bluuebunny/crossref_metadata_2025 huggingface dataset:
G
+
C
Content Evolution in the Human Genome
Authors: Li Wentian
Published: April 2013

The proportion of guanine (G) or cytosine (C) nucleotide bases in the human genome is approximately 40%. Fluctuating relatively to this averaged G+C content, there are large chromosomal regions with alternatingly high and low local G+C contents. The (G+C)‐rich genomic regions are typically gene rich, replicated earlier and higher in recombination activities. Many aspects of the evolution of base composition leading to the local G+C variations in the human genome have been debated, including the origin of the alternating G+C structure, whether (G+C)‐rich regions have been vanishing or emerging, what are the main mutational or nonmutational mechanisms driving the G+C content, whether G+C content is determined by neutral evolution or selection or both. A particularly promising scenario for G+C evolution is to consider the open and closed chromatin structures which naturally provide a differential mutational environment for different chromosome regions.

Key Concepts:

Human genome is characterised by alternatingly high and low G+C regions.

Such pattern of alternatingly high and low G+C regions is not unique for the human genome. It is also present in species which diverged from a common ancestor a few hundred millions years ago.

Both mutational and nonmutational mechanisms could be responsible for shaping the G+C content in human. The former creates new alleles with a changed G+C content, the latter biased transmits existing polymorphic alleles towards either higher or lower G+C.

The suggestion of natural selection playing a crucial role in maintaining high G+C regions is based on the observation that high G+C regions are also high in several biological activities (translation, transcription and recombination).

Chromatin structure may provide a differential mutational environment by being accessible (open) or inaccessible (closed) to other protein molecules.
The
GB
Viruses: An Update of Their Biology, Molecular Virology and Significance
Authors: Karayiannis P
Published: April 2013

In the quest to identify further viruses associated with hepatitis, three new viruses were cloned and assigned to the
Flaviviridae
family in the mid‐1990s. These were named the GB virus A (GBV‐A), GBV‐B and GBV‐C/hepatitis G virus (HGV). A more recent member is GBV‐D. Of these, GBV‐B, which is not a human pathogen, is associated with hepatitis in tamarins (
Saguinus
sp). GBV‐A, ‐C/HGV and ‐D, in turn, infect primates, humans and frugivorous bats. These three viruses, unlike GBV‐B, are characterised by the lack of an identifiable core protein and do not appear to be associated with any signs and symptoms of disease. Moreover, the liver does not appear to be the primary site of replication for GBV‐A and GBV‐C/HGV. Instead, the lymphoid system seems to be their primary target. The current review deals with what is known of the natural history, virology and molecular biology of these viruses.

Key Concepts:

GBV‐A, GBV‐B, GBV‐C/HGV and GBV‐D are members of the
Flaviviridae
family.

GBV‐B causes hepatitis only in tamarins (
Saguinus
sp).

GBV‐A, ‐C/HGV and ‐D are not associated with hepatitis.

GBV‐A and ‐C/HGV appear to replicate primarily in lymphocytes.

GBV‐A, ‐C/HGV and ‐D do not have an identifiable core‐encoding region in their genome.

GBV‐A and ‐C/HGV cause persistent infection.

Loss of GBV‐C/HGV viraemia is associated with the development of anti‐E2 antibodies.
Nonadaptive Genetic Change in Human and Primate Evolution
Authors: Meyer Diogo , Harris Eugene E
Published: April 2013

Evolutionary change can occur by nonadaptive processes, such as random genetic drift, and as a consequence of selection on linked genetic variants. In addition, if selective regimes change over time, an allele currently at a high frequency because of past fitness advantage may be suboptimal for its present environment. Small effective population size along the human lineage increased the influence of drift, rendering mutations with slight effects on fitness effectively neutral. Demographic events like spatial expansions and population bottlenecks shape most of the genetic variation within and among modern populations. Natural selection itself may also contribute to nonadaptive or maladaptive change by increasing the frequency of linked deleterious variants. Also, certain maladaptive alleles may have increased in frequency because of compensating fitness advantages they provide.

Key Concepts:

Reduced effective population size along the human lineage led to an increase in the influence of genetic drift and a reduction in the efficacy of natural selection, especially for mutations with small selective effects. Evidence for this can be seen in comparisons of measures of natural selection in lineages having different effective population sizes.

Genome‐wide variation within and between human populations can be almost entirely explained by random drift and demographic forces other natural selection.

Spatial expansions in human evolutionary history may cause gene surfing, in which low frequency alleles at the wave of advance can reach high frequencies and spread over large areas merely due to the effects of intense genetic drift. Nonadaptive gene surfing might be a better explanation than adaptive evolution for some high frequency, widespread genetic variants.

Population bottlenecks in human evolutionary history can lead to increases in drift and reductions in the efficacy of purifying selection. This leads to an increase in the fraction of slightly deleterious mutations present in human populations that have experienced recent bottlenecks.

Natural selection on alleles can result in nonadaptive shifts in the frequencies of alleles that are closely linked to them. Such linkage effects can lead to the increased frequencies of mildly deleterious alleles if they are linked to a beneficial variant, and can interfere with the effectiveness of adaptive evolution in promoting an advantageous allele if it is linked to a deleterious allele.

Caution should be exercised in interpreting patterns of genetic variation in human populations as being adaptive without thoroughly ruling out nonadaptive explanations.
Crystalline CoFeB/Graphite Interfaces for Carbon Spintronics Fabricated by Solid Phase Epitaxy
Authors: Wong P. K. Johnny , van Geijn Elmer , Zhang Wen , Starikov Anton A. , Tran T. Lan Anh , Sanderink Johnny G. M. , Siekman Martin H. , Brocks Geert , Kelly Paul J. , van der Wiel Wilfred G. , de Jong Michel P.
Published: April 2013

Structurally ordered interfaces between ferromagnetic electrodes and graphene or graphite are of great interest for carbon spintronics, since they allow spin‐filtering due to k‐vector conservation. By solid phase epitaxy of amorphous/nanocrystalline CoFeB at elevated temperatures, the feasibility of fabricating crystalline interfaces between a 3d ferromagnetic alloy and graphite is demonstrated, without suffering from the unwetting problem that was commonly seen in many previous studies with 3d transition metals. The films fabricated on graphite in this way are found to have a strong body‐centered‐cubic (110) texture, albeit without a unique, well‐defined in‐plane epitaxial relationship with the substrate lattice. Using various X‐ray spectroscopic techniques, it is shown that boron suppresses the formation of CoFe‐O during CoFeB deposition, and then diffuses out of the CoFe lattice. Segregation of B occurred exclusively to the film surface upon in situ annealing, and not to the interface between CoFeB and graphite. This is favorable for obtaining a high spin polarization at the hybrid CoFe/graphite crystalline interface. The Co and Fe spin moments in the crystalline film, determined by X‐ray magnetic circular dichroism, are found to be bulk‐like, while their orbital moments show an unusual giant enhancement which has yet to be understood.
Steady state modeling and simulation of the Oleflex process for isobutane dehydrogenation considering reaction network
Authors: Farsi M. , Jahanmiri A. , Rahimpour M. R.
Published: April 2013

In this study, the performance of moving bed radial flow reactors in Olefex technology to produce isobutene from isobutane dehydrogenation is studied at steady state condition. The dehydrogenation reactors have been modeled heterogeneously on the basis of the mass and energy governing laws considering a two‐dimensional model. In this system, isobutane dehydrogenation, hydrogenolysis, propane dehydrogenation, and coke formation reactions occur on the catalyst surface. The coke deposition on the catalyst surface and the catalyst velocity along the axial direction result to an activity profile along reactors that has been calculated from proper correlation. To prove the accuracy of the considered mathematical model and assumptions, simulation results are compared with the plant data at the same process condition. The isobutane conversion and isobutene selectivity have been obtained at about 38.53% and 90.76%, respectively, which have good agreement with the plant data. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.
Reactions of 13‐Vertex Carboranes with Strong Bases: Synthesis and Structural Characterization of Carborane Monoanions with exo‐π Bonding
Authors: Zheng Fangrui , Zhang Jian , Fu Xiaodu , Xie Zuowei
Published: April 2013

Several monoanions of 13‐vertex carboranes were prepared in high yields from the reactions of C,C′‐linked 13‐vertex carboranes with tBuOK or NaH in dry THF at room temperature. These monoanions were characterized by various spectroscopic methods, elemental analysis, and single‐crystal X‐ray diffraction. The results showed substantial double‐bond character between the cage‐carbon atom and the exo vicinal carbon atom, thus leading to charge delocalization into the cage. As a result, the atomatom distances within the cage were elongated, with one broken CB bond. However, the cage geometry of the monoanions remained very similar to that of their corresponding neutral 13‐vertex closo‐carboranes. These monoanions represent the first examples of 13‐vertex carboranes with exo‐π bonding to hypercarbon atoms.
Design of Robust Discrete‐Time Observer‐Based Repetitive‐Control System
Authors: Zhou Lan , She Jinhua , Zhou Shaowu , Wu Min
Published: April 2013

This paper concerns the design of a robust discrete‐time observer‐based repetitive‐control system for a class of linear plants with periodic uncertainties. A discrete two‐dimensional model is built that partially uncouples the control and learning actions of a repetitive‐control system, enabling their preferential adjustment. The combination of a singular‐value decomposition of the output matrix and Lyapunov stability theory is used to derive a linear‐matrix‐inequality‐based design algorithm that determines the control and state‐observer gains. A numerical example illustrates the main advantage of the method: easy, preferential adjustment of control and learning by means of two tuning parameters in an linear‐matrix‐inequality‐based condition.
Improvement of grand multi‐model ensemble prediction skills for the coupled models of APCC/ENSEMBLES using a climate filter
Authors: Lee Doo Young , Ahn Joong‐Bae , Ashok Karumuri , Alessandri Andrea
Published: April 2013

Twelve coupled model simulations of two multi‐model ensemble (MME) systems for boreal winters from 1983 to 2005 are used to improve the climate prediction. From grading the relative capability of each simulation in reproducing the observed link between the tropical El Niño‐Southern Oscillation (ENSO)‐related Walker circulation and the Pacific rainfall, we find an optimal MME suite with improved prediction skills. This study demonstrates that the climate filter concept, proposed by us in a recent work, is not only useful in improving the MME prediction skills as compared to a single MME system, but also the skills of a grand MME that encompasses two well‐performing MMEs.
Characteristics improvement of calcium hydroxide dental cement by hydroxyapatite nanoparticles. Part 1: Formulation and microstructure
Authors: Yasaei Mana , Zamanian Ali , Moztarzadeh Fathollah , Ghaffari Maryam , Mozafari Masoud
Published: April 2013

Calcium hydroxide cement (CHC), which is a direct pulp‐capping material, has been widely used for several decades. In spite of the well‐known advantages of CHCs, they have some disadvantages as well, such as high solubility, no inherent adhesive qualities, and low mechanical strength. Previous studies were undertaken to improve these deficiencies by implementing changes to modify the conventional CHCs. The aim of the present research is to demonstrate the potential rectification of the aforementioned deficiencies of the commercially available CHCs by adding hydroxyapatite (HA) nanoparticles without lessening their advantages. Here, the synthesized HA nanoparticles were added into the CHCs in two different portions of 3 and 7 wt%. A scanning electron microscope was used to observe and analyze the microstructure, and X‐ray energy dispersive analysis was used to analyze the elemental composition of the new CHCs. In addition, setting time, mechanical strength, pH, calcium (Ca) release, and antibacterial behavior were measured to assess how HA nanoparticles influence the characteristics of CHCs. The results showed that adding 3 wt% HA nanoparticles can optimally improve the mechanical strength of the cement and increase the Ca release rate as a mineralization promoter without reducing the antibacterial behavior.
President's page
Authors: Dillon Andrew
Published: April 2013

Editor's Summary

As the president of the newly renamed Association for Information Science & Technology, Dillon recognizes critical behind‐the‐scenes work being done to improve ASIS&T from the inside out. The Task Force on Web Presence will develop a plan to enhance internal communications and to keep information current and easy to find. Developing a moderated discussion forum on information will help solidify the organization's position as a thought leader. An information resource on what information professionals do will help define the field for public viewers and solicit thoughts on careers and opportunities. Recognizing the value of volunteer involvement, input and assistance, Dillon invites all ASIS&T members to participate actively at this turning point for the global association.
Open access and altmetrics: Distinct but complementary
Authors: Mounce Ross
Published: April 2013

Editor's Summary

Open access to publications through electronic journals has dramatically expanded downloading and use of this literature and spurred the rise of alternative metrics to assess article impact. Open access publications have been shown to gain more citations than articles with restricted access, and seven of the 10 most popular articles in 2012 were free public access with the most response, as documented through altmetrics, coming from non‐scientists. Altmetrics also enables post‐publication filtering and peer review in a nearly immediate timeframe for very large open access journals. Online activity measured through altmetrics highlights attention to the article on its own, less dependent on the validation of a journal name. The field of altmetrics is young, still limited to certain open websites, but with potential for considerable expansion, development and application. Open access and altmetrics can be expected to grow in a complementary and mutually supportive manner.
Collaborative annotation for scientific data discovery and reuse
Authors: Borne Kirk
Published: April 2013

Editor's Summary

Human classification alone, unable to handle the enormous quantity of project data, requires the support of automated machine‐based strategies. In collaborative annotation, humans and machines work together, merging editorial strengths in semantics and pattern recognition with the machine strengths of scale and algorithmic power. Discovery informatics can be used to generate common data models, taxonomies and ontologies. A proposed project of massive scale, the Large Synoptic Survey Telescope (LSST) project, will systematically observe the southern sky over 10 years, collecting petabytes of data for analysis. The combined work of professional and citizen scientists will be needed to tag the discovered astronomical objects. The tag set will be generated through informatics and the collaborative annotation efforts of humans and machines. The LSST project will demonstrate the development and application of a classification scheme that supports search, curation and reuse of a digital repository.
CNT‐Supported MoxC Catalysts: Effect of Loading and Carburization Parameters
Authors: Frank Benjamin , Friedel Klaus , Girgsdies Frank , Huang Xing , Schlögl Robert , Trunschke Annette
Published: April 2013

MoxC/CNT catalysts were prepared through carburization of an oxidic molybdenum precursor impregnated on multiwalled carbon nanotubes (CNTs). The effects of different carburization atmospheres, heating rates, and molybdenum loadings were tested. The catalysts were characterized by using CO temperature‐programmed desorption, XRD, N2physisorption, SEM, and TEM. The catalytic performance in the steam reforming of methanol was used as a sensitive probe to indicate changes in the catalyst surface during the catalytic action. Contrary to the bulk MoxC catalysts, the heating rate during carburization has no effect on the catalysts. Instead, molybdenum loading and carburization atmosphere are the key factors for catalyst structure and performance. The molybdenum‐based activity decreases at loadings >10 wt % at a constant product selectivity. The CO2/CH4product ratio indicates changes in the catalyst properties at the loadings <20 wt %, at which the activity is constant. Carburization in 20 % CH4/H2yields 2 nm sized crystallites of cubic α‐MoC. Carburization in pure H2and He yields hexagonal β‐Mo2C with a larger particle size. Both phases show different catalytic performances in terms of activity and CO2/CH4selectivity. Thus, a multiparameter toolbox for fine‐tuning of catalyst properties is presented.
A Combined Kinetic and Thermodynamic Approach for the Interpretation of Continuous‐Flow Heterogeneous Catalytic Processes
Authors: Bortolini Olga , Cavazzini Alberto , Giovannini Pier Paolo , Greco Roberto , Marchetti Nicola , Massi Alessandro , Pasti Luisa
Published: April 2013

The heterogeneous proline‐catalyzed aldol reaction was investigated under continuous‐flow conditions by means of a packed‐bed microreactor. Reaction‐progress kinetic analysis (RPKA) was used in combination with nonlinear chromatography for the interpretation, under synthetically relevant conditions, of important mechanistic aspects of the heterogeneous catalytic process at a molecular level. The information gathered by RPKA and nonlinear chromatography proved to be highly complementary and allowed for the assessment of optimal operating variables. In particular, the determination of the rate‐determining step was pivotal for optimizing the feed composition. On the other hand, the competitive product inhibition was responsible for the unexpected decrease in the reaction yield following an apparently obvious variation in the feed composition. The study was facilitated by a suitable 2D instrumental arrangement for simultaneous flow reaction and online flow‐injection analysis.
Methylidene Rare‐Earth‐Metal Complex Mediated Transformations of CN, NN and NH Bonds: New Routes to Imido Rare‐Earth‐Metal Clusters
Authors: Hong Jianquan , Zhang Lixin , Wang Kai , Zhang Yin , Weng Linhong , Zhou Xigeng
Published: April 2013

Three new patterns of reactivity of rare‐earth metal methylidene complexes have been established and thus have resulted in access to a wide variety of imido rare‐earth metal complexes [L3Ln3(μ2‐Me)3(μ3‐Me)(μ‐NR)] (L=[PhC(NC6H3iPr2‐2,6)2]−; R=Ph, Ln=Y (2 a), Lu (2 b); R=2,6‐Me2C6H3, Ln=Y (3 a), Lu (3 b); R=p‐ClC6H4, Ln=Y (4 a), Lu (4 b); R=p‐MeOC6H4, Ln=Y (5 a), Lu (5 b); R=Me2CHCH2CH2, Ln=Y (6 a), Lu (6 b)) and [{L3Lu3(μ2‐Me)3(μ3‐Me)}2(μ‐NR′N)] (R′=(CH2)6 (7 b), (C6H4)2 (8 b)). Complex 2 b was treated with an excess of CO2 to give the corresponding carboxylate complex [L3Lu3(μ‐η1:η1‐O2CCH3)3(μ‐η1:η2‐O2C‐CH3)(μ‐η1:η1:η2‐O2CNPh)] (9 b) easily. Complex 2 a could undergo the selective μ3‐Me abstraction reaction with phenyl acetylene to give the mixed imido/alkynide complex [L3Y3(μ2‐Me)3(μ3‐η1:η1:η3‐NPh)(μ3‐CCPh)] (10 a) in high yield. Treatment of 2 with one equivalent of thiophenol gave the selective μ3‐methyl‐abstracted products [L3Ln3(μ2‐Me)3(μ3‐η1:η1:η3‐NPh)(μ3‐SPh)] (Ln=Y (11 a); Lu (11 b). All new complexes have been characterized by elemental analysis, NMR spectroscopy, and most of the structures confirmed by X‐ray diffraction.
A Versatile and Robust Vesicle Based on a Photocleavable Surfactant for Two‐Photon‐Tuned Release
Authors: Dong Jianming , Xun Zhiqing , Zeng Yi , Yu Tianjun , Han Yongbin , Chen Jinping , Li Ying‐Ying , Yang Guoqiang , Li Yi
Published: April 2013

A small amphiphile that contains a coumarin unit and alkynyl groups, as a two‐photon‐cleavable segment and polymerizable groups, respectively, was designed and synthesized. The amphiphile showed a critical aggregation concentration of about 4.6×10−5 M and formed a vesicle‐type assembly. The formed vesicles were stabilized by in situ “click” polymerization without altering their morphology. Hydrophobic and hydrophilic guests can be encapsulated within the vesicle membrane and inside the aqueous core of the vesicle, respectively. The loaded guests can be released from the vesicle by using UV or near‐IR stimuli, through splitting up the amphiphilic structure of the amphiphile. Distinguished dose‐controlled photorelease of the polymeric vesicle is achieved with the maintenance of vesicular integrity, which makes the guest release dependent on the amount of cleavage of the amphiphilic structure during irradiation. This study provides a potential strategy for the development of versatile and stable drug‐delivery systems that offer sustained and photo‐triggered release.
Total Synthesis of Nominal Gobienine A
Authors: Kondoh Azusa , Arlt Alexander , Gabor Barbara , Fürstner Alois
Published: April 2013

The lichen‐derived glycoconjugate gobienine A is structurally more complex than most glycolipids isolated from higher plants by virtue of the all‐cis substituted γ‐lactone substructure embedded into its macrocyclic frame. A concise entry into this very epimerization‐prone and hence challenging structural motif is presented, which relies on an enantioselective cyanohydrin formation, an intramolecular Blaise reaction, a palladium‐catalyzed alkoxycarbonylation, and a diastereoselective hydrogenation of the tetrasubstituted alkene in the resulting butenolide. This strategy, in combination with ring‐closing olefin metathesis for the formation of the macrocyclic perimeter, allowed the proposed structure of gobienine A (1) to be formed in high overall yield. The recorded spectral data show that the structure originally attributed to gobienine A is incorrect and that it is not the epimerization‐prone ester site on the butanolide ring that is the locus of misassignment; rather, the discrepancy must be more profound.
MAO Inhibitory Activity of 2‐Arylbenzofurans versus 3‐Arylcoumarins: Synthesis, in vitro Study, and Docking Calculations
Authors: Ferino Giulio , Cadoni Enzo , Matos Maria João , Quezada Elias , Uriarte Eugenio , Santana Lourdes , Vilar Santiago , Tatonetti Nicholas P. , Yáñez Matilde , Viña Dolores , Picciau Carmen , Serra Silvia , Delogu Giovanna
Published: April 2013

Monoamine oxidase (MAO) is an important drug target for the treatment of neurological disorders. Several 3‐arylcoumarin derivatives were previously described as interesting selective MAO‐B inhibitors. Preserving the trans‐stilbene structure, a series of 2‐arylbenzofuran and corresponding 3‐arylcoumarin derivatives were synthesized and evaluated as inhibitors of both MAO isoforms, MAO‐A and MAO‐B. In general, both types of derivatives were found to be selective MAO‐B inhibitors, with IC50 values in the nano‐ to micromolar range. 5‐Nitro‐2‐(4‐methoxyphenyl)benzofuran (8) is the most active compound of the benzofuran series, presenting MAO‐B selectivity and reversible inhibition (IC50=140 nM). 3‐(4′‐Methoxyphenyl)‐6‐nitrocoumarin (15), with the same substitution pattern as that of compound 8, was found to be the most active MAO‐B inhibitor of the coumarin series (IC50=3 nM). However, 3‐phenylcoumarin 14 showed activity in the same range (IC50=6 nM), is reversible, and also severalfold more selective than compound 15. Docking experiments for the most active compounds into the MAO‐B and MAO‐A binding pockets highlighted different interactions between the derivative classes (2‐arylbenzofurans and 3‐arylcoumarins), and provided new information about the enzyme–inhibitor interaction and the potential therapeutic application of these scaffolds.
Homogeneous Electrochemical Detection of Hippuric Acid in Urine Based on the Osmium–Antigen Conjugate
Authors: Jeon Won‐Yong , Choi Young‐Bong , Kim Hyug‐Han
Published: April 2013

A homogeneous electrochemical immunoassay is based on the interaction of osmium–antigen conjugate with its antibody. The novelty presented herein is the direct conjugation of the osmium complex to a small antigen and the application of the quantitative analysis of the antigen and its antibody as the electrical signal for homogeneous immunoassay. The small antigen chosen is hippuric acid (HA), a major urinary metabolite in toluene‐exposed humans. As a redox mediator, [Os(4,4′‐dimethoxy‐2,2′‐bipyridine)2(4‐aminomethylpyridine‐HA)Cl]+/2+ (Os‐HA antigen) has been synthesized and characterized on screen‐printed carbon electrodes. The synthesized Os‐HA antigen shows reversible redox peaks at E1/2=0.056 V versus Ag/AgCl. The homogeneous competitive immunoassay relies on the interaction between Os‐HA antigen conjugate and free antigen to its antibody, which can generate electrical signals linearly proportional to the free antigen monitored by cyclic voltammetry and differential pulse voltammetry in the range of 10 μg mL−1 to 5.12 mg mL−1. The cutoff concentration of HA in urine samples is 2.0 mg mL−1, so the method can be used to develop a HA immunosensor. Moreover, the proposed homogeneous electrochemical immunoassay method can be applied to detect low concentrations of small antigens found in the healthcare area.
Direct Bio‐electrocatalysis of O2 Reduction by Streptomyces coelicolor Laccase Orientated at Promoter‐Modified Graphite Electrodes
Authors: Lörcher Samuel , Lopes Paula , Kartashov Andrey , Ferapontova Elena E.
Published: April 2013

Bacterial laccase from Streptomyces coelicolor (SLAC) has been immobilised and orientated at promoter (pyrene and neocuproine)‐modified electrodes productively both for direct electron transfer (ET) between the electrode and the T1 Cu site of SLAC and direct (unmediated) bio‐electrocatalysis of dioxygen reduction. Its T1 Cu potential ranges between 471 and 318 mV versus the normal hydrogen electrode, at pH 5.5 and 8, respectively; this value is dependent both on the solution pH and electrode modification. In the presence of O2, Cu of the T2/T3 trinuclear centre is distinguished electrochemically at 748–623 mV. Depending on the promoter nature, different orientations of SLAC at pyrene‐ and neocuproine‐modified electrodes can be followed from the kinetic analysis of the ET rates. Bio‐electrocatalytic reduction of oxygen starts from the T1 Cu potentials of SLAC, and is most efficient at the promoter‐modified electrodes, thereby demonstrating good performance both in neutral and basic media and in solutions with a high NaCl content, such as sea water. The obtained results allow consideration of a broader bioenergetic application of laccases as biocathodes operating directly in such environmental media as sea water and physiological fluids.
Electron Interference in Molecular Photoionization by Attosecond Laser Pulses
Authors: Yuan Kai‐Jun , Lu Huizhong , Bandrauk André D.
Published: April 2013

Molecular photoionization by intense attosecond linearly and circularly polarized X‐ray laser pulses is investigated from numerical solutions of time‐dependent Schrödinger equations for the one‐electron systems H2+ and H3++. Both momentum stripes and rings in photoelectron angular distributions are observed. The first with momentum intervals Δps=2 π/R, where R is the molecular internuclear distance, results from interference of the coherent continuum scattering electron wave packets, which is shown to be insensitive to the laser polarization and wavelength. Diffraction of the directly ionized electrons leads to the momentum rings defined by the angle ${\theta _{p^r R} = \cos ^{ - 1} \left( {2n\pi } \right)/p^r R}$ between the electron momentum pr and the molecular internuclear R axis. These patterns are well described by multi‐center interference models. Such complex patterns allow us to probe intermolecular structures.
Parkinson Disease and Exercise
Authors: Earhart Gammon M. , Falvo Michael J.
Published: April 2013

Parkinson disease (PD) is a progressive, neurodegenerative movement disorder. PD was originally attributed to neuronal loss within the substantia nigra pars compacta, and a concomitant loss of dopamine. PD is now thought to be a multisystem disorder that involves not only the dopaminergic system, but other neurotransmitter systems whose role may become more prominent as the disease progresses (). PD is characterized by four cardinal symptoms, resting tremor, rigidity, bradykinesia, and postural instability, all of which are motor. However, PD also may include any combination of a myriad of nonmotor symptoms (). Both motor and nonmotor symptoms may impact the ability of those with PD to participate in exercise and/or impact the effects of that exercise on those with PD. This article provides a comprehensive overview of PD, its symptoms and progression, and current treatments for PD. Among these treatments, exercise is currently at the forefront. People with PD retain the ability to participate in many forms of exercise and generally respond to exercise interventions similarly to age‐matched subjects without PD. As such, exercise is currently an area receiving substantial research attention as investigators seek interventions that may modify the progression of the disease, perhaps through neuroprotective mechanisms. © 2013 American Physiological Society.Compr Physiol3:833‐848, 2013.
Liver Immunology
Authors: Bogdanos Dimitrios P. , Gao Bin , Gershwin M. Eric
Published: April 2013

The liver is the largest organ in the body and is generally regarded by nonimmunologists as having little or no lymphoid function. However, such is far from accurate. This review highlights the importance of the liver as a lymphoid organ. Firstly, we discuss experimental data surrounding the role of liver as a lymphoid organ. The liver facilitates tolerance rather than immunoreactivity, which protects the host from antigenic overload of dietary components and drugs derived from the gut and it is instrumental to fetal immune tolerance. Loss of liver tolerance leads to autoaggressive phenomena, which if not controlled by regulatory lymphoid populations, may lead to the induction of autoimmune liver diseases. Liver‐related lymphoid subpopulations also act as critical antigen‐presenting cells. The study of the immunological properties of liver and delineation of the microenvironment of the intrahepatic milieu in normal and diseased livers provides a platform to understand the hierarchy of a series of detrimental events that lead to immune‐mediated destruction of the liver and the rejection of liver allografts. The majority of emphasis within this review will be on the normal mononuclear cell composition of the liver. However, within this context, we will discuss selected, but not all, immune‐mediated liver disease and attempt to place these data in the context of human autoimmunity. © 2013 American Physiological Society.Compr Physiol3:567‐598, 2013.
Renal Vascular Structure and Rarefaction
Authors: Chade Alejandro R.
Published: April 2013

An intact microcirculation is vital for diffusion of oxygen and nutrients and for removal of toxins of every organ and system in the human body. The functional and/or anatomical loss of microvessels is known as rarefaction, which can compromise the normal organ function and have been suggested as a possible starting point of several diseases. The purpose of this overview is to discuss the potential underlying mechanisms leading to renal microvascular rarefaction, and the potential consequences on renal function and on the progression of renal damage. Although the kidney is a special organ that receives much more blood than its metabolic needs, experimental and clinical evidence indicates that renal microvascular rarefaction is associated to prevalent cardiovascular diseases such as diabetes, hypertension, and atherosclerosis, either as cause or consequence. On the other hand, emerging experimental evidence using progenitor cells or angiogenic cytokines supports the feasibility of therapeutic interventions capable of modifying the progressive nature of microvascular rarefaction in the kidney. This overview will also attempt to discuss the potential renoprotective mechanisms of the therapeutic targeting of the renal microcirculation. © 2013 American Physiological Society.Compr Physiol3:817‐831, 2013.
Immune and Inflammatory Role in Renal Disease
Authors: Imig John D. , Ryan Michael J.
Published: April 2013

Chronic and acute renal diseases, irrespective of the initiating cause, have inflammation and immune system activation as a common underlying mechanism. The purpose of this review is to provide a broad overview of immune cells and inflammatory proteins that contribute to the pathogenesis of renal disease, and to discuss some of the physiological changes that occur in the kidney as a result of immune system activation. An overview of common forms of acute and chronic renal disease is provided, followed by a discussion of common therapies that have anti‐inflammatory or immunosuppressive effects in the treatment of renal disease. © 2013 American Physiological Society.
Compr Physiol
3:957‐976, 2013.
Lanthanide‐Functionalized SBA‐15 Mesoporous Hybrids – Ultraviolet‐Visible Excitation and Visible–NIR Emission
Authors: Gu Yan‐Jing , Yan Bing
Published: April 2013

9‐Hydroxy‐2‐methyl‐phenalenone (MHPO) was synthesized and modified with 3‐(triethoxysilyl)propyl isocyanate (TEPIC) through a hydrogen atom addition reaction to achieve a new chemical linkage (named as MHPOSi). SBA‐15 mesoporous silica organically functionalized with MHPOSi was synthesized. The MHPOSi was linked to tetraethoxysilane (TEOS) through a condensation process in the presence of Pluronic P123 surfactant as a template. New Ln3+ (Eu3+, Nd3+, Yb3+) organic–inorganic mesoporous hybrid materials were prepared, in which the Ln3+ complexes are covalently attached to SBA‐15 and have 1,10‐phenanthroline (phen) as a second ligand. The resultant mesoporous hybrids were characterized by FTIR spectroscopy, small‐angle X‐ray diffraction, N2 adsorption–desorption measurements, thermal analysis, and UV/Vis spectroscopy. They all have high surface areas, uniform mesostructures, and good crystallinity. The photophysical properties of the functionalized mesoporous SBA‐15 networks are discussed in detail and they still present excitation capability in the visible region despite the modification of the organic silane. Subsequently, they exhibit characteristic visible (Eu3+) and near‐infrared (NIR) luminescence (Nd+ and Yb3+).
Concise Chemoenzymatic Three‐Step Total Synthesis of Isosolenopsin through Medium Engineering
Authors: Simon Robert C. , Fuchs Christine S. , Lechner Horst , Zepeck Ferdinand , Kroutil Wolfgang
Published: April 2013

A short and efficient total synthesis of the alkaloid isosolenopsin and its enantiomer has been achieved. The key step was a ω‐transaminase‐catalysed regioselective monoamination of the diketone pentadecane‐2,6‐dione, which was obtained in a single step through the application of a Grignard reaction. Initial low conversions in the biotransformation could be overcome by optimisation of the reaction conditions employing suitable cosolvents. In the presence of 20 vol.‐% N,N‐dimethylformamide (DMF) or n‐heptane the best results were obtained by employing two enantiocomplementary ω‐transaminases originating from Arthrobacter at 30–40 °C; under these conditions, conversions of more than 99 % and perfect stereocontrol (ee > 99 %) were achieved. Diastereoselective chemical reduction (H2/Pd/C) of the biocatalytic product gave the target compound. The linear three‐step synthesis provided the natural product isosolenopsin in diastereomerically pure form (ee > 99 %, dr = 99:1) with an overall yield of 64 %.
Conithiaquinones A and B, Tetracyclic Cytotoxic Meroterpenes from the Mediterranean Ascidian Aplidium conicum
Authors: Menna Marialuisa , Aiello Anna , D'Aniello Filomena , Imperatore Concetta , Luciano Paolo , Vitalone Rocco , Irace Carlo , Santamaria Rita
Published: April 2013

Chemical investigation of the Mediterranean ascidian A. conicum resulted in the isolation of two new meroterpenes, the conithiaquinones A (1) and B (2), in addition to two previously reported chromenols (3 and 4) and conicaquinones (5 and 6). The structures of conithiaquinones A and B were determined by interpretation of spectroscopic data, and regiochemical and stereochemical assignments were achieved with the aid of computational methods, including the recently developed DP4 NMR spectral prediction method. Both conithiaquinones A and B showed significant effects on the growth and viability of cells, with 1 showing interesting cytotoxicity against human breast cancer cells.
Highly Selective and Sensitive Graphene Based Electrochemical Sensor for Quantification of Receptor Agonist Rizatriptan
Authors: Jain Rajeev , Tiwari D.C , Pandey Preeti
Published: April 2013

A highly selective and sensitive electrochemical sensor has been developed by modification of a glassy carbon electrode (GCE) with graphene (GRP) for quantification of Rizatriptan. The significant increase of the peak current and the improvement of the oxidation peak potential indicate that the electrochemical sensor facilitates the electron transfer of Rizatriptan. The oxidation peak current was proportional to the Rizatriptan concentration in the range from 100 to 600 µg/mL with detection (LOD) and quantification limit (LOQ) of 36.52 and 121.73 µg/mL, respectively. The developed method was successfully employed for quantification of Rizatriptan in pharmaceutical formulations. The sensor shows great promise for simple, sensitive and quantitative detection of Rizatriptan.
Assessment of stretched vortex subgrid‐scale models for LES of incompressible inhomogeneous turbulent flow
Authors: Shetty Dinesh A. , Frankel Steven H.
Published: April 2013

The physical space version of the stretched vortex subgrid scale model is tested in LES of the turbulent lid‐driven cubic cavity flow. LES is carried out by using a higher order finite‐difference method. The effects of different vortex orientation models and subgrid turbulence spectrums are assessed through comparisons of the LES predictions against DNS. Three Reynolds numbers 12000, 18000, and 22000 are studied. Good agreement with the DNS data for the mean and fluctuating quantities is observed. Copyright © 2013 John Wiley & Sons, Ltd.
Multistage collapse of eight western Canary Island landslides in the last 1.5 Ma: Sedimentological and geochemical evidence from subunits in submarine flow deposits
Authors: Hunt J. E. , Wynn R. B. , Talling P. J. , Masson D. G.
Published: April 2013

Volcaniclastic turbidites in the Madeira Abyssal Plain provide a record of major landslides from the Western Canary Islands in the last 1.5 Ma. These volcaniclastic turbidites are composed of multiple fining‐upward turbidite sands, known as subunits. The subunits indicate that the landslides responsible for the sediment gravity flows occurred in multiple stages. The subunits cannot result from flow reflection or splitting because the compositions of volcanic glasses from each individual subunit in an event bed are subtly different. This indicates that each subunit represents a discrete failure as part of a multistage landslide. This has significant implications for geohazard assessments, as multistage failures reduce the magnitude of the associated tsunami. The multistage failure mechanism reduces individual landslide volumes from up to 350 km3 to less than 100 km3. Thus although multistage failure ultimately reduce the potential landslide and tsunami threat, the landslide events may still generate significant tsunamis close to source.
A new seismogeodetic approach applied to GPS and accelerometer observations of the 2012 Brawley seismic swarm: Implications for earthquake early warning
Authors: Geng Jianghui , Bock Yehuda , Melgar Diego , Crowell Brendan W. , Haase Jennifer S.
Published: April 2013

The 26 August 2012 Brawley seismic swarm of hundreds of events ranging from M1.4 to M5.5 in the Salton Trough, California provides a unique data set to investigate a new seismogeodetic approach that combines Global Positioning System (GPS) and accelerometer observations to estimate displacement and velocity waveforms. First in simulated real‐time mode, we analyzed 1–5 Hz GPS data collected by 17 stations fully encircling the swarm zone at near‐source distances up to about 40 km using precise point positioning with ambiguity resolution (PPP‐AR). We used a reference network of North American GPS stations well outside the region of deformation to estimate fractional‐cycle biases and satellite clock parameters, which were then combined with ultrarapid orbits from the International GNSS Service to estimate positions during the Brawley seismic swarm. Next, we estimated seismogeodetic displacements and velocities from GPS phase and pseudorange observations and 100–200 Hz accelerations collected at three pairs of GPS and seismic stations in close proximity using a new tightly coupled Kalman filter approach as an extension of the PPP‐AR process. We can clearly discern body waves in the velocity waveforms, including P‐wave arrivals not detectable with the GPS‐only approach for earthquake magnitudes as low as Mw 4.6 and significant static offsets for magnitudes as low as Mw 5.4. Our study shows that GPS networks upgraded with strong motion accelerometers can provide new information for improved understanding of the earthquake rupture process and be of critical value in creating a robust early warning system for any earthquake of societal significance.
Blood pro‐inflammatory cytokines in Alzheimer's disease in relation to the use of acetylcholinesterase inhibitors
Authors: Richardson Cassandra , Gard Paul R. , Klugman Anthony , Isaac Mokhtar , Tabet Naji
Published: April 2013

Objective

A potential anti‐inflammatory role for acetylcholinesterase inhibitors (AChEIs) has been supported by animal studies. As very limited data exist from individuals with Alzheimer's disease (AD), the aim of this study was to assess the potential influence of AChEIs on blood pro‐inflammatory cytokines. We hypothesized that pro‐inflammatory cytokine concentrations were lower in individuals with AD stabilized on AChEIs.

Methods

Blood interleukin‐1 beta, interleukin‐6, and tumor necrosis factor‐alpha concentrations were assessed using specific enzyme‐linked immunosorbent assays in three groups of participants: patients with AD stabilized on a therapeutic dose of an AChEI (n = 42); AChEIs drug naïve patients (n = 24); and a cognitively unimpaired control group (n = 35). Patients in the AChEIs group had received medication for an average of one year.

Results

Patients stabilized on an AChEI did not differ significantly from drug naïve patients in relation to the concentrations of interleukin‐1 beta, interleukin‐6, and tumor necrosis factor‐alpha (p = 0.874, 0.225, and 0.978, respectively). Within the group taking AChEIs, the levels of cytokines did not differ between those taking donepezil, rivastigmine, or galantamine (p = 0.368, 0.851, and 0.299, respectively).

Conclusions

Results from animal studies suggesting a modulatory anti‐inflammatory role for AChEIs was not advanced in this study. In individuals with AD, very limited evidence currently exists to support the hypothesis that AChEIs may influence inflammatory blood markers and function beyond the enhancement of neuronal transmission. However, further studies assessing a wider range of inflammatory markers and processes are still needed before this hypothesis can be ruled out. Copyright © 2013 John Wiley & Sons, Ltd.
An experimental study of the influence of graphite on the electrical conductivity of olivine aggregates
Authors: Wang Duojun , Karato Shun‐ichiro , Jiang Zhenting
Published: April 2013

Presence of graphite is one of the mechanisms to explain enhanced electrical conductivity. Because the conductivity of graphite is highly anisotropic and the connectivity of graphite depends strongly on the geometry of the crystals, the key issue is the geometry of graphite in a rock including their crystallographic orientation and the shape of graphite crystals. We explored the role of graphite on electrical conductivity in olivine‐rich aggregates. To obtain well‐defined results, we conducted an experimental study at high pressure and temperature conditions. Olivine aggregates containing diamonds were annealed to transform diamond to graphite with nearly equilibrium morphology. Graphite formed by the transformation from diamond has thin disk‐shape morphology, the plane being the highly conductive (0001) plane. When the concentration of graphite exceeds the percolation threshold (~ 1 wt%), electrical conductivity is significantly enhanced. Some of the observed high conductivity regions may represent regions of high concentration of graphite.
Buoyant currents arrested by convective dissolution
Authors: MacMinn Christopher W. , Juanes Ruben
Published: April 2013

When carbon dioxide (CO2) dissolves into water, the density of water increases. This seemingly insubstantial phenomenon has profound implications for geologic carbon sequestration. Here we show, by means of laboratory experiments with analog fluids, that the up‐slope migration of a buoyant current of CO2 is arrested by the convective dissolution that ensues from a fingering instability at the moving CO2‐groundwater interface. We consider the effectiveness of convective dissolution as a large‐scale trapping mechanism in sloping aquifers, and we show that a small amount of slope is beneficial compared to the horizontal case. We study the development and coarsening of the fingering instability along the migrating current and predict the maximum migration distance of the current with a simple sharp‐interface model. We show that convective dissolution exerts a powerful control on CO2 plume dynamics and, as a result, on the potential of geologic carbon sequestration.