bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic solvent extraction and nonaqueous CE for the determination of herbicide residues in potatoes
Authors: Rodríguez‐Gonzalo Encarnación , Carabias‐Martínez Rita , Cruz Edith Miranda , Domínguez‐Álvarez Javier , Hernández‐Méndez Jesús 
Published: February 2009

AbstractIn the present work we address the development of a simple and effective method for the determination of triazine herbicide residues in horticultural products by CE in nonaqueous media (NACE). Potato samples were selected as a representative matrix of such foods with a nonfatty content. Isolation of the analytes from the sample matrix was accomplished by extraction with organic solvents, assisted by ultrasound; a clean‐up step of the organic extracts was carried out with SPE, using an Oasis MCX® sorbent to retain the analytes directly from the organic medium. The detection limits achieved in spiked potatoes (1.7–4.0 μg/kg) were lower than the default value of maximum residue level (MRL) established by current EU legislation for pesticide residues in foodstuffs. The results obtained were compared with HPLC in order to evaluate the performance of the NACE procedure.
Analytical bias among different gas chromatographic approaches using standard BTX gases and exhaust samples
Authors: Kim Ki‐Hyun , Pandey Sudhir Kumar , Pal Raktim 
Published: February 2009

AbstractIn this study, the analytical compatibility of the gas chromatographic (GC) approach was evaluated through a cross‐calibration exercise. To this end, three aromatic volatile organic compounds (VOCs: benzene, toluene, and p‐xylene (BTX)) were simultaneously analyzed with four individual instrumental setups (type I = GC with MS plus solid phase microextraction (SPME) method, II = GC with flame ionization detection (FID) plus SPME, III = fast GC‐FID plus SPME, and IV = GC‐FID plus air server/thermal desorption (AS/TD) method). A comparison of basic quality assurance (QA) data revealed considerable differences in DL values among the methods with moderate variabilities in the intercompound sensitivity. In light of the differences in detection properties, the analytical bias involved for each methodological approach was assessed by the relative relationship between analytes and basic operating conditions. The results suggest that the analysis of environmental samples at ultra‐low concentration levels (at or below ppb level) can be subject to diverse sources of bias. Although detection properties of target compounds seem to be affected by the combined effects of various factors, changes in the sample concentration levels were seen to be the most consistent under the experimental setups analyzed in this study.
Development and validation of a multiresidue method for determination of 82 pesticides in water using GC
Authors: Mamun Md. Iqbal Rouf , Park Jong Hyouk , Choi Jeong‐Heui , Kim Hee Kwon , Choi Woo Jung , Han Seong‐Soo , Hwang Kyungsup , Jang Nam‐IK , Assayed Mohamed Ezzat , El‐Dib Mohamed Anwer , Shin Ho‐Chul , El‐Aty A. M. Abd , Shim Jae‐Han 
Published: February 2009

AbstractSeveral methods used for the multiresidue analysis of pesticides from the environment and drinking water have been reported. However, most of these reports dealt with a small number of targeted pesticides or some special groups. A method that is simple, faster, and more cost‐effective than the environmental protection agency (EPA) method has been developed for the analysis of 82 frequently used pesticides in water samples obtained from Yeongsan and Sumjin rivers, as well as rice fields located in various locations around the two rivers. The samples were extracted by dichloromethane, and the pesticides were analyzed using a GC‐electron capture detector (ECD), followed by confirmation with GC‐MS. Recoveries were found to be between 82 and 120.1% for most of the tested pesticides, which were in agreement with the standard values dictated by the EPA. The method was potentially applied to 66 water samples for human consumption and 90 water samples from the rice fields and irrigation ditches that were collected from June to September 2007. Oxadiazon, butachlor, and alachlor were detected in some of the river water samples collected in June, iprobenfos (IBP) was detected in samples collected in August, and no pesticide was detected in September. On the other hand, chlorpyrifos‐methyl, IBP, hexaconazole, diazinon, oxadiazon, butachlor, and isoprothiolane were detected at relatively high concentrations in 48 rice paddy field water samples collected between June and September 2007. Alachlor in one sample and procymidone in some of the rice paddy field water samples were also detected in trace amounts. The results were consistent with the temporal pattern of pesticide application in Korean rice fields.
Synthesis of Reactive Triblock Copolymers via Reversible Addition‐Fragmentation Chain Transfer (RAFT) Polymerization
Authors: Strube Oliver Ingolf , Schmidt‐Naake Gudrun 
Published: February 2009

AbstractABA and BAB triblock copolymers of vinylbenzyl chloride and styrene with low polydispersity and different block lengths and block length ratios were produced via reversible addition fragmentation chain transfer (RAFT) polymerization. The used RAFT agent butan‐1,4‐diyl‐bis(1‐phenylethyl)trithiocarbonate is a Z‐connected bis‐RAFT‐agent, that allows the synthesis of triblock copolymers in only two steps. The polyvinylbenzyl chloride blocks were quantitatively converted into polyamine blocks by reaction with diethyl amine. All the synthesized block copolymers are microphase separated polymers.
Synthesis and Characterization of Well‐Defined Block Copolymers by Combing Controlled Radical and Cationic Polymerization
Authors: Ibrahim Saber , Voit Brigitte 
Published: February 2009

AbstractA facile synthetic strategy for well‐defined poly(ethyleneimine)‐polystyrene (PEI‐PS) block copolymers utilizing controlled radical polymerization through the macroinitiator approach is presented. Poly(2‐methyl‐2‐oxazoline) containing an alkoxyamine initiating unit at the chain end was prepared by ring opening cationic polymerization of 2‐methyl‐2‐oxazoline through a nitroxide containing initiator. Polymerization of styrene with the poly(2‐methyl‐2‐oxazoline) macroinitiator was carried out under nitroxide‐mediated radical polymerization (NMRP) conditions. GPC and NMR revealed that the polymerization was accurately controlled and well‐defined polystyrene chains were attached to the chain end of the macroinitiator to give the poly(2‐methyl‐2‐oxazoline‐b‐styrene) block copolymers. Hydrolysis of the poly(2‐methyl‐2‐oxazoline) block resulted effectively in poly(ethyleneimine‐b‐styrene) block copolymers.
Tailor Made Side‐Chain Functionalized Macromolecules by Combination of Controlled Radical Polymerization and Click Chemistry
Authors: Krieg Andreas , Becer C. Remzi , Hoogenboom Richard , Schubert Ulrich S. 
Published: February 2009

AbstractReversible addition‐fragmentation chain transfer polymerization of trimethylsilyl‐propargyl methacrylate (TMSPMA) was performed to obtain alkyne containing polymers with narrow molecular weight distributions (PDI < 1.3). Homopolymers of TMSPMA as well as random and block copolymers with methyl methacrylate were synthesized and subsequently deprotected. The obtained acetylene‐functionalized polymers were further functionalized using the copper(I) catalyzed alkyne‐azide cycloaddition reaction to obtain well‐defined glycopolymers, grafted copolymers and anthracene‐containing polymers (PDI = 1.08–1.28) that were characterized with GPC, MALDI‐TOF mass spectrometry and 1H‐NMR‐spectroscopy.
One‐Pot Procedure for the Preparation of Rod‐Coil Block Copolymers via a Bifunctional Initiator
Authors: Niehoff Ansgar , Jurjević Simone , Heise Andreas , Menzel Henning 
Published: February 2009

AbstractThe synthesis of well‐defined polypeptide‐polyvinyl rod coil block copolymers via the combination of Nickel‐mediated ring opening polymerization and atom transfer radical polymerization (ATRP) is described. The strategy for the synthesis is based on a bifunctional initiator. In the first step the poly‐benzyl‐L‐glutamate (PBLG) block is prepared which is subsequently used as a macroinitiator for the ATRP of methyl methacrylate (MMA). These two reaction steps are performed either consecutively by isolation of the PBLG‐macroinitiator or in a one‐pot procedure without isolation of the PBLG‐macroinitiator. By the one‐pot approach the tedious isolation and purification of the macroinitiator is avoided. Reasonable PMMA‐block lengths and low polydispersities indicate a successful synthesis of PBLG‐PMMA block copolymers also via the one‐pot procedure.
Modeling of Emulsion Polymerization, Will It Ever be Possible ? Part‐2: Determination of Basic Kinetic Data Over the Last Ten Years
Authors: van Herk Alexander M. 
Published: February 2009

AbstractModeling of Emulsion polymerization processes is based on the knowledge of fundamental kinetic and thermodynamic parameters. The most important kinetic parameters are propagation and termination rate coefficients. Ten years ago a paper has been published with the title “Modeling of Emulsion Polymerization, will it ever be possible?”. The paper expresses serious doubts whether the different kinetic parameters will ever be available for general industrial recipes containing several monomers. In this paper the developments in the last 10 years regarding pulsed initiation polymerization (PIP) and other techniques regarding the determination of especially the kinetic parameters will be discussed. Amongst the areas where progress can be seen is the understanding of acrylate systems and water soluble monomers. New techniques like MALDI‐ToF MS and time resolved electron spin resonance have strongly contributed to the area. Also the puzzling effect of chain length dependent propagation is discussed. Finally an answer will be given to the title question.
Different Nitroxide‐Capped Polystyrenes and their Behavior During an Analysis via MALDI‐TOF Mass Spectrometry
Authors: Dempwolf Wibke , Flakus Silke , Schmidt‐Naake Gudrun 
Published: February 2009

AbstractDifferent nitroxide‐terminated polystyrenes are characterized using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). Careful MS analysis reveals that in contrast to TEMPO‐capped chains which can be analyzed without fragmentation, a fragmentation of the N‐oxyle group occurs in case of TIPNO and BIPNO. A fragmentation resulting in the loss of a t‐butyl‐group is proposed as consequence of the treatment during the measurement.
MALDI‐TOF MS Investigations of Polyamides Synthesized in Autoclave and Microwave Assisted Processes
Authors: Nothdurft Lars , Bode Ralf , Schmidt‐Naake Gudrun 
Published: February 2009

AbstractDue to their excellent physical and chemical properties polyamides (PA) are used in many industrial processes. The most common products are the aliphatic polyamides synthesized by a conventional melt‐polycondensation method of AH‐salt in an autoclave. High temperatures, high pressure and long reaction times are necessary. On the other hand the polyamide synthesis can conducted as solution polycondensation in a microwave oven. Moreover the higher heating efficiency of microwave irradiation reduces the reaction time to about 20 minutes. The main focus of this study lies on the end group analysis by MALDI‐TOF MS (matrix assisted laser desorption/ionization time of flight mass spectrometry) of aliphatic polyamides produced by autoclave – as well as microwave assisted synthesis by AABB‐type condensation. The results show differences in the end group formation depending on the chosen reaction conditions. In case of following modification or protecting group chemistry, it is of course important to know the kind of end groups of the polyamide.
Online Monitoring of 4‐Vinylbenzene sulfonic acid Sodium Salt – Acrylamide Copolymerization in Water
Authors: Paril Ahmet , Alb Alina M. , Giz Ahmet , Catalgil‐Giz Huceste 
Published: February 2009

Abstract4‐Vinylbenzene sulfonic acid sodium salt (VB) – Acrylamide (Aam) homopolymerization and copolymerization reactions with various feed ratios were performed in water at 60 °C. All reactions were monitored online, by an Automatic Continuous Online Monitoring of Polymerization (ACOMP) system. The concentrations of the two comonomers in their monomeric form, as well as their concentrations incorporated into polymer, were obtained from the monitored data. It was seen that Aam homopolymerization was faster than VB and both homopolymerization rates were higher than copolymerization rates at any combination. In the reactions with 1.5%, 5% and 10% (mol) VB, VB was completely depleted and further reaction was Aam homopolymerization. In the copolymerizations with 5 to 50% initial VB content, the plots of VB fraction in the remaining monomer mixture versus conversion exhibited a corner at 10–30% conversion. This corner showed that the behavior of the reaction changed abruptly at this point. In the first stage of the reactions, the composition was seen to be almost constant with almost no composition drift whereas in the second part, the VB fraction decreased monotonically. Monomer reactivity ratios (MRR) were calculated by error in variables (EVM) method. Since the reactions gave two distinguishable regions, the reaction part before and after the corner were evaluated separately. Therefore, the monomer reactivity ratios were found as rAam = 0.34 ± 0.07, rVB = 0.40 ± 0.21 for the part before and rAam = 0.2 ± 0.04, rVB = 9.0 ± 0.8 for the part after the corner.
Folksonomy and information retrieval
Authors: Peters Isabella , Stock Wolfgang G. 
Published: February 2009

AbstractIn Web 2.0 services “prosumers” ‐ producers and consumers ‐ collaborate not only for the purpose of creating content, but to index these pieces of information as well. Folksonomies permit actors to describe documents with subject headings, “tags“, without regarding any rules. Apart from a lot of benefits folksonomies have many shortcomings (e.g., lack of precision). In order to solve some of the problems we propose interpreting tags as natural language terms. Accordingly, we can introduce methods of NLP to solve the tags' linguistic problems. Additionally we present criteria for tagged documents to create a ranking by relevance (tag distribution, collaboration and actor‐based aspects). We would like to open the discussion concerning the following aspects: Which tag distributions seem to be characteristic for folksonomies and how can we use these distributions effectively in information retrieval? What are the problems of indexing by using tags, especially regarding indexing photos and videos? How may we use factors of collaborative indexing for relevance ranking?
Digital libraries and human values: Human‐computer interaction meets social informatics
Authors: Fleischmann Kenneth R. 
Published: February 2009

AbstractDesigning and using digital libraries requires more than just technical expertise. Digital libraries face a growing number of challenges that cannot be tackled by solely technological means. For example, collections management involves tough choices about which materials to digitize given scarce resources, and which materials to discontinue in print form. Intellectual property can also come into play, especially for large digitization projects. For cataloging, the emergence of folksonomies threatens the authority of formal taxonomies. Digital libraries can encourage or discourage interaction between librarians and users, as in the case of reference services, as well as interaction among users, which may transform digital libraries into online communities. Finally, designers face challenges in ensuring that all users will be able to use digital libraries, including novice users and those with special needs. The digital age presents libraries with new challenges and opportunities. Will the library as a physical space be replaced by digital libraries, or merely augmented? Will libraries become irrelevant as users increasingly turn to commercial services to meet their information needs? Or, will libraries prove to be even more relevant and indispensable than ever in the digital age?
Magnetization transfer enhanced vascular‐space‐occupancy (MT‐VASO) functional MRI
Authors: Hua Jun , Donahue Manus J. , Zhao Jason M. , Grgac Ksenija , Huang Alan J. , Zhou Jinyuan , van Zijl Peter C.M. 
Published: February 2009

AbstractVascular‐space‐occupancy (VASO) MRI is a novel technique that uses blood signal nulling to detect blood volume alterations through changes in tissue signal. VASO has relatively low signal to noise ratio (SNR) because only 10–20% of tissue signal remain at the time of blood nulling. Here, it is shown that by adding a magnetization transfer (MT) prepulse it is possible to increase SNR either by attenuating the initial tissue magnetization when the MT pulse is placed before inversion, or, accelerating the recovery process when the pulse is applied after the inversion. To test whether the MT pulse would affect the blood nulling time in VASO, MT effects in blood were measured both ex vivo in a bovine blood phantom and in vivo in human brain. Such effects were found to be sufficiently small (< 2.5%) under a saturation power ≤ 3 μT, length = 500 ms, and frequency offset ≥40 ppm to allow use of the same nulling time. Subsequently, functional MRI experiments using MT‐VASO were performed in human visual cortex at 3 Tesla. The relative signal changes in MT‐VASO were of the same magnitude as in VASO, while the contrast to noise ratio (CNR) was enhanced by 44 ± 12% and 36 ± 11% respectively. Therefore, MT‐VASO should provide a means for increasing inherently low CNR in VASO experiments while preserving the CBV sensitivity. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Estimating amounts of iron oxide from gradient echo images
Authors: Dixon W. Thomas , Blezek Daniel J. , Lowery Lisa A. , Meyer Dan E. , Kulkarni Amit M. , Bales Brian C. , Petko Danielle L. , Foo Thomas K. 
Published: February 2009

AbstractRat legs directly injected with superparamagnetic iron oxide (SPIO) were studied by dual‐echo, gradient‐echo imaging. The amount of iron injected was estimated using a point dipole model for the SPIO injection site. Saturation magnetization of 6:1 PEG/amino modified silane‐coated iron oxide particles with 5‐ to 6‐nm core and 20–25 hydrodynamic diameter was ∼110 emu/g of iron. Estimates of the amount of iron injected made from signal void volumes surrounding SPIO centers yielded erroneous results varying with sample orientation in the scanner and echo time (TE). For example, a 10 μL, 3‐μg iron injection produced signal void volumes of 80 and 210 μL at TE of 9.8 and 25 ms, respectively, giving apparent iron contents of 6 ± 1 and 10 ± 2 μg respectively. A more effective approach uses the phase difference between two gradient recalled echo images. To estimate iron content, this approach fits the expected (3 cos2θ − 1)/|r|3 spatial phase distribution to the observed phase differences. Extraneous phase effects made fitting phase at a single TE ineffective. With the dual echo method, 18 independent estimates were 2.48 ± 0.26 μg std, independently of sample orientation. Estimates in empty control regions were −90 and −140 ng. A 1‐μg injection indicated 0.5, 1.2, and 1.2 μg. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Retest reliability of surface electromyography on the pelvic floor muscles
Authors: Grape Helena Hallencreutz , Dedering Åsa , Jonasson Aino Fianu 
Published: February 2009

AbstractAimsThe aim of the current study was to evaluate the retest reliability of repeated intravaginal surface electromyography (surface EMG) of the pelvic floor muscles in healthy women, who were able to perform correct pelvic floor muscle contractions.MethodsSeventeen nullipara women in the age of 20–35 years completed the measurements. The surface EMG was performed with the subjects in supine position with knees bent. The surface and ground electrodes were attached to a vaginal probe. A total of three test sessions were conducted, two on the same day with 30 minutes apart and a third 26–30 days later. Each test session consisted of three maximum contractions, 10 seconds hold and 10 seconds rest.ResultsAverage activity, peak, work and baseline showed good to high reliability (ICC = 0.83–0.96). The reliability was somewhat higher in‐between test session one and two compared with test session number three. Generally choosing the highest contraction in one test session resulted in a slightly higher ICC than taking an average result of all three contractions.ConclusionsThe current study shows that surface EMG is a reliable method of assessing pelvic floor muscle activity in healthy women. Neurourol. Urodynam. 28:395–399, 2009. © 2009 Wiley‐Liss, Inc.
Macromolecular nature of nanosheets of quasi‐TiO2 from (tetra‐isopropyl)orthotitanate modified by methacrylic acid
Authors: Wojciechowski Piotr , Halamus Tomasz , Sadowska Maja , Bobowska Izabela 
Published: February 2009

AbstractIn this paper we concentrate on the general behavior of oxotitanium hydrosol, which was earlier developed by us as a precursor of the TiO2 nanoparticles and nanocomposite. The oxotitanium hydrosol was synthesized by the chemical decomposition of a molecular complex of the methacrylic acid/(tetra‐isopropyl)orthotitanate (MAA/TIPT) by means of the hydrogen peroxide. The raw product chemical decomposition of MAA/TIPT is the colloidal suspension of the oxotitanium compound in the water. The oxotitanium compound was separated from hydrosol and identified on the basis of X‐ray and Raman spectroscopy investigations. The status of water in the hydrosol was also investigated by the Raman spectroscopy.The photophysical behaviors of the oxotitanium hydrosol on the basis of the light absorption and photoluminescence (PL) investigations are presented. The light absorption (260 nm) and PL emission (313 nm) allow us to identify the inorganic phase of hydrosol as nanosheets' crystallites of quasi‐TiO2. Macromolecular nature of nanosheets of quasi‐TiO2 was revealed only for a higher concentration solution of nanosheets' crystallites of quasi‐TiO2 at the hydrosol. A macromolecular nature of nanosheets of quasi‐TiO2 by the red shift of absorption edge and PL wavelength with increase in the concentration of the oxotitanium hydrosol as well as the formation of hydrogels and birefringence developed under an influence of mechanical shearing is evidenced. Copyright © 2009 John Wiley & Sons, Ltd.