bluuebunny/crossref_metadata_2025 huggingface dataset:
Sources and composition of PM2.5 in the Colorado Front Range during the DISCOVER‐AQ study
Authors: Valerino M. J. , Johnson J. J. , Izumi J. , Orozco D. , Hoff R. M. , Delgado R. , Hennigan C. J.
Published: December 2016

Measurements of particulate matter (PM2.5) chemical composition were carried out in Golden, CO, during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER‐AQ) field study. Chemical composition was dominated by organic compounds, which comprised an average of 75% of the PM2.5 mass throughout the study. Most of the organic matter was secondary (i.e., secondary organic aerosol) and appears to derive predominantly from regional sources, rather than the Denver metropolitan area. The concentration and composition of PM2.5 in Golden were strongly influenced by highly regular wind patterns and the site's close proximity to the mountains (~5 km). This second factor may be the cause of distinct differences between observations in Golden and those in downtown Denver, despite a distance between the sites of only ~15 km. Concentrations of aerosol nitrate, ammonium, and elemental carbon increased significantly during the daytime when the winds were from the northeast, indicating a strong local source for these compounds. Local sources of dust appeared to minimally impact the Golden site, although this was not likely representative of other conditions in the Colorado Front Range. Conversely, dust that had undergone long‐range transport from the southwestern U.S. likely impacted the entire Colorado Front Range, including Golden. During this event, water‐soluble Ca2+ concentrations exceeded 1 µg m−3, and the PM2.5/PM10 ratio reached its lowest level throughout the study. The long‐range transport of wildfire emissions also impacted the Colorado Front Range for 1–2 days during DISCOVER‐AQ. The smoke event was characterized by high concentrations of organics and water‐soluble K+. The results show a complex array of sources, and atmospheric processes influence summertime PM in the Colorado Front Range.
Mineral dust over west and central Sahel: Seasonal patterns of dry and wet deposition fluxes from a pluriannual sampling (2006–2012)
Authors: Marticorena B. , Chatenet B. , Rajot J. L. , Bergametti G. , Deroubaix A. , Vincent J. , Kouoi A. , Schmechtig C. , Coulibaly M. , Diallo A. , Koné I. , Maman A. , NDiaye T. , Zakou A.
Published: December 2016

Total and wet mineral dust deposition has been monitored since 2006 at three Sahelian stations in Senegal, Mali, and Niger, respectively at the weekly and the event time scale. Average annual deposited mass fluxes range from 75 to 183 g m−2 yr−1, from west to east. Deposition fluxes exhibit a clear seasonal cycle in Mali and Niger. High wet deposition fluxes result from an optimum phasing between dust concentration and precipitation: the maximum occurring at the beginning of the wet season, after the maximum of dust concentration and before the precipitation maximum. The contribution of wet to total deposition varies from 67% in Mali to 8% in Senegal. It is the main factor of variability of the deposition fluxes from year to year and at the seasonal scale in Niger and Mali. Wet deposition fluxes in Mali and Niger are mainly due to the wash out of dust emitted by convective systems. In Senegal, the deposition fluxes are lower and dominated by dry deposition (92% of the annual deposition flux). This is due to the low occurrence of convective systems producing local dust emissions and intense wet deposition. The dry deposition fluxes are primarily driven by the variability of the dust concentration. The dry deposition velocities derived from our measurements are consistent with those estimated by theoretical models. Scavenging ratios computed from the measured wet deposition fluxes, dust concentrations, and precipitation are anticorrelated with precipitation amounts. This suggests that most of the atmospheric dust is scavenged at the very beginning of the precipitation events.
A revised budget for Cenozoic sedimentary carbon subduction
Authors: Clift Peter D.
Published: December 2016

Carbon plays a pivotal role in governing the climate and biosphere of Earth, yet quantification of carbon's long‐term cycling from the mantle to the surface remains contentious. Sedimentary carbon represents a significant part of the budget and can be recycled to the mantle if underthrust in subduction zones. I estimate that ~60 megaton per year (Mt/yr) is presently being subducted below the outer fore arc, 80% in the form of carbonate carbon, significantly more than previously estimated. Sedimentary carbon represents around two thirds of the total carbon input at the trenches. An additional 7 Mt/yr is averaged over the Cenozoic as a result of passive margin subduction during continental collision (~83% CaCO3). This revision brings the input and output budgets within the range of uncertainty. Degassing from arc volcanoes and fore arcs totals ~55 Mt/yr. When carbon in hydrothermal veins in the altered oceanic crust and serpentinized upper mantle is accounted for, a net flux to the mantle appears likely. The efficiency of carbon subduction is largely controlled by the carbonate contents of the sediment column and is partly linked to the latitude of the trench. Accretionary margins are the biggest suppliers of carbon to the mantle wedge, especially Java, Sumatra, Andaman‐Burma, and Makran, reflecting the inefficiency of offscraping, the thickness of the subducting sediment, and the trench length. The western Pacific trenches are negligible sinks of sedimentary carbon. Increases in deep‐sea carbonate in the Oligocene and middle Mesozoic had a large impact on the subduction budget, increasing it greatly compared to earlier times.
A long‐term perspective of the hydroclimatological impacts of atmospheric rivers over the central United States
Authors: Nayak Munir Ahmad , Villarini Gabriele
Published: December 2016

The focus of this study is on the climatology of atmospheric rivers (ARs) over the central United States using six atmospheric reanalysis products. This climatology is used to understand the long‐term impacts of ARs on annual precipitation, precipitation extremes, and flooding over the central United States. The relationship between the frequency of ARs and three prominent large‐scale atmospheric modes [Pacific‐North American (PNA) teleconnection, Artic Oscillation (AO), and North Atlantic Oscillation (NAO)] is investigated, and the results are used to statistically model the frequency of ARs at the seasonal scale. AR characteristics (e.g., frequency, duration) are generally robust across the different reanalysis products. ARs exhibit a marked seasonality, with the largest activity in winter (more than 10 ARs per season on average), and the lowest in summer (less than two ARs per season on average). Overall, the duration of most ARs is less than 3 days, but exceptionally persistent ARs (more than 6 days) are also observed. The year‐to‐year variations in the total annual precipitation over the central United States are largely explained by the variations in AR‐related precipitation. Moreover, 40% of the top 1% daily precipitation extremes are associated with ARs, and more than 70% of the annual instantaneous peak discharges and peaks‐overthreshold floods are associated with these storms, in particular during winter and spring. The seasonal frequency of ARs can be described in terms of large‐scale atmospheric modes, with PNA playing a major role in particular in winter and spring.
Improving physically based snow simulations by assimilating snow depths using the particle filter
Authors: Magnusson Jan , Winstral Adam , Stordal Andreas S. , Essery Richard , Jonas Tobias
Published: December 2016

Data assimilation can help to ensure that model results remain close to observations despite potential errors in the model, parameters, and inputs. In this study, we test whether assimilation of snow depth observations using the particle filter, a generic data assimilation method, improves the results of a multilayer energy‐balance snow model, and compare the results against a direct insertion method. At the field site Col de Porte in France, the particle filter reduces errors in SWE, snowpack runoff, and soil temperature when forcing the model with coarse resolution reanalysis data, which is a typical input scenario for operational simulations. For those variables, the model performance after assimilation of snow depths is similar to model performance when forcing with high‐quality, locally observed input data. Using the particle filter, we could also estimate a snowfall correction factor accurately at Col de Porte. The assimilation of snow depths also improves forecasts with lead‐times of, at least, 7 days. At further 40 sites in Switzerland, the assimilation of snow depths in a model forced with numerical weather prediction data reduces the root‐mean‐squared‐error for SWE by 64% compared to the model without assimilation. The direct insertion method shows similar performance as the particle filter, but is likely to produce inconsistencies between modeled variables. The particle filter, on the other hand, avoids such limitations without loss of performance. The methods proposed in this study efficiently reduces errors in snow simulations, seems applicable for different climatic and geographic regions, and are easy to deploy.
Impact of social preparedness on flood early warning systems
Authors: Girons Lopez M. , Di Baldassarre G. , Seibert J.
Published: December 2016

Flood early warning systems play a major role in the disaster risk reduction paradigm as cost‐effective methods to mitigate flood disaster damage. The connections and feedbacks between the hydrological and social spheres of early warning systems are increasingly being considered as key aspects for successful flood mitigation. The behavior of the public and first responders during flood situations, determined by their preparedness, is heavily influenced by many behavioral traits such as perceived benefits, risk awareness, or even denial. In this study, we use the recency of flood experiences as a proxy for social preparedness to assess its impact on the efficiency of flood early warning systems through a simple stylized model and implemented this model using a simple mathematical description. The main findings, which are based on synthetic data, point to the importance of social preparedness for flood loss mitigation, especially in circumstances where the technical forecasting and warning capabilities are limited. Furthermore, we found that efforts to promote and preserve social preparedness may help to reduce disaster‐induced losses by almost one half. The findings provide important insights into the role of social preparedness that may help guide decision‐making in the field of flood early warning systems.
Tidal controls on riverbed denitrification along a tidal freshwater zone
Authors: Knights Deon , Sawyer Audrey H. , Barnes Rebecca T. , Musial Cole T. , Bray Samuel
Published: December 2016

In coastal rivers, tidal pumping enhances the exchange of oxygen‐rich river water across the sediment‐water interface, controlling nitrogen cycling in riverbed sediment. We developed a one‐dimensional, fluid flow and solute transport model that quantifies the influence of tidal pumping on nitrate removal and applied it to the tidal freshwater zone (TFZ) of White Clay Creek (Delaware, USA). In field observations and models, both oxygenated river water and anoxic groundwater deliver nitrate to carbon‐rich riverbed sediment. A zone of nitrate removal forms beneath the aerobic interval, which expands and contracts over daily timescales due to tidal pumping. At high tide when oxygen‐rich river water infiltrates into the bed, denitrification rates decrease by 25% relative to low tide. In the absence of tidal pumping, our model predicts that the aerobic zone would be thinner, and denitrification rates would increase by 10%. As tidal amplitude increases toward the coast, nitrate removal rates should decrease due to enhanced oxygen exchange across the sediment‐water interface, based on sensitivity analysis. Denitrification hot spots in TFZs are more likely to occur in less permeable sediment under lower tidal ranges and higher rates of ambient groundwater discharge. Our models suggest that tidal pumping is not efficient at removing surface water nitrate but can remove up to 81% of nitrate from discharging groundwater in the TFZ of White Clay Creek. Given the high population densities of coastal watersheds, the reactive riverbeds of TFZs play a critical role in mitigating new nitrogen loads to coasts.
Experiment on temporal variation of bed load transport in response to changes in sediment supply in streams
Authors: Elgueta‐Astaburuaga Maria A. , Hassan Marwan A.
Published: December 2016

A flume experiment was conducted to study channel adjustment to episodic sediment supply in mountain streams. The bulk sediment used for the bed and feed included grain sizes 0.5–64 mm with geometric mean D
of 5.7 mm. Water discharge was held constant for 40 h, and 300 kg of sediment was supplied through a range of scenarios. Bed slope, sediment storage, sediment transport, and bed surface texture responded to sediment supply. During the first of seven runs, bed slope decreased from 0.022 m
m (flume slope) to 0.018 m
m due to sediment starvation. Bed slope increased beginning in the second run as the bed aggraded due to preferential storage of grains >8 mm. Transport rate and bed‐surface particle size were significantly affected by magnitude‐frequency of sediment feed. Under constant feed, transport rate increased gradually and D
ranged between 12 and 15 mm. Instead, sediment pulses caused a pronounced increase in sediment transport rate and surface fining, trends that were inverted as sediment evacuated. At the run scale, sediment transport and storage behaved as with constant feed if pulse relaxation time exceeded time between pulses. The increase in transport rate and surface fining were proportional to pulse size. After the 300 kg pulse, transport rate reached
and D
was <10 mm. After 75 kg pulses, transport rate reached
and D
was >12 mm. Textural differences on the initial bed surface influenced the patterns of sediment transport. Channel adjustment was controlled by magnitude‐frequency of sediment feed and not by total feed.
A narrative method for analyzing transitions in urban water management: The case of the Miami‐Dade Water and Sewer Department
Authors: Treuer Galen , Koebele Elizabeth , Deslatte Aaron , Ernst Kathleen , Garcia Margaret , Manago Kim
Published: December 2016

Although the water management sector is often characterized as resistant to risk and change, urban areas across the United States are increasingly interested in creating opportunities to transition toward more sustainable water management practices. These transitions are complex and difficult to predict – the product of water managers acting in response to numerous biophysical, regulatory, political, and financial factors within institutional constraints. Gaining a better understanding of how these transitions occur is crucial for continuing to improve water management. This paper presents a replicable methodology for analyzing how urban water utilities transition toward sustainability. The method combines standardized quantitative measures of variables that influence transitions with contextual qualitative information about a utility's unique decision making context to produce structured, data‐driven narratives. Data‐narratives document the broader context, the utility's pretransition history, key events during an accelerated period of change, and the consequences of transition. Eventually, these narratives should be compared across cases to develop empirically‐testable hypotheses about the drivers of and barriers to utility‐level urban water management transition. The methodology is illustrated through the case of the Miami‐Dade Water and Sewer Department (WASD) in Miami‐Dade County, Florida, and its transition toward more sustainable water management in the 2000s, during which per capita water use declined, conservation measures were enacted, water rates increased, and climate adaptive planning became the new norm.
Low‐Cycle Fatigue Properties and Life Prediction of the Steels with Trace Silicon
Authors: Zhang Meng Xiao , Pang Jian Chao , Zhu Li Bei , Zhang Zhen Jun , Nie Liang Liang , Mao Yun Xian , Chen Man , Zhang Zhe Feng
Published: December 2016

For the steels with trace silicon, the tensile properties, low‐cycle fatigue properties, fatigue fracture morphologies, dislocation evolutions, and life predictions of 550TG and SD320, are investigated. It is found that cyclic hardening appears in 550TG and opposite tendency in SD320, respectively; the dislocation density decreases after fatigue experiment for the two materials. The sub‐grain boundaries in 550TG and dynamic recovery in SD320 has been discussed. The dislocation planar and wavy slip in 550TG and only planar slip in SD320 can be found. For life prediction, Basquin & Manson‐Coffin and hysteretic energy relationships are more appropriate. This study will be useful for the improvement of fatigue property.
Flexible Triboelectric Nanogenerator Based on Carbon Nanotubes for Self‐Powered Weighing
Authors: Khan Saeed Ahmed , Zhang Hu Lin , Xie Yuhang , Gao Min , Shah Madad Ali , Qadir Abdul , Lin Yuan
Published: December 2016

Diverse approaches have been adopted on harvesting ambient energy as sustainable, maintenance free, and green power sources for driving some small electronics due to the increasingly serious energy crisis. By coupling triboelectric effect and electrostatic induction, triboelectric nanogenerators (TENGs) can harvest mechanical energy with simplicity, cost‐effectiveness, and robustness. A flexible TENG based on carbon nanotubes (CNTs) fabricated via chemical vapor deposition (CVD) method have been introduced. The fabricated TENG can deliver output voltage of 20 V with the output power of 10.3 μW at a load of 40 MΩ, which can directly drive several green LEDs. In addition, commercial capacitors can be charged by TENG for energy storage, which is then utilized to drive thermal sensor. Due to the subtle structure, the TENG is proved capable of self‐powered weighing.
High‐Performance UV–Vis–NIR Phototransistors Based on Single‐Crystalline Organic Semiconductor–Gold Hybrid Nanomaterials
Authors: Jung Ji Hyung , Yoon Min Ji , Lim Ju Won , Lee Yoon Ho , Lee Kang Eun , Kim Dong Ha , Oh Joon Hak
Published: December 2016

Hybrid materials in optoelectronic devices can generate new functionality or provide synergistic effects that enhance the properties of each component. Here, high‐performance phototransistors with broad spectral responsivity in UV–vis–near‐infrared (NIR) regions, using gold nanorods (Au NRs)‐decorated n‐type organic semiconductor and N,N′‐bis(2‐phenylethyl)‐perylene‐3,4:9,10‐tetracarboxylic diimide (BPE‐PTCDI) nanowires (NWs) are reported. By way of the synergistic effect of the excellent photo‐conducting characteristics of single‐crystalline BPE‐PTCDI NW and the light scattering and localized surface plasmon resonances (LSPR) of Au NRs, the hybrid system provides new photo‐detectivity in the NIR spectral region. In the UV–vis region, hybrid nanomaterial‐based phototransistors exhibit significantly enhanced photo‐responsive properties with a photo‐responsivity (R) of 7.70 × 105 A W−1 and external quantum efficiency (EQE) of 1.42 × 108% at the minimum light intensity of 2.5 µW cm−2, which are at least tenfold greater than those of pristine BPE‐PTCDI NW‐based ones and comparable to those of high‐performance inorganic material‐based devices. While a pristine BPE‐PTCDI NW‐based photodetector is insensitive to the NIR spectral region, the hybrid NW‐based phototransistor shows an R of 10.7 A W−1 and EQE of 1.35 × 103% under 980 nm wavelength‐NIR illumination. This work demonstrates a viable approach to high‐performance photo‐detecting systems with broad spectral responsivity.
Highly Efficient and Stable Perovskite Solar Cells Based on Monolithically Grained CH3NH3PbI3 Film
Authors: Fei Chengbin , Li Bo , Zhang Rong , Fu Haoyu , Tian Jianjun , Cao Guozhong
Published: December 2016

The synthesis and growth of perovskite films with controlled crystallinity and microstructure for highly efficient and stable solar cells is a critical issue. In this work, thiourea is introduced into the CH3NH3PbI3 precursor with two‐step sequential ethyl acetate (EA) interfacial processing. This is shown for the first time to grow compact microsized and monolithically grained perovskite films. X‐ray diffraction patterns and infrared spectroscopy are used to prove that thiourea significantly impacts the perovskite crystallinity and morphology by forming the intermediate phase MAI·PbI2·SC(NH2)2. Afterward, the residual thiourea which coursed charge recombination is completely extracted by the sequential EA processing. The product has improved light harvesting, suppressed defect state, and enhanced charge separation and transport. The sequentially EA processed perovskite solar cells offer an impressive 18.46% power conversion efficiency and excellent stability in ambient air. More importantly, the EA postprocessed perovskite solar cells also have excellent voltage response under ultraweak light (0.05% sun) with promising utility in photodetectors and photoelectric sensors.
Polydopamine‐Inspired, Dual Heteroatom‐Doped Carbon Nanotubes for Highly Efficient Overall Water Splitting
Authors: Qu Konggang , Zheng Yao , Jiao Yan , Zhang Xianxi , Dai Sheng , Qiao Shi‐Zhang
Published: December 2016

Overall water splitting involved hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are critical for renewable energy conversion and storage. Heteroatom‐doped carbon materials have been extensively employed as efficient electrocatalysts for independent HER or OER processes, while those as the bifunctional catalysts for simultaneously generating H2 and O2 by splitting water have been seldom reported. Inspired by the unparalleled virtues of polydopamine, the authors devise the facile synthesis of nitrogen and sulfur dual‐doped carbon nanotubes with in situ, homogenous and high concentration sulfur doping. The newly developed dual‐doped electrocatalysts display superb bifunctional catalytic activities for both HER and OER in alkaline solutions, outperforming all other reported carbon counterparts. Experimental characterizations confirm that the excellent performance is attributed to the multiple doping together with efficient mass and charge transfer, while theoretical computations reveal the promotion effect of secondary sulfur dopant to enhance the spin density of dual‐doped samples and consequently to form highly electroactive sites for both HER and OER.
Tuning Multimetallic Ordered Intermetallic Nanocrystals for Efficient Energy Electrocatalysis
Authors: Luo Mingchuan , Sun Yingjun , Wang Lei , Guo Shaojun
Published: December 2016

Ordered intermetallic alloys have attracted extensive attention as advanced electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs) reactions with much improved activity and stability. Here, latest progress in tuning intermetallic Pt‐ and Pd‐based nanocrystals with tunable morphology and structure for catalyzing both the cathodic reduction of oxygen and anodic oxidation of fuels (e.g., methanol, ethanol and formic acid) in PEMFCs is highlighted. Making/tuning interesting intermetallic PtM (M = Fe, Co, Pb, Cu, etc.)‐based nanocrystals for boosting oxygen reduction reaction with high activity and stability by using/controlling high‐temperature annealing treatment is discussed. In all the reported Pt‐based intermetallic nanocrystals, controlling the degree of ordering under the proper high temperature treatment is the key for achieving the optimized electrocatalysis. In order to search for cheaper catalysts, the progress on making Pd‐based intermetallic nanocrystals is also discussed. Furthermore, future research directions are proposed and discussed to further enhance the efficiency of such unique intermetallic multimetallic nanocatalysts. This report aims to demonstrate the potential of ordered intermetallic strategy for boosting electrocatalysis and stimulating more research efforts in this field.
Modeling layered crystal growth at increasing supersaturation by connecting growth regimes
Authors: Tilbury Carl J. , Doherty Michael F.
Published: December 2016

Mechanistic modeling facilitates rational crystallization engineering and design space screening. For an accurate model, the dominant growth mechanism operating on each face must be determined, which is highly dependent on supersaturation. Considering the case of centrosymmetric growth units, we developed and connected existing mechanistic expressions for spiral and two‐dimensional‐nucleation growth regimes, through application of stationary nucleation rate theory. Our approach enables calculation of crossover supersaturations and forms a framework to model the specific mechanism operating on each face under given crystallization conditions. Increasing supersaturation can change the crystal morphology; as face families switch growth mechanisms, they may grow out of the steady‐state shape, or influence its aspect ratio. Application of the model to naphthalene, biphenyl, pentaerythritol and β‐HMX shows the ability to capture experimentally observed examples of such supersaturation‐dependent crystal habits. This methodology broadens the applicability of mechanistic crystal growth modeling to include higher‐supersaturation industrial processes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1338–1352, 2017
Ionic liquids for absorption and separation of gases: An extensive database and a systematic screening method
Authors: Zhao Yongsheng , Gani Rafiqul , Afzal Raja Muhammad , Zhang Xiangping , Zhang Suojiang
Published: December 2016

Ionic liquids (ILs) have attracted considerable attention in both the academic and industrial communities for absorbing and separating gases. However, a data‐rich and well‐structured systematic database has not yet been established, and screening for highly efficient ILs meeting various requirements remains a challenging task. In this study, an extensive database of estimated Henry's law constants of twelve gases in more than ten thousand ILs at 313.15 K is established using the COSMO‐RS method. Based on the database, a new systematic and efficient screening method for IL selection for the absorption and separation of gases subject to important target properties is proposed. Application of the database and the screening method is highlighted through case studies involving two important gases separation problems (CO2 from CH4 and C2H2 from C2H4). The results demonstrate the effectiveness of using the screening method together with the database to explore and screen novel ILs meeting specific requirements for the absorption and separation of gases. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1353–1367, 2017
The analysis of solubility, absorption kinetics of CO2 absorption into aqueous 1‐diethylamino‐2‐propanol solution
Authors: Liu Helei , Xiao Min , Liang Zhiwu , Tontiwachwuthikul Paitoon
Published: December 2016

In this present work, the CO2 absorption performance of aqueous 1‐diethylamino‐2‐propanol (1DEA2P) solution was studied with respect to CO2 equilibrium solubility, absorption kinetics, and absorption heat. The equilibrium solubility of CO2 in 2M 1DEA2P solution was measured over the temperature range from 298 to 333 K and CO2 partial pressure range from 8 to101 kPa. The absorption kinetics data were developed and analyzed using the base‐catalyzed hydration mechanism and artificial neural network models (radial basis function neural network [RBFNN] and back‐propagation neural network [BPNN] models) with an acceptable absolute average deviation of 10% for base‐catalyzed hydration mechanism, 2.6% for RBFNN model and 1.77% for BPNN model, respectively. The CO2 absorption heat of 1DEA2P was estimated to be −43.6 kJ/mol. In addition, the ions (1DEA2P, 1DEA2PH+,
, CO32−) speciation plots of the 1DEA2P‐CO2‐H2O system were developed to further understand the reaction process of 1DEA2P with CO2. Based on a comparison with conventional amines (e.g., MEA, DEA, MDEA) and alternative amines (i.e., 1DMA2P and 4‐(diethylamino)−2‐butanol [DEAB]), 1DEA2P exhibited good performance with respect to CO2 equilibrium solubility, reaction kinetics, and CO2 absorption heat. Meanwhile, the overall evaluation of 1DEA2P for application in CCS in terms of absorption and desorption is presented, giving helpful information for the screening of these novel amines. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2694–2704, 2017
Cytokine therapy‐mediated neuroprotection in a Friedreich's ataxia mouse model
Authors: Kemp Kevin C. , Cerminara Nadia , Hares Kelly , Redondo Juliana , Cook Amelia J. , Haynes Harry R. , Burton Bronwen R. , Pook Mark , Apps Richard , Scolding Neil J. , Wilkins Alastair
Published: December 2016

Objectives

Friedreich's ataxia is a devastating neurological disease currently lacking any proven treatment. We studied the neuroprotective effects of the cytokines, granulocyte‐colony stimulating factor (G‐CSF) and stem cell factor (SCF) in a humanized murine model of Friedreich's ataxia.

Methods

Mice received monthly subcutaneous infusions of cytokines while also being assessed at monthly time points using an extensive range of behavioral motor performance tests. After 6 months of treatment, neurophysiological evaluation of both sensory and motor nerve conduction was performed. Subsequently, mice were sacrificed for messenger RNA, protein, and histological analysis of the dorsal root ganglia, spinal cord, and cerebellum.

Results

Cytokine administration resulted in significant reversal of biochemical, neuropathological, neurophysiological, and behavioural deficits associated with Friedreich's ataxia. Both G‐CSF and SCF had pronounced effects on frataxin levels (the primary molecular defect in the pathogenesis of the disease) and a regulators of frataxin expression. Sustained improvements in motor coordination and locomotor activity were observed, even after onset of neurological symptoms. Treatment also restored the duration of sensory nerve compound potentials. Improvements in peripheral nerve conduction positively correlated with cytokine‐induced increases in frataxin expression, providing a link between increases in frataxin and neurophysiological function. Abrogation of disease‐related pathology was also evident, with reductions in inflammation/gliosis and increased neural stem cell numbers in areas of tissue injury.

Interpretation

These experiments show that cytokines already clinically used in other conditions offer the prospect of a novel, rapidly translatable, disease‐modifying, and neuroprotective treatment for Friedreich's ataxia. Ann Neurol 2017;81:212–226
Tract‐specific atrophy in focal epilepsy: Disease, genetics, or seizures?
Authors: Vaughan David N. , Raffelt David , Curwood Evan , Tsai Meng‐Han , Tournier Jacques‐Donald , Connelly Alan , Jackson Graeme D.
Published: December 2016

Objective

To investigate whether genetics, underlying pathology, or repeated seizures contribute to atrophy in specific white matter tracts.

Methods

Medically refractory unilateral temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS‐TLE, n = 26) was studied as an archetype of focal epilepsy, using fixel‐based analysis of diffusion‐weighted imaging. A genetic effect was assessed in first‐degree relatives of HS‐TLE subjects who did not have epilepsy themselves (HS‐1°Rel; n = 26). The role of disease process was uncovered by comparing HS‐TLE to unilateral TLE with normal clinical magnetic resonance imaging (MRI‐neg TLE; n = 26, matched for seizure severity). The effect of focal seizures was inferred from lateralized atrophy common to both HS‐TLE and MRI‐neg TLE, in comparison to healthy controls (n = 76).

Results

HS‐1 °Rel had bilaterally small hippocampi, but no focal white matter atrophy was detected, indicating a limited effect of genetics. HS‐TLE subjects had lateralized atrophy of most temporal lobe tracts, and hippocampal volumes in HS‐TLE correlated with parahippocampal cingulum and anterior commissure atrophy, indicating an effect of the underlying pathology. Ipsilateral atrophy of the tapetum, uncinate, and inferior fronto‐occipital fasciculus was found in both HS‐TLE and MRI‐neg TLE, suggesting a common lateralized effect of focal seizures. Both epilepsy groups had bilateral atrophy of the dorsal cingulum and corpus callosum fibers, which we interpret as a consequence of bilateral insults (potentially generalized seizures and/or medications).

Interpretation

Underlying pathology, repeated focal seizures, and global insults each contribute to atrophy in specific tracts. Genetic factors make less of a contribution in this cohort. A multifactorial model of white matter atrophy in focal epilepsy is proposed. Ann Neurol 2017;81:240–250
Buying environmental problems: The invasive potential of imported freshwater turtles in Argentina
Authors: Nori Javier , Tessarolo Geiziane , Ficetola Gentile F. , Loyola Rafael , Di Cola Valeria , Leynaud Gerardo
Published: December 2016

In recent years, decision‐makers in Argentina have allowed the legal import of thousands of specimens of freshwater turtles. Given their invasive potential, many of the imported species have become established and have spread to other countries.

The three most commonly imported species recently have beenGraptemys pseudogeographica,Trachemys scripta, andPseudemys nelsoni, all of them native to North America.

This study assessed the invasive potential of these species in Argentina based on (i) bioclimatic envelope models, (ii) distribution of water bodies, (iii) location of the most populated cities, (iv) comparisons between their alien and native climatic niches, and (v) the main ecological traits of those species.

The results showed that these species are able to establish viable populations in Argentina, especiallyT. scriptaandG. pseudogeographica. This is because the country offers a large amount of suitable climatic space for these species, in which there are large areas with rivers and other water bodies. The situation is especially problematic in freshwater ecosystems of the north east, as well as in the most populated portion of the country.

A range of regulatory policies are suggested, which could help to reduce biodiversity loss and economic impacts in the future.
Leiopathes glaberrima millennial forest from SW Sardinia as nursery ground for the small spotted catshark Scyliorhinus canicula
Authors: Cau Alessandro , Follesa Maria Cristina , Moccia Davide , Bellodi Andrea , Mulas Antonello , Bo Marzia , Canese Simonepietro , Angiolillo Michela , Cannas Rita
Published: December 2016

Association between habitat structuring organisms and other species has great relevance for ecosystem‐based conservation measures.

Those occurring in temperate areas, particularly in the upper portion of the continental margin, are mostly unknown or not properly understood because of the difficulty to discriminate co‐occurrence and real functional linkages among species.

Deep water coral assemblages over the Carloforte Shoal (south‐west Sardinia; 180–210 m depth) were investigated using ROV surveys.

During the surveys, more than 740 egg‐capsules of the spotted catshark Scyliorhinus canicula, identified after hatching experiments in captivity, were found attached exclusively to colonies of the long‐living black coral Leiopathes glaberrima.

Although based on a spot finding, the results show that coral forests are not only hotspots of biodiversity, but can also serve as nursery grounds for S. canicula. The protection of these millennial coral forests is therefore to be considered a priority.
Rare copy number variants in a population‐based investigation of hypoplastic right heart syndrome
Authors: Dimopoulos Aggeliki , Sicko Robert J. , Kay Denise M. , Rigler Shannon L. , Druschel Charlotte M. , Caggana Michele , Browne Marilyn L. , Fan Ruzong , Romitti Paul A. , Brody Lawrence C. , Mills James L.
Published: December 2016

Background

Hypoplastic right heart syndrome (HRHS) is a rare congenital defect characterized by underdevelopment of the right heart structures commonly accompanied by an atrial septal defect. Familial HRHS reports suggest genetic factor involvement. We examined the role of copy number variants (CNVs) in HRHS.

Methods

We genotyped 32 HRHS cases identified from all New York State live births (1998–2005) using Illumina HumanOmni2.5 microarrays. CNVs were called with PennCNV and prioritized if they were ≥20 Kb, contained ≥10 SNPs and had minimal overlap with CNVs from in‐house controls, the Database of Genomic Variants, HapMap3, and Childrens Hospital of Philadelphia database.

Results

We identified 28 CNVs in 17 cases; several encompassed genes important for right heart development. One case had a 2p16‐2p23 duplication spanning LBH, a limb and heart development transcription factor. Lbh mis‐expression results in right ventricular hypoplasia and pulmonary valve defects. This duplication also encompassed SOS1, a factor associated with pulmonary valve stenosis in Noonan syndrome. Sos1−/− mice display thin and poorly trabeculated ventricles. In another case, we identified a 1.5 Mb deletion associated with Williams‐Beuren syndrome, a disorder that includes valvular malformations. A third case had a 24 Kb deletion upstream of the TGFβ ligand ITGB8. Embryos genetically null for Itgb8, and its intracellular interactant Band 4.1B, display lethal cardiac phenotypes.

Conclusion

To our knowledge, this is the first study of CNVs in HRHS. We identified several rare CNVs that overlap genes related to right ventricular wall and valve development, suggesting that genetics plays a role in HRHS and providing clues for further investigation. Birth Defects Research 109:16–26, 2017. © 2016 Wiley Periodicals, Inc.
Developmental toxicity studies of lumefantrine and artemether in rats and rabbits
Authors: Clark Robert L. , Youreneff Maureen , DeLise Anthony M.
Published: December 2016

The combination of artemether plus lumefantrine is a type of artemisinin‐based combination therapy (ACT) recommended by the World Health Organization for uncomplicated falciparum malaria except in the first trimester of pregnancy. The first trimester restriction was based on the marked embryotoxicity in animals (including embryo death and cardiac and skeletal malformations) of artemisinins such as artesunate, dihydroartemisinin, and artemether. Before recommending ACTs for use in the first trimester, the World Health Organization has requested that all information relevant to the assessment of risk of ACTs to the embryo be made available to the public. This report describes the results of embryo‐fetal development studies of artemether alone, lumefantrine alone, and the combination in rats and rabbits as well as toxicokinetic studies of lumefantrine in pregnant rabbits. The developmental no‐effect levels for lumefantrine were 300 mg/kg/day in rats (based on a 25% decrease in litter size at 1000 mg/kg/day) and 1000 mg/kg/day in rabbits. The calculated safety margins based on human equivalent dose and plasma Cmax and AUC values were in the range of 2.5‐ to 17‐fold. The developmental no‐effect levels for artemether were 3 mg/kg/day in rats and 25 mg/kg/day in rabbits. Lumefantrine caused no teratogenicity and was not a potent embryotoxin in rats and rabbits. Expected artemisinin‐like findings were seen with artemether alone and with artemether/lumefantrine combined except that no malformations were observed. There were no findings in pregnant rats and rabbits that would cause increased concern for the use of artemether–lumefantrine in the first trimester compared to other ACTs.
Zebrafish adult pigment stem cells are multipotent and form pigment cells by a progressive fate restriction process
Authors: Kelsh Robert N. , Sosa Karen C. , Owen Jennifer P. , Yates Christian A.
Published: December 2016

Skin pigment pattern formation is a paradigmatic example of pattern formation. In zebrafish, the adult body stripes are generated by coordinated rearrangement of three distinct pigment cell‐types, black melanocytes, shiny iridophores and yellow xanthophores. A stem cell origin of melanocytes and iridophores has been proposed although the potency of those stem cells has remained unclear. Xanthophores, however, seemed to originate predominantly from proliferation of embryonic xanthophores. Now, data from Singh et al. shows that all three cell‐types derive from shared stem cells, and that these cells generate peripheral neural cell‐types too. Furthermore, clonal compositions are best explained by a progressive fate restriction model generating the individual cell‐types. The numbers of adult pigment stem cells associated with the dorsal root ganglia remain low, but progenitor numbers increase significantly during larval development up to metamorphosis, likely via production of partially restricted progenitors on the spinal nerves.
Highly fluorescent au nanoclusters: Electrostatically induced phase transfer synthesis for Cu2+ sensing
Authors: Chen Qiansi , Li Yajuan , Xu Shenghao , Tie Weiwei , Wang Nan , He Zhanhang , Liu Pingping , Zhou Huina
Published: December 2016

This paper reports a convenient method for the synthesis of highly fluorescent Au nanoclusters (NCs) via electrostatically induced phase transfer. Furthermore, on the basis of an aggregation‐induced fluorescence quenching mechanism, the potential application for Cu2+ sensing on the fluorescence emission of the Au NCs is discussed. These prepared fluorescent Au NCs offer acceptable sensitivity, high selectivity, and a limit of quantitation of 0.02 μM for the measurement of Cu2+, which is lower than the maximum level (1 ppm, equals to 15.6 μM) of Cu2+ permitted in drinking water in China. This study contributes to the further development of practical applications with fluorescent NCs.
Tools of pathway reconstruction and production of economically relevant plant secondary metabolites in recombinant microorganisms
Authors: Dziggel Clarissa , Schäfer Holger , Wink Michael
Published: December 2016

Plant secondary metabolites exhibit a variety of biological activities and therefore serve as valuable therapeutics or flavoring compounds. However, the small amounts isolated from plants often cannot meet market demands. This led to the exploration of other, more profitable methods for their production, including plant cell culture systems, chemical synthesis and biotechnological production in microbial hosts. The biotechnological production can be pursued by reconstructing metabolic pathways in selected microbial systems. But due to their complexity, most of these pathways are not completely understood and require the expression of a multitude of genes in a foreign organism. Recently, next generation sequencing data and advances in gene silencing in plants allowed the elucidation of some biosynthetic pathways in more detail. Thus, the de novo production of some natural products, including morphine, strictosidine, artemisinin, taxol® and resveratrol, in extensively engineered microbial hosts has become feasible. This review highlights the reconstruction of these pathways, missing pieces and novel techniques employed.
Hippocampal atrophy and memory dysfunction associated with physical inactivity in community‐dwelling elderly subjects: The Sefuri study
Authors: Hashimoto Manabu , Araki Yuko , Takashima Yuki , Nogami Kohjiro , Uchino Akira , Yuzuriha Takefumi , Yao Hiroshi
Published: December 2016

Background

Physical inactivity is one of the modifiable risk factors for hippocampal atrophy and Alzheimer's disease. We investigated the relationship between physical activity, hippocampal atrophy, and memory using structural equation modeling (SEM).

Materials and Methods

We examined 213 community‐dwelling elderly subjects (99 men and 114 women with a mean age of 68.9 years) without dementia or clinically apparent depression. All participants underwent Mini‐Mental State Examination (MMSE) and Rivermead Behavioral Memory Test (RBMT). Physical activities were assessed with a structured questionnaire. We evaluated the degree of hippocampal atrophy (z‐score—referred to as ZAdvance hereafter), using a free software program—the voxel‐based specific regional analysis system for Alzheimer's disease (VSRAD) based on statistical parametric mapping 8 plus Diffeomorphic Anatomical Registration Through an Exponentiated Lie algebra.

Results

Routine magnetic resonance imaging findings were as follows: silent brain infarction, n = 24 (11.3%); deep white matter lesions, n = 72 (33.8%); periventricular hyperintensities, n = 35 (16.4%); and cerebral microbleeds, n = 14 (6.6%). Path analysis based on SEM indicated that the direct paths from leisure‐time activity to hippocampal atrophy (β = −.18, p < .01) and from hippocampal atrophy to memory dysfunction (RBMT) (β = −.20, p < .01) were significant. Direct paths from “hippocampus” gray matter volume to RBMT and MMSE were highly significant, while direct paths from “whole brain” gray matter volume to RBMT and MMSE were not significant. The presented SEM model fit the data reasonably well.

Conclusion

Based on the present SEM analysis, we found that hippocampal atrophy was associated with age and leisure‐time physical inactivity, and hippocampal atrophy appeared to cause memory dysfunction, although we are unable to infer a causal or temporal association between hippocampal atrophy and memory dysfunction from the present observational study.
Engineered ligand‐based VEGFR antagonists with increased receptor binding affinity more effectively inhibit angiogenesis
Authors: Kapur Shiven , Silverman Adam P. , Ye Anne Z. , Papo Niv , Jindal Darren , Blumenkranz Mark S. , Cochran Jennifer R.
Published: December 2016

Pathologic angiogenesis is mediated by the coordinated action of the vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling axis, along with crosstalk contributed by other receptors, notably αvβ3 integrin. We build on earlier work demonstrating that point mutations can be introduced into the homodimeric VEGF ligand to convert it into an antagonist through disruption of binding to one copy of VEGFR2. This inhibitor has limited potency, however, due to loss of avidity effects from bivalent VEGFR2 binding. Here, we used yeast surface display to engineer a variant with VEGFR2 binding affinity approximately 40‐fold higher than the parental antagonist, and 14‐fold higher than the natural bivalent VEGF ligand. Increased VEGFR2 binding affinity correlated with the ability to more effectively inhibit VEGF‐mediated signaling, both in vitro and in vivo, as measured using VEGFR2 phosphorylation and Matrigel implantation assays. High affinity mutations found in this variant were then incorporated into a dual‐specific antagonist that we previously designed to simultaneously bind to and inhibit VEGFR2 and αvβ3 integrin. The resulting dual‐specific protein bound to human and murine endothelial cells with relative affinities of 120 ± 10 pM and 360 ± 50 pM, respectively, which is at least 30‐fold tighter than wild‐type VEGF (3.8 ± 0.5 nM). Finally, we demonstrated that this engineered high‐affinity dual‐specific protein could inhibit angiogenesis in a murine corneal neovascularization model. Taken together, these data indicate that protein engineering strategies can be combined to generate unique antiangiogenic candidates for further clinical development.