bluuebunny/crossref_metadata_2025 huggingface dataset:
Target Atmospheric CO: Where Should Humanity Aim?
Authors: Hansen James , Sato Makiko , Kharecha Pushker , Beerling David , Berner Robert , Masson-Delmotte Valerie , Pagani Mark , Raymo Maureen , Royer Dana L. , Zachos James C.
Published: November 2008

Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO was the main cause of a cooling trend that began 50 million years ago, the planet being nearly ice-free until CO fell to 450 ± 100 ppm; barring prompt policy changes, that critical level will be passed, in the opposite direction, within decades. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less than that. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.
Deflation: Are We Still Sure "It" Cannot Happen Here?
Authors: Dolan Edwin
Published: November 2008

In 2002, the possibility of deflation in the United States looked "remote indeed" to newly appointed Fed Governor Ben Bernanke. In light of recent events, Edwin Dolan wonders if we can still be so sure.
History Matters: United States Policy and Indigenous Early Childhood Intervention
Authors: Niles Michael D. , Byers Lisa G.
Published: November 2008

This article discusses the degree to which early childhood practitioners in the United States attend to cultural differences and social injustice in their pedagogy, with a particular reference to indigenous peoples. The article has three major sections. The first describes an indigenous perspective regarding ‘improvement’ and ‘quality’ with respect to early childhood programs. Included is a review of United States policy developments regarding indigenous peoples (including an examination of relevant aspects of the Bureau of Indian Affairs) and a discussion of the impact of those policies on indigenous families. The second section discusses the impact of contemporary early childhood policies and practices on indigenous communities. The third section is a review of the dominant research literature and theoretical beliefs.
Agency in Early Childhood Learning and Development in Cameroon
Authors: Nsamenang A. Bame
Published: November 2008

This article focuses on agency, as a natural disposition in children to be active and participative. Africa's parenting attitudes and education in African family traditions encourage and foster children's responsible agency in family life, cultural and economic activities, and their own developmental learning from an early, especially within the peer culture. It is amazing that in an era of accentuating efforts to understand and actualize the UNCRC provisions on children's citizenship and participation, international advocacy persists in stigmatizing as child labor the centuries-old productive agency of Africa's children and youth, which disables almost 70 percent of the continent's population, instead of working to enhance and learn from it. The article critiques the conceptual developmental and core rights issues pertaining to children's agency, substantiating the discourse with illustrative impressions on the changing but ‘normative’ child agency in family traditions in Cameroon.
Childhood Labor in India: Issues and Complexities
Authors: Viruru Radhika
Published: November 2008

It is estimated that more than 12 million children in India under the age of 14 engage in paid labor at least part time, due mostly to economic reasons. Dominant discourses about childhood however conceptualize childhood labor not only as unethical but as exploitation. This article explored will the tensions between Western notions of childhood (within which paid labor is considered taboo) and the realities of children's lives in India, arguing that childhood labor must be contextualized and understood not only as a colonial legacy but also as part of its socio-cultural context. The author argues that separating children from the world of work fosters a culture of childhood that emphasizes entitlement over participation and privileges the rights of the consumer over children's rights as citizens.
Teaching Early Childhood Teacher Candidates How to Assess Children's Inquiry Skills in Science Learning
Authors: Lee Joohi , Yoon Ji Yoon
Published: November 2008

This article presents pragmatic information on teaching early childhood teacher candidates how to assess children's inquiry process skills. The authors list three important steps in choosing inquiry skills. They generated behavioral indicators for each inquiry skill, and designed an assessment rubric using number grading or a satisfactory/unsatisfactory rubric system.
Green’s function for an electron model with a plane wave
Authors: Ould Lahoucine Hassen , Chetouani Lyazid
Published: November 2008

The Green function for a Dirac particle subject to a plane wave field is constructed according to the path integral approach and the Barut’s electron model. Then it is exactly determined after having fixed a matrix U chosen so that the equations of motion are those of a free particle, and by using the properties of the plane wave and also with some shifts.
Remote Sensing Monitoring of Changes in Soil Salinity: A Case Study in Inner Mongolia, China
Authors: Wu Jingwei , Vincent Bernard , Yang Jinzhong , Bouarfa Sami , Vidal Alain
Published: November 2008

This study used archived remote sensing images to depict the history of changes in soil salinity in the Hetao Irrigation District in Inner Mongolia, China, with the purpose of linking these changes with land and water management practices and to draw lessons for salinity control. Most data came from LANDSAT satellite images taken in 1973, 1977, 1988, 1991, 1996, 2001, and 2006. In these years salt-affected areas were detected using a normal supervised classification method. Corresponding cropped areas were detected from NVDI (Normalized Difference Vegetation Index) values using an unsupervised method. Field samples and agricultural statistics were used to estimate the accuracy of the classification. Historical data concerning irrigation/drainage and the groundwater table were used to analyze the relation between changes in soil salinity and land and water management practices. Results showed that: (1) the overall accuracy of remote sensing in detecting soil salinity was 90.2%, and in detecting cropped area, 98%; (2) the installation/innovation of the drainage system did help to control salinity; and (3) a low ratio of cropped land helped control salinity in the Hetao Irrigation District. These findings suggest that remote sensing is a useful tool to detect soil salinity and has potential in evaluating and improving land and water management practices.
Recent Progress in Nucleic Acid Aptamer-Based Biosensors and Bioassays
Authors: Mok Wendy , Li Yingfu
Published: November 2008

As the key constituents of the genetic code, the importance of nucleic acids to life has long been appreciated. Despite being composed of only four structurally similar nucleotides, single-stranded nucleic acids, as in single-stranded DNAs and RNAs, can fold into distinct three-dimensional shapes due to specific intramolecular interactions and carry out functions beyond serving as templates for protein synthesis. These functional nucleic acids (FNAs) can catalyze chemical reactions, regulate gene expression, and recognize target molecules. Aptamers, whose name is derived from the Latin word aptus meaning “to fit”, are oligonucleotides that can bind their target ligands with high affinity and specificity. Since aptamers exist in nature but can also be artificially isolated from pools of random nucleic acids through a process called in vitro selection, they can potentially bind a diverse array of compounds. In this review, we will discuss the research that is being done to develop aptamers against various biomolecules, the progress in engineering biosensors by coupling aptamers to signal transducers, and the prospect of employing these sensors for a range of chemical and biological applications. Advances in aptamer technology emphasizes that nucleic acids are not only the fundamental molecules of life, they can also serve as research tools to enhance our understanding of life. The possibility of using aptamer-based tools in drug discovery and the identification of infectious agents can ultimately augment our quality of life.
Electrochemical Performance of a Carbon Nanotube/La-Doped TiO2 Nanocomposite and its Use for Preparation of an Electrochemical Nicotinic Acid Sensor
Authors: Wu Jing , Liu Hanxing , Lin Zhidong
Published: November 2008

A carbon nanotube/La-doped TiO2 (La-TiO2) nanocomposite (CLTN) was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM) images show that the La-TiO2 distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to form a CLTN paste for the CLTN paste electrode (CLTNPE). The electrochemical characteristics of CLTNPE were compared with that of conventional carbon electrodes such as the carbon paste electrode (CPE) and glass carbon electrode (GC). The CLTNPE exhibits electrochemical activity and was used to investigate the electrochemistry of nicotinic acid (NA). The modified electrode has a strong electrocatalytic effect on the redox of NA. The cyclic voltammetry (CV) redox potential of NA at the CLTNPE is 320 mV. The oxidation process of NA on the CLTNPE is pH dependent. A sensitive chronoamperometric response for NA was obtained covering a linear range from 1.0×10-6 mol·L-1 to 1.2×10-4 mol·L-1, with a detection limit of 2.7×10-7 mol·L-1. The NA sensor displays a remarkable sensitivity and stability. The mean recovery of NA in the human urine is 101.8%, with a mean variation coefficient (RSD) of 2.6%.
Determination of Vitamin C (Ascorbic Acid) Using High Performance Liquid Chromatography Coupled with Electrochemical Detection
Authors: Gazdik Zbynek , Zitka Ondrej , Petrlova Jitka , Adam Vojtech , Zehnalek Josef , Horna Ales , Reznicek Vojtech , Beklova Miroslava , Kizek Rene
Published: November 2008

Vitamin C (ascorbic acid, ascorbate, AA) is a water soluble organic compound that participates in many biological processes. The main aim of this paper was to utilize two electrochemical detectors (amperometric – Coulouchem III and coulometric – CoulArray) coupled with flow injection analysis for the detection of ascorbic acid. Primarily, we optimized the experimental conditions. The optimized conditions were as follows: detector potential 100 mV, temperature 25 °C, mobile phase 0.09% TFA:ACN, 3:97 (v/v) and flow rate 0.13 mL·min-1. The tangents of the calibration curves were 0.3788 for the coulometric method and 0.0136 for the amperometric one. The tangent of the calibration curve measured by the coulometric detector was almost 30 times higher than the tangent measured by the amperometric detector. Consequently, we coupled a CoulArray electrochemical detector with high performance liquid chromatography and estimated the detection limit for AA as 90 nM (450 fmol per 5 μL injection). The method was used for the determination of vitamin C in a pharmaceutical preparations (98 ± 2 mg per tablet), in oranges (Citrus aurantium) (varied from 30 to 56 mg/100 g fresh weight), in apples (Malus sp.) (varied from 11 to 19 mg/100 g fresh weight), and in human blood serum (varied from 38 to 78 μM). The recoveries were also determined.
Development of a Medical-text Parsing Algorithm Based on Character Adjacent Probability Distribution for Japanese Radiology Reports
Authors: Terae S. , Uesugi M. , Ogasawara K. , Sakurai T. , Nishimoto N.
Published: November 2008

Objectives:
The objectives of this study were to investigate the transitional probability distribution of medical term boundaries between characters and to develop a parsing algorithm specifically for medical texts.

Methods:
Medical terms in Japanese computed tomography (CT) reports were identified using the ChaSen morphological analysis system. MeSH-based medical terms (51,385 entries), obtained from the metathesaurus in the Unified Medical Language System (UMLS, 2005AA), were added as a medical dictionary for ChaSen. A radiographer corrected the set of results containing 300 parsed CT reports. In addition, two radiologists checked the medical term parsing of 200 CT sentences.

Results:
We obtained modified inter-annotator agreement scores for the text corrected by the radiologists. We retrieved the transitional probability as the conditional probability of a uni-gram, bi-gram, and tri-gram. The highest transitional probability P(Ci | Ci - 2*Ci - 1) was 1.00. For an example of anatomical location, the term “pulmonary hilum” was parsed as a tri-gram.

Conclusions:
Retrieval of transitional probability will improve the accuracy of parsing compound medical terms.
Modification of polysulfone membranes via surface‐initiated atom transfer radical polymerization and their antifouling properties
Authors: Li Liang , Yan Guoping , Wu Jiangyu
Published: November 2008

Surface‐initiated atom transfer radical polymerization (ATRP) was used to tailor the functionality of polysulfone (PSF) membranes. A simple one‐step method for the chloromethylation of PSF under mild conditions was used to introduce surface benzyl chloride groups as active ATRP initiators. Covalently tethered hydrophilic polymer brushes of poly(ethylene glycol)monomethacrylate and 2‐hydroxyethyl methacrylate and their block copolymer brushes were prepared via surface‐initiated ATRP from the chloromethylated PSF surfaces. A kinetic study revealed that the chain growth from the membranes was consistent with a controlled process. X‐ray photoelectron spectroscopy was used to characterize the surface‐modified membrane after each modification stage. Protein adsorption experiments revealed substantial antifouling properties of the grafted PSF membranes in comparison with the those of the pristine PSF surface. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Copolymerization of ethylene and cyclopentene with the Phillips CrOx/SiO2 catalyst in the presence of an aluminum alkyl cocatalyst
Authors: Xia Wei , Tonosaki Kiwamu , Taniike Toshiaki , Terano Minoru , Fujitani Tadahiro , Liu Boping
Published: November 2008

The Phillips CrOx/SiO2 catalyst is an important industrial catalyst for ethylene polymerization. However, understanding of the state of active sites and chain propagation mechanisms concerning the Phillips catalyst is still waiting for conclusive evidence. In this work, the Phillips CrOx/SiO2 catalyst, having been calcined, was used for investigating the copolymerization of ethylene and cyclopentene in the presence of triethylaluminum as a cocatalyst for the first time. The microstructures of the polymers were investigated with 13C‐NMR and gel permeation chromatography methods. Because of the absence of internal double bond (CC) in the copolymer main chain, the ring‐opening metathesis polymerization of cyclopentene was excluded during the copolymerization stage of ethylene and cyclopentene. Also, the 1,2‐insertion and 1,3‐insertion of cyclopentene into the polyethylene main chain were confirmed. This evidence strongly implies that CrC species may not be the active sites for chain propagation; instead, the CrC active site model under the Cossee–Arlman chain propagation mechanism may be responsible for the chain propagation during the normal polymerization period. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of pH and temperature on the sorption of sodium dodecyl sulfate by cellulose acetate/polyaniline blend membranes
Authors: Pereira R. F. P. , Cerqueira D. A. , Valente A. J. M. , Polishchuk A. Y. , Burrows H. D. , Lobo V. M. M.
Published: November 2008

Cellulose acetate/polyaniline (PANi) blends show a selective response to the presence of sodium dodecyl sulfate (SDS). Such detection can be monitored by visible absorption spectroscopy. In this article, we show how this is dependent on the pH and temperature. At pH 2, the redshift of the maximum absorbance wavelength of blend films is essentially dependent on hydrochloric acid; however, at pH 3, this effect clearly decreases, and at pH values between 4 and 6, the alteration of the blend color depends only on SDS. The selective detection of SDS is faster with a higher percentage of PANi in the blend. At 25°C, the mechanism of sorption is essentially Fickian for short times, but this changes at higher temperatures, and at temperatures of 40°C and higher, the sorption kinetics show an initial time lag in which no visible response from the blend to SDS is detected. The response rate of blends to SDS detection increases with the temperature and PANi content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Facile synthesis of functional silica/polymer composite materials and hydrophilic hollow polymer microspheres
Authors: Liu Guangyu , Zhang Han , Yang Xinlin , Wang Yongmei
Published: November 2008

Monodisperse functional silica/polymer core‐shell composite materials with silica as core and hydrophilic polymer with various functional groups, such as amide, carboxylic acid, hydroxyl, and pyridyl group, as shell were facilely prepared by a two‐stage reaction, in which the silica core with diameter of 179 nm was synthesized in the first‐stage reaction according to the Stöber method. The functional polymer shell was then encapsulated onto the silica core by distillation–precipitation copolymerization of N,N′‐methylenebisacrylamide (MBAAm) as crosslinker and hydrophilic comonomers with different functional groups, including N‐isopropylacrylamide, methacrylic acid, 2‐hydroxyethyl methacrylate, and 4‐vinylpyridine, in neat acetonitrile with 2,2′‐azobisisobutyronitrile as initiator. The encapsulation of the functional polymer shell onto the silica core particles was driven by the hydrogen‐bonding interaction between the hydroxyl group on the surface of silica core and the amide unit of MBAAm crosslinker as well as the functional groups of the comonomers during the distillation–precipitation polymerization without modification of the silica surface in absence of any stabilizer or surfactant. The shell thickness of the composite can be controlled by MBAAm fraction in the monomer feed during the polymerization. Hydrophilic hollow polymer microspheres with various functional groups, including amide, carboxylic acid, hydroxyl, and pyridyl, were further developed after selective removal of silica core with hydrofluoric acid. The functional core‐shell silica/polymer composites and the corresponding functional hollow microspheres were characterized with transmission electron microscopy, Fourier transform infrared spectra, and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Modification of the molar anionic charge density of acetone–formaldehyde–sulfite dispersant to improve adsorption behavior and effectiveness in the presence of CaAMPS®‐co‐NNDMA cement fluid loss polymer
Authors: Plank Johann , Dugonjić‐Bilić Fatima , Lummer Nils Recalde
Published: November 2008

Sulfonated aldol polycondensates were synthesized from acetone, formaldehyde, and different amounts of sodium sulfite, resulting in polymers with varying degrees of sulfonation (DS). The anionic charge amount of these macromolecules measured by polyelectrolyte titration decreased with lower DS. The effectiveness of the acetone–formaldehyde–sulfite (AFS) polycondensates as cement dispersant was found to depend on the amount of polymer adsorbed on cement. AFS adsorption decreases with lower DS. Interaction and compatibility between AFS and CaAMPS®‐co‐NNDMA fluid loss additive was studied by formulating binary additive systems composed of one of the modified AFS polymers and CaAMPS‐co‐NNDMA. At high DS, AFS adsorbs strongly and prevents CaAMPS‐co‐NNDMA from adsorbing in sufficient amounts on the cement surface. The result is poor fluid loss control of the cement slurry. AFS polymers with lower DS, however, allow simultaneous adsorption of both polymers in sufficient quantities to provide good fluid loss control and low rheology at the same time. Thus, effectiveness of both additives was retained. Obviously, effectiveness of such multi‐admixture systems depends on the adjustment of the adsorption behavior of the individual components relative to each other. Molar anionic charge density of the polymers was found to be a major parameter influencing their relative adsorption behavior. The AFS polymer with DS = 0.2 possesses a molar anionic charge density comparable to CaAMPS‐co‐NNDMA. Thus, when admixtures with similar molar anionic charge densities are used, the performance of one component is not negatively influenced by the other. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polymeric Salphen‐phthalocyanine dinuclear metal complexes for activation of molecular oxygen
Authors: Wang Rong‐Min , Hao Er‐Xia , Shen Guo‐Rui , He Yu‐Feng , Lei Zi‐Qiang
Published: November 2008

The polymeric Salphen Schiff base‐phthalocyanine Co‐Cu dinuclear metal complex (PSalphenCo‐PcCu) was designed and synthesized through interfacial condensation polymerization. The new sheet polymeric dinuclear metal complex has been characterized by IR spectra, UV‐visible spectra, scanning electron microscopy with energy dispersive X‐ray analysis and thermogravimetry analysis. Its catalytic activity for activation of molecular oxygen was investigated by using cumene as substrate without any additive in mild condition. The aerobic oxidation of cumene catalyzed by PSalphenCo‐PcCu proved to be a simple and efficient method for obtaining cumene hydroperoxide in a high selectivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A new approach for detecting scientific specialties from raw cocitation networks
Authors: Wallace Matthew L. , Gingras Yves , Duhon Russell
Published: November 2008

We use a technique recently developed by V. Blondel, J.‐L. Guillaume, R. Lambiotte, and E. Lefebvre (2008) to detect scientific specialties from author cocitation networks. This algorithm has distinct advantages over most previous methods used to obtain cocitation “clusters” since it avoids the use of similarity measures, relies entirely on the topology of the weighted network, and can be applied to relatively large networks. Most importantly, it requires no subjective interpretation of the cocitation data or of the communities found. Using two examples, we show that the resulting specialties are the smallest coherent “groups” of researchers (within a hierarchy of cluster sizes) and can thus be identified unambiguously. Furthermore, we confirm that these communities are indeed representative of what we know about the structure of a given scientific discipline and that as specialties, they can be accurately characterized by a few keywords (from the publication titles). We argue that this robust and efficient algorithm is particularly well‐suited to cocitation networks and that the results generated can be of great use to researchers studying various facets of the structure and evolution of science.
Net energy: still a (mostly) irrelevant, misleading and dangerous metric
Authors: Dale Bruce E.
Published: November 2008

Classical net energy analysis does not define “net energy” as Dr. Pimentel has defined it. Classical net energy analysis has limited value. Dr. Pimentel's use of net energy to attack biofuels is irrelevant, misleading and even dangerous in a world struggling to find alternatives to petroleum.

© 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Looking beyond land use change issues
Authors: Berndes Göran
Published: November 2008

Policy‐makers have to respond to concerns about land use change. Copyright © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Response to Dr. Poldy's questions in this issue
Authors: Dale Bruce E.
Published: November 2008

Some have written to this journal to take issue with my characterization of net energy as an irrelevant and misleading metric for fuel performance. We welcome open discussion of controversial issues related to biofuels in this journal and so have invited Dr. Franz Poldy (CSIRO Sustainable Ecosystems, Australia) to write a defense of net energy and critique of my earlier article. Since I am the Editor in Chief, I get to have the last word, and have briefly responded to Dr. Poldy's article. It is apparent that Dr. Poldy uses a different definition of net energy than does Dr. Pimentel. We invite the readers to consider the arguments and make up their own minds.

© 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Mechanism of cellulase reaction on pure cellulosic substrates
Authors: Gupta Rajesh , Lee Y.Y.
Published: November 2008

Cellulase reaction mechanism was investigated with the use of following pure cellulosic substrates: Microcrystalline cellulose (Avicel), α‐cellulose (Sigma), filter paper, cotton, and non‐crystalline cellulose (NCC). NCC is amorphous cellulose prepared in our laboratory by treatment with concentrated sulfuric acid. When hydrolyzed with cellulase, NCC produces significant amount of cello‐oligosaccharides (COS) as reaction intermediates along with glucose and cellobiose. The COS produced by cellulase were categorized into two different moieties based upon their degree of polymerization (DP): low DP (less than 7) COS (LD‐COS) and high DP COS (HD‐COS). Endo‐glucanase (Endo‐G) reacts rapidly on the NCC reducing its DP to 30–60, after which the Endo‐G reaction with NCC ceases. HD‐COS is produced from NCC by the action of Endo‐G, whereas LD‐COS is produced by exo‐glucanase (Exo‐G). β‐Glucosidase (β‐G) hydrolyzes LD‐COS to produce cellobiose, but it does not hydrolyze HD‐COS. DP of NCC affects the action of Exo‐G in such a way that the overall yield is high for high DP NCC. This is in line with previous findings that substrate‐recognition by Exo‐G requires binding on β‐glucan chain with DP of 10 for the hydrolysis to take place. The individual cellulose chain residues within solid having DP less than 10 therefore remain unreacted. The percentage of the unreacted portion would be lower for high DP NCC, which results high overall conversion. The surface area and the number of reactive sites on the substrate facilitate adsorption of enzyme therefore the initial rate of the hydrolysis. The overall extent of conversion of cellulose, however, is controlled primarily by its inherent characteristics such as DP and crystallinity. Biotechnol. Bioeng. 2009;102: 1570–1581. © 2008 Wiley Periodicals, Inc.
Small molecule clearance in ultrafiltration/diafiltration in relation to protein interactions: Study of citrate binding to a Fab
Authors: Harinarayan C. , Skidmore K. , Kao Y. , Zydney A.L. , van Reis R.
Published: November 2008

Ultrafiltration/diafiltration (UFDF) is commonly utilized in the purification of recombinant proteins to concentrate and buffer exchange the product. It is often the final step in the purification process, placing the protein in its final formulation and clearing small molecules introduced in upstream purification steps. This article presents a case study of reduced small molecule clearance in ultrafiltration/diafiltration of an antigen‐binding fragment of a monoclonal antibody. Citrate, a commonly utilized small molecule in downstream processes, is shown to have reduced clearance due to specific interactions with the protein product. The study presents process solutions and utilizes a simple model to characterize clearance of small molecules which exhibit interactions with product protein. Biotechnol. Bioeng. 2009;102: 1718–1722. © 2008 Wiley Periodicals, Inc.
Metabolic control analysis of an enzymatic biofuel cell
Authors: Glykys Doris J. , Banta Scott
Published: November 2008

Metabolic control analysis (MCA) is an analytical technique that aims to quantify the distribution of control that enzymes exhibit over the steady‐state fluxes through a metabolic network. In an enzymatic biofuel cell, the flux of interest is the electrical current generated by the system. Regardless of transport limitations and other constraints, kinetic limitations can become potential bottlenecks in the operation of a biofuel cell. We have used an indirect approach to MCA to investigate a common osmium‐mediated glucose oxidase/laccase enzymatic biofuel cell. The results of the analysis show that the control of the electron flux strongly depends on the total mediator concentrations and the extent of polarization of the individual electrodes. The effect of varying oxygen concentrations is also examined, as oxygen is required for the cathode, but it participates in a non‐productive reaction at the anode. Under normal operating conditions the electrodes will be highly polarized and will both contain high mediator concentrations. This configuration will result in a dominant FCC at the anode, and the conditions that are needed for balanced flux control between the anode and cathode are explored. As increasingly complex bioelectrocatalytic systems and architectures are envisioned, MCA will be a valuable framework to facilitate their design and subsequent operation. Biotechnol. Bioeng. 2009;102: 1624–1635. © 2008 Wiley Periodicals, Inc.
Identification of the limitations on recombinant gene expression in CHO cell lines with varying luciferase production rates
Authors: Mead Emma J. , Chiverton Lesley M. , Smales C. Mark , von der Haar Tobias
Published: November 2008

Mammalian cell lines are currently employed as one of the main cellular factories for the expression of recombinant protein‐based drugs. The establishment of high‐producing cell lines typically begins with a heterogeneous starter population of cells, from which the highest producing cells are selected via empirical approaches. This approach is time consuming, and is likely to encounter natural upper limits imposed by the inherent biology of the cell lines in question. In an attempt to understand both the nature of the variability in populations of cells transfected with recombinant protein encoding DNA and the natural mechanisms of productivity limitation, we developed protocols for the detailed investigation of gene expression pathways in such cell lines. This novel approach was then applied to a set of clonal CHOK1 cell lines producing recombinant luciferase with varying productivities. Our results show that the initial limitation in these cell lines is at the transcriptional level, however in the highest producing cell line post‐translational mechanisms affecting both protein turnover and protein folding become severely limiting. The implications for the development of strategies to engineer cells for enhanced recombinant protein production levels are discussed. Biotechnol. Bioeng. 2009;102: 1593–1602. © 2008 Wiley Periodicals, Inc.
Co‐Metal‐Free Enantioselective Conjugate Addition Reactions of Zinc Reagents
Authors: Ay Sefer , Nieger Martin , Bräse Stefan
Published: November 2008

Asymmetric conjugate addition of diethylzinc to cinnamaldehyde in a co‐metal‐free fashion by using N,O‐ligands with planar and central chirality is described. Different modulations of the ligand structure, including several combinations of the chiral units, indicate that a [2.2]paracyclophane backbone is essential for the activity and the enantioselectivity of the generated active catalyst. By using the optimized ligand, an isolated yield of 90 % was obtained with up to 99 % ee.
Potential of different techniques of preferential crystallization for enantioseparation of racemic compound forming systems
Authors: Polenske Daniel , Lorenz Heike , Seidel‐Morgenstern Andreas
Published: November 2008

Recently the feasibility of preferential crystallization for enantioseparation of racemic compound forming systems has been demonstrated (Lorenz et al., Application of preferential crystallization to resolve racemic compounds in a hybrid process. Chirality 2006;18:828–840; Polenske et al., Separation of the propranolol hydrochloride enantiomers by preferential crystallization: thermodynamic basis and experimental verification. Cryst Growth Des 2007;7:1628–1634). Here, the development and the potential of an efficient separation process operated via two different techniques of preferential crystallization are studied: (1) seeded isothermal preferential crystallization and (2) auto‐seeded polythermal preferential crystallization. Both techniques were investigated in the batch and in the cyclic operation mode. On the example of mandelic acid as a typical racemic compound forming system, it is demonstrated that a cyclic auto‐seeded polythermal process is feasible and significantly more efficient than the seeded isothermal one. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Resonante Sensoren für die In‐situ‐Gasanalytik bei hohen Temperaturen
Authors: Richter D. , Fritze H.
Published: November 2008

Ein auf piezoelektrischen Resonatoren beruhendes Sensorprinzip ermöglicht die simultane Bestimmung der elektrischen und mechanischen Eigenschaften von Sensorschichten in einem Temperaturbereich von 500 bis 900 °C. Mit Hilfe verschiedener Elektroden‐ und Sensorschichtlayouts wird eine hohe Gasselektivität erreicht. Als Resonatormaterial kommt Langasit (La3Ga5SiO14) zum Einsatz, der bis zu seinem Schmelzpunkt von 1470 °C zu Volumenschwingungen angeregt werden kann. Die Leistungsfähigkeit der Sensoren wird anhand der Unterscheidung von Wasserstoff und Kohlenmonoxid bei 600 °C gezeigt. Für CeO2‐beschichtete Resonatoren ergeben sich charakteristische Abhängigkeiten des Messsignals von der Konzentration der Gasspezies. Bei simultaner Verwendung von TiO2‐ und CeO2‐beschichteten Resonatoren lässt sich in H2‐haltiger Atmosphäre eine Nachweisempfindlichkeit für CO von 2 % abschätzen.
Structural variation theorems extended to integrated force method for the analysis of skeletal structures
Authors: Kaveh A. , Najimi M.
Published: November 2008

In this paper, a general formulation of the theorems of structural variation and integrated force method is briefly presented. Application of the structural variation theorems is extended to form a procedure for modified (varied) structures. In the present method, the governing equations of the integrated force method of the main structure are used as structural variation theorem tools to compute forces and displacements of the modified pin‐jointed trusses and rigidly jointed frames. The computational time of the integrated force method, dual integrated force method and the present method is also compared to show the abilities of the present approach. Examples are presented to illustrate the procedure of the present approach compared with the new analysis of a modified structure. Copyright © 2008 John Wiley & Sons, Ltd.
ICI reduction scheme for OFDM system with phase noise over time‐varying channels
Authors: Qin Wen , Peng Qicong
Published: November 2008

For mobile orthogonal frequency division multiplexing (OFDM) systems, time‐varying channels and random phase noise introduced by the oscillator result in severe intercarrier interference (ICI), respectively, and degrade the overall OFDM system performance. However, the existing ICI reduction methods only aim at a single interference source, i.e. either time‐varying channels or phase noise. Therefore, these methods are not suitable for the actual situation. In this paper, we analyze the spectral property of the transfer function composed of time‐varying channels and phase noise, and propose that the transfer function can be approximated by a finite parameter complex exponential basis expansion model (CE‐BEM). Then, a pilot‐aided minimum mean square error estimation is adopted to estimate the CE‐BEM coefficients in order to reconstruct the transfer function and reduce ICI. Finally, our simulation results show how the proposed scheme would improve the system performance in a time‐varying environment with phase noise. Copyright © 2008 John Wiley & Sons, Ltd.
Thromboembolism Prophylaxis in End‐Stage Renal Disease
Authors: Hergenroeder Georgene W. , Levine Robert L. , Miller Charles C.
Published: November 2008

OBJECTIVE

This study aimed to identify risk for venous thromboembolism (VTE) and prophylaxis patterns for end‐stage renal disease (ESRD) patients admitted through the emergency department (ED).

METHODS

ESRD patients admitted through the ED in an urban teaching hospital were enrolled in this observational cohort. Admissions through the ED were reviewed as part of a VTE prophylaxis utilization analysis. Patients with moderate to high risk for VTE based on a modified risk assessment model were considered in need of prophylaxis. Prophylaxis was defined as medical (heparin/low‐molecular‐weight heparin) or mechanical prophylaxis. Readmissions during the following year were monitored through an electronic database for thrombosis‐related International Classification of Diseases, Ninth Revision codes.

RESULTS

Thirty patients met enrollment criteria. Twenty of the 30 patients (67%) were at moderate or higher risk for VTE and considered in need of VTE prophylaxis; 6 patients (30%) were actively prophylaxed. High risk was associated with a lower probability of appropriate prophylaxis (p < 0.04). Three patients (10%) had a clotting‐related outcome.

CONCLUSIONS

The 30% rate of VTE prophylaxis in the ESRD group is consistent with the general prophylaxis rate. Lower‐risk patients appropriately received no treatment, whereas treatment was omitted in high‐risk ESRD patients. The observed rate of 10% thrombosis‐related diagnoses may underestimate the actual thrombosis rate.
Shrubs enhance resilience of a semi‐arid ecosystem by engineering and regrowth
Authors: Segoli Moran , Ungar Eugene David , Shachak Moshe
Published: November 2008

Semi‐arid ecosystems in the Mediterranean basin show a high degree of resilience, despite thousands of years of human disturbance. It has been suggested that this resilience is facilitated by a landscape structure that consists of woody vegetation and intershrub patches of crusted soil. We hypothesized that the woody vegetation patches have two main properties that increase the resilience of the ecosystem. The first property is the capability to accumulate water, and we hypothesized that this continues to function after anthropogenic disturbances to the shrubs. This was field‐tested with a rainfall simulator by comparing the amounts of runoff and soil erosion generated by crusted intershrub patches, intact shrub patches, and disturbed shrub patches. The second property is the ability of the woody vegetation to recover after disturbances. This was tested by measuring the recovery rate of the woody vegetation, during 2 consecutive years after canopy removal. Intact and disturbed shrub patches generated similar amounts of runoff and soil erosion to one another, and much lower than crusted intershrub patches, and both kinds of shrub patches had deeper water infiltration. These results suggest that the accumulation of water under the shrub is due to surface and sub‐surface soil properties, and not canopy properties. After anthropogenic removal of the woody vegetation canopy, most of the individuals regrew. These combined results suggest that the ecosystem can remain resilient to certain anthropogenic disturbances by virtue of ecosystem engineering and fast recovery by woody vegetation patches that act to conserve resources and to impede their leakage from the ecosystem. Copyright © 2008 John Wiley & Sons, Ltd.
Quasi‐static and pseudo‐dynamic testing of unbonded post‐tensioned rocking bridge piers with external replaceable dissipaters
Authors: Marriott Dion , Pampanin Stefano , Palermo Alessandro
Published: November 2008

It has been well documented that following a major earthquake a substantial percentage of economic loss results from downtime of essential lifelines in and out of major urban centres. This has thus led to an improvement of both performance‐based seismic design philosophies and to the development of cost‐effective seismic structural systems capable of guaranteeing a high level of protection, low structural damage and reduced downtime after a design‐level seismic event. An example of such technology is the development of unbonded post‐tensioned techniques in combination with rocking–dissipating connections.

In this contribution, further advances in the development of high‐performance seismic‐resistant bridge piers are achieved through the experimental validation of unbonded post‐tensioned bridge piers with external, fully replaceable, mild steel hysteretic dissipaters.

The experimental response of three 1 : 3 scale unbonded, post‐tensioned cantilever bridge piers, subjected to quasi‐static and pseudo‐dynamic loading protocols, are presented and compared with an equivalently reinforced monolithic benchmark. Minimal physical damage is observed for the post‐tensioned systems, which exhibit very stable energy dissipation and re‐centring properties. Furthermore, the external dissipaters can be easily replaced if severely damaged under a major (higher than expected) earthquake event. Thus, negligible residual deformations, limited repair costs and downtime can be achieved for critical lifeline components. Satisfactory analytical–experimental comparisons are also presented as a further confirmation of the reliability of the design procedure and of the modelling techniques. Copyright © 2008 John Wiley & Sons, Ltd.
In‐plane strength of unreinforced masonry piers
Authors: Calderini Chiara , Cattari Serena , Lagomarsino Sergio
Published: November 2008

The definition of adequate simplified models to assess the in‐plane load‐bearing capacity of masonry piers, in terms of both strength and displacement, plays a fundamental role in the seismic verification of masonry buildings. In this paper, a critical review of the most widespread strength criteria present in the literature and codes to interpret the failure modes of piers (rocking, crushing, bed joint sliding or diagonal cracking) are proposed. Models are usually based on an approximate evaluation of the stress state produced by the external forces in a few points/sections and on its assessment with reference to a limit strength domain. The aim of the review is to assess their reliability by discussing the hypotheses, which they are based on (assumed stress states; choice of reference points/sections on which to assess the pier strength; characteristics of the limit strength domain) and to verify the conditions for their proper use in practice, in terms of both stress fields (depending on the geometry of the pier, boundary conditions and applied loads) and types of masonry (i.e. regular brick masonry vs rubble stone masonry). In order to achieve these objectives, parametric nonlinear finite element analyses are performed and different experimental data available in the literature are analysed and compared. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of the mycotoxin fumonisin B1 on cell death in human kidney cells and human lung fibroblasts in primary culture
Authors: Schwerdt G. , Königs M. , Holzinger H. , Humpf H. U. , Gekle M.
Published: November 2008

Fumonisins are mycotoxins produced by Fusarium verticillioides. The toxic effects of fumonisin B1 (FB1) at the cellular level consist of a mixture of both necrosis and apoptosis. We studied the effect of FB1 in human lung fibroblasts (NHLF) and human kidney epithelial cells (RPTEC) in primary culture. Apoptotic and necrotic cell death, collagen and fibronectin secretion were determined mainly after 14 days' exposure. The protein content of NHLF and RPTEC cells was slightly increased after 14 days' exposure to low FB1 concentrations (0.1 or 1 µm). Caspase‐3 activity tended to increase in NHLF and to decrease in RPTEC cells with higher FB1 concentrations after 14 days' exposure. LDH release was slightly decreased in both cell types after 14 days. Collagen I and III secretion was enhanced in NHLF cells. Collagen III was decreased in RPTEC. Collagen IV was not changed in both cell types. Fibronectin secretion was uninfluenced in RPTEC and interim increased in NHLF. Furthermore LC‐MS/MS studies did not give any hints for a metabolism of FB1. Therefore, the main risk of prolonged FB1 exposure seems to be altered collagen secretion pattern. Copyright © 2008 John Wiley & Sons, Ltd.
Using regional wind fields to improve general circulation model forecasts of July–September Sahel rainfall
Authors: Ndiaye Ousmane , Goddard Lisa , Ward M. Neil
Published: November 2008

This study develops and applies a model output statistics (MOS) approach for correcting poor general circulation model (GCM) seasonal rainfall predictions over the Sahel region of West Africa. It illustrates a methodology for approaching the MOS prediction of regional rainfall, drawing on knowledge of the regional circulation system.

The ECHAM4.5 GCM has very little skill in predicting July–September Sahel rainfall. However, the GCM is much more capable of reproducing the regional wind circulation at 925 hPa, especially over the tropical Atlantic. This is capitalized upon using a MOS approach that applies empirical orthogonal functions (EOFs) of the model's regional (tropical Atlantic and West Africa) 925 hPa wind as predictors in a regression with observed Sahel rainfall as the predictand. Over 1968–2002, the MOS system requires only the first wind EOF and improves the correlation skill of July–September Sahel rainfall from 0.07 (raw GCM) to 0.57. The MOS system is applied to GCM experiments using persisted sea‐surface temperature (SST) anomalies from the months of June, May and April respectively, to estimate the potential of the system to make forecasts with lead times between 0 and 2 months ahead of the July–September season. Almost identical skill is achieved from the June SST, but May and April SSTs show a substantial decline in skill. This is mainly associated with a tendency in tropical Pacific SST anomalies from May to June, highlighting development of El Niño (La Niña) in Sahel dry (wet) years, though statistically significant tendencies are also found in the tropical Atlantic and Indian Oceans. The MOS approach is robust in simulation experiments over the 1950–2002 period, when one additional EOF in the MOS system is found to best capture the tropical Atlantic influence. For increasing forecast lead time, targeted prediction of SST from April to June is motivated by these findings. Copyright © 2008 Royal Meteorological Society