bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Chromatography with Mass Spectrometry (GC‐MS)
Authors: Vetter Walter 
Published: November 2015

AbstractThe linking of gas chromatography with mass spectrometry (GC–MS) has resulted in one of the most powerful separation techniques for volatile compounds. This chapter addresses important contributions from theGCside ranging from capillary columns over comprehensive two‐dimensional gas chromatography (GC × GC) to the potential of using hydrogen as the carrier gas. Important innovations from theMSside are highlighted in the form of classic and modern approaches in mass separation, new ion source designs, modern high‐resolution techniques and pyrolysisGC–MS. Special sections feature the use ofselected ion monitoring (SIM) and selected reaction monitoring (SRM) modes, targeted and nontargeted approaches, and structure investigation strategies byGC/MS. These key topics are further discussed with new applications in the analysis of fatty acids, flavor compounds, pollutants, drugs, and metabolomics. Finally,GChyphenated to isotope ratio mass spectrometry (GC–IRMS) for stable carbon isotope analysis is described in theory and with applications in major application areas.
Packed Column Sub‐ and Supercritical Fluid Chromatography
Authors: West Caroline , Khater Syame , Lesellier Eric 
Published: November 2015

AbstractSub‐ and supercritical fluid chromatography (SFC) are the terms currently accepted to describe chromatography with carbon dioxide ‐ based mobile phases . While capillary SFC was first developed in the early years, packed column SFC has now taken the lead and will be described in this chapter. The characteristics of the fluids employed in SFC (low viscosity , high diffusivity, compressibility, and tunable elution strength ) result in a number of consequences that (i) produce significant differences compared to HPLC with classical liquids and (ii) procure several advantages in terms of speed, column efficiency , and versatility. The major features of packed column SFC are presented, together with instrumental details. Finally, selected applications related to achiral and chiral analysis are presented, while the last section focuses on preparative‐scale separations.
Instrumentation for Sub‐ and Supercritical Fluid Chromatography
Authors: Khayamian Taghi , Daneshfar Ali , Ghaziaskar Hassan 
Published: November 2015

Abstract

This chapter describes an overview of the instrumentation in supercritical fluid chromatography (
SCF
) and its application in different fields of science and industry. The main components of an
SCF
instrument including mobile phase , pump, injector, column, restrictor, and detector are explained. Recent trends in the modification of these parts are also discussed. Finally, the application of
SFC
to separate a wide variety of materials, such as food constituents, drugs, biological samples, and natural products, is summarized.
Capillary Electromigration Techniques: Capillary Electrophoresis
Authors: Kašička Václav 
Published: November 2015

AbstractThis chapter provides a brief introduction to capillary electrophoresis (CE) – a modern high‐performance electromigration separation method. First, basic concepts of electrophoresis in general, such as ionic, effective and limiting electrophoretic mobilities, their concentration, and pH dependencies are presented, and the concomitant electrokinetic phenomenon – electroosmotic flow – is introduced. Second, the separation principle and the basic experimental setup ofCEare shown and the advantages and limitations ofCEas compared to other separation methods, especially liquid chromatography and slab gel electrophoresis, are reported. Further, the dispersion effects inCEand the ways of minimization of their detrimental effects on the separation efficiency ofCEare described. Finally, the high application potential ofCEfor highly sensitive qualitative and quantitative analysis, microscale isolation, and physicochemical and biochemical characterization of a large spectrum of all types of ionogenic compounds and (bio)particles is emphasized. For more detailed studies ofCEand other capillary electromigration methods, many literature references are given.
Capillary Gel Electrophoresis
Authors: Kerékgyártó Márta , Guttman András 
Published: November 2015

AbstractCapillary gel electrophoresis is a rapidly developing technique, which has been successfully used in the bioanalytical field, especially for separation of biopolymers like nucleic acids, proteins, and complex carbohydrates. This chapter starts with a summary of the theoretical and practical aspects of capillary gel electrophoresis including separation principles, instrument design, capillary coating techniques, and the most frequently used sieving matrices. It is followed by the description of the various detection options, such asUV‐Vis, diode‐array, laser‐induced fluorescence, and light‐emitting diode‐induced fluorescence types. Finally, an overview of the key application areas is given with the main emphasis on nucleic acid, protein, and complex carbohydrate analysis, as well as the latest developments in microchip electrophoresis devices.
Nonaqueous Capillary Electrophoresis
Authors: Schappler Julie , Rudaz Serge 
Published: November 2015

Abstract

The level of differential migration between analytes defines the selectivity achievable, while band dispersion occurs as the analytes migrate through the CE system. This chapter considers both aspects in the context of nonaqueous capillary electrophoresis (NACE). One section is dedicated to selectivity aspects and another devoted to efficiency. The operational conditions, including the composition of the BGE and the sample solvents that should be used for best performance in NACE, are also discussed. A dedicated section is addressed to the coupling of NACE with mass spectrometry (MS), which is now considered the gold standard detection method for numerous applications. NACE electrolytes may generate low electric current and low Joule heating, enabling the use of short capillaries (rapid analyses), wide‐bore capillaries with internal diameters (ID) >50 m (sensitivity enhancement), high voltages (rapid analyses and efficiency improvement), and MS detection (sensitivity and selectivity enhancement).
Targeted and Non‐Targeted Analysis
Authors: Rodriguez‐Saona Luis E. , Pujolras Marçal Plans , Giusti M. Monica 
Published: November 2015

AbstractThis chapter discusses analyte screening methods based on targeted and nontargeted approaches using three of the most well‐known analytical techniques: optical methods, chromatography, and infrared spectroscopy. The sections of the chapter are defined by each of the screening methods. Our main objective is to describe the systematic analysis of compounds in complex matrices and present some general advantages and challenges of the different techniques. The fundamentals of each screening method are presented in the general introduction, and as the chapter advances, deeper concepts and new technology are presented. This chapter is based on current literature on the topic combined with the teaching experience of decades, interacting with students and industry professionals. Real examples are presented to show some of the solutions to resolve screening methods problems. Finally, multivariate statistical techniques are also introduced to aid in the use of the new generation of analytical instruments producing large data matrices, and approaches to extract relevant information from the acquired data limiting the effects of high correlation and nondefined matrices are discussed.
Conventional Extraction Techniques:Soxhlet and Liquid–Liquid Extractions and Evaporation
Authors: Daso Adegbenro Peter , Okonkwo Okechukwu Jonathan 
Published: November 2015

AbstractThis chapter presents a general overview of the traditional extraction techniques commonly applied to both solid and liquid matrices are evaluated with a view to emphasize their sustained significance in a rapidly changing analytical chemistry discipline as evidenced with the introduction of newer and more sophisticated extraction techniques. For this purpose, the conventional Soxhlet extraction technique for solid matrices and the traditional liquid‐liquid extraction techniques for liquid matrices are critically evaluated. The use of evaporation as a traditional method for extraction and/or separation of target analytes are also considered to further bolster the relevance of this technique in modern analytical chemistry studies. Besides the conventional sample extraction techniques such as Soxhlet extraction (SE), liquid‐liquid extraction (LLE), and mechanical shaking, newer and more sophisticated techniques such as microwave‐assisted extraction (MAE), accelerated solvent extraction (ASE), also known as pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE), have been developed.
Liquid‐Phase Microextraction
Authors: Ganjali Mohammad Reza , Rezapour Morteza , Norouzi Parviz , Faridbod Farnoush 
Published: November 2015

Abstract

The chapter provides the reader with a detailed introduction to the different classes of the burgeoning technique of liquid–liquid microextraction. It starts with an introduction to the method and its subclasses and further develops into three distinct sections of single‐drop microextraction (
SDME
), hollow fiber liquid‐phase microextraction (
HFLPME
), and dispersive liquid–liquid microextraction and describes each class and its derivative methods. Since the configurations of the methods are of importance, figures showing the necessary setups are included in each case in addition to the explanation of the history of the methods and their advantages and shortcomings. The focus of the chapter is more on the major practical considerations to be noted while using each of the techniques described, and leaves the case‐based details of the numerous studies performed in each area out for the purpose of giving the reader an overview of this area that can be found in the publications on each.
Environmental Applications of Solid Phase Microextraction Techniques
Authors: Montesdeoca‐Esponda Sarah , Torres‐Padrón M Esther , Sosa‐Ferrera Zoraida , Santana‐Rodríguez José Juan 
Published: November 2015

Abstract

Miniaturization is a strategy employed in sample preparation that has gained much prominence in recent years due to the need to develop more efficient procedures that consume less solvent and time. The analysis of important families of contaminants, such as pesticides or polycyclic aromatic hydrocarbons (
PAH
s), in liquid samples has traditionally been conducted using conventional techniques, such as liquid–liquid extraction (
LLE
) and solid‐phase extraction (
SPE
). Although
SPE
uses much less amount of solvent than
LLE
, the volume can still be significant, making both techniques expensive and environment‐unfriendly procedures. The miniaturization of sample preparation processes has led to a new generation of techniques with improved characteristics. Different solid‐phase microextraction (
SPME
) techniques, including fibers, stir bar sorptive extraction (
SBSE
) and thin‐film microextraction (
TFME
), and automated techniques, such as in‐tube solid‐phase microextraction (
IT
‐
SPME
), have allowed the determination of different families of contaminant compounds, including emerging compounds in complex environmental waters, such as seawater, groundwater, or superficial water.

The emerging compounds are relatively unknown compounds that are not covered by the existing regulations; they are frequently detected in different environmental compartments in very low concentrations. For this reason, their analysis requires extraction, purification and preconcentration from the matrix and subsequent separation and detection systems that can measure these concentration levels.

In this chapter, we review the most recent applications of microextraction techniques based on solid phase coupled to liquid chromatography (
LC
) for the determination of different emerging contaminants in several water environmental matrices.
The Effects of Communicative Source and Dynamics on the Maintenance and Accessibility of Longer‐term Memories: Applications to Sexual Abuse and Its Public Disclosure
Authors: Fagin Martin M. , Cyr Travis G. , Hirst William 
Published: November 2015

SummaryRecent public testimony concerning sexual abuse on the part of celebrities raises the question of what happens to memories when they enter the public domain. The present paper reviews research on the effects of communication on memory and examines how the context of this communication affects its influence on memory, both in the short and long term. Specifically, we discuss how communication with the self, a small group, and the larger public affects the content and availability of different elements of both emotional and more mundane memories, in the short term and in the long term. Evidence suggests that, although forgetting is rapid in the first few years, it then levels off. Although this pattern would suggest that the effects conversational influences have on memory may be limited to the first few years, the present paper argues that the pattern will vary as the source changes.Copyright © 2015 John Wiley & Sons, Ltd.
Investigating the Effect of Treated Rice Straw in PLLA/Starch Composite: Mechanical, Thermal, Rheological, and Morphological Study
Authors: Davachi Seyed Mohammad , Bakhtiari Saeed , Pouresmaeel‐Selakjani Peyman , Mohammadi‐Rovshandeh Jamshid , Kaffashi Babak , Davoodi Saeed , Yousefi Ardavan 
Published: November 2015

ABSTRACTThe aim of this work is to use lignocellulosic wastes as low price additives in biodegradable polymers. The rice straw (RS) was treated by means of different methods, and then it was introduced to the poly(lactic acid)/starch composites. The effects of different treatments on RS properties were investigated using the Fourier transform infrared, tensile, charpy, hardness, differential scanning calorimetry, rheology, contact angle, and scanning electron microscopy. It was found that 5–10% of all the differently treated RS increases the overall properties. Moreover, silica and lignin were mainly affected by such treatments; however, a balance between silica and lignin shows the best results. The modified alkali‐treated rice straw (ARS treatment) prevented cellulose from degradation by creating a balance between silica and lignin, which controls the opposing effects of lignin including paste‐like and plasticating effects. Finally, the ARS‐filled samples show improved overall properties among the other samples. The obtained composites with optimum filler content may be used in the biomembranes and food packaging applications.
Dative Wechselwirkungen einer Bor‐zentrierten Lewis‐Base mit Gruppe‐13‐Elementen
Authors: Braunschweig Holger , Dewhurst Rian D. , Pentecost Leanne , Radacki Krzysztof , Vargas Alfredo , Ye Qing 
Published: November 2015

AbstractDie Verwendung einer elektronenreichen, monovalenten Borspezies erlaubt die Bildung von Addukten mit Gruppe‐13‐Lewis‐Säuren, wobei sowohl Bor als auch Stickstoff als Donorzentrum dienen können. Während die harte Lewis‐Säure AlCl3 an ein Stickstoffatom der Lewis‐Base koordiniert, binden die weicheren Lewis‐Säuren GaX3 (Cl, Br, I) an das Borzentrum. Mit Letzteren werden hierbei erstmalig Lewis‐Addukte zwischen einer Bor‐zentrierten Lewis‐Base und einer Hauptgruppenelement‐Lewis‐Säure ohne Cluster‐artiges Strukturmotiv gebildet.
Structurally Defined Molecular Hypervalent Iodine Catalysts for Intermolecular Enantioselective Reactions
Authors: Haubenreisser Stefan , Wöste Thorsten H. , Martínez Claudio , Ishihara Kazuaki , Muñiz Kilian 
Published: November 2015

AbstractMolecular structures of the most prominent chiral non‐racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen‐bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis.
One‐Step Pyrolysis Preparation of 1.1.1 Oriented Gold Nanoplatelets Supported on Graphene and Six Orders of Magnitude Enhancement of the Resulting Catalytic Activity
Authors: Primo Ana , Esteve‐Adell Ivan , Coman Simona N. , Candu Natalia , Parvulescu Vasile I. , Garcia Hermenegildo 
Published: November 2015

AbstractPyrolysis of chitosan films containing Au3+ renders 1.1.1 oriented Au nanoplatelets (20 nm lateral size, 3–4 nm height) on a few layers of N‐doped graphene (${\overline {{\rm{Au}}} }$/fl‐G), while the lateral sides were 0.0.1 oriented. Comparison of the catalytic activity of ${\overline {{\rm{Au}}} }$/fl‐G films with powders of unoriented Au NPs supported on graphene showed that ${\overline {{\rm{Au}}} }$/fl‐G films exhibit six orders of magnitude enhancement for three gold‐catalyzed reactions, namely, Ullmann‐like homocoupling, CN cross coupling, and the oxidative coupling of benzene to benzoic acid. This enhancement is the result of the defined morphology, facet orientation of Au nanocrystals, and strong gold‐graphene interaction.
In situ polymerization of polyurethane‐silver nanocomposite foams with intact thermal stability, improved mechanical performance, and induced antimicrobial properties
Authors: Madkour Tarek M. , Abdelazeem Eman A. , Tayel Amr , Mustafa Ghada , Siam Rania 
Published: November 2015

ABSTRACTSilver nanoparticle‐reinforced thermoplastic polyurethane (PU/AgNP) nanocomposite foams were prepared using in situ polymerization techniques in accordance with DOW chemicals’ industrial standards. The foams exhibited improved mechanical performance, induced antimicrobial properties, and intact stability when subjected to a thermal degradation treatment. Scanning electron microscopy (SEM) indicated a homogeneous dispersion of the silver nanoparticle (AgNP) within the polymeric matrix at low filler loadings and a cluster formation at higher loadings. SEM also indicated the agglomeration of the silver nanofiller particles as a result of the thermal degradation treatment, which caused them to lose their nanoscopic characteristics and act as ordinary silver metal. Molecular modeling techniques were used to explain these observations and confirmed the higher repulsive interactions between the polymer chains and the silver nanoparticles with the increase in the nanofiller content. Stress relaxation of the nanocomposites showed optimum mechanical performance and lowest hysteresis for the 0.1% AgNP nanocomposites due to the confinement of the PU chains between the large number of the nanoparticles. Incubation with 0.1% foam inhibited the growth of Klebseilla spp. and Escherichia coli and to some extent Staphylococcus spp. This is very interesting as the same nanocomposite loaded with 0.1% AgNp has also shown the best mechanical performance highlighting the strong action of this “unclustered” low concentration on both the material and biomedical sides. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43125.
Millimeter‐size polyethylene hollow spheres synthesized with MgCl2‐supportedZiegler‐Natta catalyst
Authors: Qi Meizhou , Zhang Biao , Fu Zhisheng , Xu Junting , Fan Zhiqiang 
Published: November 2015

ABSTRACTPolyethylene hollow spheres with diameters of 0.4–2 mm were synthesized by a two‐step slurry polymerization in a single reactor with a spherical MgCl2‐supported Ziegler‐Natta catalyst activated by triethylaluminum, in which the first step was prepolymerization with 0.1 MPa propylene and the second step was ethylene polymerization under 0.6 MPa. The prepolymerization step was found necessary for the formation of hollow spherical particles with regular shape (perfectly spherical shape). The effects of adding small amount of propylene (propylene/ethylene < 0.1 mol/mol) in the reactor after the prepolymerization step were investigated. Average size of the polymer particles was increased, and the polymerization rate was markedly enhanced by the added propylene. Development of the particle morphology with polymerization time was also studied. The polymer particles formed by less than 20 min of ethylene polymerization showed hollow spherical morphology with thin shell layer. Most of the particles had ratio of shell thickness/particle radius smaller than 0.5. By prolonging the ethylene polymerization, the shell thickness/particle radius ratio gradually approached 1, and the central void tended to disappear. Central void in polymer particles formed from smaller catalyst particles disappeared after shorter time of polymerization than those formed from bigger catalyst particles. The shell layer of the hollow particles contained large number of macro‐, meso‐ and micro‐pores. The mesopore size distributions of four typical samples were analyzed by nitrogen adsorption–desorption experiments. A simplified multigrain model was proposed to explain the morphogenesis of the hollow spherical particles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43207.
Effects and Mechanism of Action of Inducible Nitric Oxide Synthase on Apoptosis in a Rat Model of Cerebral Ischemia‐Reperfusion Injury
Authors: Zheng Li , Ding Junli , Wang Jianwei , Zhou Changman , Zhang Weiguang 
Published: November 2015

ABSTRACTInducible nitric oxide synthase (iNOS) is a key enzyme in regulating nitric oxide (NO) synthesis under stress, and NO has varying ability to regulate apoptosis. The aim of this study was to investigate the effects and possible mechanism of action of iNOS on neuronal apoptosis in a rat model of cerebral focal ischemia and reperfusion injury in rats treated with S‐methylisothiourea sulfate (SMT), a high‐selective inhibitor of iNOS. Seventy‐two male Sprague‐Dawley (SD) rats were randomly divided into three groups: the sham, middle cerebral artery occlusion (MCAO) + vehicle, and MCAO + SMT groups. Neurobehavioral deficits, infarct zone size, and cortical neuron morphology were evaluated through the modified Garcia scores, 2,3,5‐triphenyltetrazolium chloride (TTC), and Nissl staining, respectively. Brain tissues and serum samples were collected at 72 hr post‐reperfusion for immunohistochemical analysis, Western blotting, Terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin Nick End Labeling assay (TUNEL) staining, and enzyme assays. The study found that inhibition of iNOS significantly attenuated the severity of the pathological changes observed as a result of ischemia‐reperfusion injury: SMT reduced NO content as well as total nitric oxide synthase (tNOS) and iNOS activities in both ischemic cerebral hemisphere and serum, improved neurobehavioral scores, reduced mortality, reduced the infarct volume ratio, attenuated morphological changes in cortical neurons, decreased the rate of apoptosis (TUNEL and caspase‐3‐positive), and increased phospho (p)‐AKT expression in ischemic penumbra. These results suggested that inhibition of iNOS might reduce the severity of ischemia‐reperfusion injury by inhibiting neuronal apoptosis via maintaining p‐AKT activity. Anat Rec, 299:246–255, 2016. © 2015 Wiley Periodicals, Inc.