bluuebunny/crossref_metadata_2025_split huggingface dataset:
Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals
Authors: Grauel Bettina , Würth Christian , Homann Christian , Krukewitt Lisa , Andresen Elina , Roik Janina , Recknagel Sebastian , Haase Markus , Resch-Genger Ute 
Published: August 2021

AbstractDespite considerable advances in synthesizing high-quality core/shell upconversion (UC) nanocrystals (NC; UCNC) and UCNC photophysics, the application of near-infrared (NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence (UCL) of UCNC of small size or thin protecting shell. To obtain deeper insights into energy transfer and surface quenching processes involving Yb3+ and Er3+ ions, we examined energy loss processes in differently sized solid core NaYF4 nanocrystals doped with either Yb3+ (YbNC; 20% Yb3+) or Er3+ (ErNC; 2% Er3+) and co-doped with Yb3+ and Er3+ (YbErNC; 20% Yb3+ and 2% Er3+) without a surface protection shell and coated with a thin and a thick NaYF4 shell in comparison to single and co-doped bulk materials. Luminescence studies at 375 nm excitation demonstrate back-energy transfer (BET) from the 4G11/2 state of Er3+ to the 2F5/2 state of Yb3+, through which the red Er3+4F9/2 state is efficiently populated. Excitation power density (P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and three-photonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+ emission. The intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC core. We provide a three-dimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC.
Formal design and verification of system task in intelligent transportation systems based on micro-kernel architecture
Authors: Qian Zhenjiang , Jin Yong , Sun Gaofei , Xing Xiaoshuang , Xia Kaijian 
Published: August 2021

AbstractThe accuracy of design and implementation of an operating system in intelligent transportation systems is difficult to describe and validate because of its complexity. In this paper, we describe an OS in intelligent transportation systems with automaton theory and establish an OS state model. Based on this model, we construct an isomorphic model in Isabelle/HOL, describe the work objects and operational semantics of the system, and verify the system at the assembly level. We use a micro-kernel OS prototype (VSOS) for intelligent transportation systems as an example to illustrate our method and verify the correctness of design and implementation in VSOS with Isabelle/HOL. Verification shows that the proposed method is feasible.
Verification of a chamberless HLFC design with an outer skin of variable porosity
Authors: Kilian T. , Horn M. 
Published: August 2021

AbstractA chamberless HLFC leading edge segment featuring an outer skin with variable porosity has been designed, manufactured and wind tunnel tested under flight Reynolds-number conditions. The aerodynamic design involved the extention of current HLFC design routines to variable pressure loss characteristics of the outer skin. Advanced options for structural design and manufacturing solutions with focus on industrialization, arising from the avoidance of aerodynamically driven chambering, are explored. The leading edge segment has been installed on an existing vertical tail-plane model and tested at the large low-speed wind-tunnel facility DNW-LLF. The design process and some results of the successful verification of the chamberless design are presented herein.
Certain results on invariant submanifolds of an almost Kenmotsu $$(\kappa ,\mu ,\nu )$$-space
Authors: Atc̣eken Mehmet 
Published: August 2021

AbstractIn the present paper, we study invariant submanifolds of almost Kenmotsu structures whose Riemannian curvature tensor has $$(\kappa ,\mu ,\nu )$$

(
κ
,
μ
,
ν
)

-nullity distribution. Since the geometry of an invariant submanifold inherits almost all properties of the ambient manifold, we research how the functions $$\kappa ,\mu $$

κ
,
μ

and $$\nu $$
ν
behave on the submanifold. In this connection, necessary and sufficient conditions are investigated for an invariant submanifold of an almost Kenmotsu $$(\kappa ,\mu ,\nu )$$

(
κ
,
μ
,
ν
)

-space to be totally geodesic under some conditions.
Vector analysis of electric-field-induced antiparallel magnetic domain evolution in ferromagnetic/ferroelectric heterostructures
Authors: Zhao Xinger , Hu Zhongqiang , Wu Jingen , Fang Ting , Li Yaojin , Cheng Yuxin , Zhao Yifan , Guan Mengmeng , Xian Dan , Wang Chenying , Mao Qi , Peng Bin , Peng Ren-Ci , Zhou Ziyao , Wang Zhiguang , Jiang Zhuang-De , Liu Ming 
Published: August 2021

AbstractElectric field (E-field) control of magnetism based on magnetoelectric coupling is one of the promising approaches for manipulating the magnetization with low power consumption. The evolution of magnetic domains under in-situ E-fields is significant for the practical applications in integrated micro/nano devices. Here, we report the vector analysis of the E-field-driven antiparallel magnetic domain evolution in FeCoSiB/PMN-PT(011) multiferroic heterostructures via in-situ quantitative magneto-optical Kerr microscope. It is demonstrated that the magnetic domains can be switched to both the 0° and 180° easy directions at the same time by E-fields, resulting in antiparallel magnetization distribution in ferromagnetic/ferroelectric heterostructures. This antiparallel magnetic domain evolution is attributed to energy minimization with the uniaxial strains by E-fields which can induce the rotation of domains no more than 90°. Moreover, domains can be driven along only one or both easy axis directions by reasonably selecting the initial magnetic domain distribution. The vector analysis of magnetic domain evolution can provide visual insights into the strain-mediated magnetoelectric effect, and promote the fundamental understanding of electrical regulation of magnetism.
Dyads, triads, and tetrads: a multivariate simulation approach to uncovering network motifs in social graphs
Authors: Felmlee Diane , McMillan Cassie , Whitaker Roger 
Published: August 2021

AbstractMotifs represent local subgraphs that are overrepresented in networks. Several disciplines document multiple instances in which motifs appear in graphs and provide insight into the structure and processes of these networks. In the current paper, we focus on social networks and examine the prevalence of dyad, triad, and symmetric tetrad motifs among 24 networks that represent six types of social interactions: friendship, legislative co-sponsorship, Twitter messages, advice seeking, email communication, and terrorist collusion. Given that the correct control distribution for detecting motifs is a matter of continuous debate, we propose a novel approach that compares the local patterns of observed networks to random graphs simulated from exponential random graph models. Our proposed technique can produce conditional distributions that control for multiple, lower-level structural patterns simultaneously. We find evidence for five motifs using our approach, including the reciprocated dyad, three triads, and one symmetric tetrad. Results highlight the importance of mutuality, hierarchy, and clustering across multiple social interactions, and provide evidence of “structural signatures” within different genres of graph. Similarities also emerge between our findings and those in other disciplines, such as the preponderance of transitive triads.
Utility of TPP-manufactured biophysical restrictions to probe multiscale cellular dynamics
Authors: Fei Panyu , Ding Haibo , Duan Yu , Wang Xinyi , Hu Wei , Wu Peng , Wei Mengxiao , Peng Zhengchun , Gu Zhongze , Chen Wei 
Published: August 2021

AbstractBiophysical restrictions regulate protein diffusion, nucleus deformation, and cell migration, which are all universal and important processes for cells to perform their biological functions. However, current technologies addressing these multiscale questions are extremely limited. Herein, through two-photon polymerization (TPP), we present the precise, low-cost, and multiscale microstructures (micro-fences) as a versatile investigating platform. With nanometer-scale printing resolution and multiscale scanning capacity, TPP is capable of generating micro-fences with sizes of 0.5–1000 μm. These micro-fences are utilized as biophysical restrictions to determine the fluidity of supported lipid bilayers (SLB), to investigate the restricted diffusion of Src family kinase protein Lck on SLB, and also to reveal the mechanical bending of cell nucleus and T cell climbing ability. Taken together, the proposed versatile and low-cost micro-fences have great potential in probing the restricted dynamics of molecules, organelles, and cells to understand the basics of physical biology.
Graphic abstract
Are acetic acid derivatives really negative to the iodoform test?
Authors: Nagata Daiki , Nishiwaki Nagatoshi 
Published: August 2021

AbstractAcetic acid derivatives such as ethyl acetate have been considered to be negative to the iodoform test because of the predominant hydrolysis leading to acetic acid. We clarified the immiscible property of the ester was the actual reason for the negative result. When THF or 1-propanol was used as a solvent, even alkyl acetate underwent the iodoform reaction; however, it cannot be used as qualitative test because of high solubility of iodoform into these solvents. This problem was overcome by conducting the test in methanol. Indeed, not only alkyl acetates but also N,N-dimethylacetamide showed positive to the iodoform test producing a yellow precipitates.
Performance decline in a low‐stakes test at age 15 and educational attainment at age 25: Cross‐country longitudinal evidence
Authors: Borgonovi F. , Ferrara A. , Piacentini M. 
Published: August 2021

AbstractIntroductionEducational attainment is associated with important life outcomes including labour market performance, health status, well‐being, civic and political participation. An important question is whether it is possible to identify early those students who lack the achievement motivation that is needed to complete a higher education degree.MethodsLongitudinal follow‐ups of representative samples of participants in the 2000 and 2003 Programme for International Student Assessment (PISA) from Australia, Denmark and Switzerland (N = 3110; 1130; and 1962; age = 15 to 27; % females 51%, 51%, 49%; ethnicity/race unknown) were used to identify the association between a measure of effort on a cognitively demanding low‐stake task at age 15 – performance decline during the test – and educational attainment at age 25–27.ResultsA one SD difference in performance decline was associated with a 5–6 percentage point difference in the probability of obtaining tertiary‐level qualifications (r = −0.15 in Australia; −0.11 in Denmark and −0.11 in Switzerland). We find no evidence of differences in this relationship across genders, socio‐economic status and baseline levels of ability in the three countries. The association between performance decline and educational attainment is homogeneous across these groups. Self‐reported measures of achievement motivation were not predictive of educational attainment in the three countries.ConclusionsOur work contributes new longitudinal evidence to the body of research in education employing behavioural measures of motivation and engagement. It can be used to understand the potential long‐term consequences of disparities in students' preparation to sustain effort over cognitively demanding tasks.
Application of XRF Scanning to Different Geological Archives
Authors: Guo Fei , Clemens Steven , Liu Xingxing , Long Yili , Li Dong , Tan Liangcheng , Liu Chengcheng , Yan Hong , Sun Youbin 
Published: August 2021

AbstractHigh‐resolution XRF scanning is widely used on marine and lake sediment cores as a means of rapidly acquiring elemental concentrations from closely spaced intervals with no damage to the samples. Therefore, guidance on how to obtain reliable datasets and select suitable step sizes for different geological media are of great importance. Here we apply this efficient analytical method to loess, stalagmite, and tridacna samples. The results show that 11 elements (Al, Si, K, Ca, Ti, Mn, Fe, Rb, Sr, Zr, and Ba), eight elements (Ca, Si, K, Fe, Cu, Ni, Sc, and Sr) and seven elements (Ca, Sr, Cu, Fe, Sc, Ni, and Si) can be robustly detected by this method for loess, stalagmite and tridacna archives respectively, demonstrating the capacity to reconstruct high‐resolution paleoclimate changes. For loess cores, efficiency emission decay of the X‐ray tube, water content, matrix, and grain size effects are the main factors influencing elemental intensities. The efficiency emission decay of the X‐ray tube, scanning path, scanning interval, and radiation area have a significant effect on element intensities of stalagmite and tridacna samples. Based on our investigations, we suggest optimal resolutions for scanning these three archives for millennial to seasonal‐scale paleoclimatic reconstructions. We compare our analyses with existing results from traditional (discrete) analyses, demonstrating similar scales of variability. Our results suggest that geochemical proxies measured by XRF scanning, such as Rb/Sr, Zr/Rb, and Ca/Ti ratios of loess and the Sr/Ca ratio of speleothem and tridacna, can be effectively used to reconstruct high‐resolution paleoclimate changes.
Cellulose Oxygen Isotopes of Sphagnum and Vascular Plants in a Peat Core Reveal Climate Change in Northern Japan Over the Past 2,000 Years
Authors: Sakurai Hiromichi , Yamamoto Masanobu , Seki Osamu , Omori Takayuki , Sato Tomonori 
Published: August 2021

AbstractThe cellulose δ18O of plant tissues in peat is a potential climate proxy. However, understanding what is driving the shifts in δ18O of cellulose is required for its application. Here, we analyzed the δ18O values of Sphagnum and vascular plant cellulose, as well as the δ18O and δD values of pore water, in a 4‐m‐long peat core from the Bekanbeushi ombrotrophic bog to understand paleoclimatic changes in northern Japan over the past 2,000 years. The cellulose δ18O values of Sphagnum were lower than those of vascular plant tissues, although both draw water from the same layer. Whereas the cellulose δ18O values of Sphagnum more directly reflect those of precipitation, those of vascular plants become enriched through transpiration. Thus, the difference between vascular plants and Sphagnum (Δδ18Ovp–sp) is a potential proxy for relative humidity. Cellulose δ18O of Sphagnum revealed centennial variations with maxima around 800, 1300, and 1500 CE and minima around 500, 1000, 1700, and 1900 CE. The Δδ18Ovp–sp was inversely correlated with Sphagnum cellulose δ18O, indicating that the axis of summer westerlies was more frequently located to the north and the climate was moist in the former periods, whereas the axis of summer westerlies was generally located to the south and the climate was dry in the latter periods. These results suggest a warm and moist climate during the former periods due to frequent rainy summers driven by strong East Asian summer monsoon activity, and the opposite conditions in the latter periods.
Toward a Physics Based Model of Hypervelocity Dust Impacts
Authors: Kellogg Paul J. , Bale S. D. , Goetz Keith , Monson Steven J. 
Published: August 2021

AbstractThere has been important understanding of the process by which a hypersonic dust impact makes an electrical signal on a spacecraft sensor, leading to a fuller understanding of the physics. Zaslavsky (2015), https://doi.org/10.1002/2014ja020635 showed that the most important signal comes from the charging of the spacecraft, less from charging of an antenna. The present work is an extension of the work of Zaslavsky. An analytical treatment of the physics of a hypersonic dust impact and the mechanism for generating an electrical signal in a sensor, an antenna, is presented. The treatment is compared with observations from STEREO and Parker Solar Probe. A full treatment of this process by simulations seems beyond present computer capabilities, but some parts of the treatment must depend on simulations but other features can be better understood through analytical treatment. Evidence for a somewhat larger contribution from the antenna part of the signal than in previous publications is presented. Importance of electrostatic forces in forming the exiting plasma cloud is emphasized. Electrostatic forces lead to a rapid expansion of the escaping cloud, so that it expands more rapidly than it escapes, and sometimes surrounds one or more antennas. This accounts for the ability of dipole antennas to detect dust impacts. Some progress toward understanding occasional negative charging of an antenna is presented, together with direct evidence of such charging. Use of laboratory measurements of charge to estimate size of spacecraft impacts are shown to be not reliable without further calibration work.
Impact of Stratospheric Intrusions on Ozone Enhancement in the Lower Troposphere and Implication to Air Quality in Hong Kong and Other South China Regions
Authors: Zhao Kaihui , Huang Jianping , Wu Yonghua , Yuan Zibing , Wang Yongwei , Li Ying , Ma Xiaodan , Liu Xuehui , Ma Wei , Wang Ying , Zhang Xiaoyan 
Published: August 2021

AbstractStratospheric intrusions are an important source of ozone (O3) in the troposphere. In this study, 17 years of O3 sounding data from the Hong Kong Observatory with a weekly sampling frequency are analyzed to identify stratospheric intrusions and quantify their impact on O3 enhancement events in springtime from 2004 to 2020. 24.7% of O3 enhancement events are related to stratospheric intrusion whereas 31.7% of intrusions lead to the enhancement of O3 in the lower troposphere. Occurrences of stratospheric intrusion in springtime are closely related to tropopause folding and tropospheric convective activities in subtropical regions. The Weather Research and Forecasting model coupled with Chemistry simulations are conducted with the integrated process analysis to quantify the impact of stratospheric intrusions on the enhancement of O3 in the lower free troposphere as well as near the surface under different synoptic patterns. Synoptic patterns associated with stratospheric intrusion‐driving O3 enhancements are classified into two categories: Saddle Point (“S”) and Cold Front (“F”). While downward transport of O3‐enriched air from the enhancement layer exerts an important impact on surface O3 for synoptic pattern “S,” the impact on surface O3 is limited for surface pattern “F.” The impact of stratospheric intrusions together with entrainment on surface O3 may have a strong indication on the development of effective emission control strategies on surface O3 reduction in Hong Kong.
Vertical Biogeography and Realized Niche Traits of Living Coccolithophore Community in the Eastern Indian Ocean
Authors: Liu Haijiao , Wang Dongxiao , Yun Misun , Zhang Xiaodong , Zhang Guicheng , Thangaraj Satheeswaran , Sun Jun 
Published: August 2021

AbstractCoccolithophores are crucial components of marine calcifying microalgae and found to be important indicators of ecological changes. The interannual scale and vertical biogeography of springtime living coccolithophore communities were determined in the chronically under‐sampled eastern Indian Ocean (EIO) during seven consecutive years (spring 2011–2018). In addition, we quantified the realized ecological niches of dominant coccolithophore species in the region based on the ecological modeling method (MaxEnt statistics). Results indicated the interannual mean coccolithophore abundance ranged 4,306–11,140 cells L−1. The ecologically important species such as Gephyrocapsa oceanica, Emiliania huxleyi, Algirosphaera robusta, Florisphaera profunda, Umbilicosphaera sibogae, and Umbellosphaera irregularis were identified as dominant species in the coccolithophore community. Based on the ratios of coccoliths and plated coccolithophores, we observed coccolith detachment rates showed a valley near deep chlorophyll maximum layer and peaked in the surface or bottom of euphotic layer which was potentially relevant to near‐surface circulations, nutrients and light availability. From applying the ecological modeling method, we quantified three types of realized niches in coccolithophore species based on mean niche (μ) and breadth of niche (σ) which were consistent with their conventionally vertical biogeography. Our data set could be further incorporated into climatic ecological models.
Calcareous Nannofossil Size and Abundance Response to the Messinian Salinity Crisis Onset and Paleoenvironmental Dynamics
Authors: Mancini A. M. , Grelaud M. , Ziveri P. , Nallino E. , Lozar F. 
Published: August 2021

AbstractDwarfism is a common feature affecting organisms across extreme events that characterized the Earth history, frequently referred as the result of “stressed conditions.” To date, no study addressed the morphological and biometric changes across the Messinian Salinity Crisis (MSC), one of the most recent and impacting event occurred in the Mediterranean Sea, historically interpreted as characterized by hypersaline conditions. Here we focus on morpho/biometric changes affecting calcareous nannofossils (CN) toward the MSC onset in order to better constrain the paleoenvironmental dynamics and the loosely defined “stressed conditions” characterizing this interval. Size characterization and absolute abundance of selected CN taxa were performed in the Perales (Spain, Western Mediterranean) and in the Banengo and Pollenzo sections (Italy, Northern Mediterranean). We also tested whether size changes and orbital cyclicity were related through analyzing size and calcite mass of Reticulofenestra minuta using an automated image analysis system of CN recognition (SYRACO). We recorded a significant size reduction affecting the CN taxa involved in the MSC onset bioevent, related to the restriction of the Mediterranean Basin that resulted in increased productivity and enhanced environmental variability, stimulating CN growth rate and decreasing their platelet sizes. Reticulofenestra minuta size and mass correlate with the orbital cyclicity with minimum values during periods of enhanced environmental variability, coinciding with the diatomite deposition in the Sorbas Basin. Our finding reveals that the size change recorded across the MSC onset coincided with the instauration of a productive and highly variable environment, linked to the restriction of the paleo Gibraltar Strait.
Limiting Behavior of the Probability Distribution in Einstein's Bed‐Load Formula and its Improvement
Authors: Wu Haoliang , Cheng Nian‐Sheng , Chiew Yee‐Meng 
Published: August 2021

AbstractThe bed‐load transport rates predicted using Einstein's formula in the low and high transport regimes deviate from the experimental data. The deviation, which becomes significant when the transport rate is extremely low or high, may be solely attributed to the folded Gaussian distribution assumed by Einstein. The trends of an Einstein‐type formula at the limits can be separately determined by considering the limiting behavior of the embedded probability distribution, which facilitates the derivation of a formula that best fits the bed‐load data. By applying a Gamma distribution with the shape parameter equal to 3/2, a modified Einstein's formula is successfully applied to the low and high transport regimes.