bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of Recent Dengue Exposure Among Malaria Parasite-Positive Children in Three Urban Centers in Ghana
Authors: Stoler Justin , Delimini Rupert K. , Bonney J. H. Kofi , Oduro Abraham R. , Owusu-Agyei Seth , Fobil Julius N. , Awandare Gordon A.
Published: January 2015

Blood samples of 218 children ages 2–14 years old with confirmed malaria in hospitals across Ghana were tested for dengue virus exposure. We detected dengue-specific immunoglobulin M (IgM) antibodies in 3.2% of the children, indicating possible coinfection, and IgG antibodies in 21.6% of them, which suggests previous exposure. Correlates of exposure are discussed.
La capacidad discursiva del diseño gráfico
Authors: Gamonal-Arroyo Roberto , García-García Francisco
Published: January 2015

Se investigan las relaciones existentes entre la retórica y el diseño gráfico. La comparación entre un orador clásico y un diseñador gráfico, entre un discurso y una pieza de diseño, nace de las conexiones entre ambas con la comunicación y con la creatividad. En este artículo se verá cómo una aplicación de los fundamentos de la retórica clásica puede abrir nuevas puertas tanto al ejercicio profesional como a la enseñanza del diseño gráfico y a la misma teoría de la retórica de la imagen.A través del análisis de un diseño gráfico se ejemplificarán los puntos de unión que nos muestran cómo los argumentos, las operaciones, las figuras y las fases del discurso retóricos están presentes en el proceso de creación del diseño gráfico y cómo los diseñadores, tal vez de manera inconsciente, emplean técnicas inspiradas en la retórica. Dicho de otro modo, el diseño gráfico es una construcción retórica.Se produce entonces una transposición de un modelo de creación del discurso mediante signos lingüísticos a un modelo de creación del discurso formado por signos visuales y tipográficos haciendo que el Diseño sea visto como una disciplina discursiva que va más allá del componente estético.
Relación de la obra del pintor Antonio López con la fotografía. Métodos de un maestro rechazado como profesor
Authors: Cabezas-Gelabert Lino , Oliver Joan Carles
Published: January 2015

En 1966 el pintor Antonio López fue rechazado en la Escuela Superior de Bellas Artes de San Fernando para acceder a la cátedra de “Preparatorio de colorido”, en donde presentó su Nevera de hielo. Después de cinco años de encargado de cátedra abandonó la institución. El artículo analiza las circunstancias de la prueba, en una década que supuso un cambio definitivo en su obra, hacia un realismo incómodo para un sistema que mantenía con dificultad la copia académica del modelo, una tradición difícilmente compatible con la abstracción que se imponía en la España de aquellos años. A la vez, las relaciones con la fotografía han condicionado las reflexiones teóricas del pintor y los métodos de trabajo analizados en estas páginas.
Mucinous cystadenoma of a horseshoe kidney: A case report and literature review
Authors: Mitome Taku , Yao Masahiro , Naoko Udaka , Fusayasu Shusei , Izumi Koji , Osaka Kimito , Hayashi Narihiko , Nakaigawa Noboru , Nagashima Yoji , Kubota Yoshinobu
Published: January 2015

A 45-year-old man complained of a palpable mass in his left abdomen. Computed tomography showed a horseshoe kidney with a Bosniak type II complicated cyst from a left segment. Three years after his initial examination, due to the growing cystic lesion and the compression imposed on the urinary collecting system and surrounding organs, we performed a left heminephrectomy. The diagnosis was mucinous cystadenoma of the kidney. No recurrence was observed 6 months after surgery. The histopathology was unique since the inner surface of the cyst was covered by a mucin-positive columnar epithelium connected to a urothelium, with continuous transition between the two. This suggests that the mucinous tumour may have originated from a sequestered segment of the renal pelvic epithelium in the renal parenchyma.
A rare cause of childhood renal cysts: Xp11.2 translocation renal cell carcinoma
Authors: Taşkınlar Hakan , Avlan Dinçer , Çıtak Çağlar , Polat Ayşe , Naycı Ali
Published: January 2015

Pediatric renal cysts are rare, usually asymptomatic and incidentally detected in children. Cyst associated renal cell carcinoma (RCC) or cystic RCC is extremely rare in children. Bosniak classification system has been accepted for the management of cystic renal masses. Xp11.2 translocation RCC is a recently classified distinct subtype and usually affects children and adolescents. We report the case of a 10-year-old girl with Xp11.2 translocation RCC from a cyst of the right kidney.
Stratospheric volcanic ash emissions from the 13 February 2014 Kelut eruption
Authors: Kristiansen N. I. , Prata A. J. , Stohl A. , Carn S. A.
Published: January 2015

Mount Kelut (Indonesia) erupted explosively around 15:50 UT on 13 February 2014 sending ash and gases into the stratosphere. Satellite ash retrievals and dispersion transport modeling are combined within an inversion framework to estimate the volcanic ash source term and to study ash transport. The estimated source term suggests that most of the ash was injected to altitudes of 16–17 km, in agreement with space‐based lidar data. Modeled ash concentrations along the flight track of a commercial aircraft that encountered the ash cloud indicate that it flew under the main ash cloud and encountered maximum ash concentrations of 9 ± 3 mg m−3, mean concentrations of 2 ± 1 mg m−3over a period of 10–11 min of the flight, giving a dosage of 1.2 ± 0.3 g s m−3. Satellite data could not be used directly to observe the ash cloud encountered by the aircraft, whereas inverse modeling revealed its presence.
Biomass burning dominates brown carbon absorption in the rural southeastern United States
Authors: Washenfelder R. A. , Attwood A. R. , Brock C. A. , Guo H. , Xu L. , Weber R. J. , Ng N. L. , Allen H. M. , Ayres B. R. , Baumann K. , Cohen R. C. , Draper D. C. , Duffey K. C. , Edgerton E. , Fry J. L. , Hu W. W. , Jimenez J. L. , Palm B. B. , Romer P. , Stone E. A. , Wooldridge P. J. , Brown S. S.
Published: January 2015

Brown carbon aerosol consists of light‐absorbing organic particulate matter with wavelength‐dependent absorption. Aerosol optical extinction, absorption, size distributions, and chemical composition were measured in rural Alabama during summer 2013. The field site was well located to examine sources of brown carbon aerosol, with influence by high biogenic organic aerosol concentrations, pollution from two nearby cities, and biomass burning aerosol. We report the optical closure between measured dry aerosol extinction at 365 nm and calculated extinction from composition and size distribution, showing agreement within experiment uncertainties. We find that aerosol optical extinction is dominated by scattering, with single‐scattering albedo values of 0.94 ± 0.02. Black carbon aerosol accounts for 91 ± 9% of the total carbonaceous aerosol absorption at 365 nm, while organic aerosol accounts for 9 ± 9%. The majority of brown carbon aerosol mass is associated with biomass burning, with smaller contributions from biogenically derived secondary organic aerosol.
Van Allen Probes observations linking radiation belt electrons to chorus waves during 2014 multiple storms
Authors: Liu Si , Xiao Fuliang , Yang Chang , He Yihua , Zhou Qinghua , Kletzing C. A. , Kurth W. S. , Hospodarsky G. B. , Spence H. E. , Reeves G. D. , Funsten H. O. , Blake J. B. , Baker D. N. , Wygant J. R.
Published: January 2015

During 18 February to 2 March 2014, the Van Allen Probes encountered multiple geomagnetic storms and simultaneously observed intensified chorus and hiss waves. During this period, there were substantial enhancements in fluxes of energetic (53.8–108.3 keV) and relativistic (2–3.6 MeV) electrons. Chorus waves were excited at locations L = 4–6.2 after the fluxes of energetic were greatly enhanced, with a lower frequency band and wave amplitudes ∼20–100 pT. Strong hiss waves occurred primarily in the main phases or below the location L = 4 in the recovery phases. Relativistic electron fluxes decreased in the main phases due to the adiabatic (e.g., the magnetopause shadowing) or nonadiabatic (hiss‐induced scattering) processes. In the recovery phases, relativistic electron fluxes either increased in the presence of enhanced chorus or remained unchanged in the absence of strong chorus or hiss. The observed relativistic electron phase space density peaked around L∗ = 4.5, characteristic of local acceleration. This multiple‐storm period reveals a typical picture that chorus waves are excited by the energetic electrons at first and then produce efficient acceleration of relativistic electrons. This further demonstrates that the interplay between both competing mechanisms of chorus‐driven acceleration and hiss‐driven scattering often occurs in the outer radiation belts.
Heat balances and thermally driven lagoon‐ocean exchangeson a tropical coral reef system (Moorea, French Polynesia)
Authors: Herdman Liv M. M. , Hench James L. , Monismith Stephen G.
Published: January 2015

The role of surface and advective heat fluxes on buoyancy‐driven circulation was examined within a tropical coral reef system. Measurements of local meteorological conditions as well as water temperature and velocity were made at six lagoon locations for 2 months during the austral summer. We found that temperature rather than salinity dominated buoyancy in this system. The data were used to calculate diurnally phase‐averaged thermal balances. A one‐dimensional momentum balance developed for a portion of the lagoon indicates that the diurnal heating pattern and consistent spatial gradients in surface heat fluxes create a baroclinic pressure gradient that is dynamically important in driving the observed circulation. The baroclinic and barotropic pressure gradients make up 90% of the momentum budget in part of the system; thus, when the baroclinic pressure gradient decreases 20% during the day due to changes in temperature gradient, this substantially changes the circulation, with different flow patterns occurring during night and day. Thermal balances computed across the entire lagoon show that the spatial heating patterns and resulting buoyancy‐driven circulation are important in maintaining a persistent advective export of heat from the lagoon and for enhancing ocean‐lagoon exchange.
Invisible polynyas: Modulation of fast ice thickness by ocean heat flux on the Canadian polar shelf
Authors: Melling Humfrey , Haas Christian , Brossier Eric
Published: January 2015

Although the Canadian polar shelf is dominated by thick fast ice in winter, areas of young ice or open water do recur annually at locations within and adjacent to the fast ice. These polynyas are detectable by eye and sustained by wind or tide‐driven ice divergence and ocean heat flux. Our ice‐thickness surveys by drilling and towed electromagnetic sounder reveal that visible polynyas comprise only a subset of thin‐ice coverage. Additional area in the coastal zone, in shallow channels and in fjords is covered by thin ice which is too thick to be discerned by eye. Our concurrent surveys by CTD reveal correlation between thin fast ice and above‐freezing seawater beneath it. We use winter time series of air and ocean temperatures and ice and snow thicknesses to calculate the ocean‐to‐ice heat flux as 15 and 22 W/m2 at locations with thin ice in Penny Strait and South Cape Fjord, respectively. Near‐surface seawater above freezing is not a sufficient condition for ocean heat to reach the ice; kinetic energy is needed to overcome density stratification. The ocean's isolation from wind under fast ice in winter leaves tides as the only source. Two tidal mechanisms driving ocean heat flux are discussed: diffusion via turbulence generated by shear at the under‐ice and benthic boundaries, and the internal hydraulics of flow over topography. The former appears dominant in channels and the coastal zone and the latter in some silled fjords where and when the layering of seawater density permits hydraulically critical flow.
Regional modeling of surface‐atmosphere interactions and their impact on Great Lakes hydroclimate
Authors: Bryan A. M. , Steiner A. L. , Posselt D. J.
Published: January 2015

Land and water surfaces play a critical role in hydroclimate by supplying moisture to the atmosphere, yet the ability of climate models to capture their feedbacks with the atmosphere relative to large‐scale transport is uncertain. To assess these land‐lake‐atmosphere feedbacks, we compare the controls on atmospheric moisture simulated by a regional climate model (RegCM) with observations and reanalysis products for the Great Lakes region. Three 23 year simulations, driven by one reanalysis product and two general circulation models, are performed. RegCM simulates wetter winters and drier summers than observed by up to 31 and 21%, respectively. Moisture advection exhibits similar biases, suggesting the contribution of external sources. Land surface fluxes account for nearly one third of summer precipitation according to two reanalysis products. RegCM underestimates reanalysis evapotranspiration by nearly 50%; however, the reanalyses overestimate measurements at three FLUXNET sites by up to a factor of 2, which may explain the model‐reanalysis differences. Neither RegCM nor the reanalyses capture the spatial variability in land evapotranspiration observed across the three FLUXNET sites, indicating a source of model uncertainty. In addition, RegCM underestimates the observed evapotranspiration response to its atmospheric drivers such as vapor pressure deficit and temperature. Over the lakes, one model member overestimates convective precipitation caused by enhanced evaporation under warm lake surface temperatures, highlighting the need for accurate representation of lake temperature in the surface boundary condition. We conclude that climate models, including those driving reanalyses, underestimate the observed surface‐atmosphere feedbacks and their influence on regional hydroclimate.
Optical progression characteristics of an interesting natural downward bipolar lightning flash
Authors: Chen Luwen , Lu Weitao , Zhang Yijun , Wang Daohong
Published: January 2015

Using high‐speed cameras, Lightning Attachment Process Observation Systems, and fast and slow electrical antennas, we documented a downward bipolar lightning flash that contained one first positive stroke with a peak current of 142 kA and five subsequent negative strokes hitting on a 90 m tall structure on 29 July 2010 in Guangzhou City, China. All the six strokes propagated along the same viewed channel established by the first positive return stroke. The leader which preceded the positive return stroke propagated downward without any branches at a two‐dimensional (2‐D) speed of 2.5 × 106 m/s. An upward connecting leader with a length of about 80 m was observed in response to the downward positive leader. The 10–90% risetimes of the return strokes' optical pulses ranged from 2.2 µs to 3.2 µs, while the widths from the 10% wavefront to the 50% wave tail ranged from 56.5 µs to 83.1 µs, and the half peak widths ranged from 53.4 µs to 81.6 µs. All the return strokes exhibited similar speeds, ranging from 1.0 × 108 m/s to 1.3 × 108 m/s. Each of the return strokes was followed by a continuing current stage (CC). The first positive stroke CC lasted more than 150 ms, much larger than all the subsequent negative stroke CC, ranging from 13 ms to 70 ms.
Isotope partitioning of soil respiration: A Bayesian solution to accommodate multiple sources of variability
Authors: Ogle Kiona , Pendall Elise
Published: January 2015

Isotopic methods offer great potential for partitioning trace gas fluxes such as soil respiration into their different source contributions. Traditional partitioning methods face challenges due to variability introduced by different measurement methods, fractionation effects, and end‐member uncertainty. To address these challenges, we describe a hierarchical Bayesian (HB) approach for isotopic partitioning of soil respiration that directly accommodates such variability. We apply our HB method to data from an experiment conducted in a shortgrass steppe ecosystem, where decomposition was previously shown to be stimulated by elevated CO2. Our approach simultaneously fits Keeling plot (KP) models to observations of soil or soil‐respired δ13C and [CO2] obtained via chambers and gas wells, corrects the KP intercepts for apparent fractionation (Δ) due to isotope‐specific diffusion rates and/or method artifacts, estimates method‐ and treatment‐specific values for Δ, propagates end‐member uncertainty, and calculates proportional contributions from two distinct respiration sources (“old” and “new” carbon). The chamber KP intercepts were estimated with greater confidence than the well intercepts and compared to the theoretical value of 4.4‰, our results suggest that Δ varies between 2 and 5.2‰ depending on method (chambers versus wells) and CO2 treatment. Because elevated CO2 plots were fumigated with 13C‐depleted CO2, the source contributions were tightly constrained, and new C accounted for 64% (range = 55–73%) of soil respiration. The contributions were less constrained for the ambient CO2 treatments, but new C accounted for significantly less (47%, range = 15–82%) of soil respiration. Our new HB partitioning approach contrasts our original analysis (higher contribution of old C under elevated CO2) because it uses additional data sources, accounts for end‐member bias, and estimates apparent fractionation effects.
Survival and severity in dominant cerebellar ataxias
Authors: Monin Marie‐Lorraine , Tezenas du Montcel Sophie , Marelli Cecilia , Cazeneuve Cecile , Charles Perrine , Tallaksen Chantal , Forlani Sylvie , Stevanin Giovanni , Brice Alexis , Durr Alexandra
Published: January 2015

Inherited spinocerebellar ataxias (SCAs) are known to be genetically and clinically heterogeneous. Whether severity and survival are variable, however, is not known. We, therefore, studied survival and severity in 446 cases and 509 relatives with known mutations. Survival was 68 years [95% CI: 65–70] in 223 patients with polyglutamine expansions versus 80 years [73–84] in 23 with other mutations (P < 0.0001). Disability was also more severe in the former: at age 60, 30% were wheelchair users versus 3% with other SCAs (P < 0.001). This has implications for genetic counseling and the design of therapeutic trials.
Classification of Systemic Lupus Erythematosus: Systemic Lupus International Collaborating Clinics Versus American College of Rheumatology Criteria. A Comparative Study of 2,055 Patients From a Real‐Life, International Systemic Lupus Erythematosus Cohort
Authors: Inês Luís , Silva Cândida , Galindo Maria , López‐Longo Francisco J. , Terroso Georgina , Romão Vasco C. , Rúa‐Figueroa Iñigo , Santos Maria J. , Pego‐Reigosa José M. , Nero Patrícia , Cerqueira Marcos , Duarte Cátia , Miranda Luís C. , Bernardes Miguel , Gonçalves Maria J. , Mouriño‐Rodriguez Coral , Araújo Filipe , Raposo Ana , Barcelos Anabela , Couto Maura , Abreu Pedro , Otón‐Sanchez Teresa , Macieira Carla , Ramos Filipa , Branco Jaime C. , Silva José A. P. , Canhão Helena , Calvo‐Alén Jaime ,   for the Rheumatic Diseases Registry of the Portuguese Society of Rheumatology,   the Registry of systemic Lupus Erythematosus Patients of the Spanish Society of Rheumatology
Published: January 2015

Objective

The new Systemic Lupus International Collaborating Clinics (SLICC) 2012 classification criteria aimed to improve the performance of systemic lupus erythematosus (SLE) classification over the American College of Rheumatology (ACR) 1997 criteria. However, the SLICC 2012 criteria need further external validation. Our objective was to compare the sensitivity for SLE classification between the ACR 1997 and the SLICC 2012 criteria sets in a real‐life, multicenter, international SLE population.

Methods

We conducted a cross‐sectional observational study of patients with a clinical diagnosis of SLE followed at the participating rheumatology centers and registered in the Portuguese and Spanish national registries. The sensitivity of the 2 classification sets was compared using McNemar's test. The sensitivity of ACR 1997 and SLICC 2012 was further examined in 5 subgroups, defined according to disease duration.

Results

We included 2,055 SLE patients (female 91.4%, white 93.5%, mean ± SD age at disease onset 33.1 ± 14.4 years, mean ± SD age at SLE diagnosis 35.3 ± 14.7 years, and mean ± SD age at the time of the study 47.4 ± 14.6 years) from 17 centers. The sensitivity for SLE classification was higher with the SLICC 2012 than with the ACR 1997 (93.2% versus 85.6%; P < 0.0001). Of 296 patients not fulfilling the ACR 1997, 62.8% could be classified with the SLICC 2012. The subgroup of patients with ≤5 years since disease onset presented the largest difference in sensitivity between the SLICC 2012 and the ACR 1997 (89.3% versus 76.0%; P < 0.0001); this difference diminished with longer disease duration, and it was no longer significant for patients with >20 years of disease duration.

Conclusion

The SLICC 2012 criteria were more sensitive than the ACR 1997 criteria in real‐life clinical practice in SLE. The SLICC 2012 criteria may allow patients to be classified as having SLE earlier in the disease course.
Continued Participation in a Ten‐Year Tight Control Treat‐to‐Target Study in Rheumatoid Arthritis: Why Keep Patients Doing their Best?
Authors: Markusse Iris M. , Dirven Linda , Han K. Huub , Ronday H. Karel , Kerstens Pit J. S. M. , Lems Willem F. , Huizinga Tom W. J. , Allaart Cornelia F.
Published: January 2015

Objective

To identify risk factors for early study termination and motivators for adherence to a long‐term followup trial and to improve completeness of long‐term studies.

Methods

Risk factors for early termination in 508 included patients were identified through Cox regression analysis. Patients completing the 10‐year followup filled in a questionnaire on possible motives for continued study participation.

Results

Risk factors for early termination were higher age (hazard ratio [HR] 1.03, 95% confidence interval [95% CI] 1.02–1.04), functional disability during the preceding year (HR 1.54, 95% CI 1.20–1.99), having achieved drug‐free remission (HR 6.62, 95% CI 2.07–21.14), limited joint damage (HR 0.98, 95% CI 0.97–0.995 for actual damage; HR 0.83, 95% CI 0.73–0.94 for damage progression), and few adverse events (HR 0.35, 95% CI 0.26–0.47). A total of 288 of 313 patients (92%) attending the last visit answered the questionnaire. The majority mentioned contributing to scientific research (97% agreed), helping other patients (91%), and learning about new treatment strategies (84%) and their disease (85%) as reasons to continue participation. Next, patients mentioned tight control (202 of 278 patients), good treatment strategy (128 of 278), good medication (117 of 278), and good half‐term results (102 of 278) as motivators. More than 95% of patients experienced participation “as expected” or “better than expected.” Additional examinations during yearly visits (extra questionnaires, imaging) were mentioned as “worse than expected” (10%), as was answering routine questionnaires (7%).

Conclusion

Continued participation was relatively high in the Treatment Strategies for Rheumatoid Arthritis (BeSt) Study. Higher age, functional disability, drug‐free remission, little joint damage, and few adverse events predicted early study termination. Main motives for continued participation were a willingness to contribute to research, help future patients, and because patients had good experiences with the study protocol.
Preparation and Characterization of Low Polymerization Shrinkage and Bis‐GMA‐Free Dental Resin System
Authors: Yuan Shuang , Liu Fang , He Jingwei
Published: January 2015

Because of the estrogenic effect of bisphenol A (BPA), the application of BPA derivatives such as Bis‐GMA in dentistry has been doubted. In this research, Bis‐GMA‐free dental resin systems were prepared by mixing 1,6‐bis(2′‐methacryloyoxy‐ethoxycarbonyl‐amino)‐2,4,4‐trimethylhexane (UDMA), silicon containing dimethacrylate monomer (SiMA), and triethyleneglycol dimethacrylate (TEGDMA) together with different mass fraction. Double bond conversion, polymerization shrinkage, flexural strength, flexural, water sorption, and water solubility of prepared resins were investigated. Results showed that when UDMA/SiMA/TEGDMA was present in the ratio of 9:1:10 (wt/wt/wt), the obtained resin had the best comprehensive physicochemical properties and potential to be used as Bis‐GMA‐free dental resin.
Extreme Carbon Dioxide Sorption Hysteresis in Open‐Channel Rigid Metal–Organic Frameworks
Authors: Bezuidenhout Charl X. , Smith Vincent J. , Bhatt Prashant M. , Esterhuysen Catharine , Barbour Leonard J.
Published: January 2015

A systematic study is presented of three closely related microporous metal‐organic frameworks the pore dimensions of which vary according to the choice of 4,4′‐bipyridyl linker. The tunable linker allows exploration of the effect of increasing pore dimensions on the sorption behavior of the frameworks. The MOFs described capture CO2 under supercritical conditions and continue to sequester the gas under ambient conditions. Gas sorption isotherms for CO2 are compared with thermogravimetric data, and the CO2 molecules in the channels of the frameworks could be modeled using single‐crystal X‐ray diffraction analysis. Crystallographic data were used to construct a theoretical model based on DFT methods to calculate framework electrostatic potential maps with a view to understanding the nature of the sorbate–sorbent interactions.
A Nanoparticle Catalyst for Heterogeneous Phase Para‐Hydrogen‐Induced Polarization in Water
Authors: Glöggler Stefan , Grunfeld Alexander M. , Ertas Yavuz N. , McCormick Jeffrey , Wagner Shawn , Schleker P. Philipp M. , Bouchard Louis‐S.
Published: January 2015

Para‐hydrogen‐induced polarization (PHIP) is a technique capable of producing spin polarization at a magnitude far greater than state‐of‐the‐art magnets. A significant application of PHIP is to generate contrast agents for biomedical imaging. Clinically viable and effective contrast agents not only require high levels of polarization but heterogeneous catalysts that can be used in water to eliminate the toxicity impact. Herein, we demonstrate the use of Pt nanoparticles capped with glutathione to induce heterogeneous PHIP in water. The ligand‐inhibited surface diffusion on the nanoparticles resulted in a 1H polarization of P=0.25 % for hydroxyethyl propionate, a known contrast agent for magnetic resonance angiography. Transferring the 1H polarization to a 13C nucleus using a para‐hydrogen polarizer yielded a polarization of 0.013 %. The nuclear‐spin polarizations achieved in these experiments are the first reported to date involving heterogeneous reactions in water.
Enhanced Electron Penetration through an Ultrathin Graphene Layer for Highly Efficient Catalysis of the Hydrogen Evolution Reaction
Authors: Deng Jiao , Ren Pengju , Deng Dehui , Bao Xinhe
Published: January 2015

Major challenges encountered when trying to replace precious‐metal‐based electrocatalysts of the hydrogen evolution reaction (HER) in acidic media are related to the low efficiency and stability of non‐precious‐metal compounds. Therefore, new concepts and strategies have to be devised to develop electrocatalysts that are based on earth‐abundant materials. Herein, we report a hierarchical architecture that consists of ultrathin graphene shells (only 1–3 layers) that encapsulate a uniform CoNi nanoalloy to enhance its HER performance in acidic media. The optimized catalyst exhibits high stability and activity with an onset overpotential of almost zero versus the reversible hydrogen electrode (RHE) and an overpotential of only 142 mV at 10 mA cm−2, which is quite close to that of commercial 40 % Pt/C catalysts. Density functional theory (DFT) calculations indicate that the ultrathin graphene shells strongly promote electron penetration from the CoNi nanoalloy to the graphene surface. With nitrogen dopants, they synergistically increase the electron density on the graphene surface, which results in superior HER activity on the graphene shells.
Direct Asymmetric Dearomatization of 2‐Naphthols by Scandium‐Catalyzed Electrophilic Amination
Authors: Nan Jiang , Liu Jingjing , Zheng Huayu , Zuo Zhijun , Hou Lei , Hu Huaiming , Wang Yaoyu , Luan Xinjun
Published: January 2015

Catalytic asymmetric aminative dearomatization of 1‐substituted 2‐naphthols was successfully implemented with electrophilic azodicarboxylates under the catalysis of chiral ScIII/pybox complexes. This intermolecular reaction represents a hitherto unknown enantioselective CN bond‐forming process through direct dearomatization of phenolic compounds to generate chiral nitrogen‐containing quaternary carbon stereocenters.
Vielseitige Farbstoffsynthesen durch mehrfache Kondensationsreaktionen von Acetylanilinen mit Perylenanhydriden
Authors: Jänsch Daniel , Li Chen , Chen Long , Wagner Manfred , Müllen Klaus
Published: January 2015

Mit der Transformation von Rylenen zu neuen Chromophorfamilien wird ein weiterer Schlüsselschritt der Rylenchemie vorgestellt. Die Imidierung von Rylenanhydriden mit 2‐Acetylanilinen kann durch die Wahl des Lösungsmittels dahingehend gesteuert werden, dass eine Umsetzung entweder zu einer 4‐Hydroxychinolin‐ (4‐HQ) oder einer 4‐Oxochinolineinheit (4‐OQ) erfolgt. Das 4‐HQ‐Motiv enthält eine Aminoenongruppe, die durch eine intramolekulare Aldolkondensation gebildet wird und damit das erste vinyloge Rylenimid darstellt. Das Konzept der Vinylogisierung wird durch die Verwendung von 2,6‐Diacetylanilin weiter entwickelt, wodurch ein 3a‐Aza‐1,6‐phenalendion‐erweitertes Rylengerüst mit vollständig eingebettetem Stickstoffatom erhalten wird. Durch Funktionalisierung der Aminoenonfunktionen, z. B. durch Malonsäuredinitriladdition, können die optischen und elektronischen Eigenschaften weiter modifiziert werden.
Simplified Electrochemically Mediated Atom Transfer Radical Polymerization using a Sacrificial Anode
Authors: Park Sangwoo , Chmielarz Paweł , Gennaro Armando , Matyjaszewski Krzysztof
Published: January 2015

Simplification of electrochemically mediated atom transfer radical polymerization was achieved efficiently under either potentiostatic or galvanostatic conditions using an aluminum wire sacrificial anode (seATRP) immersed directly into the reaction flask without separating the counter electrode. seATRP polymerizations were carried out under different applied potentials, Eapps=E1/2, Epc, Epc −40 mV, and Epc −80 mV. As the rate of polymerization (Rp) can be modulated by applying different Eapp potentials, more reducing conditions resulted in faster Rp. The polymerization results showed similar narrow molecular‐weight distribution throughout the reactions, similar to results observed for n‐butyl acrylate (BA) polymerization under conventional eATRP. High‐molecular‐weight PBA and diblock copolymers were synthesized by seATRP with more than 90 % monomer conversion. Furthermore, galvanostatic conditions were developed for synthesizing PBA with the two‐electrode system.
Isolation of a Hydrogen‐Bonded Complex Based on the Anthranol/Anthroxyl Pair: Formation of a Hydrogen‐Atom Self‐Exchange System
Authors: Hirao Yasukazu , Saito Tohru , Kurata Hiroyuki , Kubo Takashi
Published: January 2015

A hydrogen‐bonded complex was successfully isolated as crystals from the anthranol/anthroxyl pair in the self‐exchange proton‐coupled electron transfer (PCET) reaction. The anthroxyl radical was stabilized by the introduction of a 9‐anthryl group at the carbon atom at the 10‐position. The hydrogen‐bonded complex with anthranol self‐assembled by π–π stacking to form a one‐dimensional chain in the crystal. The conformation around the hydrogen bond was similar to that of the theoretically predicted PCET activated complex of the phenol/phenoxyl pair. X‐ray crystal analyses revealed the self‐exchange of a hydrogen atom via the hydrogen bond, indicating the activation of the self‐exchange PCET reaction between anthranol and anthroxyl. Magnetic measurements revealed that magnetic ordering inside the one‐dimensional chain caused the inactivation of the self‐exchange reaction.
The Nature of Photocatalytic “Water Splitting” on Silicon Nanowires
Authors: Liu Dong , Li Leilei , Gao Yang , Wang Chengming , Jiang Jun , Xiong Yujie
Published: January 2015

Silicon should be an ideal semiconductor material if it can be proven usable for photocatalytic water splitting, given its high natural abundance. Thus it is imperative to explore the possibility of water splitting by running photocatalysis on a silicon surface and to decode the mechanism behind it. It is reported that hydrogen gas can indeed be produced from Si nanowires when illuminated in water, but the reactions are not a real water‐splitting process. Instead, the production of hydrogen gas on the Si nanowires occurs through the cleavage of SiH bonds and the formation of SiOH bonds, resulting in the low probability of generating oxygen. On the other hand, these two types of surface dangling bonds both extract photoexcited electrons, whose competition greatly impacts on carrier lifetime and reaction efficiency. Thus surface chemistry holds the key to achieving high efficiency in such a photocatalytic system.
Atomically Thin Arsenene and Antimonene: Semimetal–Semiconductor and Indirect–Direct Band‐Gap Transitions
Authors: Zhang Shengli , Yan Zhong , Li Yafei , Chen Zhongfang , Zeng Haibo
Published: January 2015

The typical two‐dimensional (2D) semiconductors MoS2, MoSe2, WS2, WSe2 and black phosphorus have garnered tremendous interest for their unique electronic, optical, and chemical properties. However, all 2D semiconductors reported thus far feature band gaps that are smaller than 2.0 eV, which has greatly restricted their applications, especially in optoelectronic devices with photoresponse in the blue and UV range. Novel 2D mono‐elemental semiconductors, namely monolayered arsenene and antimonene, with wide band gaps and high stability were now developed based on first‐principles calculations. Interestingly, although As and Sb are typically semimetals in the bulk, they are transformed into indirect semiconductors with band gaps of 2.49 and 2.28 eV when thinned to one atomic layer. Significantly, under small biaxial strain, these materials were transformed from indirect into direct band‐gap semiconductors. Such dramatic changes in the electronic structure could pave the way for transistors with high on/off ratios, optoelectronic devices working under blue or UV light, and mechanical sensors based on new 2D crystals.
Nitrosopurines En Route to Potently Cytotoxic Asmarines
Authors: Wan Kanny K. , Iwasaki Kotaro , Umotoy Jeffrey C. , Wolan Dennis W. , Shenvi Ryan A.
Published: January 2015

A nitrosopurine ene reaction easily assembles the asmarine pharmacophore and transmits remote stereochemistry to the diazepine‐purine hetereocycle. This reaction generates potent cytotoxins which exceed the potency of asmarine A (1.2 μM IC50) and supersede the metabolites as useful leads for biological discovery.
Copper as a Robust and Transparent Electrocatalyst for Water Oxidation
Authors: Du Jialei , Chen Zuofeng , Ye Shengrong , Wiley Benjamin J. , Meyer Thomas J.
Published: January 2015

Copper metal is in theory a viable oxidative electrocatalyst based on surface oxidation to CuIII and/or CuIV, but its use in water oxidation has been impeded by anodic corrosion. The in situ formation of an efficient interfacial oxygen‐evolving Cu catalyst from CuII in concentrated carbonate solutions is presented. The catalyst necessitates use of dissolved CuII and accesses the higher oxidation states prior to decompostion to form an active surface film, which is limited by solution conditions. This observation and restriction led to the exploration of ways to use surface‐protected Cu metal as a robust electrocatalyst for water oxidation. Formation of a compact film of CuO on Cu surface prevents anodic corrosion and results in sustained catalytic water oxidation. The Cu/CuO surface stabilization was also applied to Cu nanowire films, which are transparent and flexible electrocatalysts for water oxidation and are an attractive alternative to ITO‐supported catalysts for photoelectrochemical applications.
Structural Characterization of O‐ and C‐Glycosylating Variants of the Landomycin Glycosyltransferase LanGT2
Authors: Tam Heng Keat , Härle Johannes , Gerhardt Stefan , Rohr Jürgen , Wang Guojun , Thorson Jon S. , Bigot Aurélien , Lutterbeck Monika , Seiche Wolfgang , Breit Bernhard , Bechthold Andreas , Einsle Oliver
Published: January 2015

The structures of the O‐glycosyltransferase LanGT2 and the engineered, CC bond‐forming variant LanGT2S8Ac show how the replacement of a single loop can change the functionality of the enzyme. Crystal structures of the enzymes in complex with a nonhydrolyzable nucleotide‐sugar analogue revealed that there is a conformational transition to create the binding sites for the aglycon substrate. This induced‐fit transition was explored by molecular docking experiments with various aglycon substrates.
Rhodium‐Catalyzed (5+1) Annulations Between 2‐Alkenylphenols and Allenes: A Practical Entry to 2,2‐Disubstituted 2H‐Chromenes
Authors: Casanova Noelia , Seoane Andrés , Mascareñas José L. , Gulías Moisés
Published: January 2015

Readily available alkenylphenols react with allenes under rhodium catalysis to provide valuable 2,2‐disubstituted 2H‐chromenes. The whole process, which involves the cleavage of one CH bond of the alkenyl moiety and the participation of the allene as a one‐carbon cycloaddition partner, can be considered a simple, versatile, and atom‐economical (5+1) heteroannulation. The reaction tolerates a broad range of substituents both in the alkenylphenol and in the allene, and most probably proceeds through a mechanism involving a rhodium‐catalyzed CC coupling followed by two sequential pericyclic processes.
Visible‐Light‐Driven CO2 Reduction with Carbon Nitride: Enhancing the Activity of Ruthenium Catalysts
Authors: Kuriki Ryo , Sekizawa Keita , Ishitani Osamu , Maeda Kazuhiko
Published: January 2015

A heterogeneous photocatalyst system that consists of a ruthenium complex and carbon nitride (C3N4), which act as the catalytic and light‐harvesting units, respectively, was developed for the reduction of CO2 into formic acid. Promoting the injection of electrons from C3N4 into the ruthenium unit as well as strengthening the electronic interactions between the two units enhanced its activity. The use of a suitable solvent further improved the performance, resulting in a turnover number of greater than 1000 and an apparent quantum yield of 5.7 % at 400 nm. These are the best values that have been reported for heterogeneous photocatalysts for CO2 reduction under visible‐light irradiation to date.
Structural aspects of mechanical properties of iPP‐based composites. I. Composite iPP fibers with VGCF nanofiller
Authors: Ivan'kova Elena , Kasatkin Igor , Moskalyuk Olga , Yudin Vladimir , Kenny Jose Maria
Published: January 2015

Nanocomposite fibers consisting of isotactic polypropylene (iPP) as a matrix filled with vapor grown carbon nanofibers (VGCF) have been prepared and their fine crystalline structure and mechanical properties characterized. The obtained results point out that the VGCF oriented along the fiber extrusion direction induce crystallization in the surrounding iPP matrix in a special way leading to the formation of oriented iPP α‐transcrystallite layers. The VGCF content and the draw ratio (DR) affect the textural properties of the composite material and lead to the formation of an anisotropic structure. The improvements of the mechanical properties of the composite fibers in both undrawn and drawn states are attributed to the VGCF aligning effect during extrusion, which produces highly oriented iPP crystalline structure, rather than to the reinforcing effect of the nanofibers. A new detailed scheme explaining the changes in tensile strength from the structural point of view is proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41865.
Study on poly(butylene adipate‐co‐terephthalate)/starch composites with polymeric methylenediphenyl diisocyanate
Authors: Kim Ji‐Hoo , Lee Jae Choon , Kim Gue‐Hyun
Published: January 2015

To lower the cost of poly(butylene adipate‐co‐terephthalate) or PBAT, starch was used as a filler in this study. To increase tensile strength of PBAT/starch composites, polymeric methylenediphenyl diisocyanate (pMDI) was used as a compatibilizer. PBAT was melt‐mixed with starch in a kneader, and then the mixtures were compression‐molded. The effects of starch and pMDI content on the tensile strength and elongation at break of PBAT/starch composites were examined. The morphology and biodegradability of the composites in soil were also studied. The tensile strength of PBAT and PBAT/starch composites increases with increasing content of pMDI. The increase of weight average molecular weight of PBAT and improved interaction between PBAT and starch were observed with increasing content of pMDI. The weight average molecular weights of buried PBAT and the composites in soil significantly decrease. Especially, the reduction of the weight average molecular weight of PBAT/starch (70/30) composite is the most significant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41884.
Brief Report: Successful In Vitro Culture of Rheumatoid Arthritis Synovial Tissue Explants at the Air–Liquid Interface
Authors: Sakuraba Koji , Fujimura Kenjiro , Nakashima Yasuharu , Okazaki Ken , Fukushi Jun‐ichi , Ohishi Masanobu , Oyamada Akiko , Esaki Yukio , Miyahara Hisaaki , Iwamoto Yukihide , Yoshikai Yasunobu , Yamada Hisakata
Published: January 2015

Objective

To establish a method to culture synovial tissue explants from patients with rheumatoid arthritis (RA).

Methods

Synovial tissue explants obtained from 10 patients with RA were cultured at the air–liquid interface or were submerged in culture medium. As a control, synovial explants were engrafted subcutaneously into SCID mice. The synovial explants were harvested at different time points, and histologic or flow cytometric analysis was performed. Cytokine levels in the culture supernatants were measured by enzyme‐linked immunosorbent assay. Infliximab was added to the air–liquid interface culture to evaluate the effect of tumor necrosis factor α blockade on inflammatory cytokine production.

Results

The histologic features of RA synovitis, including a hyperplastic lining layer and the presence of cellular infiltrate in the sublining layer, were maintained in synovial tissue explants in air–liquid interface culture. In synovial grafts harvested from SCID‐HuRAg mice, the cellular infiltrate was well maintained in the sublining, but the lining layer was lost. Viable CD4+ T cells and macrophages were abundant after air–liquid interface culture but were virtually absent after submerged culture. Furthermore, synovial tissue explants in air–liquid interface culture produced interleukin‐6 (IL‐6) and IL‐8 for a prolonged period of time. The addition of infliximab effectively reduced cytokine production.

Conclusion

RA synovial explants can be maintained for weeks using an air–liquid interface culture. This simple culture system might be useful for analyzing the pathogenesis of RA synovitis and for developing antirheumatic drugs.
An Electrochemical Strategy to Measure the Thickness of Electroactive Microbial Biofilms
Authors: Millo Diego
Published: January 2015

The study of electroactive microbial biofilms often requires knowledge of the biofilm thickness. Unfortunately, this parameter is, nowadays, only accessible through expensive microscopic techniques. This work overcomes this limitation by presenting a new strategy, exploiting the use of chronoamperometry (CA) alone. A mixed‐culture biofilm is exposed to an O2‐saturated solution during anode respiration to suppress its catalytic activity. Assuming that inactivation of the electrocatalytic process is caused by O2 diffusion through the biofilm, a simple relation allows the use of the time constant extracted from the fitting of the curve of the CA trace during inactivation for the straightforward and quantitative determination of biofilm thickness. The biofilm thickness obtained with this method obeys the expected trend reported for biofilm growth and is in agreement with optical measurements. Contrary to the techniques usually employed to determine biofilm thickness, this new strategy is very rapid, nondisruptive, inexpensive, and may become a convenient alternative with respect to expensive and time‐consuming microscopic techniques.
Modular Synthesis of Linear Bis‐ and Tris‐monodentate Fused [6]Polynorbornane‐Based Ligands and their Assembly into Coordination Cages
Authors: Johnstone Mark D. , Schwarze Eike K. , Clever Guido H. , Pfeffer Frederick M.
Published: January 2015

A modular approach has been developed for the synthesis of rigid linear di‐ and tritopic ligands based on a fused [6]polynorbornane scaffold. The design provides up to three sites for installing functionality, including both “ends” and a “central” position with the advantage that each region can be independently addressed during synthesis. To illustrate the utility of the approach, both pyridyl and picolyl units were incorporated to provide six new ligands, with centers and ends either matched or mismatched. Indeed, both [M2L4] cages with endohedral functionality and [M3L4] complexes were cleanly produced from these ligands with assembled structures confirmed by using 1H NMR spectroscopy, HRMS, and molecular modelling.
Extending the Substrate Scope of Bicyclic P‐Oxazoline/Thiazole Ligands for Ir‐Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group
Authors: Biosca Maria , Paptchikhine Alexander , Pàmies Oscar , Andersson Pher G. , Diéguez Montserrat
Published: January 2015

This study identifies a series of Ir‐bicyclic phosphoroamidite–oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E‐ and Z‐tri‐ and disubstituted substrates, vinylsilanes, enol phosphinates, tri‐ and disubstituted alkenylboronic esters, and α,β‐unsaturated enones) in high enantioselectivities (ee values up to 99 %) and conversions. The design of the new phosphoroamidite–oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N‐phosphane–oxazoline/thiazole ligands, by replacing the N‐phosphane group with a π‐acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir‐phosphoroamidite–oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the N‐donor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N‐phosphane by a phosphoroamidite group in the bicyclic N‐phosphane–oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated.
On Copper(I) Fluorides, the Cuprophilic Interaction, the Preparation of Copper Nitride at Room Temperature, and the Formation Mechanism at Elevated Temperatures
Authors: Woidy Patrick , Karttunen Antti J. , Widenmeyer Marc , Niewa Rainer , Kraus Florian
Published: January 2015

Our attempts to synthesize the hitherto unknown binary copper(I) fluoride have led to first successes and a serendipitious result: By conproportionation of elemental copper and copper(II) fluoride in anhydrous liquid ammonia, two copper(I) fluorides were obtained as simple NH3 complexes. One of them presents an example of ligand‐unsupported “cuprophilic” interactions in an infinite [Cu2(NH3)4]2+ chain with alternating Cu–Cu distances. We discovered that both copper(I) fluorides can easily be converted into Cu3N at room temperature, just by applying a vacuum. Additionally, we investigated the formation mechanism of the classical synthesis route of Cu3N that starts with CuF2 and flowing NH3 in the temperature range between ambient and 290 °C by means of thermal analysis and in situ neutron diffraction. The reaction proceeds at elevated temperatures through the formation of a blue and amorphous ammoniate Cu(NH3)2F2, the reformation of CuF2, and finally the redox reaction to form Cu3N.