bluuebunny/crossref_metadata_2025 huggingface dataset:
Benthic mollusc assemblage of the Agua Dulce/El Ermitaño lagoon estuarine system, Jalisco, Mexico
Authors: Landa-Jaime V
Published: August 2017

The malacological fauna of the Agua Dulce/El Ermitaño lagoon estuarine system was characterized and its relation to some environmental parameters determined. Five samplings were carried out in January, August, October and December 1993, and February 1994. Biological, hydrological and sediment samples were taken at seven stations in each water body of the system, located on the northern coast of the state of Jalisco (Mexico). The values of some physical and chemical parameters were recorded and differences were found between both water bodies, mainly in regard to salinity, as an average value of 27 psu was obtained for Agua Dulce lagoon and of 2 psu for El Ermitaño estuary. The qualitative analysis of the sediments showed that the system is made up of four basic types: sandy silt, clayey silt, fine to medium sand and a small part of rocky substrate. The malacological fauna was composed of two classes, Gasteropoda and Bivalvia, the first being the one that presented a greater number of species; 6,782 live organisms and 18,508 dead organisms were collected, corresponding to 17 species of gastropods and 14 bivalves. Of the 31 species collected, only 9 were found alive and some appeared in both water bodies in spite of the salinity gradient recorded in the system. Groups of representative species were identified for four types of environments (marine, >25 psu; euryhaline, 10–18 psu; brackish, 5–10 psu; and freshwater, 0–5 psu). Finally, the most important species were the bivalves Tagelus longisinuatus and Mytella strigata, and the gastropods Rissoella excolpa and Bittium mexicanum, with the highest abundances of the cycle. Low diversity values were obtained (D = 1.5–1.8, Dmax = 2.5); however, they were within those recorded for tropical and subtropical coastal ecosystems.
Barotropic background currents in the Gulf of California
Authors: Makarov V , Jiménez-Illescas A
Published: August 2017

A field of barotropic background currents (BC) in the Gulf of California is constructed numerically. The definition of BC used here is based on suppositions about (i) the horizontal homogenization of potential vorticity in large-scale gyres, and (ii) the tendency of a current structure to evolve to a state with a minimum of system mechanical energy. In the barotropic case here, the numerical algorithm is reduced to the solution of the Dirichlet boundary problems for planetary, topographic and flowing integral streamfunction components separately. The results obtained are compared to observations and the results of other numerical models. The calculated barotropic BC realistically describe the main features of the circulation in the southern part of the Gulf of California, including its mouth. Cyclonic movement in the deep-water and anticyclonic movement near the coasts are observed. The numerical results for the central and northern parts of the gulf, where seasonal climatological differences are pronounced, coincide with observations in the upper layer only during the winter season; i.e., the circulation here is anticyclonic. Thus, there are reasons to suggest that mainly planetary-topographic forcing, especially in the southern part, forms the circulation in the lower layer. The seasonal variability of currents in the upper layer caused by non-stationary effects such as wind, heat flux and baroclinicity, is apparently in phase with these mechanisms during winter, and in antiphase during summer, particularly for the central and northern gulf.
Preliminary estimation of optimal sample size for assessing the recruitment of Mesodesma donacium (Lamarck, 1818) on beaches of central-north Chile: Application of the power analysis
Authors: Ortiz MA , Stotz WB
Published: August 2017

This work presents a preliminary study to estimate the optimal sample size for the assessment of recruitment of Mesodesma donacium, an important bivalve that supports an intensive fishery in the most important bays of northern Chile. The specific objective was to assess the influence of the cusps (bays and horns) on the abundance of early recruits (< 15 mm shell length) of M. donacium and to include this effect on the sampling program. The bays and horns produced a difference (noise) of ca 20% in the density estimation, which was supported by the low statistical power calculated (0.20, 0.25 and 0.30 for November, December and March, respectively). Based on these results, we suggest that the assessment of the recruitment of M. donacium requires a sampling which comprises both bays and horns in intermediate beaches of northern Chile. Based on the effect size estimated of ca 0.41 for the three study periods, 80 corers must be taken from bays as well as from horns as a preliminary sample size strategy. The a priori statistical power analysis is one of the most useful strategies for the estimation of optimum sample size when the goal is to assess any working hypothesis.
Interaction between the California sea lion and the artisanal fishery in La Paz Bay, Gulf of California, Mexico
Authors: Aurioles-Gamboa D , García-Rodríguez F , Ramírez-Rodríguez M , Hernández-Camacho C
Published: August 2017

Information about California sea lion prey and the artisanal fishery catch in the area of the Los Islotes sea lion rookery, in northeastern La Paz Bay, México, was examined to estimate potential overlap and competition between these consumers. Sea lions there consume about 435 t annually, with peak consumption in winter. The artisanal fishery captures about 730 t of bony fish annually, with an increase in summer. Based on a five-year study, sea lions preyed on 76 fish species, but in terms of relative importance (RI), 35% of these was represented by only five species, of which only one has regional commercial value. Principal fishery targets comprised 28 species in four families, representing 76.2% of the total capture. Of these, the remains of only two species appeared in sea lion scats, and of them, only the spotted sand bass, Paralabrax maculatofasciatus, has significant commercial value, but it is poorly represented as sea lion prey (< 5% RI). Despite the limited overlap with fishery target species, the Los Islotes population exhibited the highest entanglement index (7–9%) of all sea lion colonies studied in Mexico. All sex/age categories of sea lions showed similar entanglement indices, with the entangled fraction approximately proportional to the total population for three surveys in different years. The data suggest that most animals become entangled by accident. Entanglement is probably due to the combined effect of extensive gillnet deployment in the bay and overlap in the areas where sea lions feed and fishermen operate.
Microhabitat and associated biota of abalone juveniles, Haliotis fulgens and H. corrugata, in Bahía Tortugas, Baja California Sur, Mexico
Authors: Carreón-Palau L , Guzmán-del-Próo SA , Belmar-Pérez J , Carrillo-Laguna J , Herrera-Fragoso R
Published: August 2017

Abalone is an important economical resource on the west coast of Baja California. The most important species in this fishery are green and pink abalone (Haliotis fulgens and H. corrugata, respectively). Overfishing has been implicated in the decline of the Mexican abalone fishery. Among the population parameters, recruitment is a highly variable event. To obtain a better understanding of the ecology of abalone juvenile recruitment, the physical and biological characteristics of the microhabitat of juveniles of green and pink abalone were studied at Bahía Tortugas, Baja California Sur (Mexico), during autumn and spring from 1996 to 1998. Two abalone reefs with different depth, relief and wave exposure were surveyed: Clam Bay, with depths of 0.5 to 5 m, and Morro de Adentro, with depths of 6 to 12 m. Four different bottom types were recognized: (a) sheltered and low relief bottom, (b) semiexposed and moderate relief bottom, (c) exposed and high relief bottom, and (d) exposed and moderate relief bottom. Juveniles of green and pink abalone from 3 to 13 mm shell length were observed under small rocks, pebbles and flat stones no longer than 15|00E2|??20 cm, always covered with crusts of coralline algae. Several tiny juveniles of Fisurella, Stenoplax, and Crepipatella of similar sizes (5–10 mm) shared the microhabitat. Juveniles between 15 and 90 mm shell length were found under flat, rhombic or irregular-shaped rocks (20–110 mm length), most of them deployed in imbricate arrangement. Abalone juveniles shared this microhabitat with bryozoans, sponges, ascidians, chitons, and annelids. Bottoms with imbricate arrangement, low wave exposure, and the low depth of Clam Bay were favorable for the high occurrence of juveniles of H. fulgens. Juveniles of H. corrugata showed a high occurrence in exposed and deeper zones of Morro de Adentro.
Growth of the purple snail Plicopurpura pansa in Baja California Sur, Mexico
Authors: Ramírez-Rodríguez M , Naegel LCA
Published: August 2017

To study the growth of the purple snail Plicopurpura pansa at the northern limit of its distribution, from 1999 to 2001 monthly random samples were obtained from two beaches in the southern part of the Baja California Peninsula (Mexico): one on the Gulf of California and the other on the west coast of the peninsula. Mark and recapture experiments, as well as laboratory rearing were also done. The von Bertalanffy growth equation parameters derived from length frequency data were K = 0.17 and L∞ = 90 mm, and agree with those estimated from the mark and recapture data, but are lower that those reported in the literature for P. pansa from the central and southern Mexican Pacific. Snails maintained under laboratory conditions had low growth rates. These results could be used to implement models for the assessment of purple snail fisheries.
Presence, distribution and contamination levels of lead in the surface sediments of the Ria of Ferrol (NW Spain)
Authors: Prego R , Cobelo-García A , Tubío C , Barciela MC
Published: August 2017

This article discuss, using sediment samples from the Ria of Ferrol, the need for a better understanding of the biogeochemical cycle of lead in the Galician rias which, until now, was based on differing methodologies mainly applied to the biota in only few areas of the most important rias from a socio-economic point of view. Thirty-five samples of superficial sediment were analysed for lead (in the < 63 ∞m and total fractions) and opal percentage and organic carbon in the total. An analytical method is proposed employing ETAAS, whereby the sediment is introduced directly as a slurry together with the optimised amount of chemical modifiers. The accuracy of the method was checked by means of a certified reference material, obtaining a sensitivity of 2.72 ∞g g–1 Pb with an RSD of 5.9%. Values of lead in the superficial sediment of the Ria of Ferrol ranged from 13.5 to 159.1 ∞g g–1 for the fraction < 63 ∞m, and from 12.1 to 142.5 ∞g g–1 for the total fraction. The distribution does not follow a decreasing trend from the innermost part of the ria, as may have been expected, but rather the maximum values were found in the vicinity of the harbour area in the middle ria, indicating that rias behave as a lead deposition barrier avoiding the export of the metal to the open sea. Lead dispersion is mainly controlled by the tidal currents, given its lowest concentrations in the zones of strongest current, and also by the plankton, following the relationship obtained [Pb] = 48 [opal] + 16. A baseline lead concentration of 18.2 ∞g g–1 was obtained for the fraction < 63 ∞m using core samples dated at 3745 ± 70 years before present. Applying this background values, the lead enrichment in the Ria of Ferrol is classified from moderate to considerable.
Development and optimization of a digestion method for heavy metal determination in scleractinian corals by Atomic Absorption Spectrometry (AAS).
Authors: Galindo-Riaño MD , Castellón L , González K , García-Vargas M
Published: August 2017

In the last decade a great number of studies have been directed especially to the evaluation of the environmental impact of heavy metal concentration levels in coral barriers. Related to studies in scleractinian corals, many chemical techniques have been proposed to determine heavy metals but Atomic Absorption Spectrometry (AAS) is the most widely used; however, regarding sample pretreatment methods there is not a unique criterion on the requirements to obtain the precise and accurate results needed in this analysis. So, in this paper the application of several widely used pretreatment methods for digestion of corals and sediments were studied in which HNO3, HCl and HClO4 are used in different conditions (concentration, temperature, etc.), with the aim of comparing their efficiency. The method in which a combination of HNO3 and HClO4 was used resulted the most effective one. A 22 experimental design was carried out to study the influence of the HNO3 volume as well as to optimize the HNO3:HClO4 mixture. Finally the method was validated using reference certificate material (SOIL-7) using the NIST accuracy test and applying it in the analyses of different coral samples which produced results with appropriate analytical quality.
Corrosion-erosion processes of the AA 5083 (Al-Mg) alloy in seawater
Authors: Aballe A , Bethencourt M , Botana FJ , Marcos M , Sánchez-Amaya JMA
Published: August 2017

Fourier Transforms are applied to analyse surface roughness profiles recorded on samples coming from corrosion-erosion assays. The information retrieved using this method clearly complements that revealed by the more classical roughness amplitude parameters. The analysis procedure here proposed can be applied not only to characterise the surface of corroded samples but, in general, to evaluate the quality of any surface after application of finishing treatments.
Biochemical composition and energy content of the mussel Mytilus galloprovincialis of subtidal and rocky shore origin: Influence of enviromental variables and source of mussel seed
Authors: Freites L , Fernández-Reiriz MJ , Labarta U
Published: August 2017

The energy content and biochemical composition of seed of the mussel Mytilus galloprovincialis of two distinct origins (subtidal and rocky shore) were compared after both groups were transferred to the water column (subtidal habitat) in the Arousa Ria, NW Spain. The experimental period comprised a total of 228 days. The relative percentages of carbohydrates, glycogen and lipids were significantly higher in the subtidal mussels in the first 15 days, whereas the proteins were significantly higher in the rocky shore mussels during the first 36 days. A multiple regression analysis referred to the same time period showed that the origin of the mussel seed influenced significantly the variance observed in the energy values of all biochemical components (measured in terms of kJ mg–1). In the period between days 50 and 110, mussel origin only showed a significant effect on the lipid energy content, but in contrast to the previous period, the content was greater in the rocky shore mussels. The multiple regression analysis showed that after 125 days of culture, mussel origin did not influence the variance observed in the energy values of all biochemical components, whereas the ratio chlorophyll a/particulate organic material, temperature and total particulate material influenced significantly the variance observed in the different energy values of all biochemical components. Changes observed in the energy content of carbohydrates and lipids throughout the different periods of this study can be related to catabolismanabolism processes linked mainly to the availability of phytoplanktonic food. Moreover, with regard to lipids, our results suggest that changes were also associated with reproductive activity.
Spatiotemporal variation of phosphorus and the effect of local currents on its distribution in Petacalco Bay, Guerrero, Mexico
Authors: De-la-Lanza-Espino G , Penié-Rodríguez I , Hernández Pulido S
Published: August 2017

The contribution of continental water to the coastal zone has a significant impact on ecosystems worldwide. Continental waters provide nutrients in different concentrations and their distribution is conditioned by local marine circulation dynamics and seasonality of river inputs. The Balsas River, one of the most important in Mexico, discharges its water into Petacalco Bay, with a considerable nutrient content. This work studied the spatiotemporal variability of the orthophosphate and total phosphorus contents and their relation with salinity, turbidity and coastal circulation. Maximum orthophosphate concentrations in the bay were 19.56 ∞M in April/May, 10.50 ∞M in February and 9.31 ∞M in August. The high total phosphorus contents were 40.98 ∞M in April/May and 20.54 ∞M in August, indicating an eutrophied coastal environment, result of the wastewaters discharged by the industries established along the river's estuary and dispersed throughout the bay by the local currents. An accumulation of water originating from the Balsas River was recorded in the central-eastern portion of the bay. There were small cyclonic and anticyclonic superficial gyres off the Petacalco Estuary during most of the months studied (February, June, August, October and December) that had the same direction at 10 m depth or were inverted in April and December, with a displacement toward the E–NE, allowing us to verify the diffusion of the phosphorus.
O PAPEL DO LICENCIAMENTO AMBIENTAL NA MINIMIZAÇÃO DO CONSUMO DE ENERGIA NA INDÚSTRIA DE ABATE DE ANIMAIS
Authors: Souza Anderson Carneiro de , Orrico Silvio Roberto Magalhães , Agra Filho Severino Soares
Published: August 2017

O Brasil é um dos maiores produtores e exportadores de carne no mundo, com destaque para as indústrias de carne bovina e de frango. Tal atividade, como outras, ocasiona impactos ambientais que devem ser mitigados, sendo passível de licenciamento ambiental. Portanto, o objetivo desta pesquisa é avaliar o consumo de energia para o abate de animais, de acordo com dados do licenciamento ambiental do estado da Bahia e relacioná-los com os valores de “benchmarking” ou os resultados mais favoráveis praticados por esse setor. Foram utilizados dados secundários de consumo de energia de 25 empreendimentos licenciados pelo INEMA, no período de 2006 a 2012, contidos em documentos do processo de Licenciamento Ambiental, fornecidos pelas empresas para obtenção da licença ambiental. Os resultados de consumo de energia observados estão bastante aquém dos valores de referência praticados em outros países. Portanto, pode-se inferir que a análise do consumo não é considerada no mérito da apreciação do licenciamento ambiental, que se restringe apenas às medidas de controle e desconsidera a relevância preventiva de se buscar a ecoeficiência energética.
AVALIAÇÃO DO DESEMPENHO DE UMA ESTAÇÃO DE TRATAMENTO DE ÁGUA EM RELAÇÃO À TURBIDEZ, COR E PH DA ÁGUA
Authors: Cunha Almeida Marília , Macêdo Silva Maiara , De Paula Marcelo
Published: August 2017

O trabalho buscou estudar o desempenho do tratamento da água de uma estação de tratamento de água (ETA), por meio da análise de seus procedimentos operacionais e da qualidade da água. Foram realizadas análises estatísticas dos dados de turbidez, cor e pH. O tratamento é feito em ciclo completo e a água provém de um rio. Em relação às características climáticas, a região apresenta período seco e chuvoso. Quando se compara os dois períodos, observa-se uma diferença significativa nas características da água bruta, o que acarreta consequências ao tratamento, alterando a utilização ou não de coagulantes químicos e a frequência na lavagem dos filtros. Portanto, foi observado que as precipitações ocorridas trouxeram consequências diretas à qualidade da água bruta e indiretas ao tratamento, o que mostrou serem necessárias adequações na ETA, para melhorar a qualidade da água tratada e o desempenho do processo.
Three‐dimensional lithospheric S wave velocity model of the NE Tibetan Plateau and western North China Craton
Authors: Wang Xingchen , Li Yonghua , Ding Zhifeng , Zhu Lupei , Wang Chunyong , Bao Xuewei , Wu Yan
Published: August 2017

We present a new 3‐D lithospheric Vs model for the NE Tibetan Plateau (NETP) and the western North China Craton (NCC). First, high‐frequency receiver functions (RFs) were inverted using the neighborhood algorithm to estimate the sedimentary structure beneath each station. Then a 3D Vs model with unprecedented resolution was constructed by jointly inverting RFs and Rayleigh wave dispersions. A low‐velocity sedimentary layer with thicknesses varying from 2 to 10 km is present in the Yinchuan‐Hetao graben, Ordos block, and western Alxa block. Velocities from the middle‐lower crust to the uppermost mantle are generally high in the Ordos block and low in the Alxa block, indicating that the Alxa block is not part of the NCC. The thickened crust in southwestern Ordos block and western Alxa block suggests that they have been modified. Two crustal low‐velocity zones (LVZs) were detected beneath the Kunlun Fault (KF) zone and western Qilian Terrane (QLT). The origin of the LVZ beneath the KF zone may be the combined effect of shear heating, localized asthenosphere upwelling, and crustal radioactivity. The LVZ in the western QLT, representing an early stage of the LVZ that has developed in the KF zone, acts as a decollement to decouple the deformation between the upper and lower crust and plays a key role in seismogenesis. We propose that the crustal deformation beneath the NETP is accommodated by a combination of shear motion, thickening of the upper‐middle crust, and removal of lower crust.
Influence of pyroxene and spinel on the kinetics of peridotite serpentinization
Authors: Huang Ruifang , Song Maoshuang , Ding Xing , Zhu Sanyuan , Zhan Wenhuan , Sun Weidong
Published: August 2017

Hydrothermal experiments were performed at 311°C and 3.0 kbar on natural olivine and peridotite to investigate the kinetics of serpentinization. The results show that the rates of reaction strongly depend on grain sizes of solid reactants, with smaller grain sizes resulting in faster kinetics. After 27 days of reaction, the reaction extent was 99% for peridotite with grain sizes of <30 μm, and the reaction extent was 28% for grain sizes of 100–177 μm. Compared to peridotite, olivine is serpentinized at much slower rates, e.g., 5.3% of reaction extent was achieved for olivine with grain sizes of 100–177 μm after 27 days, approximately five times lower than that reached during peridotite serpentinization. Such contrasting results are due to the presence of pyroxene and spinel, an interpretation which is supported by a marked increase in reaction extents for experiments with the addition of pyroxene and spinel. The reaction extent achieved in experiments with 3 wt % spinel greatly increased to 98% after 27 days, much higher than that achieved during olivine serpentinization. These results appear to be related to pyroxene and spinel releasing Al and Cr during serpentinization. As indicated by compositions of serpentine, orthopyroxene lost ~60% of Al at a reaction extent of 59%. Influence of Al and Cr is suggested by a dramatic increase in reaction extents with the addition of Al2O3 and Cr2O3 powders. Olivine in natural geological settings is commonly associated with pyroxene and spinel; consequently, serpentinization kinetics may be much faster than previously thought.
Seismic velocity changes concentrated at the shallow structure as inferred from correlation analyses of ambient noise during volcano deformation at Izu‐Oshima, Japan
Authors: Takano Tomoya , Nishimura Takeshi , Nakahara Hisashi
Published: August 2017

We investigate the stress sensitivity of velocity changes at Izu‐Oshima in Japan using seismic interferometry method. We calculate cross correlation functions (CCFs) of ambient noises recorded by four seismic stations on the active volcano from 1 January 2012 to 31 December 2015 at 0.5–1 Hz, 1–2 Hz, and 2–4 Hz. Applying moving time windows to calculate cross spectrum between daily CCFs and reference CCF, which is the average for the all observation period, we compute daily velocity changes. The obtained velocity changes vary from −1% to 3% with a dominant period of about 1 year. We calculate areal strains by using Global Navigation Satellite Systems data at the volcano. It is evident that the velocity changes are well correlated with the areal strain changes whose linear trend is removed. The stress sensitivity of velocity changes, which are obtained from the observed velocity changes and areal strains, is lower at 0.5–1 Hz than that at higher frequencies: (7.1 ± 1.3) × 10−8 Pa−1 at 0.5–1 Hz, (1.4 ± 0.1) × 10−7 Pa−1 at 1–2 Hz, and (1.3 ± 0.1) × 10−7 Pa−1 at 2–4 Hz. Modeling the velocity changes of Rayleigh wave propagating in layered structures, we find that the observed velocity changes are concentrated in the upper 1 km of the structure. Since similar frequency dependency is recognized among the stress sensitivity of velocity changes reported in previous studies, we conclude that the velocity changes are localized in the shallow depth because of the increase of confining pressure.
Nonlinear softening of unconsolidated granular earth materials
Authors: Lieou Charles K. C. , Daub Eric G. , Guyer Robert A. , Johnson Paul A.
Published: August 2017

Unconsolidated granular earth materials exhibit softening behavior due to external perturbations such as seismic waves, namely, the wave speed and elastic modulus decrease upon increasing the strain amplitude above dynamics strains of about 10−6 under near‐surface conditions. In this letter, we describe a theoretical model for such behavior. The model is based on the idea that shear transformation zones—clusters of grains that are loose and susceptible to contact changes, particle displacement, and rearrangement—are responsible for plastic deformation and softening of the material. We apply the theory to experiments on simulated fault gouge composed of glass beads and demonstrate that the theory predicts nonlinear resonance shifts, reduction of the P wave modulus, and attenuation, in agreement with experiments. The theory thus offers insights on the nature of nonlinear elastic properties of a granular medium and potentially into phenomena such as triggering on earthquake faults.
Uplift, rupture, and rollback of the Farallon slab reflected in volcanic perturbations along the Yellowstone adakite hot spot track
Authors: Camp Victor E. , Ross Martin E. , Duncan Robert A. , Kimbrough David L.
Published: August 2017

Field, geochemical, and geochronological data show that the southern segment of the ancestral Cascades arc advanced into the Oregon back‐arc region from 30 to 20 Ma. We attribute this event to thermal uplift of the Farallon slab by the Yellowstone mantle plume, with heat diffusion, decompression, and the release of volatiles promoting high‐K calc‐alkaline volcanism throughout the back‐arc region. The greatest degree of heating is expressed at the surface by a broad ENE‐trending zone of adakites and related rocks generated by melting of oceanic crust from the Farallon slab. A hiatus in eruptive activity began at ca. 22–20 Ma but ended abruptly at 16.7 Ma with renewed volcanism from slab rupture occurring in two separate regions. The eastern rupture resulted in the extrusion of Steens Basalt during the ascent and melting of a dry mantle (plume) source contaminated with depleted mantle. The contemporaneous western rupture resulted in renewed subduction, melting of a wet mantle source, and the rejuvenation of high‐K calc‐alkaline volcanism near the Nevada‐California border at 16.7 Ma. Here the initiation of slab rollback is evident in the westward migration of arc volcanism at 7.8 km/Ma. Today, the uplifted slab is largely missing beneath the Oregon back‐arc region, replaced instead by a seismic hole that is bound on the south by the adakite hot spot track. We attribute slab destruction to thermal uplift and mechanical dislocation that culminated in rapid tearing of the slab from 17–15 Ma and possible foundering and sinking of slab segments from 16 to 10 Ma.
Plant species, not climate, controls aboveground biomass O2:CO2 exchange ratios in deciduous and coniferous ecosystems
Authors: Gallagher Morgan E. , Liljestrand Frasier L. , Hockaday William C. , Masiello Caroline A.
Published: August 2017

The oxidative ratio (OR) is the O2:CO2 ratio associated with photosynthesis, respiration, and other ecosystem gas exchange processes and can be reported on the scale of an individual leaf, an ecosystem, up to the entire terrestrial biosphere. The OR of the terrestrial biosphere is used to partition anthropogenic CO2 between oceanic and terrestrial carbon sinks, and the ease of measurement of this property on smaller scales suggests its potential for other uses. However, controls on the natural variation of OR are not understood in either organic matter pools or fluxes, and this lack of basic information limits the use of the tracer. Here we assess the annual variability of the OR of photosynthesis over ~decade for two temperate forests, one coniferous and one deciduous, and show that the photosynthetic OR signature is strongly dominated by plant species. We determined the OR of this flux by measuring the OR of carbon pools that close on annual or shorter timescales (leaves and individual tree rings), via solid‐state 13C NMR spectroscopy and elemental analysis. Leaf litter OR is different between coniferous and deciduous forests, but tree bole OR is constant between species. There was no significant change in leaf litter OR with time, nor any correlations between leaf litter OR and temperature or precipitation. During this time growing season precipitation varied by 95% from the time period average, and growing season temperature by 22%, demonstrating that on the decadal scale photosynthetic OR is invariant over significant shifts in these climate parameters.
In situ 15N labeling experiment reveals different long‐term responses to ammonium and nitrate inputs in N‐saturated subtropical forest
Authors: Liu Wenjing , Yu Longfei , Zhang Ting , Kang Ronghua , Zhu Jing , Mulder Jan , Huang Yongmei , Duan Lei
Published: August 2017

Chronically elevated deposition of reactive nitrogen (N), as ammonium (NH4+) and nitrate (NO3−), in subtropical forests with monsoonal climate has caused widespread N leaching in southern China. So far, little is known about the effect of further increases in N input and changes in the relative proportion of NH4+ and NO3− on turnover rate and fate of atmogenic N. Here we report a 15N tracer experiment in Tieshanping (TSP) forest, SW China, conducted as part of a long‐term N fertilization experiment, using NH4NO3 and NaNO3, where effects of a doubling of monthly N inputs were compared. In June 2012, the regular N fertilizers were replaced by their 15N‐labeled forms, viz., 15NH4NO3 and Na15NO3, as a single‐dose addition. Mass balances of N for the initial 1.5 years following label addition showed that for both treatments, 70% to 80% of the annual N input was leached as NO3−, both at ambient and at double N input rates. This confirms the earlier reported extreme case of N saturation at TSP. The 15N, added as Na15NO3, showed recoveries of about 74% in soil leachates, indicating that NO3− input at TSP is subject to a rapid and nearly quantitative loss through direct leaching as a mobile anion. By contrast, recoveries of 15N in soil leachates of only 33% were found if added as 15NH4NO3. Much of the 15N was immobilized in the soil and to a lesser extent in the vegetation. Thus, immobilization of fresh N input is significantly greater if added as NH4+, than as NO3−.
Climate change imposes phenological trade‐offs on forest net primary productivity
Authors: Duveneck Matthew J. , Thompson Jonathan R.
Published: August 2017

Climate warming is expected to lengthen growing seasons of temperate forest ecosystems and increase gross primary productivity. Simultaneously, warming is expected to increase summer ecosystem respiration, which could offset gains accrued from longer growing seasons. These responses have been observed during anomalously warm years, but the role of future climate change on phenological trade‐offs and how they affect net primary productivity (NPP) at regional scales in temperate forests remain unexplored. We simulated scenarios of climate change on monthly forest NPP throughout 18 million hectares of temperate forests in New England, USA, through year 2100. Using an ecophysiological model coupled to a forest landscape model, we simulated scenarios of climate change on monthly NPP. A high emission scenario (RCP 8.5), resulted in longer growing seasons that offset midsummer ecosystem respiration costs and produced greater annual NPP throughout the study landscape compared to simulations using the current climate. In spring and autumn months, temperature was positively associated with greater NPP; in summer months, the relationship was negative. Spatially, the greatest increase in NPP occurred in the warmer southern region under a warm climate scenario with increased precipitation. Under a warm scenario with drier conditions, the greatest increase in NPP occurred in the cooler northern region. Phenological trade‐offs will affect NPP of future forests and their potential to serve as a negative feedback to climate change. Barring other limitations, longer growing seasons will offset greater respiratory demands and contribute to increases in NPP throughout the temperate forests of New England in the future.
Photon Management through Virus‐Programmed Supramolecular Arrays
Authors: Veliz Frank A. , Ma Yingfang , Molugu Sudheer K. , Tiu Brylee David B. , Stewart Phoebe L. , French Roger H. , Steinmetz Nicole F.
Published: August 2017

Photon extraction and capture efficiency is a complex function of the material's composition, its molecular structure at the nanoscale, and the overall organization spanning multiple length scales. The architecture of the material defines the performance; nanostructured features within the materials enhance the energy efficiency. Photon capturing materials are largely produced through lithographic, top‐down, manufacturing schemes; however, there are limits to the smallest dimension achievable using this technology. To overcome these technological barriers, a bottom‐up nanomanufacturing is pursued. Inspired by the self‐programmed assembly of virus arrays in host cells resulting in iridescence of infected organisms, virus‐programmed, nanostructured arrays are studied to pave the way for new design principles in photon management and biology‐inspired materials science. Using the nanoparticles formed by plant viruses in combination with charged polymers (dendrimers), a bottom‐up approach is illustrated to prepare a family of broadband, low‐angular dependent antireflection mesoscale layered materials for potential application as photon management coatings. Measurement and theory demonstrate antireflectance and phototrapping properties of the virus‐programmed assembly. This opens up new bioengineering principles for the nanomanufacture of coatings and films for use in LED lighting and photovoltaics.
Cluster Recognition by Delaunay Triangulation of Synaptic Proteins in 3D
Authors: Boening Daniel , Gauthier‐Kemper Anne , Gmeiner Benjamin , Klingauf Jürgen
Published: August 2017

The advent of super‐resolution microscopy opens up the opportunity to study biological structures in unprecedented detail. However, revealing quantitative information about the spatial organization of a set of labeled proteins requires sophisticated analysis. This study introduces a novel robust cluster recognition algorithm based on Delaunay triangulation (CRADT), which can handle complex datasets generated by 3D super‐resolution microscopy. This algorithm allows determining volume and shape of protein clusters in 3D. The study demonstrates its performance by applying this algorithm on dual‐color 3D super‐resolved measurements of mouse hippocampal synapses, stained against the presynaptic active zone marker protein Bassoon and the opposing postsynaptic density protein Homer as well as the exo‐ and endocytosis machinery proteins Synaptobrevin and Clathrin.
A Novel Solution‐Processable n‐Dopant Based on 1,4‐Dihydropyridine Motif for High Electrical Conductivity of Organic Semiconductors
Authors: Shi Ke , Lu Zuo‐Yu , Yu Zi‐Di , Liu Han‐Yu , Zou Ye , Yang Chi‐Yuan , Dai Ya‐Zhong , Lu Yang , Wang Jie‐Yu , Pei Jian
Published: August 2017

p‐ or n‐Dopants have played significant roles in the improvement of organic electronic devices through the controllable doping of organic semiconductors. However, there has been little study of air‐stable n‐dopants under ambient conditions with strong doping capability due to the low electron affinities of organic semiconductors. Herein, a 1,4‐dihydropyridine‐based derivative is designed and facilely synthesized as an efficient n‐dopant. The doping process is systematically investigated by UV–vis–NIR spectroscopy in solution and ultraviolet photoelectron spectroscopy in the solid state. Excellent conductivities are obtained for a variety of doped n‐type semiconductors via a simple solution process without further treatment, suggesting a broad class of 1,4‐dihydropyridine derivatives could be used as n‐dopants in future organic electronic devices.
Enzymatic C−H Oxidation–Amidation Cascade in the Production of Natural and Unnatural Thiotetronate Antibiotics with Potentiated Bioactivity
Authors: Li Jie , Tang Xiaoyu , Awakawa Takayoshi , Moore Bradley S.
Published: August 2017

The selective activation of unreactive hydrocarbons by biosynthetic enzymes has inspired new synthetic methods in C−H bond activation. Herein, we report the unprecedented two‐step biosynthetic conversion of thiotetromycin to thiotetroamide C involving the tandem oxidation and amidation of an unreactive ethyl group. We detail the genetic and biochemical basis for the terminal amidation in thiotetroamide C biosynthesis, which involves a uniquely adapted cytochrome P450–amidotransferase enzyme pair and highlights the first oxidation–amidation enzymatic cascade reaction leading to the selective formation of a primary amide group from a chemically inert alkyl group. Motivated by the ten‐fold increase in antibiotic potency of thiotetroamide C ascribed to the acetamide group and the unusual enzymology involved, we enzymatically interrogated diverse thiolactomycin analogues and prepared an unnatural thiotetroamide C analogue with potentiated bioactivity compared to the parent molecule.
The Hydrophobic Gap at High Hydrostatic Pressures
Authors: Wirkert Florian J. , Hölzl Christoph , Paulus Michael , Salmen Paul , Tolan Metin , Horinek Dominik , Nase Julia
Published: August 2017

We have gained new insight into the so‐called hydrophobic gap, a molecularly thin region of decreased electron density at the interface between water and a solid hydrophobic surface, by X‐ray reflectivity experiments and molecular dynamics simulations at different hydrostatic pressures. Pressure variations show that the hydrophobic gap persists up to a pressure of 5 kbar. The electron depletion in the interfacial region strongly decreases with an increase in pressure, indicating that the interfacial region is compressed more strongly than bulk water. The decrease is most significant up to 2 kbar; beyond that, the pressure response of the depletion is less pronounced.
Molecular Dynamics of Hexamethylbenzene at Low Temperatures: Evidence of Unconventional Magnetism Based on Rotational Motion of Protons
Authors: Yen Fei , Zhao Zhenzheng , Hu Sixia , Chen Lang
Published: August 2017

The types of magnetism known to date are all mainly based on contributions from electron motion. We show how rotational motion of protons (H+) within the methyl groups in hexamethylbenzene (C6(CH3)6) also contribute significantly to the magnetic susceptibility. Starting from below 118 K, as the rotational motion of the methyl groups set in, an associated magnetic moment positive in nature due to charge of the protons renders the susceptibility to become anomalously dependent on temperature. Starting from 20 K, the susceptibility diverges with decreasing temperature indicative of spin–spin interactions between methyl groups aligned in a previously unclassified type of anti‐ferromagnetic configuration. Complementary dielectric constant measurements also show the existence of magneto‐dielectric coupling. Our findings allow for the study of strongly correlated systems that are based on a species that possesses much slower dynamics.
In Situ Investigation of Methane Dry Reforming on Metal/Ceria(111) Surfaces: Metal–Support Interactions and C−H Bond Activation at Low Temperature
Authors: Liu Zongyuan , Lustemberg Pablo , Gutiérrez Ramón A. , Carey John J. , Palomino Robert M. , Vorokhta Mykhailo , Grinter David C. , Ramírez Pedro J. , Matolín Vladimír , Nolan Michael , Ganduglia‐Pirovano M. Verónica , Senanayake Sanjaya D. , Rodriguez José A.
Published: August 2017

Studies with a series of metal/ceria(111) (metal=Co, Ni, Cu; ceria=CeO2) surfaces indicate that metal–oxide interactions can play a very important role for the activation of methane and its reforming with CO2 at relatively low temperatures (600–700 K). Among the systems examined, Co/CeO2(111) exhibits the best performance and Cu/CeO2(111) has negligible activity. Experiments using ambient pressure X‐ray photoelectron spectroscopy indicate that methane dissociates on Co/CeO2(111) at temperatures as low as 300 K—generating CHx and COx species on the catalyst surface. The results of density functional calculations show a reduction in the methane activation barrier from 1.07 eV on Co(0001) to 0.87 eV on Co2+/CeO2(111), and to only 0.05 eV on Co0/CeO2−x(111). At 700 K, under methane dry reforming conditions, CO2 dissociates on the oxide surface and a catalytic cycle is established without coke deposition. A significant part of the CHx formed on the Co0/CeO2−x(111) catalyst recombines to yield ethane or ethylene.
Performance equivalency between computer‐based and traditional pen‐and‐paper assessment: A case study in clinical anatomy
Authors: Guimarães Bruno , Ribeiro José , Cruz Bernardo , Ferreira André , Alves Hélio , Cruz‐Correia Ricardo , Madeira Maria Dulce , Ferreira Maria Amélia
Published: August 2017

The time, material, and staff‐consuming nature of anatomy's traditional pen‐and‐paper assessment system, the increase in the number of students enrolling in medical schools and the ever‐escalating workload of academic staff have made the use of computer‐based assessment (CBA) an attractive proposition. To understand the impact of such shift in the assessment method, an experimental study evaluating its effect on students’ performance was designed. Additionally, students’ opinions toward CBA were gathered. Second‐year medical students attending a Clinical Anatomy course were randomized by clusters in two groups. The pen‐and‐paper group attended two sessions, each consisting of a traditional sectional anatomy steeplechase followed by a theoretical examination, while the computer group was involved in two similar sessions conducted in a computerized environment. At the end of each of the computer sessions, students in this group filled an anonymous questionnaire. In the first session, pen‐and‐paper group students scored significantly better than computer‐group students in both the steeplechase (mean ± standard deviation: 66.00 ± 14.15% vs. 43.50 ± 19.10%; P < 0.001) and the theoretical examination (52.50 ± 12.70% vs. 39.00 ± 21.10%; P < 0.001). In the second session, no statistically significant differences were found for both the steeplechase (59.50 ± 17.30% vs. 54.50 ± 17.00%; P = 0.085) and the theoretical examination (57.50 ± 13.70% vs. 54.00 ± 14.30%; P = 0.161). Besides, an intersession improvement in students’ perceptions toward CBA was registered. These results suggest that, after a familiarization period, CBA might be a performance equivalent and student accepted alternative to clinical anatomy pen‐and‐paper theoretical and practical examinations. Anat Sci Educ 11: 124–136. © 2017 American Association of Anatomists.
Improved medical student perception of ultrasound using a paired anatomy teaching assistant and clinician teaching model
Authors: Smith Jacob P. , Kendall John L. , Royer Danielle F.
Published: August 2017

This study describes a new teaching model for ultrasound (US) training, and evaluates its effect on medical student attitudes toward US. First year medical students participated in hands‐on US during human gross anatomy (2014 N = 183; 2015 N = 182). The sessions were facilitated by clinicians alone in 2014, and by anatomy teaching assistant (TA)‐clinician pairs in 2015. Both cohorts completed course evaluations which included five US‐related items on a four‐point scale; cohort responses were compared using Mann‐Whitney U tests with significance threshold set at 0.05. The 2015 survey also evaluated the TAs (three items, five‐point scale). With the adoption of the TA‐clinician teaching model, student ratings increased significantly for four out of five US‐items: “US advanced my ability to learn anatomy” increased from 2.91 ± 0.77 to 3.35 ± 0.68 (P < 0.0001), “Incorporating US increased my interest in anatomy” from 3.05 ± 0.84 to 3.50 ± 0.71 (P < 0.0001), “US is relevant to my current educational needs” from 3.36 ± 0.63 to 3.54 ± 0.53 (P = 0.015), and “US training should start in Phase I” from 3.36 ± 0.71 to 3.56 ± 0.59 (P = 0.010). Moreover, more than 84% of students reported that TAs enhanced their understanding of anatomy (mean 4.18 ± 0.86), were a valuable part of US training (mean 4.23 ± 0.89), and deemed the TAs proficient in US (mean 4.24 ± 0.86). By using an anatomy TA‐clinician teaching team, this study demonstrated significant improvements in student perceptions of the impact of US on anatomy education and the relevancy of US training to the early stages of medical education. Anat Sci Educ 11: 175–184. © 2017 American Association of Anatomists.
Metallofullerenol Inhibits Cellular Iron Uptake by Inducing Transferrin Tetramerization
Authors: Li Jinxia , Xing Xueqing , Sun Baoyun , Zhao Yuliang , Wu Zhonghua
Published: August 2017

Herein, A549 tumor cell proliferation was confirmed to be positively dependent on the concentration of Fe3+ or transferrin (Tf). Gd@C82(OH)22 or C60(OH)22 effectively inhibited the iron uptake and the subsequent proliferation of A549 cells. The conformational changes of Tf mixed with FeCl3, GdCl3, C60(OH)22 or Gd@C82(OH)22 were obtained by SAXS. The results demonstrate that Tf homodimers can be decomposed into monomers in the presence of FeCl3, GdCl3 or C60(OH)22, but associated into tetramers in the presence of Gd@C82(OH)22. The larger change of SAXS shapes between Tf+C60(OH)22 and Tf+FeCl3 implies that C60(OH)22 is bound to Tf, blocking the iron‐binding site. The larger deviation of the SAXS shape from a possible crystal structure of Tf tetramer implies that Gd@C82(OH)22 is bound to the Tf tetramer, thus disturbing iron transport. This study well explains the inhibition mechanism of Gd@C82(OH)22 and C60(OH)22 on the iron uptake and the proliferation of A549 tumor cells and highlights the specific interactions of a nanomedicine with the target biomolecules in cancer therapy.
Boundary Stabilization of a Cosserat Elastic Body
Authors: Najafi Ali , Alasty Aria , Vatankhah Ramin , Eghtesad Mohammad , Daneshmand Farhang
Published: August 2017

Boundary stabilization of vibrating three‐dimensional Cosserat elastic solids are studied using mathematical tools, such as operator theory and semigroup techniques. The advantages of the boundary control laws for both boundary stabilization problems are investigated. The boundary stabilization problems are studied using a Lyapunov stability method and LaSalle's invariant set theorem. Numerical simulations are provided to illustrate the effectiveness and performance of the designed control scheme.