bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural characterization and observation of variable range hopping conduction mechanism at high temperature in CdSe quantum dot solids
Authors: Sinha Subhojyoti , Kumar Chatterjee Sanat , Ghosh Jiten , Kumar Meikap Ajit
Published: March 2013

We have used Rietveld refinement technique to extract the microstructural parameters of thioglycolic acid capped CdSe quantum dots. The quantum dot formation and its efficient capping are further confirmed by HR-TEM, UV-visible and FT-IR spectroscopy. Comparative study of the variation of dc conductivity with temperature (298 K ≤ T ≤ 460 K) is given considering Arrhenius formalism, small polaron hopping and Schnakenberg model. We observe that only Schnakenberg model provides good fit to the non-linear region of the variation of dc conductivity with temperature. Experimental variation of ac conductivity and dielectric parameters with temperature (298 K ≤ T ≤ 460 K) and frequency (80 Hz ≤ f ≤ 2 MHz) are discussed in the light of hopping theory and quantum confinement effect. We have elucidated the observed non-linearity in the I-V curves (measured within ±50 V), at dark and at ambient light, in view of tunneling mechanism. Tunnel exponents and non-linearity weight factors have also been evaluated in this regard.
Dewetting of Au and AuPt alloy films: A dewetting zone model
Authors: Manuela Müller Claudia , Spolenak Ralph
Published: March 2013

When thin metal films are annealed they can degrade into particles. This happens even at annealing temperatures below the melting point and is known as solid-state dewetting or agglomeration. The solid-state dewetting behaviour of 15–35 nm thick Au and 20 nm thick AuPt films on SiNx/SiO2/Si substrates was investigated in the temperature range of 500–900 °C in air. Morphology maps were created based on which a dewetting zone model is proposed. The morphology maps can be divided into three zones: a zone where the film remains continuous, a zone where dewetting takes place, and a zone where dewetting is complete. Coverage measurements can be used to determine zone boundaries and the activation energy for void growth, which was 1.05 ± 0.1 eV in the case of Au. The influence of film thickness and alloying on the dewetting behaviour was studied; both factors had only an influence at low annealing temperatures, with the influence of alloying being more pronounced than the influence of film thickness.
Modulation bandwidth studies of recombination processes in blue and green InGaN quantum well micro-light-emitting diodes
Authors: Green Richard P. , McKendry Jonathan J. D. , Massoubre David , Gu Erdan , Dawson Martin D. , Kelly A. E.
Published: March 2013

We report modulation bandwidth measurements on a number of InGaN-based quantum well LEDs emitting at 450 and 520 nm wavelengths. It is shown that for these devices the data can be interpreted in terms of Auger recombination, by taking account of the carrier density dependence of the radiative coefficient. We find values for the Auger coefficient of (1±0.3)×10−29cm6s−1 at 450 nm and (3±1)×10−30cm6s−1 at 520 nm.
Note: An environmental cell for transient spectroscopy on solid samples in controlled atmospheres
Authors: Dwyer Jason R. , Szyc Łukasz , Nibbering Erik T. J. , Elsaesser Thomas
Published: March 2013

A sample cell for performing time-resolved spectroscopy on solid samples within an atmosphere of controlled vapor composition was designed and constructed. Control over vapor composition was accomplished using a combination of passive sealing and chemical agents. Performance characteristics especially well-suited to studies using femtosecond mid-infrared spectroscopy were achieved by the use of ultrathin silicon nitride windows and a rapid and reproducible sample cell exchange mechanism.
Enhanced controllability of domain-wall pinning by selective domain-wall injection
Authors: Ahn Sung-Min
Published: March 2013

It is experimentally reported that depinning fields of domain walls (DWs) under an interaction between magnetic charges distributed at a nanobar and at a notch can be enhanced by controlling injection fields for injecting DWs into the ferromagnetic nanowire with an asymmetrical nucleation pad. The DWs injected from the asymmetrical pad show an asymmetrical dependence of the injection field on the saturation angle and are pinned by the notch with the nanobar vertical to it. We have found that the shape of the pinning potential energy experienced by the DW is affected by the uniformly magnetized direction of the nanobar and the pinning potential energy is locally modified by selectively controlling the DW-injection. This is consistent with our estimation based on micromagnetic simulation.
Elastic superlattices with simultaneously negative effective mass density and shear modulus
Authors: Solís-Mora I. S. , Palomino-Ovando M. A. , Pérez-Rodríguez F.
Published: March 2013

We investigate the vibrational properties of superlattices with layers of rubber and polyurethane foam, which can be either conventional or auxetic. Phononic dispersion calculations show a second pass band for transverse modes inside the lowest band gap of the longitudinal modes. In such a band, the superlattices behave as a double-negative elastic metamaterial since the effective dynamic mass density and shear modulus are both negative. The pass band is associated to a Fabry-Perot resonance band which turns out to be very narrow as a consequence of the high contrast between the acoustic impedances of the superlattice components.
Ion impact distribution over plasma exposed nanocone arrays
Authors: Mehrabian S. , Xu S. , Qaemi A. A. , Shokri B. , Ostrikov K.
Published: March 2013

The effect of an ordered array of nanocones on a conducting substrate immersed in the plasma on the transport of the plasma ions is investigated. The real conical shape of the cones is rigorously incorporated into the model. The movement of 105 CH3+ ions in the plasma sheath modified by the nanocone array is simulated. The ions are driven by the electric fields produced by the sheath and the nanostructures. The surface charge density and the total charge on the nanotips with different aspect ratios are computed. The ion transport simulation provides important characteristics of the displacement and velocity of the ions. The relative ion distribution along the lateral surfaces of the carbon nanotips is computed as well. It is shown that a rigorous account of the realistic nanostructure shape leads to very different distribution of the ion fluxes on the nanostructured surfaces compared to the previously reported works. The ion flux distribution is a critical factor in the nucleation process on the substrate and determines the nanostructure growth patterns.
Atmospheric pressure resistive barrier air plasma jet induced bacterial inactivation in aqueous environment
Authors: Thiyagarajan Magesh , Sarani Abdollah , Gonzales Xavier
Published: March 2013

An atmospheric pressure resistive barrier air plasma jet is designed to inactivate bacteria in aqueous media in direct and indirect exposure modes of treatment. The resistive barrier plasma jet is designed to operate at both dc and standard 50–60 Hz low frequency ac power input and the ambient air at 50% humidity level was used as the operating gas. The voltage-current characteristics of the plasma jet were analyzed and the operating frequency of the discharge was measured to be 20 kHz and the plasma power was measured to be 26 W. The plasma jet rotational temperatures (Trot) are obtained from the optical emission spectra, from the N2C-B(2+) transitions by matching the experimental spectrum results with the Spectra Air (SPECAIR) simulation spectra. The reactive oxygen and nitrogen species were measured using optical emission spectroscopy and gas analyzers, for direct and indirect treatment modes. The nitric oxides (NO) were observed to be the predominant long lived reactive nitrogen species produced by the plasma. Three different bacteria including Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Neisseria meningitidis (Gram-negative) were suspended in an aqueous media and treated by the resistive barrier air plasma jet in direct and indirect exposure modes. The results show that a near complete bacterial inactivation was achieved within 120 s for both direct and indirect plasma treatment of S. aureus and E. coli bacteria. Conversely, a partial inactivation of N. meningitidis was observed by 120 s direct plasma exposure and insignificant inactivation was observed for the indirect plasma exposure treatment. Plasma induced shifts in N. meningitidis gene expression was analyzed using pilC gene expression as a representative gene and the results showed a reduction in the expression of the pilC gene compared to untreated samples suggesting that the observed protection against NO may be regulated by other genes.
Near-field light concentration of ultra-small metallic nanoparticles for absorption enhancement in a-Si solar cells
Authors: Cai Boyuan , Jia Baohua , Shi Zhengrong , Gu Min
Published: March 2013

Near-field light concentration from plasmonic nanostructures was predicted to significantly improve solar cell conversion efficiency since the inception of plasmonic solar cells. However the challenge remains in designing effective nanostructures for useful near-field enhancement much exceeding the detrimental ohmic loss and light blockage losses in solar cells. We propose and demonstrate ultra-small (a few nanometers) gold nanoparticles integrated in amorphous silicon solar cells between the front electrode and the photoactive layer. Significant enhancements in both the photocurrent (14.1%) and fill factor (12.3%) have been achieved due to the strong plasmonic near-field concentration and the reduced contact resistance, respectively.
Feasibility analysis and proof of concept for thermoelectric energy harvesting in mobile computers
Authors: Denker R. , Muhtaroğlu A.
Published: March 2013

Thermoelectric (TE) energy harvesting in compact microelectronic systems necessitates detailed upfront analysis to ensure unacceptable performance degradation is avoided. TE integration into a notebook computer is empirically investigated in this work for energy harvesting. A detailed finite element model was constructed first for thermal simulations. The model outputs were then correlated with the thermal validation results of the selected system. In parallel, a commercial TE micro-module was empirically characterized to quantify maximum power generation opportunity from the combined system and component data set. Next, suitable “warm spots” were identified within the mobile computer model to extract TE power with minimum or no notable impact to system performance, as measured by simulated thermal changes in the system. The prediction was validated by integrating a TE micro-module to the mobile system under test. Measured TE power generation density in the vicinity of the heat pipe was 1.26 mW/cm3 using high CPU load. The generated power scales down with lower CPU activity, and will scale up in proportion to the utilized opportunistic space within the system. The technical feasibility of TE energy harvesting in mobile computers has hence been experimentally proven for the first time.
Seasonal and stage of lactation effects on milk fat composition in northern Victoria
Authors: Walker G. P. , Wijesundera C. , Dunshea F. R. , Doyle P. T.
Published: March 2013

Effect of herd nutrition, time of year and season of calving on milk fat composition and physical properties were examined on irrigated commercial dairy farms in northern Victoria that made use of split-calving and a diverse range of feeding systems. Twenty-four farms were included in the study, and from each farm, morning and evening milk samples were collected from 16 cows that calved in autumn and 16 cows that calved in spring. There were no significant effects of season of calving on the concentration of fatty acids or phospholipids in milk fat, but there were interactions between season of calving and time of year (P < 0.001). These differences could be attributed to changes in energy balance and body condition with stage of lactation. The phospholipids comprising mainly phosphotidylcholine (PC), phosphtidylethanolamine (PE) and sphingomyelin (SP) also varied, with PC and PE being highest in late lactation and SP lowest during peak and mid lactation for both calving groups. Milk fat colour and the concentrations of free fatty acids were more influenced by factors associated with time of year rather than stage of lactation. Milk fat colour in particular showed strong seasonal variation being distinctly lighter in summer–early autumn when compared with rest of the year. Increasing the amount of concentrates fed was associated with decreases in short-chain fatty acid concentration and increases in the solid fat content of milk fat. Variations in nutritional management practices had only small (non-significant) effects on fat composition.
Changes in xylem tissue and laccase transcript abundance associated with posture recovery in Chamaecyparis obtusa saplings growing on an incline
Authors: Sato Saori , Hiraide Hideto , Yoshida Masato , Yamamoto Hiroyuki
Published: March 2013

Lignin is a major component of plant cell walls and is synthesised through oxidative polymerisation of monolignols. The transcription level of laccase, an enzyme implicated in monolignol polymerisation, is higher in the tissue forming compression wood than in normal wood. Compression wood, which is a special xylem tissue that develops to reorient inclined stems, also has a higher lignin content than normal wood. In the present study, Chamaecyparis obtusa Endl. saplings were grown on an incline and the following variables were tracked for 10 weeks: posture recovery of the saplings; development of xylem tissue on the lower side of inclined stems; and the transcription level of laccase. The posture of saplings approached vertical after 8 weeks, the development of compression wood reached a peak around 6 weeks and laccase transcription was the highest after 4 weeks. These results suggest a sequence of righting mechanisms. Inclination stimulates an increase in the abundance of laccase transcript and this increase encourages the formation of compression wood. The accumulation of compression wood then causes the stem to bend upward.
Topological defects and density fluctuations in collectively moving systems
Authors: Schaller Volker , Bausch Andreas R.
Published: March 2013

Ensembles of collectively moving particles like flocks of birds, bacteria, or filamentous polymers show a broad range of intriguing phenomena, yet seem to obey very similar physical principles. These generic principles have been predicted to lead to characteristic density fluctuations, which are in sharp contrast to normal fluctuations determining the properties of ordered systems in thermal equilibrium. Using high-density motility assays of driven filaments, we characterize here the origin and nature of giant fluctuations that emerge in this class of systems. By showing that these unique statistical properties result from the coupling between particle density and the topology of the velocity field of the particles, we provide insight in the physics of collective motion.
Evidence for a persistent microbial seed bank throughout the global ocean
Authors: Gibbons Sean M. , Caporaso J. Gregory , Pirrung Meg , Field Dawn , Knight Rob , Gilbert Jack A.
Published: March 2013

Do bacterial taxa demonstrate clear endemism, like macroorganisms, or can one site’s bacterial community recapture the total phylogenetic diversity of the world’s oceans? Here we compare a deep bacterial community characterization from one site in the English Channel (L4-DeepSeq) with 356 datasets from the International Census of Marine Microbes (ICoMM) taken from around the globe (ranging from marine pelagic and sediment samples to sponge-associated environments). At the L4-DeepSeq site, increasing sequencing depth uncovers greater phylogenetic overlap with the global ICoMM data. This site contained 31.7–66.2% of operational taxonomic units identified in a given ICoMM biome. Extrapolation of this overlap suggests that 1.93 × 10
11
sequences from the L4 site would capture all ICoMM bacterial phylogenetic diversity. Current technology trends suggest this limit may be attainable within 3 y. These results strongly suggest the marine biosphere maintains a previously undetected, persistent microbial seed bank.
ARID4A and ARID4B regulate male fertility, a functional link to the AR and RB pathways
Authors: Wu Ray-Chang , Jiang Ming , Beaudet Arthur L. , Wu Mei-Yi
Published: March 2013

ARID4A and ARID4B are homologous members of the
ARID
(AT-rich interaction domain) gene family. ARID4A and ARID4B physically interact with each other. ARID4A is a retinoblastoma (RB)-binding protein. Biological function of these interactions is still unknown. Here, we report that mice with complete deficiency of
Arid4a
, combined with haploinsufficiency of
Arid4b
(
Arid4a
−/−
Arid4b
+/−
), showed progressive loss of male fertility, accompanied by hypogonadism and seminal vesicle agenesis/hypodysplasia.
Arid4a
and
Arid4b
are expressed mainly in Sertoli cells of testes, which implies that their roles in Sertoli cell function are to support spermatogenesis and create the impermeable blood–testis barrier. In fact, evaluation of germ cell development in the
Arid4a
−/−
Arid4b
+/−
mice showed spermatogenic arrest at the stages of meiotic spermatocytes and postmeiotic haploid spermatids. Analysis of the integrity of the blood–testis barrier showed increased permeability of seminiferous tubules in the
Arid4a
−/−
Arid4b
+/−
testes. Interestingly, phenotypic Sertoli cell dysfunction in the
Arid4a
−/−
Arid4b
+/−
mice, including spermatogenic failures and the impaired blood–testis barrier, recapitulated the defects found in the Sertoli cell-specific androgen receptor (AR) knockout mice and the Sertoli cell-specific RB knockout mice. Investigation of the molecular mechanism identified several AR- and RB-responsive genes as downstream targets of ARID4A and ARID4B. Our results thus indicate that ARID4A and ARID4B function as transcriptional coactivators for AR and RB and play an integral part in the AR and RB regulatory pathways involved in the regulation of Sertoli cell function and male fertility.
Emergence of metachronal waves in cilia arrays
Authors: Elgeti Jens , Gompper Gerhard
Published: March 2013

Propulsion by cilia is a fascinating and universal mechanism in biological organisms to generate fluid motion on the cellular level. Cilia are hair-like organelles, which are found in many different tissues and many uni- and multicellular organisms. Assembled in large fields, cilia beat neither randomly nor completely synchronously—instead they display a striking self-organization in the form of metachronal waves (MCWs). It was speculated early on that hydrodynamic interactions provide the physical mechanism for the synchronization of cilia motion. Theory and simulations of physical model systems, ranging from arrays of highly simplified actuated particles to a few cilia or cilia chains, support this hypothesis. The main questions are how the individual cilia interact with the flow field generated by their neighbors and synchronize their beats for the metachronal wave to emerge and how the properties of the metachronal wave are determined by the geometrical arrangement of the cilia, like cilia spacing and beat direction. Here, we address these issues by large-scale computer simulations of a mesoscopic model of 2D cilia arrays in a 3D fluid medium. We show that hydrodynamic interactions are indeed sufficient to explain the self-organization of MCWs and study beat patterns, stability, energy expenditure, and transport properties. We find that the MCW can increase propulsion velocity more than 3-fold and efficiency almost 10-fold—compared with cilia all beating in phase. This can be a vital advantage for ciliated organisms and may be interesting to guide biological experiments as well as the design of efficient microfluidic devices and artificial microswimmers.
Retrograde monosynaptic tracing reveals the temporal evolution of inputs onto new neurons in the adult dentate gyrus and olfactory bulb
Authors: Deshpande Aditi , Bergami Matteo , Ghanem Alexander , Conzelmann Karl-Klaus , Lepier Alexandra , Götz Magdalena , Berninger Benedikt
Published: March 2013

Significance

New neurons are constantly added to the hippocampus and the olfactory bulb. These neurons are believed to fulfill unique functions during their early life compared with mature neurons, which may depend on the way they are connected. Here we studied the stepwise integration of new neurons within these two brain areas using a rabies-virus–based synaptic tracing tool. Our study revealed that in both areas integration follows a similar logic, with adult-born neurons incorporating first into the local circuit before becoming innervated by long-range connections. This changing pattern of presynaptic connectivity likely contributes to adult-born neurons’ functions.
Uranium redox transition pathways in acetate-amended sediments
Authors: Bargar John R. , Williams Kenneth H. , Campbell Kate M. , Long Philip E. , Stubbs Joanne E. , Suvorova ElenaI I. , Lezama-Pacheco Juan S. , Alessi Daniel S. , Stylo Malgorzata , Webb Samuel M. , Davis James A. , Giammar Daniel E. , Blue Lisa Y. , Bernier-Latmani Rizlan
Published: March 2013

Redox transitions of uranium [from U(VI) to U(IV)] in low-temperature sediments govern the mobility of uranium in the environment and the accumulation of uranium in ore bodies, and inform our understanding of Earth’s geochemical history. The molecular-scale mechanistic pathways of these transitions determine the U(IV) products formed, thus influencing uranium isotope fractionation, reoxidation, and transport in sediments. Studies that improve our understanding of these pathways have the potential to substantially advance process understanding across a number of earth sciences disciplines. Detailed mechanistic information regarding uranium redox transitions in field sediments is largely nonexistent, owing to the difficulty of directly observing molecular-scale processes in the subsurface and the compositional/physical complexity of subsurface systems. Here, we present results from an in situ study of uranium redox transitions occurring in aquifer sediments under sulfate-reducing conditions. Based on molecular-scale spectroscopic, pore-scale geochemical, and macroscale aqueous evidence, we propose a biotic–abiotic transition pathway in which biomass-hosted mackinawite (FeS) is an electron source to reduce U(VI) to U(IV), which subsequently reacts with biomass to produce monomeric U(IV) species. A species resembling nanoscale uraninite is also present, implying the operation of at least two redox transition pathways. The presence of multiple pathways in low-temperature sediments unifies apparently contrasting prior observations and helps to explain sustained uranium reduction under disparate biogeochemical conditions. These findings have direct implications for our understanding of uranium bioremediation, ore formation, and global geochemical processes.
Dimerization of complement factor H-related proteins modulates complement activation in vivo
Authors: Goicoechea de Jorge Elena , Caesar Joseph J. E. , Malik Talat H. , Patel Mitali , Colledge Matthew , Johnson Steven , Hakobyan Svetlana , Morgan B. Paul , Harris Claire L. , Pickering Matthew C. , Lea Susan M.
Published: March 2013

The complement system is a key component regulation influences susceptibility to age-related macular degeneration, meningitis, and kidney disease. Variation includes genomic rearrangements within the complement factor H-related (
CFHR
) locus. Elucidating the mechanism underlying these associations has been hindered by the lack of understanding of the biological role of CFHR proteins. Here we present unique structural data demonstrating that three of the CFHR proteins contain a shared dimerization motif and that this hitherto unrecognized structural property enables formation of both homodimers and heterodimers. Dimerization confers avidity for tissue-bound complement fragments and enables these proteins to efficiently compete with the physiological complement inhibitor, complement factor H (CFH), for ligand binding. Our data demonstrate that these CFHR proteins function as competitive antagonists of CFH to modulate complement activation in vivo and explain why variation in the CFHRs predisposes to disease.
Viscoelastic properties of the nematode
Caenorhabditis elegans
, a self-similar, shear-thinning worm
Authors: Backholm Matilda , Ryu William S. , Dalnoki-Veress Kari
Published: March 2013

Undulatory motion is common to many creatures across many scales, from sperm to snakes. These organisms must push off against their external environment, such as a viscous medium, grains of sand, or a high-friction surface; additionally they must work to bend their own body. A full understanding of undulatory motion, and locomotion in general, requires the characterization of the material properties of the animal itself. The material properties of the model organism
Caenorhabditis elegans
were studied with a micromechanical experiment used to carry out a three-point bending measurement of the worm. Worms at various developmental stages (including dauer) were measured and different positions along the worm were probed. From these experiments we calculated the viscoelastic properties of the worm, including the effective spring constant and damping coefficient of bending.
C. elegans
moves by propagating sinusoidal waves along its body. Whereas previous viscoelastic approaches to describe the undulatory motion have used a Kelvin–Voigt model, where the elastic and viscous components are connected in parallel, our measurements show that the Maxwell model, where the elastic and viscous components are in series, is more appropriate. The viscous component of the worm was shown to be consistent with a non-Newtonian, shear-thinning fluid. We find that as the worm matures it is well described as a self-similar elastic object with a shear-thinning damping term and a stiffness that becomes smaller as one approaches the tail.
Heparin-binding domain of fibrin(ogen) binds growth factors and promotes tissue repair when incorporated within a synthetic matrix
Authors: Martino Mikaël M. , Briquez Priscilla S. , Ranga Adrian , Lutolf Matthias P. , Hubbell Jeffrey A.
Published: March 2013

By binding growth factors (GFs), the ECM tightly regulates their activity. We recently reported that the heparin-binding domain II of fibronectin acts as a promiscuous high-affinity GF-binding domain. Here we hypothesized that fibrin, the provisional ECM during tissue repair, also could be highly promiscuous in its GF-binding capacity. Using multiple affinity-based assays, we found that fibrin(ogen) and its heparin-binding domain bind several GFs from the PDGF/VEGF and FGF families and some GFs from the TGF-β and neurotrophin families. Overall, we identified 15 unique binding interactions. The GF binding ability of fibrinogen caused prolonged retention of many of the identified GFs within fibrin. Thus, based on the promiscuous and high-affinity interactions in fibrin, GF binding may be one of fibrin’s main physiological functions, and these interactions may potentially play an important and ubiquitous role during tissue repair. To prove this role in a gain-of-function model, we incorporated the heparin-binding domain of fibrin into a synthetic fibrin-mimetic matrix. In vivo, the multifunctional synthetic matrix could fully mimic the effect of fibrin in a diabetic mouse model of impaired wound healing, demonstrating the benefits of generating a hybrid biomaterial consisting of a synthetic polymeric scaffold and recombinant bioactive ECM domains. The reproduction of GF–ECM interactions with a fibrin-mimetic matrix could be clinically useful, and has the significant benefit of a more straightforward regulatory path associated with chemical synthesis rather than human sourcing.
Efficient stochastic superparameterization for geophysical turbulence
Authors: Grooms Ian , Majda Andrew J.
Published: March 2013

Efficient computation of geophysical turbulence, such as occurs in the atmosphere and ocean, is a formidable challenge for the following reasons: the complex combination of waves, jets, and vortices; significant energetic backscatter from unresolved small scales to resolved large scales; a lack of dynamical scale separation between large and small scales; and small-scale instabilities, conditional on the large scales, which do not saturate. Nevertheless, efficient methods are needed to allow large ensemble simulations of sufficient size to provide meaningful quantifications of uncertainty in future predictions and past reanalyses through data assimilation and filtering. Here, a class of efficient stochastic superparameterization algorithms is introduced. In contrast to conventional superparameterization, the method here (
i
) does not require the simulation of nonlinear eddy dynamics on periodic embedded domains, (
ii
) includes a better representation of unresolved small-scale instabilities, and (
iii
) allows efficient representation of a much wider range of unresolved scales. The simplest algorithm implemented here radically improves efficiency by representing small-scale eddies at and below the limit of computational resolution by a suitable one-dimensional stochastic model of random-direction plane waves. In contrast to heterogeneous multiscale methods, the methods developed here do not require strong scale separation or conditional equilibration of local statistics. The simplest algorithm introduced here shows excellent performance on a difficult test suite of prototype problems for geophysical turbulence with waves, jets, and vortices, with a speedup of several orders of magnitude compared with direct simulation.
Metaphor in translation
Authors: Schäffner Christina , Shuttleworth Mark
Published: March 2013

This paper explores potential benefits of closer interaction between metaphor studies and translation process research. It presents some developments within translation studies that make use of conceptual metaphor theory and illustrates some process research methods for investigating metaphors. The paper considers a number of methodological recommendations and argues that the need to take full account of insights from metaphor studies and associated disciplines is of greatest importance. Another significant potential innovation is the use of a multilingual approach in respect of both product- and process-oriented studies in order to increase both the amount and the generality of data available for analysis. Thirdly, it is important to extend the current source-text (ST) oriented approach. The paper concludes by suggesting some options for triangulating data gathered through a combination of methods.
“All Rulers are Brothers”: Russian Relations with the Iranian Monarchy in the Nineteenth Century
Authors: Deutschmann Moritz
Published: March 2013

The article examines the history of the relationship between the Iranian and the Russian monarchies during the nineteenth and early twentieth century. Drawing on a broad range of hitherto unexplored sources in Russian, the article analyzes Russian attitudes towards the Qajars, for whom the Romanov tsars were at the same time the most important ally and the biggest threat. The article focuses on the symbols and ceremonies by which the monarchs represented their relations, and by which they expressed symbolic competition, recognition and domination. The article thus opens a new perspective on Russia's influence on the Qajars and also raises questions about the comparative history of both monarchies.
Optimal Effort Intensity in Backpack Electrofishing Surveys
Authors: Stanfield L. W. , Lester N. P. , Petreman I. C.
Published: March 2013

We evaluated the effect of backpack electrofishing effort intensity on the precision of estimates of fish density in a southern Ontario stream. Single-pass electrofishing was conducted on 30 sites at three electrofishing effort intensities (5, 10 and 15 s/m2). We found that an effort of 5 s/m2 yielded an average catch that was 78% of the 15-s/m2 effort. An asymptotic model effectively described the catch–effort relationship for most fish taxa in the stream (i.e., Rainbow Trout Oncorhynchus mykiss, Brown Trout Salmo trutta, sculpin Cottus sp., dace Rhinichthys sp., and darter Etheostoma sp.). Using the catchability parameters of this model, we evaluated the trade-off between sampling many sites at low intensity or fewer sites at higher intensity. The survey design that maximizes precision of fish-density estimates depends on the average time spent traveling between sites and the average area of sites. For southern Ontario streams, where sample sites were approximately 300 m2 and travel time between sites was 75 min, the optimum electrofishing effort intensity was approximately 5 s/m2. The applicability of these results to other systems was demonstrated by showing how this optimum intensity was affected by differences in catchability rates of fish and travel distances. These findings will be used to standardize single pass electrofishing catches in nonshield areas of Ontario, and the approach may prove useful in other areas where this fishing technique is effective.

Received January 5, 2012; accepted December 7, 2012
A Rich Vein? Novel Disseisin and the Trowell Coalmine Case of 1258
Authors: Goddard Richard , Musson Janice
Published: March 2013

This work presents a transcription and translation of a case of novel disseisin brought before the Nottingham assizes in 1257. Its importance lies in the fact that the case is concerned with a coalmine in Nottinghamshire. It offers important new evidence in three key areas: early, thirteenth-century enclosures, the earliest evidence for coal mining in the Nottinghamshire coalfield and very rare evidence of pit-head sales of coal. The accompanying commentary discusses these themes in detail in conjunction with the legal context of novel disseisin, the details of the case itself - with particular reference to the litigants themselves - and suggests that the numerous and early surviving novel disseisin cases may be an additional source of evidence for social historians in a period when other documentation might be lacking.
The influence of suspended nanoparticles on the Frederiks threshold of the nematic host
Authors: Klein Susanne , Richardson Robert M. , Greasty Robert , Jenkins Rhys , Stone Joseph , Thomas Michael R. , Sarua Andrei
Published: March 2013

In recent years, several papers reported an enhanced dielectric anisotropy when ferroelectric particles were suspended in a liquid crystal. These results seem to be sensitive to the liquid crystal used and the preparation method of the ferroelectric particles. In this paper, we compare different preparation methods of suspended barium titanate in two different liquid crystal hosts. As a control experiment, we followed similar preparation steps with non-ferroelectric silica particles. In all cases, we found a broadening of the optical Frederiks transition but no change in the dielectric anisotropy. Raman spectroscopy has been used to investigate the loss of tetragonal structure in the barium titanate as a function of milling time and particle size. As reported in the earlier literature, barium titanate does not exhibit a well-defined tetragonal crystal structure below a certain particle size and loses its ferroelectric features. This provides a simple rationalization for the absence of any dielectric enhancement.
Bulk fluid phase behaviour of colloidal platelet–sphere and platelet–polymer mixtures
Authors: de las Heras Daniel , Schmidt Matthias
Published: March 2013

Using a geometry-based fundamental measure density functional theory, we calculate bulk fluid phase diagrams of colloidal mixtures of vanishingly thin hard circular platelets and hard spheres. We find isotropic–nematic phase separation, with strong broadening of the biphasic region, upon increasing the pressure. In mixtures with large size ratio of platelet and sphere diameters, there is also demixing between two nematic phases with differing platelet concentrations. We formulate a fundamental measure density functional for mixtures of colloidal platelets and freely overlapping spheres, which represent ideal polymers, and use it to obtain phase diagrams. We find that, for low platelet–polymer size ratio, in addition to isotropic–nematic and nematic–nematic phase coexistence, platelet–polymer mixtures also display isotropic–isotropic demixing. By contrast, we do not find isotropic–isotropic demixing in hard-core platelet–sphere mixtures for the size ratios considered.
Modifying the structure and flow behaviour of aqueous montmorillonite suspensions with surfactant
Authors: Cui Yannan , Pizzey Claire L. , van Duijneveldt Jeroen S.
Published: March 2013

Colloidal suspensions of plate-like particles undergo a variety of phase transitions. The predicted isotropic/nematic transition is often pre-empted by a sol/gel transition, especially in suspensions of the most commonly used natural swelling clay montmorillonite (MMT). A number of factors, including charge interactions, flexibility and salt concentration, may contribute to this competition. In this study, the effect of surfactant adsorption on suspensions of MMT was studied using rheology, small-angle X-ray scattering, static light scattering and optical microscopy. The addition of a polyetheramine surfactant reduced the moduli of the system and shifted the sol/gel transition to a much higher clay concentration, compared with suspensions of bare clay particles. Yet, scattering data revealed no change in suspension structure on length scales up to around a micrometre. Primary aggregates remain at this length scale and no nematic phase is formed. There is, however, a change in structure at large length scales (of order 20 μm) where light scattering indicates the presence of string-like aggregates that disappear on addition of surfactant. Microscope images of dried suspensions also revealed a string-like structure. The dried strings show strong birefringence and may consist of concentric cylinders, self-assembled from clay sheets.
Mechanical, thermal and colorimetric properties of LLDPE coloured with a blue nanopigment and conventional blue pigments
Authors: Marchante Rodríguez V. , Martínez‐Verdú F.M. , Beltrán Rico M.I. , Marcilla Gomis A.
Published: March 2013

Purpose

This research deals with a new kind of nanopigment, obtained from the combination of organic dyes and layered nanoclays, that the authors call nanoclay‐colorant pigment (NCP). Whilst they have already been employed in inks and coatings, to date these nanopigments have not been used as pigments for polymers. The existing lack of knowledge surrounding them must be redressed in order to bridge the gap between current academic studies and commercial exploitation. Therefore, the main purpose of this paper is to examine the hitherto unknown aspects of the NCP, which relate specifically to their applicability as a new type of colorant for polymers.

Design/methodology/approach

A blue NCP has been prepared at the laboratory according to the patented method of synthesis (patent WO0104216), using methylene blue and montmorillonite nanoclay. It has then been applied to a thermoplastic polymer (linear low‐density polyethylene – LLDPE) to obtain a coloured sample. Furthermore, samples with the same polymer but using conventional blue colorants have been prepared under the same processing conditions. The mechanical, thermal and colorimetric properties of these materials have been compared.

Findings

The thermal stability of the sample coloured with NCP is reduced to some extent, while the mechanical strength is slightly increased. Moreover, this sample has better colour performance than the conventionally pigmented samples.

Originality/value

In this paper, a blue NCP has been synthesised and successfully employed with polyethylene and the obtained sample shows better colour performance than polyethylene with conventional pigments.
Synthesis of urethane acrylate from PENTA based polyol and EB curing with varying ratio of TMTPA
Authors: Deshmukh Pallavi P. , Mahanwar Prakash A. , Sabharwal Sunil S.
Published: March 2013

Purpose

Urethane Acrylate Oligomer with 100% solids was synthesised and characterised in order to study the application in electron beam curing with varying ratio of Trimethylol propane triacrylate (TMPTA). The purpose of this paper is to study effect of TMPTA addition on the crosslink density and different coating properties.

Design/methodology/approach

Polyester polyol was synthesised by reacting single diacid, adipic acid (AA), with Pentaerythritol (PENTA) and 1,6‐hexanediol (HD). Further, Urethane acrylate resin was synthesised by using Isophorone diisocyanate (IPDI), hydroxy ethyl acrylate (HEA) and Polyester polyol. The polyester polyol and urethane acrylate oligomer were characterised by 1H NMR, 13C NMR, FTIR and GPC. Further, TMPTA was added as a crosslinker to the urethane acrylate oligomer and cured by electron beam radiation. The cured UA films having varying concentration of TMPTA were employed to evaluate thermal property, contact angle analysis, mechanical and chemical properties.

Findings

The obtained results showed improvement in their chemical properties, mechanical properties, thermal properties and water contact angle at 20% of TMPTA iconcentration. The TMPTA also reduced the dose required for the curing.

Research limitations/implications

The resin can be synthesised from different isocyanates as TDI, MDI and HMDI, etc. The study can also be done with different multi or mono functional monomers such as methacrylate, hexanediol diacrylate, ethylene glycol diacrylate, etc.

Practical implications

The paper provides the better solution to reduce the cost of the electron beam radiation required for the curing.

Social implications

The method presented in the paper could be very useful for controlling environmental pollution; as the conventional method of curing releases volatile organic compounds (VOC).

Originality/value

In this paper, urethane acrylate and TMTPA cured with electron beam are shown to offer good coating properties. A high‐solid urethane acrylate coating would find numerous industrial applications in surface coatings.
Comparative study on the role of kaolin, calcined kaolin and chemically treated kaolin in alkyd‐based paints for protection of steel
Authors: Ahmed Nivin M.
Published: March 2013

Purpose

Kaolin is a soft white mineral which has a large array of uses. It is most commonly referred to as “China clay”. Sources of this mineral can be found all over the world, its uses are multiple and diverse. It is a mineral belonging to the group of alumino‐silicates with the chemical composition Al2Si2O5(OH)4. It is white, soft, plastic clay mainly composed of plate‐like particles. It is a unique industrial mineral, which remains chemically inert over a relatively wide pH range. The purpose of this paper is to study the difference in performances of untreated or natural kaolin, thermally treated kaolin or so‐called “calcined kaolin” and chemically treated kaolin using ammonium molybdate to convert the γ‐Al2O3 naturally found in kaolin to α‐Al2O3 which possesses one of the most known stable crystalline phases (corundum) in alkyd based anticorrosive paint formulations used for protection of steel.

Design/methodology/approach

The different kaolins were characterized using different analytical and spectro‐photometric techniques. The pigments were characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Evaluation of these pigments using international standard testing methods (ASTM) was estimated. The extender pigments were then incorporated in solvent‐based paint formulations based on medium oil‐modified soya‐bean dehydrated castor oil alkyd resin. The physico‐mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5% NaCl for 28 days were tested.

Findings

The results of this work revealed that calcined kaolin was better in its performance in protection of steel than kaolin, while chemically treated kaolin varied in its performance according to the concentration of modifier or dopant.

Practical implications

Kaolin has a large array of uses. These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent.

Originality/value

The untreated and treated kaolins are environmentally friendly pigments which can impart high anticorrosive behaviour to paint films with concomitant cost saving.
Diels‐Alder adduct of sorbic acid and methyl ester of soyabean oil as substitute to conventional dimer acids
Authors: Malshe V.C. , Phadke Jyoti P. , Jadhav Manisha A.
Published: March 2013

Purpose

The purpose of this paper is to synthesise new fatty dicarboxylic acid half ester (NFAHE) C25, which can be used as substitute to dimer/trimer acids commonly used (C36, 54) as basic raw materials for manufacture of polyamides for printing inks or as curing agents for epoxy paints and adhesives. This could be an economically viable synthesis by which the user could manufacture the finished products from relatively low cost raw materials.

Design/methodology/approach

Vegetable oils have several double bonds that undergo large number of reactions. Diels‐Alder addition is one of them. Dimer acids have been produced by using these double bonds by reaction of two fatty acid molecules. Maleic acid, acrylic acid has also been used for this purpose. Sorbic acid is a derivative of alcohol and hence a renewable raw material. It is relatively less used by the coating chemists due to its relatively limited availability due to restricted uses.

Findings

It was found that sorbic acid reacts easily with unsaturated fatty acids. Its solubility in fatty acids and esters is limited. A common solvent that can be removed easily after the reaction was necessary. Cyclohexanone was found to meet this requirement. The resultant half ester of dicarboxylic acid could be easily converted to polyamides for curing epoxies.

Practical implications

The user can manufacture his own dibasic/tribasic acid as a first step. As a source of methyl esters of fatty acids with iodine value about 110 to 130, vegetable oils such as soyabean oil can be used. Low value acid oils obtained from vegetable oil refining are also suitable. Bio diesel could be used directly. To account for large saturated fatty acids in bio diesel, corresponding trimer may be produced by appropriate addition of sorbic acid to fatty acid.

Originality/value

The process allows a manufacturer to develop low cost formulations for bulk products using simple chemistry that can be integrated in the existing process.
Approximate solutions for Fornberg‐Whitham type equations
Authors: Biazar Jafar , Eslami Mostafa
Published: March 2013

Purpose

The purpose of this study is to propose an analytical approach based on the homotopy perturbation method (HPM) for solving the initial value problems associated with the Fornberg‐Whitham type equations.

Design/methodology/approach

In this paper, He's HPM is applied to Fornberg‐Whitham equations. The procedure of the method is systematically illustrated.

Findings

The results show that the HPM is a powerful mathematical tool to solving these equations, it is also a promising method to solve other nonlinear equations.

Originality/value

The results show applicability, accuracy and efficiency of HPM in solving nonlinear differential equations. It is predicted that HPM can be widely applied in science and engineering problems.