bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preventing over‐fitting in PLS calibration models of near‐infrared (NIR) spectroscopy data using regression coefficients
Authors: Gowen A. A. , Downey G. , Esquerre C. , O'Donnell C. P. 
Published: October 2010

AbstractSelection of the number of latent variables (LVs) to include in a partial least squares (PLS) model is an important step in the data analysis. Inclusion of too few or too many LVs may lead to, respectively, under or over‐fitting of the data and subsequently result in poor future model performance. One well‐known sign of over‐fitting is the appearance of noise in regression coefficients; this often takes the form of a reduction in apparent structure and the presence of sharp peaks with a high degree of directional oscillation, features which are usually estimated subjectively. In this work, a simple method for quantifying the shape and size of a regression coefficient is presented. This measure can be combined with an indicator of model bias (e.g. root mean square error) to aid in estimation of the appropriate number of LVs to include in a PLS model. The performance of the proposed method is evaluated on simulated and and real NIR spectroscopy datasets sets and compared with several existing methods. Copyright © 2010 John Wiley & Sons, Ltd.
Preparation and Investigation of Vitamin B6‐Derived Aminopyridinol Antioxidants
Authors: Serwa Remigiusz , Nam Tae‐gyu , Valgimigli Luca , Culbertson Sean , Rector Christopher L. , Jeong Byeong‐Seon , Pratt Derek A. , Porter Ned A. 
Published: October 2010

Abstract3‐Pyridinols bearing amine substitution para to the hydroxylic moiety have previously been shown to inhibit lipid peroxidation more effectively than typical phenolic antioxidants, for example, α‐tocopherol. We report here high‐yielding, large‐scale syntheses of mono‐ and bicyclic aminopyridinols from pyridoxine hydrochloride (i.e., vitamin B6). This approach provides straightforward, scaleable access to novel, potent, molecular scaffolds whose antioxidant properties have been investigated in homogeneous solutions and in liposomal vesicles. These molecular aggregates mimic cell membranes that are the targets of oxidative damage in vivo.
On the Trimerization of Cyanoacetylene: Mechanism of Formation of Tricyanobenzene Isomers and Laboratory Detection of Their Radio Spectra
Authors: Hopf Henning , Mlynek Cornelia , McMahon Robert J. , Menke Jessica L. , Lesarri Alberto , Rosemeyer Michael , Grabow Jens‐Uwe 
Published: October 2010

AbstractIn support of a deeper understanding of the chemistry of cyanoacetylene—a known constituent of planetary atmospheres and interstellar space—theoretical and experimental studies address the chemical mechanism of dimerization and trimerization, and provide high‐resolution rotational spectra of two of the trimeric products, 1,2,3‐ and 1,2,4‐tricyanobenzene. Analysis of the rotational spectra is particularly challenging because of quadrupolar coupling from three 14N nuclei. The laboratory rotational spectra provide the basis for future searches for these polar aromatic compounds in interstellar space by radio astronomy.
Oligo‐m‐phenyleneoxalamide Copper(II) Mesocates as Electro‐Switchable Ferromagnetic Metal–Organic Wires
Authors: Pardo Emilio , Ferrando‐Soria Jesús , Dul Marie‐Claire , Lescouëzec Rodrigue , Journaux Yves , Ruiz‐García Rafael , Cano Joan , Julve Miguel , Lloret Francesc , Cañadillas‐Delgado Laura , Pasán Jorge , Ruiz‐Pérez Catalina 
Published: October 2010

AbstractDouble‐stranded copper(II) string complexes of varying nuclearity, from di‐ to tetranuclear species, have been prepared by the CuII‐mediated self‐assembly of a novel family of linear homo‐ and heteropolytopic ligands that contain two outer oxamato and either zero (1 b), one (2 b), or two (3 b) inner oxamidato donor groups separated by rigid 2‐methyl‐1,3‐phenylene spacers. The X‐ray crystal structures of these CuIIn complexes (n=2 (1 d), 3 (2 d), and 4 (3 d)) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN2O2 and inner CuN4 chromophores. Two such nonplanar all‐syn bridging ligands 1 b–3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso‐helicate‐type architecture for 1 d–3 d. Variable‐temperature (2.0–300 K) magnetic susceptibility and variable‐field (0–5.0 T) magnetization measurements for 1 d–3 d show the occurrence of S=nSCu (n=2–4) high‐spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed CuII ions (SCu=1/2) through the two anti m‐phenylenediamidate‐type bridges (J values in the range of +15.0 to 16.8 cm−1). Density functional theory (DFT) calculations for 1 d–3 d evidence a sign alternation of the spin density in the meta‐substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7–2.2 nm. Cyclic voltammetry (CV) and rotating‐disk electrode (RDE) electrochemical measurements for 1 d–3 d show several reversible or quasireversible one‐ or two‐electron steps that involve the consecutive metal‐centered oxidation of the inner and outer CuII ions (SCu=1/2) to diamagnetic CuIII ones (SCu=0) at relatively low formal potentials (E values in the range of +0.14 to 0.25 V and of +0.43 to 0.67 V vs. SCE, respectively). Further developments may be envisaged for this family of oligo‐m‐phenyleneoxalamide copper(II) double mesocates as electroswitchable ferromagnetic ‘metal–organic wires’ (MOWs) on the basis of their unique ferromagnetic and multicenter redox behaviors.
The Dynamic Chemistry of Molecular Borromean Rings and Solomon Knots
Authors: Meyer Cari D. , Forgan Ross S. , Chichak Kelly S. , Peters Andrea J. , Tangchaivang Nicholas , Cave Gareth W. V. , Khan Saeed I. , Cantrill Stuart J. , Stoddart J. Fraser 
Published: October 2010

AbstractThe dynamic solution equilibria between molecular Borromean rings (BRs) and Solomon knots (SKs), assembled from transition metal‐templated macrocycles, consisting of exo‐bidentate bipyridyl and endo‐tridentate diiminopyridyl ligands, have been examined with respect to the choice of the metal template and reaction conditions employed in the synthesis of the metalated BRs, otherwise known as Borromeates. Three new Borromeates, their syntheses templated by CuII, CoII, and MnII, have been characterized extensively (two by X‐ray crystallography) to the extent that the metal centers in the assemblies have been shown to be distanced sufficiently from each other not to communicate. The solid‐state structure of the CoII–Borromeate reveals that six MeOH molecules, arranged in a [OH⋅⋅⋅O] hydrogen bonded, chair‐like conformation, are located within its oxophilic central cavity. When a mixture of CuII and ZnII is used as the source of templation, there exists a dynamic equilibrium, in MeOH at room temperature, between a mixed‐metal BR and a SK, from which the latter has been fractionally crystallized. By employing appropriate synthetic protocols with ZnII or CdII as the template, significant amounts of SKs are formed alongside BRs. Modified crystallization conditions resulted in the isolation of both an all‐zinc BR and an all‐zinc SK, crystals of which can be separated manually, leading to the full characterization of the all‐zinc SK by 1H NMR spectroscopy and X‐ray crystallography. This doubly interlocked [2]catenate has been identified retrospectively in recorded spectra, where it was attributed previously to a Borromeate with a ZnII cation coordinated to the oxophilic interior walls of the ensemble. Interestingly, these ZnII‐templated assemblies do not interconvert in MeOH at room temperature, indicating the significant influence of both the metal template and solvent on the solution equilibria. It would also appear that d10 metal ions favor SK formation—no evidence of CuII‐, CoII‐, or MnII‐templated SKs has been found, yet a 1:0.9 ratio of BR:SK has been identified by 1H NMR spectroscopy when CdII is used as the template.
Modulation of Photoswitching Profiles by 10,11‐Dialkoxymethyl Substituents in C2‐Symmetric Dibenzosuberane‐Based Helicenes
Authors: Chen Wen‐Ching , Lin Po‐Chiao , Chen Chien‐Hsiang , Chen Chien‐Tien 
Published: October 2010

AbstractA series of C2‐symmetric, 10,11‐disubstituted dibenzosuberane (DBS)‐based helicenes 6 a–c with a common 7‐bromo‐α‐tetralin‐based bottom fragment were synthesized. Their absolute stereochemistry was determined to be 10R,11R,P after reductive desulfurization of the corresponding (10R,11R,1′S)‐episulfides with complete stereospecificity. Photoisomerization of the diastereomerically pure (P)‐6 c in hexane led to virtually exclusive formation of the opposite M‐form diastereomer (P/M′, <1:>99) at 290 nm. The preferential return of (M′)‐6 c to (P)‐6 c was also achieved with high selectivity (P/M′, 90:10) at 330 nm. Molecular simulations of (P)‐6 c and (M′)‐6 c with both DBS conformations suggest that the selectivities of photoswitching are controlled by the conformation of the top DBS template as evidenced by their 1H NMR spectra. Doping 6 c into a nematic liquid crystal (E7) led to a cholesteric mesophase with modulated pitches, reversible helical senses, and with a switch memory of ternary logic.
Dynamic spatiotemporal gene expression in embryonic mouse thalamus
Authors: Suzuki‐Hirano Asuka , Ogawa Masaharu , Kataoka Ayane , Yoshida Aya C. , Itoh Daisuke , Ueno Masaki , Blackshaw Seth , Shimogori Tomomi 
Published: October 2010

AbstractThe anatomy of the mammalian thalamus is characterized by nuclei, which can be readily identified in postnatal animals. However, the molecular mechanisms that guide specification and differentiation of neurons in specific thalamic nuclei are still largely unknown, and few molecular markers are available for most of these thalamic subregions at early stages of development. We therefore searched for patterned gene expression restricted to specific mouse thalamic regions by in situ hybridization during the onset of thalamic neurogenesis (embryonic [E] days E10.5–E12.5). To obtain correct regional information, we used Shh as a landmark and compared spatial relationships with the zona limitans intrathalamica (Zli), the border of the p2 and p3 compartments of the diencephalon. We identified genes that are expressed specifically in the ventricular zone of the thalamic neuroepithelium and also identified a number of genes that already exhibited regional identity at E12.5. Although many genes expressed in the mantle regions of the thalamus at E12.5 showed regionally restricted patterns, none of these clearly corresponded to individual thalamic nuclei. We next examined gene expression at E15.5, when thalamocortical axons (TCAs) project from distinct regions of the thalamus and reach their targets in the cerebral cortex. Regionally restricted patterns of gene expression were again seen for many genes, but some regionally bounded expression patterns in the early postnatal thalamus had shifted substantially by E15.5. These findings reveal that nucleogenesis in the developing thalamus is associated with selective and complex changes in gene expression and provide a list of genes that may actively regulate the development of thalamic nuclei. J. Comp. Neurol. 519:528–543, 2011. © 2010 Wiley‐Liss, Inc.
A molecular mechanism that regulates medially oriented axonal growth of upper layer neurons in the developing neocortex
Authors: Zhao Hong , Maruyama Takuro , Hattori Yuki , Sugo Noriyuki , Takamatsu Hyota , Kumanogoh Atsushi , Shirasaki Ryuichi , Yamamoto Nobuhiko 
Published: October 2010

AbstractDuring development, cortical neurons extend axons to their targets based on their laminar locations and cell types. Here we studied the molecular mechanism that regulates medially oriented axonal growth of upper layer neurons in the developing mouse cortex. Upper layer neurons were labeled with enhanced yellow fluorescent protein (EYFP) by in utero electroporation at E15.5. Cortical slices containing EYFP‐labeled cells were dissected at E16, when axonal outgrowth from upper layer neurons is not initiated, and were cultured in an organotypic manner. After 3 days in culture, most labeled cells were found to extend axons medially in the same fashion as those observed in vivo. This oriented growth was disrupted when the lateral side of the cortical slice was removed, indicating that a laterally located repellent is involved in the medially oriented growth. Strikingly, the medially directed growth within the slices was reduced in the medium containing Semaphorin3A (Sema3A) or soluble form of Neuropilin‐1 (Npn1), a receptor for Sema3A. Importantly, we found that Sema3A was expressed in a gradient from lateral‐high to medial‐low within the cortex, and callosal axons originating from upper layer neurons uniquely expressed Npn1. Consistent with these findings, ectopically expressed Sema3A repelled medially oriented elongation of upper layer cell axons in vivo. These results therefore suggest the operation of a repulsive mechanism for medially oriented axon growth of upper layer neurons, and further point to a role for a gradient expression of Sema3A in this directional axon growth along the mediolateral axis within the neocortex. J. Comp. Neurol. 519:834–848, 2011. © 2010 Wiley‐Liss, Inc.
Complexation of Phenol and Thiophenol by Amine N‐Oxides: Isothermal Titration Calorimetry and ab Initio Calculations
Authors: Cuypers Ruud , Murali Sukumaran , Marcelis Antonius T. M. , Sudhölter Ernst J. R. , Zuilhof Han 
Published: October 2010

AbstractTo develop a new solvent‐impregnated resin (SIR) system for removal of phenols from water, the complex formation of dimethyldodecylamine N‐oxide (DMDAO), trioctylamine N‐oxide (TOAO), and tris(2‐ethylhexyl)amine N‐oxide (TEHAO) with phenol (PhOH) and thiophenol (PhSH) is studied. To this end we use isothermal titration calorimetry (ITC) and quantum chemical modeling (on B3LYP/6‐311G(d,p)‐optimized geometries: B3LYP/6‐311+G(d,p), B3LYP/6‐311++G(2d,2p), MP2/6‐311+G(d,p), and spin component scaled (SCS) MP2/6‐311+G(d,p); M06‐2X/6‐311+G(d,p)//M06‐2X/6‐311G(d,p), MP2 with an extrapolation to the complete basis set limit (MP2/CBS), as well as CBS‐Q). The complexes are analyzed in terms of structural (e.g., bond lengths) and electronic elements (e.g., charges). Furthermore, complexation and solvent effects (in benzene, toluene, and mesitylene) are investigated by ITC measurements, yielding binding constants K, enthalpies ΔH0, Gibbs fre energies ΔG0, and entropies ΔS0 of complex formation, and stoichiometry N. The ITC measurements revealed strong 1:1 complex formation between both DMDAO–PhOH and TOAO–PhOH. The binding constant (K=1.7–5.7×104 M−1) drops markedly when water‐saturated toluene was used (K=5.8×103 M−1), and π–π interaction with the solvent is shown to be relevant. Quantum mechanical modeling confirms formation of stable 1:1 complexes with linear hydrogen bonds that weaken on attachment of electron‐withdrawing groups to the amine N‐oxide moiety. Modeling also showed that complexes with PhSH are much weaker than those with PhOH, and in fact too weak for ITC determination. CBS‐Q incorrectly predicts equal or even higher binding enthalpies for PhSH than for PhOH, which invalidates it as a benchmark for other calculations. Data from the straightforward SCS‐MP2 method without counterpoise correction show very good agreement with the MP2/CBS values.
Fluorescence Blinking of the RC–LH1 Complex from Rhodopseudomonas palustris
Authors: Unterkofler Sarah , Pflock Tobias , Southall June , Cogdell Richard J. , Köhler Jürgen 
Published: October 2010

AbstractWe investigate fluorescence blinking of individual RC–LH1 (reaction‐centre–light‐harvesting 1) complexes from the photosynthetic purple bacterium Rhodopseudomonas palustris. For both the on‐ and off‐periods the telegraph‐like intermittency of the fluorescence intensity follows power‐law statistics with exponents between 1 and 2. Yet, this behaviour was only observed for a small fraction of the complexes studied. We argue that the majority of the complexes reside in a prolonged on‐state, due to a mechanism that is similar to the Coulomb blockade in semiconductor quantum dots, and which results here from the photoinduced charges located within the RC upon photoexcitation of the LH1 antenna.
IFDAT—International forum for drug and alcohol testing, 12–14 April 2010, Barcelona, Spain
Authors: Kenney JD Josephine Elizabeth , Björklöv Per 
Published: October 2010

AbstractThe second programme of its kind globally, the highly successful, collaborative, productive and energizing IFDAT—International Forum for Drug and Alcohol Testing, was held in Barcelona, Spain, from 12–14 April. IFDAT was attended by over 100 delegates, conference sponsors and exhibitors from the international workplace drug and alcohol testing industry. Representing over 20 countries, the delegate professionals, speakers, and presenters included employers, service agents, an international publisher, and workplace testing suppliers. The purpose of the forum was to exchange knowledge, learn about new technology, and support the evolution and growth of the emerging international workplace drug and alcohol testing industry. This purpose was accomplished. Delegates from around the globe exchanged their experiences and thoughts about effective workplace drug testing programmes over two days of intensive presentations and panel discussions. The presenters and panelists included drug and alcohol testing professionals, authorities, and intellectuals from around the world.IFDAT conferences are planned for every 18 months, and the next Forum, to be held in Houston, Texas, USA is in the planning process for 2011. Copyright © 2010 John Wiley & Sons, Ltd.
Drug metabolism in the horse: a review
Authors: Scarth James P. , Teale Phil , Kuuranne Tiia 
Published: October 2010

AbstractA detailed understanding of equine drug metabolism is important for detection of drug abuse in horseracing and also in veterinary drug development and practice. To date, however, no comprehensive review of equine drug metabolism has been published.The majority of literature regarding equine drug metabolite profiles is derived from sports drug detection research and is generally targeted at detecting marker metabolites of drug abuse. However, the bulk of the literature on equine drug metabolism enzymology is derived from veterinary studies aimed at determining the molecular basis of metabolism. In this article, the phase 1 and 2 metabolisms of seven of the most important classes of drugs monitored in horseracing are reviewed, including: anabolic‐androgenic steroids (AAS), β2‐agonists, stimulants, sedatives/tranquilizers, local anesthetics, non‐steroidal anti‐inflammatory analgesics (NSAIDS)/cyclooxygenase‐2 (COX‐2) inhibitors, and opioid analgesics. A summary of the literature relating to the enzymology of drug metabolism in this species is also be presented.The future of equine drug metabolism in the area of doping research will be influenced by several factors, including: a possible move towards the increased use of blood and other alternative testing matrices; the development of assays based on intact drug conjugates; the increasing threat of ‘designer’ and herbal‐ based products; advances in the use ofin vitrotechnologies; the increased use of liquid‐chromatography/high‐resolution mass spectrometry; and the possibility of screening using ‘omics’ approaches. Also, the recent cloning of a range of equine cytochrome P450 (CYP) enzymes opens up the potential for carrying out more detailed mechanistic pharmacological and toxicological veterinary studies. Copyright © 2010 John Wiley & Sons, Ltd.
Stable isotope ratio profiling of testosterone preparations
Authors: Cawley Adam , Collins Michael , Kazlauskas Rymantas , Handelsman David J , Heywood Robert , Longworth Mitchell , Arenas‐Queralt Andrea 
Published: October 2010

AbstractGas chromatography‐combustion‐isotope ratio mass spectrometry (GC‐C‐IRMS) is the preferred method of confirming the administration of exogenous testosterone by athletes. This relies on synthetic testosterone preparations being depleted in 13C compared to natural testosterone. There is concern, however, about the existence of synthetic testosterone products that are unexpectedly 13C‐enriched and which may allow athletes to circumvent the current GC‐C‐IRMS test. Further to the reported studies of legitimate pharmaceutical‐grade testosterone products, a detailed analysis of seized materials from border‐level seizures was required to obtain intelligence concerning trends in ‘black market’ testosterone manufacture and distribution. The sample set collected for this study between 2006 and 2009 inclusive provided a δ13C range (n = 266) of − 22.9‰ to − 32.6‰ with mean and median values of − 28.4‰ and − 28.6‰, respectively. Within this distribution there were 24 samples (9%) confirmed to have δ13C values in the range reported for endogenous urinary steroid metabolites (≥− 25.8‰). The benefit of δ13C profiling for testosterone preparations was demonstrated by the ability to identify specific seized products that can be target tested for future intelligence purposes.In addition, the potential of stable hydrogen isotope ratio (2H/1H; δ2H) discrimination to complement δ13C analysis was investigated. Methodologies for the determination of δ2H values by gas chromatography‐thermal conversion‐isotope ratio mass spectrometry (GC‐TC‐IRMS) were developed to provide a δ2H range (n = 173) of − 177‰ to − 268‰ with mean and median values of − 231‰ and − 234‰, respectively. Copyright © 2010 John Wiley & Sons, Ltd.
Donor‐Functionalised Expanded Ring N‐Heterocyclic Carbenes: Highly Effective Ligands in Ir‐Catalysed Transfer Hydrogenation
Authors: Binobaid Abeer , Iglesias Manuel , Beetstra Dirk , Dervisi Athanasia , Fallis Ian , Cavell Kingsley J. 
Published: October 2010

AbstractThe performances of a number of RhI and IrI complexes of type [M(NHC)(COD)Cl] in the transfer hydrogenation of ketones were tested under a variety of reaction conditions, and with a variety of substrates, allowing comparison of Rh‐ and Ir‐NHC complexes, and also comparison of the influence of the NHC ligand on catalytic performance. Notably, of the RhI and IrI complexes with symmetrically substituted NHCs only those bearing cyclohexyl substituents were active, with RhI complexes of saturated 5‐, 6‐ and 7‐NHCs with N‐Mes substituents, [Rh(5,6,7‐Mes)(COD)Cl], showing no activity in transfer hydrogenation under the test conditions. RhI and IrI complexes of unsymmetrical o‐methoxyphenyl donor‐functionalised NHCs (df‐NHC) with differing carbene ring sizes were also tested in transfer hydrogenations, with the RhI complexes displaying no catalytic activity. However, the corresponding df‐NHC IrI complexes were found to be extremely effective catalysts. Catalyst tests also demonstrated the excellent stability of these complexes.