bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasmall Optical Vortex Knots Generated by Spin‐Selective Metasurface Holograms
Authors: Wang Lei , Zhang Weixuan , Yin Hongxing , Zhang Xiangdong 
Published: March 2019

AbstractTying isolated vortex knots in complex optical fields has been recently realized using spatial light modulators (SLMs). These traditional devices suffer from low efficiency, narrow bandwidth, and they cannot be integrated to nanophotonic systems. Here, the design and realization of metasurface holograms (MHs) is reported to efficiently generate the optical vortex knots in a broad spectral region. In comparison with conventional optical devices, the thicknesses and pixels of MHs are both in subwavelength scale, and the size of created optical vortex knot can be six orders of magnitude smaller than those produced by SLMs. Such extremely little vortex knots may find widespread applications in templating knotted micro/nano‐structures in photosensitive materials and 3D optical trapping of cold atoms in complex topologies at microscale. In particular, it is found that the spatial position of the generated off‐axis optical vortex knot is able to be symmetrically reversed by just changing the helicity of the incident light. This spin‐selective vortex knot generator can be regarded as a new type of metasurface device for manipulating the topological structure of optical vortex lines, which has potential applications in the field of singular optics.
The City and Extreme Weather: How Cities Should Respond to Climate Change
Authors: Kaltenbrunner Robert 
Published: March 2019

AbstractThe following essay focuses on the impacts of climate toward cities—and on the inherent restraints, which one has to deal with. There is today a necessity of strategies for urban resilience. These move away from the idea that space must be used in the most efficient way possible: instead, tolerances will be built in, buffers formed, which should lead at the same time to added spatially quantitative value. It is as right as it is necessary to develop a vision of climate‐friendly and CO2‐neutral cities and regions. On the one hand, one must ask how all of the uncertainties can be handled in the planning. On the other hand, one must engage oneself to anchor—more precisely, to better anchor—integrated climate protection and adaptation strategies to everyday activities: not only for regional planning or urban development, but also among private builders and property owners.
2D Single‐Layer π‐Conjugated Nickel Bis(dithiolene) Complex: A Good‐Electron‐Poor‐Phonon Thermoelectric Material
Authors: Deng Tianqi , Yong Xue , Shi Wen , Gan Chee Kwan , Li Wu , Hippalgaonkar Kedar , Zheng Jin‐Cheng , Wang Xiaobai , Yang Shuo‐Wang , Wang Jian‐Sheng , Wu Gang 
Published: March 2019

AbstractRecently, the 2D d8 planar π‐conjugated transition metal complexes have gained extensive attention owing to their extra‐high electrical conductivity. Meanwhile, low lattice thermal conductivities can be expected for their soft and microporous structures, suggesting very promising thermoelectric applications. Herein, based on first‐principles calculations and molecular dynamics simulations, it is identified that monolayered 2D nickel bis(dithiolene) complex, (NiC4S4)n, is indeed such a material that exhibits exceptionally high electron mobility, low lattice thermal conductivity, and thereby excellent thermoelectric performance. The calculated figure of merit at 300 K can reach up to 0.92 for a perfect nanosheet. At the same time, the mechanism behind is uncovered, that is, the weak electron‐acoustic‐phonon coupling allowing high electron mobility, and its microporous structure decreasing the thermal transport. The surprisingly weak electron‐acoustic‐phonon coupling arises from mixed bonding–antibonding nature of conduction band. The finding opens a new opportunity for these 2D coordination complexes as potential thermoelectric materials.
High‐Performance Electrocatalytic Conversion of N2 to NH3 Using Oxygen‐Vacancy‐Rich TiO2 In Situ Grown on Ti3C2Tx MXene
Authors: Fang Yanfeng , Liu Zaichun , Han Jingrui , Jin Zhaoyong , Han Yaqian , Wang Faxing , Niu Yusheng , Wu Yuping , Xu Yuanhong 
Published: March 2019

AbstractTo achieve the energy‐effective ammonia (NH3) production via the ambient‐condition electrochemical N2 reduction reaction (NRR), it is vital to ingeniously design an efficient electrocatalyst assembling the features of abundant surface deficiency, good dispersibility, high conductivity, and large surface specific area (SSA) via a simple way. Inspired by the fact that the MXene contains thermodynamically metastable marginal transition metal atoms, the oxygen‐vacancy‐rich TiO2 nanoparticles (NPs) in situ grown on the Ti3C2Tx nanosheets (TiO2/Ti3C2Tx) are prepared via a one‐step ethanol‐thermal treatment of the Ti3C2Tx MXene. The oxygen vacancies act as the main active sites for the NH3 synthesis. The highly conductive interior untreated Ti3C2Tx nanosheets could not only facilitate the electron transport but also avoid the self‐aggregation of the TiO2 NPs. Meanwhile, the TiO2 NPs generation could enhance the SSA of the Ti3C2Tx in return. Accordingly, the as‐prepared electrocatalyst exhibits an NH3 yield of 32.17 µg h−1 mg−1cat. at −0.55 V versus reversible hydrogen electrode (RHE) and a remarkable Faradaic efficiency of 16.07% at −0.45 V versus RHE in 0.1 m HCl, placing it as one of the most promising NRR electrocatalysts. Moreover, the density functional theory calculations confirm the lowest NRR energy barrier (0.40 eV) of TiO2 (101)/Ti3C2Tx compared with Ti3C2Tx or TiO2 (101) alone.
Evaluating elbow osteoarthritis within the prehistoric Tiwanaku state using generalized estimating equations (GEE)
Authors: Becker Sara K. 
Published: March 2019

AbstractObjectivesStudies of osteoarthritis (OA) in human skeletal remains can come with scalar problems. If OA measurement is noted as present or absent in one joint, like the elbow, results may not identify specific articular pathology data and the sample size may be insufficient to address research questions. If calculated on a per data point basis (i.e., each articular surface within a joint), results may prove too data heavy to comprehensively understand arthritic changes, or one individual with multiple positive scores may skew results and violate the data independence required for statistical tests. The objective of this article is to show that the statistical methodology Generalized Estimating Equations (GEE) can solve scalar issues in bioarchaeological studies.Materials and methodsUsing GEE, a population‐averaged statistical model, 1,195 adults from the core and one colony of the prehistoric Tiwanaku state (AD 500–1,100) were evaluated bilaterally for OA on the seven articular surfaces of the elbow joint.ResultsGEE linked the articular surfaces within each individual specimen, permitting the largest possible unbiased dataset, and showed significant differences between core and colony Tiwanaku peoples in the overall elbow joint, while also pinpointing specific articular surfaces with OA. Data groupings by sex and age at death also demonstrated significant variation. A pattern of elbow rotation noted for core Tiwanaku people may indicate a specific pattern of movement.DiscussionGEE is effective and should be encouraged in bioarchaeological studies as a way to address scalar issues and to retain all pathology information.
Carotid foramen size in the human skull tracks developmental changes in cerebral blood flow and brain metabolism
Authors: Harrington Arianna R. , Kuzawa Christopher W. , Boyer Doug M. 
Published: March 2019

AbstractObjectivesIn humans, neuronal processes related to brain development elevate the metabolic rate of brain tissue relative to the body during early childhood. This phenomenon has been hypothesized to contribute to slow somatic growth in preadolescent Homo sapiens. The uncoupling of the brain's metabolic rate from brain size during development complicates the study of the evolutionary emergence of these traits in the fossil record. Here, we extend a method previously developed to predict interspecific differences in cerebral blood flow (a correlate of cerebral glucose use) to predict ontogenetic changes in human brain metabolism.Materials and methodsRadii of the carotid foramen from an ontogenetic series of modern human crania were used to predict blood flow rates through the internal carotid arteries (ICA), which were compared to empirically measured ICA flow and brain metabolism values.ResultsPredictions of both absolute ICA blood flow rates and perfusion (ICA blood flow rates relative to brain size) generally match measured values in infancy and childhood. Maximum predicted ICA blood flow rates and perfusion were found to occur between ages 5 and 8, which roughly correspond to the age of maximum measured ICA blood flow rate and absolute and brain mass‐specific rate of whole brain glucose uptake.DiscussionThese findings suggest that, during human growth and development, the size of the carotid foramen corresponds well to blood flow requirements through the ICA, and the method tested here may provide new opportunities for studying developmental changes in brain metabolism using osteological samples, including fossil hominins.
Self‐Assembly through Coordination and π‐Stacking: Controlled Switching of Circularly Polarized Luminescence
Authors: Niu Dian , Jiang Yuqian , Ji Lukang , Ouyang Guanghui , Liu Minghua 
Published: March 2019

AbstractMultiple noncovalent interactions can drive self‐assembly through different pathways. Here, by coordination‐assisted changes in π‐stacking modes between chromophores in pyrene‐conjugated histidine (PyHis), a self‐assembly system with reversible and inversed switching of supramolecular chirality, as well as circularly polarized luminescence (CPL) is described. It was found that l‐PyHis self‐assembled into nanofibers showing P‐chirality and right‐handed CPL. Upon ZnII coordination, the nanofibers changed into nanospheres with M‐chirality, as well as left‐handed CPL. The process is reversible and the M‐chirality can change to P‐chirality by removing the ZnII ions. Experimental and theoretical models unequivocally revealed that the cooperation of metal coordination and π‐stacking modes are responsible the reversible switching of supramolecular chirality. This work not only provides insight into how multiple noncovalent interactions regulate self‐assembly pathways.
Synthesis of Urea Derivatives from CO2 and Silylamines
Authors: Xu Maotong , Jupp Andrew R. , Ong Maegan S. E. , Burton Katherine I. , Chitnis Saurabh S. , Stephan Douglas W. 
Published: March 2019

AbstractA series of thirty‐three N,N′‐diaryl, dialkyl, and alkyl‐aryl ureas have been prepared in pyridine or toluene by reaction of silylamines with CO2. This protocol is shown to provide facile access to 13C‐labeled ureas, as well as chiral and macrocyclic ureas. These reactions proceed through initial generation of the corresponding silylcarbamates, which subsequently react with silylamine under thermal conditions to afford the thermodynamically favored urea and disilyl ether.
Chemical Vapor Deposition of Phase‐Pure Uranium Dioxide Thin Films from Uranium(IV) Amidate Precursors
Authors: Straub Mark D. , Leduc Jennifer , Frank Michael , Raauf Aida , Lohrey Trevor D. , Minasian Stefan G. , Mathur Sanjay , Arnold John 
Published: March 2019

AbstractHomoleptic uranium(IV) amidate complexes have been synthesized and applied as single‐source molecular precursors for the chemical vapor deposition of UO2 thin films. These precursors decompose by alkene elimination to give highly crystalline phase‐pure UO2 films with an unusual branched heterostructure.
Fire retardance and smoke suppression of polypropylene with a macromolecular intumescent flame retardant containing caged bicyclic phosphate and piperazine
Authors: Yang Rong , Ma Binbin , Zhang Xin , Li Jinchun 
Published: March 2019

ABSTRACTA macromolecular intumescent flame retardant (FR) named PPPAP was designed and synthesized with phosphorus chloride (the acid source), 2,6,7‐trioxa‐l‐phosphabicyclo[2.2.2]‐octane‐4‐methanol (the charring agent), and anhydrous piperazine (the blowing agent). Then, it was used to prepare an intumescent flame‐retardant polypropylene (FR‐PP). The thermal stability, flame retardancy, and fire performance of the FR‐PPs were investigated. The results show that the initial decomposition temperature and char residue at 700 °C of PPPAP were 260.8 °C and 31.8%, respectively. The limiting oxygen index (LOI) value of polypropylene (PP) was enhanced with increasing PPPAP content. With the addition of 40 wt % PPPAP, the LOI value of FR‐PP was 29%, and it passed the vertical burning UL‐94 V‐0 rating. The cone calorimetry results indicate that not only the peak heat‐release rate but also the total smoke production of PP significantly decreased to 65.7 and 79.5%, respectively, with the incorporation of only 20 wt % PPPAP. The FR mechanism suggested that PPPAP played a part in both the gas and condensed phases, and the formation of the intumescent char layer during combustion was the dominant FR mechanism. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47593.
Feasibility of unsaturated fatty acid feedstocks as green alternatives in bio‐oil refinery
Authors: Jeon Jong Yeol , Han Yohan , Kim Young‐Wun , Lee Youn‐Woo , Hong Sukwon , Hwang In Taek 
Published: March 2019

AbstractBio‐oil contains plant, animal, fish, and micro‐algae oil, and more than 200 million tons are produced annually. However, many edible and non‐edible bio‐oils are still under development, and their value and feasibility have yet to be determined. The vast majority of bio‐oils produced in the world have a very high unsaturated fatty acid content (70–98%), which could be used as a renewable, eco‐friendly alternative to petroleum. Hydrolysis (or transesterification) with ethylene metathesis technology converts unsaturated fatty acids to C4–C30 oil fragments. These oil fragments are a sustainable chemical technology used in chemical industry platform technology and carbon dioxide abatement green chemical technology, and as a petrochemical substitute. These platform chemicals also have their own market but are used as raw materials for other products (polymers, surfactants, synthetic lubricants, plasticizers, other specialty chemicals, general purpose chemicals, biofuels, etc.). The biodegradability and biocompatibility of the polymeric materials made from the oil mean that it is also possible to develop diverse functional products with high added value such as toothpaste, dandruff treatment shampoo, and melanin pigment removal cosmetics, medical and shape memory polymer materials. According to the cradle‐to‐gate analysis for environmental impact and economics, the total carbon dioxide emission reduction per ton of soybean oil was estimated to be 1.5 kg kg−1 products. Moreover, the metathesis of soybean oil ($680/ton) with additional raw materials ($237.4) will generate a value that is 7.5 times higher at $6857. Due to the biodegradability and biocompatibility of the products made from bio‐oils, it is expected that various functional products with high added value will be developed and that industrial applicability will be greatly expanded in the near future. In addition, for the development of various derivatives, fusion and cooperative research in chemical fields such as catalytic engineering, organic chemistry, polymer chemistry, maintenance chemistry, and reaction engineering are essential. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd
Neuropeptidomics: Comparison of parallel reaction monitoring and data‐independent acquisition for the analysis of neuropeptides using high‐resolution mass spectrometry
Authors: Saidi Mouna , Kamali Soufiane , Beaudry Francis 
Published: March 2019

AbstractTargeted peptide quantitation by mass spectrometry is a rapidly emerging field. Traditionally it relied on the development and validation of multiple reaction monitoring assays that could comply with a high level of sensitivity, specificity, accuracy and reproducibility in complex biological samples. However, with the introduction of high‐resolution mass spectrometers, other acquisition modes could provide more comprehensive datasets for identification and quantification but also for in‐depth data mining. The objective of this study was to evaluate two analytical approaches, parallel‐reaction monitoring (PRM) and data‐independent analysis (DIA) using a hybrid Quadrupole–Orbitrap mass spectrometer for the quantification of neuropeptides in animal spinal cord tissues. Mouse spinal cord tissues were harvested, homogenized and neuropeptides extracted using a C18 solid‐phase extraction protocol. Chromatography was achieved using a Thermo Biobasic C8 100 × 1 mm (5 μm) column. The initial mobile phase conditions consisted of acetonitrile and water (both containing 0.1% of formic acid) at a ratio of 5:95. An 11 min linear gradient was applied up to a ratio of 50:50 and maintained for 3 min. The flow rate was fixed at 75 μL/min and 2 μL of sample was injected. Mass spectrometry analyses were performed using a Thermo Q Exactive Plus MS using PRM and DIA approaches. Quantitative data using an isotopic dilution and a label‐free strategy were obtained for both methods and statistically compared. Using both approaches, we were able to clearly detect endogenous neuropeptides. However, with DIA, mass spectra alone could not distinguish Leu‐Enk and Met‐Enk. We used a Bland–Altman plot (Difference plot) to analyze the agreement between both approaches and no systematic bias was observed. Further statistical analyses, including variance analysis, showed more variability in DIA compared with PRM mode. Further analyses were performed using a label‐free approach and confirmed an increase of the variance using a DIA approach.
Muscle power, contraction velocity and functional performance after stroke
Authors: Kostka Joanna , Niwald Marta , Guligowska Agnieszka , Kostka Tomasz , Miller Elżbieta 
Published: March 2019

AbstractObjectiveThe goal of this study was to describe muscle function deficit in patients after stroke as well as to define the relationship between maximal muscle power (Pmax) and optimal shortening velocity (υopt) with functional efficiency in stroke survivors.Material and MethodsA total of 134 participants were enrolled in the study, including 67 patients after a stroke and 67 volunteers, matched for age and sex (controls). Functional performance was measured with the timed Up and Go test (TUG) and additionally with Rivermead Motor Assessment (RMA) and Barthel Index (BI) in stroke survivors. To assess Pmax and υopt of the knee extensor muscles, a specially equipped Monark cycle ergometer was used.ResultsThe power generated by stroke survivors was 49.6% that of their peers and muscle contraction velocity was 65.5%. Pmax/kg and υopt were associated with TUG outcomes in both groups. Pmax/kg and υopt were associated with age in the control group, but not in patients after stroke. In multivariate analysis in patients after stroke, TUG was better predicted by Pmax/kg or υopt than by the age. In stroke survivors, both Pmax/kg and υopt were related to the BI and to the RMA total results. Both BI and RMA total were not determined by age.ConclusionsMuscle power and muscle contraction velocity in patients who have had a stroke within three months have reduced markedly. These factors significantly affect functional performance. Muscle power and optimal shortening velocity are more important determinants of functional status than age in these stroke survivors.
Teaching combustion thermochemistry with an interactive Matlab application
Authors: García‐Oliver José María , García Antonio , de la Morena Joaquín , Monsalve‐Serrano Javier 
Published: March 2019

AbstractComputer‐aided‐learning has been found to improve notably the learning efficiency as compared with classical teaching. In this study, an interactive Matlab application has been developed to be used when teaching combustion thermochemistry in engineering degrees. The use of this tool in practical sessions allows the students to concentrate on understanding the links between the boundary conditions of a combustion process and the corresponding outputs in terms of species composition and temperature. Moreover, the students can check the differences between the results obtained from a complex calculation (with the interactive tool) and those obtained by means of the simplified calculations performed during the theoretical lessons and written exams. The analysis of the outcomes after several years using this tool revealed that the students are generally satisfied with the practical session, and the analysis of the marks confirms the robustness of the methodology proposed.
Boron−Boron Dehydrocoupling of Boranes Initiated by Reaction with Iodine
Authors: Elias Jana , Kaifer Elisabeth , Himmel Hans‐Jörg 
Published: March 2019

AbstractA new boron–boron dehydrocoupling strategy was established, providing convenient access to some diborane(4) compounds starting from simple borane adducts under mild conditions. In contrast to the traditional pathway using a reducing reagent, the reduction from BIII to BII was paradoxically initiated by the addition of the oxidation‐reagent iodine. A reaction pathway for this unusual reaction was proposed based on quantum‐chemical calculations.
Analysis of Membrane Reactors for Integrated Coupling of Oxidative and Thermal Dehydrogenation of Propane
Authors: Brune Andreas , Wolff Tanya , Seidel‐Morgenstern Andreas , Hamel Christof 
Published: March 2019

AbstractThis study presents strategies capable to intensify the thermal dehydrogenation of propane (TDH) using integrated reactor concepts. An inert packed bed membrane reactor for distributed dosing of oxygen to realize the oxidative dehydrogenation (ODH) was studied and compared to a reactor with catalytically active membrane. The latter concept allows to combine TDH and ODH in one apparatus to overcome the chemical equilibrium by in situ conversion of the by‐product H2using O2or in a reverse water‐gas shift reaction by CO2. If CO2is used as active sweep gas the reactor offered better performance regarding yield and selectivity. Strategies for further thermal integration are discussed.
Macroscopic and mesoscopic simulation of viscoelastic free surface flow in gas‐assisted injection moulding process
Authors: Li Qiang , Niu Haifeng , Yuan Jinyun 
Published: March 2019

AbstractIn this work, an improved simple coupled level‐set and volume of fluid (S‐CLSVOF) method is proposed to trace the moving interfaces in gas assisted injection moulding (GAIM) process based on the viscoelastic FENE‐P model. Firstly, the Kreisselmeier‐Steinhauser (KS) function constructed by means of Boolean operations is adopted as the shape level set (LS) function to precisely represent the complex mould cavities. Then, the benchmark problem of two‐dimensional deformation is used to verify the ability of the S‐CLSVOF method for capturing the moving interfaces. The stress birefringence is calculated and compared with the experiment result. Finally, the proposed method is further applied to the mould filling and gas penetration processes in GAIM. The macroscopic bubble appearance, temperature distribution, and the behaviour of the mesoscopic molecular orientation are shown and analyzed in detail. Due to the complexity of the gas‐liquid interaction, the phenomenon of asymmetrical gas flow is clearly observed in the gas penetration process. The influences of the macroscopic parameters on the macroscopic gas flows and mesoscopic molecular orientation are also discussed, such as insert positions, melt temperatures, and gas delay time. The numerical results illustrate that the coupled method can be applied to the multiscale numerical simulation of viscoelastic flows with complex free surfaces and provide significant guidance for the GAIM process.