bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental investigation of sediment resuspension beneath internal solitary waves of depression
Authors: Aghsaee Payam , Boegman Leon
Published: April 2015

Internal solitary waves (ISWs) of depression are common features of coastal environments and believed to resuspend sediments where they shoal. In this study, the sediment resupension process associated with ISWs propagating over a flat bed was investigated in the laboratory. The first‐ever profile measurements of the three‐dimensional instantaneous velocity field beneath the ISWs revealed that resuspension occurs during burst like vertical velocity events, which lift sediments into the water column, in the adverse pressure gradient region beneath the trailing part of the wave. Resuspension was not observed when the wave‐induced viscous bed stress was maximal directly beneath the ISW trough. Prediction of wave‐induced resuspension was, therefore, unsuccessful using a traditional viscous bed stress‐based Shields diagram. A parameterization for ISW‐induced resuspension is proposed as a function of the maximum instantaneous vertical velocity in the bursts
. Here we have replaced the viscous bed stress with
, where
is the instantaneous resuspending bed stress and
is the near‐bed fluid density. From these results, it is possible for field‐oceanographers to predict the occurrence of ISW‐induced resuspension from the bulk wave and stratifications characteristics in a two‐layer stratification. Further research is required to extend the parameterization to larger Reynolds numbers at field‐scale.
Beam attenuation, scattering and backscattering of marine particles in relation to particle size distribution and composition in Hudson Bay (Canada)
Authors: Xi Hongyan , Larouche Pierre , Michel Christine , Tang Shilin
Published: April 2015

This study investigated the relationships between the concentration of biogeochemical parameters and particulate beam attenuation (cp), scattering (bp), and backscattering (bbp) in Hudson Bay. Results showed that most of the variability resulted from the presence of a deep chlorophyll maximum. cp, bp, and bbp were all adequate proxies to estimate total suspended matter (TSM) but were mostly sensitive to particulate inorganic matter (PIM) in the surface layer, and particulate organic matter (POM) at the chlorophyll maximum depth. The backscattering ratio
varied in the range of 0.005–0.05 and was inversely related to the POM : TSM ratio. According to the Twardowski et al. (2001) model, the PSD slope ξ well represented
and bulk refractive index
in relation to particulate composition. For inorganic particulate dominated waters, both
and
had a larger range and a higher mean value than at organic particulate dominated waters. This knowledge on the optical properties related to the PSD and particulate composition provides valuable information for further investigation and broadens our understanding of ocean optics in high latitude waters leading to potential improvements of regional scale remote sensing algorithms.
Climatology of cloud water content associated with different cloud types observed by A‐Train satellites
Authors: Huang Lei , Jiang Jonathan H. , Wang Zhien , Su Hui , Deng Min , Massie Steven
Published: April 2015

This study investigates the climatology of vertical distributions of cloud liquid water content, ice water content, and cloud fraction (CFR) associated with eight different cloud types, by utilizing the combined CloudSat radar and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar measurements. The geographical and seasonal variations of these cloud properties for each cloud type are also analyzed. The cloud water content (CWC) of each cloud type is sorted by three parameters obtained from colocated satellite observations to investigate the relationships between large‐scale conditions and the vertical structure of clouds. Results show that different cloud types have different altitudes of CWC and CFR peaks, and the altitude of CFR peak does not always overlap with that of CWC peak. Each type of cloud shows a clear asymmetric pattern of spatial distribution between Northern Hemisphere (NH) and Southern Hemisphere (SH). Stratocumulus and stratus clouds make the greatest contribution to the liquid water path, while the ice water path is mostly contributed by deep convective cloud over the tropics and nimbostratus over the middle and high latitudes. Over both middle and high latitudes, clouds have larger seasonal variation in the NH than in the SH. Over ocean, large CWCs of deep convective cloud, cirrus, and altostratus are above 7 km, and are associated with high convective available potential energy (>2000 J/kg), warm sea surface temperature (>303 K), and relatively high precipitation (>1 mm/h). Over land, most of the middle and high clouds have similar CWC distributions compared to those over ocean, but altocumulus and low clouds are quite different from those over ocean.
Magnetic and geochemical characterization of Andosols developed on basalts in the Massif Central, France
Authors: Grison Hana , Petrovsky Eduard , Stejskalova Sarka , Kapicka Ales
Published: April 2015

Identification of Andosols is primarily based upon the content of their colloidal constituents—clay and metal‐humus complexes—and on the determining of andic properties. This needs time and cost‐consuming geochemical analyses. Our primary aim of this study is to describe the magnetic and geochemical properties of soils rich in iron oxides derived from strongly magnetic volcanic basement (in this case Andosols). Secondary aim is to explore links between magnetic and chemical parameters of andic soils with respect to genesis factors: parent material age, precipitation, and thickness of the soil profile. Six pedons of andic properties, developed on basaltic lavas, were analyzed down to parent rock by a set of magnetic and geochemical methods. Magnetic data of soil and rock samples reflect the type, concentration, and particle‐size distribution of ferrimagnetic minerals. Geochemical data include soil reaction (pH in H2O), cation exchange capacity, organic carbon, and different forms of extractable iron and aluminum content. Our results suggest the following: (1) magnetic measurements of low‐field mass‐specific magnetic susceptibility can be a reliable indicator for estimating andic properties, and in combination with thermomagnetic curves may be suitable for discriminating between alu‐andic and sil‐andic subtypes. (2) In the studied Andosols, strong relationships were found between (a) magnetic grain‐size parameters, precipitation, and exchangeable bases; (b) concentration of ferrimagnetic particles and degree of crystallization of free iron; and (c) parameters reflecting changes in magneto‐mineralogy and soil genesis (parent material age + soil depth).
Selenocysteine
Authors: Rother Michael
Published: April 2015

The trace element selenium is present in the form of selenocysteine in selected proteins of organisms from all three domains of life. Most of the selenoproteins (i.e. proteins containing selenocysteine) investigated thus far are oxidoreductases with selenocysteine present in the active site and playing a crucial role in – or creating the required environment for – catalysis. Selenocysteine incorporation is DNA encoded, determined by the UGA codon, and occurs via a unique mechanism representing an expansion of the genetic code. Despite the conceptual conservation of the principal mechanism of selenocysteine synthesis and incorporation in all lines of descent, the bacterial system differs from the archaeal/eukaryal system. Detailed biochemical and structural knowledge of selenoprotein synthesis has allowed rewiring bacterial translation for targeted selenocysteine insertion.

Key Concepts

Selenium is an essential trace element for many organisms including humans.

The most important form of biologically active selenium is the amino acid selenocysteine.

Selenocysteine is co‐translationally inserted into growing polypeptides.

Selenocysteine insertion proceeds via a unique mechanism recoding UGA.

The mechanism of selenocysteine insertion differs in Bacteria, Archaea, and Eukarya.
Plant Virus Transmission by Insects
Authors: Fereres Alberto , Raccah Benjamin
Published: April 2015

Most plant viruses depend on insect vectors for their survival, transmission and spread. They transmit plant viruses by two principal modes, circulative (circulating through the insect's haemocoel, CV) and non‐circulative (carried on the cuticle lining of mouthparts or foregut, NC). Transmissibility and specificity between NC viruses and their vectors depends on the coat protein (CP) of the virus in addition to virus‐encoded helper proteins. Circulative viruses cross the gut, circulate in the haemocoel and cross the salivary glands to render the insect infective. Circulative luteoviruses depend on small CP and the read‐through protein (RTD) for transmission. Electrical penetration graphs have provided evidence on insect feeding behaviour and virus transmission. Recently, studies have shown that viruses can modify vector behaviour in a way that transmission is enhanced. Cultural, physical and novel biotechnological tools can provide virus control by interfering with vector landing and the retention of viruses in their vectors.

Key Concepts

Most plant viruses rely on insect vectors for survival, transmission and spread.

Aphids and whiteflies are by far the most important insects transmitting plant viruses.

Some plant viruses are associated to the cuticle of the insect mouthparts (non‐circulative), whereas others are retained in the salivary glands after they circulate through the insect's body (circulative).

Some non‐circulative viruses are retained in the common duct of the aphid's maxillary stylets and are inoculated by salivation during brief superficial intracellular probes.

Circulative viruses are inoculated during salivation stylet activities in phloem sieve elements.

Recent findings in the nature of insect proteins involved in the retention of virus or virus‐encoded helper proteins will help to develop new molecules to interfere with the transmission process.
NMR
Spectroscopy for Monitoring Functional Dynamics in Solution
Authors: Sivanandam VN , Millet Oscar
Published: April 2015

Protein functional dynamics are defined as the atomic thermal fluctuations or the segmental motions that are essential for the function of a biomolecule. NMR is a very versatile technique that is well suited for obtaining quantitative information from these processes at atomic resolution and in multiple timescales. This article focuses on recent NMR developments to study functional dynamics, making special incidence in the experiments aimed for the characterisation of chemical–conformational exchange in the microsecond to millisecond timescale. In a second section, the novel‐solution NMR techniques that combine chemical exchange with saturation transfer experiments are addressed to finish with an overview on the dynamic information that can be extracted from residual dipolar couplings.

Key Concepts

NMR is well suited to study biomolecular dynamics at multiple timescales.

Many enzymatic reactions occur in the microsecond to millisecond timescale.

Relaxation dispersion experiments can extract quantitative information about the exchange process.

CEST and DEST experiments provide useful information on conformations that are invisible in the NMR spectrum.

Residual dipolar couplings contain information about spin dynamics that can be extracted and quantified.
The Status of Women in the Life Sciences
Authors: Peters Jan W , Lane Nancy J
Published: April 2015

Women in the life sciences seem to attract less concern and attention than women in physics, IT or engineering. Perhaps because women in the life sciences at undergraduate and, more recently, postgraduate level have equalled or exceeded men for the past 30 or so years. The poor representation of women at professorial level in biology – still only 15% in the United Kingdom – shows an appalling waste of potential talent, often referred to as the ‘leaky pipeline’. Given the significant attention paid to the under‐representation of women across STEM (science, technology, engineering and maths) subjects globally by national academies, employers and governments over the past 15 years, it is disappointing to observe such poor progress.

More attention needs to be paid to the career planning and professional preparation of young women, so that more will be able to progress to senior positions and decision‐making roles. Educational institutions and employers need to evolve in the form of inclusive leadership, structural changes and good management policies and practices. Also, shifts from a purely male orientation of science and changes in cultural stances need to be implemented, including addressing unconscious bias by both women and men towards women and the recognition of the importance of diversity and inclusion.

Key Concepts

Women leave the life sciences at every step of the career ladder in greater proportions than men. This is termed the ‘leaky pipeline’.

Unconscious bias and discrimination against women, preventing their career advancement, results in fewer women in senior positions.

Much of scientific research is undertaken with little thought about whether there is a gender context; for example, omitting women from studies and trials.

There is a lack of career planning, personal development and preparation for leadership for women in the life sciences.

Creating a level playing field for women in life science requires the effective implementation of policies around recruitment, promotion and workplace cultures.
K
eilin,
D
avid
Authors: Prebble John N
Published: April 2015

David Keilin (1887–1963) was born in Moscow and grew up in Poland. At an early age, he moved via Liège to Paris where he acquired a reputation as a parasitologist. In 1914, he moved to Cambridge where he remained for the rest of his life and became the Director of the Molteno Institute. Here, he rediscovered the cytochromes, previously observed by MacMunn whose work was ignored, and went on to describe the respiratory chain. For a while his work brought him into conflict with Otto Warburg over the latter's respiratory enzyme, which Keilin eventually showed was the same as his cytochrome oxidase.
M
asatoshi
N
ei
Authors: Pievani Telmo
Published: April 2015

Evolutionary biology must recognise Masatoshi Nei's merit for three outstanding contributions: (1) an advancement in the scientific status of the discipline, which has been made by ‘molecular evolutionary biology’ more quantitative through a set of statistical methods for studying genetic diversity, changes in DNA, neutral evolution and molecular phylogenies; (2) the application of Nei's evolutionary genetic distance to the phylogenetic tree of human populations, supporting the out of Africa model of global dispersal, and (3) the overall recognition of the central role of mutations in evolution and the idea that the changes in DNA are not just ‘raw material’ for the natural selection but the main sources of innovation. Nei's alternative theory of evolution, intended as a process driven by mutation, seems biased by a narrow focus on molecular determination and tends to underestimate the large
corpus
of interdisciplinary evidence supporting the causal role of selective processes in evolution.
Protein Folding and Chaperones
Authors: Sinnige Tessa , Karagöz G Elif , Rüdiger Stefan GD
Published: April 2015

Proteins fold via specific pathways to achieve their native structure. Protein structures are, however, inherently unstable, hence folding and unfolding are in equilibrium. Protein instability is a major concern inside the cell. Specialised proteins called molecular chaperones are, therefore, required to assist proteins in folding and to prevent aggregation of folding intermediates. Many different classes of chaperones are conserved throughout all kingdoms of life, many of which are known as heat shock proteins. Chaperones typically recognise hydrophobic patches, but the exact functions and mechanisms of action of the various chaperone classes are very different. The main chaperone classes Hsp70, Hsp90, Hsp100 and chaperonins all depend on ATPase cycles, whose activities are fine‐tuned by co‐chaperones. The molecular understanding of the mechanism of both chaperones and protein folding are key problems in present‐day life sciences and molecular medicine.

Key Concepts

Proteins fold via pathways.

Protein structures are labile.

Protein folding
in vivo
is assisted by molecular chaperones.

Assisted protein folding requires ATP energy.

Molecular chaperones are evolutionary conserved.

Chaperone activity is controlled by co‐chaperones and co‐factors.

Chaperone families differ in structure and function.
Tuberculosis: Immunity
Authors: Orme Ian M
Published: April 2015

For centuries, tuberculosis has been recognised as one of the most dangerous diseases on the planet, and in the twenty‐first century, this situation has not changed. In fact, both in the context of prevention by vaccination and treatment by chemotherapy, it has proven very difficult to halt the continued global epidemic of this deadly disease – a situation further compounded by the concomitant HIV epidemic. The immune response to tuberculosis involves both innate and acquired immune responses. Should an infection established an integrated response involving antigen‐specific T lymphocytes and macrophages ensues (‘TH1 response’) that involves the formation of a cellular barrier (‘granuloma’) that is controlled by cytokines and chemokines. As the infection becomes contained, the effector immune response contracts and is gradually replaced by T cells capable of an accelerated memory response to further exposure.

Key Concepts

Immunity to tuberculosis is cell mediated.

The central even involves the interaction between antigen‐specific T cells and infected macrophages.

The response is complex and involves multiple soluble mediators including cytokines and chemokines.

The primary containment device involves the formation of a structure called the granuloma.

Contraction of effector immunity is followed by the emergence of still poorly understood memory immunity.
Genome Evolution in Yeasts
Authors: Dujon Bernard
Published: April 2015

Used empirically over millennia for a variety of fermentation processes, the microscopic yeasts representing unicellular forms of modern fungi adapted to a large diversity of habitats have become powerful model organisms to understand eukaryotic genome evolution. Their broad evolutionary range offers unique views on both short‐ and long‐term genomic changes, with the possibility to confront observations with experimental results. Processes of duplications, gene loss and
de novo
gene creation form the bases of genome evolution, along with horizontal acquisitions and an unexpectedly high frequency of interspecies hybridisations. This short review summarises our present knowledge about genome evolution focussing on the subphylum of budding yeasts or
Saccharomycotina
, by far the most extensively studied lineage, without ignoring the multiphyletic origin of yeasts.

Key Concepts

Yeasts represent long‐evolved unicellular forms of modern fungi, adapted to rapid clonal expansions under favourable conditions, not primitive eukaryotes.

Over 1600 yeast species are presently described in the different subphyla of
Ascomycota
and
Basidiomycota
, within which the budding yeasts (
Saccharomycotina)
represent the largest deep‐branching lineage useful for genome evolution studies.

The different genome architectures of well‐circumscribed subgroups of
Saccharomycotina
indicate major evolutionary divides within which ancient events can be inferred.

Important modifications of the role of RNA occurred at the origin of
Saccharomycotina
(massive loss of spliceosomal introns and loss of RNAi control) and continued during their evolution (fixation of 5S RNA gene, change of deciphering mode and significance for synonymous codons).

All yeast genomes exhibit significant levels of redundancy, reflecting small‐scale duplications and, in one lineage, a whole‐genome duplication followed by extensive gene loss.

The balance between gene gains and losses accelerated yeast genome evolution beyond sequence divergence and chromosomal dynamics.

Novel genes regularly appeared during yeast genome evolution, resulting from duplication followed by sequence divergence, horizontal acquisition and
de novo
gene creation.

Interspecies hybridisation is a common phenomenon.

Resolution of hybrid genomes suggests an important role for interspecific exchanges in evolution.
Methodologies for Phylogenetic Inference
Authors: Gil Manuel , Anisimova Maria
Published: April 2015

Phylogenetic inference from homologous molecular sequences is key to hypothesis testing and problem solving not only in evolutionary biology but also in a wide variety of other fields – from medicine to ecology. Model‐based phylogenetic methods rely on Markov substitution models to describe the molecular evolution as a stochastic process of character substitution over time on a phylogenetic tree relating the sequences. Model parameters are estimated with standard statistical inference methods, namely, Bayesian and maximum likelihood approaches. A typical phylogenetic analysis first infers a multiple sequence alignment. Given this alignment, a phylogenetic tree is then estimated together with branch lengths and model parameters. Ideally, the alignment and phylogeny should be estimated simultaneously, amongst others to take alignment uncertainty into account.

Key Concepts

Sequence Alignmentestimates an assignment of homologous molecular characters, that is, nucleotides, amino acids or codons related by common ancestry.

Phylogenetic Treeis the hierarchical representation of evolutionary relationships between homologous molecular sequences. The leaves of the tree usually represent the present day sequences, while the internal nodes represent the common ancestors.

Model of Molecular Evolutionis the mathematical description of the process of sequence change through time, such as character substitutions, insertions and deletions.

Phylogenetic Likelihoodis the probability function of observing the sequence data given the model of molecular evolution and phylogenetic tree.

Frequentist Phylogenetic Inferencerelies on optimised phylogenetic likelihood to estimate parameters of a model of molecular evolution and a phylogenetic tree.

Bayesian Phylogenetic Inferencerelies on phylogenetic likelihood and a prior probability distribution of parameters to obtain a posterior probability distribution of parameters of a model of molecular evolution and a phylogenetic tree.

Branch Supportquantifies the uncertainty of phylogenetic inference by assigning statistical confidence to the inferred partitions (i.e. clades) on a phylogenetic tree.

Alignment Uncertaintyquantifies the statistical confidence of sequence alignment, which compounds the uncertainty of phylogenetic inference.
Nuclear Membranes
Authors: Zuela Noam , Gruenbaum Yosef
Published: April 2015

The nuclear envelope (NE) is a double membrane barrier that separates the nuclear content from the cytoplasm. The outer nuclear membrane is contiguous with the endoplasmic reticulum (ER). The perinuclear space or lumen separates the nuclear membranes. Both nuclear membranes contain numerous nuclear envelope transmembrane proteins (NETs), many of them are expressed in a tissue‐ and developmental‐specific manner. These proteins are responsible for the majority of the recently discovered NE functions, which include cell migration, chromatin organisation, cell signalling, gene silencing and transcriptional regulation. NETs are also implicated in diseases, collectively known as nuclear envelopathies, affecting bones, skin, muscles, neurons and systemic disorders. The mechanisms leading to these diseases are largely unknown and are major research goals for future studies. Further studies of the nuclear membranes, their proteins and novel functions will help us expand our understanding of their vast array of cellular functions and gain insights into numerous diseases.

Key Concepts

The nuclear envelope separates the nucleus from the cytoplasm.

It is composed of an outer nuclear membrane (ONM), an inner nuclear membrane (INM), nuclear pore complexes (NPCs) and nuclear lamina.

The INM is fused to the ONM at the NPC sites.

The INM contains a unique set of nuclear envelope transmembrane proteins (NETs), many of which are expressed in a tissue‐specific manner.

Many NETs share common protein domains with other NETs including the LEM, SUN and KASH domains.

NETs are involved in regulating signalling pathways and gene positioning.

Most NETs interact either directly or indirectly with nuclear lamins.

SUN‐domain proteins interact in the perinuclear space with KASH‐domain proteins to make the LINC (linker of nucleoplasm and cytoplasm) complexes that physically link the nuclear interior with the cytoplasmic filament networks and organelles.

Mutations in several human NETs cause heritable diseases.
One‐Step Self‐Assembly Fabrication of High Quality NixMg1‐xO Bowl‐Shaped Array Film and Its Enhanced Photocurrent by Mg,2+ Doping
Authors: Zhao Yan , Hu Linfeng , Gao Shangpeng , Liao Meiyong , Sang Liwen , Wu Limin
Published: April 2015

A series of high quality NixMg1‐xO bowl‐shaped array films are successfully prepared by a simple one‐step assembly of polystyrene colloidal spheres and metal oxide precursors at oil–water interface, and further used to fabricate nanodevices. The doping of Mg2+ can greatly enhance the current and spectrum responsivity of NiO film‐based nanodevice. The maximum Rλ value of these bowl‐shaped NixMg1‐xO film‐based devices measured in the study shows 4–5 orders of enhancement than the previously reported NixMg1‐xO film at equal doping.
In Situ X‐Ray Diffraction Studies on Structural Changes of a P2 Layered Material during Electrochemical Desodiation/Sodiation
Authors: Jung Young Hwa , Christiansen Ane S. , Johnsen Rune E. , Norby Poul , Kim Do Kyung
Published: April 2015

Sodium layered oxides with mixed transition metals have received significant attention as positive electrode candidates for sodium‐ion batteries because of their high reversible capacity. The phase transformations of layered compounds during electrochemical reactions are a pivotal feature for understanding the relationship between layered structures and electrochemical properties. A combination of in situ diffraction and ex situ X‐ray absorption spectroscopy reveals the phase transition mechanism for the ternary transition metal system (Fe–Mn–Co) with P2 stacking. In situ synchrotron X‐ray diffraction using a capillary‐based microbattery cell shows a structural change from P2 to O2 in P2–Na0.7Fe0.4Mn0.4Co0.2O2 at the voltage plateau above 4.1 V on desodiation. The P2 structure is restored upon subsequent sodiation. The lattice parameter c in the O2 structure decreases significantly, resulting in a volumetric contraction of the lattice toward a fully charged state. Observations on the redox behavior of each transition metal in P2–Na0.7Fe0.4Mn0.4Co0.2O2 using X‐ray absorption spectroscopy indicate that all transition metals are involved in the reduction/oxidation process.
Flexible, Highly Graphitized Carbon Aerogels Based on Bacterial Cellulose/Lignin: Catalyst‐Free Synthesis and its Application in Energy Storage Devices
Authors: Xu Xuezhu , Zhou Jian , Nagaraju D. H. , Jiang Long , Marinov Val R. , Lubineau Gilles , Alshareef Husam N. , Oh Myungkeun
Published: April 2015

Currently, most carbon aerogels are based on carbon nanotubes (CNTs) or graphene, which are produced through a catalyst‐assisted chemical vapor deposition method. Biomass based organic aerogels and carbon aerogels, featuring low cost, high scalability, and small environmental footprint, represent an important new research direction in (carbon) aerogel development. Cellulose and lignin are the two most abundant natural polymers in the world, and the aerogels based on them are very promising. Classic silicon aerogels and available organic resorcinol–formaldehyde (RF) or lignin–resorcinol–formaldehyde (LRF) aerogels are brittle and fragile; toughening of the aerogels is highly desired to expand their applications. This study reports the first attempt to toughen the intrinsically brittle LRF aerogel and carbon aerogel using bacterial cellulose. The facile process is catalyst‐free and cost‐effective. The toughened carbon aerogels, consisting of blackberry‐like, core–shell structured, and highly graphitized carbon nanofibers, are able to undergo at least 20% reversible compressive deformation. Due to their unique nanostructure and large mesopore population, the carbon materials exhibit an areal capacitance higher than most of the reported values in the literature. This property makes them suitable candidates for flexible solid‐state energy storage devices. Besides energy storage, the conductive interconnected nanoporous structure can also find applications in oil/water separation, catalyst supports, sensors, and so forth.
Integrative Self‐Assembly of Graphene Quantum Dots and Biopolymers into a Versatile Biosensing Toolkit
Authors: Lin Yiyang , Chapman Robert , Stevens Molly M.
Published: April 2015

Hybrid self‐assembly has become a reliable approach to synthesize soft materials with multiple levels of structural complexity and synergistic functionality. In this work, photoluminescent graphene quantum dots (GQDs, 2–5 nm) are used for the first time as molecule‐like building blocks to construct self‐assembled hybrid materials for label‐free biosensors. Ionic self‐assembly of disc‐shaped GQDs and charged biopolymers is found to generate a series of hierarchical structures that exhibit aggregation‐induced fluorescence quenching of the GQDs and change the protein/polypeptide secondary structure. The integration of GQDs and biopolymers via self‐assembly offers a flexible toolkit for the design of label‐free biosensors in which the GQDs serve as a fluorescent probe and the biopolymers provide biological function. The versatility of this approach is demonstrated in the detection of glycosaminoglycans (GAGs), pH, and proteases using three strategies: 1) competitive binding of GAGs to biopolymers, 2) pH‐responsive structural changes of polypeptides, and 3) enzymatic hydrolysis of the protein backbone, respectively. It is anticipated that the integrative self‐assembly of biomolecules and GQDs will open up new avenues for the design of multifunctional biomaterials with combined optoelectronic properties and biological applications.
A New Approach for Fabricating Collagen/ECM‐Based Bioinks Using Preosteoblasts and Human Adipose Stem Cells
Authors: Lee Hyeong Jin , Kim Yong Bok , Ahn Seung Hyun , Lee Ji‐Seon , Jang Chul Ho , Yoon Hyeon , Chun Wook , Kim Geun Hyung
Published: April 2015

Cell‐printing methods have been used widely in tissue regeneration because they enable fabricating biomimetic 3D structures laden with various cells. To achieve a cell‐matrix block, various natural hydrogels that are nontoxic, biocompatible, and printable have been combined to obtain “bioinks.” Unfortunately, most bioinks, including those with alginates, show low cell‐activating properties. Here, a strategy for obtaining highly bioactive ink, which consisted of collagen/extracellular matrix (ECM) and alginate, for printing 3D porous cell blocks is developed. An in vitro assessment of the 3D porous structures laden with preosteoblasts and human adipose stem cells (hASCs) demonstrates that the cells in the bioinks are viable. Osteogenic activities with the designed bioinks show much higher levels than with the “conventional” alginate‐based bioink. Furthermore, the hepatogenic differentiation ability of hASCs with the bioink is evaluated using the liver‐specific genes, albumin, and TDO2, under hepatogenic differentiation conditions. The genes are activated within the 3D cell block fabricated using the new bioink. These results demonstrate that the 3D cell‐laden structure fabricated using collagen/ECM‐based bioinks can provide a novel platform for various tissue engineering applications.
Structural Revision and Elucidation of the Biosynthesis of Hypodoratoxide by 13C,13C COSY NMR Spectroscopy
Authors: Barra Lena , Ibrom Kerstin , Dickschat Jeroen S.
Published: April 2015

Feeding of (2,3,4,5,6‐13C5)mevalonolactone to the fungus Hypomyces odoratus resulted in a completely labeled sesquiterpene ether. The connectivity of the carbon atoms was easily deduced from a 13C,13C COSY spectrum, revealing a structure that was different from the previously reported structure of hypodoratoxide, even though the reported 13C NMR data matched. A structural revision of hypodoratoxide is thus presented. Its absolute configuration was tentatively assigned from its co‐metabolite cis‐dihydroagarofuran. Its biosynthesis was investigated by feeding of (3‐13C)‐ and (4,6‐13C2)mevalonolactone, which gave insights into the complex rearrangement of the carbon skeleton during terpene cyclization by analysis of the 13C,13C couplings.
Role of processing history on the mechanical and electrical behavior of melt‐compounded polycarbonate‐multiwalled carbon nanotube nanocomposites
Authors: Choong Gabriel Yew Hong , Lew Chun Yee , De Focatiis Davide Stefano Antonio
Published: April 2015

This work investigates the effects of primary compounding temperature and secondary melt processes on the mechanical response and electrical resistivity of polycarbonate filled with 3 wt % multiwalled carbon nanotubes (CNT). Nanocomposites were melt compounded in an industrial setting at a range of temperatures, and subsequently either injection molded or compression molded to produce specimens for the measurement of electrical resistivity, surface hardness, and uniaxial tensile properties. Secondary melt processing was found to be the dominant process in determining the final properties. The effects observed have been attributed to structural arrangements of the CNT network as suggested by morphological evidence of optical microscopy and resistivity measurements. Properties were found to be relatively insensitive to compounding temperature. The measured elastic moduli were consistent with existing micromechanical models. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42277.
Economic Structure, Social Risks and the Challenges to Social Policy in Macau, China
Authors: Li Bingqin , Zeng Zhonglu
Published: April 2015

Welfare state is often perceived as a response to help people coping with shocks caused by economic down turn. However, as argued by Hamnett, welfare state can directly assist economic restructuring. Thus, social policies can be responses to unsatisfied social needs or be proactive measures to push for economic changes.

Macau is in a somewhat special position in that policy‐makers are aware that the economy has been excessively dependent on the gaming industry. The government prevent it from being hit by recess through economic restructuring.

In this paper, we examine the current social spending pattern and the nature of the social security system in Macau and establish that social policy in Macau is largely reactive. To achieve economic restructuring, there needs to be more proactive measures to facilitate human development and more stress on social investment.
The decision to submit to a journal: Another example of a valence‐consistent Shift?
Authors: Pepermans Guido , Rousseau Sandra
Published: April 2015

In this article we use a stated choice experiment to study researcher preferences in the information sciences and to investigate the relative importance of different journal characteristics in convincing potential authors to submit to a particular journal. The analysis distinguishes high quality from standard quality articles and focuses on the question whether communicating acceptance rates rather than rejection rates leads to other submission decisions. Our results show that a positive framing effect might be present when authors decide on submitting a high quality article. No evidence of a framing effect is found when authors consider a standard quality article. From a journal marketing perspective, this is important information for editors. Communicating acceptance rates rather than rejection rates might help to convince researchers to submit to their journal.
Topiramate: a review of analytical approaches for biological matrices
Authors: Pinto Eduardo Costa , Dolzan Maressa Danielli , Cabral Lucio Mendes , Armstrong Daniel W. , de Sousa Valéria Pereira
Published: April 2015

Topiramate is an anticonvulsant drug and it has been used worldwide for a wide range of applications. It is mainly indicated for the treatment of partial and generalized seizures, including Lennox Gastant Syndrome and generalized tonic–clonic seizures, and prophylactic treatment of migraine. Different analytical approaches by high‐performance liquid chromatography have been described to analyze topiramate because of its lack of chromophore groups, including derivatization with UV‐absorbing moieties, derivatization with fluorescent moieties, refractive index detection, conductivity detection, chemiluminescent nitrogen detection, evaporative light scattering detection and MS detection. In addition, some methods for determination of topiramate by capillary electrophoresis have been published as well as by gas chromatography. Thus, it is beneficial to evaluate and compare these papers before selecting the most suitable method/detector to analyze this drug. This systematic review provides a description of the main analytical methods available for the analysis of topiramate in biological matrices. Each of these methods is briefly discussed considering the detector used with HPLC. HPLC coupled with MS is the main technique used for topiramate analysis in biological matrices, mainly in the electrospray ionization‐negative mode. Copyright © 2015 John Wiley & Sons, Ltd.
Determination of trimethylamine‐N‐oxide in combination with l‐carnitine and γ‐butyrobetaine in human plasma by UPLC/MS/MS
Authors: Grinberga Solveiga , Dambrova Maija , Latkovskis Gustavs , Strele Ieva , Konrade Ilze , Hartmane Dace , Sevostjanovs Eduards , Liepinsh Edgars , Pugovics Osvalds
Published: April 2015

An ultra‐high‐performance liquid chromatography–mass spectrometry (UPLC/MS/MS) method was developed and validated for the quantification of trimethylamine‐N‐oxide (TMAO) simultaneously with TMAO‐related molecules l‐carnitine and γ‐butyrobetaine (GBB) in human blood plasma. The separation of analytes was achieved using a Hydrophilic interaction liquid chromatography (HILIC)‐type column with ammonium acetate–acetonitrile as the mobile phase. TMAO determination was validated according to valid US Food and Drug Administration guidelines. The developed method was successfully applied to plasma samples from healthy volunteers. Copyright © 2015 John Wiley & Sons, Ltd.
Tungsten Carbide and CNT–Graphene‐Supported Pd Electrocatalyst toward Electrooxidation of Hydrogen
Authors: Han Suenghoon , Youn Duck Hyun , Lee Min Hee , Lee Jae Sung
Published: April 2015

Development of platinum‐free catalysts is urgently needed to make fuel cells a competitive technology for power generation in various fields. Here we report that combination of palladium and tungsten carbides supported on carbon nanotubes (CNT) graphene (GR) composite exhibits high activity for electrochemical hydrogen oxidation reaction. In the cyclic voltammetry, the electrochemical active surface area of Pd/WC/CNT–GR is much larger than that of other synthesized catalysts and even commercial Pt/C catalyst. In single cell operation, Pd/WC/CNT–GR shows 65 % of the maximum power density of the state‐of‐the‐art Pt/C catalyst and loses only 5 % of maximum power density after 50 h. Beneficial roles of WC and CNT–GR are discussed for the improved performance of palladium catalysts.
Off‐Stoichiometry in Alluaudite‐Type Sodium Iron Sulfate Na2+2xFe2−x(SO4)3 as an Advanced Sodium Battery Cathode Material
Authors: Oyama Gosuke , Nishimura Shin‐ichi , Suzuki Yuya , Okubo Masashi , Yamada Atsuo
Published: April 2015

An alluaudite‐type sodium iron sulfate has recently been discovered as a 3.8 V cathode material for low‐cost, high‐power, and efficient sodium‐ion batteries. To optimize the composition of the alluaudite phase and to explore further compounds, we have carefully surveyed the Na2SO4‐FeSO4 binary system. Solid‐state reactions at a moderate temperature of 623 K produce two stable phases: 1) vanthoffite‐structured Na6Fe(SO4)4 and 2) alluaudite‐type Na2+2xFe2−x(SO4)3 with a certain non‐stoichiometry. The possible compositional and structural flexibilities demonstrated in this work inspire further improvement of the alluaudite‐type sodium metal sulfates for advanced sodium‐ion batteries.
Hydroboration of Graphene Oxide: Towards Stoichiometric Graphol and Hydroxygraphane
Authors: Poh Hwee Ling , Sofer Zdeněk , Šimek Petr , Tomandl Ivo , Pumera Martin
Published: April 2015

Covalently functionalized graphene materials with well‐defined stoichiometric composition are of a very high importance in the research of 2D carbon material family due to their well‐defined properties. Unfortunately, most of the contemporary graphene‐functionalized materials do not have this kind of defined composition and, usually, the amount of heteroatoms bonded to graphene framework is in the range of 1–10 at. %. Herein, we show that by a well‐established hydroboration reaction chain, which introduces BH2 groups into the graphene oxide structure, followed by H2O2 or CF3COOH treatment as source of OH or H, we can obtain highly hydroxylated compounds of precisely defined composition with a general formula (C1O0.78H0.75)n, which we named graphol and highly hydroxylated graphane (C1(OH)0.51H0.14)n, respectively. These highly functionalized materials with an accurately defined composition are highly important for the field of graphene derivatives. The enhanced electrochemical performance towards important biomarkers as well as hydrogen evolution reaction is demonstrated.
Creating Coordination‐Based Cavities in a Multiresponsive Supramolecular Gel
Authors: Wei Shi‐Chao , Pan Mei , Fan Yuan‐Zhong , Liu Haoliang , Zhang Jianyong , Su Cheng‐Yong
Published: April 2015

Creating cavities in varying levels, from molecular containers to macroscopic materials of porosity, have long been motivated for biomimetic or practical applications. Herein, we report an assembly approach to multiresponsive supramolecular gels by integrating photochromic metal–organic cages as predefined building units into the supramolecular gel skeleton, providing a new approach to create cavities in gels. Formation of discrete O‐Pd2L4 cages is driven by coordination between Pd2+ and a photochromic dithienylethene bispyridine ligand (O‐PyFDTE). In the presence of suitable solvents (DMSO or MeCN/DMSO), the O‐Pd2L4 cage molecules aggregate to form nanoparticles, which are further interconnected through supramolecular interactions to form a three‐dimensional (3D) gel matrix to trap a large amount of solvent molecules. Light‐induced phase and structural transformations readily occur owing to the reversible photochromic open‐ring/closed‐ring isomeric conversion of the cage units upon UV/visible light radiation. Furthermore, such Pd2L4 cage‐based gels show multiple reversible gel–solution transitions when thermal‐, photo‐, or mechanical stimuli are applied. Such supramolecular gels consisting of porous molecules may be developed as a new type of porous materials with different features from porous solids.
Langmuir and Langmuir–Blodgett Films from Amphiphilic Pillar[5]arene‐Containing [2]Rotaxanes
Authors: Trinh Thi Minh Nguyet , Nierengarten Iwona , Holler Michel , Gallani Jean‐Louis , Nierengarten Jean‐François
Published: April 2015

Amphiphilic pillar[5]arene‐containing [2]rotaxanes have been prepared and fully characterized. In the particular case of the [2]rotaxane incorporating a 1,4‐diethoxypillar[5]arene subunit, the structure of the compound was confirmed by X‐ray crystal structure analysis. Owing to a good hydrophilic/hydrophobic balance, stable Langmuir films have been obtained for these rotaxanes and the size of the peripheral alkyl chains on the pillar[5]arene subunit has a dramatic influence on the reversibility during compression–decompression cycles. Indeed, when these are small enough, molecular reorganization of the rotaxane by gliding motions are capable of preventing strong π–π interactions between neighboring macrocycles in the thin film.
Bioresponsive probes for molecular imaging: concepts and in vivo applications
Authors: van Duijnhoven Sander M. J. , Robillard Marc S. , Langereis Sander , Grüll Holger
Published: April 2015

Molecular imaging is a powerful tool to visualize and characterize biological processes at the cellular and molecular level in vivo. In most molecular imaging approaches, probes are used to bind to disease‐specific biomarkers highlighting disease target sites. In recent years, a new subset of molecular imaging probes, known as bioresponsive molecular probes, has been developed. These probes generally benefit from signal enhancement at the site of interaction with its target. There are mainly two classes of bioresponsive imaging probes. The first class consists of probes that show direct activation of the imaging label (from “off” to “on” state) and have been applied in optical imaging and magnetic resonance imaging (MRI). The other class consists of probes that show specific retention of the imaging label at the site of target interaction and these probes have found application in all different imaging modalities, including photoacoustic imaging and nuclear imaging. In this review, we present a comprehensive overview of bioresponsive imaging probes in order to discuss the various molecular imaging strategies. The focus of the present article is the rationale behind the design of bioresponsive molecular imaging probes and their potential in vivo application for the detection of endogenous molecular targets in pathologies such as cancer and cardiovascular disease. Copyright © 2015 John Wiley & Sons, Ltd.
Three‐dimensional contrasted visualization of pancreas in rats using clinical MRI and CT scanners
Authors: Yin Ting , Coudyzer Walter , Peeters Ronald , Liu Yewei , Cona Marlein Miranda , Feng Yuanbo , Xia Qian , Yu Jie , Jiang Yansheng , Dymarkowski Steven , Huang Gang , Chen Feng , Oyen Raymond , Ni Yicheng
Published: April 2015

The purpose of this work was to visualize the pancreas in post‐mortem rats with local contrast medium infusion by three‐dimensional (3D) magnetic resonance imaging (MRI) and computed tomography (CT) using clinical imagers. A total of 16 Sprague Dawley rats of about 300 g were used for the pancreas visualization. Following the baseline imaging, a mixed contrast medium dye called GadoIodo‐EB containing optimized concentrations of Gd‐DOTA, iomeprol and Evens blue was infused into the distally obstructed common bile duct (CBD) for post‐contrast imaging with 3.0 T MRI and 128‐slice CT scanners. Images were post‐processed with the MeVisLab software package. MRI findings were co‐registered with CT scans and validated with histomorphology, with relative contrast ratios quantified. Without contrast enhancement, the pancreas was indiscernible. After infusion of GadoIodo‐EB solution, only the pancreatic region became outstandingly visible, as shown by 3D rendering MRI and CT and proven by colored dissection and histological examinations. The measured volume of the pancreas averaged 1.12 ± 0.04 cm3 after standardization. Relative contrast ratios were 93.28 ± 34.61% and 26.45 ± 5.29% for MRI and CT respectively. We have developed a multifunctional contrast medium dye to help clearly visualize and delineate rat pancreas in situ using clinical MRI and CT scanners. The topographic landmarks thus created with 3D demonstration may help to provide guidelines for the next in vivo pancreatic MRI research in rodents. Copyright © 2015 John Wiley & Sons, Ltd.