bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Advances in Column Technology
Authors: Shalliker Ross Andrew , Kocic Danijela
Published: November 2015

Over the past half century, there has been a substantial development in the modern chromatography column. Particle sizes have decreased from 10 to now sub‐2 μm, and with it the number of theoretical plates has increased to about 200 000 per meter on fully porous particles, and 250 000 plates per meter for core–shell particles.

Despite this change, the number of plates used per separation has not changed that much, since shorter columns must be used when packed with the smaller particles because a great deal more pressure is required to drive mobile phase through the column. One significant change, however, is that separations have got faster as a result of the decrease in particle size.

Nevertheless, over time, one fundamental problem still exists; packed beds are heterogeneous, and this is a source of performance loss. To overcome the consequences of packing heterogeneity, a new column technology has been developed, which is called active flow technology (
AFT
). This technology minimizes the significance of the wall effect and provides much greater separation efficiency, while enabling faster separations, especially when coupled to MS detection. This chapter highlights the causes of column bed heterogeneity and presents active flow technology columns, illustrating briefly some of the new directions that the development of this column technology can take.
Reversed Phase Liquid Chromatography
Authors: García‐Alvarez‐Coque Maria C. , Baeza‐Baeza Juan J. , Ramis‐Ramos Guillermo
Published: November 2015

Reversed phase liquid chromatography (RPLC) is a mode of high‐performance liquid chromatography (HPLC) that employs a nonpolar stationary phase (most frequently a hydrocarbon chain chemically bonded to porous silica particles) and a polar mobile phase constituted by water and at least a water‐miscible organic solvent, which performs as a modifier.RPLCis a mature technique, employed in science and technology by chemists, biochemists, and pharmacists for analysis and purification. Applications cover environmental control, food, clinical, pharmaceutical, and industrial analyses, drug and chemical manufacturing (at both quality control and preparative scales), biomedical studies, and measurement of physicochemical properties. The development ofRPLChas been based primarily on empirical observations. The diversity of retention mechanisms has received considerable attention, sometimes with conflicting results. This reflects the difficulty in understanding the underlying principles. In this chapter, the theoretical background and technical traits ofRPLCare outlined. The factors that contribute to the separation are described, together with the main approaches proposed to understand the observed behaviors. The advantages and limitations of using either isocratic or gradient elution are discussed. A picture of the retention behavior at the molecular level, including a description of the dewetting effect of highly aqueous mobile phases, is also given. The trends in the current evolution of the technique are commented upon. The overview contains over 100 references.
Normal‐Phase and Polar Organic Solvents Chromatography
Authors: Younes Ahmed A. , Galea Charlene , Mangelings Debby , Vander Heyden Y.
Published: November 2015

This chapter starts with a brief overview of chromatography and focuses on liquid chromatography, particularly
NPLC
and
POSC
. Retention mechanisms both for polarity‐based separations seen in
NPLC
and
POSC
and for charge and size‐based separations are explained. The second part of the chapter focuses on different stationary and mobile phases that can be combined together to give a chromatographic system with an acceptable separation and required selectivity. Factors that should be kept in mind when switching from one stationary or mobile phase to another are highlighted and examples that facilitate understanding are used.
Chiral Separation of Some Classes of Pesticides by
HPLC
Method
Authors: Ali Imran , Hussain Iqbal , Sanagi Mohd Marsin , Aboul‐Enein Hassan Y.
Published: November 2015

About 28% of pesticides are chiral, and simple analyses of pesticides are creating confusion due to the fact that one of the enantiomers is toxic to pests, while the other is a burden for the environment. Moreover, different toxicities of the enantiomers confuse farmers when they measure the dose lethal for pests. Therefore, chiral analysis is an important issue for chemical, agrochemical, and chemical industries. Attempts have been made to describe state‐of‐the‐art methods of chiral analysis of pesticides by
HPLC
using various types of chiral columns, eluents, and other
HPLC
conditions along with the chiral recognition mechanisms involved in chiral separation using different chiral stationary phases (
CSPs
).
Gas Chromatography: Theory and Thermodynamics, and Selectivity
Authors: Spangler Glenn E.
Published: November 2015

After a brief historical introduction to gas chromatography, the principles of operation are explained. Following a brief discussion of the earlier retention time and plate theories, a more advanced continuum theory is systematically developed with liberal cross‐referencing to the open scientific literature. The chromatogram for methanol injected into a Rtx‐5 (5% diphenyl/95% dimethyl polysiloxane) column coupled to an injector and detector is modeled and nomenclature established for its description. Finally, issues related to sensitivity, resolution, and temperature programming are discussed.
Overview of Detectors in Gas Chromatography
Authors: Rahman Md. Musfiqur , El‐Aty A.M. Abd , Shim Jae‐Han
Published: November 2015

The aim of this chapter is to provide basic interpretation of gas chromatography (
GC
) detectors mainly devoted to the students and beginners in the field of
GC
.
Current Use of Gas Chromatography and Applications
Authors: Vetter Walter
Published: November 2015

Over the past 60 years, gas chromatography (GC) has been developed into the most powerful separation technique for volatile compounds. This chapter describes milestones in this success story, classic and recent developments in modern instrumentation ofGC, current applications and trends as well as future perspectives, and how they fit together. Sections discuss novel stationary phases, comprehensiveGC,GCdetectors, the referencing ofGCdata as well as instrumental miniaturization, applications in the analysis of fatty acids, flavor compounds, pollutants and drugs as well as special sections on direct enantiomer separations using modified cyclodextrins, inverse gas chromatography, and microgas chromatographic separations.
Gas Chromatography with Mass Spectrometry (GC‐MS)
Authors: Vetter Walter
Published: November 2015

The 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

Sub‐ 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

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

This 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

Capillary 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

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

This 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

This 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

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

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

Recent 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.
A Cross‐Linkable Donor Polymer as the Underlying Layer to Tune the Active Layer Morphology of Polymer Solar Cells
Authors: Meng Bin , Wang Zaiyu , Ma Wei , Xie Zhiyuan , Liu Jun , Wang Lixiang
Published: November 2015

For polymer solar cells (PSCs) with conventional configuration, the vertical composition profile of donor:acceptor in active layer is detrimental for charge carrier transporting/collection and leads to decreased device performance. A cross‐linkable donor polymer as the underlying morphology‐inducing layer (MIL) to tune the vertical composition distribution of donor:acceptor in the active layer for improved PSC device performance is reported. With poly(thieno[3,4‐b]‐thiophene/benzodithiophene):[6,6]‐phenyl C71‐butyric acid methyl ester (PTB7:PC71BM) as the active layer, the MIL material, PTB7‐TV, is developed by attaching cross‐linkable vinyl groups to the side chain of PTB7. PSC device with PTB7‐TV layer exhibits a power conversion efficiency (PCE) of 8.55% and short‐circuit current density (JSC) of 15.75 mA cm−2, in comparison to PCE of 7.41% and JSC of 13.73 mA cm−2 of the controlled device. The enhanced device performance is ascribed to the much improved vertical composition profile and reduced phase separation domain size in the active layer. These results demonstrate that cross‐linked MIL is an effective strategy to improve photovoltaic performance of conventional PSC devices.
Gallium‐Loaded Dissolvable Microfilm Constructs that Provide Sustained Release of Ga3+ for Management of Biofilms
Authors: Herron Maggie , Schurr Michael J. , Murphy Christopher J. , McAnulty Jonathan F. , Czuprynski Charles J. , Abbott Nicholas L.
Published: November 2015

The persistence of bacterial biofilms in chronic wounds delays wound healing. Although Ga3+ can inhibit or kill biofilms, precipitation as Ga(OH)3 has prevented its use as a topical wound treatment. The design of a microfilm construct comprising a polyelectrolyte film that releases noncytotoxic concentrations of Ga3+ over 20 d and a dissolvable micrometer‐thick film of polyvinylalcohol that enables facile transfer onto biomedically important surfaces is reported. By using infrared spectroscopy, it is shown that the density of free carboxylate/carboxylic acid and amine groups within the polyelectrolyte film regulates the capacity of the construct to be loaded with Ga3+ and that the density of covalent cross‐links introduced into the polyelectrolyte film (amide‐bonds) controls the release rate of Ga3+. Following transfer onto the wound‐contact surface of a biologic wound dressing, an optimized construct is demonstrated to release ≈0.7 μg cm−2 d−1 of Ga3+ over 3 weeks, thus continuously replacing Ga3+ lost to precipitation. The optimized construct inhibits formation of P. aeruginosa (two strains; ATCC 27853 and PA01) biofilms for up to 4 d and causes pre‐existing biofilms to disperse. Overall, this study provides designs of polymeric constructs that permit facile modification of the wound‐contacting surfaces of dressings and biomaterials to manage biofilms.
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

The 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.
What next in fundamental physics in space
Authors: Battiston R.
Published: November 2015

With the discovery of the Higgs boson the SM is complete and we are looking for the remaining 95% of the universe. Astroparticle physics carries promises to deliver some answers to this basic question. In this paper I try to explain why.
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

Die 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

Molecular 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

Pyrolysis 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

Silver 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

Polyethylene 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

Inducible 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.
Intestinal Rotation and Physiological Umbilical Herniation During the Embryonic Period
Authors: Ueda Yui , Yamada Shigehito , Uwabe Chigako , Kose Katsumi , Takakuwa Tetsuya
Published: November 2015

Drastic changes occur during the formation of the intestinal loop (IL), including elongation, physiological umbilical herniation (PUH), and midgut rotation. Fifty‐four sets of magnetic resonance images of embryos between Carnegie stage (CS) 14 and CS 23 were used to reconstruct embryonic digestive tract in three dimensions in the Amira program. Elongation, PUH, and rotation were quantified in relation to the proximal part of the superior mesenteric artery (SMA), designated as the origin. Up to CS 16, IL rotation was initially observed as a slight deviation of the duodenum and colorectum from the median plane. The PUH was noticeable after CS 17. At CS 18, the IL showed a hairpin‐like structure, with the SMA running parallel to the straight part and the cecum located to the left. After CS 19, the IL began to form a complex structure as a result of the rapid growth of the small intestinal portion. By CS 20, the IL starting point had moved from the right cranial region to an area caudal to the origin, though elongation of the duodenum was not conspicuous—this was a change of almost 180° in position. The end of the IL remained in roughly the same place, to the left of and caudal to the origin. Notably, the IL rotated around the origin only during earlier stages and gradually moved away, running transversely after CS 19. The movements of the IL may be explained as the result of differential growth, suggesting that IL rotation is passive. Anat Rec, 299:197–206, 2016. © 2015 Wiley Periodicals, Inc.
Gestational surrogacy and the role of routine embryo screening: Current challenges and future directions for preimplantation genetic testing
Authors: Sills E. Scott , Anderson Robert E. , McCaffrey Mary , Li Xiang , Arrach Nabil , Wood Samuel H.
Published: November 2015

Preimplantation genetic screening (PGS) is a component of IVF entailing selection of an embryo for transfer on the basis of chromosomal normalcy. If PGS were integrated with single embryo transfer (SET) in a surrogacy setting, this approach could improve pregnancy rates, minimize miscarriage risk, and limit multiple gestations. Even without PGS, pregnancy rates for IVF surrogacy cases are generally satisfactory, especially when treatment utilizes embryos derived from young oocytes and transferred to a healthy surrogate. However, there could be a more general role for PGS in surrogacy, since background aneuploidy in embryos remains a major factor driving implantation failure and miscarriage for all infertility patients. At present, the proportion of IVF cases involving GS is limited, while the number of IVF patients requesting PGS appears to be increasing. In this report, the relevance of PGS for surrogacy in the rapidly changing field of assisted fertility medicine is discussed. Birth Defects Research (Part C) 108:98–102, 2016. © 2015 Wiley Periodicals, Inc.
Participatory Action Research with Filipino Street Youth: Their Voice and Action against Corporal Punishment
Authors: Wartenweiler Daniel , Mansukhani Roseann
Published: November 2015

The study investigated perspectives on corporal punishment of adolescents from street families in Manila, with the aim of creating actions that address the issue in that specific context. Participatory action research (PAR) was employed as a research design, collecting qualitative data with 11 youth, selected through purposive sampling. Results showed that harsh corporal punishment is highly normative in that context, most frequently physically and emotionally abusive, and often co‐occurs with verbal abuse. It has negative effects on the youth's feelings towards, and their relationship with, their parents, and it leads to defiant behaviours. The youth planned an action project to address the issue of corporal punishment in their families: producing a video clip and holding a parents' meeting. Through the PAR process, the youth were empowered to voice their feelings and perceptions and to take action to address the issue of corporal punishment in their families and in the wider community. The study demonstrated how PAR can serve as a pathway towards empowerment for a very vulnerable group.

‘Investigated perspectives on corporal punishment of adolescents from street families in Manila’

Key Practitioner Messages:

Little is known about children's perceptions related to corporal punishment, and children remain powerless to address this issue which most often happens in the intimate family context.

Harsh corporal punishment is a highly normative experience for street youth in Manila, and is often physically and verbally abusive.

The PAR process served as a pathway to empowerment for the youth, enabling them to address the issue of corporal punishment in their context.

‘Little is known about children's perceptions related to corporal punishment’
Highly Efficient Hybrid Cobalt–Copper–Aluminum Layered Double Hydroxide/Graphene Nanocomposites as Catalysts for the Oxidation of Alkylaromatics
Authors: Xie Renfeng , Fan Guoli , Yang Lan , Li Feng
Published: November 2015

The selective oxidation of alkylaromatics is of vital importance for the production of high‐added‐value raw materials. The development of highly efficient heterogeneous catalytic oxidation systems under mild conditions has become an attractive research area. In this work, hybrid Co–Cu–Al layered double hydroxide/graphene (CoCuAl‐LDH/graphene) nanocomposites, which were assembled successfully by a one‐step coprecipitation route without the use of any additional reducing agents, were used as highly efficient catalysts for the liquid‐phase selective oxidation of ethylbenzene using tert‐butyl hydroperoxide as the oxidant. A series of characterizations revealed that graphene could stabilize CoCuAl‐LDH nanoplatelets effectively in the nanocomposites, and in turn, highly dispersed CoCuAl‐LDH could prevent the aggregation of the graphene nanosheets. By fine‐tuning the mass ratio of graphene to CoCuAl‐LDH, such nanocomposites offered a tunable catalytic oxidation performance. In particular, the nanocomposite with the graphene/CoCuAl‐LDH mass ratio of 0.4:1 exhibited a remarkable catalytic performance with a considerable conversion (96.8 %) and selectivity to acetophenone (>95.0 %), which was mainly attributed to the synergism between the active CoCuAl‐LDH component and the graphene matrix in the unique hetero‐nanostructure. Moreover, the as‐assembled nanocomposite catalysts displayed good recyclability and were active for the selective oxidation of other alkylaromatics.
Numerical Simulation of the Arrangement of Baffles on Radiation Distribution and Disinfection in UV Reactors
Authors: Cao Haochen , Deng Baoqing , Hong Jie , Xue Jiao , Chang Fei
Published: November 2015

The optimization of installation of baffles in a UV rector is investigated. The flow field is obtained by solving continuity and momentum equations. The radiation intensity is solved by a radiative transfer equation. The UV dosage is obtained by coupling the Lagrangian particle tracking approach with the solved radiation intensity. One unbaffled reactor and two baffled reactors are simulated. The baffled UV reactor A has the longest residence time and the lowest UV dosage while the baffled UV reactor B has the relatively longer residence time and the highest UV dosage. The unbaffled reactor performs between the two baffled reactors considering residence time and UV dosage. The baffled UV reactor B enables the best disinfection of microorganisms. The results demonstrate that optimization should consider flow field and radiation intensity simultaneously.
Contaminant‐Degrading Microorganisms Identified Using Stable Isotope Probing
Authors: Cupples Alison M.
Published: November 2015

Stable isotope probing (SIP) enables function to be linked with identity without isolating the microorganisms responsible. This culture‐independent approach has been adapted to identify the microorganisms involved in the degradation of numerous environmental contaminants. SIP studies have been performed in situ or in laboratory microcosms inoculated with soil, sediment, groundwater or bioreactor samples. This review focuses on the microorganisms that have been identified in those projects. SIP studies involving the degradation of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, gasoline‐associated contaminants, chlorinated solvents, hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), phenol, uranium, and pentachlorophenol are discussed. The significant diversity of contaminant‐degrading microorganisms is highlighted.
Non‐Oxidative Dehydrogenation Pathways for the Conversion of C2–C4 Alcohols to Carbonyl Compounds
Authors: Shylesh Sankaranarayanapillai , Kim Daeyoup , Ho Christopher R. , Johnson Gregory R. , Wu Jason , Bell Alexis T.
Published: November 2015

Invited for this month′s cover is the group of Alexis T. Bell at The University of California, Berkeley in Berkeley, California. The image shows the utility of gold nanoparticles deposited on hydrotalcite (Au/HT) for the continuous gas‐phase non‐ oxidative dehydrogenation reaction of bioderived C2–C4 alcohols to the respective carbonyl compounds and hydrogen. The Communication itself is available at 10.1002/cssc.201500786.
A 4.8–6.8 GHz low phase noise LC VCO in 0.13‐µm CMOS technology
Authors: Wang Yuan , Gan Shanliang , Jia Song , Zhang Xing
Published: November 2015

This letter presents a novel LC voltage controlled oscillator (VCO) supporting the high‐speed serial transmission standard of RapidIO in 0.13‐µm complementary metal‐oxide semiconductor technology. The low phase noise is achieved through several techniques including current source switching, parallel coupled negative transconductance cell, and varactor bias combination scheme. Measured results of proposed circuit show a low phase noise of −120 dBc/Hz at 1 MHz offset from 6.25 GHz carrier and tuning range of 4.8 ~ 6.8 GHz (34.48%) while consuming 7.4 mW under the supply voltage of 1.2 V. Copyright © 2015 John Wiley & Sons, Ltd.
FGF signaling enhances a sonic hedgehog negative feedback loop at the initiation of spinal cord ventral patterning
Authors: Morales Aixa V. , Espeso‐Gil Sergio , Ocaña Inmaculada , Nieto‐Lopez Francisco , Calleja Elena , Bovolenta Paola , Lewandoski Mark , Diez del Corral Ruth
Published: November 2015

A prevalent developmental mechanism for the assignment of cell identities is the production of spatiotemporal concentration gradients of extracellular signaling molecules that are interpreted by the responding cells. One of such signaling systems is the Shh gradient that controls neuronal subtype identity in the ventral spinal cord. Using loss and gain of function approaches in chick and mouse embryos, we show here that the fibroblast growth factor (FGF) signaling pathway is required to restrict the domains of ventral gene expression as neuroepithelial cells become exposed to Shh during caudal extension of the embryo. FGF signaling activates the expression of the Shh receptor and negative pathway regulator Patched 2 (Ptch2) and therefore can enhance a negative feedback loop that restrains the activity of the pathway. Thus, we identify one of the mechanisms by which FGF signaling acts as a modulator of the onset of Shh signaling activity in the context of coordination of ventral patterning and caudal axis extension. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 956–971, 2016
Increase in antioxidant activity of brined olives (Carolea cv.) thermally treated in different packaging types
Authors: Amalia Piscopo , Alessandra De Bruno , Angela Zappia , Marco Poiana
Published: November 2015

This work was aimed to study the effect of a thermal processing on brined olives (and their covering liquids) packaged in different types of containers (glass jar with two volumes and plastic pouches made of two materials). The results show an increase of antioxidant activity of all pasteurized olives because of the melanoidin formation in pulp after processing with no differences among materials and sizes of packaging. In this study, glass packaging involved lower depletion of total polyphenol content and better preservation of the α‐tocopherol content in olive pulp than plastic pouches during the processing. The olives packaged in PA/PE showed higher content of antioxidant compounds than the olives processed in OPA/PP pouches.

Practical application: Practical application for the study entitled “Increase in antioxidant activity of brined olives (Carolea cv.) thermally treated in different packaging types” regards the study of chemical changes on olives in different containers. Therefore in food industry the positive effect of heat and the right packaging form could be useful for preservation of olives and also enhancing of their functional properties. The results of this work showed an increased antioxidant activity in brined olives thermally treated, due to the melanoidin formation.

Increase in antioxidant activity of table olives after pasteurization in different packaging types. B (Brined olives); P1 (Olives pasteurized in 370 mL‐glass jars); P2 (Olives pasteurized in 580 mL‐glass jars); P3 (Olives pasteurized in 450 mL‐PA/PE pouches); P4 (Olives pasteurized in 450 mL‐OPA/PP pouches).
A Computational Study of the Intramolec­ular Carbolithiation of Aryllithiums: Solvent and Substituent Effects
Authors: Mattalia Jean‐Marc , Nava Paola
Published: November 2015

The intramolecular carbolithiation of olefinic aryllithiums provides an interesting route to functionalized carbo‐ and heterocyclic systems. We have computed mechanistic energy profiles (DFT) by varying the nature of the solvent and aryllithium. Our calculations suggest that the solvent mainly impacts the aggregation state of the aryllithium intermediates rather than activates the reactive species themselves. Further investigations revealed that substitution of the terminal position of the double bond and the N‐allyl side‐chain strongly influence the energy barriers, in good agreement with experimental data.