bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper and Silver Carbene Complexes without Heteroatom‐Stabilization: Structure, Spectroscopy, and Relativistic Effects
Authors: Hussong Matthias W. , Hoffmeister Wilhelm T. , Rominger Frank , Straub Bernd F. 
Published: July 2015

AbstractSalts of a copper and a silver carbene complex were prepared from dimesityl diazomethane, made possible by the steric shielding of the N‐heterocyclic carbene (NHC) ancillary ligand IPr**. The mint‐green complex [IPr**Ag=CMes2]+[NTf2]− is the first isolated silver carbene complex without heteroatom donor substituents. Single‐crystal X‐ray diffraction provides evidence for a predominant carbenoid character, and supports the postulation of such reactive species as intermediates in silver‐catalyzed CH activation reactions. The greenish yellow copper carbene complex [IPr**Cu=CMes2]+[NTf2]− has spectroscopic properties in between the isostructural silver complex and the already reported emerald green gold carbene complex. A comparison in the Group 11 series indicates that relativistic effects are responsible for the strong σ bond and the significant π back‐bonding in the gold carbene moiety.
High‐Throughput, Label‐Free Isolation of Cancer Stem Cells on the Basis of Cell Adhesion Capacity
Authors: Zhang Yuanqing , Wu Minhao , Han Xin , Wang Ping , Qin Lidong 
Published: July 2015

AbstractHerein we report a microfluidics method that enriches cancer stem cells (CSCs) or tumor‐initiating cells on the basis of cell adhesion properties. In our on‐chip enrichment system, cancer cells were driven by hydrodynamic forces to flow through microchannels coated with basement membrane extract. Highly adhesive cells were captured by the functionalized microchannels, and less adhesive cells were collected from the outlets. Two heterogeneous breast cancer cell lines (SUM‐149 and SUM‐159) were successfully separated into enriched subpopulations according to their adhesive capacity, and the enrichment of the cancer stem cells was confirmed by flow cytometry biomarker analysis and tumor‐formation assays. Our findings show that the less adhesive phenotype is associated with a higher percentage of CSCs, higher cancer‐cell motility, and higher resistance to chemotherapeutic drugs.
Fabrication of amido group functionalized carbon quantum dots and its transparent luminescent epoxy matrix composites
Authors: Chen Lanlan , Zhang Chen , Du Zhongjie , Li Hangquan , Zhang Li , Zou Wei 
Published: July 2015

ABSTRACTFunctional amido groups are modified onto the surface of carbon quantum dots (CQDs) in order to provide reactive groups. The modified CQDs are subsequently added into amine cured epoxy resin system. After curing reaction, transparent and luminescent composites are obtained. The modified CQDs are denoted as CQDs@NH2, and composites studied in this article are denoted as CQDs@NH2/epoxy. It is found that the dispersion of CQDs@NH2 in epoxy matrix is effectively improved with the bridge of covalent bonding interface. As a result, the homogenously dispersed CQDs@NH2 reduce light scattering. And more than double increased transparency and eightfold enhanced luminescence of CQDs@NH2/epoxy are obtained compared with original CQDs@COONa/epoxy composites. This composite has potential for encapsulating materials in white light‐emitting diodes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42667.
Stabilization and Control of Delayed Recycling High Order Systems with one Unstable Pole at the Direct Path
Authors: Marquez‐Rubio Juan Francisco , Vazquez‐Guerra Rocio Jasmin , Muro‐Cuéllar Basilio del , Sename Olivier 
Published: July 2015

AbstractIn this work the stabilization and control of delayed recycling systems is addressed. Recycling systems are characterized by possessing two main paths, named the direct (feedforward) and the recycling (feedback) paths. Such class of systems reuse the energy and/or the partially processed matter increasing the efficiency of the overall process. A control methodology is proposed for the stabilization and control of this kind of system. The particular class of systems addressed here contains one unstable pole, m stable poles, a delay term and possible p left half plane (LHP) zeros in the direct path and a delayed stable subsystem in the recycling path. The strategy is based on an asymptotic observer‐predictor to estimate the required internal signals. Necessary and sufficient conditions are stated in order to guarantee the stabilization of the proposed scheme, achieving step tracking and rejection.
Importance of the Support Properties for Immobilization or Purification of Enzymes
Authors: Santos Jose Cleiton S. dos , Barbosa Oveimar , Ortiz Claudia , Berenguer‐Murcia Angel , Rodrigues Rafael C. , Fernandez‐Lafuente Roberto 
Published: July 2015

AbstractImmobilization and purification of enzymes are usual requirements for their industrial use. Both purification and immobilization have a common factor: they use a solid activated support. Using a support for enzyme purification means having mild conditions for enzyme release and a selective enzyme–support interaction is interesting. When using a support for immobilization, however, enzyme desorption is a problem. The improvement of enzyme features through immobilization is a usual objective (e.g., stability, selectivity). Thus, a support designed for enzyme purification and a support designed for enzyme immobilization may differ significantly. In this review, we will focus our attention on the requirements of a support surface to produce the desired objectives. The ideal physical properties of the matrix, the properties of the introduced reactive groups, the best surface activation degree to reach the desired objective, and the properties of the reactive groups will be discussed.
Source of Selectivity in Oxidative Cross‐Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3‐Hexafluoropropan‐2‐ol
Authors: Elsler Bernd , Wiebe Anton , Schollmeyer Dieter , Dyballa Katrin M. , Franke Robert , Waldvogel Siegfried R. 
Published: July 2015

AbstractSolvents such as 1,1,1,3,3,3‐hexafluoroisopropanol (HFIP) with a high capacity for donating hydrogen bonds generate solvates that enter into selective cross‐coupling reactions of aryls upon oxidation. When electric current is employed for oxidation, reagent effects can be excluded and a decoupling of nucleophilicity from oxidation potential can be achieved. The addition of water or methanol to the electrolyte allows a shift of oxidation potentials in a specific range, creating suitable systems for selective anodic cross‐coupling reactions. The shift in the redox potentials depends on the substitution pattern of the substrate employed. The concept has been expanded from arene–phenol to phenol–phenol as well as phenol–aniline cross‐coupling. This driving force for selectivity in oxidative coupling might also explain previous findings using HFIP and hypervalent iodine reagents.
Highly Diastereo‐ and Enantioselective Michael Addition of Nitroalkanes to 2‐Enoyl‐Pyridine N‐Oxides Catalyzed by Scandium(III)/Copper(II) Complexes
Authors: Li Lijun , Zhang Sheng , Hu Yanbin , Li Yanan , Li Chong , Zha Zhenggen , Wang Zhiyong 
Published: July 2015

AbstractA C2‐symmetric Schiff‐base ligand, derived from tridentate‐Schiff‐base, was developed and successfully applied to the asymmetric Michael addition of nitroalkanes to 2‐enoyl‐pyridine N‐oxides. With this newly catalytic system, an unprecedented diastereoselectivity was obtained in the asymmetric Michael addition of nitroalkanes to 2‐enoyl‐pyridine N‐oxides. In addition, a switch in enantioselectivity was achieved by using this newly catalytic system and our previous catalyst. After a facile reduction, the optically active adduct was converted to a biologically active dihydro‐2H‐pyrrol 4 a. Furthermore, a connection of two tridentate‐Schiff‐base subunits proved to be an effective strategy in ligand design.
Charge‐Transfer‐Assisted Supramolecular 1 D Nanofibers through a Cholesteric Structure‐Directing Agent: Self‐Assembly Design for Supramolecular Optoelectronic Materials
Authors: Babu Thunga Madhu , Prasad Edamana 
Published: July 2015

AbstractSelf‐assembly of pyrene butyric acid (PBA) and 2,4,7‐trinitro‐9H‐fluoren‐9‐one (TNF) directed by a pyridine‐linked cholesterol unit resulted in the formation of a conducting material (1.9472×10−4 S Cm−1) due to the formation of 1 D nanofibers. X‐ray diffraction, IR, and atomic force microscopic (AFM) techniques were used to establish the mechanism of the self‐assembly of the multicomponent gels. Results indicate efficient charge transfer in the 1 D nanofibers, assisted by hydrogen bonding.
Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide by Using Bifunctional One‐Component Phosphorus‐Based Organocatalysts
Authors: Büttner Hendrik , Steinbauer Johannes , Werner Thomas 
Published: July 2015

AbstractNumerous bifunctional organocatalysts were synthesized and tested for the atom‐efficient addition of carbon dioxide and epoxides to produce cyclic carbonates. These catalysts are based on phosphonium salts containing an alcohol moiety in the side chain for substrate activation through hydrogen bonding. In the model reaction, converting 1,2‐butylene oxide with CO2, 19 catalysts were tested to determine structure–activity relationships. In total, 28 epoxides were converted with CO2 to give the respective cyclic carbonates in yields of up to 99 %. Even at 45 °C, the most active catalyst was able to produce cyclic carbonates selectively in high yields. The carbonates were generally obtained as analytically pure products after simple filtration over silica gel. This single‐component catalyst system works under neat and mild reaction conditions and tolerates several useful moieties.
Security protocols in body sensor networks using visible light communications
Authors: Huang Xin , Gao Xiong , Yan Zheng 
Published: July 2015

SummaryThe fifth generation (5G) wireless system aims to support body sensor networks (BSNs) by increasing the interconnectivity of electronic devices. BSNs in the 5G era will enable many interesting applications, for example, medical services. In these applications, sensor networks collect sensitive information of individual human beings. Thus, security becomes significantly important in BSNs. However, many key distribution protocols are based on pre‐deployed secrets. There are some problems: It is difficult to update pre‐deployed secrets after they are compromised, or users want to re‐deploy a device node. In this paper, we propose several security protocols including two key establishment protocols for BSNs by using visible light communications (VLCs). These protocols have a number of advantages. First, they can be widely applied in current BSNs without extra conditions because VLCs can be supported in most BSNs. Second, these protocols do not need pre‐shared secrets; thus, it is not necessary for users to change pre‐shared secrets if they are compromised. Experiments and analysis further show that (1) VLCs based on on–off keying are preferred; (2) computation and communication burden of these protocols are acceptable; and (3) these protocols bring little burden on users. Copyright © 2015 John Wiley & Sons, Ltd.
Dynamics of novel forests of Castilla elastica in Puerto Rico: from species to ecosystems
Authors: Fonseca da Silva Jéssica 
Published: July 2015

AbstractNovel forests (NFs)—forests that contain a combination of introduced and native species—are a consequence of intense anthropogenic disturbances and the natural resilience of disturbed ecosystems. The extent to which NFs have similar forest function as comparable native secondary forests is a matter of debate in the scientific community. Little is known about the performance of individual species in those forests. This study focuses on the functional attributes of Castilla elastica NFs in Puerto Rico and on the differences between introduced and native species growing side by side in these forests. Rates of processes measured here were later compared with data from literature about NSFs. I hypothesize that juvenile plants of C. elastica in NFs have higher survival rate than those of native species and that C. elastica trees have faster biomass fluxes than native trees. To test the hypotheses, I measured survival rates of juvenile plants and tree growth and characterized the aboveground litter fluxes and storage. Although juvenile plants of native species displayed higher survival rates than those of C. elastica (53% vs. 28%), the latter was dominant in the understory (96%). Stand biomass growth rate was 2.0 ± 0.4 (average ± one standard deviation) Mg·ha−1·year−1 for the whole forest, and Guarea guidonia, a native species, exhibited the highest tree growth. Total litter fall was 9.6 ± 0.5 Mg·ha−1·year−1, and mean litter standing stock was 4.4 ± 0.1 Mg·ha−1. Castilla elastica litter fall decomposed twice as fast as that of native species (5.8 ± 1.1 vs. 3.03 ± 1 k·year−1). Literature comparisons show that the present NFs differ in some rates of processes from NSFs. This study brings unique and detailed supporting data about the ecological dynamics under mature novel forest stands. Further comprehensive studies about NFs are important to strengthen the body of knowledge about the wide range of variation of emerging tropical ecosystems. Due to the large increase in the area covered by NFs, greater attention is needed to understand their functioning, delivery of ecological services and management requirements.
Widespread positive but weak assortative mating by diet within stickleback populations
Authors: Ingram Travis , Jiang Yuexin , Rangel Racine , Bolnick Daniel I. 
Published: July 2015

AbstractAssortative mating – correlation between male and female traits – is common within populations and has the potential to promote genetic diversity and in some cases speciation. Despite its importance, few studies have sought to explain variation in the extent of assortativeness across populations. Here, we measure assortative mating based on an ecologically important trait, diet as inferred from stable isotopes, in 16 unmanipulated lake populations of three‐spine stickleback. As predicted, we find a tendency toward positive assortment on the littoral–pelagic axis, although the magnitude is consistently weak. These populations vary relatively little in the strength of assortativeness, and what variation occurs is not explained by hypothesized drivers including habitat cosegregation, the potential for disruptive selection, costs to choosiness, and the strength of the relationship between diet and body size. Our results support recent findings that most assortative mating is positive, while suggesting that new approaches may be required to identify the environmental variables that drive the evolution of nonrandom mating within populations.
An Efficient Approach to Octabromophenylethyl‐Functionalized Cage Silsesquioxane and Its Use in Constructing Hybrid Porous Materials
Authors: Jiang Chundong , Yang Wenyan , Li Liguo , Hou Yuqi , Zhao Xiaoling , Liu Hongzhi 
Published: July 2015

AbstractOctabromophenylethyl‐functionalized silsesquioxane (BrPh‐SQ) was synthesized by the Friedel–Crafts alkylation of octavinylsilsesquioxane (OVS) with bromobenzene, which acted as both the solvent and reactant and, furthermore, could be recycled after the reaction. The approach possesses the advantages of being mild, economic, and highly efficient. Further, BrPh‐SQ was used as a building block in Heck reactions with OVS and tetrakis(4‐vinylphenyl)silane to form two hybrid network polymers, that is, cage polymers 1 and 2, respectively. Cage polymer 1 showed moderate porosity with a Brunauer–Emmett–Teller specific surface area of 334 m2 g–1 and a total pore volume of 0.208 cm3 g–1. For gas‐sorption applications, the CO2 uptake of cage polymer 1 was 2.44 wt.‐% (0.55 mmol g–1) at 273 K and 101 kPa.
The Reaction of Terminal Phosphinidene Complexes [RP–W(CO)5] with Vinylbor­onic Acids: Cycloaddition vs. P–C Bond Formation
Authors: Ng Yong Xiang , Mathey François 
Published: July 2015

AbstractThe reaction of terminal phosphinidene complexes [RP–W(CO)5] with vinylboronic acids is very sensitive to the presence or absence of solid K3PO4 in suspension in the reaction medium. The products are phosphirane complexes without the salt and secondary vinylphosphine complexes in the presence of the salt. This shift of the reaction pathway is explained by the formation of vinyborates in the presence of potassium phosphate.
Inhomogeneous consistency of crystallized fat
Authors: Gregersen Sandra B. , Miller Rasmus L. , Andersen Morten D. , Hammershøj Marianne , Wiking Lars 
Published: July 2015

In this study, the degree of inhomogeneity in crystallized fat samples was evaluated in terms of texture, solid fat content, microstructure, and triacylglycerol (TAG) composition. Four different cocoa butter alternatives based on symmetric or asymmetric monounsaturated TAGs and with different contents of palmitic acid (a POP‐rich fat and a PPO‐rich fat) and steric acid (a SOS‐rich fat and a PSO‐rich fat) were studied. Significant differences (P < 0.001) in hardness between top and bottom was observed for all fats except the PSO‐rich fat. The inhomogeneous consistency was shown to be a consequence of microstructural variation within the crystallized fats. No differences in solid to liquid ratio, melting points, or polymorphic behavior between top and bottom of fats were found. Sedimentation during the crystallization process could explain the observed inhomogeneity. Although sedimentation most likely is limited to the early stages of the crystallization process due to network formation, sedimented crystals influence the crystallization kinetics and thus introduce microstructural variations. This hypothesis is supported by findings of a higher amount of trisaturated TAGs in the bottom compared with the top of crystallized fats. The PSO‐rich fat crystallizes fast compared with the other evaluated fats, which explains the more homogeneous texture of the PSO‐rich fat compared with the other evaluated fats.Practical applications: Fat crystallization plays an important role for the texture of many food products such as chocolates, confectioneries, margarine, and butter. Correct analysis of texture is thus critical when evaluating fats for the food industry. This study emphasizes that inhomogeneity in the consistency could be of practical importance for evaluation of the mechanical and textural properties of crystallized fats for instance by compression tests or small deformation rheological testing of fat samples prepared in molds or with needle penetration tests, which only include the top of a fat sample.This study shows an inhomogeneous consistency of crystallized fat samples due to microstructural variation within the fat.
Effect of ripening stage on aliphatic alcohol, 4‐monomethylsterol and 4,4‐dimethylsterol compositions of Pistacia lentiscus fruit (lentisc)
Authors: Trabelsi Hajer , Renaud Justin , Bouali Intidhar , Mayer Paul , Boukhchina Sadok 
Published: July 2015

Fruits were collected from Pistacia lentiscus trees at five distinct stages of development, and lipid extract composition of 4‐monomethylsterols, 4,4‐dimethylsterols, and aliphatic alcohol was identified and quantified using GC‐MS. Four triterpene alcohols and two 4‐methylsterols were identified by GC‐MS during the ripening of the lentisc fruit. Cycloartenol is the major component of the 4,4‐dimethylsterol fraction with up to 1093 mg/100 g of oil in the 25th DAF. The accumulation of monomethylsterols begins at 60th DAF and peaked in the 75th DAF. Furthermore, thirteen aliphatic compounds including seven belonging to the policosanol group have been identified and quantified in Pistacia lentiscus oil. During the early stages of lentisc fruit ripening, the aliphatic alcohol fraction contains predominantly policosanol molecules which are highly prized by the food and pharmaceutical industries for their therapeutic and nutritional value.Practical applications: One of the main objectives of industry is to identify plant matrices rich in molecules with good nutritional value such as 4‐monomethylsterols and 4,4‐dimethylsterols. This study allowed identification and monitoring of the dynamics of accumulation of the lentisc unsaponifiable fraction (4‐monomethylsterols, 4,4‐dimethylsterols, and aliphatic alcohols), which should contribute to determination of the maturation stages corresponding to the threshold accumulation of certain molecules with good nutritional value.Evolution of 4‐monomethylsterol, 4,4‐dimethylsterol, and aliphatic alcohol composition during maturation of Tunisian Pistacia lentiscus fruit was determined using GC‐MS methods.
Experimental and modelling studies on continuous synthesis and refining of biodiesel in a dedicated bench scale unit using centrifugal contactor separator technology
Authors: Abduh Muhammad Yusuf , Martínez Alberto Fernández , Kloekhorst Arjan , Manurung Robert , Heeres Hero J. 
Published: July 2015

Continuous synthesis and refining of biodiesel (FAME) using a laboratory scale bench scale unit was explored. The unit consists of three major parts: (i) a continuous centrifugal contactor separator (CCCS) to perform the reaction between sunflower oil and methanol; (ii) a washing unit for the crude FAME with water/acetic acid consisting of a mixer and a liquid–liquid separator; and (iii) a FAME drying unit with air. The continuous setup was successfully used for a 4 h runtime without any operational issues. The CCCS was operated at an oil flow rate of 32 mL/min, rotational speed of 35 Hz, 60°C, a catalyst concentration of 1.2% w/w and a methanol flow rate of 10 mL/min. The flow rate of water (containing 1% w/w acetic acid) for the biodiesel washing unit was 10 mL/min (20°C); the air flow rate (5% humidity) was set at 12 L/min. After 4 h runtime, approximately 7 kg of refined FAME was produced from a cumulative sunflower oil feed of 7.07 kg. The ester content of the refined FAME was 98% w/w (GC). Other relevant product properties were also determined and most were shown to meet the ASTM specifications. The refining section was modelled and optimised using ASPEN software.Practical applications: Synthesis and refining of sunflower biodiesel was successfully performed in a dedicated bench scale unit using centrifugal contactor separator technology. Besides for large scale biodiesel production, this technology has particularly potential to be applied in small mobile biodiesel units due to the compact size, robustness, flexibility in operation and high volumetric productivity of the CCCS devices.Schematic representation of the continuous bench scale unit.
Lithium‐Rich Nanoscale Li1.2Mn0.54Ni0.13Co0.13O2 Cathode Material Prepared by Co‐Precipitation Combined Freeze Drying (CP–FD) for Lithium‐Ion Batteries
Authors: Bai Ying , Li Yu , Wu Chuan , Lu Jun , Li Hui , Liu Zhaolin , Zhong Yunxia , Chen Shi , Zhang Cunzhong , Amine Khalil , Wu Feng 
Published: July 2015

AbstractNanoscale Li‐rich Li1.2Mn0.54Ni0.13Co0.13O2 material is synthesized by a co‐precipitation combined freeze drying (CP–FD) method, and compared with a conventional co‐precipitation method combined vacuum drying (CP–VD). With the combination of X‐ray diffraction (XRD) and scanning electron microscopy (SEM), it is found that the sample from CP–FD method consists of a pure phase with good crystallinity and small, homogenous particles (100‐300 nm) with uniform particle size distribution. Inductively coupled plasma spectroscopy (ICP) shows that the sample has a stoichiometric ratio of n(Li):n(Mn):n(Ni):n(Co)=9:4:1:1; and its Brunauer–Emmett–Teller (BET) specific surface area is 5.749 m2 g−1. This sample achieves excellent electrochemical properties: its initial discharge capacities are 298.9 mAh g−1 at 0.1C (20 mA g−1), 246.1 mAh g−1 at 0.5C, 215.8 mAh g−1 at 1C, and 154.2 mAh g−1 at 5C (5C charge and 5C discharge), as well as good cycling performance. In addition, the Li+ chemical diffusion coefficient of Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by the CP–FD method is 4.59×10−11 cm2 s−1, which is higher than that of the Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by CP–VD. This phenomenon illustrates the potential for Li1.2Mn0.54Ni0.13Co0.13O2 with good rate performance synthesized by CP–FD method.