bluuebunny/crossref_metadata_2025 huggingface dataset:
Le jugement des enseignants sur la préparation scolaire des enfants à la maternelle durant les années 1990 et 2000
Authors: Lapointe Pierre , Japel Christa , Belleville Maude
Published: March 2014

Cette étude illustre la diversité des modes d’adaptation des enfants à une période critique de leur développement. La préparation scolaire de 10 867 enfants a été évaluée par des enseignants de la maternelle en 1998 et 2005. L’analyse typologique distingue quatre profils d’enfants : mature, en difficulté d’adaptation, en difficulté d’apprentissage et à risque. Le jugement des enseignants varie selon les caractéristiques personnelles, familiales et scolaires des enfants. L’examen comparatif d’évaluations réalisées auprès d’enfants de milieux socioéconomiques défavorisés durant les années 1998 et 2005 tend à démontrer la stabilité de ces profils de préparation scolaire. Les résultats de cette étude sont discutés en regard des travaux sur le développement de l’enfant en milieu scolaire.
L’innovation impossible comme objet sociologique. Le cas de l’implantation d’un dispositif intégrateur des services aux personnes âgées en perte d’autonomie
Authors: Couturier Yves , Etheridge Francis
Published: March 2014

L’innovation serait souvent décevante et empreinte d’usages stratégiques, voire idéologiques, plus ou moins questionnables. Le présent article propose de jeter un regard sociologique sur l’innovation, en tentant de donner du sens à ces déceptions et critiques. L’innovation déçoit souvent, parce qu’elle est impossible, au sens de la célèbre phrase de Freud, parlant de ces métiers pour lesquels l’efficacité est difficile, mais dont la nécessité est pourtant grande. Étudier l’innovation exige donc de l’observer avec d’autres yeux que ceux du succès et de l’efficacité, en cherchant à comprendre ses différents effets réels, par-delà sa capacité à rencontrer ses propres objectifs. Cette réflexion se fera à partir de l’évocation de la diffusion d’une très vaste innovation, soit l’implantation d’un dispositif visant l’intégration des services pour les personnes âgées en perte d’autonomie au Québec. Nous verrons que l’écart entre le projet porté par cette innovation et la réalité de son implantation est grand, mais que malgré cet écart, elle a fait bouger les lignes de façon importante en favorisant un changement important dans la manière de concevoir les services de santé et sociaux.
L’utilité de la sociologie pour comprendre le passage de l’imaginaire à l’innovation dans les organisations
Authors: Michaud Thomas
Published: March 2014

La sociologie de l’imaginaire contribue à mieux comprendre le processus d’innovation dans les organisations et les entreprises. Cette approche consiste à étudier de quelle manière l’imaginaire est géré par les individus et les groupes, pour devenir un élément de productivité, ou un frein à l’innovation. Il est par exemple établi de quelle manière l’imaginaire peut constituer un exutoire cognitif particulièrement utile dans les structures technoscientifiques pour éviter des problèmes dans la gestion du délire logique qui en émane. L’imaginaire se retrouve à toutes les phases du processus d’innovation, chez les scientifiques chargés d’inventer de nouveaux objets, mais aussi dans les considérations des experts en marketing, chargés de commercialiser les innovations. La sociologie est utilisée pour mieux comprendre l’innovation, et les rouages imaginaires qui y participent.
Low Temperature 2D Electron Diamagnetism in Crossed Electric Fields
Authors: Harrison Michael J.
Published: March 2014

The energy level spectrum of a 2D electron system placed in crossed uniform magnetic and non-uniform reflection-symmetric electric fields has been calculated. The electric fields are those generated by applying equal voltages to symmetrically shaped electrodes symmetrically placed perpendicular to the plane of the 2D electron gas. Semiclassical methods have been used to obtain expressions for the energy levels, which are then utilized to study the zero temperature variation of diamagnetism with magnetic field.
Comparison of the extended solar minimum of 2006–2009 with the Spoerer, Maunder, and Dalton Grand Minima in solar activity in the past
Authors: McCracken K. G. , Beer J.
Published: March 2014

We use cosmic radiation records (neutron monitor and the cosmogenic radionuclides, 10Be and 14C) as a proxy to compare the solar activity during the extended solar minimum 2006–2009, with that during the Grand Solar Minima and Maxima that occurred between 1391 and 2010. The inferred cosmic ray intensities during the Spoerer, Maunder, and Dalton Grand Minima were significantly greater than those during 2006–2009. The onset phases of the three Grand Minima extended over between two and five Schwabe (sunspot) cycles, the cosmic ray intensity at the Schwabe minima increasing from a value approximating that of 2006–2009, to substantially higher values later in the Grand Minimum. The minimum estimated strengths of the heliospheric magnetic field near Earth during the Grand Minima were 2.4 nT (Spoerer), <2.0 nT (Maunder), and 2.6 nT (Dalton), compared to 3.9 nT in 2009. We conclude that the periods of highest solar activity during the Maunder Minimum approximated those near the sunspot minima between 1954 and 1996. The average ratio of the maximum to minimum estimated HMF in the six Schwabe cycles in the Maunder Minimum is 1.54 (range 1.30–1.85) compared to 1.52 (1.31–1.63) for the modern epoch suggesting similar operation of the solar dynamo in both intervals. The onset phase of the Maunder Minimum extending over five Schwabe cycles, and the large increase in cosmic ray flux (and decrease in estimated heliospheric magnetic field), leads us to speculate that the magnetohydrodynamic amplification in the solar dynamo exhibits a relaxation time well in excess of the 11 year period of the Schwabe cycle.
Rapid rotation of normal faults due to flexural stresses: An explanation for the global distribution of normal fault dips
Authors: Olive Jean‐Arthur , Behn Mark D.
Published: March 2014

We present a mechanical model to explain why most seismically active normal faults have dips much lower (30–60°) than expected from Anderson‐Byerlee theory (60–65°). Our model builds on classic finite extension theory but incorporates rotation of the active fault plane as a response to the buildup of bending stresses with increasing extension. We postulate that fault plane rotation acts to minimize the amount of extensional work required to sustain slip on the fault. In an elastic layer, this assumption results in rapid rotation of the active fault plane from ~60° down to 30–45° before fault heave has reached ~50% of the faulted layer thickness. Commensurate but overall slower rotation occurs in faulted layers of finite strength. Fault rotation rates scale as the inverse of the faulted layer thickness, which is in quantitative agreement with 2‐D geodynamic simulations that include an elastoplastic description of the lithosphere. We show that fault rotation promotes longer‐lived fault extension compared to continued slip on a high‐angle normal fault and discuss the implications of such a mechanism for fault evolution in continental rift systems and oceanic spreading centers.
Autofluidization of pyroclastic flows propagating on rough substrates as shown by laboratory experiments
Authors: Chedeville Corentin , Roche Olivier
Published: March 2014

This study investigates the influence of the substrate surface roughness on the emplacement mechanisms of pyroclastic flows. We carried out laboratory experiments on gravitational flows generated from the release of initially fluidized or nonfluidized columns of fine particles (diameter d = 0.08 mm) in a horizontal channel. The roughness of the channel base was uniform in each experiment, created by gluing particles of diameter d0 = 0.08 to 6 mm to the base. Other things being equal, the flow runout distance increased with the channel base roughness (d0) to a maximum of about twice that of flows on a smooth substrate when d0 = 1.5–3 mm, before decreasing moderately at higher roughness values of d0 = 6 mm. Long runout originated mainly during the late stages of emplacement as flow deceleration was strongly reduced at high substrate roughness. This was caused by (partial) autofluidization due to an upward air flux escaping from the substrate interstices in which flow particles settled. Autofluidization was evidenced by high pore fluid pressure measurements at the base of initially nonfluidized flows and also by reduced flow runout when the interstices were initially partially filled so that less air was available. Furthermore, the runout distance of flows of large particles (d = 0.35 mm), which could not be fluidized by the ascending air flux, was independent of the substrate roughness. This study suggests that autofluidization caused by air escape from the interstices of a rough substrate is one important mechanism to explain the common long runout distance of pyroclastic flows even on subhorizontal topographies.
Branched dart leaders preceding lightning return strokes
Authors: Stolzenburg Maribeth , Marshall Thomas C. , Karunarathne Sumedhe , Karunarathna Nadeeka , Orville Richard E.
Published: March 2014

This study describes the occurrence of branches in lightning dart leaders, based on data acquired in Florida using a high‐speed video camera and electric field change sensors. More than half (57%) of 72 flashes with analyzable dart leaders show at least one successful branched dart leader (BDL), and nine flashes have two successful BDLs. Overall, 18% of 282 visible successful dart leaders are branched. Most (42 of 50) cases of BDLs occur in the first dart leader after a stepped leader/return stroke sequence, and the data indicate that 55% of first dart leaders are visibly branched. Compared to first dart leaders in the 31 flashes without any branched dart leaders, BDLs tend to follow stepped leader/return strokes with significantly larger average peak currents (−31.3 versus −20.6 kA) and shorter average interstroke intervals (71.94 versus 94.64 ms). Average peak current of BDL strokes is 62% larger (−17.8 versus −11 kA) than that for unbranched first dart leader strokes. Branched dart leaders generally travel in the some of the most recently used lightning channels, but they are not always within the main channel of the prior return stroke. Successful BDLs may dart all the way to ground when in a prior stroke channel, or they may become stepped leaders when they reach the lower end of the prior stroke branch. Electric field change data for all the BDL cases exhibit an erratic pulse character for at least part of the leader duration; in some cases, the erratic character ends when the branches vanish.
Cauchy data requirement of the inverse problem of the mean age equation
Authors: Nassar Mohamed K. , Ginn Timothy R.
Published: March 2014

A classical theoretical inverse problem in groundwater hydraulics is the calibration of a heterogeneous isotropic hydraulic conductivity field using known hydraulic head data at each point in the domain. It has been long known that a necessary condition for the uniqueness of the solution to this theoretical inverse problem is the Cauchy data, i.e., the hydraulic conductivity values (or, equivalently, flux) along a line crossing all streamtubes in the entire domain. This result has been cited in identifying the value of boundary flux data in practical inverse problems, although in general such data are generally not available. In this work, we show that groundwater mean age data replace this Cauchy data requirement.
A modeling approach reveals differences in evapotranspiration and its partitioning in two semiarid ecosystems in Northwest Mexico
Authors: Méndez‐Barroso Luis A. , Vivoni Enrique R. , Robles‐Morua Agustin , Mascaro Giuseppe , Yépez Enrico A. , Rodríguez Julio C. , Watts Christopher J. , Garatuza‐Payán Jaime , Saíz‐Hernández Juan A.
Published: March 2014

Seasonal vegetation changes during the North American monsoon play a major role in modifying water, energy, and momentum fluxes. Nevertheless, most models parameterize plants as a static component or with averaged seasonal variations that ignore interannual differences and their potential impact on evapotranspiration (ET) and its components. Here vegetation parameters derived from remote sensing data were coupled with a hydrologic model at two eddy covariance (EC) sites with observations spanning multiple summers. Sinaloan thornscrub (ST) and Madrean woodland (MW) sites, arranged at intermediate and high elevations along mountain fronts in northwest Mexico, occupy specific niches related to climate conditions and water availability that are poorly understood. We found that simulations with a dynamic representation of vegetation greening tracked well the seasonal evolution of observed ET and soil moisture (SM). A switch in the dominant component of ET from soil evaporation (E) to plant transpiration (T) was observed for each ecosystem depending on the timing and magnitude of vegetation greening that is directly tied to rainfall characteristics. Differences in vegetation greening at the ST and MW sites lead to a dominance of transpiration at ST (T/ET = 57%), but evaporation‐dominant conditions at MW (T/ET = 19%). Peak transpiration occurred at 5 and 20 days after the full canopy development in the ST and MW sites, respectively. These results indicate that evapotranspiration timing and partitioning varies considerably in the two studied ecosystems in accordance with different modes of vegetation greening. Intermediate‐elevation ecosystems follow an intensive water use strategy with a rapid and robust transpiration response to water availability. In contrast, higher elevation sites have delayed and attenuated transpiration, suggesting an extensive water use strategy persisting beyond the North American monsoon.
Suppression of Void Formation in Si0.5Ge0.5 Alloy Nanowire during Ni Germanosilicidation
Authors: Li Yida , Buddharaju Kavitha , Wang Xin‐Peng , Lee Sung‐Joo , Thong Thiam‐Leong
Published: March 2014

The growth mechanism of Ni‐germanosilicide in Si0.5Ge0.5 NW with and without silicon dioxide shell encapsulation was investigated using transmission electron microscope imaging with in situ annealing of SiGe NW array samples capped with Ni. At 200 and 400 °C, the interfacial reaction is minimal while at 600 °C, we can observe the gradual formation of a thin Ni‐germanosilicide filament for the unconstrained SiGe NW. This observation is concomitant with material loss from the sides of the SiGe NW, which eventually leads to void formation. Energy dispersive X‐ray spectroscopy analysis along the SiGe NW shows that Ge atoms out‐diffused from the NW toward the Ni source during annealing. Excessive out‐diffusion of Ge atoms and void formation are shown to be retarded in the encapsulated SiGe NW with compressive stress.
Self‐Aligned Single‐Crystal Graphene Grains
Authors: Geng Dechao , Luo Birong , Xu Jie , Guo Yunlong , Wu Bin , Hu Wenping , Liu Yunqi , Yu Gui
Published: March 2014

The precisely controllable growth of self‐aligned single‐crystal graphene grains on liquid Cu surface by ambient pressure chemical vapor deposition is reported. Large scale monolayer graphene arrays are modulated by varying growth conditions such as flow rate of carbon source, growth temperature, and growth time. Further, bilayer graphene grains are also controllably prepared under optimized growth conditions. The self‐alignment mechanism of graphene is also studied and a growth model is proposed to explain that process involving surface tension of liquid phase. In all, the growth mechanism of graphene arrays is firstly probed and the grown graphene arrays show reasonable mobility and high current density, posing great potential for graphene‐based electronics.
Catalytic Oxidation of C(sp3)H Bonds Induced by a Radical Cation Salt: Construction of 1,4‐Dihydropyridines Using a Fragment‐Reassembly Strategy
Authors: Jia Xiaodong , Wang Yaxin , Peng Fangfang , Huo Congde , Yu Liangling , Liu Jing , Wang Xicun
Published: March 2014

A fragment‐reassembly strategy was applied to the construction of 1,4‐dihydropyridines and phosphorus‐substituted 1,4‐dihydropyridines under catalytic radical cation salt‐induced C(sp)3H functionalization of glycine derivatives. Mechanistic studies show that domino C(sp)3H bond oxidation and CN bond cleavage reactions are involved.

magnified image
Fine‐tuning the Local Symmetry to Attain Record Blocking Temperature and Magnetic Remanence in a Single‐Ion Magnet
Authors: Ungur Liviu , Le Roy Jennifer J. , Korobkov Ilia , Murugesu Muralee , Chibotaru Liviu F.
Published: March 2014

Remanence and coercivity are the basic characteristics of permanent magnets. They are also tightly correlated with the existence of long relaxation times of magnetization in a number of molecular complexes, called accordingly single‐molecule magnets (SMMs). Up to now, hysteresis loops with large coercive fields have only been observed in polynuclear metal complexes and metal‐radical SMMs. On the contrary, mononuclear complexes, called single‐ion magnets (SIM), have shown hysteresis loops of butterfly/phonon bottleneck type, with negligible coercivity, and therefore with much shorter relaxation times of magnetization. A mononuclear ErIII complex is presented with hysteresis loops having large coercive fields, achieving 7000 Oe at T=1.8 K and field variation as slow as 1 h for the entire cycle. The coercivity persists up to about 5 K, while the hysteresis loops persist to 12 K. Our finding shows that SIMs can be as efficient as polynuclear SMMs, thus opening new perspectives for their applications.
A Chiral Thioxanthone as an Organocatalyst for Enantioselective [2+2] Photocycloaddition Reactions Induced by Visible Light
Authors: Alonso Rafael , Bach Thorsten
Published: March 2014

Thioxanthone 1, which was synthesized in a concise fashion from methyl thiosalicylate, exhibits a significant absorption in the visible light region. It allows for an efficient enantioselective catalysis of intramolecular [2+2] photocycloaddition reactions presumably by triplet energy transfer.
K4[PbSe4]⋅en⋅NH3: A Non‐Oxide, Non‐Halide Inorganic Lead(IV) Compound
Authors: Thiele Günther , Krüger Thomas , Dehnen Stefanie
Published: March 2014

The first inorganic lead(IV) compound without oxygen, nitrogen or halogen ligands attached to the lead atom was obtained as the potassium salt of the tetraselenidoplumbate(IV) anion [PbIVSe4]4−. It is stable under inert conditions which may enable the transfer of the chemistry of chalcogenidogermanate(IV) or chalcogenidostannate(IV) materials, to the lead homologues.
Synthesis of Novel Purine‐Based Coxsackievirus Inhibitors Bearing Polycylic Substituents at the N‐9 Position
Authors: Dejmek Milan , Šála Michal , Plačková Pavla , Hřebabecký Hubert , Mascarell Borredà Laura , Neyts Johan , Dračínský Martin , Procházková Eliška , Jansa Petr , Leyssen Pieter , Mertlíková‐Kaiserová Helena , Nencka Radim
Published: March 2014

The synthesis of a novel library of purine derivatives bearing various bicyclic and polycylic substituents at the N‐9 position is described. The series includes norbornanes, bicyclo[2.2.2]octanes, and bicyclo[3.2.1]octanes attached at the bridgehead position as well as bicyclo[3.1.1]heptanes, tetrahydro‐1‐naphthalenes, and adamantanes bonded either directly or via a linear chain to the 6‐chloropurine nucleobase. A number of prepared derivatives exerted significant activity against the enterovirus. Despite attempts to correlate the activity against picornaviruses with their phosphatidylinositol 4‐kinase KIIIβ inhibitory activity, it is clear that the inhibition of this host factor cannot explain the observed antiviral potency.
More on functional data analysis and other aspects in OODA
Authors: Ugarte Maria D. , Aguilera Ana M.
Published: March 2014

This is a discussion of the paper “Overview of object oriented data analysis” by J. Steve Marron and Andrés M. Alonso.
Characterization of an Environmental DNA‐Derived Gene Cluster that Encodes the Bisindolylmaleimide Methylarcyriarubin
Authors: Chang Fang‐Yuan , Brady Sean F.
Published: March 2014

Bisindolylmaleimides represent a naturally occurring class of metabolites that are of interest because of their protein kinase inhibition activity. From a metagenomic library constructed with soil DNA, we identified the four gene mar cluster, a bisindolylmaleimide gene cluster that encodes for methylarcyriarubin (1) production. Heterologous expression of the mar gene cluster in E. coli revealed that the Rieske dioxygenase MarC facilitates the oxidative decarboxylation of a chromopyrrolic acid (CPA) intermediate to yield the bisindolylmaleimide core. The characterization of the mar cluster defines a new role for CPA in the biosynthesis of structurally diverse bacterial tryptophan dimers.
Polymer‐Stabilized Palladium Nanoparticles for the Chemoselective Transfer Hydrogenation of α,β‐Unsaturated Carbonyls: Single‐Step Bottom‐Up Approach
Authors: Mahato Sanjit K. , Ul Islam Rafique , Acharya Chiranjit , Witcomb Michael J. , Mallick Kaushik
Published: March 2014

Polypyrrole stabilised palladium nanoparticles show good catalytic efficiency for the chemoselective transfer hydrogenation of α,β‐unsaturated carbonyl compounds. The catalyst is very specific and selectively hydrogenates the olefins or acetylenes only, without affecting the carbonyl moiety, with an excellent yield of products for a wide range of substrates.
Structures and Properties of Molecular Torsion Balances to Decipher the Nature of Substituent Effects on the Aromatic Edge‐to‐Face Interaction
Authors: Gardarsson Haraldur , Schweizer W. Bernd , Trapp Nils , Diederich François
Published: March 2014

Various recent computational studies initiated this systematic re‐investigation of substituent effects on aromatic edge‐to‐face interactions. Five series of Tröger base derived molecular torsion balances (MTBs), initially introduced by Wilcox and co‐workers, showing an aromatic edge‐to‐face interaction in the folded, but not in the unfolded form, were synthesized. A fluorine atom or a trifluoromethyl group was introduced onto the edge ring in ortho‐, meta‐, and para‐positions to the CH group interacting with the face component. The substituents on the face component were varied from electron‐donating to electron‐withdrawing. Extensive X‐ray crystallographic data allowed for a discussion on the conformational behavior of the torsional balances in the solid state. While most systems adopt the folded conformation, some were found to form supramolecular intercalative dimers, lacking the intramolecular edge‐to‐face interaction, which is compensated by the gain of aromatic π‐stacking interactions between four aryl rings of the two molecular components. This dimerization does not take place in solution. The folding free enthalpy ΔGfold of all torsion balances was determined by 1H NMR measurements by using 10 mM solutions of samples in CDCl3 and C6D6. Only the ΔGfold values of balances bearing an edge‐ring substituent in ortho‐position to the interacting CH show a steep linear correlation with the Hammett parameter (σmeta) of the face‐component substituent. Thermodynamic analysis using van′t Hoff plots revealed that the interaction is enthalpy‐driven. The ΔGfold values of the balances, in addition to partial charge calculations, suggest that increasing the polarization of the interacting CH group makes a favorable contribution to the edge‐to‐face interaction. The largest contribution, however, seems to originate from local direct interactions between the substituent in ortho‐position to the edge‐ring CH and the substituted face ring.
Saddlepoint approximations for rank‐invariant permutation tests and confidence intervals with interval‐censoring
Authors: Abd‐Elfattah Ehab , Butler Ronald
Published: March 2014

Interval‐censored data occur when subjects are assessed by using regular follow‐up. In such instances, we consider rank‐invariant permutation tests to test the significance of a treatment versus a control. For a wide class of such tests, which includes the Peto & Peto class, we present saddlepoint approximations for the exact permutation mid‐P‐values which achieve extremely small relative errors. The speed and stability of these saddlepoint computations make them practicable for inverting the permutation tests and we compute nominalconfidence intervals for the treatment effect. Such confidence intervals are of substantial clinical importance since, more than simply stating the level of statistical significance, they quantify the significant benefit of the treatment by providing a confidence interval for the percentage increase in mean (or median) treatment survival time as compared to control. Our methodology makes heavy use of nonparametric MLEs (NPMLEs) for survival functions and some limitations of existing algorithms, such as the hybrid ICM algorithm, are noted and accommodated.The Canadian Journal of Statistics42: 308–324; 2014 © 2014 Statistical Society of Canada
Paul Harteck (1902–1985) – führender Physikochemiker des letzten Jahrhunderts
Authors: Stegmann Annalena , Habekost Achim
Published: March 2014

Der Nachweis der Umwandlung von ortho/para Wasserstoff, die Entdeckung des Tritiums in der Atmosphäre, die Herstellung von Schwerem Wasser, der Bau von Isotopentrennanlagen und Versuche zur Uran‐Kettenreaktion, die Entwicklungen auf dem Gebiete der Photochemie – all diese Arbeiten gehen auf den österreichisch‐deutschen Physikochemiker Paul Harteck zurück. Harteck war zudem im Uranverein einer derjenigen, der die experimentelle Entwicklung einer „Uranmaschine“ am intensivsten voran trieb.
Management of Patients With Atrial Fibrillation by Primary‐Care Physicians in Germany: 1‐Year Results of the ATRIUM Registry
Authors: Kirchhof Paulus , Schmalowsky Janine , Pittrow David , Rosin Ludger , Kirch Wilhelm , Wegscheider Karl , Meinertz Thomas ,   for the ATRIUM Study Group
Published: March 2014

Background

Patients with atrial fibrillation (AF) in Germany are often managed jointly by primary‐care physicians in cooperation with cardiologists. We aimed to investigate the management and 1‐year outcomes of AF patients in this setting.

Hypothesis

We set out to describe the current management of AF patients in primary care settings in Germany.

Methods

Observational registry with 1‐year follow‐up, performed by a representative, randomly selected sample of 781 primary‐care physicians in Germany.

Results

Of 3781 patients with electrocardiographically documented AF, 3163 patients (age 71.9 ± 9.2 years, 57.9% males) were followed for 1 year; 28.4% had paroxysmal, 27.0% persistent, and 43.3% permanent AF. Comorbid conditions were common (mean CHA2DS2‐VASc score 3. 8 ± 1.7). Rhythm‐control therapy was used in 16.4%. Although oral anticoagulation was often used (82.7% at baseline), stroke rate during follow‐up was high (2.7% stroke, 3.0% transient ischemic attack). Despite a long duration of AF (mean duration 61 months at enrollment), 18.5% of patients were hospitalized during the 1‐year follow‐up.

Conclusions

In this unselected group of patients with long‐standing AF managed in primary care, hospitalizations and cardiovascular complications including strokes are frequent, illustrating the need to improve management of AF patients.
Hepatocellular Carcinoma Targeting Agents: Conjugates of Nitroimidazoles with Trimethyl Nordihydroguaiaretic Acid
Authors: Hsu Ming‐Hua , Wu Szu‐Chun , Pao Kuan‐Chuan , Unlu Irem , Gnabre John N. , Mold David E. , Huang Ru Chih C. , Hwu Jih Ru
Published: March 2014

Cancer has been a primary global health issue for decades, with hepatocellular carcinoma (HCC) resulting in more than half a million new cases annually. With survival rates as low as <5 % after five years, it remains a poorly treated cancer. Nordihydroguaiaretic acid (NDGA), an antioxidant, was previously proven effective against cancer cells. Nitroimidazole derivatives convert into reactive compounds under hypoxic conditions. In this study, eight methylated NDGAs containing a 2‐ or 4‐nitroimidazole moiety were synthesized as leads against HCC. Four of these conjugates, possessing a poly(ethylene glycol) tether, had superior aqueous solubility. These four NDGA–nitroimidazole conjugates were found to inhibit the proliferation HCC Hep3B cells with IC50 values between 10 and 15 μM. Furthermore, nitroimidazole‐conjugated NDGA derivatives exhibit better antiproliferative activity under hypoxic conditions.
Gold(I) Biscarbene Complexes Derived from Vascular‐Disrupting Combretastatin A‐4 Address Different Targets and Show Antimetastatic Potential
Authors: Muenzner Julienne K. , Biersack Bernhard , Kalie Hussein , Andronache Ion C. , Kaps Leonard , Schuppan Detlef , Sasse Florenz , Schobert Rainer
Published: March 2014

Gold N‐heterocyclic carbene (NHC) complexes are an emerging class of anticancer drugs. We present a series of gold(I) biscarbene complexes with NHC ligands derived from the plant metabolite combretastatin A‐4 (CA‐4) that retain its vascular‐disrupting effect, yet address different cellular and protein targets. Unlike CA‐4, these complexes did not interfere with tubulin, but with the actin cytoskeleton of endothelial and cancer cells. For the highly metastatic 518A2 melanoma cell line this effect was accompanied by a marked accumulation of cells in the G1 phase of the cell cycle and a suppression of active prometastatic matrix metalloproteinase‐2. Despite these mechanistic differences the complexes were as strongly antivascular as CA‐4 both in vitro in tube formation assays with human umbilical vein endothelial cells, and in vivo as to blood vessel disruption in the chorioallantoic membrane of chicken eggs. The antiproliferative effect of the new gold biscarbene complexes in a panel of six human cancer cell lines was impressive, with low sub‐micromolar IC50 values (72 h) even against CA‐4‐refractory HT‐29 colon and multidrug‐resistant MCF‐7 breast carcinoma cells. In preliminary studies with a mouse melanoma xenograft model the complexes led to significant decreases in tumor volume while being very well tolerated.
Synthesis and Electrocatalytic Properties of H2SO4‐Induced (100) Pt Nanoparticles Prepared in Water‐in‐Oil Microemulsion
Authors: Martínez‐Rodríguez Roberto A. , Vidal‐Iglesias Francisco J. , Solla‐Gullón José , Cabrera Carlos R. , Feliu Juan M.
Published: March 2014

The increasing number of applications for shape‐controlled metal nanoparticles (NPs) has led to the need for easy, cheap, and scalable methodologies. We report the synthesis of (100) preferentially oriented Pt NPs, with a particle size of 9 nm, by using a water‐in‐oil microemulsion method. The specific surface structure of the NPs is induced by the presence of H2SO4 in the water phase of the microemulsion. Interestingly, the results reported herein show how increasing amounts of H2SO4 lead to the formation of Pt NPs containing a larger amount of (100) sites on their surface. This preferential surface orientation is confirmed electrochemically by using the so‐called hydrogen adsorption/desorption process. In addition, transmission electron microscopy measurements confirm the presence of cubic‐like Pt NPs. Finally, the electrocatalytic properties of the Pt NPs are evaluated towards ammonia and CO electro‐oxidations, which are (100) structure‐sensitive reactions.
Unified subharmonic oscillation conditions for peak or average current mode control
Authors: Fang Chung‐Chieh
Published: March 2014

This paper is an extension of the author's recent research in which only buck converters were analyzed. Similar analysis can be equally applied to other types of converters. In this paper, a unified model is proposed for buck, boost, and buck–boost converters under peak or average current mode control to predict the occurrence of subharmonic oscillation. Based on the unified model, the associated stability conditions are derived in closed forms. The same stability condition can be applied to buck, boost, and buck–boost converters. Based on the closed‐form conditions, the effects of various converter parameters including the compensator poles and zeros on the stability can be clearly seen, and these parameters can be consolidated into a few ones. High‐order compensators such as type‐II and PI compensators are considered. Some new plots are also proposed for design purpose to avoid the instability. The instability is found to be associated with large crossover frequency. A conservative stability condition, agreed with the past research, is derived. The effect of the voltage loop ripple on the instability is also analyzed. Copyright © 2014 John Wiley & Sons, Ltd.
Clinician adherence to guidelines in the delivery of family‐based therapy for eating disorders
Authors: Kosmerly Stacey , Waller Glenn , Robinson Adele Lafrance
Published: March 2014

Objective

Clinicians have been shown to drift away from protocol in their delivery of evidence‐based treatments. This study explores this phenomenon in the delivery of family‐based therapy (FBT) for eating disorders, and the clinician characteristics that might explain such therapist drift.

Method

The participants were 117 clinicians who reported using FBT for eating disorders. They completed an online survey, which included questions relating to clinician characteristics, caseload, and reported use of FBT manuals and core therapeutic tasks, as well as a measure of anxiety.

Results

The use of core FBT tasks was higher than for other therapies, but there were still noteworthy gaps between recommended and reported practice. Approximately a third of clinicians reported delivering “FBT” that deviated very substantially from evidence‐based protocols, often appearing to be on an individual therapy basis. Using an FBT manual to guide treatment delivery was associated with greater adherence to recommended techniques. Clinician caseload and anxiety were associated with differences in the use of specific FBT tasks.

Discussion

Consistent with previous research regarding clinicians' use of other therapies, the delivery of FBT for the eating disorders is not homogeneous.

Conclusion

Further investigation of this phenomenon is needed to determine the impact of deviating from treatment protocols on the effectiveness of FBT for the eating disorders. © 2014 Wiley Periodicals, Inc. (Int J Eat Disord 2015; 48:223–229)
Insights into Different Donor Abilities in Bis(pyrazolyl)pyridinylmethane Transition Metal Complexes
Authors: Hoffmann Alexander , Flörke Ulrich , Herres‐Pawlis Sonja
Published: March 2014

We synthesised and characterised eleven complexes of the biomimetic bis(pyrazolyl)methanes (2‐pyridinyl)bis(pyrazolyl)methane [HC(Pz)2(Py)] and (2‐quinolinyl)bis(pyrazolyl)methane [HC(Pz)2(Qu)] with the transition metals cobalt, iron, copper and zinc. With the pyridinyl ligand HC(Pz)2(Py), we obtained the bifacial complexes [Co{HC(Pz)2(Py)}2]Cl2·2CH3CN (C1), [Co{HC(Pz)2(Py)}2][CF3SO3]2 (C2), [Fe{HC(Pz)2(Py)}2]Cl2·2CH3OH [C3], [Cu{HC(Pz)2(Py)}2]Cl2·2CH3OH (C4a) and [Cu{HC(Pz)2(Py)}2][CuCl3H2O] (C4b) and the monofacial complex [CuCl2{HC(Pz)2(Py)}]·CH3OH (C5); with the quinolinyl ligand HC(Pz)2(Qu), we obtained the bifacial complexes [Co{HC(Pz)2(Qu)}2][CoCl4]·4CH3CN·0.88CH2Cl2 (C6) and [Fe{HC(Pz)2(Qu)}2][FeCl4]·2CH3CN (C7), the monofacial complexes [FeCl2{HC(Pz)2(Qu)}] (C8) and [CuBr2{HC(Pz)2(Qu)}] (C9) and the bifacial zinc complex [Zn{HC(Pz)2(Qu)}2][ZnCl4] (C10). We explored the donor properties of the free ligands and the ligands in these complexes and found that the delicate donor competition is an intriguing field. By second‐order perturbation theory, pyrazolyl units are the stronger donors, although pyridinyl units are more basic. Isodesmic reactions indicate that the pyridinyl donors give a stronger complex stabilisation. This small bias can be disturbed by subtle variations of the coordination geometry, which is important in the bioinorganic context.
A Random Field LIBOR Market Model
Authors: Wu Tao L. , Xu Shengqiang
Published: March 2014

A random field LIBOR market model (RFLMM) is proposed by extending the LIBOR market model, with interest rate uncertainties modeled via a random field. First, closed‐form formulas for pricing caplet and swaption are derived. Then the random field LIBOR market model is integrated with the lognormal‐mixture model to capture the implied volatility skew/smile. Finally, the model is calibrated to cap volatility surface and swaption volatilities. Numerical results show that the random field LIBOR market model can potentially outperform the LIBOR market model in capturing caplet volatility smile and the pricing of swaptions, in addition to possessing other advantages documented in the previous literature (no need of frequent recalibration or to specify the number of factors in advance). © 2014 Wiley Periodicals, Inc. Jrl Fut Mark 34:580–606, 2014
Characterization of field margins in intensified agro-ecosystems—why narrow margins should matter in terrestrial pesticide risk assessment and management
Authors: Hahn Melanie , Lenhardt Patrick P , Brühl Carsten A
Published: March 2014

Field margins are important seminatural habitats in agro-ecosystems, but they can be negatively affected by pesticide inputs via direct overspray and spray drift. In Germany, risk mitigation measures (like buffer zones) to reduce pesticide inputs in terrestrial noncrop habitats do not have to be put in place by farmers next to narrow field margins (<3 m width). Because data on structure, size, and width of field margins are scarce, we identified field margins in 2 German agricultural landscapes (Rhineland-Palatinate [RLP], Brandenburg [BB]; 4000 ha each) using digital orthophotos and geographical information systems. In RLP, most of the field margins were less than 3 m wide (85% of margin length and 65% of the margin area), whereas in BB narrow field margins account for 45% of the margin length and 17% of the margin area. Hedgerows were only occasionally recorded. Hence, narrow grassy field margins can represent a large part of the available seminatural habitats adjoining agricultural sites and potentially act as corridors between further habitat patches. For this reason, these margins should be protected from pesticide inputs, at least in landscapes under intensive agricultural use. Field margins are also the main, so-called nontarget habitat protected by the terrestrial risk assessment for plants and arthropods. With many (narrow) margins not considered relevant for risk management, the current practice for protecting the biodiversity from negative effects of pesticides seems questionable. More data on field margin constitution in Germany and other European countries is necessary to critically assess the current practice of pesticide risk assessment and management on a larger scale. Integr Environ Assess Manag 2014;10:456–462. © 2014 SETAC

Key Points

Field margins, important habitats in agro-ecosystems that can be negatively affected by pesticides, were characterized by the use of digital orthophotos concerning their length, area, and width in two intensively used agricultural regions in Germany. Narrow field margins (less than 3m wide) represent common structures in both regions (85 and 50% of the margin length, 65 and 17% of the margin area, respectively), but in Germany, such narrow elements are not protected from pesticide inputs by risk mitigation measures like buffer zones. As narrow margins can provide habitats for e.g. arthropod predators as well as herbivores, and are assumed to act as corridors for species movements, they should be protected from pesticide inputs at least in intensively used agricultural landscapes to benefit biodiversity.
Stereoselective DielsAlder Reactions Promoted under Continuous‐Flow Conditions by Silica‐Supported Chiral Organocatalysts
Authors: Porta Riccardo , Benaglia Maurizio , Chiroli Valerio , Coccia Francesca , Puglisi Alessandra
Published: March 2014

Silica nanoparticles of different morphological properties were functionalized with enantiomerically pure imidazolidinones, through different immobilization techniques; stainless‐steel columns were then loaded with silica bearing chiral organocatalysts to realize chiral “homemade” reactors. The influence of the material properties and immobilization procedures on the chemical and stereochemical activities of the chiral HPLC columns was studied by performing organocatalyzed DielsAlder reactions between cyclopentadiene and α,β‐unsaturated aldehydes under continuous‐flow conditions. In some cases, excellent enantioselectivities were obtained, thus showing that a catalytic reactor may work efficiently to continuously produce enantiomerically enriched cycloadducts for more than 200 h. Regeneration of the organocatalytic column was also partially accomplished, although associated with a slightly lower enantioselectivity, thus prolonging the “life” of the reactor to more than 300 h.
Retinoic acid reduces solvent‐induced neuropathy and promotes neural regeneration in mice
Authors: Palencia Guadalupe , Hernández‐Pedro Norma , Saavedra‐Perez David , Peña‐Curiel Omar , Ortiz‐Plata Alma , Ordoñez Graciela , Flores‐Estrada Diana , Sotelo Julio , Arrieta Oscar
Published: March 2014

In humans, exposure to organic solvents (OS) is frequent in work activities or as a recreational inhalant, inducing severe neuropathy (secondary to demyelization of peripheral nerves). We have previously shown that all‐trans retinoic acid (ATRA) increases local content of neural growth factor (NGF), improving peripheral neuropathy of diverse origins. In this study, we evaluated the effect of ATRA on OS‐induced peripheral neuropathy in experimental mice. Two simultaneous experiments were performed. The first one aimed to evaluate ATRA for the prevention of damage induced by OS, the second to test ATRA as an OS‐induced neuropathy treatment. Nociceptive threshold latency and NGF concentration in serum and in peripheral nerves were determined. Morphological changes and evidence of sciatic nerve regeneration were evaluated. Mice exposed to OS developed neuropathy and axonal degeneration. ATRA diminished the effects of OS inhalation on sensorial changes and nerve morphology. Treatment with ATRA reversed sensorial and nerve morphological changes of OS‐induced neuropathy, and this was associated with increased contents of NGF. Similar to previous experiences on diabetic and toxic neuropathy, ATRA reduced and partially reversed the peripheral neuropathy caused by OS exposure. These favorable effects apparently are due to local production of NGF induced by neural regeneration in response to the administration of retinoic acid. © 2014 Wiley Periodicals, Inc.
Effects of application of corn straw on soil microbial community structure during the maize growing season
Authors: Lu Ping , Lin Yin‐Hua , Yang Zhong‐Qi , Xu Yan‐Peng , Tan Fei , Jia Xu‐Dong , Wang Miao , Xu De‐Rong , Wang Xi‐Zhuo
Published: March 2014

This study investigated the influence of corn straw application on soil microbial communities and the relationship between such communities and soil properties in black soil. The crop used in this study was maize (Zea mays L.). The five treatments consisted of applying a gradient (50, 100, 150, and 200%) of shattered corn straw residue to the soil. Soil samples were taken from May through September during the 2012 maize growing season. The microbial community structure was determined using phospholipid fatty acid (PLFA) analysis. Our results revealed that the application of corn straw influenced the soil properties and increased the soil organic carbon and total nitrogen. Applying corn straw to fields also influenced the variation in soil microbial biomass and community composition, which is consistent with the variations found in soil total nitrogen (TN) and soil respiration (SR). However, the soil carbon‐to‐nitrogen ratio had no effect on soil microbial communities. The abundance of PLFAs, TN, and SR was higher in C1.5 than those in other treatments, suggesting that the soil properties and soil microbial community composition were affected positively by the application of corn straw to black soil. A Principal Component Analysis indicated that soil microbial communities were different in the straw decomposition processes. Moreover, the soil microbial communities from C1.5 were significantly different from those of CK (p < 0.05). We also found a high ratio of fungal‐to‐bacterial PLFAs in black soil and significant variations in the ratio of monounsaturated‐to‐branched fatty acids with different straw treatments that correlated with SR (p < 0.05). These results indicated that the application of corn straw positively influences soil properties and soil microbial communities and that these properties affect these communities. The individual PLFA signatures were sensitive indicators that reflected the changes in the soil environment condition.
Raman identification of lonsdaleite in Popigai impactites
Authors: Goryainov S. V. , Likhacheva A. Y. , Rashchenko S. V. , Shubin A. S. , Afanas'ev V. P. , Pokhilenko N. P.
Published: March 2014

Micro‐Raman spectroscopy and X‐ray diffraction method (XRD) were used to characterize impact carbonaceous rocks excavated from the Popigai crater (Siberia). The deconvolution of the first‐order Raman spectra of the rocks containing different amounts of carbon phases (diamond, lonsdaleite and graphite) allowed the identification of lonsdaleite spectrum. The most intensive band at 1292–1303 cm−1 was ascribed to A1g vibration mode of lonsdaleite, whereas the less intense band at 1219–1244 cm−1 was attributed, in agreement with previously reported ab initio calculations, to E2g vibration mode. The established correlation between the intensities of Raman and XRD peaks permits a rough estimation of lonsdaleite/diamond phase ratio in the impact rocks using micro‐Raman measurements. The second‐order Raman spectra of lonsdaleite–diamond rocks were recorded. Copyright © 2014 John Wiley & Sons, Ltd.
Preparation of SERS active Ag nanoparticles encapsulated by phospholipids
Authors: An Hyeun Hwan , Han Won Bae , Kim Yongdeok , Kim Hee‐Soo , Oh Yoong , Yoon Chong Seung
Published: March 2014

A cost‐effective way of fabricating lipid‐coated surface‐enhanced Raman spectroscopy (SERS) substrate having reproducible high SERS activity was proposed. Ag nanoparticle embedded in 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) and 1,2‐dioleoyl‐3‐trimethylammonium‐propane (DOTAP) membranes was produced by direct deposition of a 5‐nm‐thick layer of Ag onto the solid‐supported phospholipid membrane, and subsequent dissolution of the Ag nanoparticle‐embedded membrane in iso‐octane allowed easy one‐pot fabrication of DOPC‐ or DOTAP‐coated Ag nanoparticles. In particular, DOTAP produced nearly monodisperse lipid‐encapsulated Ag nanoparticles (9 nm in diameter) exhibiting reproducible high SERS activity (detecting up to 10 nM of rhodamine 6G and 0.5 μM of glutathione). In addition, the process was modified to incorporate variety of Raman active molecules (rhodamine 6G, malachite green, 4‐aminothiopheonol, 4‐mercaptopyridine) into the particle‐encapsulating lipid bilayer. The DOTAP/Raman dye‐coated Ag nanoparticles also generated high SERS activity to enable potential application of the DOTAP/Raman dye‐coated Ag nanoparticles feasible in different areas. Copyright © 2014 John Wiley & Sons, Ltd.