bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk, politics, and science: A new approach to UK marine biodiversity monitoring.
Authors: Webb Karen E , Hinchen Hayley
Published: March 2018

The UK recognises the importance of understanding marine ecosystems and biodiversity to achieve its ambition of ‘clean, healthy, safe and biologically diverse seas’. Yet comprehensive UK marine monitoring presents a considerable challenge in terms of the resources required. The Joint Nature Conservation Committee has led the development of an ambitious framework for marine monitoring that will integrate the different components of biodiversity together, and with other marine monitoring. This has required a range of work from novel science to developing monitoring indicators and survey methods. It also seeks efficiency savings through, practical integration of survey time on vessels, and access to new data e.g., satellites.

Our approach uses risk to inform resource allocation by utilising human activities data and the interactions with biodiversity to create risk models and determine survey priorities. This is achieved by engaging scientists and policy makers to develop monitoring options for different biodiversity components (i.e., benthic habitats, cetaceans, seals, seabirds, fish, cephalopods and plankton). This process will allow policy makers to successfully conclude on the level of resourcing required for marine monitoring, that reflects the risk to biodiversity and the public’s concerns for the marine environment, and fulfils our national and international legislative obligations.
Antioxidant enzyme cycling over reproductive lunar cycles in Pocillopora damicornis
Authors: Murphy James WA , Collier Abby C , Richmond Robert H
Published: March 2018

The impacts of continued degradation of watersheds on coastal coral reefs world-wide is alarming. Action addressing anthropogenic stressors and subsequent rehabilitation of watersheds and adjacent reefs is an urgent priority. The aim of this study is to develop and improve the use of antioxidant enzymes as biomarkers in coral species. In order to fully develop such tools, it is necessary to perform sampling of coral tissues over reproductive cycles to determine variations from baseline. By developing a greater understanding of biochemical markers of stress in corals, specifically antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), we have provided molecular tools that identify thresholds of stress on coral reefs. Our results suggest that the coral reproductive state is a significant factor affecting the activity of antioxidant enzymes. Specifically, CAT (65.92 mmol/min/mg protein, p = 0.0177) and GR (12.64 nmol/min/mg protein, p < 0.0001) display maximum activity during peak reproductive state. Whereas significant maximal SOD (154.92 nmol/min/mg protein, p < 0.0454) and Se-independent GPx (5.35 nmol/min/mg protein, p = 0.0001) activity was measured during off-peak reproductive cycles. Such insight into the cyclical variation of the activity of these enzymes should be applied towards differentiating the influence of natural biological activity cycling in diagnostic tests identifying the effects of different physical environmental factors and chemical pollutants on coral health. Through the development and application of these molecular biomarkers of stress, we look to improve our ability to identify problems at the sub-lethal level, when action can be taken to mitigate a/biotic impacts.
Incidental catch of the rare shortbill spearfish (Tetrapturus angustirostris) by the tuna purse seine fleet in the eastern tropical Pacific Ocean
Authors: Marín-Enríquez Emigdio , Muhlia-Melo Arturo
Published: March 2018

The shortbill spearfish (Tetrapturus angustirostris) is a rare, large pelagic fish that inhabits the tropical and temperate waters of the Pacific and Indian Oceans, and it is seldom incidentally captured by the purse seine and longline tuna fleets. It is listed on the International Union for the Conservation of Nature red list as data deficient, with the population likely decreasing. The main objective of this paper is to contribute basic knowledge of the species catch rate, spatial distribution, temporal trends, and association with different types of fishing sets. A 23-year (1993–2015) database of incidental catches was analyzed; data was gathered by the observers from the Inter-American Tropical Tuna Commission aboard vessels from the international tuna purse seine fleet in the eastern tropical Pacific Ocean. We also analyzed time series of sea surface temperature (SST) from different Niño regions, and 2 climatic indices, the Oceanic Niño Index (ONI) and the Pacific Decadal Oscillation (PDO). The database included information from a total of 422,970 sets; of these, ~1% resulted in a catch of 687 spearfish. Most incidental catches occurred in waters close to the equator (10ºS to 10°N), with no apparent seasonal distribution pattern. Time-series analyses showed a significant positive trend in incidental catch (~4% per year). Weak negative correlations of incidental catches with El Niño SST and ONI suggest that spearfish prefer cool waters in zones near the Equator. The PDO seemed to be more important to spearfish than El Niño events, and it is likely playing an important role in the positive trend of incidental catches. Most spearfish catches were associated with sets made on floating objects, mainly south of the equator and west of 100ºW, highlighting the oceanic behavior of this species.
Effects of seasonal and interannual events on satellite-derived phytoplankton biomass and production in the southernmost part of the California Current System during 2003–2016
Authors: Ortiz-Ahumada José Carlos , Álvarez-Borrego Saúl , Gómez-Valdés Jose
Published: March 2018

We characterized the spatial and temporal variations of sea surface temperature (SST), satellite-derived chlorophyll a (Chlsat) con-centration, and phytoplankton production (PP) along two 300-km long transects in the southernmost part of the California Current System, one off Cabo San Lázaro (TCSLa) and the other off Cabo San Lucas (TCSLu). Moderate Resolution Imaging Spectroradiometer (Aqua-MODIS) SST and Chlsat monthly composites and PP monthly composites were used for the 2003–2016 period. An “average year” was generated for each transect and each variable, as an approximation to the climatology. The Chlsat and PP values were higher in the inshore area than in the offshore area: 4.0 mg·m–3 and 4.5 g C·m–2·d–1, respectively, for the inshore area of TCSLa and 1.4 mg·m–3 and 1.8 g C·m–2·d–1, respectively, for the inshore area of TCSLu; ~0.1 mg·m–3 and 0.4 g C·m–2·d–1, respectively, for the offshore area of both transects. In general, SST showed minimum values (~17.0 ºC) in the inshore area and maximum values (~29.4 ºC) in the offshore area. Chlsat values in the coastal zone were higher on TCSLa than on TCSLu, but offshore Chlsat values were often higher on TCSLu than on TCSLa. Seasonal and interannual variations were observed on both transects, but the seasonal variations were dominant. The effects of “the Blob” in 2014 and of the 2015–2016 eastern Pacific type of El Niño were similarly strong off both capes but caused no collapse in phytoplankton biomass, which decreased to only approximately half the values for the non-El Niño years. The 2003 and 2010 central Pacific type of El Niño events also had strong impacts. The 2005 central Pacific type of El Niño had a strong impact on the biology of TCSLu, like the impact of the 2014 and 2015–2016 events, but not on the biology of TCSLa. The coastal dynamics in the California Current System show spatial variations; thus, seasonal and interannual events have different effects at different geographic locations.
High genetic diversity and limited genetic connectivity in 2 populations of an endemic and endangered coral species: Porites sverdrupi
Authors: Martínez-Castillo Violeta , Reyes-Bonilla Héctor , Rocha-Olivares Axayácatl
Published: March 2018

The coral Porites sverdrupi is the only scleractinian endemic to the Gulf of California. Over the last 2 decades its populations have been restricted to 3 areas, La Paz Bay, Loreto Bay, and Concepción Bay. As this species faces a high risk of extinction, there is an urgent need for biological, ecological, and genetic information for the guidance of conservation efforts. This is the first study on genetic diversity and connectivity in the species. For this, we analyzed coral colonies from Loreto Bay and Concepción Bay. Our results show that there is high genetic diversity in P. sverdrupi at both sites, with significant genetic structure between them. This condition is caused by a combination of short pelagic larval duration, low dispersal potential between the populations, and local adaptation. Our results emphasize the need for more research in order to establish adequate conservation strategies.
Modeling Study of the Geospace System Response to the Solar Wind Dynamic Pressure Enhancement on 17 March 2015
Authors: Ozturk D. S. , Zou S. , Ridley A. J. , Slavin J. A.
Published: March 2018

The global magnetosphere‐ionosphere‐thermosphere system is intrinsically coupled and susceptible to external drivers such as solar wind dynamic pressure enhancements. In order to understand the large‐scale dynamic processes in the magnetosphere‐ionosphere‐thermosphere system due to the compression from the solar wind, the 17 March 2015 sudden commencement was studied in detail using global numerical models. This storm was one of the most geoeffective events of the solar cycle 24 with a minimum Dst of −222 nT. The Wind spacecraft recorded a 10‐nPa increment in the solar wind dynamic pressure, while the interplanetary magnetic field BZ became further northward. The University of Michigan Block‐Adaptive‐Tree Solar wind Roe‐type Upwind Scheme global magnetohydrodynamic code was utilized to study the generation and propagation of perturbations associated with the compression of the magnetosphere system. In addition, the high‐resolution electric potential and auroral power output from the magnetohydrodynamic model was used to drive the global ionosphere‐thermosphere model to investigate the ionosphere‐thermosphere system response to pressure enhancement. During the compression, the electric potentials and convection patterns in the polar ionosphere were significantly altered when the preliminary impulse and main impulse field‐aligned currents moved from dayside to nightside. As a result of enhanced frictional heating, plasma and neutral temperatures increased at the locations where the flow speeds were enhanced, whereas the electron density dropped at these locations. In particular, the region between the preliminary impulse and main impulse field‐aligned currents experienced the most significant heating with 1000‐K ion temperature increase and 20‐K neutral temperature increase within 2 min. Comparison of the simulation results with the Poker Flat Incoherent Scatter Radar observations showed reasonable agreements despite underestimated magnitudes.
The Response of the Ocean Thermal Skin Layer to Variations in Incident Infrared Radiation
Authors: Wong Elizabeth W. , Minnett Peter J.
Published: March 2018

Ocean warming trends are observed and coincide with the increase in concentrations of greenhouse gases in the atmosphere resulting from human activities. At the ocean surface, most of the incoming infrared (IR) radiation is absorbed within the top micrometers of the ocean's surface where the thermal skin layer (TSL) exists. Thus, the incident IR radiation does not directly heat the upper few meters of the ocean. This paper investigates the physical mechanism between the absorption of IR radiation and its effect on heat transfer at the air‐sea boundary. The hypothesis is that given the heat lost through the air‐sea interface is controlled by the TSL, the TSL adjusts in response to variations in incident IR radiation to maintain the surface heat loss. This modulates the flow of heat from below and hence controls upper ocean heat content. This hypothesis is tested using the increase in incoming longwave radiation from clouds and analyzing vertical temperature profiles in the TSL retrieved from sea‐surface emission spectra. The additional energy from the absorption of increasing IR radiation adjusts the curvature of the TSL such that the upward conduction of heat from the bulk of the ocean into the TSL is reduced. The additional energy absorbed within the TSL supports more of the surface heat loss. Thus, more heat beneath the TSL is retained leading to the observed increase in upper ocean heat content.
Reconstruction of Snow on Arctic Sea Ice
Authors: Blanchard‐Wrigglesworth E. , Webster M. A. , Farrell S. L. , Bitz C. M.
Published: March 2018

Snow on Arctic sea ice is a poorly observed variable that plays an important role in the Arctic climate system and impacts the remote sensing systems that monitor Arctic sea ice. We present and validate a reconstruction of Arctic snow depth based on observed sea ice motion and snowfall derived from reanalysis data. Overall, the reconstruction is in good agreement with direct measurements of snow depth from Operation IceBridge, slightly underestimating mean IceBridge snow depth. At the local scale (10 km), the reconstruction is more skilled than a weighted climatology over first year ice, but underestimates deeper snow over multi‐year ice. Reconstructions of single buoy snow depths are unskilled, but the reconstruction shows skill in simulating the mean snow depth across all buoys. Spring snow depths show a low‐to‐high cross‐Arctic gradient and tend to be greatest in the Atlantic sector of the eastern Arctic. The relationship between ice type (multiyear or first‐year ice) and snow depth previously documented in the western Arctic is not evident in the eastern Arctic. Using ice type to weight snow depths for satellite ice thickness retrievals may not be justifiable in the eastern Arctic. Reconstructed snow depth across the Arctic shows significant interannual variability, suggesting that use of a fixed snow depth climatology may lead to biases in retrieved ice thickness and its variability. However, interannual variability in pan‐Arctic mean snow depth is comparable or smaller than the uncertainty in both the reconstruction and IceBridge, highlighting the need for high accuracy snow depth products and reconstructions.
Profiling Floats in SOCCOM: Technical Capabilities for Studying the Southern Ocean
Authors: Riser Stephen C. , Swift Dana , Drucker Robert
Published: March 2018

We report on profiling float technology used in the Southern Ocean Carbon and Climate Observations and Models (SOCCOM) program, a 6 year study of the interaction of ocean physics and the carbon cycle in the Southern Ocean. A central part of this program is to produce and deploy 200 profiling floats equipped with CTD units and chemical sensors capable of measuring dissolved oxygen, nitrate, pH, chlorophyll fluorescence, and particulate backscatter. The performance of the first 63 floats deployed in SOCCOM is examined, and examples of the design criteria used in producing these floats are shown. Some of the sensors require surface measurements to be made in the dark at regular intervals, and the probability of ascending to the sea surface in the dark is estimated as a function of year‐day and latitude. An energy budget derived from laboratory measurements shows that only about 25% of the total energy stored in the batteries is used by the biogeochemical sensors, which bodes well for the long‐term survivability of the floats. The ice‐avoidance algorithm is discussed in detail, and it is shown that it is working as designed and allowing unprecedented numbers of profiles to be collected beneath the wintertime ice cover. The overall reliability of the first group of SOCCOM floats is compared with a much larger ensemble of Argo floats; the results show that the SOCCOM floats are surviving at a rate similar to the Argo floats, which have been shown to have lifetimes in excess of 5 years.
Effects of Wind Straining on Estuarine Stratification: A Combined Observational and Modeling Study
Authors: Xie Xiaohui , Li Ming
Published: March 2018

A combined observational and numerical modeling study was conducted to clarify the effects of wind straining on estuarine stratification. Long‐term mooring observations in the middle of Chesapeake Bay showed an asymmetric stratification response to along‐channel winds. The stratification decreased under up‐estuary winds. Under down‐estuary winds, however, the stratification increased at moderate wind speeds but decreased at high wind speeds. In concert with numerical modeling, the mooring and ship‐based survey data were analyzed to test the wind‐straining mechanisms. In the middle and upper parts of the estuary, the straining of the density field by the vertical shear of the along‐channel current dominates the stratification response, enhancing stratification under the down‐estuary winds but reducing it under the up‐estuary winds. A regime diagram was constructed to place the wind‐induced stratification change in terms of the dimensionless Wedderburn number W: it is a linearly function of W for W > 0 (up‐estuary winds) but a parabolic function of W for W < 0 (down‐estuary winds). In the lower part of the estuary, however, the stratification response to the wind direction was opposite to that in the middle and upper Bay. The wind‐driven lateral circulation was much stronger there, and the cross‐channel straining of the density field by the vertical shear in the lateral currents drove the stratification response in the lower Bay. Therefore, both the along‐channel and cross‐channel straining regulate the estuarine stratification, and the net stratification change over a wind event is determined by the relative strength of along‐channel and cross‐channel straining.
Impact of Assimilation of Sea‐Ice Surface Temperatures on a Coupled Ocean and Sea‐Ice Model
Authors: Rasmussen Till A. S. , Høyer Jacob L. , Ghent Darren , Bulgin Claire E. , Dybkjær Gorm , Ribergaard Mads H. , Nielsen‐Englyst Pia , Madsen Kristine S.
Published: March 2018

We establish a methodology for assimilating satellite observations of ice surface temperature (IST) into a coupled ocean and sea‐ice model. The method corrects the 2 m air temperature based on the difference between the modeled and the observed IST. Thus the correction includes biases in the surface forcing and the ability of the model to convert incoming parameters at the surface to a net heat flux. A multisensor, daily, gap‐free surface temperature analysis has been constructed over the Arctic region. This study revealed challenges estimating the ground truth based on buoys measuring IST, as the quality of the measurement varied from buoy to buoy. With these precautions we find a cold temperature bias in the remotely sensed data, and a warm bias in the modeled data relative to ice mounted buoy temperatures, prior to assimilation. As a consequence, this study weighted the modeled IST and the observed IST equally in the correction. The impact of IST was determined for experiments with and without the assimilation of IST and sea‐ice concentration. We find that assimilation of remotely sensed data results in a cooling of IST, which improves the timing of the snow melt onset. The improved snow cover in spring is only based on observations from one buoy, thus additional good quality observations could strengthen the conclusions. The ice cover and the sea‐ice thickness are increased, primarily in the experiment without sea‐ice concentration assimilation.
Detection of Ice Wedge Cracking in Permafrost Using Miniature Accelerometers
Authors: O'Neill H. Brendan , Christiansen Hanne H.
Published: March 2018

Determining the exact timing of ice wedge cracking in permafrost is challenging. Five miniature accelerometers were installed near the ground surface in the trough of a primary ice wedge within a network of low‐centered polygons in Adventdalen, Svalbard, to test whether these instruments could be used to detect dynamics of thermal contraction cracking. Data from 2003 to 2013 were analyzed to characterize cryoseismic signals in the ice wedge trough. High‐magnitude accelerations (from 5 g to at least 100 g) were typically registered in late winter, when the top of permafrost had cooled to about −10°C; these likely correspond to ice wedge cracking in permafrost. Tensile stresses calculated from temperatures measured in the ice wedge trough are near laboratory strengths reported for ice and mineral active layer sediments, supporting the interpretation that large accelerations are caused by thermal contraction cracking. Lower magnitude accelerations occurred throughout the freezing season, usually coinciding with rapid cooling at the ground surface. These small accelerations may be associated with (i) the initiation of small cracks in the active layer of the trough or (ii) the horizontal and vertical propagation of existing ice wedge cracks. The results of this investigation indicate that miniature accelerometers are an effective, inexpensive, and simple method to determine the timing of ice wedge cracking and rates of crack propagation along ice wedge troughs.
The Response Time of Glacial Erosion
Authors: Herman Frédéric , Braun Jean , Deal Eric , Prasicek Günther
Published: March 2018

There has been recent progress in the understanding of the evolution of Quaternary climate. Simultaneously, there have been improvements in the understanding of glacial erosion processes, with better parameter constraints. Despite this, there remains much debate about whether or not the observed cooling over the Quaternary has driven an increase in glacial erosion rates. Most studies agree that the erosional response to climate change must be transient; therefore, the time scale of the climatic change and the response time of glacial erosion must be accounted for. Here we analyze the equations governing glacial erosion in a steadily uplifting landscape with variable climatic forcing and derive expressions for two fundamental response time scales. The first time scale describes the response of the glacier and the second one the glacial erosion response. We find that glaciers have characteristic time scales of the order of 10 to 10,000 years, while the characteristic time scale for glacial erosion is of the order of a few tens of thousands to a few million years. We then use a numerical model to validate the approximations made to derive the analytical solutions. The solutions show that short period forcing is dampened by the glacier response time, and long period forcing (>1 Myr) may be dampened by erosional response of glaciers when the rock uplift rates are high. In most tectonic and climatic conditions, we expect to see the strongest response of glacial erosion to periodic climatic forcing corresponding to Plio‐Pleistocene climatic cycles. Finally, we use the numerical model to predict the response of glacial systems to the observed climatic forcing of the Quaternary, including, but not limited to, the Milankovich periods and the long‐term secular cooling trend. We conclude that an increase of glacial erosion in response to Quaternary cooling is physically plausible, and we show that the magnitude of the increase depends on rock uplift and ice accumulation rates.
Microporous Hydroxyapatite Ceramic Composites as Tissue Engineering Scaffolds: An Experimental and Computational Study
Authors: Kanhed Satish , Awasthi Shikha , Midha Swati , Nair Jitin , Nisar Ambreen , Patel Anup Kumar , Pandey Aditi , Sharma Rajeev , Goel Sneha , Upadhyaya Anish , Ghosh Sourabh , Balani Kantesh
Published: March 2018

Bone‐tissue engineering mandates the development of multi‐functional bioactive porous hydroxyapatite (HAp) scaffolds. Herein, microwave sintered HAp/ZnO and HAp/Ag composite scaffolds with ≈5–19% porosity are developed using 0–30 vol% graphite as a porogen. The mechanical properties of the porous scaffold are analyzed in detail, revealing that even being more porous, the reinforcement of ZnO (9% porosity, hardness of 2.8 GPa, and toughness of 3.5 MPa.m1/2) has shown to have better hardness and fracture toughness when compared to Ag (5% porosity, hardness of 1.6 GPa, and toughness of 2.6 MPa.m1/2). The flexural strength obtained experimentally are complemented with a finite‐element technique that adopts microstructural features in visualizing the effect of porosity on stress distribution. The antibacterial efficacy and cytocompatibility of these composites are validated by increased metabolic activity and conspicuous cell‐matrix interactions. The anticipation of the results reveal that HAp/ZnO (9% porosity) and HAp/Ag (5% porosity) composites can be used as a potential multi‐functional bone implant scaffolds.
Developing High‐Performance Lithium Metal Anode in Liquid Electrolytes: Challenges and Progress
Authors: Li Sa , Jiang Mengwen , Xie Yong , Xu Hui , Jia Junyao , Li Ju
Published: March 2018

Lithium metal anodes are potentially key for next‐generation energy‐dense batteries because of the extremely high capacity and the ultralow redox potential. However, notorious safety concerns of Li metal in liquid electrolytes have significantly retarded its commercialization: on one hand, lithium metal morphological instabilities (LMI) can cause cell shorting and even explosion; on the other hand, breaking of the grown Li arms induces the so‐called “dead Li”; furthermore, the continuous consumption of the liquid electrolyte and cycleable lithium also shortens cell life. The research community has been seeking new strategies to protect Li metal anodes and significant progress has been made in the last decade. Here, an overview of the fundamental understandings of solid electrolyte interphase (SEI) formation, conceptual models, and advanced real‐time characterizations of LMI are presented. Instructed by the conceptual models, strategies including increasing the donatable fluorine concentration (DFC) in liquid to enrich LiF component in SEI, increasing salt concentration (ionic strength) and sacrificial electrolyte additives, building artificial SEI to boost self‐healing of natural SEI, and 3D electrode frameworks to reduce current density and delay Sand's extinction are summarized. Practical challenges in competing with graphite and silicon anodes are outlined.
Reliable Synthesis of Large‐Area Monolayer WS2 Single Crystals, Films, and Heterostructures with Extraordinary Photoluminescence Induced by Water Intercalation
Authors: Zhang Qianhui , Lu Jianfeng , Wang Ziyu , Dai Zhigao , Zhang Yupeng , Huang Fuzhi , Bao Qiaoliang , Duan Wenhui , Fuhrer Michael S. , Zheng Changxi
Published: March 2018

Two‐dimensional transition metal dichalcogenides (TMDs) hold great potential for future low‐energy optoelectronics owing to their unique electronic, optical, and mechanical properties. Chemical vapor deposition (CVD) is the technique widely used for the synthesis of large‐area TMDs. However, due to high sensitivity to the growth environment, reliable synthesis of monolayer TMDs via CVD remains challenging. Here a controllable CVD process is developed for large‐area synthesis of monolayer WS2 crystals, films, and in‐plane graphene–WS2 heterostructures by cleaning the reaction tube with hydrochloric acid, sulfuric acid, and aqua regia. The concise cleaning process can remove the residual contaminates attached to the CVD reaction tube and crucibles, reducing the nucleation density but enhancing the diffusion length of WS2 species. The photoluminescence (PL) mappings of a WS2 single crystal and film reveal that the extraordinary PL around the edges of a triangular single crystal is induced by ambient water intercalation at the WS2–sapphire interface. The extraordinary PL can be controlled by the choice of substrates with different wettabilities.
Effect of Si3N4‐Mediated Inversion Layer on the Electroluminescence Properties of Silicon Nanocrystal Superlattices
Authors: López‐Vidrier Julian , Gutsch Sebastian , Blázquez Oriol , Valenta Jan , Hiller Daniel , Laube Jan , Blanco‐Portals Javier , López‐Conesa Lluís , Estradé Sònia , Peiró Francesca , Garrido Blas , Hernández Sergi , Zacharias Margit
Published: March 2018

The achievement of an efficient all‐Si electrically‐pumped light emitter is a major milestone in present optoelectronics still to be fulfilled. Silicon nanocrystals (Si NCs) are an attractive material which, by means of the quantum confinement effect, allow attaining engineered bandgap visible emission from Si by controlling the NC size. In this work, SiO2‐embedded Si NCs are employed as an active layer within a light‐emitting device structure. It is demonstrated that the use of an additional thin Si3N4 interlayer within the metal–insulator–semiconductor device design induces an enhanced minority carrier injection from the substrate, which in turn increases the efficiency of sequential carrier injection under pulsed electrical excitation. This results in a substantial increase in the electroluminescence efficiency of the device. Here, the effect of this Si3N4 interlayer on the structural, optical, electrical, and electro‐optical properties of a Si NC‐based light emitter is reported, and the physics underlying these results is discussed.
Hohe elektromagnetische Feldverstärkung in nanotubularen TiO2‐Elektroden
Authors: Öner Ibrahim Halil , Querebillo Christine Joy , David Christin , Gernert Ulrich , Walter Carsten , Driess Matthias , Leimkühler Silke , Ly Khoa Hoang , Weidinger Inez M.
Published: March 2018

Wir präsentieren die Herstellung von TiO2‐Nanoröhren‐Elektroden mit hoher Biokompatibilität und außergewöhnlichen spektroskopischen Eigenschaften. Intensive oberflächenverstärkte Resonanz‐Raman‐Signale der Häm‐Gruppe des kovalent an die Elektrodenoberfläche immobilisierten Redox‐Enzyms Cytochrom b5 wurden beobachtet, die auf konservierte Proteinstruktur und Redox‐Eigenschaften schließen lassen. Der Verstärkungsfaktor konnte selektiv über die Kalzinierungstemperatur kontrolliert werden, wobei ein Rekordwert von über 70 bei einer Temperatur von 475 °C gefunden wurde. Zum ersten Mal konnten damit solche hohen Werte für eine nicht direkt oberflächengebundene Probe erreicht werden, bei der chemische Verstärkungseffekte ausgeschlossen werden können. Damit sind die hohen Verstärkungsfaktoren ausschließlich auf lokalisierte elektrische Felder zurückzuführen, hervorgerufen durch die spezifischen optischen Eigenschaften der nanotubularen Geometrie der Elektroden.
Monitoring social behaviour as an assessment of translocation success in a reintroduced population of the endangered Leon Springs pupfish (Cyprinodon bovinus)
Authors: Al‐Shaer Layla , Bloch Andrew , Little Kimberly , Itzkowitz M.
Published: March 2018

Translocation of endangered species from captivity into the wild is a common conservation practice used to bolster populations, expand natural ranges, and restore species that have been extirpated.

Often little is known of the fate of organisms after they are released, and extended monitoring of reintroduced populations is necessary for understanding the efficacy of this method.

Thought to have become extinct, the endangered Leon Springs pupfish (Cyprinodon bovinus) was rediscovered in 1965. Recently, conservation efforts have focused on renovating their natural habitat and reintroducing C. bovinus from a captive colony established in 1976 back into the ancestral habitat.

A reintroduction was performed in 2015, and the population was monitored over the next 14 months to ascertain whether territorial males were behaving typically for the species, and whether there were any changes in social behaviour over time.

An established population in nearby Diamond Y Spring was used as a benchmark for typical social behaviour, and as an indicator for any expected seasonal differences in behaviour.

The development of a typical social system at Monsanto Deep Pool was evident almost immediately, as males started to establish breeding territories, defend them from intruders, and participate in reproductive activities, such as courtship and spawning. The presence of juveniles within a year indicated that individuals were successfully reproducing.

It appears that the translocated C. bovinus are developing into a stable and reproductively successful population.
Expedient Construction of the Hexacycle of Franchetine
Authors: Lv Zhengchao , Gao Lingzhi , Cheng Chuanxu , Niu Wei , Wang Jian‐Li , Xu Liang
Published: March 2018

Franchetine, a unique 7,17‐seco type of norditerpenoid alkaloid, possesses a highly congested polycyclic architecture coupled with nine stereogenic centers. Here we present an efficient synthetic approach for the intact hexacyclic framework of franchetine from the known tricyle 16 in 20 steps. The synthesis features a diastereoselective 6‐exo‐tet radical cyclization for construction of ring A and a unique oxidative Wagner–Meerwein‐type rearrangement to realize the functionalized [3.2.1] bridging ring CD.
Active Disturbance Rejection Control for Teleoperation Systems with Actuator Saturation
Authors: Zhao Ling , Liu Lei , Wang Yingjie , Yang Hongjiu
Published: March 2018

In this paper, stabilization of a nonlinear bilateral teleoperation system with time delays and actuator saturation is investigated via active disturbance rejection control (ADRC). An linear extended state observer is introduced to deal with the lumped system uncertainties. Lyapunov functions are given to prove the stabilization of the closed‐loop bilateral teleoperation system. Two Phantom Premium 1.5 HighForce (HF) robot manipulators are used in experiments to demonstrate the effectiveness of the proposed method in this paper.
A GIS‐based spatial index of feedstock‐mixture availability for anaerobic co‐digestion of Mediterranean by‐products and agricultural residues
Authors: Valenti Francesca , Liao Wei , Porto Simona MC
Published: March 2018

Biogas obtained from the anaerobic digestion of biomasses has increasingly been considered a feasible alternative to energy production from fossil fuel because of the possible advantages derived from both the reduction of the environmental burden and the reuse of by‐products and agricultural residues. Italy is the third largest biogas producer in the world after China and Germany, but the biogas sector in southern Italy, especially in Sicily, is still developing.

The objective of this study was to contribute to the sustainable development of the biogas sector in Sicily by developing a method for the localization of geographical areas suitable for biogas production. First, a feedstock mixture found in previous research studies (which investigated several mixes of main agricultural residues and by‐products available in Sicily for the enhancement of biogas production in terms of methane content) was used to evaluate each feedstock territorial distribution in a study area. Then a GIS‐based model for the computation of a spatial index of feedstock‐mixture availability, ifm_a , was developed. The computed spatial index was applied on a GIS map to investigate the availability of the feedstock mixture in the area under study.

The results of the territorial analyses obtained by applying the index showed the geographical areas suitable for the development of new biogas plants. The results of this study could be helpful in reducing the significant transport costs of each feedstock as well as the environmental impact of biogas production. In this regard, the results are in line with the policy priorities of the Europe 2020 strategy, which aims to valorize by‐products and agricultural residues through their reuse. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd
Production of 1,3‐butadiene and ε‐caprolactam from C6 sugars: Techno‐economic analysis
Authors: Moncada Jonathan , Gursel Iris Vural , Worrell Ernst , Ramírez Andrea
Published: March 2018

This study assesses the techno‐economic performance of production lines for obtaining 1,3‐butadiene and ε‐caprolactam from C6 sugars. Process models were developed to assess their technical performance and to derive inputs for economic analysis. The economic assessment was carried out using net present value (NPV) and production costs as indicators. Sensitivity analyses were carried out to account for the effects of variations in inputs, such as processing capacity, valorization of humins, and prices, on the economic outputs. Results indicate that both production lines perform similarly from an energy intensity point of view (34–50 MJ/kg of main product). However, in terms of yield (kg of product per kg C6 sugar), caprolactam shows higher values by a factor of 1.6–3.6 in comparison to that of butadiene. The butadiene production line is not economically attractive, showing a negative NPV (−647 to −642 M€) and production costs 3–5 times higher than the reference market price (Case I 4369 €/tonne, Case II 3406 €/tonne). The caprolactam production line seems to be unfeasible with negative NPV (−229 M€) and production costs 30% higher than the reference price (Case III 2595 €/tonne, Case IV 1875 €/tonne). However, if the production yield is increased, the caprolactam production line becomes economically attractive with production costs 6% lower than its reference market price. The production costs of caprolactam can be further decreased if the process capacity is increased, reflecting the benefits of the economies of scale, as well as including heat and power produced from humins. Overall, the caprolactam production line shows higher economic potential. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd
Thermodynamics of the pseudo‐knot in helix 18 of 16S ribosomal RNA
Authors: Wojciechowska Monika , Dudek Marta , Trylska Joanna
Published: March 2018

A fragment of E. coli 16S rRNA formed by nucleotides 500 to 545 is termed helix 18. Nucleotides 505‐507 and 524‐526 form a pseudo‐knot and its distortion affects ribosome function. Helix 18 isolated from the ribosome context is thus an interesting fragment to investigate the structural properties and folding of RNA with pseudo‐knots. With all‐atom molecular dynamics simulations, spectroscopic and gel electrophoresis experiments, we investigated thermodynamics of helix 18, with a focus on its pseudo‐knot. In solution studies at ambient conditions we observed dimerization of helix 18. We proposed that the loop, containing nucleotides forming the pseudo‐knot, interacts with another monomer of helix 18. The native dimer is difficult to break but introducing mutations in the pseudo‐knot indeed assured a monomeric form of helix 18. Molecular dynamics simulations at 310 K confirmed the stability of the pseudo‐knot but at elevated temperatures this pseudo‐knot was the first part of helix 18 to lose the hydrogen bond pattern. To further determine helix 18 stability, we analyzed the interactions of helix 18 with short oligomers complementary to a nucleotide stretch containing the pseudo‐knot. The formation of higher‐order structures by helix 18 impacts hybridization efficiency of peptide nucleic acid and 2'‐O methyl RNA oligomers.
Living a meaningful life with chronic pain – further follow‐up
Authors: Dysvik Elin , Furnes Bodil
Published: March 2018

Key Clinical Message

Living a meaningful life with chronic pain seems to depend on the patient having the leading role in their own life. Adequate assistance from healthcare professionals should be balanced during changing circumstances. Successful follow‐up demands an independent biopsychosocial–spiritual–existential perspective, where patient‐centered care and a focus on resilience go together.
Optimization of Ellagic Acid Purification from Pomegranate Husk by Antisolvent Recrystallization
Authors: Wang Li , Lian Bolin , Wu Weiwei , Deng Yiping , Liu Yanjie , Wang Lingling , Li Yuanyuan , Wang Zijian , Zhao Xiuhua
Published: March 2018

Ellagic acid (EA) was produced from pomegranate husk by extraction of tannins followed by acid hydrolysis and purified by antisolvent recrystallization. Response surface methodology, based on a five‐level, four‐variable central composite design, was employed to find the optimum purification conditions. Under these conditions, high purity and yield of EA was obtained in close agreement with the predicted values by the model. Analyzes of surface morphology and in vitro percutaneous absorption experiments of EA let conclude that the granule morphology of the purified EA was significantly different from the crude EA, and its particle size was much smaller than that of the crude EA. Evaluation in vitro demonstrated that the permeation rate of the purified EA was higher compared with the crude EA.
Poly(vinylidene fluoride)‐Based Membranes for Microalgae Filtration
Authors: Marbelia Lisendra , Bilad Muhammad R. , Maes Sarah , Arafat Hassan A. , Vankelecom Ivo F. J.
Published: March 2018

Two poly(vinylidene fluoride) (PVDF) membrane modification approaches, i.e., poly(vinylpyrrolidone) (PVP) modification and sulfonation, were applied and investigated to produce a fouling‐resistant membrane for microalgae filtration. Both methods were able to alter the membrane surface to become more hydrophilic. However, clean water permeance increased only for the PVP‐modified membranes, while the sulfonated membranes underwent a significant morphology transformation to a denser membrane and thus lower permeance. Microalgae filtration with PVP‐modified membranes showed less fouling compared to the pristine one, particularly in the beginning of the filtration, indicating that fouling reduction on these membranes mainly occurs in the initial fouling stage. Fouling is also found to be influenced by the microalgae species, possibly due to the different properties of the formed cake layer.
Adhesion Moment of a Particle on a Wall in Gaseous Environment
Authors: Haarmann Alexander , Schmidt Eberhard
Published: March 2018

If a particle adheres to a wall, it gets flattened. When such a particle gets stressed sideways by an external force, it will start to roll. To get the particle into a rolling motion, a resistive moment must be overcome, the so‐called adhesion moment. An experimental setup was designed to measure the force which must be applied to an adhered particle to trigger a rolling motion in the specimen chamber of an environmental scanning electron microscope (ESEM). From this force, the adhesion moment can be calculated. A detailed explanation of the experiments will be given. The results of the experiments are discussed.
Hydrogen Bonding Effects on the Reversible Reorganization of Organic Films Electrografted on Glassy Carbon Electrodes
Authors: Morales‐Martínez Daniel , González Felipe J.
Published: March 2018

The electrochemical oxidation of tetrabutylammonium carboxylates derived from 6‐oxoheptanoic acid and 6‐heptynoic acid was performed on glassy carbon electrodes to generate covalently modified electrodes bearing alkyl‐ketone and alkynyl groups. These surfaces were used as models of hydrogen‐bond‐accepting surfaces to study the interaction of water with the grafted film; 1,4‐benzoquinone was used as the redox probe to demonstrate the existence of these interactions. The voltammetric behavior of this redox probe on the modified electrode changed during cycling. However, leaving this electrode to stand in the electrolyte solution allows the recovery of the starting voltammogram. These changes observed between cycling and stand time are cyclical and can be explained through a reversible reorganization effect of the grafted film, which is attributed to hydrogen bonding interactions between the functional groups present in the structure film and water present in the solvent. Supporting these surface effects, the switching behavior was absent on hydrophobic films formed with saturated aliphatic chains or by using ferrocene as non‐hydrogen bonding redox probe.
On the Antibacterial Activity of Azacarboxylate Ligands: Lowered Metal Ion Affinities for Bis‐amide Derivatives of EDTA do not mean Reduced Activity
Authors: Mulla Raminder S. , Beecroft Marikka S. , Pal Robert , Aguilar Juan A. , Pitarch‐Jarque Javier , García‐España Enrique , Lurie‐Luke Elena , Sharples Gary J. , Gareth Williams J. A.
Published: March 2018

EDTA is widely used as an inhibitor of bacterial growth, affecting the uptake and control of metal ions by microorganisms. We describe the synthesis and characterisation of two symmetrical bis‐amide derivatives of EDTA, featuring glycyl or pyridyl substituents: AmGly2 and AmPy2. Metal ion affinities (logK) have been evaluated for a range of metals (Mg2+, Ca2+, Fe3+, Mn2+, Zn2+), revealing less avid binding compared to EDTA. The solid‐state structures of AmGly2 and of its Mg2+ complex have been determined crystallographically. The latter shows an unusual 7‐coordinate, capped octahedral Mg2+ centre. The antibacterial activities of the two ligands and of EDTA have been evaluated against a range of health‐relevant bacterial species, three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and a Gram positive (Staphylococcus aureus). The AmPy2 ligand is the only one that displays a significant inhibitory effect against K. pneumoniae, but is less effective against the other organisms. AmGly2 exhibits a more powerful inhibitory effect against E. coli at lower concentrations than EDTA (<3 mm) or AmPy2, but loses its efficacy at higher concentrations. The growth inhibition of EDTA and AmGly2 on mutant E. coli strains with defects in outer‐membrane lipopolysaccharide (LPS) structures has been assessed to provide insight into the unexpected behaviour. Taken together, the results contradict the assumption of a simple link between metal ion affinity and antimicrobial efficacy.
A Stereochemically Driven Supramolecular Polymerisation
Authors: Tasca Elisamaria , D'Abramo Marco , Galantini Luciano , Giuliani Anna Maria , Pavel Nicolae Viorel , Palazzo Gerardo , Giustini Mauro
Published: March 2018

Anthracyclines self‐assemble in water into dimers. In the presence of sufficiently high salt (NaCl) concentrations, solutions of the antibiotic doxorubicin, but not those of the closely related molecules daunomycin and epirubicin, turn into gels barely compatible with the presence of small oligomers. The use of spectroscopic, scattering, imaging and computational techniques, allowed light to be shed on the self‐assembly process that triggered doxorubicin gelification. A complex picture emerged, with doxorubicin molecules assembled into long, highly chiral, supramolecular aggregates made of hundreds of units, showing redshifted fluorescence spectra, very short fluorescence lifetimes and small‐angle X‐ray scattering profiles compatible with long cylinders. The involvement of specific chemical groups and the need for a specific stereochemistry of the monomers in the formation of a hydrogen‐bond network to stabilise the supramolecular aggregates was supported by molecular dynamics calculations. A salt‐induced, temperature‐dependent, cooperative nucleation–elongation supramolecular polymerisation of the doxorubicin molecules is deduced.