bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clustering in Analytical Chemistry
Authors: Drab Klaudia , Daszykowski Michal 
Published: February 2014

Abstract
Data clustering plays an important role in the exploratory analysis of analytical data, and the use of clustering methods has been acknowledged in different fields of science. In this paper, principles of data clustering are presented with a direct focus onclustering of analytical data. The role of the clustering process in the analytical workflow is underlined, and its potential impact on the analytical workflow is emphasized.
Experimental Design in Analytical Chemistry—Part I: Theory
Authors: Ebrahimi-Najafabadi Heshmatollah , Leardi Riccardo , Jalali-Heravi Mehdi 
Published: February 2014

Abstract
This paper reviews the main concepts of experimental design applicable to the optimization of analytical chemistry techniques. The critical steps and tools for screening, including Plackett-Burman, factorial and fractional factorial designs, and response surface methodology such as central composite, Box-Behnken, and Doehlert designs, are discussed. Some useful routines are also presented for performing the procedures.
Reevaluating Significance of Perineural Invasion in Gastric Cancer Based on Double Immunohistochemical Staining
Authors: Zhou Zhi-Hua , Xu Gui-Fang , Zhang Wei-Jie , Zhao Hai-Bin , Wu Yao-Yi 
Published: January 2014

Context.—In gastric cancer, the significance of perineural invasion remains controversial. Detecting perineural invasion with hematoxylin-eosin staining often leads to misdiagnosis. Labeling nerves by immunohistochemistry greatly assists perineural invasion detection, but it might also be misdiagnosed, because scattered cancer cells are difficult to recognize.Objective.—To reevaluate the significance of perineural invasion in gastric cancer by double immunohistochemical staining that labels both nerves and cancer cells, and to examine agreements on perineural invasion detection between double immunohistochemical staining and single immunochemical staining (to label nerves) or hematoxylin-eosin staining.Design.—We evaluated perineural invasion in 160 cases of gastric cancer with double immunohistochemical staining, single immunochemical staining, and hematoxylin-eosin staining, respectively; then we investigated the prognostic significance of perineural invasion.Results.—Perineural invasion was detected in 65.0% (104 of 160), 38.1% (61 of 160), and 56.9% (91 of 160) of cases with double immunohistochemical staining, hematoxylin-eosin staining, and single immunohistochemical staining, respectively. Agreement was low between double staining and hematoxylin-eosin staining (κ = .34), and most false reports occurred in diffuse gastric cancer. Agreement between single immunochemical staining and double staining was good (κ = .67), but it declined in diffuse gastric cancer (κ = .28). Perineural invasion was closely associated with other clinicopathologic variables. Although perineural invasion–positive patients had a worse outcome than perineural invasion–negative patients, it was not an independent prognostic factor (P = .11; hazard ratio, 0.637; 95% confidence interval, 0.366–1.110).Conclusions.—Double immunohistochemical staining could improve accuracy of perineural invasion detection in gastric cancer, particularly in the diffuse type. Moreover, perineural invasion predicts a poor outcome in gastric cancer, but it cannot provide more information than traditional clinicopathologic variables.
The Networked Infrastructure of Fossil Capitalism: Implications of the New Pipeline Debates for Environmental Justice in Canada
Authors: Scott Dayna Nadine 
Published: January 2014

A read of the critical geography literature on the concept of “networked infrastructures” generates two arguments in relation to the environmental justice implications of the new pipeline debates. First, the proposed coast-to-coast pipeline is likely to exacerbate existing environmental inequities in Canada. Conceiving of the crude oil in a pipeline as a material flow of commodified nature demonstrates that, at the end of the pipe, inputs of labour, technology and capital are required to convert the crude into useable forms of energy. This leads to a serious engagement with the communities at the ends of the proposed pipes. Here, I illustrate the type of analysis that is required with a preliminary examination of the expected environmental health impacts from increased refinery emissions in Sarnia, Montréal and Saint John. Second, the notion that pipelines, despite their vital effects, are fixed and durable installations of built infrastructure—lending a marked inertia to the routes they cement—produces intergenerational equity concerns in relation to fossil capitalism. These concerns are brought powerfully to the fore by activists under the banner of Idle No More. In fact, it is this growing indigenous resistance movement centered on lands and resources that best illustrates the obvious contradiction: the permanence of the pipelines on the landscape, once built, underscores the gravity of the choices we are weighing, just as the active resistance of indigenous people across the county reveals the inherent instability of the networked infrastructure.
What is responsible for the strong observed asymmetry in teleconnections between El Niño and La Niña?
Authors: Zhang Tao , Perlwitz Judith , Hoerling Martin P. 
Published: January 2014

AbstractA large asymmetric component (El Niño + La Niña) of El Niño–Southern Oscillation (ENSO)‐related teleconnections over North America is found during 1984–2009 that is comparable in strength to the commonly studied symmetric component (El Niño − La Niña). Climate reforecasts spanning this period are diagnosed in order to understand the processes responsible for the observed asymmetry. It is confirmed that an asymmetric component is indeed a fundamental property of atmospheric responses to recent ENSO forcing. Each and every composite of a 16‐member reforecast ensemble has appreciable asymmetry in tropical Pacific rainfall, upper tropospheric Pacific‐North American circulation patterns, and contiguous U.S. surface temperatures. There is considerable sampling variability in the magnitude of this asymmetric component among individual reforecast composites. We argue therefore that the true sea surface temperature boundary‐forced signal of ENSO teleconnections is likely composed of a symmetric component having greater magnitude than its asymmetric component, though the latter is an important property of how ENSO affects North American climate.
Electron energization and transport in the magnetotail during substorms
Authors: Pan Qingjiang , Ashour‐Abdalla Maha , Walker Raymond J. , El‐Alaoui Mostafa 
Published: January 2014

AbstractIt has been suggested recently that electrons are accelerated both near the reconnection site and during subsequent earthward transport. We provide global and quantitative evidence for this two‐step process by examining electron energization during a substorm event that occurred on 11 March 2008, when the Earth's magnetosphere was immersed in southward interplanetary magnetic field and high‐speed solar wind. The approach is to integrate coordinated measurements by Time History of Events and Macroscale Interactions during Substorms (THEMIS), global magnetohydrodynamic (MHD) modeling of the magnetosphere driven by upstream solar wind conditions, and large‐scale kinetics (LSK) simulation. In this event, THEMIS P2 at XGSM ~ − 15 RE detected a dipolarization pulse‐like magnetic structure coupled with energetic electron flux increase. About 1 min later, P3 and P4 at XGSM ~ − 10 RE observed dipolarized magnetic field and even larger flux increase. These multipoint data are applied to benchmark the MHD/LSK simulation. We quantify electron energization near the reconnection site and during earthward transport. We show that electrons were initially energized near the reconnection site, and subsequently further adiabatically accelerated far away from the reconnection site as the dipolarization front formed and grew. The adiabatic enhancement was rather effective given steep source electron distribution as a function of energy. In the outer magnetosphere with strong flows, E × B drift statistically dominated electron guiding center motion; thus, electrons were transported along the flow channel with small spatial diffusion. Close to the Earth, gradient and curvature drifts became appreciable; therefore, electrons circled around the region of large magnetic field.
Variability in surface meteorology and air‐sea fluxes due to cumulus convective systems observed during CINDY/DYNAMO
Authors: Yokoi Satoru , Katsumata Masaki , Yoneyama Kunio 
Published: January 2014

AbstractThis study examines the variability in surface meteorological parameters and air‐sea heat fluxes due to cold pools emanating from cumulus convective systems observed over the tropical Indian Ocean in November 2011. In particular, this study focuses on convective systems that are spatially smaller than mesoscale convective systems in a southeasterly trade wind environment. Composite analyses of convectively active periods show an increase in the sensible heat flux by 15–20 W m−2 that is primarily attributed to an increase in the difference between the surface air temperature and sea surface temperature and an increase in the latent heat flux by 30–70 W m−2 due to enhanced surface wind speeds. A succession of convectively active periods leads to a greater influence than those occurring independently. The direction of the surface wind velocity anomaly due to cold pools tends to be close to that of the environmental wind velocity, resulting in an efficient enhancement of wind speed. This study also demonstrates the close relation between cold pool intensities and convective activity. In particular, two measures of cold pool intensity, a minimum surface air temperature and a maximum amount of surface wind speed enhancement, are correlated with each other and with the convective activity around the observation point measured by radar‐estimated rainfall and radar echo coverage.
Cluster observations of fast magnetosonic waves in the heliosphere current sheet
Authors: Dai Lei , Wygant John R. , Cattell Cynthia A. , Thaller Scott , Kersten Kris , Breneman Aaron , Tang Xiangwei 
Published: January 2014

AbstractWe present Cluster spacecraft observations of large‐amplitude (δ|B|/|B|∼1) fast‐mode magnetosonic waves in the heliospheric current sheet (HCS). The crossings of the HCS and the associated heliospheric plasma sheet (HPS) are encountered by Cluster in the near‐Earth solar wind and by ACE upstream of Earth. Multiple current layers are detected in correspondence with small‐scale discontinuities in the regime of open magnetic field lines within the HCS. Fast magnetosonic waves are observed at one current layer, accompanying the phase‐steeped edge of a large‐amplitude transverse Alfvén wave. The observed fast‐mode waves are in the frequency range 0.01 Hz–0.2 Hz, characterized by a strong correlation between variations of plasma density and magnetic field strength. Analysis of ratio δE/δBindicate that the fast‐mode wave packet consists of an antisunward propagating component and a larger sunward propagating component in the rest frame of the solar wind. The fast‐mode waves are not observed by ACE in the upstream solar wind. The generation of the fast‐mode waves may relate to the development of the phase‐steeped Alfvén wave and has profound effects on the evolution of the solar wind plasma.
Birth month associations with height, head circumference, and limb lengths among peruvian children
Authors: Pomeroy Emma , Wells Jonathan C.K. , Stanojevic Sanja , Miranda J. Jaime , Cole Tim J. , Stock Jay T. 
Published: January 2014

ABSTRACTAssociations between season of birth and body size, morbidity, and mortality have been widely documented, but it is unclear whether different parts of the body are differentially sensitive, and if such effects persist through childhood. This may be relevant to understanding the relationship between early life environment and body size and proportions. We investigated associations between birth month and anthropometry among rural highland (n = 162) and urban lowland (n = 184) Peruvian children aged 6 months to 8 years. Stature; head‐trunk height; total limb, ulna, tibia, hand, and foot lengths; head circumference; and limb measurements relative to head‐trunk height were converted to internal age‐sex‐specific z scores. Lowland and highland datasets were then analyzed separately for birth month trends using cosinor analysis, as urban conditions likely provide a more consistent environment compared with anticipated seasonal variation in the rural highlands. Among highland children birth month associations were significant most strongly for tibia length, followed by total lower limb length and stature, with a peak among November births. Results were not significant for other measurements or among lowland children. The results suggest a prenatal or early postnatal environmental effect on growth that is more marked in limb lengths than trunk length or head size, and persists across the age range studied. We suggest that the results may reflect seasonal variation in maternal nutrition in the rural highlands, but other hypotheses such as variation in maternal vitamin D levels cannot be excluded. Am J Phys Anthropol 154:115–124, 2014. © 2014 The Authors. American Journal of Physical Anthropology Published by Wiley Periodicals, Inc.
Aktivierung von Schwefelhexafluorid an hoch reduzierten niedrig koordinierten Nickel‐Distickstoff‐Komplexen
Authors: Holze Patrick , Horn Bettina , Limberg Christian , Matlachowski Corinna , Mebs Stefan 
Published: January 2014

AbstractDas Klimagas Schwefelhexafluorid ist in der Literatur ein viel verwendetes Standardbeispiel für ein sehr reaktionsträges anorganisches Molekül, das selbst durch Disauerstoff in einer elektrischen Entladung nicht angegriffen wird. Dennoch sind reduzierte β‐Diketiminato‐Nickel‐Komplexe unter Standardbedingungen in der Lage, SF6 in Fluorido‐ und Sulfido‐Verbindungen zu überführen. Das Fluorido‐Produkt besitzt dabei eine präzedenzlose [NiF]+‐Einheit, bei der das Nickelatom nur dreifach koordiniert ist. Der Sulfido‐Komplex beinhaltet eine seltene nahezu lineare [Ni(μ‐S)Ni]2+‐Anordnung. Die Reaktion wurde mittels 1H‐NMR‐, IR‐ und ESR‐spektroskopischen Methoden untersucht. Diese führten zur Identifizierung einer Zwischenstufe und gewährten so einen Einblick in den Mechanismus der 8‐Elektronen‐Reduktion von SF6 .
Rapid Synthesis of Fused N‐Heterocycles by Transition‐Metal‐Free Electrophilic Amination of Arene CH Bonds
Authors: Gao Hongyin , Xu Qing‐Long , Yousufuddin Muhammed , Ess Daniel H. , Kürti László 
Published: January 2014

AbstractWe disclose an efficient and operationally simple protocol for the preparation of fused N‐heterocycles starting from readily available 2‐nitrobiaryls and PhMgBr under mild conditions. More than two dozen N‐heterocycles, including two bioactive natural products, have been synthesized using this method. A stepwise electrophilic aromatic cyclization mechanism was proposed by DFT calculations.
Structure‐Based Approach To Improve a Small‐Molecule Inhibitor by the Use of a Competitive Peptide Ligand
Authors: Ono Katsuki , Takeuchi Koh , Ueda Hiroshi , Morita Yasuhiro , Tanimura Ryuji , Shimada Ichio , Takahashi Hideo 
Published: January 2014

AbstractStructural information about the target–compound complex is invaluable in the early stage of drug discovery. In particular, it is important to know into which part of the initial compound additional interaction sites could be introduced to improve its affinity. Herein, we demonstrate that the affinity of a small‐molecule inhibitor for its target protein could be successfully improved by the constructive introduction of the interaction mode of a competitive peptide. The strategy involved the discrimination of overlapping and non‐overlapping peptide–compound pharmacophores by the use of a ligand‐based NMR spectroscopic approach, INPHARMA. The obtained results enabled the design of a new compound with improved affinity for the platelet receptor glycoprotein VI (GPVI). The approach proposed herein efficiently combines the advantages of compounds and peptides for the development of higher‐affinity druglike ligands.
Mixed IR/Vis Two‐Dimensional Spectroscopy: Chemical Exchange beyond the Vibrational Lifetime and Sub‐ensemble Selective Photochemistry
Authors: van Wilderen Luuk J. G. W. , Messmer Andreas T. , Bredenbeck Jens 
Published: January 2014

AbstractTwo‐dimensional exchange spectroscopy (2D EXSY) is a powerful method to study the interconversion (chemical exchange) of molecular species in equilibrium. This method has recently been realized in femtosecond 2D‐IR spectroscopy, dramatically increasing the time resolution. However, current implementations allow the EXSY signal (and therefore the chemical process of interest) only to be tracked during the lifetime (T1) of the observed spectroscopic transition. This is a severe limitation, as typical vibrational T1 are only a few ps. An IR/Vis pulse sequence is presented that overcomes this limit and makes the EXSY signal independent of T1. The same pulse sequence allows to collect time‐resolved IR spectra after electronic excitation of a particular chemical species in a mixture of species with strongly overlapping UV/Vis spectra. Different photoreaction pathways and dynamics of coexisting isomers or of species involved in different intermolecular interactions can thus be revealed, even if the species cannot be isolated because they are in rapid equilibrium.
Experimental Charge Density Study of a Silylone
Authors: Niepötter Benedikt , Herbst‐Irmer Regine , Kratzert Daniel , Samuel Prinson P. , Mondal Kartik Chandra , Roesky Herbert W. , Jerabek Paul , Frenking Gernot , Stalke Dietmar 
Published: January 2014

AbstractAn experimental and theoretical charge density study confirms the interpretation of (cAAC)2Si as a silylone to be valid. Two separated VSCCs present in the non‐bonding region of the central silicon are indicative for two lone pairs. In the experiment, both the two crystallographically independent SiC bond lengths and ellipticities vary notably. It is only the cyclohexyl derivative that shows significant differences in these values, both in the silylones and the germylones. Only by calculating increasing spheres of surrounding point charges we were able to recover the changes in the properties of the charge density distribution caused by weak intermolecular interactions. The nitrogen–carbene‐carbon bond seems to have a significant double‐bond character, indicating a singlet state for the carbene carbon, which is needed for donor acceptor bonding. Thus the sum of bond angles at the nitrogen atoms seems to be a reasonable estimate for singlet versus triplet state of cAACs.
Rhodium(II)‐Catalyzed Nondirected Oxidative Alkenylation of Arenes: Arene Loading at One Equivalent
Authors: Vora Harit U. , Silvestri Anthony P. , Engelin Casper J. , Yu Jin‐Quan 
Published: January 2014

AbstractA bimetallic RhII catalyst promoted the CH alkenylation of simple arenes at 1.0 equivalent without the use of a directing group. A phosphine ligand as well as cooperative reoxidation of RhII with Cu(TFA)2 and V2O5 proved essential in providing monoalkenylated products in good yields and selectivities, especially with di‐ and trisubstituted arenes.
Antibacterial, flame retardant, and physico‐chemical properties of cotton fabric graft copolymerized with a binary mixture of acrylonitrile and 4‐vinylpyridine
Authors: Kaur Inderjeet , Bhati Pooja , Sharma Bharti 
Published: January 2014

ABSTRACTModification of cotton fabric has been carried out through chemically induced graft copolymerization of binary mixture of acrylonitrile (AN) and 4‐vinyl pyridine (4‐VP) using ceric ammonium nitrate, (CAN) as initiator. Maximum percentage of grafting (151.28%) has been obtained at [4‐VP] = 0.376 mol L−1 and [AN] = 1.221 mol L−1, [CAN] = 0.0255 mol L−1 and [HNO3] = 0.9585 mol L−1 in 25mL of water at 70°C in 180 min. Post quarternization and phosphorylation reactions of the grey and grafted cotton fabrics have been carried out to study their antibacterial and flame retardant properties respectively. The fabrics have been characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The physico‐chemical properties such as wettability, moisture regain, crease recovery and tensile strength of the grey and grafted cotton fabric have also been evaluated. The modified fabric has been shown to exhibit excellent antibacterial and flame retarding properties with improved physico‐chemical properties except for the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40415.
Gelatin‐carbohydrate phase‐separated hydrogels as bioactive carriers in vaginal delivery: Preparation and physical characterizations
Authors: Singh Vinay Kumar , Sagiri Sai Sateesh , Pal Kunal , Khade Shankar M. , Pradhan Dillip K. , Bhattacharya Mrinal K. 
Published: January 2014

ABSTRACTThe current study focuses on the alteration of properties of the gelatin hydrogels using polysaccharides (e.g., maltodextrin, dextran, and sodium carboxymethyl cellulose) for probable use in vaginal delivery of antimicrobials. The hydrogels were prepared by varying the proportions of gelatin and polysaccharides and were characterized by microscopy, mechanical testing, and impedance spectroscopy. Metronidazole (MZ), drug of choice for the treatment of bacterial vaginosis, was incorporated within the hydrogels. In vitro release studies of MZ from the hydrogels was studied in‐depth using modified Franz's diffusion cell. Antimicrobial efficiency of the MZ‐loaded hydrogels was tested against E. coli and B. subtilis. The results suggested that the incorporation of polysaccharides resulted in the phase‐separated hydrogels. The properties of the hydrogels was found be suitable for vaginal delivery. The drug release and antimicrobial efficiency from the hydrogels suggested that the developed hydrogels may be used for the delivery of antimicrobials in the vaginal lumen. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40445.
Preparation of Monodisperse Ferrite Nanocrystals with Tunable Morphology and Magnetic Properties
Authors: Liang Ruizheng , Tian Rui , Liu Zhihui , Yan Dongpeng , Wei Min 
Published: January 2014

AbstractThe synthesis of monodisperse magnetic ferrite nanomaterials plays an important role in several scientific and technological areas. In this work, dibasic spinel MFe2O4 (M=Mg, Ni, Co, Fe, Mn) and polybasic spinel ferrite MCoFeO4 (M=Mg, Ni, Mn, MgNi) nanocrystals were prepared by the calcination of layered double hydroxide (LDH) precursors at 900 °C, which was confirmed by X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the as‐obtained spinel ferrites present a single‐crystalline nature with uniform particle size and good dispersibility. The composition, morphology, and particle size can be effectively tuned by changing the metal ratio, basicity, reaction time, and temperature of the LDH precursors. In addition, these spinel ferrites show high magnetic saturation values in the range 21.7–84.3 emu g−1, which maintain a higher level than the previously reported magnetic nanoparticles. Therefore, this work provides a facile approach for the design and fabrication of spinel ferrites with controllable nanostructure and improved magnetism, which could potentially be used in magnetic and biological fields, such as recording media, sensors, drug delivery, and intracellular imaging.