bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in atmospheric composition during the 2014 APEC conference in Beijing
Authors: Wang Zhanshan , Li Yunting , Chen Tian , Li Lingjun , Liu Baoxian , Zhang Dawei , Sun Feng , Wei Qiang , Jiang Lei , Pan Libo
Published: November 2015

Five sites were selected to investigate the impact of regional‐scale air pollutant control strategies during the Asia‐Pacific Economic Cooperation (APEC) conference (1–12 November 2014) in and around Beijing. Concentrations of most of the air pollutants in the APEC period were significantly lower than those in the adjacent time period, especially when the enhanced reduction measures were implemented. Compared with the same time period in the previous 5 years (PM2.5 was compared with the last year), average concentrations of SO2, NO2, PM10, and PM2.5 in the five sites during the APEC period decreased by 62%, 41%, 36%, and 47% respectively, whereas average concentration of O3 increased by 102%. A possible cause of the increase of O3 concentrations is the stricter reduction measure on NOx compared to that applied to volatile organic compounds. Compared with the non‐APEC period in autumn 2014, concentrations of most of the chemical compositions of PM2.5 decreased significantly in the APEC period, especially SO42−, NO3−, and NH4+ (sulfate, nitrate, and ammonium). The aerosol optical depth and the columnar NO2 in the area of 39.5°–40.5°N, 116°–117°E showed a changing pattern similar to the typical gas pattern. The net effectiveness of the emission reduction measures was calculated through a comparison of concentrations of air pollutants under similar meteorological conditions. Through the reduction measures imposed during the APEC period, concentrations of CO, SO2, NO, NO2, PM10, and PM2.5 decreased by 54%, 74%, 64%, 48%, 67%, and 65%, respectively, whereas concentrations of O3 increased by 189%.
Seasonality and interannual variability of CH4 fluxes from the eastern Amazon Basin inferred from atmospheric mole fraction profiles
Authors: Basso Luana S. , Gatti Luciana V. , Gloor Manuel , Miller John B. , Domingues Lucas G. , Correia Caio S. C. , Borges Viviane F.
Published: November 2015

The Amazon Basin is an important region for global CH4 emissions. It hosts the largest area of humid tropical forests, and around 20% of this area is seasonally flooded. In a warming climate it is possible that CH4 emissions from the Amazon will increase both as a result of increased temperatures and precipitation. To examine if there are indications of first signs of such changes we present here a 13 year (2000–2013) record of regularly measured vertical CH4 mole fraction profiles above the eastern Brazilian Amazon, sensitive to fluxes from the region upwind of Santarém (SAN), between SAN and the Atlantic coast. Using a simple mass balance approach, we find substantial CH4 emissions with an annual average flux of 52.8 ± 6.8 mg CH4 m−2 d−1 over an area of approximately 1 × 106 km2. Fluxes are highest in two periods of the year: in the beginning of the wet season and during the dry season. Using a CO:CH4 emission factor estimated from the profile data, we estimated a contribution of biomass burning of around 15% to the total flux in the dry season, indicating that biogenic emissions dominate the CH4 flux. This 13 year record shows that CH4 emissions upwind of SAN varied over the years, with highest emissions in 2008 (around 25% higher than in 2007), mainly during the wet season, representing 19% of the observed global increase in this year.
Validation of the global distribution of CO2 volume mixing ratio in the mesosphere and lower thermosphere from SABER
Authors: Rezac L. , Jian Y. , Yue J. , Russell J. M. , Kutepov A. , Garcia R. , Walker K. , Bernath P.
Published: November 2015

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has been measuring the limb radiance in 10 broadband infrared channels over the altitude range from ~ 400 km to the Earth's surface since 2002. The kinetic temperatures and CO2 volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3 µm under nonlocal thermodynamic equilibrium (non‐LTE) conditions. This paper presents results of a validation study of the SABER CO2 VMRs obtained with a two‐channel, self‐consistent temperature/CO2 retrieval algorithm. Results are based on comparisons with coincident CO2 measurements made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE‐FTS) and simulations using the Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD‐WACCM). The SABER CO2 VMRs are in agreement with ACE‐FTS observations within reported systematic uncertainties from 65 to 110 km. The annual average SABER CO2 VMR falls off from a well‐mixed value above ~80 km. Latitudinal and seasonal variations of CO2 VMRs are substantial. SABER observations and the SD‐WACCM simulations are in overall agreement for CO2 seasonal variations, as well as global distributions in the mesosphere and lower thermosphere. Not surprisingly, the CO2 seasonal variation is shown to be driven by the general circulation, converging in the summer polar mesopause region and diverging in the winter polar mesopause region.
Modeling the Arctic freshwater system and its integration in the global system: Lessons learned and future challenges
Authors: Lique Camille , Holland Marika M. , Dibike Yonas B. , Lawrence David M. , Screen James A.
Published: November 2015

Numerous components of the Arctic freshwater system (atmosphere, ocean, cryosphere, and terrestrial hydrology) have experienced large changes over the past few decades, and these changes are projected to amplify further in the future. Observations are particularly sparse, in both time and space, in the polar regions. Hence, modeling systems have been widely used and are a powerful tool to gain understanding on the functioning of the Arctic freshwater system and its integration within the global Earth system and climate. Here we present a review of modeling studies addressing some aspect of the Arctic freshwater system. Through illustrative examples, we point out the value of using a hierarchy of models with increasing complexity and component interactions, in order to dismantle the important processes at play for the variability and changes of the different components of the Arctic freshwater system and the interplay between them. We discuss past and projected changes for the Arctic freshwater system and explore the sources of uncertainty associated with these model results. We further elaborate on some missing processes that should be included in future generations of Earth system models and highlight the importance of better quantification and understanding of natural variability, among other factors, for improved predictions of Arctic freshwater system change.
Is the Teisseyre‐Tornquist Zone an ancient plate boundary of Baltica?
Authors: Mazur Stanislaw , Mikolajczak Mateusz , Krzywiec Piotr , Malinowski Michal , Buffenmyer Vinton , Lewandowski Marek
Published: November 2015

The Teisseyre‐Tornquist Zone (TTZ) is generally regarded as a fossil plate boundary in Europe that extends 2000 km from the Baltic Sea to the Black Sea. We used an integrated approach merging potential fields and seismic data to explore crustal architecture across the TTZ in central Poland. The aim of the study was to test whether the TTZ coincides with an early Paleozoic (Caledonian) suture formed through the closure of the Tornquist Ocean along the SW Baltica margin. The suture is presumed to separate the East European Craton (EEC) from the Paleozoic terranes of Western Europe. Two seismic reflection lines from the PolandSPAN™ experiment were used to image the deep structure at the SW margin of the EEC. Lines PL‐5300 and PL‐5400 run NE‐SW in central and northern Poland, respectively. The seismic interpretation down to top of basement was integrated with 2‐D gravity and magnetic modeling to highlight the structure of the deep crust. Both the gravity and magnetic models show a suture that welds together two blocks at the base of crust. However, top of basement above the suture dips uniformly to the SW and is overlain by undisturbed lower Paleozoic and younger sediments. By implication, the suture must have developed in the Precambrian and both crustal blocks amalgamated belong to the EEC. Consequently, the Caledonian suture, formed by the closure of the Tornquist Ocean between Avalonia and Baltica, must be located farther southwest beneath thick upper Paleozoic and Mesozoic sediments.
Modeling of Retention in Reversed Phase Liquid Chromatography
Authors: García‐Alvarez‐Coque Maria C. , Ramis‐Ramos Guillermo , Torres‐Lapasió José R. , Ortiz‐Bolsico C.
Published: November 2015

Interpretive optimization strategies in liquid chromatography are based on the accurate description (modeling) of the chromatographic behavior. The first step in these strategies consists of gathering information about the compounds in the sample, usually attending only to retention and covering reasonably wide regions of the factors involved. For each solute, a relationship that describes the retention is obtained as a function of the experimental factors. This function will allow the prediction of isocratic or gradient retention times for a given solute under different conditions. This chapter presents an overview of retention modeling in reversed phase liquid chromatography (RPLC). The most widely used models for stationary‐phase characterization are outlined. The chapter also talks about isocratic elution, dead time estimation, the influence of temperature on retention, prediction in retention, gradient elution, computer‐assisted interpretive optimization, and the hydrophobic subtractive model.
Chemometrics in Data Analysis and Liquid Chromatographic Method Development
Authors: Jančić‐Stojanović Biljana , Rakić Tijana
Published: November 2015

This chapter talks about the two important fields of chemometrics used to resolve chromatographic problems. The first part of the chapter presents the techniques for managing the large number of data obtained from chromatographic analysis. The second part overviews the chemometric applications in liquid chromatography (LC) method development. The advantages of chemometric approaches over the traditionally applied trial and error approaches is observed through the full control gained by the analyst over all important quality characteristics. The most significant problems that appear in chromatographic analysis are baseline and noise, retention time shift, incomplete separation, and data overloading. All these problems can be solved during preprocessing using chemometrics. The chapter gives special attention given to the application of chemometrics in the development of LC methods in accordance with modern QbD principles explaining in detail the systematic approach to the creation of highly reliable chromatographic methods.
Micellar Liquid Chromatography: Fundamentals
Authors: García‐Alvarez‐Coque Maria C. , Ruiz‐Angel Maria J. , Carda‐Broch Samuel
Published: November 2015

The reversed phase liquid chromatography (RPLC) mode with surfactant above the critical micellar concentration (CMC) has been called micellar liquid chromatography (MLC). In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant‐modified stationary phase, bulk aqueous solvent, and micellar pseudo‐phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant‐modified stationary phase, bulk aqueous solvent, and micellar pseudo‐phase. In pure micellar mobile phases, water‐insoluble nonpolar solutes or species strongly bound to surfactant monomers do not participate significantly in the aqueous environment of the three‐phase partitioning scheme. Some of the solutions proposed along the years to overcome these limitations have favored the potential of the technique, but they have not resulted in an extensive use.
Micellar Liquid Chromatography: Method Development and Applications
Authors: García‐Alvarez‐Coque Maria C. , Ruiz‐Angel Maria J. , Carda‐Broch Samuel
Published: November 2015

After more than three decades of experience, micellar liquid chromatography (MLC) seems to be an alternative to conventional reversed phase liquid chromatography (RPLC) with hydro‐organic mobile phases, with increasing interest in “green” chemistry. MostMLCprocedures use hybrid micellar mobile phases containing a surfactant (frequently sodium dodecyl sulfate) above the critical micellar concentration and a relatively small amount of organic solvent to increase the elution strength and improve the efficiencies. Practical indications a chromatographer should consider inMLCwhen developing an analytical procedure, related to the mobile‐phase preparation and the cautions with the stationary phase, are discussed. The retention models to be considered for optimizing the best experimental conditions, taking the concentrations of surfactant and organic solvent and the pH as factors, and the diverse detection modes that have been used inMLCare described. The direct injection capability ofMLCafter simple filtration is highlighted. A compilation of analytical methods inMLCis given, mainly related to the determination of drugs in formulations and physiological fluids, oriented to follow the parent drug and/or its metabolites.
Affinity Chromatography
Authors: Pfaunmiller Erika L. , Bas Jesbaniris , Brooks Marissa , Milanuk Mitchell , Rodriguez Elliott , Vargas John , Matsuda Ryan , Hage David S.
Published: November 2015

Affinity chromatography is a form of liquid chromatography that uses a biologically‐related binding agent as the stationary phase. This separation method can be highly selective, making it valuable for the purification, pretreatment, or analysis of many biologically relevant molecules. This chapter discusses the basic principles of affinity chromatography and the factors that need to be considered in the development or use of this technique. Several possible binding agents that can be employed in this method will be examined, including biological ligands such as antibodies, lectins, and nucleic acids, as well as nonbiological ligands such as boronic acids, metal ion chelates, and biomimetic dyes. The types of support materials and immobilization methods that can be utilized in this method are described, along with the application and elution conditions that are commonly used in affinity chromatography. A summary of the applications for this method are provided, including its use in biomolecule purification, sample pretreatment, chemical analysis, and studies of biological interactions. Recent developments and future directions for this area are also described.
New Essential Events in Modern Applications of Inverse Gas Chromatography
Authors: Voelkel Adam , Grajek Henryk , Strzemiecka Beata , Adamska Katarzyna
Published: November 2015

Inverse gas chromatography (IGC) may be realized in two modes: at finite concentration of test solutes, FC‐IGC, or in the region of infinitive dilution ID‐IGC. The properties of solid materials in IGC are expressed by several parameters describing its ability for the dispersive and specific acid‐base interactions. In the design process and in the obtaining of complex systems such as mixtures and formulations consisting of various components, it is important to know their characteristics, expressed by the physicochemical parameters. One of the potential solutions is to determine the cohesion energy components or, more specifically, the solubility parameter. A proper description of the elution peak profile has an impact on the precise determination of the time of the end of the analyte elution from an adsorbent bed in a column or from a layer of the stationary phase deposited on an inert support or on a column wall.
Trends in
CE
‐
MS
and Applications
Authors: Tycova Anna , Foret Frantisek
Published: November 2015

Capillary electrophoresis coupled to mass spectrometry with electrospray ionization (
CE
‐
ESI
‐
MS
) is becoming a very powerful tool utilized not only in academic research but also in industrial applications. This overview covers mainly the research published in the past decade and is divided into two main parts. Since the crucial parameter of the
CE
‐
MS
is the interface design, the first part of this chapter covers the instrumentation developments. The second part covers selected applications of the
CE
‐
ESI
‐
MS
in the field of proteomics, glycomics and metabolomics.
Capillary Electrochromatography
Authors: Zhang Kai , Gao Ruyu
Published: November 2015

Capillary electrochromatography (
CEC
) is a hybrid microseparation technique that combines the high selectivity of high‐performance liquid chromatography (
HPLC
) and the high efficiency of capillary electrophoresis (
CE
).
CEC
holds unique advantages such as high separation power, high selectivity, high sensitivity, short analysis time, low consumption of samples and chemicals, and good compatibility with mass spectrometry (
MS
). Accordingly, it has attracted extensive attentions over the past decades. Recent progresses in
CEC
, especially the development of
CEC
stationary phases, such as fused silica‐packed columns, open tubular coating columns, monolithic columns, and molecular imprinted polymer columns, as well as the application of CEC in chiral separation and peptide/protein analysis, are summarized in this chapter.
High‐Performance Thin‐Layer Chromatography
Authors: Cebolla Vicente L. , Membrado Luis , Jarne Carmen , Garriga Rosa
Published: November 2015

The instrumental modularity of its basic steps, that is, sample application, chromatographic development, and detection, confersHPTLCa high degree of flexibility. Automated and computer‐controlled instruments with different levels of sophistication for each of these steps have been developed, for example, spray‐on sample applicators and chambers including the possibility of gradient separation. Detection techniques such as scanning densitometers, electronic documentation systems, bioactivity detection methodologies, and online coupling with mass spectrometry have come to be easily and firmly established in laboratories. Particularly, the introduction of an elution‐basedTLC–MSinterface has not only allowed original and efficient hyphenated systems to be designed but also opened the possibility of expanding the connection with other detectors. Thanks to this instrumental development,HPTLChas become a reliable, accurate, and sensitive analytical technique.
Preparative Chromatography: Batch and Continuous
Authors: Aniceto José P.S. , Silva Carlos M.
Published: November 2015

Chromatography, although initially prevalent in the analytical field, is increasingly extended as a preparative process for the commercial scale production of several chemicals whose separation from feed streams is difficult to achieve by conventional methods. In this chapter, the most relevant and recent preparative chromatography approaches are presented and discussed, divided in terms of batch and continuous processes. The fundamental conservation equations, kinetic laws, and equilibrium relations governing chromatographic systems are presented in detail as they are common to all processes modeling. Several models and approaches are presented in an order of higher approximation to reality that necessarily results in an increasing degree of mathematical sophistication. This complexity trend is linked to the sequential introduction of the various phenomena that take place inside the adsorption bed. In particular, the influence of finite mass transfer resistances and axial dispersion upon the dynamic behavior of the chromatographic system is highlighted. With regard to batch chromatography, the most frequent techniques, such as preparativeHPLCand supercritical fluid chromatography are covered, along with key chromatography concepts. Closed loop recycling chromatography and steady‐state recycling chromatography are recycling techniques that may be situated between batch and continuous strategies, being able to enhance the performance of batch systems while avoiding the higher complexity inherent to continuous approaches. Regarding continuous chromatography, the development of the simulated moving bed (SMB) technology has allowed improved productivity, product's purities, and lower operating costs compared to batch processing. Since its inception, several different strategies and modifications to the conventionalSMBhave been proposed. The well‐established and the most innovativeSMBoperation modes, such as intermittent‐SMB, supercriticalSMB, and variable external streams systems, are presented and discussed, along with the necessary equipment designs that allow their implementation. Other continuous chromatographic processes include the high‐speed countercurrent chromatography and the centrifugal partition chromatography, both involving two immiscible liquid phases, and annular chromatography that permits continuous operation while using a stationary phase. Some brief remarks are made on equipment and system designs.
Dispersive Solid‐Phase Extraction
Authors: Socas‐Rodríguez Bárbara , Herrera‐Herrera Antonio V. , Asensio‐Ramos María , Hernández‐Borges Javier
Published: November 2015

Dispersive solid‐phase extraction (dSPE) is a sorbent‐based technique widely applied in sample preparation for both sample clean up or analite preconcentration. It shows considerable benefits over conventionalSPE, especially in terms of the simplicity of the procedure. This chapter aims at providing a general overview ofdSPE, its different extraction approaches (dSPE, µ‐dSPEand magnetic‐dSPE), and the principal factors which influence the extraction process (including the sorbents most frequently used) as well as its most common applications.
Analytical Supercritical Fluid Extraction
Authors: Martínez Julian , de Aguiar Ana Carolina
Published: November 2015

The principles of analytical supercritical fluid extraction (SFE) are discussed. Specific sections include supercritical fluids, SFE, and supercritical fluid fractionation, instrumentation for SFE for a basic extraction system, comparison between SFE and conventional techniques, and applications of analytical SFE. The chapter concludes with a discussion on the present scenario and prospects for SFE as an analytical technique.
Extraction Methods Facilitated by the use of Magnetic Nanoparticles
Authors: Rocío‐Bautista Priscilla , Pino Verónica
Published: November 2015

Magnetic nanoparticles (MNPs) are a group of nanoparticles (NPs) that present superparamagnetic properties. MNPs are composed of a magnetic solid phase that is responsible for the magnetic properties. The characterization of MNPs is usually accomplished using techniques such as X‐ray diffraction (XRD), transmission electron microscopy (TEM), or scanning electron microscopy (SEM). Several review articles have been recently devoted to MNPs in analytical chemistry and particularly to sample preparation. This chapter presents extraction methods facilitated by the use of MNPs, with particular emphasis on MNP types and extraction applications. The relatively simple tuneability of MNPs, by easily anchoring task‐specific sorbents of quite different nature (silica based, carbon and derivatives based, polymeric based, and so on), opens a number of possible combinations and enormously extends its future applications
Sample Derivatization in Separation Science
Authors: Cardinael Pascal , Casabianca Hervé , Peulon‐Agasse Valerie , Berthod Alain
Published: November 2015

Chromatographic methods have made so much progress that they are today the method of choice in analytical laboratories. Not all molecules can be separated by the desired method. Derivatization reactions are simple chemical modification of the sample that will render it compatible with the selected separation method. Gas chromatography (
GC
) can separate volatile and thermostable compounds. The possible derivatization reactions that will enhance both volatility and thermal resistance of the solutes are summarized and the protocols are outlined.
Liquid chromatography
(
LC
) can separate solutes soluble in the mobile phase. The main problem is to detect them. Derivatization reactions in
LC
will modify the solutes adding a chomophore for easy
UV
detection or a fluorophore for sensitive fluorescent detection. Different protocols including pre‐ or postcolumn reactions are described. Capillary electrophoresis (
CE
) separates solutes by difference in electrophoretic mobility. Derivatization reactions in
CE
are similar to derivatization in
LC
when detection is the problem. On‐column and postcolumn derivatizations are common in
CE
. Derivatization to change the solute electrophoretic mobility can also be performed.
Validation of Analytical Methods Based on Chromatographic Techniques: An Overview
Authors: Peris‐Vicente Juan , Esteve‐Romero Josep , Carda‐Broch Samuel
Published: November 2015

Method validation is an important requirement in the analysis by liquid (HPLC) or gas (GC) chromatography. However, some analytical chemists seem unaware about its importance. They show serious doubt about the main aspects of validation: need, when it must be performed, its relationship with the development of the method and the correct procedure. Although a large number of indications and advices about validation can be found in the literature, they refer to specific methods, and are often underutilized. Several analysts consider that the validation must be mandatorily performed by a collaborative trial between several laboratories, and they are not willing to carry it out. A wide range of guidelines describing the parameters and indicating directives about the achievement of validation have also been issued. The understanding of the analysts about the process of method validation is inhibited because the terminology and methodology of the validation parameters depend on the scope and the guideline. The validation is applied with a specific objective, through a defined protocol, for the determination of a specific analyte inside an explicit working range. The validation should usually verify that the method effectively provides reliable results when applied to the predefined scope and using the established operating conditions. The scope of the analysis, a description of the analytical requirements needed to achieve the objectives of the analysis, must be clearly defined before starting the validation to select the adequate guideline and correctly conduct the validation process.

This chapter describes the concept of method validation, referred to the analysis of organic compounds in liquid and gas chromatography. The need to establish the performances and the limits of a method and to evaluate its suitability for a specific purpose is revised. The increasing interest from researchers and regulatory agencies on validation during the past few years has been discussed by surveying the articles published and guidelines issued on this topic. Several approaches to correctly accomplish the validation have been detailed. Furthermore, the validation parameters, which should be evaluated, will be methodically described, and a thorough comparison between the main validation guides is provided.
Chiral Liquid Chromatography: Recent Applications with Special Emphasis on the Enantioseparation of Amino Compounds
Authors: Ilisz István
Published: November 2015

The biological and chemical properties determined by the molecular asymmetry play an especially important role in nature. If a racemic compound comes in contact with a chirally selective living system, the effects of the enantiomers may be different, resulting in different biological consequences, division, metabolism, excretion, and so on. Accordingly, a demand has arisen in pharmaceutical and other therapeutic fundamental research for the analytical qualification and quantification of chiral products. High‐performance liquid chromatography (HPLC) on chiral stationary phases is an effective analytical tool for the resolution of chiral compounds on both analytical and preparative scales. This chapter summarizes the directHPLCseparations applying different types of chiral stationary phases; however, indirect methods are also briefly discussed.
Nanoimprinted, Submicrometric, MOF‐Based 2D Photonic Structures: Toward Easy Selective Vapors Sensing by a Smartphone Camera
Authors: Dalstein Olivier , Ceratti Davide R. , Boissière Cédric , Grosso David , Cattoni Andrea , Faustini Marco
Published: November 2015

In this work, a soft‐lithographic approach to fabricate submicrometer metal organic framework (MOF)‐based 2D photonic structures is described. Nanometric zeolitic imidazole framework material ZIF‐8 (zinc) is chosen as the sensible MOF material because of its chemical stability and its vapor selective adsorption properties. Two different systems are fabricated: nanopatterned colloidal ZIF‐8 homo‐ and ZIF‐8/TiO2 heterostructures. Several features (stripes, squares, etc.) with dimensions of 200 nm are replicated on different substrates such as silicon, flexible plastics, and even aluminum cans, over relatively large surfaces (up to 1 cm2). In addition, the use of these photonic MOF‐heterostructures as very low‐cost sensing platforms compatible with smartphone technology is demonstrated. This method relies on the evaluation of the change in diffraction efficiency of the photonic MOF‐patterns, induced by the MOF refractive index variation, which is simply detected by a charge coupled device (CCD) camera, as those integrated in smartphones, without need for complex optical instrumentations for transduction data processing. Performances of the sensors are first evaluated using isopropyl alcohol adsorption/desorption cycling as a model case. In addition, a “real” environmental issue is tackled. Selective detection of styrene in presence of interfering water is demonstrated at concentrations below the human permissible exposure limit. In situ ellispometric analyses are also carried out in order to confirm the sensor performances and to propose a mechanism for styrene uptake into the nanoMOFs.
Tunable Self‐Assembled Micro/Nanostructures of Carboxyl‐Functionalized Squarylium Cyanine for Ammonia Sensing
Authors: Li Jie , Lv Baozhong , Yan Dongpeng , Yan Shouke , Wei Min , Yin Meizhen
Published: November 2015

Orderly molecular self‐assembly for tunable micro/nanostructures is an effective way to prepare novel functional materials with desired properties. Squarylium cyanine (SCy) dyes have received great attention in the fields of laser, imaging, and optoelectronic device. However, the detailed self‐assembly behavior of SCy has rarely been investigated. In the present work, two SCy derivatives, D1 and D2, respectively, bearing four and two carboxylic acid groups at different positions are prepared and used as a model system to investigate the molecular self‐assembly, morphology, and optical properties of SCy dyes. The hydrogen‐bonding interactions between the carboxylic acid groups in D1 and D2 are determined with X‐ray diffraction, 2D nuclear magnetic resonance, and Fourier transformation infrared spectroscopy. The two types of hydrogen bonds in D1 cooperating with inherent π–π stacking interaction result in tunable molecular aggregations, which further leads to the transformation between J‐aggregation and H‐aggregation of D1 in the solid state in response to ammonia gas. In all, this work provides a feasible and effective way to study the self‐assembled aggregates of SCy dyes at both molecular and supramolecular levels, and has developed a reversible sensor for ammonia gas detection.
Sustainable Synthesis and Assembly of Biomass‐Derived B/N Co‐Doped Carbon Nanosheets with Ultrahigh Aspect Ratio for High‐Performance Supercapacitors
Authors: Ling Zheng , Wang Zhiyu , Zhang Mengdi , Yu Chang , Wang Gang , Dong Yanfeng , Liu Shaohong , Wang Yuwei , Qiu Jieshan
Published: November 2015

The practical application of graphene has still been hindered by high cost and scarcity in supply. It boosts great interest in seeking for low‐cost substitute of graphene for upcoming usage where extremely physical properties are not absolutely critical. The conversion of renewable biomass offers a great opportunity for sustainable and economic fabrication of 2D carbon nanostructures. However, large‐scale production of carbon nanosheets with ultrahigh aspect ratio, satisfied electronic properties, and the capability of organized assembly like graphene has been rarely reported. In this work, a facile yet efficient approach for mass production of flexible boric/nitrogen co‐doped carbon nanosheets with very thin thickness of 5–8 nm and ultrahigh aspect ratio of over 6000–10 000 is demonstrated by assembling the biomass molecule in long‐range order on 2D hard template and subsequent annealing. The advantage of these doped carbon nanosheets over conventional products lies in that they can be readily assembled to multilevel architectures such as freestanding flexible thin film and ultralight aerogels with better electrical properties, which exhibit exceptional capacitive performance for supercapacitor application. The recyclability of boric acid template further reduces the discharge of the waste and processing cost, rendering high cost‐effectiveness and environmental benignity for scalable production.
Quasi 2D Ultrahigh Carrier Density in a Complex Oxide Broken‐Gap Heterojunction
Authors: Xu Peng , Droubay Timothy C. , Jeong Jong Seok , Mkhoyan K. Andre , Sushko Peter V. , Chambers Scott A. , Jalan Bharat
Published: November 2015

Two‐dimensional (2D) ultra‐high carrier densities are of considerable current research interest for novel plasmonic and high charge‐gain devices. However, the highest 2D electron density obtained is thus far limited to 3 × 1014 cm–2 (½ electron/unit cell/interface) at GdTiO3/SrTiO3interfaces, and is typically an order of magnitude lower at LaAlO3/SrTiO3interfaces. We show from experiment and modeling that carrier densities much higher than expected based on resolution of the polar discontinuity at perovskite oxide heterojunctions can be achieved via band engineering. The SrTiO3(8 u.c.)/NdTiO3(tu.c)/SrTiO3(8 u.c.)/LSAT(001) heterostructure shows the expected electronic reconstruction behavior starting att= 2 u.c., but then exhibits a higher carrier density regime att≥ 6 u.c. due to additional charge transfer from band alignment.
Understanding Interface Engineering for High‐Performance Fullerene/Perovskite Planar Heterojunction Solar Cells
Authors: Liu Yao , Bag Monojit , Renna Lawrence A. , Page Zachariah A. , Kim Paul , Emrick Todd , Venkataraman D. , Russell Thomas P.
Published: November 2015

Interface engineering is critical for achieving efficient solar cells, yet a comprehensive understanding of the interface between a metal electrode and electron transport layer (ETL) is lacking. Here, a significant power conversion efficiency (PCE) improvement of fullerene/perovskite planar heterojunction solar cells from 7.5% to 15.5% is shown by inserting a fulleropyrrolidine interlayer between the silver electrode and ETL. The interface between the metal electrode and ETL is carefully examined using a variety of electrical and surface potential techniques. Electrochemical impedance spectroscopy (EIS) measurements demonstrate that the interlayer enhances recombination resistance, increases electron extraction rate, and prolongs free carrier lifetime. Kelvin probe force microscopy (KPFM) is used to map the surface potential of the metal electrode and it indicates a uniform and continuous work function decrease in the presence of the fulleropyrrolidine interlayer. Additionally, the planar heterojunction fullerene/perovskite solar cells are shown to have good stability under ambient conditions.
Spectroscopic Insight into Li‐Ion Batteries during Operation: An Alternative Infrared Approach
Authors: Alves Dalla Corte Daniel , Caillon Georges , Jordy Christian , Chazalviel Jean‐Noël , Rosso Michel , Ozanam François
Published: November 2015

Multiple‐internal‐reflection infrared spectroscopy allows for the study of thin‐film amorphous silicon electrodes in situ and in operando, in conditions typical of those used in Li‐ion batteries. It brings an enhanced sensitivity, and the attenuated‐total‐reflection geometry allows for the extraction of quantitative information. When electrodes are cycled in representative electrolytes, the simultaneously recorded infrared spectra give an insight into the solid/electrolyte interphase (SEI) composition. They also unravel the dynamic behavior of this SEI layer by quantitatively assessing its thickness, which increases during silicon lithiation and partially decreases during delithiation. Li‐ion solvation effects in the vicinity of the electrode indicate that lithium incorporation in the solid phase is the rate‐determining step of the electrochemical processes during lithiation. The lithiation of the active material also results in the irreversible consumption of a large quantity of hydrogen in the pristine material. Finally, the evolution of the electronic absorption of the electrode material suggests that lithium diffusion is much easier after the first lithiation than in the pristine material. Therefore, in situ Fourier‐transform infrared spectroscopy performed in a well‐suited configuration efficiently extracts original and quantitative pieces of information on the surface and bulk phenomena affecting Li‐ion electrodes during their operation in realistic conditions.
Influence of slip on the flow of a yield stress fluid around a flat plate
Authors: Ahonguio Fiacre , Jossic Laurent , Magnin Albert
Published: November 2015

This experimental study deals with the influence of slip on the non‐inertial flow of a viscoplastic fluid around a flat plate moving at a constant velocity. The bulk and interfacial properties of the fluid have been finely characterized. The drag force has been analyzed with regards to the flow velocity and for two tribological conditions: adherence and slip. This force decreases with the velocity and is reduced in the presence of slip. Kinematic fields have also been measured by Particle Image Velocimetry (PIV), to determine the influence of both the velocity and the tribological conditions on the liquid and solid regions of the flow. The results highlight no significant influence of the flow velocity on the thickness of the boundary layer and rigid zones. The wall shear stresses along the plate obtained from force measurements and slip velocities are then compared to rheometrical measurements. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1356–1363, 2016
Tooth wear and feeding ecology in mountain gorillas from Volcanoes National Park, Rwanda
Authors: Galbany Jordi , Imanizabayo Olive , Romero Alejandro , Vecellio Veronica , Glowacka Halszka , Cranfield Michael R. , Bromage Timothy G. , Mudakikwa Antoine , Stoinski Tara S. , McFarlin Shannon C.
Published: November 2015

Objectives

Ecological factors have a dramatic effect on tooth wear in primates, although it remains unclear how individual age contributes to functional crown morphology. The aim of this study is to determine how age and individual diet are related to tooth wear in wild mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park, Rwanda.

Material and Methods

We calculated the percent of dentine exposure (PDE) for all permanent molars (M1–M3) of known‐age mountain gorillas (N = 23), to test whether PDE varied with age using regression analysis. For each molar position, we also performed stepwise multiple linear regression to test the effects of age and percentage of time spent feeding on different food categories on PDE, for individuals subject to long‐term observational studies by the Dian Fossey Gorilla Fund International's Karisoke Research Center.

Results

PDE increased significantly with age for both sexes in all molars. Moreover, a significant effect of gritty plant root consumption on PDE was found among individuals. Our results support prior reports indicating reduced tooth wear in mountain gorillas compared to western gorillas, and compared to other known‐aged samples of primate taxa from forest and savanna habitats.

Discussion

Our findings corroborate that mountain gorillas present very low molar wear, and support the hypothesis that age and the consumption of particular food types, namely roots, are significant determinants of tooth wear variation in mountain gorillas. Future research should characterize the mineral composition of the soil in the Virunga habitat, to test the hypothesis that the physical and abrasive properties of gritty foods such as roots influence intra‐ and interspecific patterns of tooth wear. Am J Phys Anthropol 159:457–465, 2016. © 2015 Wiley Periodicals, Inc.
QM/MM‐Simulationen ergeben synergetische Substrat‐ und Sauerstoffaktivierung in Salicylat‐Dioxygenase
Authors: Roy Subhendu , Kästner Johannes
Published: November 2015

Salicylat‐1,2‐Dioxygenase (SDO) ist das erste bekannte Enzym, das die oxidative Spaltung eines einfach hydroxylierten Aromaten, Salicylat, statt der wohlbekannten elektronenreichen Substrate katalysiert. Wir haben den Mechanismus der Sauerstoffaktivierung in SDO mit QM/MM‐Simulationen untersucht. Unsere Ergebnisse zeigen, dass das Nicht‐Häm‐FeII‐Zentrum in SDO Salicylat und O2 gemeinsam durch eine starke kovalente Wechselwirkung aktiviert, um die reduktive Spaltung von O2 zu ermöglichen. Die reaktive Sauerstoffspezies ist ein kovalenter Salicylat‐FeII‐O2‐Komplex, wobei die Elektronenstruktur zwischen den beiden Grenzfällen FeII‐O2 und FeII‐O2.− mit partiellem Elektronentransfer vom aktivierten Salicylat zu O2 über das Fe‐Zentrum liegt. Folglich verwendet SDO eine synergetische Strategie der Substrat‐ und Sauerstoffaktivierung, um die katalytische Reaktion auszuführen, die einmalig in der Familie der Eisendioxygenasen ist. Darüber hinaus erfolgt die O2‐Aktivierung in SDO ohne die Hilfe einer Protonenquelle. Unsere Studie zeigt eine bisher unbekannte Möglichkeit für den Mechanismus der O2‐Aktivierung.
Capture of CO2 by a Cationic Nickel(I) Complex in the Gas Phase and Characterization of the Bound, Activated CO2 Molecule by Cryogenic Ion Vibrational Predissociation Spectroscopy
Authors: Menges Fabian S. , Craig Stephanie M. , Tötsch Niklas , Bloomfield Aaron , Ghosh Subrata , Krüger Hans‐Jörg , Johnson Mark A.
Published: November 2015

We describe a systematic method for the preparation and spectroscopic characterization of a CO2 molecule coordinated to an activated bisphenoidal nickel(I) compound containing a tetraazamacrocyclic ligand in the gas phase. The resulting complex was then structurally characterized by using mass‐selected vibrational predissociation spectroscopy. The results indicate that a highly distorted CO2 molecule is bound to the metal center in an η2‐C,O coordination mode, thus establishing an efficient and rational method for the preparation of metal‐activated CO2 for further studies using ion chemistry techniques.
Plasmonic/Nonlinear Optical Material Core/Shell Nanorods as Nanoscale Plasmon Modulators and Optical Voltage Sensors
Authors: Yin Anxiang , He Qiyuan , Lin Zhaoyang , Luo Liang , Liu Yuan , Yang Sen , Wu Hao , Ding Mengning , Huang Yu , Duan Xiangfeng
Published: November 2015

Herein, we report the design and synthesis of plasmonic/non‐linear optical (NLO) material core/shell nanostructures that can allow dynamic manipulation of light signals using an external electrical field and enable a new generation of nanoscale optical voltage sensors. We show that gold nanorods (Au NRs) can be synthesized with tunable plasmonic properties and function as the nucleation seeds for continued growth of a shell of NLO materials (such as polyaniline, PANI) with variable thickness. The formation of a PANI nanoshell allows dynamic modulation of the dielectric environment of the plasmonic Au NRs, and therefore the plasmonic resonance characteristics, by an external electrical field. The finite element simulation confirms that such modulation is originated from the field‐induced modulation of the dielectric constant of the NLO shell. This approach is general, and the coating of the Au NRs with other NLO materials (such as barium titanate, BTO) is found to produce a similar effect. These findings can not only open a new pathway to active modulation of plasmonic resonance at the sub‐wavelength scale but also enable the creation of a new generation of nanoscale optical voltage sensors (NOVS).
Transferhydrosilylierung
Authors: Oestreich Martin
Published: November 2015

Es steht außer Frage, dass Transferhydrierung ein gängiges Verfahren in der Industrie und der akademischen Welt ist. Trotz ihrer Vielfältigkeit war die konzeptionell verwandte Transferhydrosilylierung bis zur jüngsten Entwicklung einer radikalischen und einer ionischen Variante im Grunde unbekannt gewesen. Die neuen Methoden basieren beide auf dem Motiv eines siliciumsubstituierten Cyclohexa‐1,4‐diens und hängen von der Aromatisierung der entsprechenden radikalischen bzw. kationischen Cyclohexadienylzwischenstufen begleitet von homo‐ oder heterolytischer Spaltung der Si‐C‐Bindung ab. Die radikalische und ionische Transferhydrosilylierung werden in diesem Kurzaufsatz miteinander in Bezug gesetzt, und frühe Hinweise auf die Möglichkeit einer Transferhydrosilylierung werden auch berücksichtigt. Der derzeitige Stand der Forschung befindet sich zweifellos noch in den Anfängen, aber die jüngsten Fortschritte lassen das vielversprechende Potenzial von Transferhydrosilylierungen bereits erkennen.
Synergistic Substrate and Oxygen Activation in Salicylate Dioxygenase Revealed by QM/MM Simulations
Authors: Roy Subhendu , Kästner Johannes
Published: November 2015

Salicylate 1,2‐dioxygenase (SDO) is the first enzyme to be discovered to catalyze the oxidative cleavage of a monohydroxylated aromatic compound, namely salicylate, instead of the well‐known electron‐rich substrates. We have investigated the mechanism of dioxygen activation in SDO by QM/MM calculations. Our study reveals that the non‐heme FeII center in SDO activates salicylate and O2 synergistically through a strong covalent interaction to facilitate the reductive cleavage of O2. A covalent salicylate–FeII–O2 complex is the reactive oxygen species in this case, and its electronic structure is best described as being between the two limiting cases, FeII−O2 and FeII−O2.−, with partial electron transfer from the activated salicylate to O2 via the Fe center. Thus SDO employs a synergistic strategy of substrate and oxygen activation to carry out the catalytic reaction, which is unprecedented in the family of iron dioxygenases. Moreover, O2 activation in SDO happens without the assistance of a proton source. Our study essentially shows a new mechanistic possibility for O2 activation.
Stabilization of a Silaaldehyde by its η2 Coordination to Tungsten
Authors: Fukuda Tetsuya , Hashimoto Hisako , Sakaki Shigeyoshi , Tobita Hiromi
Published: November 2015

Treatment of pyridine‐stabilized silylene complexes [(η5‐C5Me4R)(CO)2(H)WSiH(py)(Tsi)] (R=Me, Et; py=pyridine; Tsi=C(SiMe3)3) with an N‐heterocyclic carbene MeIiPr (1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) caused deprotonation to afford anionic silylene complexes [(η5‐C5Me4R)(CO)2WSiH(Tsi)][HMeIiPr] (R=Me (1‐Me); R=Et (1‐Et)). Subsequent oxidation of 1‐Me and 1‐Et with pyridine‐N‐oxide (1 equiv) gave anionic η2‐silaaldehydetungsten complexes [(η5‐C5Me4R)(CO)2W{η2‐OSiH(Tsi)}][HMeIiPr] (R=Me (2‐Me); R=Et (2‐Et)). The formation of an unprecedented W‐Si‐O three‐membered ring was confirmed by X‐ray crystal structure analysis.