presence of inhibitors revealed that other enzymes, in addition to cathepsin K, were participating in the cleavage of the conjugate. Confocal fluorescence studies exposed internalization of the conjugate by endocytosis with ultimate localization in the lysosomal/endosomal compartment.magnified image
Effect of pre‐oxidation on coke formation and metal dusting of electroplated Ni3Al–CeO2‐based coatings in CO–H2–H2O
Authors: Liu H. , Chen W. 
Published: April 2008

AbstractPre‐oxidation was introduced to improve the resistance of electroplated pure, 5 µm CeO2‐dispersed, and 9–15 nm CeO2‐dispersed Ni3Al coatings to coke formation and metal dusting in 24.4%CO–73.3%H2–2.3%H2O at 650 °C. Coke formation and metal dusting of pre‐oxidized Ni3Al‐based coatings were retarded up to 200 h owing to a thin Al2O3 scale induced during pre‐oxidation. The long‐term effectiveness of pre‐oxidation nonetheless depended on the integrity of Al2O3 scale. The pure Ni3Al coating suffered severe spallation after pre‐oxidation and thereby showed the worst long‐term resistance. Two pre‐treated 9–15 nm CeO2‐dispersed Ni3Al coatings exhibited the best long‐term resistance to carbon attack because nano‐CeO2 particles maintained a full coverage of Al2O3 scale on the coatings. Two 5 µm CeO2‐dispersed Ni3Al coatings showed significant spallation after pre‐oxidation because of an overdoping effect and experienced coke formation and metal dusting during long‐term exposure.
Corrosion protection properties of copper‐ and carbon‐containing polyethylene films in humid air climates
Authors: Köhler S. , Rammelt U. , Reinhard G. 
Published: April 2008

AbstractThe corrosion protection properties of commercially available polyethylene (PE) films containing copper and carbon were investigated and compared with pure PE films of comparable thickness. The composition of these films was analyzed by thermoanalysis and atom emission spectroscopy (ICP‐AES). Electrochemical impedance spectroscopy (EIS) and packaging tests were used to determine the ability of copper‐ and carbon‐containing PE films to protect mild steel against corrosion in humid air climates. For the here‐investigated samples, no electrochemical activity of copper could be found under these conditions. In contrast to the added copper only the inserted carbon decreased the surface resistance. Additional abrasive tests imply that copper is encapsulated inside the films. For all samples, the permeability to vapor and the insertion of water were similar to the copper and carbon free reference film. The tests in the climate cabinet revealed that mild steel samples packed in copper‐ and carbon‐containing films reached the same degree of corrosion than those in the reference films.
Hydrogen degradation of structural steels in technical hydrocarbon liquids
Authors: Swieczko‐Zurek B. , Zielinski A. , Lunarska E. 
Published: April 2008

AbstractHydrogen absorption, mechanical testing under different loading mode and electrochemical measurement were done for 0.3C low alloy steels used in the ship engine parts at immersion in the boiler fuel and in the used engine mineral oil at elevated temperatures corresponding to the operating conditions. The hydrogen charging of steels has been found to reach a level causing their plasticity loss. No effect, a plasticity loss and a significant decrease in the number of cycles have been stated in constant load, slow strain rate and fatigue tests, respectively. The results showed the local active plastic deformation proceeded close to the surface of hydrogen ingress to provide the highest possibility for hydrogen induced metal degradation in hydrocarbon environments. Although the source of hydrogen evolved in the case of technical hydrocarbons has been discussed, the promoting effect of formed H2S should be recognized as the important factor influencing the hydrogen charging from those environments. Some variation in the steel microstructure, chemical composition and hardness of steels, even allowed by the standard may affect their susceptibility to hydrogen degradation in hydrocarbons.
Galvanic compatibility of corrosion protective coatings with AA7075 aluminum alloy
Authors: Lodhi Z. F. , Hamer W. J. , Mol J. M. C. , Terryn H. , de Wit J. H. W. 
Published: April 2008

AbstractThe galvanic compatibility of aerospace aluminum alloy AA7075 with cadmium (Cd), zinc (Zn), and zinc–cobalt–iron (Zn–Co–Fe, 32–37%Co and 1%Fe) alloys was investigated. A comparison of open circuit potential [OCP vs. saturated calomel electrode (SCE)] measurements in 0.6 mM NaCl showed that all coatings would act anodically to AA7075 with an exception of Zn–Co–Fe (37%Co + 1%Fe) alloy which was electropositive to AA7075. During the zero resistance ammetry (ZRA) measurement in 0.6 M NaCl electrolyte the coupled OCP and current density were measured during 7 days of immersion and both Zn and Cd acted anodic and thus sacrificial to AA7075. Galvanic coupling of AA7075 with (37%Co + 1%Fe) Zn–Co–Fe alloy resulted in the consequent dissolution of the AA7075 aluminum alloy. In contrast, Zn–Co–Fe (32%Co + 1%Fe) alloy was found to be anodic to AA7075 during the first 26 h of immersion but after dezincification and cobalt enrichment at the surface became cathodic to the AA7075 aluminum alloy. During coupling with Zn, some pitting was also observed on AA7075.
Electrodeposited nickel/alumina composite coating on NdFeB permanent magnets
Authors: Zhang H. , Song Y. W. , Song Z. L. 
Published: April 2008

AbstractNdFeB magnets are highly susceptible to corrosion in various environments. A nickel/alumina composite coating for NdFeB magnets was investigated in this paper. The microstructures of electrodeposited nickel coating and nickel/alumina composite coating were determined by scanning electron microscope (SEM). The corrosion behavior of nickel coating and nickel/alumina composite coating in 3.5 wt% sodium chloride solution was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the nickel coating and nickel/alumina composite coating can both provide adequate protection to the NdFeB substrate. Furthermore, the free corrosion potential of nickel/alumina composite coating is more positive and the passivation region is more obvious compared with nickel coating, and the capacitance loop diameter of nickel/alumina composite coating is significantly larger than that of nickel coating. With the increase in immersion time, a flat of passivation film is formed on the surface of nickel/alumina composite coating, resulting in excellent corrosion resistance after 288 h immersion in 3.5% sodium chloride solution according to EIS testing.
Recent Advances in Reactive Extrusion Processing of Biodegradable Polymer‐Based Compositions
Authors: Raquez Jean‐Marie , Narayan Ramani , Dubois Philippe 
Published: April 2008

AbstractThis review reports on recent advances in the design of biodegradable polymers built from petroleum and renewable resources using reactive extrusion processing. Reactive extrusion represents a unique tool to manufacture biodegradable polymers upon different types of reactive modification in a cost‐effective way. Partially based on our ongoing research, ring‐opening polymerization of biodegradable polyesters will be approached as well as the chemical modification of biodegradable polymers, particularly natural polymers. The development of environmentally friendly polymer blends as well as (nano)composites from natural polymers, including natural fibers and nanoclays, through reactive extrusion, as an efficient way to improve the interfacial adhesion between these components, will be also discussed.magnified image
Ferroelectric Polymer Nanotubes with Large Dielectric Constants for Potential All‐Organic Electronic Devices
Authors: Wang Chang‐Chun , Shen Qun‐Dong , Tang Shao‐Chun , Wu Qiang , Bao Hui‐Min , Yang Chang‐Zheng , Jiang Xi‐Qun 
Published: April 2008

AbstractTo fabricate ferroelectric ultrathin polymer films with large dielectric constants for potential all‐organic electronic devices, ferroelectric polymer nanotubes and a composite of the nanotubes with a dispersed organic semiconductor have been fabricated by template‐assisted methods. The ferroelectricity drops markedly in spin‐coated ultrathin films less than 100 nm thick, whereas P(VDF‐TrFE) nanotubes with a wall thickness of a few ten nm sustain ferroelectricity. The composite nanotubes exhibit a giant dielectric constant as a result of significantly enhanced interface polarization between the nanosized fillers and the polymer matrix. They could be of practical use in supercapacitors, optoelectronic devices, and sensors.magnified image
Responsive Polymer‐Protein Bioconjugates Prepared by RAFT Polymerization and Copper‐Catalyzed Azide‐Alkyne Click Chemistry
Authors: Li Ming , De Priyadarsi , Gondi Sudershan R. , Sumerlin Brent S. 
Published: April 2008

AbstractResponsive polymer‐protein conjugates were synthesized by combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and a grafting‐to approach by a highly efficient “click chemistry” strategy. A model protein, bovine serum albumin (BSA), was functionalized with an alkyne moiety by reaction of its free cysteine residue with propargyl maleimide. Azido‐terminated poly(N‐isopropylacrylamide) (PNIPAM‐N3) was prepared via RAFT, and polymer‐protein coupling was accomplished by copper‐catalyzed azide‐alkyne cycloaddition. In aqueous solution, the conjugates were observed by dynamic light scattering to be larger than the free polymer or the unmodified protein. Upon heating above the PNIPAM lower critical solution temperature (LCST), the PNIPAM‐BSA bioconjugates formed stable nanoparticles composed of dehydrated polymer and hydrophilic protein.magnified image
1H chemical shifts in NMR. Part 27: proton chemical shifts in sulfoxides and sulfones and the magnetic anisotropy, electric field and steric effects of the SO bond
Authors: Abraham Raymond J. , Byrne Jonathan J. , Griffiths Lee 
Published: April 2008

AbstractThe 1H chemical shifts of a series of sulfoxide and sulfone compounds in CDCl3 solvent were obtained from experiment and the literature. These included dialkyl sulfoxides and sulfones (R2SO/R2SO2, R = Me, Et, Pr, n‐Bu), the cyclic compounds tetramethylene sulfoxide/sulfone, pentamethylene sulfoxide/sulfone and the aromatic compounds p‐tolylmethylsulfoxide, dibenzothiopheneoxide/dioxide, E‐9‐phenanthrylmethylsulfoxide and (E) (Z)‐1‐methylsulfinyl‐2‐methylnaphthalene. The spectra of the pentamethylene SO and SO2 compounds were obtained at −70 °C to obtain the spectra from the separate conformers (SO) and from the noninverting ring (SO2). This allowed the determination of the substituent chemical shifts (SCS) of the SO and SO2 functional groups, which were analyzed in terms of the SO bond electric field, magnetic anisotropy and steric effect for long‐range protons together with a model (CHARGE8d) for the calculation of the two and three bond effects. After parameterization, the overall root mean square (RMS) error (observed‐calculated) for a dataset of 354 1H chemical shifts was 0.11 ppm. The anisotropy of the SO bond was found to be very small, supporting the dominant single bond S+O− character of this bond. Copyright © 2008 John Wiley & Sons, Ltd.
Determination of β‐carboline alkaloids in fruiting bodies of Hygrophorus spp. by liquid chromatography/electrospray ionisation tandem mass spectrometry
Authors: Teichert Axel , Lübken Tilo , Schmidt Jürgen , Kuhnt Christine , Huth Manfred , Porzel Andrea , Wessjohann Ludger , Arnold Norbert 
Published: April 2008

AbstractThe β‐carboline alkaloids harmane (1) and norharmane (2) were isolated from fruiting bodies of Hygrophorus eburneus (Bull.) Fr. as well as brunnein A (3) from Hygrophorus hyacinthinus Quél. (Tricholomataceae, Agaricales) for the first time. Their occurrence within the genus was investigated using liquid chromatography/electrospray ionisation tandem mass spectrometric methods, especially by selected reaction monitoring. Based on these results their chemotaxonomical relevance is discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Real‐time fluorescence‐based detection of furanocoumarin photoadducts of DNA
Authors: Bissonnette Laura , Arnason John T. , Smith Myron L. 
Published: April 2008

AbstractReal‐time fluorescence detection systems were adapted to identify DNA adducts formed by photogenotoxic phytochemicals. Two assays were developed: the first was based on quantitative polymerase chain reaction (qPCR) while the second used thermal denaturation and renaturation (D‐R). Both assays employed yeast DNA, the fluorescent dye SYBR Green and a real‐time PCR thermocycler. The furanocoumarins 8‐methoxypsoralen (8‐MOP), 5‐methoxypsoralen (5‐MOP), psoralen, angelicin and imperatorin, and the furanochrome khellin, were tested for adduct forming ability with up to 2 h of UVA light exposure (λ = 320–400 nm). The known bifunctional compounds, 8‐MOP, 5‐MOP and psoralen, were inferred to form biadducts here based on both D‐R and qPCR assays, as expected from previous research. The known monofunctional compound angelicin was used as a negative control and did not form biadducts based on either assay. Two compounds of unknown functional specificity, imperatorin and khellin, were determined to be positive and negative for biadduct activity, respectively. Detection of biadducts with 8‐MOP, 5‐MOP, psoralen and imperatorin, but not angelicin or khellin, was further verified by temperature gradient gel electrophoresis. The fluorescence methods improve and expand upon existing assays to monitor DNA adducts. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis, characterization, and thermal properties of ring‐opening metathesis polynorbornenes and their hydrogenated derivatives bearing various ester and cyano groups
Authors: Nishihara Yasushi , Izawa Seisuke , Inoue Yoshiaki , Nakayama Yuushou , Shiono Takeshi , Takagi Kentaro 
Published: April 2008

AbstractDoubly functionalized polar norbornenes 3a–3g substituted by both a variety of ester and cyano groups were polymerized by ring‐opening metathesis polymerization (ROMP) with a Ru carbene complex 2 bearing 3‐bromopyridine as a ligand (third generation Grubbs' catalyst) in a living manner. The successive hydrogenation of the main‐chain double bond in the synthesized living ROMP polymers 4a–4g with a hydridoruthenium complex was exploited. The comparison of thermal properties of a series of ring‐opening metathesis polymers 4a–4g with those of their hydrogenated derivatives 5a–5g revealed the decrease of glass transition temperatures (Tg) but little change of the 5% decomposition temperature (Td5). In all cases examined in this study, a decrease of Tg by hydrogenation was around 20–40 °C, regardless of the ester substitutents. In the presence of the additional PCy3, triethylamine, and methanol after complete consumption of monomer 3a under the living ROMP condition, the tandem ROMP‐hydrogenation of the resulting polymer 4a generated in situ was attained under a H2 (9.8 MPa) atmosphere at 80 °C to afford the hydrogenated polymer 5a, retaining the narrow polydispersity of 1.03. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3314–3325 2008
Surface Radical Detection on NH3‐Plasma Treated Polymer Surfaces Using the Radical Scavenger NO
Authors: Finke Birgit , Schröder Karsten , Ohl Andreas 
Published: April 2008

AbstractPolystyrene was treated by low‐pressure microwave‐excited ammonia plasmas to generate surface amino groups and subsequently treated with NO to label the remaining carbon radicals for in situ detection by XPS. Short time treatments between 5 ms and 40 s duration were used to vary densities of amino groups and radicals and thus to distinguish different reaction pathways. Apparently, after less than 30 ms treatment no tertiary carbon radicals exist. Also, there are indications that amino groups react with NO to carbon radicals which in turn react with NO. A more detailed study of surface radical generation at very low treatment times would be promising.magnified image