bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstructing Plate Boundaries in the Jurassic Neo‐Tethys From the East and West Vardar Ophiolites (Greece and Serbia)
Authors: Maffione Marco , van Hinsbergen Douwe J. J.
Published: February 2018

Jurassic subduction initiation in the Neo‐Tethys Ocean eventually led to the collision of the Adria‐Africa and Eurasia continents and the formation of an ~6,000 km long Alpine orogen spanning from Iberia to Iran. Reconstructing the location and geometry of the plate boundaries of the now disappeared Neo‐Tethys during the initial moments of its closure is instrumental to perform more realistic plate reconstructions of this region, of ancient ocean basins in general, and on the process of subduction initiation. Neo‐Tethyan relics are preserved in an ophiolite belt distributed above the Dinaric‐Hellenic fold‐thrust belt. Here we provide the first quantitative constraints on the geometry of the spreading ridges and trenches active in the Jurassic Neo‐Tethys using a paleomagnetically based net tectonic rotation analysis of sheeted dykes and dykes from the West and East Vardar Ophiolites of Serbia (Maljen and Ibar) and Greece (Othris, Pindos, Vourinos, and Guevgueli). Based on our results and existing geological evidence, we show that initial Middle Jurassic (~175 Ma) closure of the western Neo‐Tethys was accommodated at a N‐S trending, west dipping subduction zone initiated near and parallel to the spreading ridge. The West Vardar Ophiolites formed in the forearc parallel to this new trench. Simultaneously, the East Vardar Ophiolites formed above a second N‐S to NW‐SE trending subduction zone located close to the European passive margin. We tentatively propose that this second subduction zone had been active since at least the Middle Triassic, simultaneously accommodating the closure of the Paleo‐Tethys and the back‐arc opening of Neo‐Tethys.
Cilia‐Inspired Flexible Arrays for Intelligent Transport of Viscoelastic Microspheres
Authors: Ben Shuang , Tai Jun , Ma Han , Peng Yun , Zhang Yuan , Tian Dongliang , Liu Kesong , Jiang Lei
Published: February 2018

Anisotropic microstructures are widely used by being cleverly designed to achieve important functions. Mammals' respiratory tract is filled with dense cilia that rhythmically swing back and forth in a unidirectional wave to propel mucus and harmful substances out of the lung through larynx. Inspired by the ciliary structure and motion mechanism of the respiratory tract systems, a viscoelastic microsphere transporting strategy based on integration of airway cilium‐like structure and magnetically responsive flexible conical arrays is demonstrated. Under external magnetic fields, the viscoelastic microspheres can be directionally and continuously transported alongside the swing of the cilia‐like arrays that contain magnetic particles. This work provides a promising route for the design of advanced medical applications in directional transport of microspheres, drug delivery systems, ciliary dyskinesia treating, and self‐cleaning without liquid.
Protoporphyrin IX (PpIX)‐Coated Superparamagnetic Iron Oxide Nanoparticle (SPION) Nanoclusters for Magnetic Resonance Imaging and Photodynamic Therapy
Authors: Yan Lesan , Amirshaghaghi Ahmad , Huang Dennis , Miller Joann , Stein Joel M. , Busch Theresa M. , Cheng Zhiliang , Tsourkas Andrew
Published: February 2018

The ability to produce nanotherapeutics at large‐scale with high drug loading efficiency, high drug loading capacity, high stability, and high potency is critical for clinical translation. However, many nanoparticle‐based therapeutics under investigation suffer from complicated synthesis, poor reproducibility, low stability, and high cost. In this work, a simple method for preparing multifunctional nanoparticles is utilized that act as both a contrast agent for magnetic resonance imaging and a photosensitizer for photodynamic therapy for the treatment of cancer. In particular, the photosensitizer protoporphyrin IX (PpIX) is used to solubilize small nanoclusters of superparamagnetic iron oxide nanoparticles (SPIONs) without the use of any additional carrier materials. These nanoclusters are characterized with a high PpIX loading efficiency; a high loading capacity, stable behavior; high potency; and a synthetic approach that is amenable to large‐scale production. In vivo studies of photodynamic therapy (PDT) efficacy show that the PpIX‐coated SPION nanoclusters lead to a significant reduction in the growth rate of tumors in a syngeneic murine tumor model compared to both free PpIX and PpIX‐loaded poly(ethylene glycol)‐polycaprolactone micelles, even when injected at 1/8th the dose. These results suggest that the nanoclusters developed in this work can be a promising nanotherapeutic for clinical translation.
Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3‐Disubstituted Phthalans
Authors: Nath Utpal , Chowdhury Deepan , Pan Subhas Chandra
Published: February 2018

The first nonenzymatic DKR reaction of hemithioacetals is developed. Hemithioacetals were formed in situ via thiol addition and subsequently underwent an intramolecular oxa‐Michael reaction. The scope of the reaction was quite broad ranging from aliphatic to aromatic substituents and 1,3‐disubstituted‐1,3‐dihyroisobenzofuran products were obtained in good yields with moderate diastereoselectivities and high enantioselectivities.

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Self‐Stabilized Hyaluronate Nanogel for Intracellular Codelivery of Doxorubicin and Cisplatin to Osteosarcoma
Authors: Zhang Yi , Wang Feng , Li Mingqiang , Yu Zhiqiang , Qi Ruogu , Ding Jianxun , Zhang Zhiyu , Chen Xuesi
Published: February 2018

Osteosarcoma is one of the most serious bone malignancies with rapid speed of deterioration and low survival rate in children and teenagers. Chemotherapy is an important treatment for osteosarcoma, while the conventional small‐molecule therapeutics exhibit low efficacies and severe side effects in the clinic. Drug‐delivery platforms based on nanotechnology, particularly for self‐stabilized delivery platforms with prolonged blood circulation, enhanced intratumoral accumulation, improved antitumor efficacy, and diminished side effects, may break the deadlock on osteosarcoma chemotherapy. Here, a cisplatin (CDDP)‐crosslinked hyaluronic acid (HA) nanogel (CDDPHANG) is prepared for effective delivery of doxorubicin (DOX) to treat osteosarcoma. Importantly, both DOX and CDDP have led clinically used antitumor drugs, and CDDP acts as a crosslinker and ancillary anticarcinogen to prevent the premature release of DOX and to achieve synergistic therapeutic performance. Because of the enhanced stability of the nanogel, this CDDP‐crosslinked DOX‐loaded nanomedicine (CDDPHANG/DOX) exhibits an obviously prolonged circulation time compared to free drugs. Moreover, after valid tumor accumulation, DOX and CDDP are synergistically delivered into the tumor cells and synchronously released into the intracellular acidic environment. Based on the synergistic apoptosis‐inducing effects of DOX and CDDP, CDDPHANG/DOX reveals an evidently enhanced antitumor efficacy compared to free drugs and their combination, indicating its great prospects for the chemotherapy of osteosarcoma.
Small trees, big problems: Comparative leaf function under extreme edaphic stress
Authors: Cary Katharine L. , Pittermann Jarmila
Published: February 2018

Premise of the Study

The pygmy forest, a plant community of severely stunted conifers and ericaceous angiosperms, occurs on patches of highly acidic, nutrient‐poor soils along the coast of Northern California, USA. This system is an excellent opportunity to study the effect of severe nutrient deficiency on leaf physiology in a naturally‐occurring ecosystem. In this study, we seek to understand the physiological mechanisms stunting the plants' growth and their implications for whole plant function.

Methods

We measured 14 traits pertaining to leaf photosynthetic function or physical structure on seven species. Samples were taken from the pygmy forest community and from conspecifics growing on higher‐nutrient soils, where trees may grow over 30 m tall.

Key Results

Pygmy plants of most species maintained similar area‐based photosynthetic and stomatal conductance rates to conspecific controls, but had lower specific leaf area (leaf area divided by dry weight), lower percent nitrogen, and less leaf area relative to xylem growth. Sequoia sempervirens, a species rare in the pygmy forest, had a categorically different response from the more common plants and had remarkably low photosynthetic rates.

Conclusions

Pygmy plants were not stunted by low photosynthetic rates on a leaf‐area basis; instead, several species had restricted whole‐plant photosynthesis due to low leaf area production. Pygmy plants of all species showed signs of greater carbon investment in their leaves and higher production of nonphotosynthetic leaf tissue, further contributing to slow growth rates.
Sleep in a comparative context: Investigating how human sleep differs from sleep in other primates
Authors: Nunn Charles L. , Samson David R.
Published: February 2018

Objectives

Primates vary in their sleep durations and, remarkably, humans sleep the least per 24‐hr period of the 30 primates that have been studied. Using phylogenetic methods that quantitatively situate human phenotypes within a broader primate comparative context, we investigated the evolution of human sleep architecture, focusing on: total sleep duration, rapid eye movement (REM) sleep duration, non‐rapid eye movement (NREM) sleep duration, and proportion of sleep in REM.

Materials and Methods

We used two different Bayesian methods: phylogenetic prediction based on phylogenetic generalized least squares and a multistate Onrstein‐Uhlenbeck (OU) evolutionary model of random drift and stabilizing selection.

Results

Phylogenetic prediction confirmed that humans sleep less than predicted for a primate of our body mass, predation risk, brain size, foraging needs, sexual selection, and diet. These analyses further revealed that humans pack an unexpectedly higher proportion of REM sleep within a shorter overall sleep duration, and do so by reducing NREM sleep (rather than increasing REM). The OU model generally confirmed these findings, with shifts along the human lineage inferred for TST, NREM, and proportion of REM, but not for REM.

Discussion

We propose that the risks and opportunity costs of sleep are responsible for shorter sleep durations in humans, with risks arising from terrestrial sleep involving threats from predators and conspecifics, and opportunity costs because time spent sleeping could be used for learning, creating material objects, and socializing.
Surface smoothing, decimation, and their effects on 3D biological specimens
Authors: Veneziano Alessio , Landi Federica , Profico Antonio
Published: February 2018

Objective

Smoothing and decimation filters are commonly used to restore the realistic appearance of virtual biological specimens, but they can cause a loss of topological information of unknown extent. In this study, we analyzed the effect of smoothing and decimation on a 3D mesh to highlight the consequences of an inappropriate use of these filters.

Materials and methods

Topological noise was simulated on four anatomical regions of the virtual reconstruction of an orangutan cranium. Sequential levels of smoothing and decimation were applied, and their effects were analyzed on the overall topology of the 3D mesh and on linear and volumetric measurements.

Results

Different smoothing algorithms affected mesh topology and measurements differently, although the influence on the latter was generally low. Decimation always produced detrimental effects on both topology and measurements. The application of smoothing and decimation, both separate and combined, is capable of recovering topological information.

Conclusion

Based on the results, objective guidelines are provided to minimize information loss when using smoothing and decimation on 3D meshes.
Three‐dimensional (3D) geometric morphometric analysis of human premolars to assess sexual dimorphism and biological ancestry in Australian populations
Authors: Yong Robin , Ranjitkar Sarbin , Lekkas Dimitra , Halazonetis Demetrios , Evans Alistair , Brook Alan , Townsend Grant
Published: February 2018

Objectives

This study aimed to investigate size and shape variation of human premolars between Indigenous Australians and Australians of European ancestry, and to assess whether sex and ancestry could be differentiated between these groups using 3D geometric morphometrics.

Materials and Methods

Seventy dental casts from each group, equally subdivided by sex, were scanned using a structured‐light scanner. The 3D meshes of upper and lower premolars were processed using geometric morphometric methods. Seventy‐two landmarks were recorded for upper premolars and 50 landmarks for lower premolars. For each tooth type, two‐way ANOVA was used to assess group differences in centroid size. Shape variations were explored using principal component analysis and visualized using 3D morphing. Two‐way Procrustes ANOVA was applied to test group differences for ancestry and sex, and a “leave‐one‐out” discriminant function was applied to assess group assignment.

Results

Centroid size and shape did not display significant difference between the sexes. Centroid size was larger in Indigenous Australians for upper premolars and lower second premolars compared to the Australians of European ancestry. Significant shape variation was noted between the two ancestral groups for upper premolars and the lower first premolar. Correct group assignment of individual teeth to their ancestral groups ranged between 80.0 and 92.8% for upper premolars and 60.0 and 75.7% for lower premolars.

Discussion

Our findings provide evidence of significant size and shape variation in human premolars between the two ancestral groups. High classification rates based on shape analysis of upper premolars highlight potential application of geometric morphometrics in anthropological, bioarcheological and forensic contexts.
A multivariate ecogeographic analysis of macaque craniodental variation
Authors: Grunstra Nicole D. S. , Mitteroecker Philipp , Foley Robert A.
Published: February 2018

Objectives

To infer the ecogeographic conditions that underlie the evolutionary diversification of macaques, we investigated the within‐ and between‐species relationships of craniodental dimensions, geography, and environment in extant macaque species. We studied evolutionary processes by contrasting macroevolutionary patterns, phylogeny, and within‐species associations.

Materials and Methods

Sixty‐three linear measurements of the permanent dentition and skull along with data about climate, ecology (environment), and spatial geography were collected for 711 specimens of 12 macaque species and analyzed by a multivariate approach. Phylogenetic two‐block partial least squares was used to identify patterns of covariance between craniodental and environmental variation. Phylogenetic reduced rank regression was employed to analyze spatial clines in morphological variation.

Results

Between‐species associations consisted of two distinct multivariate patterns. The first represents overall craniodental size and is negatively associated with temperature and habitat, but positively with latitude. The second pattern shows an antero‐posterior tooth size contrast related to diet, rainfall, and habitat productivity. After controlling for phylogeny, however, the latter dimension was diminished. Within‐species analyses neither revealed significant association between morphology, environment, and geography, nor evidence of isolation by distance.

Discussion

We found evidence for environmental adaptation in macaque body and craniodental size, primarily driven by selection for thermoregulation. This pattern cannot be explained by the within‐species pattern, indicating an evolved genetic basis for the between‐species relationship. The dietary signal in relative tooth size, by contrast, can largely be explained by phylogeny. This cautions against adaptive interpretations of phenotype–environment associations when phylogeny is not explicitly modelled.
Morphological integration in the gorilla, chimpanzee, and human neck
Authors: Arlegi Mikel , Gómez‐Robles Aida , Gómez‐Olivencia Asier
Published: February 2018

Objectives

Although integration studies are important to understand the evolution of organisms' traits across phylogenies, vertebral integration in primates is still largely unexplored. Here we describe and quantify patterns of morphological integration and modularity in the subaxial cervical vertebrae (C3–C7) in extant hominines incorporating the potential influence of size.

Materials and Methods

Three‐dimensional landmarks were digitized on 546 subaxial cervical vertebrae from 141 adult individuals of Gorilla gorilla, Pan troglodytes, and Homo sapiens. Integration and modularity, and the influence of size effects, were quantified using geometric morphometric approaches.

Results

All subaxial cervical vertebrae from the three species show a strong degree of integration. Gorillas show the highest degree of integration; conversely, humans have the lowest degree of integration. Analyses of allometric regression residuals show that size is an important factor promoting integration in gorillas, with lesser influence in chimpanzees and almost no effect in humans.

Discussion

Results point to a likely ancestral pattern of integration in non‐human hominines, whereby the degree of integration decreases from cranial to caudal positions. Humans deviate from this pattern in the cranialmost (C3) and, to a lesser extent, in the caudalmost (C7) vertebrae, which are less integrated. These differences can be tentatively related to the emergence of bipedalism due to the presence of modern human‐like C3 in australopiths, which still preserve a more chimpanzee‐like C7.
Amyloid‐Polymorphie in der Energielandschaft der Faltung und Aggregation von Proteinen
Authors: Adamcik Jozef , Mezzenga Raffaele
Published: February 2018

Die Proteinfaltung umfasst eine Vielzahl an Schritten und Konformationen, in denen das sich faltende Protein unterschiedliche thermodynamische Zustände erprobt, die durch lokale Minima gekennzeichnet sind. Kinetisch festgelegte Intermediate des An‐ oder Aus‐Wegs sind metastabile Faltungsintermediate auf dem Weg zu den niedrigsten absoluten Energieminima, die als nativ gefalteter Zustand konstatiert wurden, in dem intramolekulare Wechselwirkungen dominieren, und der Amyloid‐Zustand, in dem intermolekulare Wechselwirkungen dominieren. Diese Auffassung lässt allerdings die in Amyloid‐Spezies vorzufindende, reichhaltige Polymorphie unberücksichtigt. Dieser Kurzaufsatz gibt einen Überblick über die Energielandschaft der Proteinfaltung unter Berücksichtigung der neuesten Erkenntnisse bei der Identifikation spezieller Umwandlungen zwischen unterschiedlichen Amyloid‐Polymorphien. Die beobachteten Umwandlungen, wie “verdrillte Bänder→Kristalle” oder “helikale Bänder→Nanoröhren”, sowie verbotene Umwandlungen, wie “helikale Bänder↛Kristall”, werden diskutiert und innerhalb der Energielandschaft der Proteinfaltung und –aggregation positioniert. Abschließend werden Amyloid‐Kristalle als Grundzustand der Energielandschaft der Proteinfaltung und ‐aggregation identifiziert.
Synergistic Photoredox Catalysis and Organocatalysis for Inverse Hydroboration of Imines
Authors: Zhou Nengneng , Yuan Xiang‐Ai , Zhao Yue , Xie Jin , Zhu Chengjian
Published: February 2018

The first catalytic inverse hydroboration of imines with N‐heterocyclic carbene (NHC) boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination provides a promising platform for promoting NHC‐boryl radical chemistry under sustainable and radical‐initiator‐free conditions. The highly important functional‐group compatibility and possible application in late‐stage hydroborations represent an important step forward to an enhanced α‐amino organoboron library.
Coumarin Photocaging Groups Modified with an Electron‐Rich Styryl Moiety at the 3‐Position: Long‐Wavelength Excitation, Rapid Photolysis, and Photobleaching
Authors: Lin Qiuning , Yang Lipeng , Wang Zhiqiang , Hua Yujie , Zhang Dasheng , Bao Bingkun , Bao Chunyan , Gong Xueqing , Zhu Linyong
Published: February 2018

A new class of coumarin photocaging groups modified with an electron‐rich styryl moiety at the 3‐position was constructed. The large π‐conjugated structure and stabilization of the carbocation intermediates by electron donors endowed the new photocaging groups with excellent long‐wavelength absorption, large two‐photon absorption cross‐sections, and high uncaging quantum yields. Moreover, the new photocaging groups displayed unique photobleaching properties after photocleavage as a result of the intramolecular cyclization rearrangement of a carbocation intermediate to form five‐membered ring byproducts and block the styryl conjugation at the 3‐position. These superior properties of the new photocaging groups are extremely beneficial for high‐concentration samples and thick specimens, thus extending the application of photocaging groups in many fields.
Synthesis of a Helical Bilayer Nanographene
Authors: Evans Paul J. , Ouyang Jiangkun , Favereau Ludovic , Crassous Jeanne , Fernández Israel , Perles Josefina , Martín Nazario
Published: February 2018

A rigid, inherently chiral bilayer nanographene has been synthesized as both the racemate and enantioenriched M isomer (with 93 % ee) in three steps from established helicenes. This folded nanographene is composed of two hexa‐peri‐hexabenzocoronene layers fused to a [10]helicene, with an interlayer distance of 3.6 Å as determined by X‐ray crystallography. The rigidity of the helicene linker forces the layers to adopt a nearly aligned AA‐stacked conformation, rarely observed in few‐layer graphene. By combining the advantages of nanographenes and helicenes, we have constructed a bilayer system of 30 fused benzene rings that is also chiral, rigid, and remains soluble in common organic solvents. We present this as a molecular model system of bilayer graphene, with properties of interest in a variety of potential applications.
Co‐assembly of Polyoxometalates and Zwitterionic Amphiphiles into Supramolecular Hydrogels: From Crystalline Fibrillar to Amorphous Micellar Networks
Authors: Wu Aoli , Gao Xinpei , Sun Panpan , Lu Fei , Zheng Liqiang
Published: February 2018

Gelation mechanism is of utmost importance to the rational design of supramolecular hydrogelators. Although both kinetic and thermodynamic controlled self‐assembly processes have been widely studied in hydrogels, the formation relationship between crystalline and amorphous gel networks still remains ambiguous. Herein, a gelation transformation from a kinetic to a thermodynamic process was achieved by balancing the rigidity and flexibility of the inorganic–organic co‐assemblies. By using polyoxometalates and zwitterionic amphiphiles, the transition morphologies between crystalline and amorphous hydrogel networks were evidenced for the first time, as ordered wormlike micelles. Given the versatile applications of hydrogels in biological systems and materials science, these findings may highlight the potential of inorganic–organic binary supramolecular hydrogelators and fill in the blank between kinetic and thermodynamic controlled gelation processes.
Entropy‐Driven Diastereoselectivity Improvement in the Paternò–Büchi Reaction of 1‐Naphthyl Aryl Ethenes with a Chiral Cyanobenzoate through Remote Alkylation
Authors: Nagasaki Keisuke , Inoue Yoshihisa , Mori Tadashi
Published: February 2018

The precise stereocontrol of photocycloaddition reactions is still a significant challenge owing to their mechanistic complexity and the involvement of highly reactive and short‐lived intermediates. Attempts have hitherto been made through structural modifications, mostly by introducing steric conflicts, to increase the difference between the enthalpic barriers. Herein, we show that entropy plays a crucial role in influencing the diastereoselectivity of a Paternò–Büchi reaction. Remote meta alkylation of the donor caused nominal changes in its photophysical properties as well as those of the exciplexes derived thereof. Nevertheless, the diastereomeric excess of the oxetane product was greatly improved by about 40 %. This enhancement, which is not accompanied by any significant changes in the photophysical properties, is difficult to rationalize by conventional enthalpic control concepts based on repulsive steric and/or attractive intermolecular interactions as well as electronic perturbations. Differential activation parameters and compensatory enthalpy–entropy relationships revealed that the diastereoselectivity enhancement is not simply enthalpic but also entropic in origin.
Chitosan‐Supported Ni particles: An Efficient Nanocatalyst for Direct Amination of Phenols
Authors: Hajipour Abdol R. , Abolfathi Parisa
Published: February 2018

A practical method for the direct amination of phenols using 2,4,6‐trichloro‐1,3,5‐triazine (TCT) as an efficient promotor for the activation of phenols in the presence of an efficient and recyclable heterogeneous catalyst prepared by immobilization of nickel particles on triazole modified chitosan is described. This heterogeneous catalyst has demonstrated a promising activity for the conversion of phenolic compounds to their corresponding amine under mild conditions. Moreover, the obtained catalyst can be reused in five consecutive runs with consistent catalytic activity.
Peroxidative catalytic oxidation of alcohols catalyzed by heterobinuclear vanadium(V) complexes using H2O2 as terminal oxidizing agents
Authors: Kurbah Sunshine D. , Asthana M. , Syiemlieh Ibanphylla , Lal Ram A.
Published: February 2018

Here we report the catalytic oxidation of benzylic alcohol, hetero‐aryl alcohols and propargylic alcohols to their corresponding carbonyl compound using heterobimetallic sodium‐dioxidovanadium(V) complexes. The present catalytic oxidation studies proceed at 70 °C using H2O2 as terminal oxidant. During the whole process, the complexes react with hydrogen peroxide to form peroxo‐vanadium(V) species. The present study shows the heterogeneity of pre‐catalyst which could be easily recovered and moreover isolation of product is very simple.
Au(III) complexes loaded pH‐responsive magnetic nanogels for cancer therapy
Authors: Rezaei Seyed Jamal Tabatabaei , Norouzi Khadijeh , Hesami Ali , Malekzadeh Asemeh Mashhadi , Ramazani Ali , Amani Vahid , Ahmadi Roya
Published: February 2018

A novel pH‐responsive magnetic nanogels were developed with the aim of targeted delivering and simultaneously releasing of newly synthesized Au(III)‐based anticancer drug, Au(1,7‐Phen)Br3. The obtained nanogels were characterized by FT‐IR, DLS, EDAX, TEM, XRD, ICP‐Ms and MRI. The TEM images showed that the nanogels had a spherical shape with a mean diameter of 20 nm. The in vitro release studies of Au (III)‐loaded nanogels showed a pH‐triggered controlled release of drugs. The in vitro cytotoxicity assay of samples to human cervical cancer HeLa cell lines indicated that the Au(III)‐loaded magnetic nanogels exert higher cytotoxicity in comparison with free Au(III) complex. Fluorescent microscope images indicated that these magnetic nanogels possessed notable cell specific targeting in vitro in the presence of an external magnetic field. The results show that this superparamagnetic nanocarrier is a promising candidate for inhibiting growth of tumor cells.
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

A 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

A 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

The 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.
Pricing and hedging barrier options
Authors: Rosalino Estevão , da Silva Allan J. , Baczynski Jack , Leão Dorival
Published: February 2018

European options are a significant financial product. Barrier options, in turn, are European options with a barrier constraint. The investor may pay less buying the barrier option obtaining the same result as that of the European option whenever the barrier is not breached. Otherwise, the option's payoff cancels. In this paper, we obtain closed‐form expressions of the exact no‐arbitrage prices, delta hedges, and gammas of a call option with a moving barrier that tracks the prices of the risk‐free asset. Besides the interest in its own right, this class of options constitutes the core element to obtain, via an original and simple technique, the closed‐form expressions for the estimates of the prices of call options with barriers of arbitrary shape. Equally important is the fact that a bound for the worst associated error is provided, so the investor can evaluate beforehand if the accuracy provided is according to his/her needs or not. Discrete monitored barrier provisions are also allowed in the estimates. Simulations are performed illustrating the accuracy of the estimates. A quality of the aforementioned procedures is that the time consumed in computations is very small. In turn, we observe that the approximate prices, delta hedges, and gammas of the barrier option associated to the risk‐free asset, obtained via a PDE approach in conjunction with a good finite difference method, converge to the closed‐form expressions of the prices, hedges, and gammas of the option. This attests the correctness of the analytical results.
Unspecified distributions in single disorder problem
Authors: Sarnowski Wojciech , Szajowski Krzysztof
Published: February 2018

The purpose of this article is to present the issue of algorithms of the change detection model for the political business cycle. Political business cycle issue is interesting in the context of the current political situation in Europe, ie, the progressive integration of the European Union countries and the wave of financial problems that affected the state, which has been regarded so far as economically stable. Monitoring of this phenomenon is characterized by the fact that we do not usually have full information about the behavior of business indexes before and after the change. It is assumed that we are observing a stochastic sequence whose mathematical model predicts a sudden change. The process is Markovian when the change moment is given. The initial problem of disorder detection is transformed to the optimal stopping of the observed sequence. In order to construct an algorithm for estimating the moment of change, we transform the task into an equivalent problem of optimal stopping based on the observed magnitude and some statistics. The analysis obtained from the transformation of the problem is the source of the change point estimation algorithms. The formula for the optimal decision functions is derived.
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

Magnetic 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

An 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

The 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

Although 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

In 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

This 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

In 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

This 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.
Molecular diagnostic techniques in cytopathology: From the bench to the patient's bedside
Authors: Díaz del Arco Cristina , Fernández Aceñero Mª Jesús
Published: February 2018

Molecular techniques are increasingly used in everyday practice for patient diagnosis and also to guide therapy. Their application in cytological specimens can allow a more cost‐effective management with fewer risks. However, standardized protocols are needed to guarantee accurate and reproducible results. We herein report five practical examples of the application of ancillary techniques in cytopathology and review the literature on the issue, highlighting the practical aspects of sample management.
Copper(I)–Dioxygen Reactivity in the Isolated Cavity of a Nanoscale Molecular Architecture
Authors: Paria Sayantan , Morimoto Yuma , Ohta Takehiro , Okabe Shinsuke , Sugimoto Hideki , Ogura Takashi , Itoh Shinobu
Published: February 2018

Copper(I) and copper(II) complexes supported by a bulky tetradentate N4 ligand, [CuI(TIPT3tren)(CH3CN)]ClO4 (1) and [CuII(TIPT3tren)Cl]BF4 (2), were synthesized and characterized, where TIPT is 2,2′′,6,6′′‐tetraisopropyl‐1,3′:5′,1′′‐terphenyl and tren is tris(2‐aminoethyl)amine. The copper(II) chloride complex 2 exhibits a trigonal‐bipyramidal structure, as usually observed for the tren ligand system, in which the chloride ligand occupies an axial position and is encapsulated in an isolated cavity consisting of three TIPT substituents. Such a trigonal‐bipyramidal structure is stabilized in acetone, in which hydrogen‐bonding interactions between the anilino N–H groups and the oxygen atom of the acetone molecules, entrapped in the hydrophobic clefts between the TIPT substituents, play an important role. The reaction of copper(I) complex 1 and O2 in an acetone‐containing solvent at –110 °C gave end‐on copper(II) superoxide complex 3 together with putative side‐on copper(III) peroxide complex 4, as was evident from detailed studies by variable‐temperature UV/Vis, resonance Raman, and 1H and 2H NMR spectroscopy. The formation of 3 and 4 was also validated by DFT calculations.