bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical/thermal sensitivity and superficial temperature in the stump of long-term tail-docked dairy cows
Authors: Troncoso Renata J , Herzberg Daniel E , Meneses Constanza S , Müller Heine Y , Werner Marianne P , Bustamante Hedie
Published: February 2018

Background. Tail docking of dairy cows is a painful procedure that affects animal welfare. The aims of this study were first to evaluate the response to mechanical and thermal stimulation, and second to determine the superficial temperature of the stump of tail-docked dairy cows. Methods. One hundred and sixty four dairy cows were enrolled. From these, 133 cows were assigned to the tail-docked group (TD) and 31 cows were selected as control animals (C). The following sensory assessments to evaluate pain in tail-docked cows were performed. Sensitivity of the tail region in both groups of animals was evaluated using a portable algometer. Cold and heat sensitivity assessment was performed using a frozen pack (0ºC) and warm water (45ºC), respectively. Pinprick sensitivity was evaluated using a Wartenberg neurological pinwheel. Superficial temperature was evaluated using a thermographic camera. All sensory assessments and superficial temperature were evaluated in the ventral surface of the tail stump (TD) and tail (C). Results. Analysis revealed a significant effect of condition on the pressure pain threshold with significantly lower values necessary to obtain a withdrawal response in TD cows (5.97±0.19 kg) compared to C cows (11.75±0.43 kg). Chi Square test revealed that there was a significant association between heat sensitivity and condition with 29.3% of TD cows responding positively. Nonetheless, no association was found between condition and cold sensitivity. Similarly, after pinprick sensitivity test was performed, 93.2% of TD cows elicited a positive response to stimulation. This sensory testing was significantly associated with the condition. There was a significant effect of condition on superficial temperature, where TD cows had significantly lower temperature (26.43±0.27 ºC) when compared to C animals (29.86±0.62 ºC). Discussion. Pressure pain threshold values in both groups of animals were higher that those previously reported for tail docked pigs, sows and cows. In contrast, pinprick stimulation evaluates the presence of punctate mechanical hyperalgesia/allodynia, usually related to traumatic nerve injury, and this association may reveal that it is possible that these animals developed a disorder associated to the development of a tail stump neuroma and concurrent neuropathic pain, previously reported in tail-docked lambs, pigs and dogs. Thermal sensitivity showed that tail-docked cows responded positively only to heat stimulation. These findings suggest that long-term tail-docked cows could be suffering hyperalgesia/allodynia, which may be indicative of chronic pain. Lower superficial temperature in the stump may be associated to sympathetic fiber sprouting in the distal stump, which can lead to vasoconstriction and lower surface temperatures. Further studies are needed in order to confirm neuroma development and adrenergic sprouting.
A quantitative study of blood circulation in the developing adult ascidian tunicate Ciona savignyi (Cionidae).
Authors: Konrad Michael W
Published: February 2018

Development of the adult ascidian tunicate starts when the tadpole larvae attaches to a surface. In approximately two days the solid tadpole will metamorphose into two joined concentric hollow cylinders. The outer cylinder is the body and the inner cylinder is the branchial basket containing openings (stigmata) lined with cilia that pump water through a mucus net that traps food. In six days a heart and circulatory system has formed and blood is pumped through the branchial basket and a smaller visceral cavity containing the heart, stomach, intestine, and gonads. At this stage the animal is quite transparent and moving blood cells are easily distinguished from the fixed cell network of the animal body. The human eye-brain is good at identifying moving cells, but the area of high resolution is limited as is the ability to remember multiple events. However, sequential video frames obtained using a consumer grade camera mounted on a low power microscope, contains the information needed to identify and document moving cells using free open source software described in this report. Subtraction of sequential frames results in a blank difference image if the frames are the same, but produces positive-negative image pairs of cells that have moved during the frame interval. The collection of many sequential difference images thus produces a map of the circulatory system. At six days the circulatory system consists of two perpendicular loops. The larger longitudinal (sagittal) loop runs from the heart along the ventral edge of the branchial basket to a loop around the oral siphon, then back along the dorsal edge of the basket, through three branches in the small visceral cavity, and returns to the heart. One or more transverse loop(s) transports blood from the ventral to the dorsal vessel across the sides of the branchial basket and around the stigmata. Blood cells traverse the longitudinal loop in about 11 sec. As the tunicate matures the number of stigmata increases and the transverse loops develop branches. The branch points then migrate to the dorsal and ventral vessels to form a series of parallel transverse vessels. In the brachial basket blood cells move in both transverse and longitudinal direction around the stigmata.
A dynamic mechanism for allosteric activation of Aurora kinase A by activation loop phosphorylation
Authors: Ruff Emily F , Muretta Joseph M , Thompson Andrew R , Lake Eric W , Cyphers Soreen , Albanese Steven K , Hanson Sonya M , Behr Julie M , Thomas David D , Chodera John D , Levinson Nicholas M
Published: February 2018

Many eukaryotic protein kinases are activated by phosphorylation on a specific conserved residue in the regulatory activation loop, a post-translational modification thought to stabilize the active DFG-In state of the catalytic domain. Here we use a battery of spectroscopic methods that track different catalytic elements of the kinase domain to show that the ~100 fold activation of the mitotic kinase Aurora A (AurA) by phosphorylation occurs without a population shift from the DFG-Out to the DFG-In state, and that the activation loop of the activated kinase remains highly dynamic. Instead, molecular dynamics simulations and electron paramagnetic resonance experiments show that phosphorylation triggers a switch within the DFG-In subpopulation from an autoinhibited DFG-In substate to an active DFG-In substate, leading to catalytic activation. This mechanism raises new questions about the functional role of the DFG-Out state in protein kinases.
On the move
Authors: Martin Sandra L
Published: February 2018

The mechanisms by which a retrotransposon called LINE-1 duplicates itself and spreads through the human genome are becoming clearer.
Repeatability of glucocorticoid hormones in vertebrates: a meta-analysis
Authors: Schoenemann Kelsey L. , Bonier Frances
Published: February 2018

We often expect that investigations of the patterns, causes, and consequences of among-individual variation in a trait of interest will reveal how selective pressures or ecological conditions influence that trait. However, many endocrine traits, such as concentrations of glucocorticoid (GC) hormones, exhibit adaptive plasticity and, therefore, do not necessarily respond to these pressures as predicted by among-individual phenotypic correlations. To improve our interpretations of among-individual variation in GC concentrations, we need more information about the repeatability of these traits within individuals. Many studies have already estimated the repeatability of baseline, stress-induced, and integrated GC measures, which provides an opportunity to use meta-analytic techniques to investigate (1) whether GC titers are generally repeatable across taxa, and (2) which biological or methodological factors may impact these estimates. From an intensive search of the literature, we collected 91 GC repeatability estimates from 47 studies. Overall, we found evidence that GC levels are repeatable, with mean repeatability estimates across studies ranging from 0.230 for baseline levels to 0.386 for stress-induced levels. We also noted several factors that predicted the magnitude of these estimates, including taxon, sampling season, and lab technique. Amphibians had significantly higher repeatability in baseline and stress-induced GCs than birds, mammals, reptiles, or bony fish. The repeatability of stress-induced GCs was higher when measured within, rather than across, life history stages. Finally, estimates of repeatability in stress-induced and integrated GC measures tended to be lower when GC concentrations were quantified using commercial kit assays rather than in-house assays. The extent to which among-individual variation in GCs may explain variation in organismal performance or fitness (and thereby inform our understanding of the ecological and evolutionary processes driving that variation) depends on whether measures of GC titers accurately reflect how individuals differ overall. Our findings suggest that while GC titers can reflect some degree of consistent differences among individuals, they frequently may not. We discuss how our findings contribute to interpretations of variation in GCs, and suggest routes for the design and analysis of future research.
Revisited analysis of a SHIVA01 trial cohort using functional mutational analyses successfully predicted treatment outcome
Authors: Kamal Maud , Tarcic Gabi , Dureau Sylvain , Edelheit Oded , Barbash Zohar , Lecerf Charlotte , Morel Claire , Miron Benjamin , Callens Celine , Servant Nicolas , Bieche Ivan , Vidne Michael , Le Tourneau Christophe
Published: February 2018

It still remains to be demonstrated that using molecular profiling to guide therapy improves patient outcome in oncology. Classification of somatic variants is not straightforward, rendering treatment decisions based on variants with unknown significance (VUS) hard to implement. The oncogenic activity of VUS and mutations identified in 12 patients treated with molecularly targeted agents (MTAs) in the frame of SHIVA01 trial was assessed using Functional Annotation for Cancer Treatment (FACT). MTA response prediction was measured in vitro, blinded to the actual clinical trial results, and survival predictions according to FACT were correlated with the actual PFS of SHIVA01 patients. Patients with positive prediction had a median PFS of 5.8 months versus 1.7 months in patients with negative prediction (P < 0.05). Our results highlight the role of the functional interpretation of molecular profiles to predict MTA response.
Inferences of individual drug responses across diverse cancer types using a novel competing endogenous RNA network
Authors: Zhang Yan , Li Xin , Zhou Dianshuang , Zhi Hui , Wang Peng , Gao Yue , Guo Maoni , Yue Ming , Wang Yanxia , Shen Weitao , Ning Shangwei , Li Yixue , Li Xia
Published: February 2018

Differences in individual drug responses are an obstacle to progression in cancer treatment, and predicting responses would help to plan treatment. The accumulation of cancer molecular profiling and drug response data provides opportunities and challenges to identify novel molecular signatures and mechanisms of tumor responsiveness to drugs. This study evaluated drug responses with a competing endogenous RNA (ceRNA) system that depended on competition between diverse RNA species. We identified drug response‐related ceRNA (DRCEs) by combining the sequence and expression data of long noncoding RNA (lncRNA), microRNA (miRNA), and messenger RNA (mRNA), and the survival data of cancer patients treated with drugs. We constructed a patient–drug two‐layer integrated network and used a linear weighting method to predict individual drug responses. DRCEs were found to be significantly enriched in known cancer and drug‐associated data resources, involved in biological processes known to mediate drug responses, and correlated to drug activity in cancer cell lines. The dysregulation of DRCE expression influenced drug response‐associated functions and pathways, suggesting DRCEs as potential therapeutic targets affecting drug responses. A further case study in breast invasive carcinoma (BRCA) found that DRCE expression was consistent with the drug response pattern and the aberrant expression of the two NEAT1‐related DRCEs may lead to poor response to tamoxifen therapy for patients with TP53 mutations. In summary, this study provides a framework for ceRNA‐based evaluation of clinical drug responses across multiple cancer types. Understanding the underlying molecular mechanisms of drug responses will allow improved response to chemotherapy and outcomes of cancer treatment.
Understanding the Changes in Global Crop Yields Through Changes in Climate and Technology
Authors: Najafi Ehsan , Devineni Naresh , Khanbilvardi Reza M. , Kogan Felix
Published: February 2018

During the last few decades, the global agricultural production has risen and technology enhancement is still contributing to yield growth. However, population growth, water crisis, deforestation, and climate change threaten the global food security. An understanding of the variables that caused past changes in crop yields can help improve future crop prediction models. In this article, we present a comprehensive global analysis of the changes in the crop yields and how they relate to different large‐scale and regional climate variables, climate change variables and technology in a unified framework. A new multilevel model for yield prediction at the country level is developed and demonstrated. The structural relationships between average yield and climate attributes as well as trends are estimated simultaneously. All countries are modeled in a single multilevel model with partial pooling to automatically group and reduce estimation uncertainties. El Niño‐southern oscillation (ENSO), Palmer drought severity index (PDSI), geopotential height anomalies (GPH), historical carbon dioxide (CO2) concentration and country‐based time series of GDP per capita as an approximation of technology measurement are used as predictors to estimate annual agricultural crop yields for each country from 1961 to 2013. Results indicate that these variables can explain the variability in historical crop yields for most of the countries and the model performs well under out‐of‐sample verifications. While some countries were not generally affected by climatic factors, PDSI and GPH acted both positively and negatively in different regions for crop yields in many countries.
Responses of Solar Irradiance and the Ionosphere to an Intense Activity Region
Authors: Chen Yiding , Liu Libo , Le Huijun , Wan Weixing
Published: February 2018

Solar rotation (SR) variation dominates solar extremely ultraviolet (EUV) changes on the timescale of days. The F10.7 index is usually used as an indicator for solar EUV. The SR variation of F10.7 significantly enhanced during the 2008th–2009th Carrington rotations (CRs) owing to an intense active region; F10.7 increased about 180 units during that SR period. That was the most prominent SR variation of F10.7 during solar cycle 23. In this paper, global electron content (GEC) is used to investigate ionospheric response to that strong variation of solar irradiance indicated by F10.7. The variation of GEC with F10.7 was anomalous (GEC‐F10.7 slope significantly decreased) during the 2008th–2009th CRs; however, GEC versus EUV variation during that period was consistent with that during adjacent time intervals when using Solar Heliospheric Observatory/Solar EUV Monitor 26–34 nm EUV measurements. The reason is that F10.7 response to that intense active region was much stronger than EUV response; thus, the EUV‐F10.7 slope decreased. We confirmed decreased EUV‐F10.7 slope during the 2008th–2009th CRs for different wavelengths within 27–120 nm using Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Solar EUV Experiment high spectral resolution EUV measurements. And on the basis of Solar Heliospheric Observatory/Solar EUV Monitor EUV measurements during solar cycle 23, we further presented that EUV‐F10.7 slope statistically tends to decrease when the SR variation of F10.7 significantly enhances. Moreover, we found that ionospheric time lag effect to EUV is exaggerated when using F10.7, owing to the time lag effect of EUV to F10.7.
Effect of Southern Hemisphere Sudden Stratospheric Warmings on Antarctica Mesospheric Tides: First Observational Study
Authors: Eswaraiah S. , Kim Yong Ha , Lee Jaewook , Ratnam M. Vankat , Rao S. V. B.
Published: February 2018

We analyzed the structure and variability of observed winds and tides in the Antarctica mesosphere and lower thermosphere (MLT) during the 2002 major sudden stratospheric warming (SSW) and the 2010 minor SSWs. We noted the effect of SSW on the variability of MLT tides for the first time in the Southern Hemisphere, although it has been well recognized in the Northern Hemisphere. We utilized the winds measured by Rothera (68°S, 68°W) medium frequency radar and King Sejong Station (62.22°S, 58.78°W) meteor radar for estimating the tidal components (diurnal, semi‐diurnal, and ter‐diurnal) in the MLT region. The unusual behavior of diurnal tide (DT) and semidiurnal tide (SDT) was observed in 2002. Zonal SDT amplitudes were enhanced up to 27 m/s after 18 days from the associated SSW day. However, the meridional tidal amplitudes of both DT and SDT suddenly decreased during the peak SSW, and SDT amplitudes slightly increased to 18 m/s afterward. In the normal years, SDT amplitude stays below 15 m/s. During the 2010 SSW, SDT zonal amplitudes increased up to 40 m/s and 50 m/s at altitudes of 80 km and 90 km, respectively, ~30 days after the associated SSW. Similar but weaker effect is noticed in the meridional components. The ter‐diurnal tide does not show any significant variation during the SSW. The two SSWs offered a challenging issue to answer: why tidal amplitudes are enhanced with a delay after the SSW. The reasons for the delay are discussed in accordance with theoretical predictions.
An Inverse Model for Estimating the Optical Absorption and Backscattering Coefficients of Seawater From Remote‐Sensing Reflectance Over a Broad Range of Oceanic and Coastal Marine Environments
Authors: Loisel Hubert , Stramski Dariusz , Dessailly David , Jamet Cédric , Li Linhai , Reynolds Rick A.
Published: February 2018

We present an inverse model (referred to as LS2) for estimating the inherent optical properties (IOPs) of seawater, specifically the spectral absorption, a(λ), and backscattering, bb(λ), coefficients within the ocean surface layer, from measurements of ocean remote‐sensing reflectance, Rrs(λ). The nonwater absorption, anw(λ), and particulate backscattering, bbp(λ), coefficients can be derived after subtracting pure seawater contributions. The LS2 requires no spectral assumptions about IOPs and provides solutions at arbitrary light wavelengths in the visible spectrum independently of one another. As the LS2 can operate with the inputs of Rrs(λ) and solar zenith angle it is applicable to satellite ocean color remote sensing. The model can also operate with additional input of the diffuse attenuation coefficient of downward irradiance, which provides somewhat improved model performance for applications using in situ radiometric measurements as inputs. The evaluation of LS2 with a synthetic data set that is free of measurement errors indicates good performance for IOPs in the visible spectrum, except for anw(λ) in the long‐wavelength portion of the spectrum where anw(λ) contributes only a few percent to a(λ) under typical open ocean conditions. The good performance is characterized by a median absolute percent difference between the model‐derived and true values of IOPs, which is generally <20%, and the median ratio of model‐derived to true values <10%. The satisfactory model performance is also demonstrated through validation analysis based on extensive data sets comprising coincident in situ measurements of Rrs(λ) and IOPs as well as a match‐up data set comprising satellite‐derived Rrs(λ) and in situ IOP measurements.
Influence of Emissions and Aqueous Processing on Particles Containing Black Carbon in a Polluted Urban Environment: Insights From a Soot Particle‐Aerosol Mass Spectrometer
Authors: Collier Sonya , Williams Leah R. , Onasch Timothy B. , Cappa Christopher D. , Zhang Xiaolu , Russell Lynn M. , Chen Chia‐Li , Sanchez Kevin J. , Worsnop Douglas R. , Zhang Qi
Published: February 2018

Inorganic and organic coatings on black carbon (BC) particles can enhance light absorption and affect atmospheric lifetimes of BC‐containing particles and thus have significant implications for climate. To study the physical and chemical characteristics of atmospheric BC and BC‐associated coatings, a soot particle‐aerosol mass spectrometer was deployed during the winter of 2014–2015 in Fresno, a city located in the San Joaquin Valley of California, to selectively analyze BC‐containing particles. Comparing soot particle‐aerosol mass spectrometer measurements to those from the collocated single‐particle soot photometer (SP2) and high‐resolution aerosol mass spectrometer, we found that 17% of total submicrometer aerosol mass was associated with BC‐containing particles, suggesting that a majority of the fine particles in Fresno contained no BC. Most BC‐containing particles appeared to be associated with residential wood burning and vehicular traffic. These particles typically had a bulk‐average mass ratio of coating to BC (Rcoat/rBC) less than 2. However, during periods of persistent fog larger Rcoat/rBC values were observed, with the coatings primarily composed of secondary inorganic and organic components that likely resulted from aqueous‐phase processing. Specifically, compared to periods with less fog, the BC coating increased in concentration and contained a larger fraction of nitrate and oxidized organic matter. The size distributions of BC and associated organic coating were generally centered around 300 nm in vacuum aerodynamic diameter. However, during foggy periods BC had an additional peak at ~400 nm and organics and nitrate displayed a prominent mode in the accumulation size range.
Influence of Western Tibetan Plateau Summer Snow Cover on East Asian Summer Rainfall
Authors: Wang Zhibiao , Wu Renguang , Chen Shangfeng , Huang Gang , Liu Ge , Zhu Lihua
Published: February 2018

The influence of boreal winter‐spring eastern Tibetan Plateau snow anomalies on the East Asian summer rainfall variability has been the focus of previous studies. The present study documents the impacts of boreal summer western and southern Tibetan Plateau snow cover anomalies on summer rainfall over East Asia. Analysis shows that more snow cover in the western and southern Tibetan Plateau induces anomalous cooling in the overlying atmospheric column. The induced atmospheric circulation changes are different corresponding to more snow cover in the western and southern Tibetan Plateau. The atmospheric circulation changes accompanying the western Plateau snow cover anomalies are more obvious over the midlatitude Asia, whereas those corresponding to the southern Plateau snow cover anomalies are more prominent over the tropics. As such, the western and southern Tibetan Plateau snow cover anomalies influence the East Asian summer circulation and precipitation through different pathways. Nevertheless, the East Asian summer circulation and precipitation anomalies induced by the western and southern Plateau snow cover anomalies tend to display similar distribution so that they are more pronounced when the western and southern Plateau snow cover anomalies work in coherence. Analysis indicates that the summer snow cover anomalies over the Tibetan Plateau may be related to late spring snow anomalies due to the persistence. The late spring snow anomalies are related to an obvious wave train originating from the western North Atlantic that may be partly associated with sea surface temperature anomalies in the North Atlantic Ocean.
Application and Evaluation of an Explicit Prognostic Cloud‐Cover Scheme in GRAPES Global Forecast System
Authors: Ma Zhanshan , Liu Qijun , Zhao Chuanfeng , Shen Xueshun , Wang Yuan , Jiang Jonathan H. , Li Zhe , Yung Yuk
Published: February 2018

An explicit prognostic cloud‐cover scheme (PROGCS) is implemented into the Global/Regional Assimilation and Prediction System (GRAPES) for global middle‐range numerical weather predication system (GRAPES_GFS) to improve the model performance in simulating cloud cover and radiation. Unlike the previous diagnostic cloud‐cover scheme (DIAGCS), PROGCS considers the formation and dissipation of cloud cover by physically connecting it to the cumulus convection and large‐scale stratiform condensation processes. Our simulation results show that clouds in mid‐high latitudes arise mainly from large‐scale stratiform condensation processes, while cumulus convection and large‐scale condensation processes jointly determine cloud cover in low latitudes. Compared with DIAGCS, PROGCS captures more consistent vertical distributions of cloud cover with the observations from Atmospheric Radiation Measurements (ARM) program at the Southern Great Plains (SGP) site and simulates more realistic diurnal cycle of marine stratocumulus with the ERA‐Interim reanalysis data. The low, high, and total cloud covers that are determined via PROGCS appear to be more realistic than those simulated via DIAGCS when both are compared with satellite retrievals though the former maintains slight negative biases. In addition, the simulations of outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) from PROGCS runs have been considerably improved as well, resulting in less biases in radiative heating rates at heights below 850 hPa and above 400 hPa of GRAPES_GFS. Our results indicate that a prognostic method of cloud‐cover calculation has significant advantage over the conventional diagnostic one, and it should be adopted in both weather and climate simulation and forecast.
Using Extreme Value Theory for Determining the Probability of Carrington‐Like Solar Flares
Authors: Elvidge S. , Angling M. J.
Published: February 2018

By their very nature, extreme space weather events occur rarely, and therefore, statistical methods are required to determine the probability of their occurrence. Space weather events can be characterized by a number of natural phenomena such as X‐ray (solar) flares, solar energetic particle fluxes, coronal mass ejections, and various geophysical indices (such as Dst, Kp, and F10.7). In this paper extreme value theory (EVT) is used to investigate the probability of extreme solar flares. Previous work has assumed that the distribution of solar flares follows a power law. However, such an approach can lead to a poor estimation of the return times of flares due to uncertainties in the tails of the probability distribution function. Using EVT and Geostationary Operational Environmental Satellites X‐ray flux data, it is shown that the expected 150 year return level is approximately an X60 flare while a Carrington‐like flare is a one in a 100 year event. In the worst case the 150 year return level is an X90 flare while a Carrington flare is a one in 30 year event. It is also shown that the EVT results are consistent with flare data from the Kepler space telescope mission.
The Radial Propagation Characteristics of the Injection Front: A Statistical Study Based On BD‐IES and Van Allen Probes Observations
Authors: Liu Z. Y. , Zong Q.‐G. , Hao Y. X. , Liu Y. , Chen X.‐R.
Published: February 2018

Electron flux measurements outside geosynchronous orbit (GSO) obtained by the BeiDa Imaging Electron Spectrometer instrument on board a 55° inclined GSO satellite and inside GSO obtained by the Van Allen Probes are analyzed to investigate the temporal and spatial evolutions of the substorm injection region. In 1 year data started from October 2015, 63 injection events are identified. First, our study shows that the injection signatures can be detected in a large radial extent in one single event, for example, from L ∼ 4.1 to L ∼ 9.3. Second, injection onset times are derived from the energy dispersion of particle injection signatures of each satellite. The difference of the onset times among satellites reveals that the injection boundary, termed as “injection front” in this paper, can propagate both earthward and tailward with a speed varying from a few km/s to ∼100 km/s. Third, evolutions of the upper‐cutoff magnetic moments (μuc) of injected electrons are analyzed, upon which the injection events are classified into two categories. In one category, the μuc observed by two radially separated satellites are equal taking into account the error caused by the finite width of energy channels, whereas in the other category, μuc at lower L shells are smaller than those at higher L shells.
Evaluation of the WRF‐Urban Modeling System Coupled to Noah and Noah‐MP Land Surface Models Over a Semiarid Urban Environment
Authors: Salamanca Francisco , Zhang Yizhou , Barlage Michael , Chen Fei , Mahalov Alex , Miao Shiguang
Published: February 2018

We have augmented the existing capabilities of the integrated Weather Research and Forecasting (WRF)‐urban modeling system by coupling three urban canopy models (UCMs) available in the WRF model with the new community Noah with multiparameterization options (Noah‐MP) land surface model (LSM). The WRF‐urban modeling system's performance has been evaluated by conducting six numerical experiments at high spatial resolution (1 km horizontal grid spacing) during a 15 day clear‐sky summertime period for a semiarid urban environment. To assess the relative importance of representing urban surfaces, three different urban parameterizations are used with the Noah and Noah‐MP LSMs, respectively, over the two major cities of Arizona: Phoenix and Tucson metropolitan areas. Our results demonstrate that Noah‐MP reproduces somewhat better than Noah the daily evolution of surface skin temperature and near‐surface air temperature (especially nighttime temperature) and wind speed. Concerning the urban areas, bulk urban parameterization overestimates nighttime 2 m air temperature compared to the single‐layer and multilayer UCMs that reproduce more accurately the daily evolution of near‐surface air temperature. Regarding near‐surface wind speed, only the multilayer UCM was able to reproduce realistically the daily evolution of wind speed, although maximum winds were slightly overestimated, while both the single‐layer and bulk urban parameterizations overestimated wind speed considerably. Based on these results, this paper demonstrates that the new community Noah‐MP LSM coupled to an UCM is a promising physics‐based predictive modeling tool for urban applications.
High Entropy Alloys: Prospective Materials for Tribo‐Corrosion Applications
Authors: Nair Rakesh Bhasakaran , Arora Harpreet Singh , Ayyagari Aditya , Mukherjee Sundeep , Grewal Harpreet Singh
Published: February 2018

Tribo‐corrosion is an issue of concern for marine and other fluid machinery. High entropy alloys (HEAs) represent a new category of materials possessing exceptional properties. We investigated the erosion‐corrosion behavior of Al0.1CoCrFeNi HEA. For comparison, stainless steel SS316L is also evaluated. Results indicate that despite low hardness and yield strength, HEA exhibits high erosion‐corrosion resistance compared to steel. The HEA also shows high pitting and passive potentials compared to steel. The superior erosion‐corrosion resistance of HEA is due to high corrosion resistance, and work hardenability. The degradation mechanism investigated using SEM show ploughing as the primary material removal mode (MRM) for HEA at an oblique angle compared to micro‐cutting for SS316L steel. At normal impingement, platelet mechanism is observed to be the dominant MRM.
Microstructure and Mechanical Properties of Austenitic Stainless Steels after Dynamic and Post‐Dynamic Recrystallization Treatment
Authors: Tikhonova Marina , Kaibyshev Rustam , Belyakov Andrey
Published: February 2018

The effects of dynamic and post‐dynamic recrystallization (DRX and post‐DRX) on the microstructure and mechanical properties of austenitic stainless steels are critically reviewed. Particularly, the paper is focused on the grain refinement and strengthening by large strain deformation including severe plastic deformation conditions. The DRX and post‐DRX microstructures are considered with close relation to the operative recrystallization mechanisms. Specific emphasis is placed upon two recrystallization mechanisms, that is, discontinuous and continuous, and their dependence on the deformation/annealing conditions. The relationships between DRX microstructures and processing conditions are summarized and their effect on post‐DRX behavior is clarified. The structural strengthening mechanisms including the grain size and the dislocation density are elaborated.
Molybdenum Phosphide/Carbon Nanotube Hybrids as pH‐Universal Electrocatalysts for Hydrogen Evolution Reaction
Authors: Zhang Xing , Yu Xiaolu , Zhang Linjie , Zhou Feng , Liang Yongye , Wang Ruihu
Published: February 2018

Molybdenum phosphide (MoP) has received increasing attention due to its high catalytic activity in hydrogen evolution reaction (HER). However, it remains difficult to construct well‐defined MoP nanostructures with large density of active sites and high intrinsic activity. Here, a facile and general method is reported to synthesize an MoP/carbon nanotube (CNT) hybrid featuring small‐sized and well‐crystallized MoP nanoparticles uniformly coated on the sidewalls of multiwalled CNT. The MoP/CNT hybrid exhibits impressive HER activities in pH‐universal electrolytes, and requires the overpotentials as low as 83, 102, and 86 mV to achieve a cathodic current density of 10 mA cm−2 in acidic 0.5 m H2SO4, neutral 1 m phosphate buffer solution, and alkaline 1 m KOH electrolytes, respectively. It is found that the crystallinity of MoP has significant influence on HER activity. This study provides a new design strategy to construct MoP nanostructures for optimizing its catalytic performance.
1 + 1 >> 2: Dramatically Enhancing the Emission Efficiency of TPE‐Based AIEgens but Keeping their Emission Color through Tailored Alkyl Linkages
Authors: Dang Dongfeng , Qiu Zijie , Han Ting , Liu Yong , Chen Ming , Kwok Ryan T. K. , Lam Jacky W. Y. , Tang Ben Zhong
Published: February 2018

Currently, the development of aggregation‐induced emission (AIE) luminogens (AIEgens) has enabled us to “see” never before seen scenery. However, not all AIEgens exhibit the impressive emission efficiency in aggregated states. Moreover, the emission color of AIEgens can be seriously affected when their performance is improved. Therefore, to overcome this limitation, an efficient method is proposed here through the tailored alkyl linkages to greatly improve the emission efficiency of tetraphenylethene (TPE)‐based AIEgens but retain their emission color. Encouragingly, significantly enhanced emission efficiency is achieved with the quantum yield up to 68.19% and 65.20% for BTPE‐C4 and BTPE‐C8, respectively, in contrast to that of TPE (25.32%), demonstrating the proverb that one plus one is much larger than two (1 + 1 >> 2). Interestingly, when alkyl linkages in skeletons are fine‐tuned, self‐assembled nanorods, nanosheets, and nanofibers are successfully achieved for BTPE‐C1, BTPE‐C4, and BTPE‐C8 in tetrahydrofuran and water system. Also, these developed emissive AIEgens not only exhibit impressive response to the environmental stimuli of mechanical force, viscosity, temperature, and light, but can also be used to dynamically monitor and control the phase‐separated morphology in polymeric blends.
Light‐Induced Reversible Control of Ferroelectric Polarization in BiFeO3
Authors: Yang Ming‐Min , Alexe Marin
Published: February 2018

Manipulation of ferroic order parameters, namely (anti‐)ferromagnetic, ferroelectric, and ferroelastic, by light at room temperature is a fascinating topic in modern solid‐state physics due to potential cross‐fertilization in research fields that are largely decoupled. Here, full optical control, that is, reversible switching, of the ferroelectric/ferroelastic domains in BiFeO3 thin films at room temperature by the mediation of the tip‐enhanced photovoltaic effect is demonstrated. The enhanced short‐circuit photocurrent density at the tip contact area generates a local electric field well exceeding the coercive field, enabling ferroelectric polarization switching. Interestingly, by tailoring the photocurrent direction, via either tuning the illumination geometry or simply rotating the light polarization, full control of the ferroelectric polarization is achieved. The finding offers a new insight into the interactions between light and ferroic orders, enabling fully optical control of all the ferroic orders at room temperature and providing guidance to design novel optoferroic devices for data storage and sensing.
Imaging Heterogeneously Distributed Photo‐Active Traps in Perovskite Single Crystals
Authors: Yuan Haifeng , Debroye Elke , Bladt Eva , Lu Gang , Keshavarz Masoumeh , Janssen Kris P. F. , Roeffaers Maarten B. J. , Bals Sara , Sargent Edward H. , Hofkens Johan
Published: February 2018

Organic–inorganic halide perovskites (OIHPs) have demonstrated outstanding energy conversion efficiency in solar cells and light‐emitting devices. In spite of intensive developments in both materials and devices, electronic traps and defects that significantly affect their device properties remain under‐investigated. Particularly, it remains challenging to identify and to resolve traps individually at the nanoscopic scale. Here, photo‐active traps (PATs) are mapped over OIHP nanocrystal morphology of different crystallinity by means of correlative optical differential super‐resolution localization microscopy (Δ‐SRLM) and electron microscopy. Stochastic and monolithic photoluminescence intermittency due to individual PATs is observed on monocrystalline and polycrystalline OIHP nanocrystals. Δ‐SRLM reveals a heterogeneous PAT distribution across nanocrystals and determines the PAT density to be 1.3 × 1014 and 8 × 1013 cm−3 for polycrystalline and for monocrystalline nanocrystals, respectively. The higher PAT density in polycrystalline nanocrystals is likely related to an increased defect density. Moreover, monocrystalline nanocrystals that are prepared in an oxygen‐ and moisture‐free environment show a similar PAT density as that prepared at ambient conditions, excluding oxygen or moisture as chief causes of PATs. Hence, it is concluded that the PATs come from inherent structural defects in the material, which suggests that the PAT density can be reduced by improving crystalline quality of the material.
Zwitterionic Nanocages Overcome the Efficacy Loss of Biologic Drugs
Authors: Li Bowen , Yuan Zhefan , Zhang Peng , Sinclair Andrew , Jain Priyesh , Wu Kan , Tsao Caroline , Xie Jingyi , Hung Hsiang‐Chieh , Lin Xiaojie , Bai Tao , Jiang Shaoyi
Published: February 2018

For biotherapeutics that require multiple administrations to fully cure diseases, the induction of undesirable immune response is one common cause for the failure of their treatment. Covalent binding of hydrophilic polymers to proteins is commonly employed to mitigate potential immune responses. However, while this technique is proved to partially reduce the antibodies (Abs) reactive to proteins, it may induce Abs toward their associated polymers and thus result in the loss of efficacy. Zwitterionic poly(carboxybetaine) (PCB) is recently shown to improve the immunologic properties of proteins without inducing any antipolymer Abs against itself. However, it is unclear if the improved immunologic profiles can translate to better clinical outcomes since improved immunogenicity cannot directly reflect amelioration in efficacy. Here, a PCB nanocage (PCB NC) is developed, which can physically encase proteins while keeping their structure intact. PCB NC encapsulation of uricase, a highly immunogenic enzyme, is demonstrated to eradicate all the immune responses. To bridge the gap between immunogenicity and efficacy studies, the therapeutic performance of PCB NC uricase is evaluated and compared with its PEGylated counterpart in a clinical‐mimicking gouty rat model to determine any loss of efficacy evoked after five administrations.
A Novel Soft Actuator for the Musculoskeletal System
Authors: Wu Lianjun , Chauhan Indrajeet , Tadesse Yonas
Published: February 2018

The musculoskeletal system (MS) is essential for the movements of biological systems. Inspired by this natural structure, several attempts are made to create a synthetic MS. However, one of the challenges in developing an artificial MS for biomimetic robots is the lack of a high‐performance, low‐cost, light‐weight, and compact artificial muscle. In this Communication, a novel twisted and coiled artificial muscle is demonstrated, which is a promising actuator for the development of the artificial MS. The new muscle is made by twisting a nylon 6 fishing line precursor fiber and wrapping with a very thin (80 µm diameter) resistance wire. The resistance wire is not twisted during twist insertion of the polymer, which is very important for the performance of the muscle. The new muscle termed is integrated in a 3D printed ball‐and‐socket‐based artificial MS. Characterization results show a remarkable tensile actuation (53% strain provided at 1.69 MPa for an input current of 0.22 A). Furthermore, a bioinspired design and fabrication of the synthetic MS is illustrated incorporating antagonistic pairs capable of reaching a bending angle of 20° within 1 s. These actuators can potentially be used in other soft robots, prosthetics, and orthotics advancing the progress in the area.
Stretchable and Tailorable Triboelectric Nanogenerator Constructed by Nanofibrous Membrane for Energy Harvesting and Self‐Powered Biomechanical Monitoring
Authors: Yin Yingying , Wang Jiaona , Zhao Shuyu , Fan Wei , Zhang Xiuling , Zhang Chi , Xing Yi , Li Congju
Published: February 2018

Wearable triboelectric nanogenerators (TENGs) with both functionality and comfort have become an appealing field of research for portable electronic devices recently. Here, a breathable, stretchable, and tailorable TENG that enables both energy harvesting and biomechanical monitoring is designed. Two layers of nanofiber membranes, which consist of polyvinylidene fluoride supported by conducting fabric and thermoplastic polyurethanes (TPU) supported by Ag elastic fabric, are welded into arch structures through ultrasonic welding technique. As the bottom layer of the arch, the TPU/Ag layer with consistent stretchability guarantees the stretchable of the TENG. Therefore, the TENG can collect various types of irregular movements, such as stretching, pressing, and twisting motions, even the combination of the above all motions. Under twisting stretch, the open‐circuit voltage and short‐circuit current of one basic unit can reach up to 170 V and 4.5 µA, respectively. Besides, the welded TENG is tailorable and it still maintains certain output even if it is partially cut or damaged. The continuous arch‐structured TENGs can also be used as self‐powered motion sensors to constantly monitor the intensity and frequency of human body movements. Thus, this work opens up a new idea for preparation of wearable TENG with both multifunction and better comfort.
Visualizing the Energy Flow of Tailored Light
Authors: Zannotti Alessandro , Vasiljević Jadranka M. , Timotijević Dejan V. , Jović Savić Dragana M. , Denz Cornelia
Published: February 2018

Exploiting the energy flow of light fields is an essential key to tailor complex optical multistate spin and orbital angular momentum (OAM) dynamics. With this work, the energy flow is identified and quantified by a novel approach that is based on the symmetry breaking induced by nonlinear light–matter interaction of OAM carrying beams at the example of Mathieu beams, showing transverse invariant intensity distributions. These complex scalar nondiffracting beams exhibit outstanding transverse energy flows on elliptic paths. Although their energy is continuously redistributed during linear propagation in homogeneous media, the beams stay nondiffracting. This approach to visualize the energy flow of light is based on the nonlinear self‐action in a nonlinear crystal. By this, the sensitive equilibrium is perturbed and accumulation of rotating high‐intensity spots is enabled. Intensity distributions on elliptic, chiral paths are demonstrated as a manifestation of the energy flow. Furthermore, the formation of corresponding refractive index modulations that may be implemented as chiral waveguides, is controlled via the beam power and structure size.
High‐Throughput Fabrication of Flexible and Transparent All‐Carbon Nanotube Electronics
Authors: Chen Yong‐Yang , Sun Yun , Zhu Qian‐Bing , Wang Bing‐Wei , Yan Xin , Qiu Song , Li Qing‐Wen , Hou Peng‐Xiang , Liu Chang , Sun Dong‐Ming , Cheng Hui‐Ming
Published: February 2018

This study reports a simple and effective technique for the high‐throughput fabrication of flexible all‐carbon nanotube (CNT) electronics using a photosensitive dry film instead of traditional liquid photoresists. A 10 in. sized photosensitive dry film is laminated onto a flexible substrate by a roll‐to‐roll technology, and a 5 µm pattern resolution of the resulting CNT films is achieved for the construction of flexible and transparent all‐CNT thin‐film transistors (TFTs) and integrated circuits. The fabricated TFTs exhibit a desirable electrical performance including an on–off current ratio of more than 105, a carrier mobility of 33 cm2 V−1 s−1, and a small hysteresis. The standard deviations of on‐current and mobility are, respectively, 5% and 2% of the average value, demonstrating the excellent reproducibility and uniformity of the devices, which allows constructing a large noise margin inverter circuit with a voltage gain of 30. This study indicates that a photosensitive dry film is very promising for the low‐cost, fast, reliable, and scalable fabrication of flexible and transparent CNT‐based integrated circuits, and opens up opportunities for future high‐throughput CNT‐based printed electronics.
Effects of Voltage Biasing on Current Extraction in Perovskite Solar Cells
Authors: Hentz Olivia , Rekemeyer Paul , Gradečak Silvija
Published: February 2018

The recent rapid increase in efficiency of organic–inorganic perovskite solar cells (PSCs) has resulted in a need to develop a clear understanding of their stability and working mechanisms. In particular, it has been suggested that ion migration contributes to the commonly observed hysteresis in the current–voltage measurements of PSCs, but the rate of ion migration and its effects on the electronic properties of PSCs remain to be addressed. In this work, electron‐beam‐induced current (EBIC) is used to directly map changes in local current extraction in organic–inorganic PSCs under applied voltage. By combining EBIC mapping, standard current–voltage measurements, and external quantum efficiency measurements, it is shown that between the two potential roles that point defects play in device enhancement under voltage biasing, the effects caused by defect‐mediated ion migration outweigh the effects from the filling of trap states caused by these defects. Evidence is also provided for ion migration preferentially at local features such as extended defects. The measured timescale of tens of seconds for migration across a full device imply that ion migration contributes indirectly to the electronic capacitance of perovskite devices through interface charging.