bluuebunny/crossref_metadata_2025 huggingface dataset:
Constructing virtual hydraulic circuits using Flash
Authors: Gao Zhenguo , Wang Chunsheng
Published: February 2009

Virtual hydraulic circuits can be valuable complements to hydraulic circuit experiment education since that they can relieve the problem of lack of physical hydraulic experiment equipments. Flash is the most widely used software for creating plane animations for education. In this article, the process of constructing a virtual hydraulic circuit using Flash is demonstrated in detail by dividing the whole process into four steps: (1) designs the structure of the virtual hydraulic circuit, (2) creates virtual hydraulic component Flash symbols, (3) constructs the virtual hydraulic circuit Flash movie using the created virtual hydraulic component Flash symbols, and (4) synthesizes the mathematical models of the whole virtual hydraulic circuit, and implements numerical simulation algorithms using ActionScript language to drive the virtual hydraulic circuit according to the mathematical models. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 356–374, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20267
Cover Picture: Highly Water‐Soluble, Fluorescent, Conjugated Fluorene‐Based Glycopolymers with Poly(ethylene glycol)‐Tethered Spacers for Sensitive Detection of Escherichia coli (Chem. Eur. J. 10/2009)
Authors: Xue Cuihua , Velayudham Singaravelu , Johnson Steve , Saha Ratul , Smith Adrian , Brewer Wilbel , Murthy Pushpalatha , Bagley Susan T. , Liu Haiying
Published: February 2009

Detection of pathogenic Escherichia coli is of the utmost importance in the food industry, water and environmental quality control, and clinical diagnosis for health and safety reasons. In their Full Paper on page 2289 ff., H. Liu et al. describe glycopolymers, with the use of poly(ethylene glycol), as glycoside‐tethered spacers that offer the sensitive detection of E. coli, as a result of the significantly reduced steric binding hindrance of the polymeric carbohydrates to the bacterial pili.

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Diagnosis of renal osteodystrophy among chronic kidney disease patients
Authors: Khan Samina S. , Iraniha Mohammad R.
Published: February 2009

OBJECTIVE

The purpose of this review was to study the prevalence of and establish an association between biochemical markers and the underlying rate of bone turnover in renal osteodystrophy.

METHODS

Using the PubMed database, we undertook a systematic review of literature using studies that included bone histology in combination with serum biochemical markers among chronic kidney disease (CKD) patients, published between 1985 and 2007. Studies having at least 3 of 7 serum biochemical markers were chosen for this review.

RESULTS

Of the dialysis patients who were recipients of 1,701 bone biopsies, 41% had hyperparathyroid bone disease, 5% had osteomalacia, and 33% had adynamic bone disease. Among CKD patients not on dialysis, of a total of 1,316 bone biopsies, 34% had hyperparathyroid bone disease, 19% had osteomalacia, and 8% had adynamic bone disease. Dialysis patients who had high‐turnover bone disease compared with those with low bone turnover had significantly higher levels of parathyroid hormone, serum alkaline phosphatase, bone‐specific alkaline phosphatase, and osteocalcin. A similar relationship was observed among CKD patients not on dialysis. There was significant individual variation in bone turnover biochemical markers.

CONCLUSIONS

A combination of serum biochemical markers might predict underlying renal osteodystrophy better than would individual biochemical markers. A predictive model using bone histology and biochemical markers can be developed in the future.
Why can't Johnny remember the basic facts?
Authors: Baroody Arthur J. , Bajwa Neet Priya , Eiland Michael
Published: February 2009

Memorizing the basic number combinations, such as 9 + 7 = 16 and 16 − 9 = 7, is a punishing and insurmountable task for children with difficulties learning mathematics. Two perspectives on such learning lead to different conclusions about the primary source of this key learning difficulty. According to the conventional wisdom (the Passive Storage View), memorizing a basic fact is a simple form of learning—merely forming and strengthening an association between an expression and its answer. The two primary reasons this simple form of learning does not occur are inadequate practice or, in cases where adequate practice has been provided, a defect in the learner. According to the number sense perspective (Active Construction View), memorizing the basic combinations entails constructing a well‐structured or ‐connected body of knowledge that involves patterns, relations, algebraic rules, and automatic reasoning processes, as well as facts. In effect, fluency with the basic number combinations begins with and grows out of number sense. Aspects of number sense critical to such fluency begin to develop in the preschool years. According to the Active Construction View, the primary cause of problems with the basic combinations, especially among children at risk for or already experiencing learning difficulties, is the lack of opportunity to develop number sense during the preschool and early school years. © 2009 Wiley‐Liss, Inc. Dev Disabil Res Rev 2009;15:69–79.
Mathematical development in spina bifida
Authors: English Lianne H. , Barnes Marcia A. , Taylor Heather B. , Landry Susan H.
Published: February 2009

Spina bifida (SB) is a neural tube defect diagnosed before or at birth that is associated with a high incidence of math disability often without co‐occurring difficulties in reading. SB provides an interesting population within which to examine the development of mathematical abilities and disability across the lifespan and in relation to the deficits in visual‐spatial processing that are also associated with the disorder. An overview of math and its cognitive correlates in preschoolers, school‐age children and adults with SB is presented including the findings from a longitudinal study linking early executive functions in infancy to the development of later preschool and school age math skills. These findings are discussed in relation to socio‐historical perspectives on math education and implications for intervention and directions for further research are presented. © 2009 Wiley‐Liss, Inc. Dev Disabil Res Rev 2009;15:28–34.
Mathematical learning disability in girls with Turner syndrome: A challenge to defining MLD and its subtypes
Authors: Mazzocco Michèle M.M.
Published: February 2009

Turner syndrome is a common disorder with a prevalence of 1:2,500 live female births. Although not associated with mental retardation, there is an increased risk of learning difficulties in this population. In particular, mathematical learning difficulties among girls with Turner syndrome are prevalent, significant, and persistent. As such, the study of mathematical performance in girls with Turner syndrome presents opportunities to advance our knowledge of mathematics ability, disability, and disability subtypes. Moreover, the Turner syndrome phenotype illustrates the challenges faced when defining mathematical learning disability (MLD) and characterizing MLD subtypes because the cognitive phenotype is aligned with several proposed MLD subtypes. There is some evidence linking MLD in Turner syndrome with spatial deficits, with executive dysfunction, and with deficient numerosity skills. Yet there is also conflicting evidence as to whether any of these explanations underlies MLD in Turner syndrome. Most mathematical difficulties in girls with Turner syndrome, as a group, occur on timed tests or on complex problems. On untimed tests, achievement test scores may be age appropriate. Therefore, the inclusion of MLD in the Turner syndrome cognitive phenotype reminds us that we cannot rule out MLD solely on the basis of performance on an untimed calculations subtest, and it poses a challenge to the widespread practice in which many researchers engage, that is, defining MLD on the basis of broad mathematics achievement test outcomes. © 2009 Wiley‐Liss, Inc. Dev Disabil Res Rev 2009;15:35–44.
Principal component analysis for compositional data with outliers
Authors: Filzmoser Peter , Hron Karel , Reimann Clemens
Published: February 2009

Compositional data (almost all data in geochemistry) are closed data, that is they usually sum up to a constant (e.g. weight percent, wt.%) and carry only relative information. Thus, the covariance structure of compositional data is strongly biased and results of many multivariate techniques become doubtful without a proper transformation of the data. The centred logratio transformation (clr) is often used to open closed data. However the transformed data do not have full rank following a logratio transformation and cannot be used for robust multivariate techniques like principal component analysis (PCA). Here we propose to use the isometric logratio transformation (ilr) instead. However, the ilr transformation has the disadvantage that the resulting new variables are no longer directly interpretable in terms of the originally entered variables. Here we propose a technique how the resulting scores and loadings of a robust PCA on ilr transformed data can be back‐transformed and interpreted. The procedure is demonstrated using a real data set from regional geochemistry and compared to results from non‐transformed and non‐robust versions of PCA. It turns out that the procedure using ilr‐transformed data and robust PCA delivers superior results to all other approaches. The examples demonstrate that due to the compositional nature of geochemical data PCA should not be carried out without an appropriate transformation. Furthermore a robust approach is preferable if the dataset contains outliers. Copyright © 2009 John Wiley & Sons, Ltd.
Extreme limit distribution of truncated models for daily rainfall
Authors: Hernández Aracelis , Guenni Lelys , Sansó Bruno
Published: February 2009

We propose truncated and power‐transformed (TPT) models for daily rainfall and we derive the generalized extreme value (GEV) limit distributions for these models. We find that these limit distributions belong to the domain of attraction of the Fréchet family when the parent distribution of the daily values is a TPT t‐Student model. In this case, the shape parameter of the limiting GEV model depends on the degrees of freedom and the power transformation parameter. When the parent distribution of the daily values is a TPT Normal model, the limiting GEV model is independent of the parameters of the parent model. We perform a detailed inference and predictive analysis to verify these theoretical results using a Bayesian approach. Markov Chain Monte Carlo methods (MCMC) were used to estimate the posterior distribution of the parameters of the t‐Student model for daily rainfall on one hand, and to estimate the posterior distribution of the parameters of the GEV model for the annual maxima on the other hand. Numerical results are presented for two locations: Maiquetía (Vargas State), and La Mariposa (Miranda State), Venezuela. Simulations from the predictive distribution of the daily values suggest a good approximation between the extreme distribution of the TPT t‐Student model and the Fréchet model found by standard extreme value limit theory. Copyright © 2009 John Wiley & Sons, Ltd.
Membrane‐Less Biofuel Cell Based on Cellobiose Dehydrogenase (Anode)/Laccase (Cathode) WiredviaSpecific Os‐Redox Polymers
Authors: Stoica L. , Dimcheva N. , Ackermann Y. , Karnicka K. , Guschin D. A. , Kulesza P. J. , Rogalski J. , Haltrich D. , Ludwig R. , Gorton L. , Schuhmann W.
Published: February 2009

A membrane‐free biofuel cell (BFC) is reported based on enzymes wired to graphite electrodes by means of Os‐complex modified redox polymers. For the anode cellobiose dehydrogenase (CDH) is used as a biocatalyst whereas for the cathode a laccase was applied. This laccase is a high‐potential laccase and hence able to reduce O2to H2O at a formal potential higher than +500 mVversusAg/AgCl. In order to establish efficient electrochemical contact between the enzymes and graphite electrodes electrodeposition polymers containing Os‐complex with specifically designed monomer compositions and formal potentials of the coordinatively bound Os‐complex were synthesised and used to wire the enzymes to the electrodes. The newly designed CDH/Os‐redox polymer anode was characterised at different pH values and optimised with respect to the nature of the polymer and the enzyme‐to‐polymer ratio. The resulting BFC was evaluated running on β‐lactose as a fuel and air/O2as an oxidising agent. The power output, the maximum current density and the electromotor force (Eemf) were found to be affected by the pH value, resulting in a maximum power output of 1.9 μW cm–2reached at pH 4.3, a maximum current density of about 13 μA cm–2at pH 3.5, and the highestEemfapproaching 600 mV at pH 4.0.
Hemoproteins in Design of Biofuel Cells
Authors: Ramanavicius A. , Ramanaviciene A.
Published: February 2009

Direct electron transfer (DET) is a unique feature of some enzymes. The possibility of DET between enzymes and the electrode surface could pave the way for superior reagentless, noncompartmentised, mediator‐free biofuel cells, as it obviates the need for mediators and allows an efficient transduction of the electrical current. DET is highly beneficial in the development of enzymatic and microbial biofuel cells. In this review article, hemoproteins, which are able to directly transfer electrons to the surfaces of conducting supports, are briefly overviewed and characterised. The main focus is laid on the application of heme‐c containing enzymes in biofuel cell design. Some historical steps and recent developments in biofuel cell design are presented in this article. Various designs of biofuel cells are overviewed. Possible applications of biofuel cells are presented and/or predicted and discussed. Problems and challenges in biofuel cell design and application are identified while possible directions to solve recent problems in biofuel cell development are discussed. The application of enzymatic biofuel cells as model systems and tools for advanced study of bioelectronics' properties of enzymes is predicted.
Simultaneous expansions of microRNAs and protein‐coding genes by gene/genome duplications in early vertebrates
Authors: Gu Xun , Su Zhixi , Huang Yong
Published: February 2009

Does miRNAs underlie the origin of organismal complexity in vertebrates? The current controversy is focused on whether the inventory of vertebrate miRNAs can be explained by the classical two‐round genome duplications. We estimate the age distribution of vertebrate miRNA duplication events, showing the evolutionary scenario that gene/genome duplications in the early stage of vertebrates may expand the protein‐encoding genes and miRNAs simultaneously. We further speculate that genetically lying behind the evolution of vertebrate complexity may be the proteome doubling and alterations of the epigenetic (including miRNA) machinery. J. Exp. Zool. (Mol. Dev. Evol.) 312B:164–170, 2009. © 2009 Wiley‐Liss, Inc.
The phyllolepid placoderm Cowralepis mclachlani: Insights into the evolution of feeding mechanisms in jawed vertebrates
Authors: Carr Robert K. , Johanson Zerina , Ritchie Alex
Published: February 2009

Remarkably preserved specimens of Cowralepis mclachlani Ritchie, 2005 (Proc Linn Soc NSW 126:215–259) (Phyllolepida, Placodermi) represent a unique ontogenetic sequence adding to our understanding of anatomy, function, and phylogeny among basal jawed vertebrates (gnathostomes). A systematic review demonstrates that the Phyllolepida are a subgroup of the Arthrodira. Consideration of visceral and neurocranial characters supports the hypothesis that placoderms are the sister group to remaining gnathostomes. Placoderms possess, as adult plesiomorphic features, a number of characters that are only seen in the development of extant gnathostomes—a peramorphic shift relative to placoderms. Developmental evidence in vertebrates leads to a revised polarity of character transitions. These include 1) hyomandibula‐neurocranium and ventral parachordal‐palatoquadrate articulations (vertebrate synapomorphies); 2) jointed pharynx, paired basibranchials, anterior ethmoidal‐palatoquadrate articulation, short trabeculae cranii, and anterior and posterior neurocranial fissures (gnathostome synapomorphies); and 3) fused basibranchials, dorsal palatoquadrate‐neurocranium articulation, loss of the anterior neurocranial fissure, elongated trabeculae cranii, and transfer of the ventral parachordal‐palatoquadrate articulation to the trabeculae (crown group gnathostomes). The level of preservation in C. mclachlani provides the basis for a reinterpretation of phyllolepid anatomy and function. Cowralepis mclachlani possesses paired basibranchials allowing the reinterpretation of the visceral skeleton in other placoderms. Mandible depression in C. mclachlani follows an osteichthyan pattern and the ventral visceral skeleton acts as a functional unit. Evidence for hypobranchial musculature demonstrates the neural crest origin of the basibranchials and that Cowralepis was a suction feeder. Finally, the position of the visceral skeleton relative to the neurocranium in placoderms parallels the condition in selachians and osteichthyans, but differs in the elongation of the occiput. The cucullaris fossa of placoderms (interpreted as a site of muscle attachment) is shown to represent, in part, the parabranchial chamber. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.
Osteogenic potential and responsiveness to leptin of mesenchymal stem cells between postmenopausal women with osteoarthritis and osteoporosis
Authors: Zhang Zi‐Ming , Jiang Lei‐Sheng , Jiang Sheng‐Dan , Dai Li‐Yang
Published: February 2009

The aim of this study was to compare the osteogenic potential and responsiveness to leptin of mesenchymal stem cells (MSCs) from bone marrow between postmenopausal women with osteoarthritis (OA) and osteoporosis (OP). MSCs of the proximal femur from OA and OP donors were cultured under control and different experimental mediums. After verifying the availability of primary cells, their osteogenic potential and responsiveness to leptin were compared between two groups. Similar patterns of cell growth were shown in both OA and OP groups. However, after the sixth passage, the viability of undifferentiated cells decreased more in OP than in OA donors. Under the same osteogenic supplements condition, the mRNA expression of osteogenesis‐specific genes, osteocalcin (OC) and alkaline phosphatase (ALP) were higher in OA group. Comparison of bone matrix mineralization was parallel to that of mRNA expression. The level of bone‐specific ALP (BAP) was higher in cells from donors with OA, whereas osteoprotegerin (OPG) was higher in OP group. This difference in BAP expression proved to be insignificant after the administration of leptin. Although leptin upregulated the expression of OPG, a significant difference still existed between OA and OP. In conclusion, differential osteogenic potential and responsiveness to leptin of MSCs were noted between postmenopausal women with OA and OP. Differential biological behavior of MSCs seems to be partly related to the different distribution of bone mass between OA and OP populations. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 1067–1073, 2009
Nutrient content and yield in relation to top breakover in onion developed from greenhouse‐grown transplants
Authors: Russo Vincent M
Published: February 2009

BACKGROUND: Onions (Allium cepa L.) generally are harvested based on percentage of tops broken over. Since plant metabolism changes over time, percentage of tops broken over may be used to determine a harvest time to deliver marketable bulbs with the best nutrient content.

RESULTS: The cultivars Candy and Texas Grano 1015 Y were harvested at 10%, 20%, 30%, 40% and 50% breakover in 2006 and 2007. Larger and heavier bulbs were produced by Candy and in 2006, the year with near‐normal precipitation. There was little difference in bulb size and weight due to percent breakover. Contents of chemical moieties in bulbs were affected by year, with the majority of values being higher in 2006, and there were either no differences due to cultivar, or where differences were found nitrate‐N, phosphate and sulfate contents were lower in Candy. Soluble solids content was lower in 2006 and higher in Candy. Content of nitrogen and phosphorous in a Kjeldahl digest, nitrate‐N, phosphate, potassium and sulfate were either linearly or quadratically distributed over percent breakover. Nitrite‐N, calcium, magnesium, sodium and soluble solids were randomly distributed over percent breakover. Bulb size and weight did not change from the 20% breakover point, and most of the chemical moieties analyzed, with the exception of nitrate‐ and nitrite‐N values, were highest below the 30% breakover.

CONCLUSION: Harvest occurring soon after breakover begins could be beneficial in terms of nutrient content without loss of bulb size or weight. Copyright © 2009 Society of Chemical Industry
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

In 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

In 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

Several 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

ABA 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

A 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

Reversible 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

The 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

Modeling 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

Different 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

Due 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

4‐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

In 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

Designing 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

Vascular‐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

Rat 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

Aims

The 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.

Methods

Seventeen 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.

Results

Average 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.

Conclusions

The 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

In 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.
Stem cell factor–KIT signalling plays a pivotal role in regulating pigmentation in mammalian hair
Authors: Hachiya Akira , Sriwiriyanont Penkanok , Kobayashi Takeshi , Nagasawa Azumi , Yoshida Hiroshi , Ohuchi Atsushi , Kitahara Takashi , Visscher Marty O , Takema Yoshinori , Tsuboi Ryoji , Boissy Raymond E
Published: February 2009

Hair greying is one of the most distinct but least comprehended features of senescence. The signalling of stem cell factor (SCF) and its receptor KIT has been documented to regulate essential roles in the maintenance of embryonic melanocyte lineages and postnatal cutaneous melanogenesis, although little is known about its detailed mechanisms in postnatal hair pigmentation. To address this, anagen human hair follicles and C57BL/6 murine pelage were analysed in this study. Molecular biological analyses of murine follicular skin indicated a significant increase of membrane‐bound SCF expression, reaching its peak 8–16 days after anagen induction in concert with the escalation of cutaneous tyrosinase activity and corresponding pigmentation. Administration of KIT–neutralizing antibody abolished MITF and tyrosinase expressions, resulting in a reversible hair depigmentation in murine regenerated hair and human hair organ culture. Quantitative RT‐PCR of human hair follicles indicated that KIT expression as well as the expression of several melanogenic factors, including MITF, was significantly lower in unpigmented than in pigmented follicles. Taken together, these data revealed a pivotal role of SCF–KIT signalling in the maintenance of human hair follicle melanogenesis during the anagen cycle and its involvement in physiological ageing of the hair follicle pigmentary unit. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Splenectomy in hereditary spherocytosis: Review of 1,657 patients and application of the pediatric quality indicators
Authors: Abdullah Fizan , Zhang Yiyi , Camp Melissa , Rossberg Mark I. , Bathurst Melinda A. , Colombani Paul M. , Casella James F. , Nabaweesi Rosemary , Chang David C.
Published: February 2009

Objective

The objective of the present study is to profile the outcome and safety of pediatric patients undergoing splenectomy with hereditary spherocytosis (HS) using a nationwide sample and the Agency for Healthcare Research and Quality (AHRQ) Pediatric Quality Indicators (PDIs).

Patients and Methods

A retrospective cross‐sectional descriptive analysis of a non‐overlapping combination of the National Inpatient Sample (NIS), and Kids' Inpatient Database (KID) databases (1988–2004) were performed. These combined databases contain information from nearly 93 million discharges in the United States. Children with an age at admission of <18 years of age and HS (ICD‐9 diagnosis code of 282.0) who underwent total splenectomy (ICD‐9 procedure code of 41.5) were identified. Variables of gender, race, co‐existing diagnoses, hospital type, and charges adjusted to 2006 dollars, length of stay, inpatient mortality, and complications were collected. PDIs were identified for each patient by linking the data obtained from the NIS and KID databases with the PDIs using the AHRQ Quality Indicators Wizard.

Results

Splenectomy for HS was associated with low morbidity and mortality. Accompanying cholecystectomy and/or appendectomy appeared to be safely performed at the same operation. Of the 13 PDIs identified by AHRQ as potentially avoidable adverse events, none were observed to occur in more than 1% of the patients.

Conclusions

Based on the results of this study, splenectomy in patients with HS appears safe and to result in a minimal number of potentially preventable complications as identified by the AHRQ PDIs. We have successfully demonstrated use of the indicators to aid in the analysis of a specific surgical procedure within a subset of the pediatric population. Pediatr Blood Cancer 2009;52:834–837. © 2009 Wiley‐Liss, Inc.