bluuebunny/crossref_metadata_2025 huggingface dataset:
Multivariate Analysis: Overview
Authors: Krzanowski Wojtek J.
Published: September 2014

Multivariate analysis is appropriate whenever more than one variable is measured on each sample individual, and overall conclusions about the whole system are sought. Many different multivariate techniques now exist for addressing a variety of objectives. This brief review outlines, in broad terms, some of the more common objectives and sketches out some of the ways in which they are tackled. The techniques are grouped under four headings: visualization and description, extrapolation and inference, discrimination and classification, modeling and explanation. Within each heading, the chief objectives are first identified, and the rationales behind some of the specific techniques are sketched out. The review ends with an outline of current trends and recent developments.
Systematic study on heat transfer and surface hydrodynamics of a vertical heat tube in a fluidized bed of FCC particles
Authors: Yao Xiuying , Zhang Yongmin , Lu Chunxi , Han Xiao
Published: September 2014

Bed‐to‐wall heat transfer properties of a vertical heat tube in a fluidized bed of fine fluid catalytic cracking (FCC) particles are measured systematically using a specially designed heat tube. Two important surface hydrodynamic parameters, i.e. the packet fraction (δpa) and mean packet residence time (τpa) based on the packet renewal theory, are determined by an optical fiber probe and a data processing method. The experimental results successfully reveal the axial and radial profiles of heat‐transfer coefficient, the effects of superficial gas velocity, and static bed height on heat‐transfer coefficient, most of which can be explained successfully by the measured τpa, an indicator of packet renewal frequency. τpa is found to play a more dominant role than δpa on bed‐to‐wall heat transfer. With a fitted correction factor, the modified Mickley and Fairbanks model is able to predict the heat‐transfer coefficients with enough accuracy based on the determined packet parameters. © 2014 American Institute of Chemical Engineers AIChE J, 61: 68–83, 2015
Identification of TBX5 mutations in a series of 94 patients with Tetralogy of Fallot
Authors: Baban Anwar , Postma Alex Vincent , Marini Monica , Trocchio Gianluca , Santilli Antonella , Pelegrini Monica , Sirleto Pietro , Lerone Margherita , Albanese Sonia Bernadette , Barnett Phil , Boogerd Cornelis Job , Dallapiccola Bruno , Digilio Maria Cristina , Ravazzolo Roberto , Pongiglione Giacomo
Published: September 2014

Tetralogy of Fallot (TOF) (OMIM #187500) is the most frequent conotruncal congenital heart defect (CHD) with a range of intra‐ and extracardiac phenotypes. TBX5 is a transcription factor with well‐defined roles in heart and forelimb development, and mutations in TBX5 are associated with Holt–Oram syndrome (HOS) (OMIM#142900). Here we report on the screening of 94 TOF patients for mutations in TBX5, NKX2.5 and GATA4 genes. We identified two heterozygous mutations in TBX5. One mutation was detected in a Moroccan patient with TOF, a large ostium secundum atrial septal defect and complete atrioventricular block, and features of HOS including bilateral triphalangeal thumbs and fifth finger clinodactyly. This patient carried a previously described de novo, stop codon mutation (p.R279X) located in exon 8 causing a premature truncated protein. In a second patient from Italy with TOF, ostium secundum atrial septal defect and progressive arrhythmic changes on ECG, we identified a maternally inherited novel mutation in exon 9, which caused a substitution of a serine with a leucine at amino acid position 372 (p.S372L, c.1115C>T). The mother's clinical evaluation demonstrated frequent ventricular extrasystoles and an atrial septal aneurysm. Physical examination and radiographs of the hands showed no apparent skeletal defects in either child or mother. Molecular evaluation of the p.S372L mutation demonstrated a gain‐of‐function phenotype. We also review the literature on the co‐occurrence of TOF and HOS, highlighting its relevance. This is the first systematic screening for TBX5 mutations in TOF patients which detected mutations in two of 94 (2.1%) patients. © 2014 Wiley Periodicals, Inc.
Studying Microstructure in Molecular Crystals With Nanoindentation: Intergrowth Polymorphism in Felodipine
Authors: Mishra Manish Kumar , Desiraju Gautam R. , Ramamurty Upadrasta , Bond Andrew D.
Published: September 2014

Intergrowth polymorphism refers to the existence of distinct structural domains within a single crystal of a compound. The phenomenon is exhibited by form II of the active pharmaceutical ingredient felodipine, and the associated microstructure is a significant feature of the compound’s structural identity. Employing the technique of nanoindentation on form II reveals a bimodal mechanical response on specific single‐crystal faces, demonstrating distinct properties for two polymorphic forms within the same crystal.
Fluorocarbon and Hydrocarbon N‐Heterocyclic (C5–C7) Imidazole‐Based Liquid Crystals
Authors: Chen Hongren , Hong Fengying , Shao Guang , Hang Deyu , Zhao Lei , Zeng Zhuo
Published: September 2014

By using three synthetic protocols, a series of fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based liquid crystals (LCs) and related imidazolium‐based ionic liquid crystals (ILCs) have been prepared. The ring size of the N‐heterocycle and the length of the N‐terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid‐crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole‐based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based LCs and related imidazolium‐based ILCs could be used as new liquid‐crystalline materials.
Synthesis and Photophysical Behavior of a Supramolecular Nanowire made from Dithienylethene‐Bridged Bis(permethyl‐β‐cyclodextrin)s and Porphyrins
Authors: Yang Yang , Zhang Ying‐Ming , Zhang Yue , Xu Xiufang , Liu Yu
Published: September 2014

A photochromic dithienylethene‐bridged bis(permethyl‐β‐cyclodextrin)s was successfully synthesized through an amide condensation reaction, and its photochromic properties were also investigated by 1H NMR spectra and UV/vis spectroscopy. Moreover, taking advantage of the strong interaction between permethyl‐β‐cyclodextrin and water soluble porphyrins, a supramolecular nanowire was then successfully constructed and characterized by UV/vis spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Significantly, the fluorescence resonance energy transfer (FRET) process from the porphyrin to the dithienylethene core can be modulated by alternate irradiation with ultraviolet and visible light and, thus, light‐controlled quenching and recovery of fluorescence of porphyrins was realized.
Coordination Chemistry of Highly Hemilabile Bidentate Sulfoxide N‐Heterocyclic Carbenes with Palladium(II)
Authors: Yu Kuo‐Hsuan , Wang Chia‐Ching , Chang I‐Hsin , Liu Yi‐Hung , Wang Yu , Elsevier Cornelis J. , Liu Shiuh‐Tzung , Chen Jwu‐Ting
Published: September 2014

Imidazolium salts, [RS(O)CH2(C3H3N2)Mes]Cl (R=Me (L1 a), Ph (L1 b)); Mes=mesityl), make convenient carbene precursors. Palladation of L1 a affords the monodentate dinuclear complex, [(PdCl2{MeS(O)CH2(C3H2N2)Mes})2] (2 a), which is converted into trans‐[PdCl2(NHC)2] (trans‐4 a; N‐heterocyclic carbene) with two rotamers in anti and syn configurations. Complex trans‐4 a can isomerize into cis‐4 a(anti) at reflux in acetonitrile. Abstraction of chlorides from 4 a or 4 b leads to the formation of a new dication: trans‐[Pd{RS(O)CH2(C3H2N2)Mes}2](PF6)2 (R=Me (5 a), Ph (5 b)). The X‐ray structure of 5 a provides evidence that the two bidentate SONHC ligands at palladium(II) are in square‐planar geometry. Two sulfoxides are sulfur‐ and oxygen‐bound, and constitute five‐ and six‐membered chelate rings with the metal center, respectively. In acetonitrile, complexes 5 a or 5 b spontaneously transform into cis‐[Pd(NHC)2(NCMe)2](PF6)2. Similar studies of thioether–NHCs have also been examined for comparison. The results indicate that sulfoxides are more labile than thioethers.
Highly Selective and Sensitive Near‐Infrared‐Fluorescent Probes for the Detection of Cellular Hydrogen Sulfide and the Imaging of H2S in Mice
Authors: Wu Haixia , Krishnakumar Saarangan , Yu Jie , Liang Dong , Qi Hongyi , Lee Zheng‐Wei , Deng Lih‐Wen , Huang Dejian
Published: September 2014

Herein, we report the development of two fluorescent probes for the highly selective and sensitive detection of H2S. The probes take advantage of a CuIIcyclen complex, which acts as a reaction center for H2S and as a quencher of BODIPY (boron‐dipyrromethene)‐based fluorophores with emissions at 765 and 680 nm, respectively. These non‐fluorescent probes could only be turned on by the addition of H2S, and not by other potentially interfering biomolecules, including reactive oxygen species, cysteine, and glutathione. In a chemical system, both probes detected H2S with a detection limit of 80 nM. The probes were successfully used for the endogenous detection of H2S in HEK 293 cells, for measuring the H2S‐release activity of dietary organosulfides in MCF‐7 cells, and for the in vivo imaging of H2S in mice.
Analysis of the influence of handset phone position on RF exposure of brain tissue
Authors: Ghanmi Amal , Varsier Nadège , Hadjem Abdelhamid , Conil Emmanuelle , Picon Odile , Wiart Joe
Published: September 2014

Exposure to mobile phone radio frequency (RF) electromagnetic fields depends on many different parameters. For epidemiological studies investigating the risk of brain cancer linked to RF exposure from mobile phones, it is of great interest to characterize brain tissue exposure and to know which parameters this exposure is sensitive to. One such parameter is the position of the phone during communication. In this article, we analyze the influence of the phone position on the brain exposure by comparing the specific absorption rate (SAR) induced in the head by two different mobile phone models operating in Global System for Mobile Communications (GSM) frequency bands. To achieve this objective, 80 different phone positions were chosen using an experiment based on the Latin hypercube sampling (LHS) to select a representative set of positions. The averaged SAR over 10 g (SAR10 g) in the head, the averaged SAR over 1 g (SAR1 g) in the brain, and the averaged SAR in different anatomical brain structures were estimated at 900 and 1800 MHz for the 80 positions. The results illustrate that SAR distributions inside the brain area are sensitive to the position of the mobile phone relative to the head. The results also show that for 5–10% of the studied positions the SAR10 g in the head and the SAR1 g in the brain can be 20% higher than the SAR estimated for the standard cheek position and that the Specific Anthropomorphic Mannequin (SAM) model is conservative for 95% of all the studied positions. Bioelectromagnetics 35:568–579, 2014. © 2014 Wiley Periodicals, Inc.
A Cyclic KLVFF‐Derived Peptide Aggregation Inhibitor Induces the Formation of Less‐Toxic Off‐Pathway Amyloid‐β Oligomers
Authors: Arai Tadamasa , Sasaki Daisuke , Araya Takushi , Sato Takeshi , Sohma Youhei , Kanai Motomu
Published: September 2014

Inhibition of amyloid‐β (Aβ) aggregation could be a target of drug development for the treatment of currently incurable Alzheimer's disease. We previously reported that a head‐to‐tail cyclic peptide of KLVFF (cyclic‐KLVFF), a pentapeptide fragment corresponding to the Aβ16–20 region (which plays a critical role in the generating Aβ fibrils), possesses potent inhibitory activity against Aβ aggregation. Here we found that the inhibitory activity of cyclic‐KLVFF was significantly improved by incorporating an additional phenyl group at the β‐position of the Phe4 side chain (inhibitor 3). Biophysical and biochemical analyses revealed the rapid formation of 3‐embedded oligomer species when Aβ1–42 was mixed with 3. The oligomer species is an “off‐pathway” species with low affinity for cross‐β‐sheet‐specific dye thioflavin T and oligomer‐specific A11 antibodies. The oligomer species had a sub‐nanometer height and little capability of aggregation to amyloid fibrils. Importantly, the toxicity of the oligomer species was significantly lower than that of native Aβ oligomers. These insights will be useful for further refinement of cyclic‐KLVFF‐based aggregation inhibitors.
Quality metrics in cardiac catheterization for congenital heart disease: Utility of 30‐day mortality
Authors: Backes Carl H. , Bergersen Lisa , Rome Jonathan J. , Batlivala Sarosh P. , Glatz Andrew C. , Ovunc Bugsu , David Sthuthi , Rivera Brian K. , Haque Urbee , Kollins Kevin , Yin Han , Holzer Ralf J.
Published: September 2014

Objectives: To characterize the frequency and attributability of death among patients who died within 30 days of their cardiac catheterization (30‐day mortality). Background: 30‐day postprocedure mortality is commonly used as a quality outcome metric in national cardiac catheterization registries. It is unclear if this parameter is sufficiently specific to meaningfully capture mortality attributable to cardiac catheterization in patients with congenital heart disease (CHD). Methods: Multicenter cohort study with 3 participating centers. Records were retrospectively reviewed for patients who died within 30 days of catheterization (06/2007‐06/2012). Attributability of death was assigned to each case. Results: A total of 14,707 cardiac catheterization procedures were performed during the study period. Death occurred within 30 days in 279/14,707 (1.9%) of cases. Among the patients who died, 53% of cases were emergent or urgent cases. The median age was 4 mos (1 day–45 years). Death was attributable to the catheterization procedure in 29/279 (10%) of cases. Death was attributable to cardiac surgery in 14%, precatheterization clinical status in 34%, postcatheterization clinical status in 22%, and noncardiac comorbidity in 19%. In 1%, death attributability could not be established. Conclusions: While valuable in adult settings, 30‐day mortality is inadequate as a quality metric among patients with CHD undergoing cardiac catheterization. To derive the optimal benefit from catheterization registry data, more robust methodologies to capture procedure‐related mortality are needed. © 2014 Wiley Periodicals, Inc.
Outcomes using a clinical practice pathway for the management of pulse loss following pediatric cardiac catheterization
Authors: Glatz Andrew C. , Keashen Rachel , Chang Julie , Balsama Lisa‐Ann , Dori Yoav , Gillespie Matthew J. , Giglia Therese M. , Raffini Leslie , Rome Jonathan J.
Published: September 2014

Objective

Objectives To describe the results of a clinical practice pathway (CPP) for the management of postcatheterization pulse loss in a children's hospital.

Background

Standardized approaches to the diagnosis and management of postcatheterization arterial thrombus are lacking. As a result, substantial practice variation exists.

Methods

Data collected prospectively for quality improvement purposes were retrospectively reviewed.

Results

Since initiation of the CPP, 93/1,672 (5.4%) catheterizations resulted in pulse loss at a median patient age and weight of 73 days (1 day–5.8 years) and 4.8 kg (2–14.1 kg). Arterial thrombus was documented by ultrasound (US) in 85. Of these, 66 resolved by 12 weeks of therapy, seven patients died, and four were lost to follow‐up before completing treatment. Eight patients had persistent thrombus despite a full treatment course (89% success rate in those able to complete treatment). Of patients treated with unfractionated heparin as initial therapy, 46% (17/37) achieved a therapeutic partial thromboplastin time within 12 hr with 19% (67/343) of all levels therapeutic. As a result, the CPP was modified to use enoxaparin as first line agent, of which 57% (41/72) had a therapeutic anti‐Xa level after the 2nd dose and 88% by the 4th dose. No bleeding complications were observed. A priori established process metrics were achieved.

Conclusions

A CPP utilizing early initiation of anticoagulation and US to aid diagnosis of postcatheterization arterial thrombus and response to therapy is feasible and effective. In those able to complete up to 12 weeks of treatment, resolution occurs in nearly 90%. © 2014 Wiley Periodicals, Inc.
Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides Catalyzed by a Keggin‐Type Polyoxometalate‐Supported Rhenium Carbonyl Derivate in Ionic Liquid
Authors: Huo Zhiyuan , Zhao Juan , Bu Zhanwei , Ma Pengtao , Liu Qisen , Niu Jingyang , Wang Jingping
Published: September 2014

A monovacant Keggin‐type polyoxometalate‐supported trirhenium carbonyl derivate [(CH3)4N]5H23[(PW11O39){Re(CO)3}3(μ3‐O)(μ2‐OH)]4⋅24 H2O was synthesized. It was used as a catalyst for the synthesis of cyclic carbonates from carbon dioxide and epoxides under mild reaction conditions with co‐catalyst pyrrolidinium bromide. The catalyst system was recycled 10 times with only a small decline in yield. The catalytic mechanism was hypothesized based on experimental results and the frontier orbitals computed by DFT calculations.
Heterogeneously Catalyzed Hydrogenation of Squalene to Squalane under Mild Conditions
Authors: Pandarus Valerica , Ciriminna Rosaria , Kaliaguine Serge , Béland François , Pagliaro Mario
Published: September 2014

The full chemoselective hydrogenation of highly unsaturated all‐trans linear squalene into valuable fully saturated squalane is achieved smoothly under mild conditions over the sol–gel‐entrapped Pd catalyst SiliaCat Pd0. The catalysis is truly heterogeneous, and the catalyst is stable and recyclable, which opens the route to an easier and less expensive hydrogenation of squalene.
Development of Electrolytes towards Achieving Safe and High‐Performance Energy‐Storage Devices: A Review
Authors: Wang Yu , Zhong Wei‐Hong
Published: September 2014

Increasing interest in flexible/wearable electronics, clean energy, electrical vehicles, and so forth is calling for advanced energy‐storage devices, such as high‐performance lithium‐ion batteries (LIBs), which can not only store energy efficiently and safely, but also possess additional properties, such as good mechanical properties to bear deformations or even to be used as structural components. These expectations first indicate the directions, but also raise new challenges for the advancement of energy materials. As one of the critical components in LIBs, the electrolyte connecting the two electrodes is vital for achieving the desired performances in batteries. In this Review, the developments of various liquid electrolytes (organic, ionic liquid, and aqueous electrolytes), solid electrolytes (solid polymer and inorganic solid), as well as gel electrolytes is briefly summarized and discussed. For each type of electrolyte, the challenging issues and possible solutions are discussed. In particular, safety, ionic conductivity, and contact/interface issues are emphasized. Finally, from a composite point of view, strategies for the development of high‐performance electrolytes with all‐round properties are proposed.
Synthesis of {100} Facet Dominant Anatase TiO2 Nanobelts and the Origin of Facet‐Dependent Photoreactivity
Authors: Pan Feng , Wu Kai , Li Hexing , Xu Guoqin , Chen Wei
Published: September 2014

Sword‐like anatase TiO2 nanobelts exposed with 78 % clean {100} facets were synthesized and the facet‐dependent photoreactivity of anatase TiO2 was investigated. By quantitative comparison with the reference {001} facets, the {100} facets possessed about ten‐times higher active sites density than that on {001} facets, resulting in higher photoreaction efficiency. After the active sites density normalization, the {100} and {001} facets exhibited distinct wavelength‐dependent photocatalytic performance, attributed to the anisotropic electronic structures in TiO2 crystals.
Stereoselective Total Synthesis and Structural Elucidation of (−)‐Indoxamycins A–F
Authors: He Chi , Zhu Chenlong , Wang Bingnan , Ding Hanfeng
Published: September 2014

In this study, a concise and stereoselective approach for the divergent total synthesis of (−)‐indoxamycins A–F is described. The key steps of the strategy include an Ireland–Claisen rearrangement, an enantioselective 1,6‐enyne reductive cyclization, and a tandem 1,2‐addition/oxa‐Michael/methylenation reaction. The relative and absolute configuration of these natural products has been unambiguously elucidated, and their cytotoxic activities against HT‐29 and A‐549 tumor cell lines are also reported.
Dramatic Influence of an Anionic Donor on the Oxygen‐Atom Transfer Reactivity of a MnV–Oxo Complex
Authors: Neu Heather M. , Quesne Matthew G. , Yang Tzuhsiung , Prokop‐Prigge Katharine A. , Lancaster Kyle M. , Donohoe James , DeBeer Serena , de Visser Sam P. , Goldberg David P.
Published: September 2014

Addition of an anionic donor to an MnV(O) porphyrinoid complex causes a dramatic increase in 2‐electron oxygen‐atom‐transfer (OAT) chemistry. The 6‐coordinate [MnV(O)(TBP8Cz)(CN)]− was generated from addition of Bu4N+CN− to the 5‐coordinate MnV(O) precursor. The cyanide‐ligated complex was characterized for the first time by Mn K‐edge X‐ray absorption spectroscopy (XAS) and gives MnO=1.53 Å, MnCN=2.21 Å. In combination with computational studies these distances were shown to correlate with a singlet ground state. Reaction of the CN− complex with thioethers results in OAT to give the corresponding sulfoxide and a 2e−‐reduced MnIII(CN)− complex. Kinetic measurements reveal a dramatic rate enhancement for OAT of approximately 24 000‐fold versus the same reaction for the parent 5‐coordinate complex. An Eyring analysis gives ΔH≠=14 kcal mol−1, ΔS≠=−10 cal mol−1 K−1. Computational studies fully support the structures, spin states, and relative reactivity of the 5‐ and 6‐coordinate MnV(O) complexes.
Unexpected Anion Effect in the Alkoxylation of Alkynes Catalyzed by N‐Heterocyclic Carbene (NHC) Cationic Gold Complexes
Authors: Biasiolo Luca , Trinchillo Marina , Belanzoni Paola , Belpassi Leonardo , Busico Vincenzo , Ciancaleoni Gianluca , D'Amora Angela , Macchioni Alceo , Tarantelli Francesco , Zuccaccia Daniele
Published: September 2014

The intermolecular alkoxylation of alkynes is the oldest application of cationic gold(I) catalysts; however, no systematic experimental data about the role of the anion are available. In this contribution, the role of the anion in this catalytic reaction as promoted by a N‐heterocyclic carbene‐based gold catalyst, [(NHC)AuX] (X=BARF−, BF4−, OTf−, OTs−, TFA−, or OAc−) is analyzed, through a combined experimental (NMR spectroscopy) and theoretical (DFT calculation) approach. The most important factor seems to be the ability to abstract the proton from the methanol during the nucleophilic attack, and such ability is related to the anion basicity. On the other hand, too high coordination power or basicity of the anion worsens the catalytic performance by preventing alkyne coordination or by forming too much free methoxide in solution, which poisons the catalyst. The intermediate coordinating power and basicity of the OTs− anion provides the best compromise to achieve efficient catalysis.
Numerical analysis of solutal Marangoni convections in porous media
Authors: Alizadeh Mostafa , Rostami Behzad , Khosravi Maryam
Published: September 2014

The possibility of instability initiation in porous media by Marangoni convection is studied numerically with a special focus on its application in petroleum engineering and enhanced oil recovery (EOR). Both types of micro‐ and macro‐convections are considered. The finite element method is employed to solve the models numerically. The appropriate Marangoni numbers are introduced according to the model after making equations and boundary conditions dimensionless. In order to evaluate micro‐convections in porous media, the Molenkamp model is extended and validation is performed by comparing concentration maps in a special case. For macro‐convections, a specific concentration distribution is imposed on the boundary to simulate similar conditions in EOR. Results showed that micro‐convections are not strong enough to alter the fluid flow in porous media in applicable ranges of Marangoni numbers and porous media properties. On the other hand, for macro‐convection results, fourteen test cases, each with three different porosities, are defined. As a result, the margin of stability is found and it is also shown that the damping forces of porous media delays the onset of convection.
Relaxation mechanisms and shales
Authors: Washburn Kathryn E.
Published: September 2014

Unconventional petroleum resources present in shales have recently seen increased development due to growing demand for energy worldwide, declining conventional petroleum discoveries, and improved technology for production. Shale reservoirs differ from more conventional reservoirs in both matrix composition and structure, tending to be low in porosity and ultralow in permeability, making traditional laboratory characterization methods difficult to apply. The noninvasiveness of nuclear magnetic resonance (NMR) makes it a favored technique for shale analysis. However, interpretation of NMR relaxometry results for shales is more complex than in traditional reservoirs. Surface relaxivity in conventional reservoirs is predominantly caused by the interaction of fluid molecules with paramagnetic impurities on pore surfaces. However, in shales, small pore sizes coupled with the presence of hydrogen‐rich organic matter can result in more interactions. This article discusses different relaxation mechanisms that may be present in shales and situations where they are relevant. Surface relaxation in organic matter is likely caused by homonuclear dipolar coupling, not paramagnetic impurities, and as such, will have a significant temperature dependence. Due to the small pore sizes in shales, the effect of internal gradients on the signal appears negligible in almost all situations. Analysis of transverse relaxation resulting from organic solids by an inverse Laplace transform may lead to results that are anomalously short and overcall signal intensity. Diffusional coupling between the shale pores confounds interpretation of the NMR response as a pore size distribution. There also appears to be rapid exchange of magnetization between mobile and immobile phases in the samples. © 2014 Wiley Periodicals, Inc. Concepts Magn Reson Part A 43A: 57–78, 2014.
A massive data processing approach for effective trustworthiness in online learning groups
Authors: Miguel Jorge , Caballé Santi , Xhafa Fatos , Prieto Josep
Published: September 2014

This paper proposes a trustworthiness‐based approach for the design of secure learning activities in online learning groups. Although computer‐supported collaborative learning has been widely adopted in many educational institutions over the last decade, there exist still drawbacks that limit its potential. Among these limitations, we investigate on information security vulnerabilities in learning activities, which may be developed in online collaborative learning contexts. Although security advanced methodologies and technologies are deployed in learning management systems, many security vulnerabilities are still not satisfactorily solved. To overcome these deficiencies, we first propose the guidelines of a holistic security model in online collaborative learning through an effective trustworthiness approach. However, as learners' trustworthiness analysis involves large amount of data generated along learning activities, processing this information is computationally costly, especially if required in real time. As the main contribution of this paper, we eventually propose a parallel processing approach, which can considerably decrease the time of data processing, thus allowing for building relevant trustworthiness models to support learning activities even in real time. Copyright © 2014 John Wiley & Sons, Ltd.
Laser Sculpting of Atomic sp, sp2, and sp3 Hybrid Orbitals
Authors: Liu Chunmei , Manz Jörn , Yang Yonggang
Published: September 2014

Atomic sp, sp2, and sp3 hybrid orbitals were introduced by Linus Pauling to explain the nature of the chemical bond. Quantum dynamics simulations show that they can be sculpted by means of a selective series of coherent laser pulses, starting from the 1s orbital of the hydrogen atom. Laser hybridization generates atoms with state‐selective electric dipoles, opening up new possibilities for the study of chemical reaction dynamics and heterogeneous catalysis.
A Fluorescence Switch for the Detection of Nitric Oxide and Histidine and Its Application in Live Cell Imaging
Authors: Sivaraman Gandhi , Anand Thangaraj , Chellappa Duraisamy
Published: September 2014

A rhodamine‐based copper complex as a selective, sensitive turn‐on fluorescent chemosensor for NO/histidine has been developed. A conspicuous fluorescence enhancement was observed in the presence of nitric oxide/histidine. The probe was specific towards NO over other reactive oxygen species and reactive nitrogen species. The probe showed selective fluorescence enhancement with histidine; the other naturally occurring amino acids did not result in fluorescence enhancement. EPR and ESIMS studies clearly showed that NO‐induced reduction of copper ions leads to the fluorescence enhancement. The viability of the probe for fluorescent imaging of nitric oxide and histidine in living cells has been demonstrated by means of confocal laser scanning microscopy experiments.
Synthesis, Characterization, and Interconversion of β‐Diketiminato Nickel NxHy Complexes
Authors: Köthe Claudia , Braun Beatrice , Herwig Christian , Limberg Christian
Published: September 2014

The β‐diketiminato nickel(II) hydrazido(–1) complex [LtBuNi(η2‐N2H3)], (IV) was investigated with respect to its deprotonation/protonation behavior. Deprotonation with KOtBu led to [LtBuNi(μ,η2:η2‐N2H2)K(solv)] (1), and this process was proven to be reversible. Spectroscopic and DFT studies revealed an electronic structure intermediate between nickel(II) hydrazido(–2) and nickel(0) diazene. On the other hand, protonation of IV with [LutH]OTf reversibly generated the hydrazine complex [LtBuNi(η2‐N2H4)]OTf (2). Warming a solution of IV led to N–N bond cleavage yielding the nickel(I) ammine complex [LtBuNi(NH3)], (3). Hence, LtBuNi moieties were shown to effectively activate NxHy species for diverse conversions.
The activation of spinal astrocytes contributes to preoperative anxiety‐induced persistent post‐operative pain in a rat model of incisional pain
Authors: Liu Y. , Hou B. , Zhang W. , Sun Y.‐E. , Li L. , Ma Z. , Gu X.
Published: September 2014

Background

Preoperative anxiety, a clinically significant problem for many patients undergoing surgery, is associated with prolonged and exacerbated post‐operative pain. To date, the mechanisms of preoperative anxiety‐induced persistent post‐operative pain remain unclear. The present study aimed to provide a rat model of preoperative anxiety‐induced persistent post‐operative pain using the single‐prolonged stress (SPS) procedure to induce preoperative anxiety‐like behaviours, and to explore the role of spinal astrocytes in this phenomenon.

Methods

Rats were exposed to the SPS procedure to induce preoperative anxiety‐like behaviours. Subsequently, acute post‐operative pain was developed using a 1‐cm longitudinal incision through skin and fascia of the plantar aspect of the right hindpaw. Mechanical allodynia was measured before and after the incision. Immunofluorescence assay was used to assess the expression of glial fibrillary acidic protein and the activation of astrocytes in spinal dorsal horn.

Results

The SPS performed before the incision resulted in (1) enhanced preoperative anxiety‐like behaviours as revealed by the elevated plus maze tests; (2) exacerbated and prolonged mechanical allodynia that lasted for at least 28 post‐operative days; and (3) activation of astrocytes in the lumbar spinal dorsal horn.

Conclusions

The data suggest that this rat model, which could mimic the clinical persistent post‐operative pain induced by preoperative anxiety, may be a useful tool to explore the mechanisms as well as effective prevention and treatment for this problem. Furthermore, spinal astrocytes activation may contribute to the development of post‐operative hyperalgesia in this model.
Electrochemical Behaviour of HOPG and CVD‐Grown Graphene Electrodes Modified with Thick Anthraquinone Films by Diazonium Reduction
Authors: Kibena Elo , Marandi Margus , Sammelselg Väino , Tammeveski Kaido , Jensen Bjarke B. E. , Mortensen Anders B. , Lillethorup Mie , Kongsfelt Mikkel , Pedersen Steen U. , Daasbjerg Kim
Published: September 2014

Highly oriented pyrolytic graphite (HOPG) and graphene grown on Ni (Ni‐Gra) or Cu (Cu‐Gra) by chemical vapour deposition were modified with thick anthraquinone (AQ) films (7−60 nm) by redox grafting of the pertinent diazonium salt. Glassy carbon (GC) electrodes were used for comparison. The AQ‐modified GC electrodes showed excellent blocking properties towards the Fe(CN)63−/4− redox probe, although it was noted that in the case of Ni‐Gra and Cu‐Gra, the blocking ability depended strongly on the underlying substrate. Oxygen reduction studies revealed good electrocatalytic activity of AQ‐modified HOPG, Ni‐Gra, and Cu‐Gra, compared with the bare electrodes.
Nuclear fusion as a massive, clean, and inexhaustible energy source for the second half of the century: brief history, status, and perspective
Authors: Sánchez Joaquin
Published: September 2014

Fusion energy, based on the use of broadly available inexhaustible resources as lithium and deuterium and with minimal impact to the environment, aims at a change in the energy supply paradigm: instead of its current dependence on natural resources and environmental impact, energy would become a technology‐dependent resource with unlimited adaptive availability and whose unit cost should decrease as technology progresses. This article intends to give a picture of where fusion research stands today and the perspectives: the achievements, the difficulties, the current status, marked by the construction of the ITER experiment which will demonstrate the scientific feasibility of fusion power, and the perspectives toward the first demonstration power plant, DEMO, which, according to the European Roadmap, could start the construction shortly after the full power experiments in ITER (<2030) and be in full operation, generating net electricity into the grid, by 2050.
Reconstructing the development of sampled sites on fluvial island surfaces of the Tagliamento River, Italy, from historical sources
Authors: Mardhiah Ulfah , Rillig Matthias C , Gurnell Angela
Published: September 2014

In parallel with research on surface sediment characteristics of evolving island features (patches) along an island‐braided reach of the Tagliamento River, Italy, the present research reconstructed the development of the sampled sites using historical information coupled with field measurements. Since any field sediment sampling programme inevitably focuses on small areas (of the order of a few metres), the historical sources were assessed bearing in mind their spatial resolution and geographical accuracy in relation to the size of the sampled sites, and the information they could provide regarding the historical evolution of those sites.

The analysis combined four sources of information: (i) river stage records revealed flood events that had the potential to reset bar surfaces and float in wood and seeds to initiate vegetation colonization; (ii) oblique ground photographs identified areas of the river's active corridor where riparian vegetation colonization appeared to have been initiated by specific flood events; (iii) dendrochronology was used to estimate the age of sampled sites; (iv) field‐measured geographical locations of the sampled sites were combined with historical vertical areal imagery to further establish sampling site age and changes in vegetation cover from 1944 to 2012.

A chronosequence of sampled sites (0, 2, 8, 12, 40 years) was established. Vegetation colonization and island development showed a statistically significant development trajectory among sites of each age across the 40 year period following formative floods in 1965–1966, 2000, 2004 and a flow pulse in 2010. The trajectory progressed through pioneer and building island stages until vegetated areas became part of established islands. Evidence from the younger sites indicates that the pioneer island phase lasts up to eight years. Evidence from the oldest site indicates a building island phase lasting a maximum of 30 years, but probably a lot less. Copyright © 2014 John Wiley & Sons, Ltd.
In vivo and in vitro changes in neurochemical parameters related to mercury concentrations from specific brain regions of polar bears (Ursus maritimus)
Authors: Krey Anke , Kwan Michael , Chan Hing Man
Published: September 2014

Mercury (Hg) has been detected in polar bear brain tissue, but its biological effects are not well known. Relationships between Hg concentrations and neurochemical enzyme activities and receptor binding were assessed in the cerebellum, frontal lobes, and occipital lobes of 24 polar bears collected from Nunavik (Northern Quebec), Canada. The concentration–response relationship was further studied with in vitro experiments using pooled brain homogenate of 12 randomly chosen bears. In environmentally exposed brain samples, there was no correlative relationship between Hg concentration and cholinesterase (ChE) activity or muscarinic acetylcholine receptor (mAChR) binding in any of the 3 brain regions. Monoamine oxidase (MAO) activity in the occipital lobe showed a negative correlative relationship with total Hg concentration. In vitro experiments, however, demonstrated that Hg (mercuric chloride and methylmercury chloride) can inhibit ChE and MAO activities and muscarinic mAChR binding. These results show that Hg can alter neurobiochemical parameters but the current environmental Hg exposure level does have an effect on the neurochemistry of polar bears from northern Canada. Environ Toxicol Chem 2014;33:2463–2471. © 2014 SETAC
USING MODERN STATISTICAL METHODS TO IMPROVE THE PRESENTATION OF THE ANNUAL SUMMARIES OF GRE CANDIDATE BACKGROUND DATA
Authors: Holland Paul W. , Thayer Dorothy T.
Published: September 2014

This project has three separate components. The first is an analysis of the background data for GRE test takers using log‐linear models for multi‐way cross‐classifications. The second is the computation of ethnic group GRE verbal and quantitative score means that are standardized for background data. The third is an analysis of the non‐responses to the questions in the GRE background questionnaire. The data used in the analyses are from the 1975–76 and 1976–77 testing years.

An appendix is included that gives versions of the published tables separately for graduate students and nongraduate students. This report was intended as an internal working paper for use by ETS staff.
SECTION PRE‐EQUATING IN THE PRESENCE OF PRACTICE EFFECTS
Authors: Holland Paul W. , Thayer Dorothy T.
Published: September 2014

Section pre‐equating (SPE) is a new method for equating tests that was developed in response to test disclosure legislation. It is designed to equate a new test to an old test prior to the actual use of the new test, and makes extensive use of experimental sections of a testing instrument. This paper extends the theory behind SPE to allow for the effects of practice on both the old and the new tests, and gives a unified and generalized account of SPE.
SPECULATIONS ON THE FUTURE OF TEST DESIGN
Authors: Bejar Isaac I.
Published: September 2014

The paper discusses the potential benefits of integrating technology, cognitive science, and psychometric theory. It is argued that even though adaptive testing, as currently implemented, is an important achievement, it will be necessary to pay close attention to the psychological foundation of tests to continue advancing the state of the art. Such an effort requires construct validation in the broadest sense, as well as focusing on items and why they differ with respect to psychometric parameters, specially difficulty. This approach opens the possibility of generating items with better control of their psychometric characteristics and ultimately the development of computer‐based tests that are solidly anchored in psychological theory.
A PROFILE OF PREPARATION IN ENGLISH: PHASE II
Authors: Ward William C. , Carlson Sybil B.
Published: September 2014

This is the report of a project that was undertaken to develop and validate a method for collecting and reporting information about students' preparation in English for college‐level work. Information was gathered from students through a self‐report inventory, Experiences in English. Then a prototype report was prepared in the form of a profile–an evaluation of a student's strengths and weaknesses in each of several major aspects of use of the language.
ON STATE EDUCATION STATISTICS
Authors: Wainer Howard , Rosenbaum Paul R. , Swinton Spencer , Wang Minhwei
Published: September 2014

State Education Statisticsis a table of information, aggregated to the state level. Its goal appears to be that of a thermometer to measure the health of the American educational system. As such, its usefulness is limited by three problems:

Some outcome variables–ACT and SAT test scores–are produced by a highly self‐selected sample of individuals, so that the differences observed in outcome can be caused by differences in performance, differences in selection ratio and/or differences in selection rules. We were unable to disentangle these through statistical adjustments.

Some input variables were calculated on the population as a whole (i.e., per capita income, average teachers' salary) rather than on the group characterized by the outcome variable (i.e., those individuals taking the SAT). These are often profoundly different and can cause substantial biases in the estimation of statistical measures of the interrelationships among the variables.

Some input variables are inappropriately measured or scaled for the purposes intended. For example, teachers' salaries are given in current rather than constant dollars. Thus, one might conclude that over the ten years considered teachers' salaries went up 81%, rather than the more correct conclusion that, in constant dollars, they declined 20%.

Among the recommendations proposed to solve these problems is an expansion of the National Assessment of Educational Progress (NAEP) to allow accurate state estimates of students performance, as well as expanding the range of areas covered to more fully measure the section of the students' population intending postsecondary education.
FITTING ITEM CHARACTERISTIC CURVES WITH SPLINE FUNCTIONS
Authors: Winsberg Suzanne , Thissen David , Wainer Howard
Published: September 2014

In most item response theory models a particular mathematical form is assumed for all item characteristic curves, e.g., a logistic function. It could be desirable, however, to estimate the shape of the item characteristic curves without prior restrictive assumptions about its mathematical form. We have developed a practical method of estimating the shape of item response functions leading to smooth flexible functions and numerically stable calculations. In our approach the probability of success of an item is represented as a monotone function of the ability evaluated by the item. The function is represented as a monotone spline. We use the technique developed by Bock and Aitkin (1981) for marginal maximum likelihood estimation of the item parameters. Examples of real and artificial data are presented.
SEX DIFFERENCES IN THE ACADEMIC PERFORMANCE OF SCHOLASTIC APTITUDE TEST TAKERS
Authors: Clark Mary Jo , Grandy Jerilee
Published: September 2014

The number of women college students has increased dramatically over the past fifteen years; in this same time period, the average College Board Scholastic Aptitude Test (SAT) scores for women have declined more than the scores for men. This study summarizes recent evidence concerning the academic performance of women and men by examining sex differences among (1) all SAT takers, (2) test takers grouped by anticipated major field of study, and (3) college freshman year courses and grades.

Three major research questions guided this study: Are there consistent differences in the intellectual abilities of men and women? Do precollege admissions variables predict college performance with equal accuracy for women and men? Have the contents or structure of the SAT contributed to observed sex differences in performance on the test?

Though the men and women who take the SAT differ in high school courses and grade point average, major field and career interests, and socioeconomic backgrounds, neither these differences nor research evidence on differential cognitive functioning were found sufficient to account for all of the observed sex differences in performance on the SAT. Some but not all of the male‐female differences in scores on the mathematics portion of the SAT were accounted for by differences in the depth and recency of course preparation. The observed‐first‐year college grades of women were slightly underpredicted by test scores and high school grades, but the magnitude of the underprediction was very small. While specific changes in the contents or structure of the SAT could not be associated with score changes, it seems likely that numerous small adjustments have played some part in recent shifts among the average test scores of women and men.

Consistent with recent literature on sex differences in cognitive performance, this study concludes that sex‐related SAT differences are very small relative to the generally similar levels of performance by men and women, and that using both test scores and high school records to predict first‐year college grades continues to work reasonably well for both sexes.
RECENT DEVELOPMENTS IN THE FACTOR ANALYSIS OF CATEGORICAL VARIABLES
Authors: Mislevy Robert J.
Published: September 2014

Despite known shortcomings of the procedure, exploratory factor analysis of dichotomous test items has been limited, until recently, to unweighted analyses of matrices of tetrachoric correlations. Superior methods have begun to appear in the literature, in professional symposia, and in computer programs. This paper places these developments in a unified framework, from a review of the classical common factor model for measured variables through generalized least squares and marginal maximum likelihod solutions for dichotomous data. Further extensions of the model are also reported as work in progress.
AN ALTERNATE DEFINITION OF THE ETS DELTA SCALE OF ITEM DIFFICULTY
Authors: Holland Paul W. , Thayer Dorothy T.
Published: September 2014

This note develops an alternative definition of the “delta scale” of item difficulty that is used at ETS. A comparison is given with the traditional definition of the delta scale that is based on the normal distribution. Some advantages of the alternative scale are mentioned.