bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Delocalization of Mixed‐Valence Diiron Sites Mediated by Group 10 Metal Ions in Heterotrimetallic Fe‐M‐Fe (M=Ni, Pd, and Pt) Chain Complexes
Authors: Liu Yu‐Chiao , Hua Shao‐An , Cheng Ming‐Chuan , Yu Li‐Chung , Demeshko Serhiy , Dechert Sebastian , Meyer Franc , Lee Gene‐Hsiang , Chiang Ming‐Hsi , Peng Shie‐Ming
Published: June 2018

The heterotrimetallic complexes [FeMFe(dpa)4Cl2] (M=Ni (1), Pd (2), and Pt (3); dpa−=dipyridylamido) featuring two high‐spin iron centers linked by Group 10 metals were synthesized and their physical properties were investigated. Oxidation of 1–3 with suitable oxidants in CH2Cl2 solution yielded the mixed‐valent species [1]+/2+–[3]+/2+. The solution properties of [1]0/+/2+–[3]0/+/2+ were characterized by 1H NMR and UV/Vis/NIR spectroscopy as well as spectroelectrochemisty. The mixed‐valent states of [1]+–[3]+ obtained by electrochemical or chemical oxidation are classified as class II valence delocalization. The solid‐state structures of 1–3, [1]+, [3]+, and [1]2+ were determined by single‐crystal X‐ray diffraction analysis, exhibiting a linear metal framework with an approximate D4 symmetry. The spin states and magnetic properties were studied by using SQUID magnetometry, EPR and Mössbauer spectroscopy, and DFT calculations. Antiferromagnetic interactions between terminal high‐spin iron centers are present within [1]0/+/2+–[3]0/+/2+ and the |J| values increase with the central metal ion changing from Ni to Pt. The DFT calculations reproduce the antiferromagnetic coupling and ascribe it to a σ‐type exchange pathway. The substitution of the central metal not only influences the spin–spin interactions but also the degree of electronic delocalization between the terminal iron sites along the Fe‐M‐Fe chains.
Stepwise Nucleation of Aniline: Emergence of Spectroscopic Fingerprints of the Liquid Phase
Authors: León Iker , Usabiaga Imanol , Arnaiz Pedro F. , Lesarri Alberto , Fernández José A.
Published: June 2018

This work deals with the controlled nucleation of aniline from the isolated molecule until formation of a moderately large aggregate: aniline nonamer. The structure of the cluster at each step of the nucleation was unravelled combining mass‐resolved IR spectroscopy and computational chemistry, demonstrating that aggregation is primarily guided by formation of extensive N−H⋅⋅⋅N hydrogen‐bond networks that give the aggregates a sort of branched backbone, in clear competition with multiple N−H/C−H⋅⋅⋅π and π⋅⋅⋅π interactions. The result is the co‐existence of close nucleation paths connecting relational aggregates. The delicate balance of molecular forces makes the aniline clusters a challenge for molecular orbital calculations and an ideal system to refine the present nucleation models. Noticeably, spectroscopic signatures characteristic of the condensed phase are apparent in the nanometer‐size aggregates formed in this work.
Insight into pH‐Dependent Formation of Manganese Oxide Phases in Electrodeposited Catalytic Films Probed by Soft X‐Ray Absorption Spectroscopy
Authors: Shaker Maryam N. , Bonke Shannon A. , Xiao Jie , Khan Munirah A. , Hocking Rosalie K. , Tesch Marc F.
Published: June 2018

MnOx films electrodeposited under basic, neutral, and acidic conditions from an ionic liquid were investigated by means of X‐ray absorption spectroscopy at the manganese L2,3‐edges and the oxygen K‐edge. Such films can serve as catalysts for the water oxidation reaction. Previous studies showed that the catalytic activity could be controlled by varying the deposition parameters, which influence the formation of MnOx phases and the film composition. Herein the film compositions are investigated in detail, indicating different ratios of MnOx structural phases in the films. All films in the series predominately consist of varying proportions of three MnOx phases—Mn2O3, Mn3O4, and birnessite, while an increase of the average Mn oxidation state in the film is identified when going from basic to acidic conditions during electrodeposition. The contribution of these three phases shows a systematic dependency on the pH during electrodeposition. While no specific single MnOx phase was found to dominate the composition of samples that were previously found to show high catalytic activity, the X‐ray spectroscopic results revealed the compositions of those samples prepared under close to neutral conditions to be most sensitive to changes in pH.
A Method for Isolating and Characterizing Mesenchymal Stromal Cell‐derived Extracellular Vesicles
Authors: Lo Sicco Claudia , Reverberi Daniele , Pascucci Luisa , Tasso Roberta
Published: June 2018

The unit describes protocols for isolating and characterizing extracellular vesicles (EVs) derived from human adipose tissue‐derived mesenchymal stromal cells (MSCs). EVs are a mixed population of membrane‐surrounded structures with overlapping composition and size. Advances made in recent years have led to a better understanding of the biological role of EVs. In particular, they can be considered key factors responsible for MSC‐paracrine activity, mediating their anti‐inflammatory effects towards innate immune cells, such as macrophages.

The topics comprise description of the MSC‐conditioned medium containing vesicles preparation, EV isolation, and characterization mainly by specifically set up flow cytometry and electron microscopy approaches, and in vitro methodologies involved in testing the EV anti‐inflammatory capacity. The procedures described here can be easily reproduced and can be employed regardless of the type of progenitor cells used to secrete EVs. © 2018 by John Wiley & Sons, Inc.
Power splitting–based energy‐harvesting protocol for wireless‐powered communication networks with a bidirectional relay
Authors: Nguyen Tan N. , Tran Phuong T. , Vozňák Miroslav
Published: June 2018

In this paper, we apply the power splitting–based energy‐harvesting protocol to enhance the transmission between a wireless access point and a mobile user via a helping relay. The mobile user exploits the energy supplied by the access point and forwarded by the relay to transmit its own data back to the access point, again with the helping of the relay. Here, the effect of various system parameters, including power‐splitting factor and the power‐to‐noise ratio on the system performance, is rigorously studied, with closed‐form expressions for the outage probability and system throughput as the results. Furthermore, we figure out the optimal power‐splitting ratio at which the information throughput from the user to the AP is maximized, subject to the constraint on the transmitting power at the access point. All above analytical results are also supported by Monte Carlo simulation.
Shoal size as a key determinant of vulnerability to capture under a simulated fishery scenario
Authors: Thambithurai Davide , Hollins Jack , Van Leeuwen Travis , Rácz Anita , Lindström Jan , Parsons Kevin , Killen Shaun S.
Published: June 2018

Group living is widespread among animals and has a range of positive effects on individual foraging and predator avoidance. For fishes, capture by humans constitutes a major source of mortality, and the ecological effects of group living could carry‐over to harvest scenarios if fish are more likely to interact with fishing gears when in social groups. Furthermore, individual metabolic rate can affect both foraging requirements and social behaviors, and could, therefore, have an additional influence on which fish are most vulnerable to capture by fishing. Here, we studied whether social environment (i.e., social group size) and metabolic rate exert independent or interactive effects on the vulnerability of wild zebrafish (Danio rerio) to capture by a baited passive trap gear. Using video analysis, we observed the tendency for individual fish to enter a deployed trap when in different shoal sizes. Fish in larger groups were more vulnerable to capture than fish tested individually or at smaller group sizes. Specifically, focal fish in larger groups entered traps sooner, spent more total time within the trap, and were more likely to re‐enter the trap after an escape. Contrary to expectations, there was evidence that fish with a higherSMRtook longer to enter traps, possibly due to a reduced tendency to follow groupmates or attraction to conspecifics already within the trap. Overall, however, social influences appeared to largely overwhelm any link between vulnerability and metabolic rate. The results suggest that group behavior, which in a natural predation setting is beneficial for avoiding predators, could be maladaptive under a trap harvest scenario and be an important mediator of which traits are under harvest associated selection.
Predator–prey interactions in a ladybeetle–aphid system depend on spatial scale
Authors: Lin Wei‐Ting , Pennings Steven C.
Published: June 2018

The outcome of species interactions may manifest differently at different spatial scales; therefore, our interpretation of observed interactions will depend on the scale at which observations are made. For example, in ladybeetle–aphid systems, the results from small‐scale cage experiments usually cannot be extrapolated to landscape‐scale field observations. To understand how ladybeetle–aphid interactions change across spatial scales, we evaluated predator–prey interactions in an experimental system. The experimental habitat consisted of 81 potted plants and was manipulated to facilitate analysis across four spatial scales. We also simulated a spatially explicit metacommunity model parallel to the experiment. In the experiment, we found that the negative effect of ladybeetles on aphids decreased with increasing spatial scales. This pattern can be explained by ladybeetles strongly suppressing aphids at small scales, but not colonizing distant patches fast enough to suppress aphids at larger scales. In the experiment, the positive effects of aphids on ladybeetles were strongest at three‐plant scale. In a model scenario where predators did not have demographic dynamics, we found, consistent with the experiment, that both the effects of ladybeetles on aphids and the effects of aphids on ladybeetles decreased with increasing spatial scales. These patterns suggest that dispersal was the primary cause of ladybeetle population dynamics in our experiment: aphids increased ladybeetle numbers at smaller scales because ladybeetles stayed in a patch longer and performed area‐restricted searches after encountering aphids; these behaviors did not affect ladybeetle numbers at larger spatial scales. The parallel experimental and model results illustrate how predator–prey interactions can change across spatial scales, suggesting that our interpretation of observed predator–prey dynamics would differ if observations were made at different scales. This study demonstrates how studying ecological interactions at a range of scales can help link the results of small‐scale ecological experiments to landscape‐scale ecological problems.
Rivers shape population genetic structure in Mauritia flexuosa (Arecaceae)
Authors: Sander Nilo L. , Pérez‐Zavala Francisco , Da Silva Carolina J. , Arruda Joari C. , Pulido Maria T. , Barelli Marco A. A. , Rossi Ana B. , Viana Alexandre P. , Boechat Marcela S. B. , Bacon Christine D. , Cibrián‐Jaramillo Angélica
Published: June 2018

The Mauritia flexuosa L.f. palm is known as the “tree of life” given its importance as fundamental food and construction resources for humans. The species is broadly distributed in wet habitats of Amazonia and dry habitats of the Amazon and Orinoco river basins and in the Cerrado savanna. We collected 179 individuals from eight different localities throughout these habitats and used microsatellites to characterize their population structure and patterns of gene flow. Overall, we found high genetic variation, except in one savanna locality. Gene flow between populations is largely congruent with river basins and the direction of water flow within and among them, suggesting their importance for seed dispersal. Further, rivers have had a higher frequency of human settlements than forested sites, contributing to population diversity and structure through increased human use and consumption of M. flexuosa along rivers. Gene flow patterns revealed that migrants are sourced primarily from within the same river basin, such as those from Madeira and Tapajós basins. Our work suggests that rivers and their inhabitants are a critical element of the landscape in Amazonia and have impacted the dispersal and subsequent distribution of tropical palm species, as shown by the patterns of genetic variation in M. flexuosa.
Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild
Authors: D'Amore Domenic C. , Clulow Simon , Doody J. Sean , Rhind David , McHenry Colin R.
Published: June 2018

Numerous studies investigate morphology in the context of habitat, and lizards have received particular attention. Substrate usage is often reflected in the morphology of characters associated with locomotion, and, as a result, claws have become well‐studied ecomorphological traits linking the two. The Kimberley predator guild of Western Australia consists of 10 sympatric varanid species. The purpose of this study was to quantify claw size and shape in the guild using geometric morphometrics, and determine whether these features correlated with substrate use and habitat. Each species was assigned a Habitat/substrate group based on the substrate their claws interact with in their respective habitat. Claw morphometrics were derived for both wild caught and preserved specimens from museum collections, using a 2D semilandmark analysis. Claw shape significantly separated based on Habitat/substrate group. Varanus gouldii and Varanus panoptes claws were associated with sprinting and extensive digging. Varanus mertensi claws were for shallow excavation. The remaining species’ claws reflected specialization for some form of climbing, and differed based on substrate compliance. Varanus glauerti was best adapted for climbing rough sandstone, whereas Varanus scalaris and Varanus tristis had claws ideal for puncturing wood. Phylogenetic signal also significantly influenced claw shape, with Habitat/substrate group limited to certain clades. Positive size allometry allowed for claws to cope with mass increases, and shape allometry reflected a potential size limit on climbing. Claw morphology may facilitate niche separation within this trophic guild, especially when considered with body size. As these varanids are generalist predators, morphological traits associated with locomotion may be more reliable candidates for detecting niche partitioning than those associated directly with diet.
A dominance shift in arid savanna: An herbaceous legume outcompetes local C4 grasses
Authors: Wagner Thomas C. , Richter Johanna , Joubert David F. , Fischer Christina
Published: June 2018

The characteristic vegetation structure of arid savannas with a dominant layer of perennial grass is maintained by the putative competitive superiority of the C4 grasses. When this competitive balance is disturbed by weakening the grasses or favoring the recruitment of other species, trees, shrubs, single grass, or forb species can increase and initiate sudden dominance shifts. Such shifts involving woody species, often termed “shrub encroachment”, or the mass spreading of so‐called increaser species have been extensively researched, but studies on similar processes without obvious preceding disturbance are rare. In Namibia, the native herbaceous legume Crotalaria podocarpa has recently encroached parts of the escarpment region, seriously affecting the productivity of local fodder grasses. Here, we studied the interaction between seedlings of the legume and the dominant local fodder grass (Stipagrostis ciliata). We used a pot experiment to test seedling survival and to investigate the growth of Crotalaria in competition with Stipagrostis. Additional field observations were conducted to quantify the interactive effect. We found germination and growth of the legume seedlings to be facilitated by inactive (dead or dormant) grass tussocks and unhindered by active ones. Seedling survival was three times higher in inactive tussocks and Crotalaria grew taller. In the field, high densities of the legume had a clear negative effect on productivity of the grass. The C4 grass was unable to limit the recruitment and spread of the legume, and Crotalaria did outcompete the putative more competitive grass. Hence, the legume is able to spread and establish itself in large numbers and initiate a dominance shift in savannas, similar to shrub encroachment.
Where eagles soar: Fine‐resolution tracking reveals the spatiotemporal use of differential soaring modes in a large raptor
Authors: Murgatroyd Megan , Photopoulou Theoni , Underhill Les G. , Bouten Willem , Amar Arjun
Published: June 2018

Unlike smaller raptors, which can readily use flapping flight, large raptors are mainly restricted to soaring flight due to energetic constraints. Soaring comprises of two main strategies: thermal and orographic soaring. These soaring strategies are driven by discrete uplift sources determined by the underlying topography and meteorological conditions in an area. High‐resolution GPS tracking of raptor flight allows the identification of these flight strategies and interpretation of the spatiotemporal occurrence of thermal and orographic soaring. In this study, we develop methods to identify soaring flight behaviors from high‐resolution GPS tracking data of Verreaux’s eagle Aquila verreauxii and analyze these data to understand the conditions that promote the use of thermal and orographic soaring. We use these findings to predict the use of soaring flight both spatially (across the landscape) and temporally (throughout the year) in two topographically contrasting regions in South Africa. We found that topography is important in determining the occurrence of soaring flight and that thermal soaring occurs in relatively flat areas which are likely to have good thermal uplift availability. The predicted use of orographic soaring was predominately determined by terrain slope. Contrary to our expectations, the topography and meteorology of eagle territories in the Sandveld promoted the use of soaring flight to a greater extent than in territories in the more mountainous Cederberg region. Spatiotemporal mapping of predicted flight behaviors can broaden our understanding of how large raptors like the Verreaux’s eagle use their habitat and how that links to energetics (as the preferential use of areas that maximize net energy gain is expected), reproductive success, and ultimately population dynamics. Understanding the fine‐scale landscape use and environmental drivers of raptor flight can also help to predict and mitigate potential detrimental effects of anthropogenic developments, such as mortality via collision with wind turbines.
Climate stability is more important than water–energy variables in shaping the elevational variation in species richness
Authors: Gao Jie , Liu Yanhong
Published: June 2018

Changes in climate variables have an important impact on the prediction and protection of elevational biodiversity. Gaps exist in our understanding of the elevational distribution patterns in seed plant species richness. Our study examines the importance of climate variables in shaping the elevational variation in species richness. The importance of boundary constraint was also taken into account. Model selection based on Akaike's information criterion was used to select the best explaining climate models. Variation partitioning was used to assess the independent and joint effects of water–energy, physiological tolerance, and environmental stability variables on species richness. Our results revealed that: (a) Both raw (boundary constraint unreduced) and estimated (boundary constraint reduced) species richness showed large elevational variation, with the peak species richness seen at midelevations. The environmental variables were better at explaining the distribution pattern of species richness along the elevation, when the effect of boundary constraint was reduced; (b) the physiological tolerance and environmental stability variables explained more variation in raw and estimated species richness compared with the water–energy variables. Estimated species richness was better explained (98.6%) by the environmental variables than raw species richness (94%); (c) the water‐related variables generally had the highest independent effect on raw and estimated species richness and were dominant in shaping the elevational variation in species richness. Our findings quantify the influence of boundary constraint on the distribution pattern of species along an altitudinal gradient and compare the relative contributions of environmental stability and water–energy in explaining the altitude gradient distribution pattern of plant seed species.
On the possible role of nonreproductive traits for the evolution of unisexuality: Life‐history variation among males, females, and hermaphrodites in Opuntia robusta (Cactaceae)
Authors: del Castillo Rafael F. , Trujillo‐Argueta Sonia
Published: June 2018

In angiosperms, dioecy has arisen in 871–5,000 independent events, distributed in approximately 43% of the flowering families. The reproductive superiority of unisexuals has been the favorite explanation for the evolution of separate sexes. However, in several instances, the observed reproductive performance of unisexuals, if any, does not seem to compensate for the loss of one of the sex functions. The involvement of fitness components not directly associated with reproduction is a plausible hypothesis that has received little attention. Life‐history traits recently recognized as predictors of plant performance were compared among males, females, and hermaphrodites of a rare trioecious Opuntia robusta population in the field, using the cladode as the study unit. Cladode mortality by domestic herbivores was common and higher in females and hermaphrodites than in males. Males, females, or both displayed lower shrinkage and higher rates of survival, growth, and reproductive frequency than hermaphrodites. Unisexuals simultaneously outperformed hermaphrodites in demographic traits known to compete for common limiting resources, such as the acceleration of reproductive maturation (progenesis) and survival. A meta‐analysis combining the outcomes of each of the analyzed life‐history traits revealed a tendency of males (d++ = 1.03) and females (d++ = 0.93) to outperform hermaphrodites in presumably costly demographic options. Clonality is induced by human or domestic animal plant sectioning; and males and females highly exceeded hermaphrodites in their clonality potential by a factor of 8.3 and 5.3, respectively. The performances of unisexuals in the analyzed life‐history traits may enhance their reproductive potential in the long run and their clonality potential and could explain the observed increase of unisexuality in the population. Life‐history traits can be crucial for the evolution of unisexuality, but their impact appears to be habitat specific and may involve broad ontogenetic changes.
PMERGE: Computational filtering of paralogous sequences from RAD‐seq data
Authors: Nadukkalam Ravindran Praveen , Bentzen Paul , Bradbury Ian R. , Beiko Robert G.
Published: June 2018

Restriction‐site associated DNA sequencing (RAD‐seq) can identify and score thousands of genetic markers from a group of samples for population‐genetics studies. One challenge of de novo RAD‐seq analysis is to distinguish paralogous sequence variants (PSVs) from true single‐nucleotide polymorphisms (SNPs) associated with orthologous loci. In the absence of a reference genome, it is difficult to differentiate true SNPs from PSVs, and their impact on downstream analysis remains unclear. Here, we introduce a network‐based approach, PMERGE that connects fragments based on their DNA sequence similarity to identify probable PSVs. Applying our method to de novo RAD‐seq data from 150 Atlantic salmon (Salmo salar) samples collected from 15 locations across the Southern Newfoundland coast allowed the identification of 87% of total PSVs identified through alignment to the Atlantic salmon genome. Removal of these paralogs altered the inferred population structure, highlighting the potential impact of filtering in RAD‐seq analysis. PMERGE is also applied to a green crab (Carcinus maenas) data set consisting of 242 samples from 11 different locations and was successfully able to identify and remove the majority of paralogous loci (62%). The PMERGE software can be run as part of the widely used Stacks analysis package.
Glycaemic impact of treatment intensification in patients with type 2 diabetes uncontrolled with oral antidiabetes drugs or basal insulin
Authors: Buysman Erin K. , Fan Tao , Blauer‐Peterson Cori , Miller‐Wilson Lesley‐Ann
Published: June 2018

Aims

To investigate the impact of treatment intensification (TI) on glycaemic outcomes in patients with type 2 diabetes with glycated haemoglobin A1c (A1C) ≥7% after ≥6 months of treatment with 2 oral antidiabetes drugs (OADs) or basal insulin (BI).

Materials and Methods

Data were extracted from the Optum administrative claims database from 1 January 2009 to 31 August 2015. Patients with TI ≤6 months after the first A1C ≥7% (index date) were compared with patients with no TI (NTI). TI included addition of OAD, GLP‐1 receptor agonist or premixed insulin in OAD and BI cohorts, addition of BI and/or bolus insulin in the OAD cohort and addition of bolus insulin or increasing BI dose in the BI cohort. Change from the index A1C value and hypoglycaemia events was compared at 12 months after TI after adjusting for confounders.

Results

A total of 3990/28 123 (14.2%) and 10 425/16 140 (65%) of eligible adults in the OAD and BI cohorts, respectively, underwent TI. These patients showed greater adjusted A1C change vs NTI patients (OAD cohort: −0.59% vs −0.25%; BI cohort: −0.30% vs −0.16%; P < .001 for both comparisons), but with higher hypoglycaemia rates (OAD cohort: odds ratio [OR] 1.68; P < .001; BI cohort: OR: 1.23; P = .004) at follow‐up.

Conclusions

Clinical inertia appears to be a significant issue in this population. Although associated with more frequent hypoglycaemia, these results demonstrate that timely TI improves A1C levels, highlighting the need for new and improved agents to effectively manage glycaemia while reducing hypoglycaemia risk.
Reactivity of Alkyne Insertion and Catalytic Activity of Five‐ and Six‐Membered Cyclometalated Phosphine Complexes of Iridium
Authors: Li Tongyu , Wang Zhuo , Liu Kai , Xing Siyang , Zhu Bolin
Published: June 2018

Reactions of three aryl‐substituted phosphines with [Cp*IrCl2]2 afforded the corresponding five‐membered or six‐membered cyclometalated iridium complexes (2 or 5,6) via an intramolecular C(sp2)–H bond activation. Insertion reactions of the five‐membered cycloiridated complex 2 with PhC≡CPh and PhC≡CCOPh resulted in the corresponding five‐membered and six‐membered doubly cycloiridated complexes 7 and 8, the formation of which presumably went through the vinylidene rearrangement of alkynes followed by 1,1‐insertion; while the reactions of the six‐membered cyclometalated complexes 5, 6 with PhC≡CPh or PhC≡CCOPh gave the corresponding eight‐membered cycloiridated complexes 9–12 by 1,2‐insertion. The hydrosilylation of imines catalyzed by five‐ or six‐membered P‐containing cycloiridated complexes were studied, and the results proved that the six‐membered cycloiridated complex 5 can be used as an efficient catalyst, which was applied for the hydrosilylation of various imines, especially aldimines. Molecular structures of complexes 9, 10 and 12 were determined by X‐ray diffraction.
Heteroarene N‐Oxides as Oxygen Source in Organic Reactions
Authors: Petrosyan Andranik , Hauptmann Richy , Pospech Jola
Published: June 2018

This review summarizes the utilization of heteroarene N‐oxides as oxidant in organic reactions. The specific focus lies on reactions in which pyridine N‐oxides are used as oxygen source in an oxygen atom transfer fashion. The scope comprises the hydroxylation of aliphatic and aromatic C–H bonds, epoxidation as well as oxygenations of alkenes and alkynes. The latter have been extensively reviewed elsewhere and are merely discussed in a conceptual manner.
Hydrate Formation Characteristics during Carbon Dioxide Flow Through Depleted Methane Hydrate Deposits
Authors: Wang Pengfei , Zhou Hang , Ling Zheng , Li Yuanping
Published: June 2018

Depleted methane hydrate (MH) reservoirs are potential sites for CO2 storage. Hydrate formation during the CO2 flow process in a dissociated MH sample was simulated to clarify the formation characteristics of CO2 hydrates and their effect on CO2 storage. Experiments included MH formation and dissociation, CO2 injection, water‐injection and CO2 hydrate dissociation, and liquid‐water distribution as monitored by magnetic resonance imaging (MRI). It was observed that the initial water saturation determined the hydrate saturation in the artificial sediment, and the depressurization range was the main factor influencing MH dissociation for the excess gas sample. Pressure is the key factor influencing hydrate formation during CO2 flow. An increase of the CO2 flow rate led to a decrease of both hydrate saturation and conversion of the injected CO2. The cumulative amount of injected water is not the key factor controlling CO2 hydrate formation, but it does determine the residual water saturation.
Effects of variation in loading protocol on the strength and deformation capacity of ductile reinforced concrete beams
Authors: Marder Kai J. , Motter Christopher J. , Elwood Kenneth J. , Clifton G. Charles
Published: June 2018

Understanding the impact of prior earthquake damage on residual capacity is important for postearthquake damage assessment of buildings; however, interpretation of such impact is challenging when based on tests using traditional reversed‐cyclic loading protocols. A new loading protocol, consisting of a dynamic earthquake displacement history followed by quasi‐static reversed‐cyclic loading to failure, is presented as an alternative to traditional simulated seismic loading protocols. Data are analyzed from a set of 12 nominally identical ductile reinforced concrete beams that were tested by using variations of this protocol and traditional reversed‐cyclic and monotonic protocols. Differences in the cycle content of the earthquake displacement histories applied to the test specimens allowed for the effects of load history variation below 2.2% drift to be isolated. It is found that such variation had no effect on the beam deformation capacities. The effects of dynamic loading rates are also analyzed and compared against control quasi‐static specimens. Relative strength increases due to dynamic loading are found to be more significant at yield than at ultimate. Dynamic loading rates led to modest reductions in the beam deformation capacities, but the presence of causality between these variables remains uncertain.
Ablation behavior of organoclay‐NBR insulator: Modeling and experimental
Authors: Arabgol Fatemeh , Kokabi Mehrdad , Bahramian Ahmad Reza
Published: June 2018

Nitrile‐based nanocomposite heat insulators are very attractive materials compared with their similar nonelastomeric counterparts, due to their higher deformation bearing capacity in special applications. Modeling of these ablative nanocomposites enables us to determine the exact required thickness of the insulator and temperature distribution across it at predetermined thermal conditions. The complete form of the ablation equation is a transient nonlinear second‐order differential equation with variable temperature‐dependent thermo‐physical properties, which must be determined during thermal degradation. In this work, in addition to experimental investigation of ablative elastomeric nanocomposites based on NBR, the ablation process is modeled analytically with perturbation theory in the Lagrangian coordinate system because of surface recession and moving boundaries. Kirchhoff transformation was used to get rid of the temperature dependence of k in each zonal of virgin and char. The theoretical results were confirmed by experimental data obtained from the oxyacetylene flame test. The results proposed a competitive nitrile‐based nanocomposite heat insulator with superior ablation properties: mass ablation rate 0.014 g s−1, linear ablation rate 0.012 mm s−1, and insulating index number 6800 s m−1, under a standard test with a heat flux of 2500 kW m−2 for 15 seconds.
Mitigation of greenhouse gas emissions from animal production
Authors: Liu Zifei , Liu Yang
Published: June 2018

The accurate quantification of the carbon footprints of animal products and the related development of greenhouse gas (GHG) mitigation strategies are of interest to consumers, the general public, and the academic community. The objective of this review was to summarize recent advances in GHG emission quantification, life‐cycle assessment applications, and mitigation technologies for animal production in the USA, to assist the development of system‐based solutions for mitigation of GHG emissions from animal production. The GHG emissions from animal production mainly come from feed production, enteric fermentation, and manure management. Opportunities to mitigate emissions from feed production largely rely on continuous improvements in animal and feed production efficiency. This is in general agreement with the economic interest of the industry. To mitigate emissions from manure, many technologies can be chosen, depending on the given economic and regulatory environments. It is possible to minimize GHG emissions from manure through manure energy recovery when this is economically feasible. For enteric emissions, there are limited opportunities to reduce GHG emissions through dietary manipulation, feed management, or feed supplementations. Improving environmental stewardship of consumers and reducing food waste will reduce animal protein demand and are important bottom‐line strategies to mitigate GHG from animal production systems. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.
Numerical study of heat transfer enhancement using perforated dual twisted tape inserts in converging‐diverging tubes
Authors: Afsharpanah Farhad , Pakzad Khashayar , Amirsoleymani Mehrshad , Delavar Mojtaba Aghajani
Published: June 2018

In this article, a 3D numerical simulation for investigating friction factor and heat transfer enhancements in case of inserting normal or perforated dual twisted tapes (TTs) in converging‐diverging tubes (CDTs) is presented. The effects of Reynolds number changing from 10,000 to 20,000 and a various number of holes (N = 0, 1, 2, and 3) in TTs, under constant uniform heat flux on tube outer wall and using water as working fluid circumstances, were examined. It was found that generally using dual TTs in CDTs improves the Nusselt number up to 9% compared to bare CDTs. Perforating TTs do not have a noticeable effect on heat transfer, but decrease the friction factor significantly, up to 396% compared to normal dual TT implantation, in higher Reynolds numbers. Following that, thermal performance factor considerably increases up to 57%, compared to CDTs with normal dual TTs. To show the mechanism of these effects, velocity streamlines are presented and will be discussed in this paper.
Fast and flexible gpu accelerated binding free energy calculations within the amber molecular dynamics package
Authors: Mermelstein Daniel J. , Lin Charles , Nelson Gard , Kretsch Rachael , McCammon J. Andrew , Walker Ross C.
Published: June 2018

Alchemical free energy (AFE) calculations based on molecular dynamics (MD) simulations are key tools in both improving our understanding of a wide variety of biological processes and accelerating the design and optimization of therapeutics for numerous diseases. Computing power and theory have, however, long been insufficient to enable AFE calculations to be routinely applied in early stage drug discovery. One of the major difficulties in performing AFE calculations is the length of time required for calculations to converge to an ensemble average. CPU implementations of MD‐based free energy algorithms can effectively only reach tens of nanoseconds per day for systems on the order of 50,000 atoms, even running on massively parallel supercomputers. Therefore, converged free energy calculations on large numbers of potential lead compounds are often untenable, preventing researchers from gaining crucial insight into molecular recognition, potential druggability and other crucial areas of interest. Graphics Processing Units (GPUs) can help address this. We present here a seamless GPU implementation, within the PMEMD module of the AMBER molecular dynamics package, of thermodynamic integration (TI) capable of reaching speeds of >140 ns/day for a 44,907‐atom system, with accuracy equivalent to the existing CPU implementation in AMBER. The implementation described here is currently part of the AMBER 18 beta code and will be an integral part of the upcoming version 18 release of AMBER. © 2018 Wiley Periodicals, Inc.
Coarse‐grained molecular dynamics simulations of polymerization with forward and backward reactions
Authors: Krajniak Jakub , Zhang Zidan , Pandiyan Sudharsan , Nies Eric , Samaey Giovanni
Published: June 2018

We develop novel parallel algorithms that allow molecular dynamics simulations in which byproduct molecules are created and removed because of the chemical reactions during the molecular dynamics simulation. To prevent large increases in the potential energy, we introduce the byproduct molecules smoothly by changing the non‐bonded interactions gradually. To simulate complete equilibrium reactions, we allow the byproduct molecules attack and destroy created bonds. Modeling of such reactions are, for instance, important to study the pore formation due to the presence of e.g. water molecules or development of polymer morphology during the process of splitting off byproduct molecules. Another concept that could be studied is the degradation of polymeric materials, a very important topic in a recycling of polymer waste. We illustrate the method by simulating the polymerization of polyethylene terephthalate (PET) at the coarse‐grained level as an example of a polycondensation reaction with water as a byproduct. The algorithms are implemented in a publicly available software package and are easily accessible using a domain‐specific language that describes chemical reactions in an input configuration file. © 2018 Wiley Periodicals, Inc.
Perfect divisibility and 2‐divisibility
Authors: Chudnovsky Maria , Sivaraman Vaidy
Published: June 2018

A graph G is said to be 2‐divisible if for all (nonempty) induced subgraphs H of G, can be partitioned into two sets such that and . (Here denotes the clique number of G, the number of vertices in a largest clique of G). A graph G is said to be perfectly divisible if for all induced subgraphs H of G, can be partitioned into two sets such that is perfect and . We prove that if a graph is ‐free, then it is 2‐divisible. We also prove that if a graph is bull‐free and either odd‐hole‐free or P5‐free, then it is perfectly divisible.
Successful fishing for nucleus pulposus progenitor cells of the intervertebral disc across species
Authors: Sakai Daisuke , Schol Jordy , Bach Frances C. , Tekari Adel , Sagawa Nobuho , Nakamura Yoshihiko , Chan Samantha C.W. , Nakai Tomoko , Creemers Laura B. , Frauchiger Daniela A. , May Rahel D. , Grad Sibylle , Watanabe Masahiko , Tryfonidou Marianna A. , Gantenbein Benjamin
Published: June 2018

Background

Recently, Tie2/TEK receptor tyrosine kinase (Tie2 or syn. angiopoietin‐1 receptor) positive nucleus pulposus progenitor cells were detected in human, cattle, and mouse. These cells show remarkable multilineage differentiation capacity and direct correlation with intervertebral disc (IVD) degeneration and are therefore an interesting target for regenerative strategies. Nevertheless, there remains controversy over the presence and function of these Tie2+ nucleus pulposus cells (NPCs), in part due to the difficulty of identification and isolation.

Purpose

Here, we present a comprehensive protocol for sorting of Tie2+ NPCs from human, canine, bovine, and murine IVD tissue. We describe enhanced conditions for expansion and an optimized fluorescence‐activated cell sorting‐based methodology to sort and analyze Tie2+ NPCs.

Methods

We present flow cytometry protocols to isolate the Tie2+ cell population for the aforementioned species. Moreover, we describe crucial pitfalls to prevent loss of Tie2+ NPCs from the IVD cell population during the isolation process. A cross‐species phylogenetic analysis of Tie2 across species is presented.

Results

Our protocols are efficient towards labeling and isolation of Tie2+ NPCs. The total flow cytometry procedure requires approximately 9 hours, cell isolation 4 to 16 hours, cell expansion can take up to multiple weeks, dependent on the application, age, disease state, and species. Phylogenetic analysis of the TEK gene revealed a strong homology among species.

Conclusions

Current identification of Tie2+ cells could be confirmed in bovine, canine, mouse, and human specimens. The presented flow cytometry protocol can successfully sort these multipotent cells. The biological function of isolated cells based on Tie2+ expression needs to be confirmed by functional assays such as in vitro differentiation. in vitro culture conditions to maintain and their possible proliferation of the Tie2+ fraction is the subject of future research.
Silver Loaded Nanofibrous Curdlan Mat for Diabetic Wound Healing: An In Vitro and In Vivo Study
Authors: Yunus Basha Rubaiya , Sampath Kumar T. S. , Selvaraj Ramasamy , Doble Mukesh
Published: June 2018

A fibrous scaffold of curdlan/poly(vinyl alcohol) (PVA) blend is prepared by electrospinning technique and antimicrobial property is imparted to it by the addition of silver nitrate (1, 3, and 5 wt%). All the scaffolds except the PVA/curdlan with 5 wt% AgNO3 show good viability of Swiss 3T3 fibroblast cells. Significant reductions in the growth of Staphylococcus aureus and Escherichia coli are also observed in all the scaffolds. In vitro scratch assay and cell adhesion studies indicate that the scaffold containing 1% AgNO3 shows significant wound healing and better cell spreading. The in vivo results also show faster healing of excision wounds in diabetic rats treated with the same material when compared to the control and the commercial sample. Furthermore, downregulation of proinflammatory cytokines and upregulation of anti‐inflammatory cytokines on the skin of the treated animals confirm that PVA/curdlan/1% AgNO3 electrospun mat could be a promising material for diabetic wound healing.
Proteomics biomarkers for solid tumors: Current status and future prospects
Authors: Belczacka Iwona , Latosinska Agnieszka , Metzger Jochen , Marx David , Vlahou Antonia , Mischak Harald , Frantzi Maria
Published: June 2018

Cancer is a heterogeneous multifactorial disease, which continues to be one of the main causes of death worldwide. Despite the extensive efforts for establishing accurate diagnostic assays and efficient therapeutic schemes, disease prevalence is on the rise, in part, however, also due to improved early detection. For years, studies were focused on genomics and transcriptomics, aiming at the discovery of new tests with diagnostic or prognostic potential. However, cancer phenotypic characteristics seem most likely to be a direct reflection of changes in protein metabolism and function, which are also the targets of most drugs. Investigations at the protein level are therefore advantageous particularly in the case of in‐depth characterization of tumor progression and invasiveness. Innovative high‐throughput proteomic technologies are available to accurately evaluate cancer formation and progression and to investigate the functional role of key proteins in cancer. Employing these new highly sensitive proteomic technologies, cancer biomarkers may be detectable that contribute to diagnosis and guide curative treatment when still possible. In this review, the recent advances in proteomic biomarker research in cancer are outlined, with special emphasis placed on the identification of diagnostic and prognostic biomarkers for solid tumors. In view of the increasing number of screening programs and clinical trials investigating new treatment options, we discuss the molecular connections of the biomarkers as well as their potential as clinically useful tools for diagnosis, risk stratification and therapy monitoring of solid tumors.
Advanced Short‐Term Approaches to Estimate the Long‐Term Mechanical Behavior of Polymers at Static Loading Conditions
Authors: Nezbedova Eva , Lach Ralf , Grellmann Wolfgang
Published: June 2018

Conventional methods for testing the long‐term resistance against creep and slow crack growth (SCG) become more and more unusable for highly improved polymers due to the required long times of often more than 1 year. Therefore, there is a great need for developing new time‐saving methods for predicting the lifetime of such polymers. In this study, the authors describe one of these methods in more detail. The strain hardening method (SHM) is based on uniaxial tensile testing to estimate the time to failure. It has been shown that the strain hardening modulus can be easily determined using SHM with testing times of only a few hours. Due to the same molecular processes during SHM and conventional methods such as full notch creep test (FNCT) and Pennsylvania edge notch tensile (PENT) test, the strain hardening modulus covers the SCG resistance in pipe‐grade high‐density polyethylenes (PE‐HD) to a high degree.
Nanocomposites of Polyaniline with Silver Nanoparticles Prepared Using Water in Oil Microemulsions as Antibacterial Agents
Authors: Fatema Ummul K. , Rahman M. Muhibur , Islam M. Rakibul , Mollah M. Yousuf A. , Susan Md Abu Bin Hasan
Published: June 2018

Polyaniline (PAni) was synthesized by chemical oxidative polymerization of aniline monomer by ammonium peroxydisulfate using w/o microemulsion and from aqueous solution. Ag/PAni nanocomposites were then prepared using w/o microemulsion by the same polymerization method in pre‐formed Ag nanoparticles prepared by the reduction of metal salts in microemulsion. PAni and Ag/PAni nanocomposites were characterized by UV‐visible and Fourier transform infrared (FTIR) spectroscopy. Dynamic light scattering (DLS) results and scanning electron microscopic (SEM) SEM images showed that PAni synthesized in microemulsion was smaller in particle dimension than that obtained from the bulk. Thermogravimetric analysis (TGA) results showed that PAni from microemulsion has a lower thermal stability than PAni from bulk synthesis. Ag/PAni nanocomposites, however, showed somewhat better thermal stability compared to that of PANI from microemulsion. The antibacterial properties against Gram‐negative, Escherichia coli and Gram‐positive, Staphylococcus aureus were tested by zone of inhibition method and the results demonstrated that Ag/PAni nanocomposites have enhanced antibacterial efficiency compared to PAni generated in microemulsion which is more efficient than PAni prepared from aqueous solution.