bluuebunny/crossref_metadata_2025 huggingface dataset:
Photophysical properties and morphology of fluorene‐alt‐benzene based conjugated polymers
Authors: Yang Gui‐Zhong , Chen Peng , Liu Tianxi , Wang Min , Huang Wei
Published: August 2006

A series of fluorene‐alt‐benzene based conjugated main chain polymers attached chemically with different lengths of alkyl side chains on phenylene rings were designed and synthesized by a palladium catalyzed Suzuki coupling reaction. The UV‐vis absorption and fluorescence spectra, thermal stability of spectral property, phase transition behavior and morphology of the synthesized polymers were investigated. With increasing the length of the alkyl side chain, the UV and fluorescence spectra exhibit obvious blue shift compared with those of the unsubstituted polymer. The alkyl substitution improves the thermal stability of the spectra due to the steric hindrance of the alkyl side chains and thus the effective separation of the main chain backbones. The phase transition behavior is closely related to the length of alkyl side chains attached on the phenylene rings. The annealed polymer films display characteristic nematic liquid crystalline texture. Transmission electron microscopy (TEM) observations indicate that solvent‐cast thin deposits of all the polymers show typical fibrillar morphology. Copyright © 2006 John Wiley & Sons, Ltd.
Highly soluble diphenylfluorene‐based cardo copolyimides containing perylene units
Authors: Xu Shengang , Jin Yuxia , Yang Mujie , Bai Fenglian , Cao Shaokui
Published: August 2006

Two series of novel ternary copolyimides containing perylene and fluorene units in the backbone were synthesized by one‐step polycondensation of diamine (4,4′‐(9H‐fluoren‐9‐ylidene)bisphenylamine, FBPA) with perylene dianhydride (3,4,9,10‐perylenetetracarboxylic dianhydride, PTCDA) and a comonomer [4,4′‐(hexafluoroisopropylidene) diphthalic anhydride, 6FDA or 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride, BDTA]. The polymers were named as PFFx (PTCDA‐FBPA‐6FDA) and PFBx (PTCDA‐FBPA‐BTDA), respectively, and their chemical structures were identified by FT‐IR spectra and elemental analyses. Perylene contents in the copolyimides were determined through a quantitative UV‐vis spectroscopy method, which are in agreement with the values calculated from the added raw materials both for PFFx and PFBx. Gel permeation chromatography (GPC) measurement suggested that the weight average molecular weight (Mw) is in the range 2.1–5.09 × 104 and the molecular weight distribution (MWD) is 1.86–2.72 for PFFx, and those for PFBx are 2.64–4.73 × 104 and 2.44–2.92, respectively. Thermogravimetric analysis (TGA) measurements showed that the copolyimides are very thermally stable with a temperature of 10% weight loss (T10) in the range 546–563°C for PFFx, and 538–548°C for PFBx. The copolyimides also have good solubility in common organic solvents such as chloroform and tetrahydrofuran. These unique properties can be attributed to the existence of the bulky diphenylfluorene moieties in the polymer backbone. All the copolyimides can emit strong fluorescence both in solution and in films, which make them possibly be used as thermostable light‐emitting materials for organic light‐emitting diodes. Copyright © 2006 John Wiley & Sons, Ltd.
Rituximab for treatment of opsoclonus‐myoclonus syndrome in neuroblastoma
Authors: Burke Michael J. , Cohn Susan L.
Published: August 2006

Opsoclonus‐myoclonus syndrome (OMS) is a rare paraneoplastic syndrome that occurs in 2%–3% of patients with neuroblastoma. The cause of this syndrome is believed to be immune mediated, but the exact mechanism still remains unclear. There is an urgent need to improve our current strategies for treating patients with OMS, as many patients have significant long‐term neurologic deficits and behavior disorders with current treatment approaches. Therapies that have shown to improve symptoms in these patients have ranged from ACTH and corticosteroids, to intravenous gammaglobulin and plasmapheresis. We report our experience with Rituximab in a patient with neuroblastoma and OMS. Pediatr Blood Cancer 2008;50:679–680. © 2006 Wiley‐Liss, Inc.
A phase 2 trial of all‐trans‐retinoic acid in combination with interferon‐α2a in children with recurrent neuroblastoma or Wilms tumor: A Pediatric Oncology Branch, NCI and Children's Oncology Group Study
Authors: Adamson Peter C. , Matthay Katherine K. , O'Brien Michelle , Reaman Gregory H. , Sato Judith K. , Balis Frank M.
Published: August 2006

Background

The combination of the antiproliferative and differentiation‐inducing effects of retinoids together with the antiproliferative, immunostimulatory, and differentiation‐potentiating effects of interferon‐α (IFN‐α) were the basis for the development of this combination in pediatric patients with refractory neuroblastoma or Wilms tumor.

Procedure

A phase 2 trial of all‐trans‐retinoic acid (ATRA), administered orally at a dose of 90 mg/m2/day in three divided doses for 3 consecutive days per week, and IFN‐α2a, administered subcutaneously daily at a dose of 3 × 106 U/m2/day for 5 consecutive days per week, in 4 week cycles was performed. A two‐stage design was used for each disease stratum.

Results

Seventeen patients (16 evaluable) with neuroblastoma, median age 9 years, and 15 patients (14 evaluable) with Wilms tumor, median age 6 years, were enrolled. Overall, the combination was well tolerated, with headache being the most common toxicity observed. There were no complete or partial responses. The median number of cycles administered was 1 (range 1–9). Four patients with neuroblastoma had stable disease for 12 or more weeks.

Conclusions

The combination of ATRA and IFN‐α2a was inactive in children with relapsed or refractory neuroblastoma and Wilms tumor. The lack of activity with this combination in children with refractory neuroblastoma is similar to the disappointing phase 2 results of single agent 13‐cis‐retinoic‐acid (13cRA) and does not support further development of ATRA for children with relapsed neuroblastoma. Pediatr Blood Cancer 2007;49:661–665. © 2006 Wiley‐Liss, Inc.
The new Swedish Prescribed Drug Register—Opportunities for pharmacoepidemiological research and experience from the first six months
Authors: Wettermark Björn , Hammar Niklas , MichaelFored C. , Leimanis Andrejs , Otterblad Olausson Petra , Bergman Ulf , Persson Ingemar , Sundström Anders , Westerholm Barbro , Rosén Måns
Published: August 2006

Purpose

To describe the content and potentials of the new Swedish national register on prescribed and dispensed medicines.

Methods

The Swedish Prescribed Drug Register contains information about age, sex and unique identifier of the patient as well as the prescriber's profession and practice. Information regarding drug utilization and expenditures for prescribed drugs in the entire Swedish population was extracted from the first six months July–December 2005 and compared with total drug sales in the country including OTC and hospital use.

Results

The total quantity of drugs sold in Sweden was 2666 million DDDs, corresponding to 1608 DDD/1000 inhabitants daily. The total expenditures were 1.6 billion Euro. The prescribed drugs, included in the register, accounted for 84% of the total utilization and 77% of the total expenditures. About half of all men and two‐thirds of all women in the country purchased drugs. The proportion increased by age. The most common drugs for chronic treatment were diuretics among women (8.8% of the population) and antithrombotic agents among men (7.6%). Psychotropic drugs, corticosteroids and analgesics were more common among women, while men used antithrombotic agents, antidiabetic drugs, lipid lowering agents and ACE inhibitors to a greater extent.

Conclusions

The new register provides valuable data on exposure to drugs and is useful to study patterns of drug utilization. The possibilities for record linkage to other health registers gives from an international perspective good opportunities to explore drug and disease associations and the risks, benefits, effectiveness and health economical effects of drug use. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative assessment of the gastrointestinal and cardiovascular risk‐benefit of celecoxib compared to individual NSAIDs at the population level
Authors: Varas‐Lorenzo Cristina , Maguire Andrew , Castellsague Jordi , Perez‐Gutthann Susana
Published: August 2006

Purpose

To estimate the net cardiovascular (CV) (coronary heart disease, stroke, congestive heart failure), and gastrointestinal (GI) (peptic ulcer complications) risk‐benefit public health impact of the use of celecoxib compared to non‐selective NSAIDs in the arthritis population.

Methods

We applied discrete event simulation models to data from the US National Health Surveys, CV risk‐prediction models from the Framingham Heart Study, and population‐based studies. Models took into account the multifactorial effect of risk factors, comorbidity, and competing risk of mortality. We simulated the natural history of CV and GI disease in the U.S. arthritis population over 1 year, through the individual baseline cardiovascular and gastrointestinal risk profile. This model was modified with relative risks associated with the use of each treatment. The mean number of events was estimated for each end‐point in each model: natural history, celecoxib, diclofenac, ibuprofen, naproxen. The number of events for celecoxib was compared with each NSAID.

Results

The evaluation included 1% of the U.S. population with arthritis. Celecoxib, when applied to 100 000 patients over 1 year, resulted in 570 (range from sensitivity analysis: 440–691), 226 (124–313), and 746 (612–868) fewer ulcer complications than diclofenac, ibuprofen, and naproxen, respectively. There were 20 (16–25), 8 (4–12), and 27 (22–32) fewer deaths from ulcer complications, respectively. No increase in cardiovascular events or all cause mortality was observed for celecoxib versus the other individual NSAIDs.

Conclusion

Results from these simulations suggest a gastrointestinal benefit for celecoxib not offset by increased cardiovascular events or mortality. The methodology used here provides a risk‐benefit assessment framework for evaluating the public heath impact of drugs. Copyright © 2006 John Wiley & Sons, Ltd.
Ring‐opening metathesis polymerization of amino acid‐functionalized norbornene derivatives
Authors: Sutthasupa Sutthira , Terada Kayo , Sanda Fumio , Masuda Toshio
Published: August 2006

Amino acid‐derived novel norbornene derivatives, N,N′‐(endo‐bicyclo[2.2.1] hept‐5‐en‐2,3‐diyldicarbonyl) bis‐L‐alanine methyl ester (NBA), N,N′‐(endo‐bicyclo[2.2.1]hept‐5‐en‐2,3‐diyldicarbonyl) bis‐L‐leucine methyl ester (NBL), N,N′‐(endo‐bicyclo[2.2.1]hept‐5‐en‐2,3‐diyldicarbonyl) bis‐L‐phenylalanine methyl ester (NBF) were synthesized and polymerized using the Grubbs 2nd generation ruthenium (Ru) catalyst. Although NBA, NBL, and NBF did not undergo homopolymerization, they underwent copolymerization with norbornene (NB) to give the copolymers with Mn ranging from 5200 to 38,100. The maximum incorporation ratio of the amino acid‐based unit was 9%, and the cis contents of the main chain were 54–66%. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5337–5343, 2006
Para‐linked and meta‐linked cationic water‐soluble fluorene‐containing poly(aryleneethynylene)s: Conformational changes and their effects on iron–sulfur protein detection
Authors: Huang Yan‐Qin , Fan Qu‐Li , Li Sheng‐Biao , Lu Xiao‐Mei , Cheng Fan , Zhang Guang‐Wei , Chen Yi , Wang Lian‐Hui , Huang Wei
Published: August 2006

Four para‐linked or meta‐linked cationic water‐soluble fluorene‐containing poly(aryleneethynylene)s (PAEs) were synthesized to investigate the solvent‐induced π‐stacked self‐assembly. These PAE backbones are composed of fluorenylene and phenylene units, which are alternatively linked by ethynylene bonds. UV–vis absorption and photoluminescence spectra were used to study their conformational changes as solvent was gradually changed from MeOH to H2O. In pure water, with gradually increased meta‐phenylene content (0, 50, and 100%), they underwent a gradual transition process of conformation from disordered aggregate structure to helix structure, which was not compactly folded. Moreover, the polymer with an ammonium‐functionalized side chain on the meta‐phenylene unit appeared to adopt a more incompact or extended helix conformation than the corresponding one without this side chain. Furthermore, the conformational changes of these cationic PAEs in H2O were used to study their effects on biological detection. Rubredoxin (Rd), a type of anionic iron–sulfur‐based electron transfer protein, was chosen to act as biological analyte in the fluorescence quenching experiments of these polymers. Preliminary results suggest that they all exhibit amplified fluorescence quenching, and that the polymer with more features of helix conformation tends to be quenched by Rd more efficiently. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5424–5437, 2006
Synthesis and properties of low‐dielectric‐constant polyimides with introduced reactive fluorine polyhedral oligomeric silsesquioxanes
Authors: Ye Yun‐Sheng , Chen Wen‐Yi , Wang Yen‐Zen
Published: August 2006

A high‐performance, low‐dielectric‐constant polyimide (PI) nanocomposite from poly(amic acid) (PAA) cured with a reactive fluorine polyhedral oligomeric silsesquioxane (POSS) isomer was successfully synthesized. The features of this reactive fluorine POSS isomer [octakis(dimethylsiloxyhexafluoropropylglycidyl ether)silsesquioxane (OFG)] provided two important approaches (containing fluorine or being porous in the polymer matrix) of reducing the dielectric constant of PI. This reactive POSS isomer had an average of four epoxy groups and four fluorine groups on the POSS cage, and the epoxy groups could be cured with PAA to form a network framework of a PI/POSS nanocomposite. The PI/OFG nanocomposite had a high crosslinking density, high porosity (24.3%), high hydrophobicity, and low polarizability. These properties enhanced the thermal (glass‐transition temperature ∼ 362 °C) and dielectric (dielectric constant ∼2.30) properties of PI more than other POSS derivatives introduced into the PI backbone. A large number of small POSS particles (<10 nm) were embedded inside the PI matrix when the OFG content was low, whereas interconnected POSS aggregation domains were observed when the OFG content was high. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5391–5402, 2006
Evaluation of the Mechanical Resistance of a Powder‐powder Coating by Modulated Dry Feed Particle Size Analysis
Authors: Vilela Ana , Concepcion Lucia , Accart Philippe , Chamayou Alain , Baron Michel , Dodds John A.
Published: August 2006

Dry powder coating is a powerful method for modifying the surface properties of particles whilst retaining their essential bulk properties. The coating of a host powder by guest particles can be achieved via different means ranging from simple stirring together of the two components, to high energy impact coating in devices such as a Nara Hybridizer or Turbula Mixer. The quality of the powder coating resulting from such methods is an important parameter, which depends both on the force of the mechanical action used, and also the physico‐chemical interactions between the host and guest particles. Here, a method for evaluating the strength of host‐guest interactions based on particle size analysis using a standard Malvern Mastersizer with dry powder feed is presented. Basically, the liberation of small guest particles from host particles can be achieved by increasing the air pressure, and the presence of liberated fine particles mixed with guest particles can be detected from differences in volume and number distributions. Complementary examination is undertaken using an environmental scanning electron microscope (ESEM). This technique has been used to evaluate the interaction strength of a coating of hydrophobic magnesium stearate on a herbal extract (Harpagophytum). It is shown that effective coating can be achieved by three different means: simple stirring, a Turbula Mixer and by using a Nara Hybridizer. The respective strength of the coatings is greater with increasing mechanical force used for the process. The method is proposed as a simple means of evaluating powder‐powder coating processes.
In‐line Comparison of Particle Sizing by Static Light Scattering, Time‐of‐Transition, and Dynamic Image Analysis
Authors: Saveyn Hans , Thu Tran Le , Govoreanu Ruxandra , Van der Meeren Paul , Vanrolleghem Peter A.
Published: August 2006

Particle size analysis is important in both process and quality control. Different techniques are currently available. In this contribution, the characteristics of three techniques, based on Static Light Scattering (SLS), Time‐of‐Transition (TOT), and Dynamic Image Analysis (DIA), are compared using various aqueous dispersions. Hereby, the techniques were connected in series, so that simultaneous measurements could be performed on the same sample. The experimental results demonstrated that each of the investigated techniques has its strengths and limitations. Thus, SLS results may be largely affected by the choice of the refractive index of the dispersed particles as well as by the choice of the inversion algorithm to convert the angular spectrum to a particle size distribution. As neither TOT or DIA require information concerning the (complex) refractive index of the particles and are based on the detection of individual particles, these techniques are claimed to be very useful for measuring particles in the micrometer size range, although the measurement can be heavily affected by the particle transparency and concentration. Furthermore, all the techniques appear more suited to discerning small particles within a population of large particles than to detecting large particles within a population of small particles. Finally, TOT is much less sensitive towards submicron particles, as compared to SLS. The latter technique does not only have a broader dynamic range, which extends down to the submicron range, but also produces reliable results at higher sample concentrations as compared to TOT and DIA.
Protein and Nanoparticle Characterisation Using Light Scattering Techniques
Authors: Kaszuba Michael , Connah Malcolm T.
Published: August 2006

The technique of dynamic light scattering is well suited to the measurement of the size of colloidal dispersions. Traditionally, measurements of large particle sizes or particles that are highly scattering would require high dilution of the sample in order to avoid multiple scattering effects. Conversely, measurement of very small and/or poorly scattering particles or samples that are very dilute are difficult unless high‐powered lasers are used. These problems have been addressed in a light scattering instrument incorporating novel non‐invasive backscatter optics (NIBS). This novel optic arrangement maximises the detection of scattered light while maintaining signal quality. In addition to the increased size and concentration range for DLS applications, the increased sensitivity obtained from this optical arrangement also allows for the determination of absolute molecular weight using static light scattering measurements. Accurate molecular weight measurements can be achieved at a single scattering angle for molecules that do not show any angular dependence in their scattering intensity. This paper describes the advantages of using backscatter optics and illustrates the capabilities of the technology by reporting results of measurements from various applications.
Size and Structure Characterization of Dye Flocs during Coagulation of Reactive Black 5 Dye
Authors: Janeczko Marta , Gaydardzhiev Stoyan
Published: August 2006

This paper deals with results from laboratory scale experiments with model dye effluents comprising of the commercially used textile diazo dye, CI “Reactive Black 5”, coagulated with ZETAG type primary coagulants. Size and structure analysis of flocs in coagulated dye sludge was undertaken in order to evaluate their separation abilities. The particle size distribution was estimated by use of a Galai CIS‐100 particle counting system working on a time‐of‐transition principle, while their fractal dimension was obtained from laser scattering instrument in LALS mode. An image analysis of the flocculated dye‐sludge has also been carried out. In parallel to the flocs characterization, the measurement of surface charge density of coagulated dye sludge was performed with the aim of linking surface charge data with the floc characteristics, and on this basis, to outline the predominant mechanism of color removal. It was found that flocs produced at optimal dosage are characterized by large sizes and a high value of fractal dimension, which is manifested in a very good level of color removal by sedimentation. The evident correlation between the surface charge density progression of coagulated dye flocs and color removal, suggests adsorption and charge neutralization as the predominant mechanism of dye destabilization.
Single Particle Detection and Size Analysis with Statistical Methods from Particle Imaging Data
Authors: Wessely Benno , Gabsch Stephan , Altmann Justus , Babick Frank
Published: August 2006

The application of imaging techniques for particle characterization in the micrometer range is often advantageous under process conditions. Particle imaging analysis of disperse systems not only allows the evaluation of the particle size, but also the concentration of particles and particle shape. Under process conditions online imaging techniques have to deal with high particle concentrations and sometimes with high velocities. Two general principles for the evaluation of particle images are discussed in this paper: particle analysis by means of object identification and a statistical method to analyze overlapping clusters of particles.
Raman spectroelectrochemistry of index‐identified metallic carbon nanotubes: The resonance rule revisited
Authors: Kavan Ladislav , Kalbáč Martin , Zukalová Markéta , Dunsch Lothar
Published: August 2006

Raman spectroelectrochemistry of HiPco single‐walled carbon nanotubes was studied at conditions, when the radial breathing modes can be assigned to defined tubes or to families of tubes. The particular tubes exhibit a varying sensitivity to electrochemical doping, monitored as an attenuation of the RBM intensities. Tubes in optimum resonance with the exciting laser show the strongest doping‐induced drop of the RBM intensity while those out of resonance have only a week response to doping. Our “resonance rule” is particularly important for metallic tubes, which cannot be indexed similarly to semiconducting tubes using photoluminescence data. This paper is focused on metallic tubes, which are resonance enhanced through the E 11M optical transition. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The N@C60 nuclear spin qubit: Bang‐bang decoupling and ultrafast phase gates
Authors: Morton John J. L. , Tyryshkin Alexei M. , Ardavan Arzhang , Benjamin Simon C. , Porfyrakis Kyriakos , Lyon S. A. , Briggs G. Andrew D.
Published: August 2006

Nuclear spins have been proposed for the embodiment of quantum information and yielded the most complex demonstrations of quantum algorithms to date. However, the weak thermal polarisation of nuclear spins in experimentally accessible conditions has presented a barrier to further scaling. Here, we discuss the benefits of a coupled electron spin to the nuclear spin qubit and demonstrate the ideas using the 14N nuclear spin in the N@C60 molecule. In addition to providing a resource for nuclear spin polarisation and detection, the electron spin can be exploited to perform ultrafast nuclear spin phase gates, which can in turn be used to dynamically bang‐bang decouple the nuclear spin from unwanted interactions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
‘Information‐Based‐Acquisition’ (IBA) technique with an ion‐trap/time‐of‐flight mass spectrometer for high‐throughput and reliable protein profiling
Authors: Yokosuka Toshiyuki , Yoshinari Kiyomi , Kobayashi Kinya , Ohtake Atsushi , Hirabayashi Atsumu , Hashimoto Yuichiro , Waki Izumi , Takao Toshifumi
Published: August 2006

Highly complex protein mixtures can be analyzed after proteolysis using liquid chromatography/mass spectrometry (LC/MS). In an LC/MS run, intense peptide ions originating from high‐abundance proteins are preferentially analyzed using tandem mass spectrometry (MS2), so obtaining the MS2 spectra of peptide ions from low‐abundance proteins is difficult even if such ions are detected. Furthermore, the MS2 spectra may produce insufficient information to identify the peptides or proteins. To solve these problems, we have developed a real‐time optimization technique for MS2, called the Information‐Based‐Acquisition (IBA) system. In a preliminary LC/MS run, a few of the most intense ions detected in every MS spectrum are selected as precursors for MS2 and their masses, charge states and retention times are automatically registered in an internal database. In the next run, a sample similar to that used in the first run is analyzed using database searching. Then, the ions registered in the database are excluded from the precursor ion selection to avoid duplicate MS2 analyses. Furthermore, real‐time de novo sequencing is performed just after obtaining the MS2 spectrum, and an MS3 spectrum is obtained for accurate peptide identification when the number of interpreted amino acids in the MS2 spectrum is less than five. We applied the IBA system to a yeast cell lysate which is a typical crude sample, using a nanoLC/ion‐trap time‐of flight (IT/TOF) mass spectrometer, repeating the same LC/MS run five times. The obtained MS2 and MS3 spectra were analyzed by applying the Mascot® (Matrix Science, Boston, MA, USA) search engine to identify proteins from the sequence database. The total number of identified proteins in five LC/MS runs was three times higher than that in the first run and the ion scores for peptide identification also significantly increased, by about 70%, when the MS3 spectra were used, combined with the MS2 spectra, before being subjected to Mascot® analysis. Copyright © 2006 John Wiley & Sons, Ltd.
Entropic criteria for protein folding derived from recurrences: Six residues patch as the basic protein word
Authors: Zbilut Joseph P. , Chua Gek Huey , Krishnan Arun , Bossa Cecilia , Colafranceschi Mauro , Giuliani Alessandro
Published: August 2006

Some research has suggested that patches of six constitute an important amino acid window length in proteins for conveying information. We present database evidence that supports this conjecture, as well as additional recurrence‐based data that characterization and quantification of these words affect the folding/aggregation features of proteins. Other indirect evidence is presented and discussed.
Extracellular tau is toxic to neuronal cells
Authors: Gómez-Ramos Alberto , Díaz-Hernández Miguel , Cuadros Raquel , Hernández Félix , Avila Jesús
Published: August 2006

The degeneration of neurons in disorders such as Alzheimer's disease has an immediate consequence, the release of intracellular proteins into the extracellular space. One of these proteins, tau, has proven to be toxic when added to cultured neuronal cells. This toxicity varies according to the degree of protein aggregation. The addition of tau to cultured neuroblastoma cells provoked an increase in the levels of intracellular calcium, which is followed by cell death. We suggest that this phenomenon may be mediated by the interaction of tau with muscarinic receptors, which promotes the liberation of calcium from intracellular stores.
The AtNFXL1 gene encodes a NF‐X1 type zinc finger protein required for growth under salt stress
Authors: Lisso Janina , Altmann Thomas , Müssig Carsten
Published: August 2006

The human NF‐X1 protein and homologous proteins in eukaryotes represent a class of transcription factors which are characterised by NF‐X1 type zinc finger motifs. The Arabidopsis genome encodes two NF‐X1 homologs, which we termed AtNFXL1 and AtNFXL2. Growth and survival was impaired in atnfxl1 knock‐out mutants and AtNFXL1‐antisense plants under salt stress in comparison to wild‐type plants. In contrast, 35S∷AtNFXL1 plants showed higher survival rates. The AtNFXL2 protein potentially plays an antagonistic role. The Arabidopsis NF‐X1 type zinc finger proteins likely are part of regulatory mechanisms, which protect major processes such as photosynthesis.
Histological and biological developmental characterization of the human cerebellar cortex
Authors: Lavezzi Anna Maria , Ottaviani Giulia , Terni Lorella , Matturri Luigi
Published: August 2006

The aim of this study was to investigate the histological and biological features of the human cerebellar cortex development and differentiation. We analyzed 52 brains of fetal and infant death victims, aged from 17 gestational weeks to 12th postnatal month. In particular, in the cerebellar cortex at different ages we evaluated, besides the structural aspects, the expression of several biomarkers implicated in proliferative processes (c‐fos, PCNA and apoptosis). We observed morphological patterns progressively evolving every month, from the indefinite structure of the second gestational trimester to the four‐layered structure (external granular layer, molecular layer, Purkinje cell layer, internal granular layer) of the late fetal cortex and subsequently to the three‐layered postnatal definitive morphology, due to involution of the external granular layer. The evaluation of the biological features of the cerebellar cortex showed high proliferative activity mainly confined to the transient external granular layer in prenatal life, and high apoptotic index after birth. Thus, the histological examination, better with the support of biomarker investigations, allows with accuracy to describe the dynamic sequence of steps that occur in human cerebellar cortex development and to establish in each case the age, namely the pre‐ or postnatal month of life. Consequently, we can diagnose delayed or altered processes of differentiation during the development of the human cerebellar cortex.
Kinetic Measurements of Protein Conformation in a Microchip
Authors: Kerby Matthew B. , Lee Jinkee , Ziperstein Joshua , Tripathi Anubhav
Published: August 2006

This paper presents a microchip‐based system for collecting kinetic time‐based information on protein refolding and unfolding. Dynamic protein conformational change pathways were studied in microchannel flow using a microfluidic device. We present a protein‐conserving approach for quantifying refolding by dynamically varying the concentration of the chemical denaturants, guanidine hydrochloride and urea. Short diffusion distances in the microchannel result in rapid equilibrium between protein and titrating solutions. Dilutions on the chip were tightly regulated using pressure controls rather than syringe‐based flow, as verified with extensive on‐chip tracer dye controls. To validate this protein assay method, folding transition experiments were performed using two well‐characterized proteins, human serum albumin (HSA) and bovine carbonic anhydrase (BCA). Transition events were monitored through fluorescence intensity shifts of the protein dye 8‐anilino‐1‐naphthalenesulfonic acid (ANS) during dilutions of protein from urea or guanidine hydrochloride solutions. The enzymatic activity of refolded BCA was measured by UV absorption through the conversion of p‐nitrophenyl acetate (p‐NPA). The microchip protein refolding transitions using ANS were well‐correlated with conventional plate‐based experiments. The microfluidic platform enables refolding studies to identify rapidly the optimal folding strategy for a protein using small quantities of material.
Satellite‐based assessment of top of atmosphere anthropogenic aerosol radiative forcing over cloud‐free oceans
Authors: Christopher Sundar A. , Zhang Jianglong , Kaufman Yoram J. , Remer Lorraine A.
Published: August 2006

Most assessments of the direct climate forcing (DCF) of anthropogenic aerosols are from numerical simulations. However, recent advances in remote sensing techniques allow the separation of fine mode aerosols (anthropogenic aerosol is mostly fine aerosol) from coarse mode aerosols (largely marine and dust, which are mostly natural) from satellite data such as the Moderate Resolution Imaging SpectroRadiometer (MODIS). Here, by combining MODIS narrowband measurements with broadband radiative flux data sets from the Clouds and the Earth's Radiant Energy System (CERES), we provide a measurement‐based assessment of the global direct climate forcing (DCF) of anthropogenic aerosols at the top of atmosphere (TOA) only for cloud free oceans. The mean TOA DCF of anthropogenic aerosols over cloud‐freeoceans [60N–60S] is −1.4 ± 0.9 Wm−2, which is in excellent agreement (mean value of −1.4 Wm−2) with a recent observational study by Kaufman et al. [2005].
Experimental investigation of the dissolution of quartz by a muscovite mica surface: Implications for pressure solution
Authors: Meyer Emily E. , Greene George W. , Alcantar Norma A. , Israelachvili Jacob N. , Boles James R.
Published: August 2006

Using the surface forces apparatus, which can measure small changes in thickness occurring even at essentially geological timescales, we have measured dissolution of quartz sheets when pressed against muscovite mica surfaces in aqueous electrolyte solution, but no dissolution is observed under dry conditions. It is postulated that the dissolved quartz may reprecipitate outside the contact junction as a fragile silica gel, which could be the main factor limiting the rate of further dissolution.
Initiation propagation and termination of elastodynamic ruptures associated with segmentation of faults and shaking hazard
Authors: Shaw Bruce E.
Published: August 2006

Using a model of a complex fault system, we examine the initiation, propagation, and termination of ruptures and their relationship to fault geometry and shaking hazard. We find concentrations of epicenters near fault step overs and ends; concentrations of terminations near fault ends; and persistent propagation directivity effects. Taking advantage of long sequences of dynamic events, we directly measure shaking hazards, such as peak ground acceleration exceedance probabilities, without need for additional assumptions. This provides a new tool for exploring shaking hazard from a physics‐based perspective, its dependence on various physical parameters, and its correlation with other geological and seismological observables. Using this capability, we find some significant aspects of the shaking hazard can be anticipated by measures of the epicenters. In particular, asymmetries in the relative peak ground motion hazard along the faults appear well correlated with asymmetries in epicentral locations.
Retrieving a common accumulation record from Greenland ice cores for the past 1800 years
Authors: Andersen K. K. , Ditlevsen P. D. , Rasmussen S. O. , Clausen H. B. , Vinther B. M. , Johnsen S. J. , Steffensen J. P.
Published: August 2006

In the accumulation zone of the Greenland ice sheet the annual accumulation rate may be determined through identification of the annual cycle in the isotopic climate signal and other parameters that exhibit seasonal variations. On an annual basis the accumulation rate in different Greenland ice cores is highly variable, and the degree of correlation between accumulation series from different ice cores is low. However, when using multiyear averages of the different accumulation records, the correlation increases significantly. A statistical model has been developed to estimate the common climate signal in the different accumulation records through optimization of the ratio between the variance of the common signal and of the residual. Using this model, a common Greenland accumulation record for the past 1800 years has been extracted. The record shows significant 11.9 years periodicity. A sharp transition to very dry conditions is found just before A.D. 1200, and very dry conditions during the 13th century together with dry and cold spells during the 14th century may have put extra strain on the Norse population in Greenland and may have contributed to their extinction. Accumulation rates gradually decrease from a distinct maximum in A.D. 1394 to very dry conditions in the late 17th century and thus reflect the Little Ice Age.
Line mixing and collision‐induced absorption by oxygen in the A band: Laboratory measurements, model, and tools for atmospheric spectra computations
Authors: Tran H. , Boulet C. , Hartmann J.‐M.
Published: August 2006

The absorption by oxygen in the region of the O2 A band near 760 nm has been measured in the laboratory under various conditions of pressure (20–200 atm) and temperature (200–300 K) for both pure O2 and O2‐N2 mixtures. In order to calculate the contribution of the “allowed” A band transitions, Lorentzian profiles and a model accounting for line‐mixing (LM) effects using the energy corrected sudden (ECS) approximation have been used. The differences between computed spectra and measured values enable extraction of the collision‐induced absorption (CIA) contribution. It is shown that neglecting line mixing overestimates absorption in the wings and underestimates absorption at the P and R branch peaks, whereas the CIA extracted by the line‐mixing approach shows the “smooth” profile expected. Applying this approach to our spectra enables determination of the CIA and allowed contributions for both O2‐O2 and O2‐N2 collisions versus temperature and pressure. The resulting model and data are then used to build a database and some software suitable for the calculation of oxygen (in air) atmospheric absorption and for easy inclusion in radiative transfer codes (available upon request). These tools are then applied to a theoretical study of the influences of both line‐mixing and collision‐induced processes on atmospheric photon path escape factors and on cloud‐top altitude retrievals. It is shown that LM and CIA make significant contributions and explain a large part of the discrepancies between measured and calculated atmospheric absorption observed recently.
Experimental channel response to tectonic uplift
Authors: Turowski Jens M. , Lague Dimitri , Crave Alain , Hovius Niels
Published: August 2006

We have performed a series of experiments to investigate the relationship between channel geometry and tectonic forcing in steady state landscapes at various uplift rates. The experimental setup consists of uniformly uplifted silica paste eroded by artificial rainfall. In this setup, erosional landscapes evolve by growth and amalgamation of incisions, which organize into a drainage network whose dynamics are a function of the interaction between vertical channel cutting, hillslope erosion, and sediment transport. High‐precision (0.5 mm pixel size) digital elevation models were constructed using a stereogrammetric camera system. From this data, channel bed slope was found to be independent of discharge and position on the experimental surface and to increase linearly with uplift rate. Geometric parameters of the flow, such as channel width or depth, could not be observed directly during the experiments. Using laminar flow equations for the mean flow velocity, these parameters were back calculated, and relationships to the imposed substrate uplift rate were derived. Channel width, cross‐sectional area, and wetted perimeter decrease with increasing uplift rate to a limit value, hydraulic radius and flow depth increase slightly, and flow velocity increases approximately linearly with increasing uplift rate. These results are qualitatively consistent with recent field surveys and highlight the importance of channel width and slope variations in accommodating channel response to variable rock uplift rates.
Geostatistical inference of hydraulic conductivity and dispersivities from hydraulic heads and tracer data
Authors: Nowak Wolfgang , Cirpka Olaf A.
Published: August 2006

In groundwater, hydraulic heads and solute arrival times depend primarily on the hydraulic conductivity field and hydraulic boundary conditions. The spread of breakthrough curves, in contrast, depends also on longitudinal and transverse dispersion coefficients. The shape of point‐like measured breakthrough curves can be reproduced by simulations only when appropriate dispersivities are applied. The values and spatial distributions of dispersivities depend on the resolution of the underlying hydraulic conductivity field. We present a geostatistical method for the joint estimation of log conductivity and log dispersivities from measurements of hydraulic heads and temporal moments of local breakthrough curves. The parameter fields are considered random space variables, and they are conditioned on the measurements by Bayesian inference. The estimated longitudinal and transverse dispersivities are to be applied in conjunction with the estimated conductivity field. We apply our technique to data of a technical‐scale tracer experiment. In the particular application, the amount and quality of measured data are sufficient to infer the conductivity distribution at a spatial resolution at which the spread of locally obtained breakthrough curves is dominated by pore‐scale transverse dispersion.
High‐precision isotopic characterization of USGS reference materials by TIMS and MC‐ICP‐MS
Authors: Weis Dominique , Kieffer Bruno , Maerschalk Claude , Barling Jane , de Jong Jeroen , Williams Gwen A. , Hanano Diane , Pretorius Wilma , Mattielli Nadine , Scoates James S. , Goolaerts Arnaud , Friedman Richard M. , Mahoney J. Brian
Published: August 2006

The Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia has undertaken a systematic analysis of the isotopic (Sr, Nd, and Pb) compositions and concentrations of a broad compositional range of U.S. Geological Survey (USGS) reference materials, including basalt (BCR‐1, 2; BHVO‐1, 2), andesite (AGV‐1, 2), rhyolite (RGM‐1, 2), syenite (STM‐1, 2), granodiorite (GSP‐2), and granite (G‐2, 3). USGS rock reference materials are geochemically well characterized, but there is neither a systematic methodology nor a database for radiogenic isotopic compositions, even for the widely used BCR‐1. This investigation represents the first comprehensive, systematic analysis of the isotopic composition and concentration of USGS reference materials and provides an important database for the isotopic community. In addition, the range of equipment at the PCIGR, including a Nu Instruments Plasma MC‐ICP‐MS, a Thermo Finnigan Triton TIMS, and a Thermo Finnigan Element2 HR‐ICP‐MS, permits an assessment and comparison of the precision and accuracy of isotopic analyses determined by both the TIMS and MC‐ICP‐MS methods (e.g., Nd isotopic compositions). For each of the reference materials, 5 to 10 complete replicate analyses provide coherent isotopic results, all with external precision below 30 ppm (2 SD) for Sr and Nd isotopic compositions (27 and 24 ppm for TIMS and MC‐ICP‐MS, respectively). Our results also show that the first‐ and second‐generation USGS reference materials have homogeneous Sr and Nd isotopic compositions. Nd isotopic compositions by MC‐ICP‐MS and TIMS agree to within 15 ppm for all reference materials. Interlaboratory MC‐ICP‐MS comparisons show excellent agreement for Pb isotopic compositions; however, the reproducibility is not as good as for Sr and Nd. A careful, sequential leaching experiment of three first‐ and second‐generation reference materials (BCR, BHVO, AGV) indicates that the heterogeneity in Pb isotopic compositions, and concentrations, could be directly related to contamination by the steel (mortar/pestle) used to process the materials. Contamination also accounts for the high concentrations of certain other trace elements (e.g., Li, Mo, Cd, Sn, Sb, W) in various USGS reference materials.
Observed intraseasonal variability of mini‐cold pool off the southern tip of India and its intrusion into the south central Bay of Bengal during summer monsoon season
Authors: Rao R. R. , Girish Kumar M. S. , Ravichandran M. , Samala B. K. , Anitha G.
Published: August 2006

The observed evolution of a mini‐cold pool (MCP) off the southern tip of India (STI) and its intrusion into the south central Bay of Bengal (BoB) during the summer monsoon season shows pronounced cooling episodes on intraseasonal time scale with differences in their number, intensity, duration and spatial extent. This variability that changes from year to year appears to be primarily determined by the corresponding variability in the upwelling driven by the divergence in the near‐surface (Ekman + geostrophic) circulation and wind induced mixing. The signature of this cooling carried by the Summer Monsoon Current (SMC) is seen with reduction in intensity in the south central BoB limited mostly only to south of about 10°N. In the background of slow cooling caused by SMC, the cooling episodes of different amplitudes occur in the south central BoB suggesting that spatially variable wind forcing is responsible for producing these episodes simultaneously on intraseasonal time scale.
Control of equatorial ionospheric morphology by atmospheric tides
Authors: Immel T. J. , Sagawa E. , England S. L. , Henderson S. B. , Hagan M. E. , Mende S. B. , Frey H. U. , Swenson C. M. , Paxton L. J.
Published: August 2006

A newly discovered 1000‐km scale longitudinal variation in ionospheric densities is an unexpected and heretofore unexplained phenomenon. Here we show that ionospheric densities vary with the strength of non‐migrating, diurnal atmospheric tides that are, in turn, driven mainly by weather in the tropics. A strong connection between tropospheric and ionospheric conditions is unexpected, as these upward propagating tides are damped far below the peak in ionospheric density. The observations can be explained by consideration of the dynamo interaction of the tides with the lower ionosphere (E‐layer) in daytime. The influence of persistent tropical rainstorms is therefore an important new consideration for space weather.
Long‐range triggered earthquakes that continue after the wave train passes
Authors: Brodsky Emily E.
Published: August 2006

Large earthquakes can trigger distant earthquakes in geothermal areas. Some triggered earthquakes happen while the surface waves pass through a site, but others occur hours or even days later. Does this prolonged seismicity require a special mechanism to store the stress from the seismic waves that differs from ordinary aftershock mechanisms? These questions have driven studies of long‐range triggering since the phenomenon's discovery. Here I attempt to answer the questions by examining the statistics of triggered sequences. Two separate observations are consistent with the prolonged sequences being simply local aftershocks of earthquakes triggered early in the wave train. First, the sequences obey Omori's Law over both short (1 hour) and longer (5 day) time intervals. Secondly, the number of observed triggered earthquakes in the first hour after the wave train can be predicted from the number of earthquakes triggered during the wave train. Even the very vigorous 10‐day triggering at Long Valley from the 1992 Landers Mw 7.3 earthquakes can be interpreted as the aftershocks of either a local M ≈ 4.1 earthquake or an equivalent combination of several smaller mainshocks. Therefore, long‐range triggering does not need to include a mechanism to produce sustained stresses other than the process that generates aftershocks of the earthquakes that occur while the wave train is passing.