bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversible Magnetic Agglomeration: A Mechanism for Thermodynamic Control over Nanoparticle Size
Authors: Bleier Grant C. , Watt John , Simocko Chester K. , Lavin Judith M. , Huber Dale L.
Published: March 2018

We present a method for the synthesis and precise size control of magnetic nanoparticles in a reversible magnetic agglomeration mechanism. In this approach, nanoparticles nucleate and grow until a critical susceptibility is reached, in which magnetic attraction overcomes dispersive forces, leading to agglomeration and precipitation. This phase change in the system arrests nanoparticle growth and gives true thermodynamic control over the size of nanoparticles. We then show that increasing the alkyl chain length of the surfactant, and hence increasing steric stabilization, allows nanoparticles to grow to larger sizes before agglomeration occurs. Therefore, simply by choosing the correct surfactant, the size and magnetic properties of iron nanoparticles can be tailored for a particular application. With the continuous addition of the precursor solution, we can repeat the steps of nucleation, growth, and magnetic agglomeration indefinitely, making the approach suitable for large scale syntheses.
Catalytic Enantioselective 1,3‐Alkyl Shift in Alkyl Aryl Ethers: Efficient Synthesis of Optically Active 3,3′‐Diaryloxindoles
Authors: Gade Amol B. , Bagle Pradip N. , Shinde Popat S. , Bhardwaj Vipin , Banerjee Subhrashis , Chande Ajit , Patil Nitin T.
Published: March 2018

Reported is the first organocatalytic asymmetric 1,3‐alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3′‐diaryloxindoles using a chiral Brønsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3′‐diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay.
Charge Transport between Coupling Colloidal Perovskite Quantum Dots Assisted by Functional Conjugated Ligands
Authors: Dai Jinfei , Xi Jun , Li Lu , Zhao JingFeng , Shi Yifei , Zhang Wenwen , Ran Chenxin , Jiao Bo , Hou Xun , Duan Xinhua , Wu Zhaoxin
Published: March 2018

Long alkyl‐chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light‐emitting diodes (LEDs). The trade‐off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr3) QDs with a conjugated alkyl‐amine, 3‐phenyl‐2‐propen‐1‐amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA‐QDs films increased almost 22 times over that of OA‐QD films without compromising colloidal stability and photoluminescence. PPA‐QDs LEDs exhibit a maximum current efficiency of 9.08 cd A−1, which is 8 times of that of OA‐QDs LEDs (1.14 cd A−1). This work provides critical solution for the poor conductivity of QDs in applications of energy‐related devices.
Synthesis of Non‐Classical Arylated C‐Saccharides through Nickel/Photoredox Dual Catalysis
Authors: Dumoulin Audrey , Matsui Jennifer K. , Gutiérrez‐Bonet Álvaro , Molander Gary A.
Published: March 2018

The development of synthetic tools to introduce saccharide derivatives into functionally complex molecules is of great interest, particularly in the field of drug discovery. Herein, we report a new route toward highly functionalized, arylated saccharides, which involves nickel‐catalyzed cross‐coupling of photoredox‐generated saccharyl radicals with a range of aryl‐ and heteroaryl bromides, triggered by an organic photocatalyst. In contrast to existing methods, the mild reaction conditions achieve arylation of saccharide motifs while leaving the anomeric carbon available, thus providing access to a class of arylated glycosides that has been underexplored until now. To demonstrate the potential of this strategy in late‐stage functionalization, a variety of structurally complex molecules incorporating saccharide moieties were synthesized.
Biosynthesis of the Polycyclic System in the Antifungal HSAF and Analogues from Lysobacter enzymogenes
Authors: Li Yaoyao , Wang Haoxin , Liu Yan , Jiao Yujie , Li Shanren , Shen Yuemao , Du Liangcheng
Published: March 2018

The biocontrol agent Lysobacter enzymogenes produces polycyclic tetramate macrolactams (PoTeMs), including the antifungal HSAF. To elucidate the biosynthesis of the cyclic systems, we identified eleven HSAF precursors/analogues with zero, one, two, or three rings through heterologous expression of the HSAF gene cluster. A series of combinatorial gene expression and deletion experiments showed that OX3 is the “gatekeeper” responsible for the formation of the first 5‐membered ring from lysobacterene A, OX1 and OX2 are responsible for formation of the second ring but with different selectivity, and OX4 is responsible for formation of the 6‐membered ring. In vitro experiments showed that OX4 is an NADPH‐dependent enzyme that catalyzes the reductive cyclization of 3‐dehydroxy alteramide C to form 3‐dehydroxy HSAF. Thus, the multiplicity of OX genes is the basis for the structural diversity of the HSAF family, which is the only characterized PoTeM cluster that involves four redox enzymes in the formation of the cyclic system.
Revealing the Formation Mechanism of CsPbBr3 Perovskite Nanocrystals Produced via a Slowed‐Down Microwave‐Assisted Synthesis
Authors: Li Yanxiu , Huang He , Xiong Yuan , Kershaw Stephen V. , Rogach Andrey L.
Published: March 2018

We developed a microwave‐assisted slowed‐down synthesis of CsPbBr3 perovskite nanocrystals, which retards the reaction and allows us to gather useful insights into the formation mechanism of these nanoparticles, by examining the intermediate stages of their growth. The trends in the decay of the emission intensity of CsPbBr3 nanocrystals under light exposure are well correlated with their stability against decomposition in TEM under electron beam. The results show the change of the crystal structure of CsPbBr3 nanocrystals from a deficient and easier to be destroyed lattice to a well crystallized one. Conversely the shift in the ease of degradation sheds light on the formation mechanism, indicating first the formation of a bromoplumbate ionic scaffold, with Cs‐ion infilling lagging a little behind. Increasing the cation to halide ratio towards the stoichiometric level may account for the improved radiative recombination rates observed in the longer reaction time materials.
Biocatalytic Oxidation Reactions: A Chemist's Perspective
Authors: Dong JiaJia , Fernández‐Fueyo Elena , Hollmann Frank , Paul Caroline E. , Pesic Milja , Schmidt Sandy , Wang Yonghua , Younes Sabry , Zhang Wuyuan
Published: March 2018

Oxidation chemistry using enzymes is approaching maturity and practical applicability in organic synthesis. Oxidoreductases (enzymes catalysing redox reactions) enable chemists to perform highly selective and efficient transformations ranging from simple alcohol oxidations to stereoselective halogenations of non‐activated C−H bonds. For many of these reactions, no “classical” chemical counterpart is known. Hence oxidoreductases open up shorter synthesis routes based on a more direct access to the target products. The generally very mild reaction conditions may also reduce the environmental impact of biocatalytic reactions compared to classical counterparts. In this Review, we critically summarise the most important recent developments in the field of biocatalytic oxidation chemistry and identify the most pressing bottlenecks as well as promising solutions.
Trimethylsilyl‐Protected Alkynes as Selective Cross‐Coupling Partners in Titanium‐Catalyzed [2+2+1] Pyrrole Synthesis
Authors: Chiu Hsin‐Chun , Tonks Ian A.
Published: March 2018

Trimethylsilyl (TMS)‐protected alkynes served as selective alkyne cross‐coupling partners in titanium‐catalyzed [2+2+1] pyrrole synthesis. Reactions of TMS‐protected alkynes with internal alkynes and azobenzene under the catalysis of titanium imido complexes yielded pentasubstituted 2‐TMS‐pyrroles with greater than 90 % selectivity over the other nine possible pyrrole products. The steric and electronic effects of the TMS group were both identified to play key roles in this highly selective pyrrole synthesis. This strategy provides a convenient method to synthesize multisubstituted pyrroles as well as an entry point for further pyrrole diversification through facile modification of the resulting 2‐silyl pyrrole products, as demonstrated through a short formal synthesis of the marine natural product lamellarin R.
Reaction of B2(o‐tol)4 with CO and Isocyanides: Cleavage of the C≡O Triple Bond and Direct C−H Borylations
Authors: Katsuma Yuhei , Tsukahara Nana , Wu Linlin , Lin Zhenyang , Yamashita Makoto
Published: March 2018

The reaction of highly Lewis acidic tetra(o‐tolyl)diborane(4) with CO afforded a mixture of boraindane and boroxine by the cleavage of the C≡O triple bond. 13C labeling experiments confirmed that the carbon atom in the boraindane stems from CO. Simultaneously, formation of boroxine 3 could be considered as borylene transfer to capture the oxygen atom from CO. The reaction of diborane(4) with tBu−NC afforded an azaallene, while the reaction with Xyl−NC furnished cyclic compounds by direct C−H borylations.
The Chemistry behind Catechol‐Based Adhesion
Authors: Saiz‐Poseu J. , Mancebo‐Aracil J. , Nador F. , Busqué F. , Ruiz‐Molina D.
Published: March 2018

The adhesion of some marine organisms to almost any kind of surface in wet conditions has aroused increasing interest in recent decades. Numerous fundamental studies have been performed to understand the scientific basis of this behaviour, with catechols having been found to play a key role. Several novel bio‐inspired adhesives and coatings with value‐added performances have been developed by taking advantage of the knowledge gained from these studies. To date there has been no detailed overview focusing exclusively on the complex mode of action of these materials. The aim of this Review is to present recent investigations that elucidate the origin of the strong and versatile adsorption capacities of the catechol moiety and the effects of extrinsic factors that play important roles in the overall adhesion process, such as pH value, solvent, and the presence of metal ions. The aim is to detail the chemistry behind the astonishing properties of natural and synthetic catechol‐based adhesive materials.
Highly Stereoselective Synthesis of 1,3‐Dienes through an Aryl to Vinyl 1,4‐Palladium Migration/Heck Sequence
Authors: Hu Tian‐Jiao , Li Meng‐Yao , Zhao Qian , Feng Chen‐Guo , Lin Guo‐Qiang
Published: March 2018

An efficient aryl to vinyl 1,4‐palladium migration/Heck sequence was developed for the stereoselective synthesis of 1,3‐dienes. High stereoselectivity was observed not only for 1,3‐dienes bearing two similar aryl groups at terminal positions, but also for those with configurations shown to be unfavorable with previous methods.
Ultrastable Imine‐Based Covalent Organic Frameworks for Sulfuric Acid Recovery: An Effect of Interlayer Hydrogen Bonding
Authors: Halder Arjun , Karak Suvendu , Addicoat Matthew , Bera Saibal , Chakraborty Amit , Kunjattu Shebeeb H. , Pachfule Pradip , Heine Thomas , Banerjee Rahul
Published: March 2018

A rapid and scalable synthesis of six new imine‐linked highly porous and crystalline COFs is presented that feature exceptionally high chemical stability in harsh environments including conc. H2SO4 (18 m), conc. HCl (12 m), and NaOH (9 m). This is because of the presence of strong interlayer C−H⋅⋅⋅N hydrogen bonding among the individual layers, which provides significant steric hindrance and a hydrophobic environment around the imine (−C=N−) bonds, thus preventing their hydrolysis in such an abrasive environment. These COFs were further converted into porous, crystalline, self‐standing, and crack‐free COF membranes (COFMs) with extremely high chemical stability for their potential applications for sulfuric acid recovery. The as‐synthesized COFMs exhibit unprecedented permeance for acetonitrile (280 Lm−2 h−1 bar−1) and acetone (260 Lm−2 h−1 bar−1).
High Electromagnetic Field Enhancement of TiO2 Nanotube Electrodes
Authors: Öner Ibrahim Halil , Querebillo Christine Joy , David Christin , Gernert Ulrich , Walter Carsten , Driess Matthias , Leimkühler Silke , Ly Khoa Hoang , Weidinger Inez M.
Published: March 2018

We present the fabrication of TiO2 nanotube electrodes with high biocompatibility and extraordinary spectroscopic properties. Intense surface‐enhanced resonance Raman signals of the heme unit of the redox enzyme Cytochrome b5 were observed upon covalent immobilization of the protein matrix on the TiO2 surface, revealing overall preserved structural integrity and redox behavior. The enhancement factor could be rationally controlled by varying the electrode annealing temperature, reaching a record maximum value of over 70 at 475 °C. For the first time, such high values are reported for non‐directly surface‐interacting probes, for which the involvement of charge‐transfer processes in signal amplification can be excluded. The origin of the surface enhancement is exclusively attributed to enhanced localized electric fields resulting from the specific optical properties of the nanotubular geometry of the electrode.
Ethylene diamine grafted nanoporous UiO‐66 as an efficient basic catalyst in the multi‐component synthesis of 2‐aminithiophenes
Authors: Erfaninia N. , Tayebee R. , Dusek M. , Amini M.M.
Published: March 2018

This study demonstrates ED‐UiO‐66 as a novel and effective solid nanoporous basic catalyst prepared through the amine grafting onto the pores of UiO‐66. The manufactured nanoparticles were identified by FT‐IR, XRD, TGA, FESEM, TEM, CHN and BET and the characterization results certified formation of a single phase nanoporous substance with the medium grain size less than 90 nm. The synthesized material was employed as an efficient catalyst for the preparation of 2‐aminotiophenes through the Gewald method. This thermochemically stable nanocatalyst was environmentally safe, reusable and economic. Therefore, this methodology can be simply extended for industrial goals.
Model free kinetics coupled with finite element method for curing simulation of thermosetting epoxy resins
Authors: Tao Qi , Pinter Gerald , Antretter Thomas , Krivec Thomas , Fuchs Peter
Published: March 2018

A finite element method algorithm for epoxy curing degree simulation was developed in Abaqus by integrating the discretized analytical solution of the model free kinetics into its user subroutines. This method was verified by nonisothermal and isothermal DSC experiments of an epoxy resin. By means of this method, the real manufacturing press cycle could be simulated regarding temperature distribution and curing degree with advanced curing degree‐dependent material properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46408.
Morphology and performance of poly(vinylidene fluoride) flat sheet membranes: Thermodynamic and kinetic aspects
Authors: Enayatzadeh Mohammad , Mohammadi Toraj
Published: March 2018

In this study, poly(vinylidene fluoride) (PVDF) membranes were prepared using two different solvents with various polymer concentrations to investigate the predominant kinetic or thermodynamic aspects of membrane preparation in a phase separation process. For this purpose, dimethyl sulfoxide (DMSO) as a weak solvent and N‐2‐methylpyrrolidone (NMP) as a strong solvent were used with polymer concentrations between 8 and 15 wt %. Scanning electron microscopy and water content, contact angle, and pore size measurements were used to assess the factors affecting the physicochemical properties of the prepared membranes. The results showed that in the case of NMP, the membrane structure is mainly controlled by thermodynamic parameters, while when using DMSO, kinetic parameters are predominant. According to the results, the prepared PVDF‐based membranes with DMSO exhibited a relatively denser top layer and less permeation compared to the NMP/PVDF membranes. The difference between the viscosities of the casting solutions with equal polymer concentrations in DMSO and NMP was considered to be the main effective factor in solvent/nonsolvent exchange, resulting in denser top layers in the DMSO/PVDF membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46419.
Electrospinning preparation of a graphene oxide nanohybrid proton‐exchange membrane for fuel cells
Authors: Zhang Shaopeng , Li Dan , Kang Jingxin , Ma Guiping , Liu Yong
Published: March 2018

Proton‐exchange membrane (PEM) is a core component of fuel cells that provides a channel for proton migration and transport. Prevailing PEMs fabricated using well‐established casting techniques have several limitations such as low proton conductivity, high fuel permeability, and poor stability. To overcome these shortcomings, this article introduces a graphene oxide (GO)‐based nanohybrid Nafion nanofiber membrane prepared using a facile electrospinning technique. On the one hand, electrospinning nanofibers provide efficient transport paths for protons, which tremendously enhance the proton conductivity. On the other hand, GO doping in PEM improves the self‐humidification, stabilities (mechanical, thermal, and chemical), and proton conductivity and reduces the fuel permeability. In this research, nanofiber membranes were obtained from Nafion solutions containing 0, 0.1, and 0.2 wt % GO via electrospinning. The morphology, structure, mechanical properties, proton conductivity, water uptake, and swelling properties of the membranes were studied. The results demonstrated that the comprehensive performance of PEM was significantly improved. The new findings may promote the wide application of PEM fuel cells. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2018,135, 46443.
Influence of the morphological structure of carbon nanotubes on the viscoelasticity of PMMA‐based nanocomposites
Authors: Lin Xiang , Li Ke , Gough Timothy , Coates Phil , Wang Dongrui , Zhang Liang
Published: March 2018

The rheological behavior of polymeric nanocomposites provides major determination for their processability. In this work, three carbon nanotubes (CNTs) with varied geometries were adopted as nanofiller and then were introduced into poly(methyl methacrylate) (PMMA) matrix with different loadings (0.07–1.0 wt %). The different preparation routine led to varied CNTs dispersion states, on which the shear viscosity and the compressibility of their melts were proved to be sensitive. The technology for the preparation of their nanocomposites played a crucial role in controlling their rheological behavior. With melting blended bare CNTs, the dynamic shear viscosity of PMMA/CNTs increased with the increase of CNTs content, accompanied by aggregated CNTs in which no polymer matrix was entrapped. With the help of surface modification and pre‐mixing, well dispersed CNTs were obtained and a rather low aggregation rate ca. 0.029% was revealed. The well dispersed CNTs with an organic layer which was constructed by small molecules and presented lower viscosity. Such CNTs led to no remarkable clusters within polymer host and played the role of lubricant with an increased‐mobility layer, which can be reflected from the weighted relaxation time spectra. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46444.
Synthesis and characterization of paraffin/TiO2‐P(MMA‐co‐BA) phase change material microcapsules for thermal energy storage
Authors: Qiu Xiao Zhong , Tao Yuan , Xu Xue Qing , He Xin Hua , Fu Xiao Yi
Published: March 2018

Microcapsules based on a phase changing paraffin core and modified titanium dioxide–poly(methyl methacrylate‐co‐butyl acrylate) [P(MMA‐co‐BA)] hybrid shell were prepared via a Pickering emulsion method in this study. The microcapsules exhibit an irregularly spherical morphology with the size range of 3–24 µm. The addition of BA can enhance the toughness of the brittle polymer poly(methyl methacrylate) and improve the thermal reliability of the phase change microcapsules. The ratio of BA/MMA is in the range of 0.09–0.14, and the ratio of the monomer/paraffin is varied from 0.45 to 0.60. These microcapsules exhibit a well‐defined morphology and good thermal stability. The actual core content of the microcapsules reaches 36.09%, with an encapsulation efficiency of 73.07%. Furthermore, the prepared microcapsules present the high thermal reliability for latent‐heat storage and release after 2000 thermal cycles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46447.
Effect of modified phenolic resin on crosslinked network and performances of polyvinyl acetate blending emulsion
Authors: Mao Jian , Zhuang Qixin , Peng Sai , Liu Qiang , Qian Jun
Published: March 2018

The water‐soluble phenolic resin (PF) and the poly(vinyl alcohol) (PVA) modified phenolic resin (PPF) were synthesized by alkali catalysis method. Both were used as curing agents to blend with the polyvinyl acetate (PVAc) emulsion. The obtained PF, PPF and blending emulsion were characterized by FT‐IR, DSC, DLS, TEM, and viscosity analysis. The thermal stability of latex films was enhanced after blending. When the PF and PPF content was up to 15 wt %, the peel strength of the blending emulsion increased from 17.89 N/25 mm to 21.32 N/25 mm and 23.37 N/25 mm and the shear impact strength were 1.4 and 1.6 times that of unmodified emulsion adhesive, respectively. Moreover, the modification effect of PPF was better than PF due to its tough crosslinked network. Finally, layer cohesion played an increasingly important role in bonding forces with the increment of the PPF content by the glue residue analysis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46448.
Synergistic effect of α‐ZrP and graphene oxide nanofillers on the gas barrier properties of PVA films
Authors: Ding Jie , Zhao Chunxia , Zhao Ling , Li Yuntao , Xiang Dong
Published: March 2018

Two types of 2D nanofillers, α‐zirconium phosphate (α‐ZrP) and graphene oxide (GO), were synthesized and incorporated into poly(vinyl alcohol) (PVA) with 1 wt % loading level at various α‐ZrP:GO (Z:G = 5:1, 2:1, 1:1, 1:2, and 1:5) ratios. The resulting nanocomposites were tested for barrier properties by casting films from solution. The structure and morphology of α‐ZrP and GO were characterized by Fourier‐transform infrared spectroscopy, atomic force microscope, scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction, which demonstrated successful preparation of exfoliated α‐ZrP and GO. The physical characteristics of the nanocomposite films, including thermal, mechanical, and gas barrier properties were investigated. The results indicated that the tensile strength, Young's modulus, and elongation at break of the PVA nanocomposite films with Z:G hybrid nanofiller improved compared to neat PVA. The glass transition temperature, melting temperature, and crystallinity also increased. Consequently there appears to be a synergistic effect with these two types of nanofillers that formed a specific macro structure of a “wall.” This macrostructure resulted in excellent O2 gas barrier properties with the PVA/Z:G‐5:1 nanocomposite films having the best performance. The
of the PVA/Z:G‐5:1 nanocomposite decreased from 1.835 × 10−16 to 0.587 × 10−16 cm3 cm cm−2 s−1 Pa−1 compared with neat PVA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46455.
Facile ZIF‐8 functionalized hierarchical micronanofiber membrane for high‐efficiency separation of water‐in‐oil emulsions
Authors: Xu Si , Ren Long‐Fei , Zhou Qing , Bai Hongwei , Li Jun , Shao Jiahui
Published: March 2018

The efficient separation and recovery of oil from water‐in‐oil emulsion poses a great challenge because of the rapid development of the petrochemical industry throughout the world. In this study, a facile method to develop a ZIF‐8 functionalized hierarchical micronanofiber membrane for high‐efficiency oil/water separation was investigated. The electrospun PVDF/ZnO membrane was made, on which ZIF‐8 crystal seeds were then created with the revitalizing step and expanded in the growth step, and finally functionalized hierarchical micronanofiber PVDF‐g‐ZIF‐8 membrane was obtained. Results showed that oleophilic ZIF‐8 crystals on the surface of PVDF membrane dramatically increased the wettability of oil and tuned PVDF membrane from olephobicity to oleophilicity. The hydrophobic/lipophilic PVDF‐g‐ZIF‐8 membrane with a water contact angle up to 158° and a toluene contact angle down to 0° provides its separation efficiency for water‐in‐oil emulsion of 92.93% in an environmentally friendly and energy‐saving manner. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46462.
Trabecular Anisotropy in the Primate Mandibular Condyle Is Associated with Dietary Toughness
Authors: Coiner‐Collier Susan , Vogel Erin R. , Scott Robert S.
Published: March 2018

Past attempts to establish a relationship between mandibular morphology and different dietary categories (e.g., frugivore, folivore, insectivore) have had mixed results, possibly because descriptive dietary categories are too broad and obscure variation within primate diets. Another potential reason is that not all aspects of skeletal architecture, especially trabecular anisotropy, have factored into functional assessments of dietary inputs into jaw form. Recent emphasis on quantifying food mechanical properties (FMPs) has provided an alternative to reliance on dietary categories. We used data on FMPs to test for correlations among dietary toughness and Young's modulus and the trabecular structure of the mandibular condyle, which is loaded during feeding and should reflect differences in masticatory stresses associated with different dietary FMPs. Adult primate mandibles from 11 species were imaged using high‐resolution X‐ray computed tomography, and trabecular structure was analyzed with BoneJ and Quant3D to assess common three‐dimensional trabecular parameters. Results of phylogenetic generalized least squares analysis suggested a positive correlation between the degree of anisotropy (DA) and toughness, and weaker correlations between FMPs and various other trabecular variables. Because the DA contributes to the mechanical properties of bone, these results suggest a functional relationship between dietary toughness and trabecular anisotropy in the mandibular condyle. Such a perspective underscores the need to consider all aspects of skeletal morphology in evaluating the links between diet and jaw biomechanics. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.
Design, synthesis, and molecular modeling of heterocyclic bioisostere as potent PDE4 inhibitors
Authors: Almatary Aya M. , Elmorsy Mohammad A. , El Husseiny Walaa M. , Selim Khalid B. , El‐Sayed Magda A.‐A.
Published: March 2018

A new hybrid template was designed by combining the structural features of phosphodiesterase 4 (PDE4) inhibitors with several heterocyclic moieties which present an integral part in the skeleton of many apoptotic agents. Thirteen compounds of the synthesized hybrids displayed higher inhibitory activity against PDE4B than the reference drug, roflumilast. Further investigation indicated that compounds 13b and 20 arrested the cell cycle at the G2/M phase and the pre‐G1 phase, and induced cell death by apoptosis of A549 cells in a caspase‐dependent manner.
Geophysics and preventive archaeology: comparison with trial trenching on the CSNE project (France)
Authors: Hulin Guillaume , Bayard Didier , Depaepe Pascal , Koehler Alain , Prilaux Gilles , Talon Marc
Published: March 2018

Geophysical techniques are clearly beneficial for archaeology, but limits exist. A good knowledge of these limitations is important in order to estimate precisely the reliability of these remote sensing techniques. The Canal Seine‐Nord Europe project provides a good opportunity to compare geophysical results with those from trial trenching with a mechanical digger. In 2009, magnetic and resistivity surveys were undertaken over a surface of approximately 60 ha, independently of archaeological evaluation by trial trenching. Thirteen archaeological sites, mainly constituted in pits, post‐holes and ditches, were discovered in this area. Twelve of them were detected by trial trenching and only three by geophysical survey. This case study based on archaeological feedback shows that geophysics has to be used with caution for evaluation of this type of archaeological and pedological context (luvisols on decarbonated loess) very common for the north of France.
Multi‐Anion Intercalated Layered Double Hydroxide Nanosheet‐Assembled Hollow Nanoprisms with Improved Pseudocapacitive and Electrocatalytic Properties
Authors: Li Zhengping , Han Fangchun , Li Cheng , Jiao Xiuling , Chen Dairong
Published: March 2018

Electrochemically active hollow nanostructured materials hold great promise in diverse energy conversion and storage applications, however, intricate synthesis steps and poor control over compositions and morphologies have limited the realization of delicate hollow structures with advanced functional properties. In this study, we demonstrate a one‐step wet‐chemical strategy for co‐engineering the hollow nanostructure and anion intercalation of nickel cobalt layered double hydroxide (NiCo‐LDH) to attain highly electrochemical active energy conversion and storage functionalities. Self‐templated pseudomorphic transformation of cobalt acetate hydroxide solid nanoprisms using nickel nitrate leads to the construction of well‐defined NiCo‐LDH hollow nanoprisms (HNPs) with multi‐anion intercalation. The unique hierarchical nanosheet‐assembled hollow structure and efficiently expanded interlayer spacing offer an increased surface area and exposure of active sites, reduced mass and charge transfer resistance, and enhanced stability of the materials. This leads to a significant improvement in the pseudocapacitive and electrocatalytic properties of NiCo‐LDH HNP with respect to specific capacitance, rate and cycling performance, and OER overpotential, outperforming most of the recently reported NiCo‐based materials. This work establishes the potential of manipulating sacrificial template transformation for the design and fabrication of novel classes of functional materials with well‐defined nanostructures for electrochemical applications and beyond.
Control of the Interfacial Wettability to Synthesize Highly Dispersed PtPd Nanocrystals for Efficient Oxygen Reduction Reaction
Authors: Wei Hao , Hu Zhi‐Yi , Xiao Yu‐Xuan , Tian Ge , Ying Jie , Van Tendeloo Gustaaf , Janiak Christoph , Yang Xiao‐Yu , Su Bao‐Lian
Published: March 2018

Highly dispersed PtPd bimetallic nanocrystals with enhanced catalytic activity and stability were prepared by adjusting the interfacial wettability of the reaction solution on a commercial carbon support. This approach holds great promise for the development of high‐performance and low‐cost catalysts for practical applications.
Recent Advances in Imidazoliumyl‐Substituted Phosphorus Compounds
Authors: Schwedtmann Kai , Zanoni Giuseppe , Weigand Jan J.
Published: March 2018

This review aims to highlight the recent developments in the chemistry of selected imidazoliumyl‐substituted phosphorus compounds. The synthetic approaches for their preparation with phosphorus in various oxidation states and coordination environments are discussed. Their intriguing properties and versatile chemistry strongly depends on the bonding motif at the P atoms, which is given special focus.
Boosting ORR Catalytic Activity by Integrating Pyridine‐N Dopants, a High Degree of Graphitization, and Hierarchical Pores into a MOF‐Derived N‐Doped Carbon in a Tandem Synthesis
Authors: Liu Dandan , Li Liangjun , Xu Huanfei , Dai Pengcheng , Wang Ying , Gu Xin , Yan Liting , Zhao Guoming , Zhao Xuebo
Published: March 2018

N‐doped carbon materials represent promising metal‐free electrocatalysts for the oxygen reduction reaction (ORR), the cathode reaction in fuel cells, metal–air batteries, and so on. A challenge for optimizing the ORR catalytic activities of these electrocatalysts is to tune their local structures and chemical compositions in a rational and controlled way that can achieve the synergistic function of each factor. Herein, we report a tandem synthetic strategy that integrates multiple contributing factors into an N‐doped carbon. With an N‐containing MOF (ZIF‐8) as the precursor, carbonization at higher temperatures leads to a higher degree of graphitization. Subsequent NH3 etching of this highly graphitic carbon enabled the introduction of a higher content of pyridine‐N sites and higher porosity. By optimizing these three factors, the resultant carbon materials displayed ORR activity that was far superior to that of carbon derived from a one‐step pyrolysis. The onset potential of 0.955 V versus a reversible hydrogen electrode (RHE) and the half‐wave potential of 0.835 V versus RHE are among the top ranks of metal‐free ORR catalysts and are comparable to commercial Pt/C (20 wt %) catalysts. Kinetic studies revealed lower H2O2 yields, higher electron‐transfer numbers, and lower Tafel slopes for these carbon materials compared with that derived from a one‐step carbonization. These findings verify the effectiveness of this tandem synthetic strategy to enhance the ORR activity of N‐doped carbon materials.
Cooperative and FRET‐Assisted Brightness Enhancement in Oligo(phenylene ethynylene): Quantum Dot Organic–Inorganic Nanohybrids
Authors: Gopi Arun , Sajitha Manikantan , Haridas Reethu , Varghese Listo , Yoosaf Karuvath
Published: March 2018

Herein, we combine the ideas of concerted emission from fluorophore ensembles and its further amplification through FRET in an organic–inorganic hybrid approach. Spherical and highly fluorescent organic nanoparticles (FONPs, Φf=0.38), prepared by the self‐assembly of oligo(phenylene ethynylene) (OPE) molecules, were selected as a potential donor material. This organic core was then decorated with a shell of fluorescent CdSe/ZnS core–shell quantum dots (QDs; ≅5.5 nm, Φf=0.27) with the aid of a bifunctional ligand, mercaptopropionic acid. Its high extinction coefficient (ϵ≈4.1×105 m−1 cm−1) and good spectral match with the emission of the FONPs (J(λ)≈4.08×1016 m−1 cm−1 nm4) made them a better acceptor candidate to constitute an efficient FRET pair (ΦFRET=0.8). As a result, the QD fluorescence intensity was enhanced by more than twofold. The fundamental calculations carried out indicated an improvement in all the FRET parameters as the number of QDs around the FONPs was increased. This, together with the localization of multiple QDs in a nanometric dimension (volume≈1.8×106 nm3), gave highly bright reddish luminescent hybrid particles as visualized under a fluorescence microscope.
Modeling autism in non‐human primates: Opportunities and challenges
Authors: Zhao Hui , Jiang Yong‐Hui , Zhang Yong Q.
Published: March 2018

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication deficits and restricted, repetitive patterns of behavior. For more than a decade, genetically‐modified, risk factor‐induced, as well as naturally occurring rodent models for ASD have been used as the most predominant tools to dissect the molecular and circuitry mechanisms underlying ASD. However, the apparent evolutionary differences in terms of social behavior and brain anatomy between rodents and humans have become an issue of debate regarding the translational value of rodent models for studying ASD. More recently, genome manipulation of non human primates using lentivirus‐based gene expression, TALEN and CRISPR/Cas9 mediated gene editing techniques, has been reported. Genetically modified non‐human primate models for ASD have been produced and characterized. While the feasibility, value, and exciting opportunities provided by the non‐human primate models have been clearly demonstrated, many challenges still remain. Here, we review current progress, discuss the remaining challenges, and highlight the key issues in the development of non‐human primate models for ASD research and drug development. Autism Res 2018, 11: 686–694. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

Lay Summary

Over the last two decades, genetically modified rat and mouse models have been used as the most predominant tools to study mechanisms underlying autism spectrum disorder (ASD). However, the apparent evolutionary differences between rodents and humans limit the translational value of rodent models for studying ASD. Recently, several non‐human primate models for ASD have been established and characterized. Here, we review current progress, discuss the challenges, and highlight the key issues in the development of non‐human primate models for ASD research and drug development.
Structural basis of noncanonical polyphenol oxidase activity in DLL‐II: A lectin from Dolichos lablab
Authors: L. Vishweshwaraiah Yashavanth , Acharya Abhishek , Prakash Balaji
Published: March 2018

Lectins known to possess an additional enzymatic function are called leczymes. Previous studies reported a unique polyphenol oxidase (PPO) activity in DLL‐II—a leczyme from Dolichos lablab. DLL‐II shares a high sequence and structural homology with DBL—another leczyme from Dolichos biflorus. Incidentally, DBL possesses lipoxygenase activity, but not the PPO activity. Legume lectins usually possess two metal‐binding sites A and B. Although these sites are conserved in both DBL and DLL‐II, site A in DLL‐II is occupied by Mn2+ and site B by Ca2+. In contrast, DLL‐II binds Cu2+ and Ca2+ at sites A and B, respectively. Here, investigating the structural basis of PPO activity in DLL‐II, we find that the PPO activity is only dependent on Cu2+, but not Ca2+; and the lectin activity requires only Ca2+. Further, our analysis suggests that an alternative mechanism of PPO reaction may be operative in DLL‐II, which involves a mononuclear Cu2+ metal center; this is in contrast to the bi‐nuclear Cu2+ metal center commonly observed in all PPOs. Importantly, structural and computational approaches employed here, we hypothesize possible PPO binding sites and the corresponding migration channels for accessing the active site.
Relative efficiency of unequal versus equal cluster sizes in cluster randomized trials using generalized estimating equation models
Authors: Liu Jingxia , Colditz Graham A.
Published: March 2018

There is growing interest in conducting cluster randomized trials (CRTs). For simplicity in sample size calculation, the cluster sizes are assumed to be identical across all clusters. However, equal cluster sizes are not guaranteed in practice. Therefore, the relative efficiency (RE) of unequal versus equal cluster sizes has been investigated when testing the treatment effect. One of the most important approaches to analyze a set of correlated data is the generalized estimating equation (GEE) proposed by Liang and Zeger, in which the “working correlation structure” is introduced and the association pattern depends on a vector of association parameters denoted by ρ. In this paper, we utilize GEE models to test the treatment effect in a two‐group comparison for continuous, binary, or count data in CRTs. The variances of the estimator of the treatment effect are derived for the different types of outcome. RE is defined as the ratio of variance of the estimator of the treatment effect for equal to unequal cluster sizes. We discuss a commonly used structure in CRTs—exchangeable, and derive the simpler formula of RE with continuous, binary, and count outcomes. Finally, REs are investigated for several scenarios of cluster size distributions through simulation studies. We propose an adjusted sample size due to efficiency loss. Additionally, we also propose an optimal sample size estimation based on the GEE models under a fixed budget for known and unknown association parameter (ρ) in the working correlation structure within the cluster.
RoMo: An efficient strategy for functional mosaic analysis via stochastic Cre recombination and gene targeting in the ROSA26 locus
Authors: Movahedi Kiavash , Wiegmann Robert , De Vlaminck Karen , Van Ginderachter Jo A. , Nikolaev Viacheslav O.
Published: March 2018

Functional mosaic analysis allows for the direct comparison of mutant cells with differentially marked control cells in the same organism. While this offers a powerful approach for elucidating the role of specific genes or signalling pathways in cell populations of interest, genetic strategies for generating functional mosaicism remain challenging. We describe a novel and streamlined approach for functional mosaic analysis, which combines stochastic Cre/lox recombination with gene targeting in the ROSA26 locus. With the RoMo strategy a cell population of interest is randomly split into a cyan fluorescent and red fluorescent subset, of which the latter overexpresses a chosen transgene. To integrate this approach into high‐throughput gene targeting initiatives, we developed a procedure that utilizes Gateway cloning for the generation of new targeting vectors. RoMo can be used for gain‐of‐function experiments or for altering signaling pathways in a mosaic fashion. To demonstrate this, we developed RoMo‐dnGs mice, in which Cre‐recombined red fluorescent cells co‐express a dominant‐negative Gs protein. RoMo‐dnGs mice allowed us to inhibit G protein‐coupled receptor activation in a fraction of cells, which could then be directly compared to differentially marked control cells in the same animal. We demonstrate how RoMo‐dnGs mice can be used to obtain mosaicism in the brain and in peripheral organs for various cell types. RoMo offers an efficient new approach for functional mosaic analysis that extends the current toolbox and may reveal important new insights into in vivo gene function.
Characterization of a membrane‐separated and a membrane‐less electrobioreactor for bioelectrochemical syntheses
Authors: Krieg Thomas , Phan Linh M. P. , Wood Jeffery A. , Sydow Anne , Vassilev Igor , Krömer Jens O. , Mangold Klaus‐Michael , Holtmann Dirk
Published: March 2018

Bioelectrochemical systems (BESs) have the potential to contribute to the energy revolution driven by the new bio‐economy. Until recently, simple reactor designs with minimal process analytics have been used. In recent years, assemblies to host electrodes in bioreactors have been developed resulting in so‐called “electrobioreactors.” Bioreactors are scalable, well‐mixed, controlled, and therefore widely used in biotechnology and adding an electrode extends the possibilities to investigate bioelectrochemical production processes in a standard system. In this work, two assemblies enabling a separated and non‐separated electrochemical operation, respectively, are designed and extensively characterized. Electrochemical losses over the electrolyte and the membrane were comparable to H‐cells, the bioelectrochemical standard reaction system. An effect of the electrochemical measurements on pH measurements was observed if the potential is outside the range of −1,000 to +600 mV versus Ag/AgCl. Electrobiotechnological characterization of the two assemblies was done using Shewanella oneidensis as an electroactive model organism. Current production over time was improved by a separation of anodic and cathodic chamber by a Nafion® membrane. The developed electrobioreactor was used for a scale‐up of the anaerobic bioelectrochemical production of organic acids and lysine from glucose using an engineered Corynebacterium glutamicum. Comparison to a small‐scale custom‐made electrobioreactor indicates that anodic electro‐fermentation of lysine and organic acids might not be limited by the BES setup but by the biocatalysis of the cells.
Hollow microcarriers for large‐scale expansion of anchorage‐dependent cells in a stirred bioreactor
Authors: YekrangSafakar Ashkan , Acun Aylin , Choi Jin‐Woo , Song Edward , Zorlutuna Pinar , Park Kidong
Published: March 2018

With recent advances in biotechnology, mammalian cells are used in biopharmaceutical industries to produce valuable protein therapeutics and investigated as effective therapeutic agents to permanently degenerative diseases in cell based therapy. In these exciting and actively expanding fields, a reliable, efficient, and affordable platform to culture mammalian cells on a large scale is one of the most vital necessities. To produce and maintain a very large population of anchorage‐dependent cells, a microcarrier‐based stirred tank bioreactor is commonly used. In this approach, the cells are exposed to harmful hydrodynamic shear stress in the bioreactor and the mass transfer rates of nutrients and gases in the bioreactor are often kept below an optimal level to prevent cellular damages from the shear stress. In this paper, a hollow microcarrier (HMC) is presented as a novel solution to protect cells from shear stress in stirred bioreactors, while ensuring sufficient and uniform mass transfer rate of gases and nutrients. HMC is a hollow microsphere and cells are cultured on its inner surface to be protected, while openings on the HMC provide sufficient exchange of media inside the HMC. As a proof of concept, we demonstrated the expansion of fibroblasts, NIH/3T3 and the expansion and cardiac differentiation of human induced pluripotent stem cells, along with detailed numerical analysis. We believe that the developed HMC can be a practical solution to enable large‐scale expansion of shear‐sensitive anchorage‐dependent cells in an industrial scale with stirred bioreactors.