bluuebunny/crossref_metadata_2025 huggingface dataset:
Tras el Concepto de la Evaluación Educativa
Authors: Castro Leví , Benito Martínez José
Published: May 2014

Es parte de la naturaleza racional del hombre emitir juicios acerca de su entorno. Desde sus orígenes a la fecha el concepto de evaluación ha evolucionado, modificado y ampliado con aportaciones de teóricos e investigadores de la psicología y la educación. Muchos de estos aportes se han realizado con la esperanza aproximarnos a un concepto más útil en el marco de las nuevas tendencias pedagógicas. El término evaluación tiene su origen en el campo de la industria y hace apenas un siglo se implantó en el ámbito de la educación; no obstante, ha sufrido profundas transformaciones, desde ser considerada como sinónimo de medir, hasta concebirse como un proceso sistemático. Desde el punto de vista etimológico, evaluación procede del antiguo francés velue: acción y efecto de evaluar, lo cual alude a valorar cuan bueno o malo es un “objeto”; así evaluación es el acto de señalar el valor de una cosa. Ha quedado establecido aquí que el concepto de evaluación es educativa es complejo y se ha construido a través de la historia con aportaciones de diversas corrientes filosóficas, psicológicas y pedagógicas. En la actualidad existe un acuerdo en cuento a la evaluación educativa como un proceso riguroso que permite la indagación del fenómeno evaluado a fin de emitir juicios basados en un marco de referencia teórico que permita tomar decisiones válidas. DOI: http://dx.doi.org/10.5377/paradigma.v20i33.1427 Paradigma: Revista de Investigación Educativa. Año 20. No. 33; 103-115
“Aproximaciones a la historia de la lectura en Honduras: Lecturas en soledad y lecturas en público en el período liberal de finales del siglo XIX y principios del XX”
Authors: Amaya Banegas Jorge Alberto
Published: May 2014

DOI: http://dx.doi.org/10.5377/paradigma.v20i33.1428 Paradigma: Revista de Investigación Educativa. Año 20. No. 33; 117-150
Methylene Blue Dye-Induced Skin Necrosis in Immediate Breast Reconstruction: Evaluation and Management
Authors: Lee Ji Hwan , Chang Choong Hyun , Park Chan Heun , Kim June-Kyu
Published: May 2014

Background For early breast cancer patients, skin-sparing mastectomy or nipple-sparing mastectomy with sentinel lymph node biopsy has become the mainstream treatment for immediate breast reconstruction in possible cases. However, a few cases of skin necrosis caused by methylene blue dye (MBD) used for sentinel lymph node localization have been reported.

Methods Immediate breast reconstruction using a silicone implant was performed on 35 breasts of 34 patients after mastectomy. For sentinel lymph node localization, 1% MBD (3 mL) was injected into the subareolar area. The operation site was inspected in the postoperative evaluation.

Results Six cases of immediate breast reconstruction using implants were complicated by methylene blue dye. One case of local infection was improved by conservative treatment. In two cases, partial necrosis and wound dehiscence of the incision areas were observed; thus, debridement and closure were performed. Of the three cases of wide skin necrosis, two cases underwent removal of the dead tissue and implants, followed by primary closure. In the other case, the breast implant was salvaged using latissimus dorsi musculocutaneous flap reconstruction.

Conclusions The complications were caused by MBD toxicity, which aggravated blood disturbance and skin tension after implant insertion. When planning immediate breast reconstruction using silicone implants, complications of MBD should be discussed in detail prior to surgery, and appropriate management in the event of complications is required.
Predicting the Permanent Safe Donor Area for Hair Transplantation in Koreans with Male Pattern Baldness according to the Position of the Parietal Whorl
Authors: Park Jae Hyun , Na Young Cheon , Moh Jae Seong , Lee Seung Yong , You Seung Hyun
Published: May 2014

Background The most crucial factor in hair transplantation for male pattern baldness (MPB) patients is the efficient utilization of the donor-recipient ratio. However, there is no known factor that scientifically predicts the rate of progression of alopecia or indicates a permanently safe donor area.

Methods The study considered 1,008 Korean adult males with MPB; of these, it excluded 56 males with an absence of parietal whorls (PWs). The authors investigated the distance from the vertical bimeatal line (VM) to the PW, from the PW to the upper border of the helical rim (HR), and the distance from the PW to the occipital fringe (OF) in 952 subjects with a PW. Furthermore, we examined the distance from the PW to the OF considering the duration of alopecia and age in 322 subjects with vertex alopecia.

Results The distance between the VM and PW varied from 1.5 to 11 cm, with an average distance of 6.25 cm. The PW-HR distance ranged from 3.4 to 17.5 cm, and the average distance was 7.79 cm. The PW-OF distance ranged from 0.5 to 5.5 cm, and the average distance was 2.37 cm.

Conclusions For the PW, very large variations existed in the vertical direction. The position of the PW could predict the progression range of the total alopecia of the vertex. Alopecia mostly progresses within 6 cm of the PW toward the occipital side.
La littérature de jeunesse : le lecteur, l’oeuvre, les passeurs et le passage
Authors: Noël-Gaudreault Monique , Le Brun Claire
Published: May 2014

Cet article est une introduction à un dossier sur la littérature jeunesse (albums et romans) comme objet de médiation culturelle entre l’enseignant et le jeune lecteur. En français langue d’enseignement, du point de vue des corpus, la nature et les fonctions de thèmes existentiels sont examinées (Hétier et Chirouter), ainsi que les interactions langagières qu’ils génèrent lors de débats interprétatifs (Champagne-Vergez). Du point de vue des stratégies didactiques, le cercle de lecture fait l’objet d’une recherche qui porte sur la progression, chez les élèves, de la compétence à lire un même roman, du primaire au secondaire (Hébert). Enfin, pour le préscolaire, trois articles : 1) sur le contrat lecture en maternelle, destiné à favoriser l’entrée précoce de l’enfant dans l’écrit (Le Guirinec) ; 2) sur la comparaison de pratiques d’enseignantes expertes formées à la lecture à voix haute pour travailler les inférences au préscolaire (Dupin de Saint-André et al.) ; 3) sur les interactions possibles entre littérature et mathématiques par le biais des livres à compter (Camenisch).
Lire, commenter, discuter un même roman au primaire et au secondaire : quelles différences ?
Authors: Hébert Manon
Published: May 2014

Plusieurs recherches ont souligné l’intérêt d’activités centrées sur l’expression du sujet lecteur, comme les journaux et les cercles de lecture entre pairs, pour le développement de la compétence littéraire à l’école. Cependant, nous avons encore très peu de données développementales pour comprendre comment peut progresser cette compétence selon l’âge. Dans une recherche empirique conduite dans trois classes (6eprimaire, 2eet 4esecondaire), où les élèves ont expérimenté ces activités pour lire un même roman,Le passeur(Lowry, 1992), nos analyses qualitative et quantitative révèlent quelques différences dans les modes de lecture et types de sujets abordés à l’écrit, ainsi que dans les modes de collaboration à l’oral.
Un contrat-lecture en maternelle au service d’une littératie émergente : quelles médiations de l’album pour quelles lectures partagées ?
Authors: Le Guirinec Pierre
Published: May 2014

Un dispositif pédagogique initié en maternelle, le contrat-lecture, vise à impliquer l’école dans une littératie émergente, en favorisant la participation des familles et le partage des récits en classe. L’objet du présent article est de mettre à l’épreuve, à travers ce dispositif, les concepts de médiation littéraire et de lecture partagée. La qualité de l’engagement des familles et des restitutions enfantines, ainsi que la diversification des passeurs de récits, constituent des indicateurs déterminants pour une expertise théorique du contrat-lecture dans la perspective d’un examen anthropologique de la littératie.
Perceptions de l’éducation en français au Nouveau-Brunswick d’après les écrits de l’Ordre de Jacques Cartier dans L’Émerillon
Authors: Bérubé Julie
Published: May 2014

Ce texte illustre la position de l’Ordre de Jacques Cartier en Acadie du Nouveau-Brunswick, entre 1933 et 1965, dans le domaine de l’éducation, par l’analyse de textes publiés dans son organe, L’Émerillon. Il propose d’abord une synthèse de l’implantation et du fonctionnement de l’Ordre, suivie d’un bref historique de l’accès à l’éducation pour les francophones de cette province, pour enfin examiner le discours tenu par cette organisation en ce qui a trait à l’éducation de même que la perception de la langue qui s’en dégage.
Les atouts et avantages du bilinguisme à Moncton : entre discours et réalité
Authors: LeBlanc Matthieu
Published: May 2014

Dans cet article, nous nous pencherons sur la question de savoir si, dans les faits, le bilinguisme des francophones de Moncton constitue un réel avantage sur le marché du travail et, si oui, dans quelle mesure. Pour ce faire, nous nous appuierons sur les résultats de deux études ethnographiques réalisées en milieu de travail. Nous tenterons de montrer que, malgré le discours qui circule sur les avantages du bilinguisme, la question du bilinguisme en milieu de travail est fort complexe et que, somme toute, les avantages, du moins pour les francophones, se limitent essentiellement à l’accès aux postes.
Des voix qui se répondent
Authors: Boudreau Annette
Published: May 2014

L’objectif de l’article est d’examiner comment lesreprésentationslinguistiques des francophones, alimentées par lesidéologieslinguistiques dominantes de différentes époques, se sont construites dans le sud-est du Nouveau-Brunswick de la fin du XIXe siècle à nos jours en mettant l’accent sur deux périodes principales, de 1960 à 1970, où l’on analyse des journaux étudiants de l’époque, et de 2000 à aujourd’hui, où l’on examine des sites internet. La ville de Moncton est privilégiée dans l’analyse étant donné le nombre d’institutions acadiennes qui y sont installées, l’hétérogénéité culturelle et linguistique qui la caractérise, et les discours abondants sur la langue qui y circulent.
Le trajet linguistique des emprunts dans le chiac de Moncton : quelques observations
Authors: Perrot Marie-Ève
Published: May 2014

À partir d’exemples précis, l’article montre que le trajet linguistique des emprunts dans le chiac de Moncton se caractérise par un double mouvement d’anglicisation et de refrancisation. Prenant en compte différents aspects de la situation sociolinguistique actuelle, il propose quelques éléments d’explication des tendances repérées. Il illustre en quoi la comparaison avec d’autres corpus de français acadien en contact avec l’anglais apporte un éclairage intéressant sur l’évolution des emprunts, et soulève la question d’une éventuelle spécificité du chiac par rapport à ces variétés.
Pharmacological inhibition of cystine–glutamate exchange induces endoplasmic reticulum stress and ferroptosis
Authors: Dixon Scott J , Patel Darpan N , Welsch Matthew , Skouta Rachid , Lee Eric D , Hayano Miki , Thomas Ajit G , Gleason Caroline E , Tatonetti Nicholas P , Slusher Barbara S , Stockwell Brent R
Published: May 2014

Exchange of extracellular cystine for intracellular glutamate by the antiporter system xc−is implicated in numerous pathologies. Pharmacological agents that inhibit system xc−activity with high potency have long been sought, but have remained elusive. In this study, we report that the small molecule erastin is a potent, selective inhibitor of system xc−. RNA sequencing revealed that inhibition of cystine–glutamate exchange leads to activation of an ER stress response and upregulation ofCHAC1, providing a pharmacodynamic marker for system xc−inhibition. We also found that the clinically approved anti-cancer drug sorafenib, but not other kinase inhibitors, inhibits system xc−function and can trigger ER stress and ferroptosis. In an analysis of hospital records and adverse event reports, we found that patients treated with sorafenib exhibited unique metabolic and phenotypic alterations compared to patients treated with other kinase-inhibiting drugs. Finally, using a genetic approach, we identified new genes dramatically upregulated in cells resistant to ferroptosis.
Nonlinear damping of chorus emissions at local half cyclotron frequencies observed by Geotail at L > 9
Authors: Habagishi Toshihiro , Yagitani Satoshi , Omura Yoshiharu
Published: May 2014

We have performed a statistical analysis of upper band and lower band chorus emissions observed by the Geotail spacecraft. Chorus elements are generated near the magnetic equator (or the high‐latitude minimum‐B pockets in the outer magnetosphere) as discrete emissions covering a frequency range of 0.1–0.65 fce0, where fce0 is the cyclotron frequency in the generation region, with wave vectors parallel to the ambient magnetic field. As the emissions propagate away from the generation region, it is possible that they undergo the nonlinear damping at half the local cyclotron frequency 0.5 fce because of the quasi‐parallel propagation. The nonlinear damping can separate the emissions into the upper band and lower band chorus emissions. We have found that the lower cutoff of the upper band emissions coincides with 0.5 fce, while the upper cutoff of the lower band emissions represents 0.5 fce0. When 0.5 fce exceeds 0.65 fce0, the chorus emission is observed as a lower band‐only emission.
Anisotropic Rayleigh wave phase velocity maps of eastern China
Authors: Legendre C. P. , Deschamps F. , Zhao L. , Lebedev S. , Chen Q.‐F.
Published: May 2014

We explore the variations of Rayleigh wave phase velocity beneath eastern China in a broad period range (20–200 s). Rayleigh wave dispersion curves are measured by the two‐station technique for a total of 734 interstation paths using vertical component broadband waveforms at 39 seismic stations in eastern China from 466 global earthquakes. In addition, 599 waveform inversion interstation measurements were added to this data set. The interstation dispersion curves are then inverted for high‐resolution isotropic and azimuthally anisotropic phase velocity maps at periods between 20 and 200 s. At shorter periods sampling the crustal depth range, phase velocities are higher in the southeastern part of the region, reflecting the thinner crust there. The Jiangnan Belt separates Cathaysia from the Yangtze Craton, the latter with thicker crust and a deep, high‐velocity cratonic root. The eastern part of Yangtze Craton, however, east of 115–116°E, does not display a deep root and has a thin lithosphere. Azimuthal anisotropy at long periods (>120 s) shows fast propagation directions broadly similar to that of the absolute plate motion. Beneath Cathaysia and eastern Yangtze Craton, anisotropy in the asthenosphere is strong and suggests coast‐perpendicular flow. Asthenospheric flow from beneath China's thick continental lithosphere toward the thinner lithosphere of the margin and the resulting decompression melting may be the fundamental causes of the intraplate basaltic volcanism along the eastern coast of China.
Evaluating the impact of urban morphology configurations on the accuracy of urban canopy model temperature simulations with MODIS
Authors: Monaghan Andrew J. , Hu Leiqiu , Brunsell Nathaniel A. , Barlage Michael , Wilhelmi Olga V.
Published: May 2014

Simulations of the urban environment contribute to assessments of current and future urban vulnerabilities to extreme heat events. The accuracy of simulations of the urban canopy can be degraded by inaccurate or oversimplified representations of the urban‐built environment within models. Using a 10 year (2003–2012) series of offline 1 km simulations over Greater Houston with the High‐Resolution Land Data Assimilation System (HRLDAS), this study explores the model accuracy gained by progressively increasing the complexity of the urban morphology representation in an urban canopy model. The fidelity of the simulations is primarily assessed by a spatiotemporally consistent comparison of a newly developed HRLDAS radiative temperature variable with remotely sensed estimates of land surface temperature from the Moderate Resolution Imaging Spectroradiometer. The most accurate urban simulations of radiative temperature are yielded from experiments that (1) explicitly specify the urban fraction in each pixel and (2) include irrigation. The former modification yields a gain in accuracy that is larger than for other changes, such as increasing the number of urban land use types. The latter modification (irrigation) substantially reduces simulated temperature biases and increases model precision compared to model configurations that lack irrigation, presumably because watering of lawns, parks, etc. is a common activity that should be represented in urban canopy models (although it is generally not). Ongoing and future efforts to improve urban canopy model simulations may achieve important gains through better representations of urban morphology, as well as processes that affect near‐surface energy partitioning within cities, such as irrigation.
A review of radio channel models for body centric communications
Authors: Cotton Simon L. , D'Errico Raffaele , Oestges Claude
Published: May 2014

The human body is an extremely challenging environment for the operation of wireless communications systems, not least because of the complex antenna‐body electromagnetic interaction effects which can occur. This is further compounded by the impact of movement and the propagation characteristics of the local environment which all have an effect upon body centric communications channels. As the successful design of body area networks (BANs) and other types of body centric system is inextricably linked to a thorough understanding of these factors, the aim of this paper is to conduct a survey of the current state of the art in relation to propagation and channel models primarily for BANs but also considering other types of body centric communications. We initially discuss some of the standardization efforts performed by the Institute of Electrical and Electronics Engineers 802.15.6 task group before focusing on the two most popular types of technologies currently being considered for BANs, namely narrowband and Ultrawideband (UWB) communications. For narrowband communications the applicability of a generic path loss model is contended, before presenting some of the scenario specific models which have proven successful. The impacts of human body shadowing and small‐scale fading are also presented alongside some of the most recent research into the Doppler and time dependencies of BANs. For UWB BAN communications, we again consider the path loss as well as empirical tap delay line models developed from a number of extensive channel measurement campaigns conducted by research institutions around the world. Ongoing efforts within collaborative projects such as Committee on Science and Technology Action IC1004 are also described. Finally, recent years have also seen significant developments in other areas of body centric communications such as off‐body and body‐to‐body communications. We highlight some of the newest relevant research in these areas as well as discussing some of the advanced topics which are currently being addressed in the field of body centric communications.
Synthesis of a C2‐Symmetrical Tetrakis(arylethynyl) Cavitand and Formation of Hybrid Hydrogen‐Bonded/Metal‐Ligand Coordination Supramolecular Capsules
Authors: Nito Yuki , Nakada Keiko , Kobayashi Kenji , Yamanaka Masamichi
Published: May 2014

A C2‐symmetrical tetrakis(arylethynyl) cavitand was synthesized. Spontaneous formation of hybrid hydrogen bonded/metal‐ligand coordination supramolecular capsules occurs upon mixing 1 with cis‐coordinated Pt2+ or Pd2+ metal complexes. The hybrid supramolecular capsules encapsulated neutral guest molecules only in polar solvents.
Aminomethylenehelicene Oligomers Possessing Flexible Two‐Atom Linker Form a Stimuli‐Responsive Double‐Helix in Solution
Authors: Shigeno Masanori , Sato Masahiko , Kushida Yo , Yamaguchi Masahiko
Published: May 2014

Aminomethylenehelicene oligomers up to the (M)‐heptamer were synthesized by reductive amination from a formylhelicene building block. The oligomers containing more than three helicenes formed a double helix in 1,3‐dilfuorobenzene. The (M)‐tetramer and (M)‐pentamer unfolded into a random coil by heating to 60 °C, whereas the (M)‐hexamer only slightly unfolded at the same temperature. A two‐sided thermal hysteresis was detected in the structural change of the (M)‐tetramer and (M)‐pentamer during cooling and heating. The (M)‐pentamer and (M)‐hexamer unfolded with the addition of trifluoroacetic acid and regenerated a double helix with the addition of triethylamine.
Anatomic relationship of nasolacrimal duct and major lateral wall landmarks: cadaveric study with surgical implications
Authors: Ali Mohammad Javed , Nayak Jayakar V. , Vaezeafshar Reza , Li Gang , Psaltis Alkis James
Published: May 2014

Background

Detailed knowledge of the surgical anatomic landmarks of the lateral nasal wall is important for safe and successful endoscopic sinonasal surgery. We sought to determine the relationship of major landmarks to the nasolacrimal duct (NLD).

Methods

Twenty mid‐sagittal head sections of 10 fresh frozen cadavers were studied after removal of the nasal septum. The insertion of the alar cartilage into the maxilla was taken as a fixed point and all measurements were performed in a defined axial plane at the level of the maxillary sinus natural ostium. Two surgeons independently recorded each measurement 3 times with an average of the readings used for statistical analysis.

Results

The overall agreement index was excellent (r = 0.84) between the observers. At the level of maxillary ostium, the mean distance from the alar rim to the NLD was 43.05 ± 4.76 mm on the right and 41.25 ± 4.56 mm on the left. The most anterior projection of the middle turbinate head was noted to be anterior to the NLD in 70% of specimens. In positional relationship, the maxillary line was posterior to the NLD in 55%, whereas the bulla ethmoidalis and the free edge of uncinate process were uniformly posterior to the NLD in all the specimens.

Conclusion

This study provides useful anatomic and positional relationships between the NLD and major lateral wall landmarks. Although the maxillary line and the head of the middle turbinate are often considered useful guides to the position of the ipsilateral NLD, their spatial relationship to the NLD is not consistent. These landmarks, therefore, cannot be solely relied upon during surgery to avoid injury to the NLD.
Molecular pathogenesis of polymerase gamma–related neurodegeneration
Authors: Tzoulis Charalampos , Tran Gia Tuong , Coxhead Jonathan , Bertelsen Bjørn , Lilleng Peer K. , Balafkan Novin , Payne Brendan , Miletic Hrvoje , Chinnery Patrick F. , Bindoff Laurence A.
Published: May 2014

Objective

Polymerase gamma (POLG) mutations are a common cause of mitochondrial disease and have also been linked to neurodegeneration and aging. We studied the molecular mechanisms underlying POLG‐related neurodegeneration using postmortem tissue from a large number of patients.

Methods

Clinical information was available from all subjects. Formalin‐fixed and frozen brain tissue from 15 patients and 23 controls was studied employing a combination of histopathology, immunohistochemistry, and molecular studies of microdissected neurons.

Results

The primary consequence of POLG mutation in neurons is mitochondrial DNA depletion. This was already present in infants with little evidence of neuronal loss or mitochondrial dysfunction. With longer disease duration, we found an additional, progressive accumulation of mitochondrial DNA deletions and point mutations accompanied by increasing numbers of complex I–deficient neurons. Progressive neurodegeneration primarily affected the cerebellar systems and dopaminergic cells of the substantia nigra. Superimposed on this chronic process were acute, focal cortical lesions that correlated with epileptogenic foci and that showed massive neuronal loss.

Interpretation

POLG mutations appear to compromise neuronal respiration via a combination of early and stable depletion and a progressive somatic mutagenesis of the mitochondrial genome. This leads to 2 distinct but overlapping biological processes: a chronic neurodegeneration reflected clinically by progressive ataxia and cognitive impairment, and an acute focal neuronal necrosis that appears to be related to the presence of epileptic seizures. Our findings offer an explanation of the acute‐on‐chronic clinical course of this common mitochondrial encephalopathy. ANN NEUROL 2014;76:66–81
Proton Conductivities of Graphene Oxide Nanosheets: Single, Multilayer, and Modified Nanosheets
Authors: Hatakeyama Kazuto , Karim Mohammad Razaul , Ogata Chikako , Tateishi Hikaru , Funatsu Asami , Taniguchi Takaaki , Koinuma Michio , Hayami Shinya , Matsumoto Yasumichi
Published: May 2014

Proton conductivities of layered solid electrolytes can be improved by minimizing strain along the conduction path. It is shown that the conductivities (σ) of multilayer graphene oxide (GO) films (assembled by the drop‐cast method) are larger than those of single‐layer GO (prepared by either the drop‐cast or the Langmuir‐Blodgett (LB) method). At 60 % relative humidity (RH), the σ value increases from 1×10−6 S cm−1 in single‐layer GO to 1×10−4 and 4×10−4 S cm−1 for 60 and 200 nm thick multilayer films, respectively. A sudden decrease in conductivity was observed for with ethylenediamine (EDA) modified GO (enGO), which is due to the blocking of epoxy groups. This experiment confirmed that the epoxide groups are the major contributor to the efficient proton transport. Because of a gradual improvement of the conduction path and an increase in the water content, σ values increase with the thickness of the multilayer films. The reported methods might be applicable to the optimization of the proton conductivity in other layered solid electrolytes.
Multifunktionale, Defekt‐manipulierte Metall‐organische Gerüste mit Rutheniumzentren: Sorption und katalytische Eigenschaften
Authors: Kozachuk Olesia , Luz Ignacio , Llabrés i Xamena Francesc X. , Noei Heshmat , Kauer Max , Albada H. Bauke , Bloch Eric D. , Marler Bernd , Wang Yuemin , Muhler Martin , Fischer Roland A.
Published: May 2014

Das Konzept der “festen Lösungen mit gemischten Linkern” (mixed‐linker solid solution concept) ist angewendet worden, um die Metallzentren des gemischtvalenten RuII/III‐Analogons der bekannten Familie der [M3II,II(btc)2]‐MOFs (M=Cu, Mo, Cr, Ni oder Zn; btc=Benzol‐1,3,5‐tricarboxylat) zu modellieren und strukturelle Defekte in das Gerüst mit teilweise fehlenden Carboxylatliganden an den Ru2‐“Schaufelradeinheiten” einzubringen. Pyridin‐3,5‐dicarboxylat (pydc) als zweiter, Defekt‐bildender Linker von ähnlicher Größe wie btc, aber geringerer Ladung führt zu einem porösen Derivat von Ru‐MOF mit Eigenschaften, die sich von denen des Defekt‐freien MOF unterscheiden. So bewirkt das Einbringen von pydc außer der Bildung von zusätzlichen koordinativ ungesättigten Metallzentren auch eine partielle Reduktion des Rutheniums. Die modifizierten Ru‐Zentren sind für die Aktivität der “defekten” Varianten hinsichtlich dissoziativer Chemisorption von CO2, erhöhter CO‐Sorption, Bildung von Ru‐H‐Spezies und katalytischer Hydrierung von Olefinen verantwortlich.
Egg White Varnishes on Ancient Paintings: A Molecular Connection to Amyloid Proteins
Authors: Imbrogno Joseph , Nayak Arpan , Belfort Georges
Published: May 2014

For about 400 years, egg white was used to coat and protect paintings without detailed understanding of its molecular properties. A molecular basis is provided for its advantageous properties and one of its protective properties is demonstrated with oxygen transport behavior. Compared to the native secondary structure of ovalbumin in solution of circa 33 % α‐helix and β‐sheet, attenuated total reflection–FTIR (ATR‐FTIR) spectra showed a 73 % decrease of α‐helix content and a 44 % increase of β‐sheet content over eight days. The data suggest that the final coating of dissolved ovalbumin from egg white after long exposure to air, which is hydrophobic, comprises mostly β‐sheet content (ca. 50 %), which is predicted to be the lowest‐energy structure of proteins and close to that found in amyloid fibrils. Coating a synthetic polytetrafluoroethylene membrane with multiple layers of egg white decreased oxygen diffusion by 50 % per layer with a total decrease of almost 100 % for four layers.
Properties of Sizeable [n]Cycloparaphenylenes as Molecular Models of Single‐Wall Carbon Nanotubes Elucidated by Raman Spectroscopy: Structural and Electron‐Transfer Responses under Mechanical Stress
Authors: Alvarez Miriam Peña , Burrezo Paula Mayorga , Kertesz Miklos , Iwamoto Takahiro , Yamago Shigeru , Xia Jianlong , Jasti Ramesh , Navarrete Juan T. López , Taravillo Mercedes , Baonza Valentín G. , Casado Juan
Published: May 2014

[n]Cycloparaphenylenes behave as molecular templates of “perfectly chemically defined” single‐wall carbon nanotubes. These [n]CPP molecules have electronic, mechanical, and chemical properties in size correspondence with their giant congeners. Under mechanical stress, they form charge‐transfer salts, or complexes with fullerene, by one‐electron concave–convex electron transfer.
Pharmacophore Reassignment for Induction of the Immunosurveillance Cytokine TRAIL
Authors: Jacob Nicholas T. , Lockner Jonathan W. , Kravchenko Vladimir V. , Janda Kim D.
Published: May 2014

Tumor necrosis factor (TNF)‐related apoptosis‐inducing ligand (TRAIL) is an immunosurveillance cytokine that kills cancer cells but demonstrates little toxicity against normal cells. While investigating the TRAIL‐inducing imidazolinopyrimidinone TIC10, a misassignment of its active structure was uncovered. Syntheses of the two isomers, corresponding to the published and reassigned structures, are reported. The ability of each to induce TRAIL expression in macrophages was investigated and it was found that only the compound corresponding to the reassigned structure shows the originally reported activity; the compound corresponding to the published structure is inactive. Importantly, this structural reassignment has furnished a previously unknown antitumor pharmacophore.
Anion‐Coordination‐Induced Turn‐On Fluorescence of an Oligourea‐Functionalized Tetraphenylethene in a Wide Concentration Range
Authors: Zhao Jie , Yang Dong , Zhao Yanxia , Yang Xiao‐Juan , Wang Yao‐Yu , Wu Biao
Published: May 2014

A tetrakis(bisurea)‐decorated tetraphenylethene (TPE) ligand (L2) was designed, which, upon coordination with phosphate ions, displays fluorescence “turn‐on” over a wide concentration range, from dilute to concentrated solutions and to the solid state. The fluorescence enhancement can be attributed to the restriction of the intramolecular rotation of TPE by anion coordination. The crystal structure of the A4L2 (A=anion) complex of L2 with monohydrogen phosphate provides direct evidence for the coordination mode of the anion. This “anion‐coordination‐induced emission” (ACIE) is another approach for fluorescence turn‐on in addition to aggregation‐induced emission (AIE).
Triazine‐Based Graphitic Carbon Nitride: a Two‐Dimensional Semiconductor
Authors: Algara‐Siller Gerardo , Severin Nikolai , Chong Samantha Y. , Björkman Torbjörn , Palgrave Robert G. , Laybourn Andrea , Antonietti Markus , Khimyak Yaroslav Z. , Krasheninnikov Arkady V. , Rabe Jürgen P. , Kaiser Ute , Cooper Andrew I. , Thomas Arne , Bojdys Michael J.
Published: May 2014

Graphitic carbon nitride has been predicted to be structurally analogous to carbon‐only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine‐based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two‐dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long‐range, in‐plane order, while optical spectroscopy, X‐ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field‐effect transistors and light‐emitting diodes.
Mild Copper‐Catalyzed Fluorination of Alkyl Triflates with Potassium Fluoride
Authors: Dang Hester , Mailig Melrose , Lalic Gojko
Published: May 2014

A chemoselective catalytic fluorination of alkyl triflates is described using potassium fluoride as a fluoride source. Excellent yields of the desired alkyl fluorides are obtained after one hour at 45 °C using 2 mol % of the copper catalyst. With 10 mol % of the catalyst, full conversion can be achieved in less than 10 minutes at 45 °C, and thus makes this procedure potentially suited for the preparation of 18F‐labeled PET probes. As a result of the mild reaction conditions, only the substitution products are observed with no evidence of common side reactions, such as elimination. Reported is a preliminary study of the reaction scope, which demonstrates that the fluorination can be performed in the presence of a wide range of functional groups. Evidence suggests an unusual role of the [IPrCuOTf] catalyst as a phase‐transfer catalyst and points to [IPrCuF] as the active fluorinating reagent (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene).
Ultrathin WS2 Nanoflakes as a High‐Performance Electrocatalyst for the Hydrogen Evolution Reaction
Authors: Cheng Liang , Huang Wenjing , Gong Qiufang , Liu Changhai , Liu Zhuang , Li Yanguang , Dai Hongjie
Published: May 2014

Much has been done to search for highly efficient and inexpensive electrocatalysts for the hydrogen evolution reaction (HER), which is critical to a range of electrochemical and photoelectrochemical processes. A new, high‐temperature solution‐phase method for the synthesis of ultrathin WS2 nanoflakes is now reported. The resulting product possesses monolayer thickness with dimensions in the nanometer range and abundant edges. These favorable structural features render the WS2 nanoflakes highly active and durable catalysts for the HER in acids. The catalyst exhibits a small HER overpotential of approximately 100 mV and a Tafel slope of 48 mV/decade. These ultrathin WS2 nanoflakes represent an attractive alternative to the precious platinum benchmark catalyst and rival MoS2 materials that have recently been heavily scrutinized for the electrocatalytic HER.
Synthesis, Discovery, and Quantitation of Dihomo‐Isofurans: Biomarkers for In Vivo Adrenic Acid Peroxidation
Authors: de La Torre Aurélien , Lee Yiu Yiu , Oger Camille , Sangild Per Torp , Durand Thierry , Lee Jetty Chung‐Yung , Galano Jean‐Marie
Published: May 2014

The growing importance of lipidomics, and the interest of non‐enzymatic metabolites of polyunsaturated fatty acids (PUFAs) prompted us to initiate the synthesis of novel dihomo‐IsoF compounds. Such metabolites of adrenic acid, the main PUFA in white matter, were synthesized using a divergent approach based on an orthoester cyclization. LC‐MS/MS investigation on pig brains showed the potential of this novel biomarker for the first time, as a powerful new tool for brain lipid peroxidation assessment.
Access to Oxoquinoline Heterocycles by N‐Heterocyclic Carbene Catalyzed Ester Activation for Selective Reaction with an Enone
Authors: Fu Zhenqian , Jiang Ke , Zhu Tingshun , Torres Jaume , Chi Yonggui Robin
Published: May 2014

Organocatalytic ester activation is developed for a highly selective cascade reaction between saturated esters and amino enones. The reaction involves activation of the β‐carbon atom of the ester as a key step. This method allows a single‐step access to multicyclic oxoquinoline‐type heterocycles with high enantiomeric ratios.
Double CF Bond Activation through β‐Fluorine Elimination: Nickel‐Mediated [3+2] Cycloaddition of 2‐Trifluoromethyl‐1‐alkenes with Alkynes
Authors: Ichitsuka Tomohiro , Fujita Takeshi , Arita Tomohiro , Ichikawa Junji
Published: May 2014

The nickel‐mediated [3+2] cycloaddition of 2‐trifluoromethyl‐1‐alkenes with alkynes afforded fluorine‐containing multi‐substituted cyclopentadienes in a regioselective manner. This reaction involves the consecutive two CF bond cleavage of a trifluoromethyl or a pentafluoroethyl group through β‐fluorine elimination.
Rhodium(II)‐Catalyzed Intramolecular Cycloisomerizations of Methylenecyclopropanes with N‐Sulfonyl 1,2,3‐Triazoles
Authors: Chen Kai , Zhu Zi‐Zhong , Zhang Yong‐Sheng , Tang Xiang‐Ying , Shi Min
Published: May 2014

A novel rhodium(II)‐catalyzed tandem cycloisomerization of methylenecyclopropanes (MCPs) with N‐sulfonyl 1,2,3‐triazoles is disclosed. The reaction produces a series of highly functionalized polycyclic N heterocycles via a rhodium imino carbene intermediate. A distinct feature of this divergent synthesis is that different types of substrates control the reaction pathways. Moreover, several interesting transformations of these products to construct diazabicyclo[3.2.1]octane derivatives are also reported.
Luminous Butterflies: Efficient Exciton Harvesting by Benzophenone Derivatives for Full‐Color Delayed Fluorescence OLEDs
Authors: Lee Sae Youn , Yasuda Takuma , Yang Yu Seok , Zhang Qisheng , Adachi Chihaya
Published: May 2014

Butterfly‐shaped luminescent benzophenone derivatives with small energy gaps between their singlet and triplet excited states are used to achieve efficient full‐color delayed fluorescence. Organic light‐emitting diodes (OLEDs) with these benzophenone derivatives doped in the emissive layer can generate electroluminescence ranging from blue to orange–red and white, with maximum external quantum efficiencies of up to 14.3 %. Triplet excitons are efficiently harvested through delayed fluorescence channels.
Rhodium‐Catalyzed Asymmetric Arylation of β,γ‐Unsaturated α‐Ketoamides for the Construction of Nonracemic γ,γ‐Diarylcarbonyl Compounds
Authors: Wang Juanjuan , Wang Min , Cao Peng , Jiang Liyin , Chen Guihua , Liao Jian
Published: May 2014

A highly regio‐ and enantioselective rhodium‐catalyzed 1,4‐addition of arylboronic acids to β,γ‐unsaturated α‐ketoamides using a simple new chiral sulfinylphosphine ligand is described. This transformation provides an attractive approach to construct chiral nonracemic γ,γ‐diarylsubstituted carbonyl compounds, as exemplified in the concise syntheses of sertraline and tetrahydroquinoline‐2‐carboxylamide.
Abbau von Nitridoeisen(V)‐Komplexen durch N‐N‐Kupplung in Lösung: spektroskopische und theoretische Analyse
Authors: Krahe Oliver , Bill Eckhard , Neese Frank
Published: May 2014

Kryogen abgefangene FeV‐Nitrid‐Komplexe mit Cyclam‐basierten Liganden zerfallen in bimolekularen Reaktionen und bilden dabei ausschließlich FeII‐Verbindungen. Die Charakterisierung der Ausgangsverbindungen und Produkte durch Mößbauer‐Spektroskopie, Massenspektrometrie und DFT‐Rechnungen ergab, dass die Reaktion über eine reduktive Nitrid‐Kupplung und die Freisetzung von Distickstoff verläuft (2 FeVN → FeII‐NN‐FeII → 2 FeII+N2). Der Reaktionspfad, der einer “inversen” Haber‐Bosch‐Reaktion entspricht, wurde mit Computermethoden erforscht, auch um zu klären, ob die Umsetzung katalytisch aktives FeV(N) liefern könnte. Die Ergebnisse bieten Einblick in die photolytische Spaltung von FeIII‐Aziden, die zur Erzeugung von hochvalenten Fe‐Nitriden genutzt wird.
Total Synthesis and Stereochemical Reassignment of Mandelalide A
Authors: Lei Honghui , Yan Jialei , Yu Jie , Liu Yuqing , Wang Zhuo , Xu Zhengshuang , Ye Tao
Published: May 2014

The total synthesis of the tunicate metabolite mandelalide A and the correction of its originally assigned stereochemistry are reported. Key features of the convergent, fully stereocontrolled route include the use of a Prins cyclization for the diastereoselective construction of the tetrahydropyran subunit, Rychnovsky–Bartlett cyclization for the preparation of the tetrahydrofuran moiety, Suzuki coupling, Horner–Wadsworth–Emmons macrocyclization, and glycosylation to append the L‐rhamnose‐derived pyranoside.
Catalytic Enantioselective Nazarov Cyclization: Construction of Vicinal All‐Carbon‐Atom Quaternary Stereocenters
Authors: Jolit Anais , Walleser Patrick M. , Yap Glenn P. A. , Tius Marcus A.
Published: May 2014

The diastereoselective asymmetric synthesis of vicinal all‐carbon‐atom quaternary stereocenters is a challenging problem in organic synthesis for which only few solutions have been described. A catalytic asymmetric Nazarov cyclization of fully substituted dienones that provides cyclopentenone derivatives with vicinal quaternary stereocenters in high optical purity and as single diastereoisomers is now reported.
Furan‐Based o‐Quinodimethanes by Gold‐Catalyzed Dehydrogenative Heterocyclization of 2‐(1‐Alkynyl)‐2‐alken‐1‐ones: A Modular Entry to 2,3‐Furan‐Fused Carbocycles
Authors: Zhou Liejin , Zhang Mingrui , Li Wenbo , Zhang Junliang
Published: May 2014

A strategy for in situ generation of furan‐based ortho‐quinodimethanes (o‐QDMs) by the gold(I)‐mediated dehydrogenative heterocyclization of 2‐(1‐alkynyl)‐2‐alken‐1‐ones in the presence of pyridine N‐oxide under mild reaction conditions was developed. These in situ furan‐based o‐QDMs were trapped by electron‐deficient olefins and alkynes, thus furnishing various 2,3‐furan‐fused carbocycles in good yields with high diastereo‐ and regioselectivities.
Monobenzofused 1,4‐Azaborines: Synthesis, Characterization, and Discovery of a Unique Coordination Mode
Authors: Xu Senmiao , Haeffner Fredrik , Li Bo , Zakharov Lev N. , Liu Shih‐Yuan
Published: May 2014

We report the first general synthesis of boron‐substituted monobenzofused 1,4‐azaborines using ring‐closing metathesis of an enamine‐containing diene as a key synthetic strategy. As part of our investigations, we discovered that the B‐C3 moiety in a 1,4‐azaborine can serve uniquely as a η2‐L‐type ligand. This functionality is exemplified by two κ2‐N‐η2‐BC Pt complexes of a boron‐pyridyl‐substituted monobenzofused‐1,4‐azaborine. Single‐crystal X‐ray diffraction analysis of the Pt complexes shows a strong structural contribution from the iminium resonance form of the monobenzofused‐1,4‐azaborine ligand. We also demonstrate that a palladium(0) complex supported by a 1,4‐azaborine‐based phosphine ligand can catalyze hydroboration of 1‐buten‐3‐yne with unique selectivity. In view of the importance of arene–metal π‐interactions in catalytic applications, this work should open new opportunities for ligand design involving the 1,4‐azaborine motif as an arene substitute.
Total Syntheses of Hyperforin and Papuaforins A–C, and Formal Synthesis of Nemorosone through a Gold(I)‐Catalyzed Carbocyclization
Authors: Bellavance Gabriel , Barriault Louis
Published: May 2014

The remarkable biological activities of polyprenylated polycyclic acylphloroglucinols (PPAPs) combined with their highly decorated bicyclo[3.3.1]nonane‐2,4,9‐trione frameworks have inspired synthetic organic chemists over the last decade. The concise total syntheses of four natural products PPAPs; hyperforin and papuaforins A–C, and the formal synthesis of nemorosone are reported. Key to the realization of this strategy is the short and scalable synthesis of densely substituted PPAP scaffolds through a gold(I)‐catalyzed 6‐endo‐dig carbocyclization of cyclic enol ethers for late‐stage functionalization.
Cross‐Coupling Reactions between Stable Carbenes
Authors: Weinstein Cory M. , Martin Caleb D. , Liu Liu Leo , Bertrand Guy
Published: May 2014

By utilizing stable carbenes with low‐lying LUMOs, coupling with the stable nucleophilic diaminocyclopropenylidene was achieved. This reaction resulted in the formation of two new and rare examples of a bent allene as well as the isolation of the first carbene–carbene heterodimer.
Multifunctional, Defect‐Engineered Metal–Organic Frameworks with Ruthenium Centers: Sorption and Catalytic Properties
Authors: Kozachuk Olesia , Luz Ignacio , Llabrés i Xamena Francesc X. , Noei Heshmat , Kauer Max , Albada H. Bauke , Bloch Eric D. , Marler Bernd , Wang Yuemin , Muhler Martin , Fischer Roland A.
Published: May 2014

A mixed‐linker solid‐solution approach was employed to modify the metal sites and introduce structural defects into the mixed‐valence RuII/III structural analogue of the well‐known MOF family [M3II,II(btc)2] (M=Cu, Mo, Cr, Ni, Zn; btc=benzene‐1,3,5‐tricarboxylate), with partly missing carboxylate ligators at the Ru2 paddle‐wheels. Incorporation of pyridine‐3,5‐dicarboxylate (pydc), which is the same size as btc but carries lower charge, as a second, defective linker has led to the mixed‐linker isoreticular derivatives of Ru‐MOF, which display characteristics unlike those of the defect‐free framework. Along with the creation of additional coordinatively unsaturated sites, the incorporation of pydc induces the partial reduction of ruthenium. Accordingly, the modified Ru sites are responsible for the activity of the “defective” variants in the dissociative chemisorption of CO2, the enhanced performance in CO sorption, the formation of hydride species, and the catalytic hydrogenation of olefins.
Flexible Stereoselective Functionalizations of Ketones through Umpolung with Hypervalent Iodine Reagents
Authors: Mizar Pushpak , Wirth Thomas
Published: May 2014

The functionalization of carbonyl compounds in the α‐position has gathered much attention as a synthetic route because of the wide biological importance of such products. Through polarity reversal, or “umpolung”, we show here that typical nucleophiles, such as oxygen, nitrogen, and even carbon nucleophiles, can be used for addition reactions after tethering them to enol ethers. Our findings allow novel retrosynthetic planning and rapid assembly of structures previously accessible only by multistep sequences.
Decay of Iron(V) Nitride Complexes By a NN Bond‐Coupling Reaction in Solution: A Combined Spectroscopic and Theoretical Analysis
Authors: Krahe Oliver , Bill Eckhard , Neese Frank
Published: May 2014

Cryogenically trapped FeV nitride complexes with cyclam‐based ligands were found to decay by bimolecular reactions, forming exclusively FeII compounds. Characterization of educts and products by Mössbauer spectroscopy, mass spectrometry, and spectroscopy‐oriented DFT calculations showed that the reaction mechanism is reductive nitride coupling and release of dinitrogen (2 FeVN→FeII‐NN‐FeII→2 FeII+N2). The reaction pathways, representing an “inverse” of the Haber–Bosch reaction, were computationally explored in detail, also to judge the feasibility of yielding catalytically competent FeV(N). Implications for the photolytic cleavage of FeIII azides used to generate high‐valent Fe nitrides are discussed.