bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of liquid‐side mass transfer coefficient and liquid film thickness in a bubble column using single spherical bubble model
Authors: Sujan Ajay , Vyas Raj K. , Singh Kailash 
Published: February 2018

AbstractA macroscopic mass transfer model based on the unsteady‐state liquid film mass transfer mechanism for a single spherical bubble was formulated. Analytical solution of the model equation was obtained in Laplace transform using surface renewal rates based on Danckwerts' surface age distribution function. The mass transfer coefficient, kL, in a slurry bubble column under different operating conditions of temperature, pressure, gas flow rate, and solid concentration has been simulated using a program code “BUBBLESIM” in MATLAB®, developed by the authors. The proposed model has been validated using secondary data for a slurry system under a wide range of operating conditions. The predicted values of kL show very good agreement with the experimental data within an average deviation of ±2%. The results show that the mass transfer coefficient, kL, increased with increasing superficial gas velocity and temperature and decreased with increase in slurry concentration, while it changed slightly with pressure. Based on the present work, empirical correlations have been proposed for the prediction of δ in terms of dimensionless groups for H2–, CO–, and CO2–paraffin–quartz sand systems under elevated temperatures (298–423 K) and elevated pressures (1–3 MPa) in a slurry bubble column.
Synthesis and characterization of SSS/HAM/AA terpolymer as a fluid loss additive for oil well cement
Authors: Wu Jing , Li Ming , Zhang Aili 
Published: February 2018

ABSTRACTA terpolymer comprising of sodium styrene sulfonate (SSS), n‐methylol acrylamide (HAM), and acrylic acid (AA) was synthesized by aqueous free radical copolymerization and evaluated as fluid loss additive (FLA) in oil well cement. In this article, HAM is first introduced in the preparation of FLA as an environment‐friendly monomer, which effectively improves the adhesion and fluid loss control of the terpolymer. The experimental synthesis conditions were optimized by orthogonal experiments. The molecule weight of the terpolymer was determined by gel permeation chromatography. The molecule structure of the synthesized terpolymer was verified by X‐ray photoelectron spectroscopy and Fourier transformer infrared spectrum. The thermal stability of the synthesized terpolymer was tested by thermogravimetry (TG). The structure of the terpolymer aqueous solution was observed by scanning electron microscope. The results show that SSS/HAM/AA has an excellent thermal resistant. The thermal degradation is not obvious before 295.2 °C. Furthermore, the microstructure of SSS/HAM/AA in water conducive to good fluid loss control ability. When the dosage of SSS/HAM/AA is up to 2.0% in fresh water cement slurry, the filtration loss [FL(HTHP)] can be controlled within 50 mL at 90–150 °C. SSS/HAM/AA has an excellent property of reducing filtration loss. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46266.
QM/MM Studies on Photoisomerization Dynamics of Azobenzene Chromophore Tethered to a DNA Duplex: Local Unpaired Nucleobase Plays a Crucial Role
Authors: Wu Dan , Wang Ya‐Ting , Fang Wei‐Hai , Cui Ganglong , Thiel Walter 
Published: February 2018

AbstractThe photoresponsive azobenzene‐tethered DNAs have received growing experimental attention because of their potential applications in biotechnology and nanotechnology; however, little is known about the initial photoisomerization of azobenzene in these systems. Herein we have employed quantum mechanics/molecular mechanics (QM/MM) methods to explore the photoisomerization dynamics of an azobenzene‐tethered DNA duplex. We find that in the S1 state the trans–cis photoisomerization path is much steeper in DNA than in vacuo, which makes the photoisomerization much faster in the DNA environment. This acceleration is primarily caused by complex steric interactions between azobenzene and the nearby unpaired thymine nucleobase, which also change the photoisomerization mechanism of azobenzene in the DNA duplex.
Magnetic Switching by the In Situ Electrochemical Control of Quasi‐Spin‐Peierls Singlet States in a Three‐Dimensional Spin Lattice Incorporating TTF‐TCNQ Salts
Authors: Fukunaga Hiroki , Tonouchi Masanori , Taniguchi Kouji , Kosaka Wataru , Kimura Shojiro , Miyasaka Hitoshi 
Published: February 2018

AbstractMagnetic phase switching in a coordination polymer is reported, which is demonstrated by combining two processes: (A) the pre‐organization of magnetic/redox‐active molecules into a framework, and (B) a post‐treatment through electrochemical tuning of the pre‐organized molecules. A TTF.+–TCNQ.− salt (TTF=tetrathiafulvalene; TCNQ=7,7,8,8‐tetracyano‐p‐quinodimethane) was incorporated into a three‐dimensional framework with paddlewheel‐type dimetal(II, II) units ([M2II,II]; M=Ru with S=1, 1; and Rh with S=0, 2), where the [M2II,II] and TCNQ.− units form the coordinating framework, and TTF.+is located in the pores of framework, forming an irregular π‐stacking alternating column with the TCNQ.− in the framework. In 1, the spins of [Ru2II,II] and TCNQ.− units make a magnetic correlation through the framework upon decreasing the temperature from 300 K, which is, however, suddenly suppressed below 137 K (=Td (1)) by the formation of a spin singlet in the TTF.+–TCNQ.− columns, as seen in the spin‐Peierls transition (Td (2)=200 K). This material was incorporated as a cathode in a Li‐ion battery (LIB); a long‐range ferrimagnetic correlation was formed through the three‐dimensional [{Ru2II,II}2TCNQ]− framework at Tc=78 K in the discharge process. The reversible magnetic phase switching between the non‐volatile ferrimagnetic and paramagnetic states, resulting from the local spin tuning of quasi‐spin‐Peierls singlet, is demonstrated through the discharge/charge cycling of the LIB.
Sensitive and Specific Guest Recognition through Pyridinium‐Modification in Spindle‐Like Coordination Containers
Authors: Bhuvaneswari Nagarajan , Dai Feng‐Rong , Chen Zhong‐Ning 
Published: February 2018

AbstractAn elaborately designed pyridinium‐functionalized octanuclear zinc(II) coordination container 1‐Zn was prepared through the self‐assembly of Zn2+, p‐tert‐butylsulfonylcalix[4]arene, and pyridinium‐functionalized angular flexible dicarboxylate linker (H2BrL1). The structure was determined by a single‐crystal X‐ray diffractometer. 1‐Zn displays highly sensitive and specific recognition to 2‐picolylamine as revealed by drastic blueshifts of the absorption and emission spectra, ascribed to the decrease of intramolecular charge transfer (ICT) character of the container and the occurrence of intermolecular charge transfer between the host and guest molecules. The intramolecular charge transfer plays a key role in the modulation of the electronic properties and is tunable through endo‐encapsulation of specific guest molecules.
Sulfur Hydrogen Bonding in Isolated Monohydrates: Furfuryl Mercaptan versus Furfuryl Alcohol
Authors: Juanes Marcos , Lesarri Alberto , Pinacho Ruth , Charro Elena , Rubio José E. , Enríquez Lourdes , Jaraíz Martín 
Published: February 2018

AbstractThe hydrogen bonds involving sulfur in the furfuryl mercaptan monohydrate are compared with the interactions originating from the hydroxyl group in furfuryl alcohol. The dimers with water were created in a supersonic jet expansion and characterized using microwave spectroscopy and supporting molecular orbital calculations. In furfuryl alcohol–water, a single isomer is observed, in which the water molecule forms an insertion complex with two simultaneous hydrogen bonds to the alcohol (O−H⋅⋅⋅Ow) and the ring oxygen (Ow−H⋅⋅⋅Or). When the alcohol is replaced by a thiol group in furfuryl mercaptan–water, two isomers are observed, with the thiol group preferentially behaving as proton donor to water. The first isomer is topologically equivalent to the alcohol analog but the stronger hydrogen bond is now established by water and the ring oxygen, assisted by a thiol S−H⋅⋅⋅Owhydrogen bond. In the second isomer the sulfur group accepts a proton from water, forming a Ow−H⋅⋅⋅S hydrogen bond. Binding energies for the mercaptan–water dimer are predicted around 12 kJ mol−1weaker than in the alcohol hydrate (B3LYP‐D3(BJ)). The non‐covalent interactions in the furfuryl dimers are dominantly electrostatic according to a SAPT(0) energy decomposition, but with increasing dispersion components in the mercaptan dimers, which are larger for the isomer with the weaker Ow−H⋅⋅⋅S interaction.
Dicyanamide Salts that Adopt Smectic, Columnar, or Bicontinuous Cubic Liquid‐Crystalline Mesophases
Authors: Park Geonhui , Goossens Karel , Shin Tae Joo , Bielawski Christopher W. 
Published: February 2018

AbstractAlthough dicyanamide (i.e., [N(CN)2]−) has been commonly used to obtain low‐viscosity, halogen‐free, room‐temperature ionic liquids, liquid‐crystalline salts containing such anions have remained virtually unexplored. Here we report a series of amphiphilic dicyanamide salts that, depending on their structures and compositions, adopt smectic, columnar, or bicontinuous cubic thermotropic liquid‐crystalline mesophases, even at room temperature in some cases. Their thermal properties were explored by polarized light optical microscopy, differential scanning calorimetry, thermogravimetric analysis (including evolved gas analysis), and variable‐temperature synchrotron X‐ray diffraction. Comparison of the thermal phase characteristics of these new liquid‐crystalline salts featuring “V‐shaped” [N(CN)2]− anions with those of structural analogues containing [SCN]−, [BF4]−, [PF6]−, or [CF3SO3]− anions indicated that not only the size of the counterion but also its shape should be considered in the development of mesomorphic salts. Collectively, these discoveries may be expected to facilitate the design of thermotropic ionic liquid crystals that form inverted‐type bicontinuous cubic and other sophisticated liquid‐crystalline phases.
Specific Interaction Sites Determine Differential Adsorption of Protein Structural Isomers on Nanoparticle Surfaces
Authors: Bortot Andrea , Zanzoni Serena , D'Onofrio Mariapina , Assfalg Michael 
Published: February 2018

AbstractIn biological systems, nanoparticles (NPs) elicit bioactivity upon interaction with proteins. As a result of post‐translational modification, proteins occur in a variety of alternative covalent forms, including structural isomers, which present unique molecular surfaces. We aimed at a detailed description of the recognition of protein isomeric species by NP surfaces. The transient adsorption of isomeric ubiquitin (Ub) dimers by NPs was investigated by solution NMR spectroscopy. Lys63‐ and Lys48‐linked Ub2 were adsorbed by large anionic NPs with different affinities, whereas the binding strength was similar in the cases of smaller particles. After the incorporation of paramagnetic tags into NPs, the observed site‐resolved paramagnetic footprints provided a high‐resolution map of the different protein surfaces binding to NPs. The approach described could be extended to further protein isoforms and more specialized NP systems to allow better control of the interactions between NPs and protein targets.
The Second Visual System of The Tree Shrew
Authors: Petry Heywood M. , Bickford Martha E. 
Published: February 2018

AbstractThis review provides a historical account of the discovery of secondary visual pathways (from retina to the superior colliculus to the dorsal thalamus and extrastriate cortex), and Vivien Casagrande's pioneering studies of this system using the tree shrew as a model. Subsequent studies of visual pathways in the tree shrew are also reviewed, beginning with a description of the organization and central projections of the tree shrew retina. The organization and connectivity of second visual system components that include the retino‐recipient superior colliculus, tecto‐recipient pulvinar nucleus and its projections, and the tecto‐recipient dorsal lateral geniculate nucleus and its projections are detailed. Potential functions of the second visual system are discussed in the context of this work and in the context of the behavioral studies that initially inspired the secondary visual system concept.
The Effect of Power, Pulse Rate and Treatment Time of Sonication on the Nucleation and Growth of α‐Lactose Monohydrate (α‐LM) Single Crystals from Aqueous Solution
Authors: Vinodhini Kandasamy , Srinivasan K. 
Published: February 2018

AbstractIn the present study, different kinds of ultrasound variables such as power (P‐75W to 225W), pulse rate (Pr‐10s to 60s) and treatment time (T‐04 min and T‐08 min) are employed on the crystallization of α‐ lactose monohydrate (α‐LM) from aqueous solution. The applied energy density of sonication in aqueous solution shows a profound effect on the nucleation and growth characteristics of α‐LM as regards the principal benefits such as reduction of induction period and supersaturation levels required for nucleation, decrease in crystal size with narrow crystal size distribution (CSD) and increase in nucleation rate than uninsonated solution, but have no effect on crystal morphology. Ultrasound promotes only α‐LM nucleation and no nucleation of either both α and β‐L is observed in all the 36 experiments carried out. The form of grown crystals is confirmed by powder X‐ray diffraction (PXRD) and their thermal behaviour is studied by differential scanning calorimetry (DSC) analyses. The purity of the grown crystals is determined using automatic digital polarimeter.
A strain gauge analysis comparing 4‐unit veneered zirconium dioxide implant‐borne fixed dental prosthesis on engaging and non‐engaging abutments before and after torque application
Authors: Epprecht Alyssa , Zeltner Marco , Benic Goran , Özcan Mutlu 
Published: February 2018

AbstractThis study quantified the strain development after inserting implant‐borne fixed dental prosthesis (FDP) to various implant–abutment joints. Two bone‐level implants (∅ = 4.1 mm, RC, SLA 10 mm, Ti, Straumann) were inserted in polyurethane models (N = 3) in the area of tooth nos 44 and 47. Four‐unit veneered zirconium dioxide FDPs (n = 2) were fabricated, one of which was fixed on engaging (E; RC Variobase, ∅ = 4.5 mm, H = 3.5 mm) and the other on non‐engaging (NE) abutments (RC Variobase, ∅ = 4.5 mm, H = 5.5 mm). One strain gauge was bonded to the occlusal surface of pontic no. 46 on the FDP and the other two on the polyurethane model. Before (baseline) and after torque (35 Ncm), strain values were recorded three times. Data were analyzed using Kruskal–Wallis and Mann–Whitney U tests (α = 0.05). Mean strain values presented significant increase after torque for both E and NE implant–abutment connection type (baseline: E = 4.33 ± 4.38; NE = 4.85 ± 4.85; torque: E = 196.56 ± 188.02; NE = 275.63 ± 407.7; p < .05). Mean strain values based on implant level presented significant increase after torque for both E and NE implant–abutment connection (baseline: E = 4.94 ± 5.29; NE = 5.78 ± 5.69; torque: E = 253.78 ± 178.14; NE = 347.72 ± 493.06; p < .05). The position of the strain gauge on implants (p = .895), FDP (p = .275), and abutment connection type (p = .873) did not significantly affect the strain values. Strain levels for zirconium dioxide implant‐borne FDPs were not affected by the implant–abutment connection type.
Seismic response analysis of reinforced concrete frames using inelasticity‐separated fiber beam‐column model
Authors: Li Gang , Yu Ding‐Hao , Li Hong‐Nan 
Published: February 2018

SummaryEvaluating the inelastic seismic response of structures accurately is of great importance in earthquake engineering and generally requires refined simulation, which is a time‐consuming process. Because the material nonlinearity generally occurs in a small part of the whole structure, many researches focus on taking advantage of this characteristic to improve the computational efficiency and the inelasticity‐separated finite element method (IS‐FEM) proposed recently provide a generic finite element formulation for solving this kind of problems efficiently. Although the fiber beam‐column element is widely used for the simulation of reinforced concrete (RC) framed structures, the inelastic deformation is often detected in a large part of the numerical model under earthquake excitation so that it is hard to achieve high efficient computation when applying the IS‐FEM to the inelastic response analysis of RC fiber models directly. In this paper, a new numerical scheme for seismic response analysis of RC framed structures model by fiber beam‐column element is proposed based on the IS‐FEM. To implement the RC fiber model for use in IS‐FEM and improve the computational performance of proposed scheme, a method of identifying the local domains with severe section inelasticity level is proposed and a modified Kent‐Park concrete material model is developed. Because the Woodbury formula is adopted as the solver, the global stiffness matrix can keep unchanged throughout the analysis and the main computational effort is only invested on a small matrix representing local inelastic behavior. The numerical examples demonstrate the validity and efficiency of the proposed scheme.
The handaxe reconsidered
Authors: Wynn Thomas , Gowlett John 
Published: February 2018

AbstractThe Acheulean handaxe is one of the longest‐known and longest‐surviving artifacts of the Palaeolithic and, despite its experimentally tested functionality, is often regarded as puzzling. It is unnecessary to invoke a unique‐for‐mammals genetic mechanism to explain the handaxe phenomenon. Instead, we propose that two nongenetic processes are sufficient. The first is a set of ergonomic design principles linked to the production of sturdy, hand‐held cutting tools in the context of a knapped‐stone technology that lacked hafting. The second is an esthetic preference for regular forms with gradual curves and pleasing proportions. Neither process is a cultural meme but, operating together in a cultural context, they can account for all of the supposedly puzzling time‐space patterns presented by handaxes.
The role of play objects and object play in human cognitive evolution and innovation
Authors: Riede Felix , Johannsen Niels N. , Högberg Anders , Nowell April , Lombard Marlize 
Published: February 2018

AbstractIn this contribution, we address a major puzzle in the evolution of human material culture: If maturing individuals just learn their parental generation's material culture, then what is the origin of key innovations as documented in the archeological record? We approach this question by coupling a life‐history model of the costs and benefits of experimentation with a niche‐construction perspective. Niche‐construction theory suggests that the behavior of organisms and their modification of the world around them have important evolutionary ramifications by altering developmental settings and selection pressures. Part of Homo sapiens' niche is the active provisioning of children with play objects — sometimes functional miniatures of adult tools — and the encouragement of object play, such as playful knapping with stones. Our model suggests that salient material culture innovation may occur or be primed in a late childhood or adolescence sweet spot when cognitive and physical abilities are sufficiently mature but before the full onset of the concerns and costs associated with reproduction. We evaluate the model against a series of archeological cases and make suggestions for future research.
Large eddy simulations of wall‐bounded flows using a simplified immersed boundary method and high‐order compact schemes
Authors: Tyliszczak A. , Ksiezyk M. 
Published: February 2018

SummaryThis paper presents a solution algorithm based on an immersed boundary (IB) method that can be easily implemented in high‐order codes for incompressible flows. The time integration is performed using a predictor‐corrector approach, and the projection method is used for pressure‐velocity coupling. Spatial discretization is based on compact difference schemes and is performed on half‐staggered meshes. A basic algorithm for body‐fitted meshes using the aforementioned solution method was developed by A. Tyliszczak (see article “A high‐order compact difference algorithm for half‐staggered grids for laminar and turbulent incompressible flows” in Journal of Computational Physics) and proved to be very accurate. In this paper, the formulated algorithm is adapted for use with the IB method in the framework of large eddy simulations. The IB method is implemented using its simplified variant without the interpolation (stepwise approach). The computations are performed for a laminar flow around a 2D cylinder, a turbulent flow in a channel with a wavy wall, and around a sphere. Comparisons with literature data confirm that the proposed method can be successfully applied for complex flow problems. The results are verified using the classical approach with body‐fitted meshes and show very good agreement both in laminar and turbulent regimes. The mean (velocity and turbulent kinetic energy profiles and drag coefficients) and time‐dependent (Strouhal number based on the drag coefficient) quantities are analyzed, and they agree well with reference solutions. Two subfilter models are compared, ie, the model of Vreman (see article “An eddy‐viscosity subgrid‐scale model for turbulent shear flow: algebraic theory and applications” in Physics and Fluids) and σ model (Nicoud et al, see article “Using singular values to build a subgrid‐scale model for large eddy simulations” in Physics and Fluids). The tests did not reveal evident advantages of any of these models, and from the point of view of solution accuracy, the quality of the computational meshes turned out to be much more important than the subfilter modeling.
Lake Mead Intake No 3 Tunnel – Design considerations and construction experience
Authors: Anagnostou Georg , Schuerch Roberto , Perazzelli Paolo 
Published: February 2018

AbstractThis paper presents the pre‐construction evaluation of the ground for the Lake Mead Intake No 3 Tunnel and the experience gained from the project, which had the aim of maintaining water supplies for the Las Vegas greater metropolitan area. The construction of this tunnel using a dual‐mode slurry shield represents a major engineering achievement, which pushed back the boundaries of closed shield tunnelling: Overcoming an extended fault zone under high hydrostatic pressure in the metamorphic rocks and mucking‐out difficulties associated with high rates of water inflow in the sedimentary rocks necessitated closed‐mode operation over about 2 km at unprecedentedly high face pressures of up to 14 bar.