bluuebunny/crossref_metadata_2025 huggingface dataset:
Size-resolved cloud condensation nuclei (CCN) activity and closure analysis at the HKUST Supersite in Hong Kong
Authors: Meng J. W. , Yeung M. C. , Li Y. J. , Lee B. Y. L. , Chan C. K.
Published: September 2014

Abstract. The cloud condensation nuclei (CCN) properties of atmospheric aerosols were measured on 1–30 May 2011 at the HKUST (Hong Kong University of Science and Technology) Supersite, a coastal site in Hong Kong. Size-resolved CCN activation curves, the ratio of number concentration of CCN (NCCN) to aerosol concentration (NCN) as a function of particle size, were obtained at supersaturation (SS) = 0.15, 0.35, 0.50, and 0.70% using a DMT (Droplet Measurement Technologies) CCN counter (CCNc) and a TSI scanning mobility particle sizer (SMPS). The mean bulk size-integrated NCCN ranged from ~500 cm−3 at SS = 0.15% to ~2100 cm−3 at SS = 0.70%, and the mean bulk NCCN / NCN ratio ranged from 0.16 at SS = 0.15% to 0.65 at SS = 0.70%. The average critical mobility diameters (D50) at SS = 0.15, 0.35, 0.50, and 0.70% were 116, 67, 56, and 46 nm, respectively. The corresponding average hygroscopic parameters (κCCN) were 0.39, 0.36, 0.31, and 0.28. The decrease in κCCN can be attributed to the increase in organic to inorganic volume ratio as particle size decreases, as measured by an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The κCCN correlates reasonably well with κAMS_SR based on size-resolved AMS measurements: κAMS_SR = κorg × forg + κinorg × finorg, where forg and finorg are the organic and inorganic volume fractions, respectively, κorg = 0.1 and κinorg = 0.6, with a R2 of 0.51. In closure analysis, NCCN was estimated by integrating the measured size-resolved NCN for particles larger than D50 derived from κ assuming internal mixing state. Estimates using κAMS_SR show that the measured and predicted NCCN were generally within 10% of each other at all four SS. The deviation increased to 26% when κAMS was calculated from bulk PM1 AMS measurements of particles because PM1 was dominated by particles of 200 to 500 nm in diameter, which had a larger inorganic fraction than those of D50 (particle diameter < 200 nm). A constant κ = 0.33 (the average value of κAMS_SR over the course of campaign) was found to give an NCCN prediction within 12% of the actual measured values. We also compared NCCN estimates based on the measured average D50 and the average size-resolved CCN activation ratio to examine the relative importance of hygroscopicity and mixing state. NCCN appears to be relatively more sensitive to the mixing state and hygroscopicity at a high SS = 0.70% and a low SS = 0.15%, respectively.
Soil organic matter dynamics under different land use in grasslands in Inner Mongolia (northern China)
Authors: Zhao L. , Wu W. , Xu X. , Xu Y.
Published: September 2014

Abstract. We examined bulk soil properties and molecular biomarker distributions in surface soils from Inner Mongolian grasslands in order to understand the responses of soil organic matter to different land use. A total of 16 soils were collected from severely degraded grassland by overgrazing (DG), native grassland without apparent anthropogenic disturbance (NG), groundwater-sustaining grassland (GG) and restored grassland from previous potato cropland (RG). Compared to NG, soil organic carbon content was lower by 50% in DG, but higher by six-fold in GG and one-fold in RG. The δ13C values of soil organic carbon were –24.2 ± 0.6‰ in DG, –24.9 ± 0.6‰ in NG, –25.1 ± 0.1‰ in RG and –26.2 ± 0.6‰ in GG, reflecting different degradation degrees of soil organic matter or different water use efficiencies. The soils in DG contained the lowest abundance of aliphatic lipids (n-alkanes, n-alkanols, n-alkanoic acids, ω-hydroxylalkanoic acids and α-hydroxyalkanoic acids) and lignin-phenols, suggesting selective removal of these biochemically recalcitrant biomarkers with grassland degradation by microbial respiration or wind erosion. Compared to NG, the soils in GG and RG increased ω-hydroxylalkanoic acids by 60–70%, a biomarker for suberin from roots, and increased α-hydroxylalkanoic acids by 10–20%, a biomarker for both cutin and suberin. Our results demonstrate that the groundwater supply and cultivation–restoration practices in Inner Mongolian grasslands not only enhance soil organic carbon sequestration, but also change the proportions of shoot- versus root-derived carbon in soils. This finding has important implications for the global carbon cycle since root-derived aliphatic carbon has a longer residence time than the aboveground tissue-derived carbon in soils.
Prevalencia de Diabetes Mellitus y factores de riesgo en mayores de 20 años de las cabeceras departamentales de Nicaragua
Authors: Aráuz Lazo Irma , Delgado Aráuz Yaraceli , Delgado Téllez Edgar
Published: September 2014

El estudio se centró en determinar la prevalencia de Diabetes Mellitus en mayores de 20 años en el área urbana de Nicaragua. Se seleccionó la población mayor de 20 años, utilizando la proyección del censo de 2010 en las cabeceras del norte, centro y pacífico de Nicaragua. La Costa Caribe fue excluida por problemas de factibilidad. Las cabeceras seleccionadas fueron escogidas al azar, estratificando los sectores de cada cabecera para la selección de la población, la que una vez definido los lugares los participantes fueron seleccionados al azar usando el método de lotería. El cálculo del tamaño de la muestra fue hecho usando el Programa Epidemiológico EPIINFO versión 6.04, usando una frecuencia de 0.5, un máximo error permisible de 3% y un intervalo de confianza del 95%, siendo multiplicado el total muestreado por dos para evitar el error por el efecto de diseño. Al final se entrevistaron un total de 3150 encuestas a los que se les preguntó por datos generales, datos sobre factores de riesgo de Diabetes Mellitus y una medición de variables biológicos (Presión arterial, frecuencia cardiaca, pulso, peso, talla, cintura, cadera y la medición de la glicemia ya fuese en ayunas o glicemia casual) Los resultados evidencian la prevalencia fue de 9.5%; 6.1% resultaron ser prediabéticos y 84.4% al momento de hacer la encuesta no padecían de la enfermedad. Hubo un predominio de Diabetes en el sexo masculino con 12.9% y en el sexo femenino se encontró una prevalencia de 7.4%. Por grupos etáreos predominó en la mayoría de 40 años. De los 300 diabéticos encontrados en el estudio, 171 (57%) sabían que eran diabéticos y 129 (43%) desconocían que padecían de la enfermedad. Los principales factores de riesgo encontrados fueron: la edad mayor de 45 años (OR:5.5; IC95%: 4.2-7.2), para las mujeres la 95% historia de Diabetes gestacional (OR:4.5; IC95%: 1.7-11.7), hipertensión arterial (OR:4.0; IC95%: 3.1-5.1), sedentarismo (OR:3.1; IC95%: 2.4-4.1), obesidad (OR:2.7; IC95%: 2.0-3.7), e historia familiar de Diabetes (OR:2.0; IC95%: 1.6-2.6). En conclusión, la Diabetes Mellitus constituye un problema importante para la salud pública para la población nicaragüense y que en países con pocos recursos la prevención debe ir orientada a cambiar factores de riesgo modificables como sedentarismo y obesidad en la población y la promoción de estilos de vida saludables. DOI: http://dx.doi.org/10.5377/universitas.v5i1.1476 UNIVERSITAS (León): Revista Científica de la UNAN León Vol.5(1) 2014, pp 1-10
Evaluación de la homogeneidad de la muestra y estudio intralaboratorio de la precisión intermedia en la determinación de aflatoxinas en maní de exportación
Authors: Delgado Gustavo
Published: September 2014

En el presente trabajo se ha aplicado el diseño experimental factorial piramidal para evaluar la homogeneidad en el contenido de aflatoxinas en muestras de maní de exportación, utilizando como técnica de medición analítica la cromatografía líquida de alto desempeño con detector de fluorescencia (HPLC-FLD). Este diseño permitió evaluar la precisión del método de ensayo y se comparó con valores de referencia del Codex Alimentario. En primer lugar, la muestra del lote se dividió en 3 submuestras, las cuales fueron tratadas independientemente, tomando en cuenta el instrumento de medición, el analista, y diferentes porciones de ensayo. Al aplicar el análisis de varianza de 4 factores, se demostró que el contenido de aflatoxinas en el lote de maní en estudio está distribuido en forma heterogénea. A cada submuestra, se aplicó un diseño ANOVA 3F y se evaluó la precisión del método mediante el cálculo de las desviaciones estándares relativas de repetibilidad (RSDr) y de reproducibilidad intralaboratorio (RSDLab), encontrándose que, a pesar de algunas diferencias en el análisis de varianza, los valores de RSD son menores que los establecidos en el Codex. Esto significa que el método de ensayo utilizado cumple con la conformidad de los parámetros de precisión establecidos en normas internacionales. DOI: http://dx.doi.org/10.5377/universitas.v5i1.1477UNIVERSITAS (León): Revista Científica de la UNAN León Vol.5(1) 2014, pp 11-25
Factores de riesgo/protección y prevalencias del consumo de sustancias psicoactivas en adolescentes de enseñanza media del “Instituto Nacional de Occidente” León, Junio-mayo
Authors: Flores Dolmus Lenin A , Medina Sandino Claudia
Published: September 2014

La investigación se centró en determinar edad de inicio, factores de riesgo/protección, prevalencia e incidencia del consumo de sustancias psicoactivas lícitas e ilícitas. Se utilizó la metodología de la CICAD-OEA-SIDUC (sistema de vigilancia contra las drogas en el hemisferio) empleada en estudios nacionales, de Latinoamérica y el Caribe. La presente tesis contiene un enfoque clínico epidemiológico en la salud pública basada en un estudio descriptivo de corte transversal con una población constituida por 1,116 estudiantes adolescentes y una muestra representativa de 286 escolares de ambos sexos, se aplicó el cuestionario estandarizado SIDUC con indicadores predeterminados para medir tasas de prevalencia y patrones de consumo. Resultados y conclusiones evidencian que entre las drogas licitas el alcohol posee las mayores prevalencias entre los estudiantes: consumo experimental 45.5%, reciente 28.3% y actual 19.9%, seguido por el tabaco, entre las drogas ilícitas la mariguana posee las mayores prevalencias: consumo experimental 13.6%, reciente 6.3% y actual 2.8%, seguida por la cocaína. Las prevalencias indican mayores porcentajes de consumo entre los varones, la jornada vespertina, el décimo grado y las edades entre 15-17 años. Son factores de riesgo la calle y eventos sociales, las edades de inicio cada vez más tempranas, con una edad media de 11.6 años y el entorno de pares. Son factores protectores de los estudiantes las expectativas futuras positivas y la percepción de “gran riesgo” hacia el consumo de drogas.DOI: http://dx.doi.org/10.5377/universitas.v5i1.1485 UNIVERSITAS (León): Revista Científica de la UNAN León Vol.5(1) 2014, pp 126-145
Scratch it out! Enhancing Geometrical Understanding
Authors: Smith Carmen Petrick , Neumann Maureen D.
Published: September 2014

This article presents the implementation of an activity that investigates geometrical transformations through designing and physically acting out coding programs based on the free software Scratch. The activity helped students integrate mathematics and computer programming content so to better understand geometrical content. Authors of iSTEM: Integrating Science, Technology, and Engineering with Mathematics articles share ideas and activities that stimulate student interest in the integrated fields of science, technology, engineering, and mathematics (STEM) in K—grade 6 classrooms.
Foreign Direct Investment, Institutions and Economic Growth: Evidence from the MENA Region
Authors: Brahim Mariem , Rachdi Houssem
Published: September 2014

Few scientific papers treat the role of institutions on the relationship between foreign direct investment (hereafter FDI) and economic growth. In the existing literature, the FDI effects on growth are not easy to understand. Mixed findings, both theoretical and empirical, have been provided on this issue by the academic research. The first contribution of this study is an analysis of how institutions quality affects FDI-growth nexus. The second contribution is the use of the Panel Smooth Transition Regression (PSTR) modeling because the nexus between FDI and economic growth is nonlinear and depends on specific national factors especially institutions quality. This method helps to account for a change of regime in the effects of FDI on economic growth. The major finding of this study is that the effect of FDI on economic growth is conditional to the development of institutions in MENA countries. Empirically, on a sample of 19 MENA countries over the period 1984-2011, we found that only countries with good institutions can exploit the advantages of FDI on growth.
Le Droit et la rénovation de la Basse-Ville d’Ottawa : les balbutiements d’un journalisme engagé dans le dossier de l’aménagement urbain
Authors: Gilbert Anne , Benali Kenza , Ramirez Caroline
Published: September 2014

Lorsque la municipalité d’Ottawa approuve en 1966 le plus vaste projet de rénovation urbaine jamais entrepris au Canada, à savoir celui de l’est de la Basse-Ville, le principal quartier francophone de la capitale, le journal Le Droit affiche un enthousiasme débordant. Il n’hésite pas à soutenir cette initiative, née d’une volonté de moderniser un centre-ville marqué par l’insalubrité. Il faudra attendre près d’une dizaine d’années, lorsqu’une grande partie du plan aura été réalisée, pour assister à un revirement dans la position du journal, qui constate alors les effets dévastateurs de la rénovation urbaine sur les conditions de vie des habitants. Les prises de position initiales des journalistes ont été influencées par le manque d’expertise des informateurs issus de la communauté locale. Les spécificités du journalisme de proximité desservant une population minoritaire ont ainsi joué un rôle dans la couverture du Droit. Telle est la thèse que nous explorons ici, à travers l’analyse de contenu du journal sur une période de près de 15 ans.
La Route des Vins et l’émergence d’un tourisme viticole en Bourgogne dans l’entre-deux-guerres
Authors: Jacquet Olivier , Laferté Gilles
Published: September 2014

À la fin du XIXesiècle, les guides excluent totalement la gastronomie et la vigne des visites qu’ils proposent aux touristes de passage en Bourgogne. Seuls les sites naturels et les monuments historiques attirent l’attention des voyageurs. La gastronomie et le vin sont alors perçus et vendus comme des produits de luxe aristocratiques et internationaux – c’est-à-dire territorialement désincarnés. Le poids du négoce et sa liberté en termes de vinification (capacité d’assemblages de vins d’origines géographiques différentes) conditionnent amplement cette réalité. À la fin des années 1930, la transformation des normes de production et de commercialisation des vins en faveur d’un système d’appellations d’origine, combinée à la réinvention culturelle des folklores régionaux et aux volontés républicaines de valoriser les petites patries au sein de la grande patrie française, vont bouleverser les représentations régionales. En s’appropriant les concepts folkloristes républicains, les acteurs du marché des vins fins bourguignons vont ainsi réinventer l’univers de sens du produit. Ces initiatives aboutissent à la création d’une nouvelle réalité touristique pour la Bourgogne, désormais visitée pour ses vignes et ses vins, réalité qui se concrétise en 1937 par la création, en Bourgogne, de la toute première route touristique vitivinicole en France.
Holocaust roadscapes: Retracing the "death marches" in contemporary Europe
Authors: Cole Tim
Published: September 2014

During the final year of the war, mass evacuations westwards from concentration camps on foot brought the European road network into the orbit of Holocaust landscapes. The routes of these so-called “death marches” that criss-crossed Europe have been followed by a wide variety of pilgrims, ranging from Holocaust survivors retracing former journeys they made half a century before (oftentimes accompanied by family members, and in some cases, documentary filmmakers), through organized groups of Jews and Christians, to visual artists. While motivated by very different concerns, all share assumptions that the encounter with place – an authentic site of wartime atrocity – shrinks time, merging past and present (and future). Such notions of the possibility of direct access to the past are heightened by the haptic and embodied experiences of place that are central to walking. The individuals and groups I examine aspire, quite literally, to follow in the footsteps of the victims, walking on the very same ground they walked. While these attempts at shrinking or “fixing” time have been seen variously as more or less successful, all share an assumption of the potential intersections of past, present and future in these seemingly most ordinary of memoryscapes.
Maintien de la paix. Apports et limites de l’action diplomatique sud-africaine
Authors: Dieng Moda
Published: September 2014

Ce document étudie les apports et les limites de l’Afrique du Sud en matière de maintien de la paix. L’Afrique du Sud, première puissance économique et militaire africaine et pays émergent, joue un rôle diplomatique important en Afrique, le continent qui accueille le plus grand nombre des actions de maintien de la paix. Ses capacités et son leadership lui ont permis de remorquer des processus de médiation, de mobiliser des intervenants extérieurs, de se mettre en première ligne dans certaines opérations de maintien de la paix, renforçant ainsi sa crédibilité dans la gestion des conflits. Toutefois, depuis quelque temps, l’engagement de l’Afrique du Sud, qui présentait déjà beaucoup de faiblesses, tant en termes de capacités que de leadership conforme à sa réputation et à son statut, semble connaître une perte de vitesse. En revanche, on note une montée en puissance d’uneRealpolitik, qui suscite beaucoup de critiques.
Multimedia-Aided Instruction in Teaching Grade Four Science and Health: Its Effect on Pupils' Performance and Attitude Towards Multimedia Use in the Classroom
Authors: Galope Virlen O.
Published: September 2014

This study is focused on the effects of multimedia aided instructions in Grade 4 Science and health pupils' performance and attitude towards multimedia. Specifically this study sought to explore the multimedia aided instruction on the learning environment of the grade four pupils' performance in science and health. Two intact classes in grade 4 were exposed to multimedia aided instructions. The difference in gain scores produced by integrating multimedia in Science and Health 4 classes and those produced by conventional method of teaching was investigated in this quasi experimental research. Results indicated that using the multimedia in the classes produced significant improvement in the performance of the pupils in Science and Health, but not in the other, which is congruent with most other results for this strategy of teaching found in the literature. Follow-up survey of attitudes of 86 pupils towards the use of multimedia in the classroom provided additional evidence for its positive effect in the teaching learning process. The pupils' attitudes towards their class were positive about the potential for multimedia and enthusiastic about what this would mean in learning Science and Health. Utilizing multimedia seemed to affect the teachers' personal and professional growth. Teachers expect to develop their technological skills and knowledge to use multimedia in their classrooms. Pedagogical issues challenge the teachers' approaches in the teaching and learning.
Job Search Time and Self-Perceptions of Curriculum Impact among Technology and Livelihood Majors in Mindanao University of Science and Technology
Authors: Putis Lilia Q.
Published: September 2014

Higher education is more than just a simple production line for job-ready graduates as it is the role of HEIs to provide relevant technical and vocational trainings on top of a well-planned curriculum, solid teaching force, and sustainable instructional infrastructures. Pursuant to RA 7722, this graduate tracer study of BSEd-TLE alumni from SY 2008-2009 to SY 2011-2012 measures job search time and self-perceptions of curriculum impact on self-esteem, financial assistance extended, and financial capability. This descriptive research (n=41) examined these variables as influenced by personal and educational profile. Waiting time for the first job with a mean of 6.44 months (between one to 18 months) is seem to be unaffected by both personal and educational profile. On average, the respondents expressed optimism on the effect the TLE curriculum on their self-esteem. Evidence suggests very high ratings in competence, confidence, commitment, compassion, faith, hope, honesty, diligence, hard work, punctuality, self-discipline, and zeal for service. Inferential statistics shows only grade point average had a significant influence on self-perceptions of self-esteem effects. Furthermore, TLE majors explained they are moderately able to support basic, educational, and shelter needs. The results warrant further analysis and follow-up so necessary revisions to the curriculum may be in order.
Una mirada al turismo residencial en la Isla de Cozumel, México
Authors: Palafox-Muñoz Alejandro , Dzib Basto Alejandra Del Rosario , Kauil-Fernández Emmanuel
Published: September 2014

El destino turístico de Cozumel ha experimentado en los últimos años una serie de cambios notorios debido a los diversos tipos de turismo que se desarrollan en la localidad. El turismo de cruceros y el de buceo son los segmentos que se han promovido a lo largo del tiempo y en los últimos años ha comenzado un impulso al turismo deportivo. Dichos segmentos de mercado han sido promotores del turismo residencial en la ínsula, el cual no ha sido tema de análisis académico, por ello, este documento pretende realizar una aproximación al estudio del tema, ya que la revisión literaria afirma que este tipo de turismo ha causado fuertes impactos negativos de índole ambiental, económico y social para la comunidad receptora. Se destacan varios actores sociales inmersos en el análisis, tales como la población residente, los nuevos residentes (principalmente extranjeros), el gobierno y las empresas inmobiliarias. Por medio de la aplicación de un instrumento para la recopilación de datos y su aplicación in situ, se estableció el panorama general del desarrollo del turismo residencial en Cozumel, pero la complejidad del tema y la diversidad de variables para su análisis requieren de un esfuerzo mayor y multidisciplinario, por lo que el presente artículo prioriza su atención en tres aspectos: a) la motivación de los extranjeros por su cambio de residencia; b) el daño al litoral por las construcciones; y c) la división de las formas de vida entre el habitante local y el nuevo residente.
Potential drivers of sinking particle's size spectra and vertical flux of particulate organic carbon (POC): Turbulence, phytoplankton, and zooplankton
Authors: Wiedmann Ingrid , Reigstad Marit , Sundfjord Arild , Basedow Sünnje
Published: September 2014

Phytoplankton spring blooms in temperate and high‐latitude shelf seas are commonly associated with an enhanced particulate organic carbon (POC) export of aggregates from the euphotic zone. In contrast, a postbloom situation is usually linked to a predominant POC retention, where small cells (<10 μm) and strong grazing pressure prevail. This study aimed to examine impacts of turbulence, phytoplankton, bloom stage, and zooplankton abundance on the sinking particles' size spectra and POC flux to improve the understanding of the downward flux mechanisms in the upper 100 m. We deployed sediment traps, partly modified with gel jars, at four depths along a stratification and phytoplankton bloom gradient in the Barents Sea, an Arctic shelf sea. The highest POC export (60 m: 923 mg C m−2 d−1) was found in deep‐mixed, postbloom Atlantic influenced waters, despite the high grazer abundance (12,000 individuals m−3). Particle size spectra indicated that this flux was dominated by particles of 0.05–1.00 mm equivalent spherical diameter (ESDimage) with a POC:volume ratio matching copepod fecal pellets. Large particles (0.5–2.8 mm ESDimage) dominated the flux at a stratified, late peak bloom station in Arctic Waters and a stratified, late bloom situation at the Polar Front, but with lower POC:volume ratio and POC flux (60 m: <823 mg C m−2 d−1). Accordingly, a high POC flux at the base of the euphotic zone is not necessarily driven by large phytoplankton aggregates, but can also occur during a postbloom situation in form of small fecal pellet fragments with high POC content.
A ventilation‐based framework to explain the regeneration‐scavenging balance of iron in the ocean
Authors: Tagliabue Alessandro , Williams Richard G. , Rogan Nicholas , Achterberg Eric P. , Boyd Philip W.
Published: September 2014

Our understanding of the processes driving the patterns of dissolved iron (DFe) in the ocean interior, either in observations or models, is complicated by the combined influences of subduction from the surface mixed layer, notable subsurface sources, regeneration, and scavenging loss. We describe a ventilation‐based framework to quantify these processes in a global ocean biogeochemical model including diagnostics along potential density surfaces. There is a prevailing control of subsurface DFe by the subduction of surface DFe as preformed DFe augmented by benthic sources of DFe from hydrothermal activity and sediments. Unlike phosphate, there is often a first‐order balance with a near cancelation between regeneration and scavenging with the remaining “net regeneration” controlled by the ventilation of surface excesses in Fe‐binding ligands. This DFe framework provides a more stringent test of how the total DFe distribution is mechanistically controlled within a model and may be subsequently used to interpret observed DFe distributions.
Recent Progress on Magnetorheological Solids: Materials, Fabrication, Testing, and Applications
Authors: Ubaidillah  , Sutrisno Joko , Purwanto Agus , Mazlan Saiful Amri
Published: September 2014

Magnetorheological (MR) materials are classified as smart materials due to their responsiveness to external magnetic stimuli. Intensive research on MR materials has led to broad applications in several potential fields. A solid carrier matrix state called MR elastomer with its exceptional magnetic responsive feature is obtained by merging magnetizable particles within an elastomeric polymer. This integration results in outstanding characteristics on the rheological performances. Special prominence is given to the understanding of the base materials and fabrication as well as the functional behavior through various characterization methods. Broad applications of MREs are also explored to provide a profound market picture and to motivate researchers to develop novel technology.
Spark Plasma Sintering and Characterization of Graphene Platelet/Ceramic Composites
Authors: Jiang Kyle , Li Jiran , Liu Jian
Published: September 2014

This paper reports a study on sintering and characterization of graphene platelet (GPL)‐reinforced ceramic composites. Alumina (Al2O3) and zirconia (ZrO2) toughened Al2O3 (ZTA) composites reinforced with GPLs are fabricated, respectively, using spark plasma sintering. The microstructures and mechanical properties of the sintered samples are investigated. It is found that the addition of GPLs hinders the growth of the ceramic matrix grains and help form homogenous microstructures of the ceramic matrices. Agglomeration of GPLs occurs during the fabrication process and formation of GPL aggregates is impeded when ceramic powders of smaller particle size and a shorter milling process are used. Fracture toughness of the ceramic matrices is significantly improved by introducing GPLs. Approximately, a 26.4% and a 29% improvements in fracture toughness are achieved for GPL/Al2O3 and GPL/ZTA composites, respectively. The main toughening mechanisms induced by GPLs are pull‐out and crack bridging.
Recent Advances in Optically Active Polymer‐Based Nanowires and Nanotubes
Authors: Garreau Alexandre , Duvail Jean‐Luc
Published: September 2014

There is tremendous interest in one‐dimensional nanostructures, since they permit enhanced properties as well as new paradigms for electronic, optical, optoelectronic, and photonic devices. Besides inorganic systems, nanowires (NWs) and nanotubes (NTs) containing an optically active polymer are now being intensively investigated. This article reviews recent developments in the various preparation methods and in the optically related properties of polymer‐based NWs and NTs. The case of both conjugated polymers (CPs) and polymers containing photo‐active species is described herein. The latest developments in synthesis methods allow the design of NWs and NTs with improved features or with more complex architectures, including coaxial, (multi‐)segmented, hybrid, and composite systems. Consequently, it is possible to control and to tune their properties, as well as to reach new behaviors and multifunctionality. After a review of the fabrication methods, this paper focuses on the optical and optoelectronic features of polymer‐based NWs and NTs: electrochromism, photoluminescence and color control, electroluminescence, waveguiding and nanolasing effects, photoconductivity and photovoltaic devices, and plasmon‐coupled systems. The emphasis is on the emerging strategies for understanding and controlling the behavior of charges, excitons and photons, as required for developing the next generation of devices.
Definition of 5q11.2 microdeletion syndrome reveals overlap with CHARGE syndrome and 22q11 deletion syndrome phenotypes
Authors: Snijders Blok Charlotte , Corsten‐Janssen Nicole , FitzPatrick David R. , Romano Corrado , Fichera Marco , Vitello Girolamo Aurelio , Willemsen Marjolein H. , Schoots Jeroen , Pfundt Rolph , van Ravenswaaij‐Arts Conny M.A. , Hoefsloot Lies , Kleefstra Tjitske
Published: September 2014

Microdeletions of the 5q11.2 region are rare; in literature only two patients with a deletion in this region have been reported so far. In this study, we describe four additional patients and further define this new 5q11.2 microdeletion syndrome. A comparison of the features observed in all six patients with overlapping 5q11.2 deletions showed a phenotypic spectrum that overlaps with CHARGE syndrome and 22q11.2 deletion syndrome including choanal atresia, developmental delay, heart defects, external ear abnormalities, and short stature. No colobomas or abnormalities of semicircular canals and olfactory nerves were reported. Two male patients had genital abnormalities. We estimated a 2.0 Mb (53.0–55.0 Mb) Shortest Region of Overlap (SRO) for the main clinical characteristics of the syndrome. This region contains nine genes and two non‐coding microRNAs. In this region DHX29 serves as the candidate gene as it encodes an ATP‐dependent RNA‐helicase that is involved in the initiation of RNA translation. Screening a small cohort of 14 patients who presented the main features, however, did not reveal any pathogenic abnormalities of DHX29. © 2014 Wiley Periodicals, Inc.
A five generation family with a novel mutation in FOXC2 and lymphedema worsening to hydrops in the youngest generation
Authors: Sargent Carole , Bauer Julien , Khalil Muhamed , Filmore Parker , Bernas Michael , Witte Marlys , Pearson M. Peggy , Erickson Robert P
Published: September 2014

We describe a five generation family with dominantly inherited lymphedema, but no distichiasis, in which 3/3 affected offspring in the fifth generation have died of fetal hydrops and related birth defects. Mutational analysis disclosed a novel mutation in FOXC2 (R121C) in affected members. We searched for possible genetic influences on the greater severity of lymphedema (hydrops) in the fifth generation. Karyotypes disclosed an extra band in Xp in one affected fetus, but this was also found in the mother. Copy number variation (CNV) studies on four members of the pedigree (mother of the three severely affected fetuses/infants; one severely affected; a full, and a half, unaffected sibs) did not detect the source of the Xp band or a possible influence on the severe phenotype. However, use of SNP arrays did allow identification of the portion of the maternal proximal Xp shared by a hydrops‐affected daughter and son which was not shared by an unaffected daughter from the same sibship. © 2014 Wiley Periodicals, Inc.
Metallkatalysierte desalkoxylierende CAr‐C‐Kreuzkupplung – Austausch aromatischer Methoxygruppen von Arylethern unter Verwendung eines funktionalisierten Nukleophils
Authors: Leiendecker Matthias , Hsiao Chien‐Chi , Guo Lin , Alandini Nurtalya , Rueping Magnus
Published: September 2014

Der direkte Austausch aromatischer Methoxygruppen mit einem aktivierten Kohlenstoffatom würde neue Wege für gezielte und diversitätsorientierte Synthesen bahnen. Wir zeigen hier, dass solche Reaktionen in einem Schritt mit einem difunktionellen Nukleophil und einem CAr‐OMe‐bindungsspaltenden Katalysator ablaufen können. Die gebildeten Produkte sind stabil, α‐CH‐aktiv und für diverse weitere Modifikationen geeignet.
RNA Interference Controlled by Light of Variable Wavelength
Authors: Meyer Andreas , Mokhir Andriy
Published: September 2014

Known molecular, “caged” siRNAs are activated by UV light. Since the light of this type is toxic to cells, the uncaging can cause undesired side effects. A modular, molecular system for designing siRNAs is reported, which can be activated by non‐toxic light in live cells. For example, siRNAs responsive to green and red light are described. The uncaging is mediated by 1O2 photogenerated on a photosensitizer, which is attached to the 3′‐terminus of the lagging strand. The 5′‐terminus of the guide strand is alkylated (“caged”) with a 9‐anthracenyl residue. The latter fragment reacts with the 1O2 with formation of the free (uncaged) 5′‐OH terminus. Simultaneously with the uncaging the photosensitizer is bleached and no more 1O2 is generated after this process is completed. The photoactivation of the siRNAs described here is not toxic to cells.
Bildung und Umlagerung von Homoserin‐Depsipeptiden und ‐proteinen durch α‐Ketosäure‐Hydroxylamin‐Ligation mit 5‐Oxaprolin
Authors: Wucherpfennig Thomas G. , Rohrbacher Florian , Pattabiraman Vijaya R. , Bode Jeffrey W.
Published: September 2014

Die Hauptprodukte der chemischen Ligation von α‐Ketosäuren und 5‐Oxaprolin sind Ester und nicht – wie zuvor berichtet – Amide. Durch die schnell ablaufende Umlagerung in basischen Puffern lässt sich das Depsipeptidprodukt in das Amid überführen. Die Esterbildung ermöglicht Rückschlüsse auf den möglichen Mechanismus von Typ‐II‐KAHA‐Ligationen und eröffnet einen Weg zur chemischen Synthese von Depsiproteinen.
Catalytic Wittig Reactions of Semi‐ and Nonstabilized Ylides Enabled by Ylide Tuning
Authors: Coyle Emma E. , Doonan Bryan J. , Holohan Andrew J. , Walsh Killian A. , Lavigne Florie , Krenske Elizabeth H. , O'Brien Christopher J.
Published: September 2014

The first examples of catalytic Wittig reactions with semistabilized and nonstabilized ylides are reported. These reactions were enabled by utilization of a masked base, sodiumtert‐butyl carbonate, and/or ylide tuning. The acidity of the ylide‐forming proton was tuned by varying the electron density at the phosphorus center in the precatalyst, thus facilitating the use of relatively mild bases. Steric modification of the precatalyst structure resulted in significant enhancement ofE selectivity up to >95:5,E/Z.
Photo‐Organocatalysis of Atom‐Transfer Radical Additions to Alkenes
Authors: Arceo Elena , Montroni Elisa , Melchiorre Paolo
Published: September 2014

We have found that an organic molecule as simple as p‐anisaldehyde efficiently catalyzes the intermolecular atom‐transfer radical addition (ATRA) of a variety of haloalkanes onto olefins, one of the fundamental carbon–carbon bond‐forming transformations in organic chemistry. The reaction requires exceptionally mild reaction conditions to proceed, as it occurs at ambient temperature and under illumination by a readily available fluorescent light bulb. Initial investigations support a mechanism whereby the aldehydic catalyst photochemically generates the reactive radical species by sensitization of the organic halides by an energy‐transfer pathway.
Ein Metall‐organisches Netzwerk auf Basis von Cu‐Adatom‐ Trimeren
Authors: Bebensee Fabian , Svane Katrine , Bombis Christian , Masini Federico , Klyatskaya Svetlana , Besenbacher Flemming , Ruben Mario , Hammer Bjørk , Linderoth Trolle R.
Published: September 2014

Mittels Koadsorption von Metallatomen und organischen Liganden hergestellte Koordinationsnetzwerke haben interessante Eigenschaften, z. B. in der Katalyse oder für die Datenspeicherung. Bisher basierten solche Oberflächen‐Netzwerke auf Koordination an einzelnen Metallatomen. Hier beschreiben wir hingegen die Bildung eines neuartigen Metall‐organischen Netzwerkes, das auf Kupfertrimeren als Noden basiert. Dieses Netzwerk entsteht nach dem Aufdampfen und anschließendem Heizen von Tetrahydroxybenzol (THB) auf Cu(111) im Ultrahochvakuum. Mittels STM, XPS und DFT‐Rechnungen konnte gezeigt werden, dass bei einer Temperatur von 440 K alle vier Hydroxygruppen des THB dehydriert werden. Der dabei entstehende, hochreaktive Ligand bindet anschließend an Cu‐Trimere, die in hochaufgelösten STM‐Aufnahmen sichtbar sind. Mit den gleichmäßig angeordneten und monodispersen Cu‐Trimeren stellt das hier vorgestellte Netzwerk ein zweidimensionales Analogon zu Metall‐organischen Gerüsten dar, die in der Regel ebenfalls komplexere Noden als einzelne Metallatome aufweisen.
Aktivatoren des molekularen Chaperons Hsp90 erleichtern geschwindigkeitsbestimmende Konformationsänderungen
Authors: Zierer Bettina K. , Weiwad Matthias , Rübbelke Martin , Freiburger Lee , Fischer Gunter , Lorenz Oliver R. , Sattler Michael , Richter Klaus , Buchner Johannes
Published: September 2014

Der Reaktionszyklus des molekularen Chaperons Hsp90 ist durch ATP‐getriebene Konformationsänderungen charakterisiert, die der ATP‐Hydrolyse vorgeschaltet sind. Es gibt bereits niedermolekulare Inhibitoren von Hsp90, die mit der ATP‐Bindung konkurrieren. Wir fragten uns, ob Verbindungen existieren, die den konformationellen Zyklus beschleunigen können. In einem FRET‐basierten Screen, der Konformationsänderungen in Hsp90 detektiert, identifizierten wir zwei Verbindungen und analysierten ihre Wirkungsweise. Wir können zeigen, dass die intrinsische Inhibition von Hsp90, welche konformationelle Umlagerungen verhindert, durch diese Substanzen überwunden wird. Diese Wirkungsweise ähnelt der des Cochaperons Aha1 von Hsp90, das die ATPase‐Aktivität beschleunigt. Während beide Verbindungen Konformationsänderungen beeinflussen, so steuern sie jeweils verschiedene Aspekte der Strukturübergänge. Zudem unterscheiden sich ihre durch NMR‐Spektroskopie bestimmten Bindestellen. Unsere Studie zeigt, dass kleine Moleküle in der Lage sind, spezifische geschwindigkeitsbestimmende Übergänge in Hsp90 in ähnlicher Weise zu beschleunigen wie dies durch Protein‐Cofaktoren geschieht.
Superbenzol‐Porphyrin‐Konjugate
Authors: Lungerich Dominik , Hitzenberger Jakob F. , Marcia Mario , Hampel Frank , Drewello Thomas , Jux Norbert
Published: September 2014

Ein nichtmetalliertes Porphyrin mit zwei trans‐ständigen Hexabenzocoronen(HBC)‐Substituenten und der zugehörige Zinkkomplex wurden hergestellt. Die Verbindungen wurden ausführlich untersucht, und es zeigte sich, dass sie in der Gasphase trikationische Dimere bilden. Die Röntgenstrukturanalyse des Zinkkomplexes ergab eine ausgeprägte π‐Stapelwechselwirkung, wohingegen beim nichtmetallierten Porphyrin n‐Heptan interkaliert, was die π‐Stapelung weitgehend verhindert. Die Anregung der HBC‐Substituenten führt zu einem effizienten Energietransfer zum Porphyrinkern.
Single‐Site Copper(II) Water Oxidation Electrocatalysis: Rate Enhancements with HPO42− as a Proton Acceptor at pH 8
Authors: Coggins Michael K. , Zhang Ming‐Tian , Chen Zuofeng , Song Na , Meyer Thomas J.
Published: September 2014

The complex CuII(Py3P) (1) is an electrocatalyst for water oxidation to dioxygen in H2PO4−/HPO42− buffered aqueous solutions. Controlled potential electrolysis experiments with 1 at pH 8.0 at an applied potential of 1.40 V versus the normal hydrogen electrode resulted in the formation of dioxygen (84 % Faradaic yield) through multiple catalyst turnovers with minimal catalyst deactivation. The results of an electrochemical kinetics study point to a single‐site mechanism for water oxidation catalysis with involvement of phosphate buffer anions either through atom–proton transfer in a rate‐limiting OO bond‐forming step with HPO42− as the acceptor base or by concerted electron–proton transfer with electron transfer to the electrode and proton transfer to the HPO42− base.
Theranostic Iridium(III) Complexes as One‐ and Two‐Photon Phosphorescent Trackers to Monitor Autophagic Lysosomes
Authors: He Liang , Tan Cai‐Ping , Ye Rui‐Rong , Zhao Yi‐Zhi , Liu Ya‐Hong , Zhao Qiang , Ji Liang‐Nian , Mao Zong‐Wan
Published: September 2014

During autophagy, the intracellular components are captured in autophagosomes and delivered to lysosomes for degradation and recycling. Changes in lysosomal trafficking and contents are key events in the regulation of autophagy, which has been implicated in many physiological and pathological processes. In this work, two iridium(III) complexes (LysoIr1 and LysoIr2) are developed as theranostic agents to monitor autophagic lysosomes. These complexes display lysosome‐activated phosphorescence and can specifically label lysosomes with high photostability. Simultaneously, they can induce autophagy potently without initiating an apoptosis response. We demonstrate that LysoIr2 can effectively implement two functions, namely autophagy induction and lysosomal tracking, in the visualization of autophagosomal–lysosomal fusion. More importantly, they display strong two‐photon excited fluorescence (TPEF), which is favorable for live cell imaging and in vivo applications.
MoS2 Nanoflowers with Expanded Interlayers as High‐Performance Anodes for Sodium‐Ion Batteries
Authors: Hu Zhe , Wang Lixiu , Zhang Kai , Wang Jianbin , Cheng Fangyi , Tao Zhanliang , Chen Jun
Published: September 2014

MoS2 nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high‐performance anode in Na‐ion batteries. By controlling the cut‐off voltage to the range of 0.4–3 V, an intercalation mechanism rather than a conversion reaction is taking place. The MoS2 nanoflower electrode shows high discharge capacities of 350 mAh g−1 at 0.05 A g−1, 300 mAh g−1 at 1 A g−1, and 195 mAh g−1 at 10 A g−1. An initial capacity increase with cycling is caused by peeling off MoS2 layers, which produces more active sites for Na+ storage. The stripping of MoS2 layers occurring in charge/discharge cycling contributes to the enhanced kinetics and low energy barrier for the intercalation of Na+ ions. The electrochemical reaction is mainly controlled by the capacitive process, which facilitates the high‐rate capability. Therefore, MoS2 nanoflowers with expanded interlayers hold promise for rechargeable Na‐ion batteries.
Functionalization of P4 Using a Lewis Acid Stabilized Bicyclo[1.1.0]tetraphosphabutane Anion
Authors: Borger Jaap E. , Ehlers Andreas W. , Lutz Martin , Slootweg J. Chris , Lammertsma Koop
Published: September 2014

Reacting white phosphorus (P4) with sterically encumbered aryl lithium reagents (aryl=2,6‐dimesitylphenyl or 2,4,6‐tBu3C6H2) and B(C6F5)3 gives the unique, isolable Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutane anion. Subsequent alkylation of the nucleophilic site of the RP4 anion gives access to non‐symmetrical disubstituted bicyclic tetraphosphorus compounds. This novel method enables PC bond formation in a controlled fashion using white phosphorus as starting material.
A Surface Coordination Network Based on Copper Adatom Trimers
Authors: Bebensee Fabian , Svane Katrine , Bombis Christian , Masini Federico , Klyatskaya Svetlana , Besenbacher Flemming , Ruben Mario , Hammer Bjørk , Linderoth Trolle R.
Published: September 2014

Surface coordination networks formed by co‐adsorption of metal atoms and organic ligands have interesting properties, for example regarding catalysis and data storage. Surface coordination networks studied to date have typically been based on single metal atom centers. The formation of a novel surface coordination network is now demonstrated that is based on network nodes in the form of clusters consisting of three Cu adatoms. The network forms by deposition of tetrahydroxybenzene (THB) on Cu(111) under UHV conditions. As shown from a combination of scanning tunneling microscopy, X‐ray photoelectron spectroscopy, and density functional theory calculations, all four hydroxy groups of THB dehydrogenate upon thermal activation at 440 K. This highly reactive ligand binds to Cu adatom trimers, which are resolved by high‐resolution STM. The network creates an ordered array of mono‐dispersed metal clusters constituting a two‐dimensional analogue of metal–organic frameworks.
Developing Phospha‐Stork Chemistry Induced by a Borane Lewis Acid
Authors: Hasegawa Yasuharu , Daniliuc Constantin G. , Kehr Gerald , Erker Gerhard
Published: September 2014

Bulky vinyl phosphanes undergo carbon–carbon coupling with aryl aldehydes with the help of the Lewis acid B(C6F5)3to give isolable methylene phosphonium products. Dimesityl(vinyl)phosphane undergoes a phospha‐Stork reaction with bulky enones efficiently catalyzed by B(C6F5)3to eventually yield the corresponding substituted cyclobutane products.
Artificial Accelerators of the Molecular Chaperone Hsp90 Facilitate Rate‐Limiting Conformational Transitions
Authors: Zierer Bettina K. , Weiwad Matthias , Rübbelke Martin , Freiburger Lee , Fischer Gunter , Lorenz Oliver R. , Sattler Michael , Richter Klaus , Buchner Johannes
Published: September 2014

The molecular chaperone Hsp90 undergoes an ATP‐driven cycle of conformational changes in which large structural rearrangements precede ATP hydrolysis. Well‐established small‐molecule inhibitors of Hsp90 compete with ATP‐binding. We wondered whether compounds exist that can accelerate the conformational cycle. In a FRET‐based screen reporting on conformational rearrangements in Hsp90 we identified compounds. We elucidated their mode of action and showed that they can overcome the intrinsic inhibition in Hsp90 which prevents these rearrangements. The mode of action is similar to that of the co‐chaperone Aha1 which accelerates the Hsp90 ATPase. However, while the two identified compounds influence conformational changes, they target different aspects of the structural transitions. Also, the binding site determined by NMR spectroscopy is distinct. This study demonstrates that small molecules are capable of triggering specific rate‐limiting transitions in Hsp90 by mechanisms similar to those in protein cofactors.
[2+2] Photocycloaddition of 3‐Alkenyloxy‐2‐cycloalkenones: Enantioselective Lewis Acid Catalysis and Ring Expansion
Authors: Brimioulle Richard , Bach Thorsten
Published: September 2014

By application of substoichiometric amounts (50 mol %) of a chiral Lewis acid, the intramolecular [2+2] photocycloaddition of the title compounds was achieved with high enantioselectivity (up to 94 % ee). Upon cleavage of the cyclobutane ring the resulting tricyclic products underwent ring‐expansion reactions under acidic conditions and formed anellated seven‐ or eight‐membered‐ring systems without racemization. The ring expansion could be combined with a diastereoselective reduction (triethylsilane) or allylation (allyltrimethylsilane) upon BF3 catalysis (48–87 % yield).