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Interesting Phenomenon (interesting + phenomenon)
Selected AbstractsSelf-Assembly by Ligand-Exchange ReactionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2005Dillip Kumar Chand Abstract An interesting phenomenon of ligand exchange is observed in the DMSO solution of certain self-assembled molecules generated from cis -protected PdII and organic ligands. Upon heating, assemblies such as [{Pd(en)}x(ligand)y](NO3)2x change to [Pdm(ligand)n](NO3)2m and [Pd(en)2](NO3)2. The change is also possible at room temperature when 0.5 equiv. Pd(en)(NO3)2 is added in excess to the system. The transformation is incomplete when the ligand moiety is monodentate in nature, for example in the case of 4-phenylpyridine. However, multinuclear assemblies containing nonchelating, polydentate ligands used in this study entirely favor the transformation. This process is not possible with some related PtII compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis and Characterization of Cubane-Like Cr4E4 (E = S, Se) Clusters , Molecular Structures of (,5 -RC5H4)4Cr4E4 (E = S, R = MeCO, MeO2C, EtO2C; E = Se, R = H)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2004Li-Cheng Song Abstract Treatment of the Cr,Cr singly-bonded dimers [,5 -RC5H4Cr(CO)3]2 (1, R = MeCO; 2, R = MeO2C; 3, R = EtO2C) with excess sulfur in refluxing THF gave the cubane Cr4S4 clusters (,5 -RC5H4)4Cr4S4 (4, R = MeCO; 5, R = MeO2C; 6, R = EtO2C). The cubane Cr4S4 cluster 4 reacted with excess 2,4-dinitrophenylhydrazine to produce the hydrazone derivative [,5,2,4-(NO2)2C6H3NHN=C(Me)C5H4]4Cr4S4 (7). The singly-bonded dimers of [,5 -RC5H4Cr(CO)3]2 (8, R = Me; 9, R = EtO2C), in the presence of excess selenium, reacted similarly to the linear Cr2Se complexes [,5 -RC5H4Cr(CO)2]2Se (10, R = Me; 11, R = EtO2C), which reacted with an equimolar quantity of selenium to afford the cubane Cr4Se4 clusters (,5 -RC5H4)4Cr4Se4 (12, R = Me; 13, R = EtO2C). A particularly interesting phenomenon is the cross-assembled reaction of the linear Cr2Se complexes [,5 -MeC(O)C5H4Cr(CO)2]2Se (14) and [CpCr(CO)2]2Se (15) in the presence of excess selenium in THF that gave rise to a series of cubane Cr4Se4 clusters [,5 -MeC(O)C5H4]nCp4,nCr4Se4 (16, n = 0; 17, n = 1; 18, n = 2; 19, n = 3; 20, n = 4). The possible pathway for the cross-assembled reaction is suggested. Furthermore the new clusters were characterized by elemental analysis and spectroscopy, and in the case of 4,6 and 16 also by X-ray diffraction techniques. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Investigation of the temperature oscillations in the cylinder walls of a diesel engine with special reference to the limited cooled caseINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2004C. D. Rakopoulos Abstract This work investigates the interesting phenomenon of the temperature (cyclic) oscillations in the combustion chamber walls of a diesel engine. For this purpose, a comprehensive simulation code of the thermodynamic cycle of the engine is developed taking into account both the closed and the open parts of it. The energy and state equations are applied, with appropriate combustion, gas heat transfer, and mass exchange with the atmosphere sub-models, to yield cylinder pressure, local temperatures and heat release histories as well as various performance parameters of the engine. The model is appropriately coupled to a wall periodic conduction model, which uses the gas temperature variation as boundary condition throughout the engine cycle after being treated by Fourier analysis techniques. It is calibrated against measurements, at various load and speed conditions, from an experimental work carried out on a direct injection (DI), naturally aspirated, four-stroke, diesel engine located at the authors' laboratory, which has been reported in detail previously. After gaining confidence into the predictive capabilities of the model, it is used to investigate the phenomenon further, thus providing insight into many interesting aspects of transient engine heat transfer, as far as the influence that engine wall material properties have on the values of cyclic temperature swings. These swings can take prohibitive values causing high wall thermal fatigue, when materials of specific technological interest such as thermal insulators (ceramics) are used, and may lead to deterioration in engine performance. Copyright © 2004 John Wiley & Sons, Ltd. [source] Binary copolymerization with full depropagation: A study of methyl methacrylate/,-methyl styrene copolymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2005M. J. Leamen Abstract The kinetics of the copolymerization of ,-methyl styrene and methyl methacrylate (MMA) have been revisited for the bulk system. Reactivity ratios and other kinetic parameter estimates based upon a copolymerization model developed by Kruger et al. (Makromol Chemie 1987, 188, 2163,2175) have been determined for a range of temperatures (60,140 °C). An interesting phenomenon has been uncovered, which shows that there is a distinct difference in copolymer composition predicted by the model when compared with experimental data at feed ratios of MMA below a critical value. This deviation also appears to be influenced by the reaction temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3868,3877, 2005 [source] Changing Nutrition Standards in Schools: The Emerging Impact on School RevenueJOURNAL OF SCHOOL HEALTH, Issue 5 2008Christopher M. Wharton PhD ABSTRACT Background:, Although great focus has been placed on nutritional and other consequences of changes in food-related policies within schools, few reports exist describing the impact of such changes on school revenue. This review provides an overview of the few revenue-related studies published recently, as well as information from a sampling of state reports on the subject. Methods:, A systematic review of the literature was conducted. Four peer-reviewed papers and 3 state-based reports were identified that assessed the impact on revenues of either targeted policy changes or overarching, district-wide changes in food-related policies. Results:, Thus far, few data exist to substantiate the concern that changes in nutrition standards in schools lead to a loss in total revenue. An interesting phenomenon of increased participation in the National School Lunch Program was noted in a number of reports and might play a role in buffering financial losses. Conclusions:, A renewed focus on school policies related to health provides the opportunity for researchers to investigate how nutrition-related policy change can affect, if at all, food service and overall school revenues. [source] Interwell exciton dispersion engineering, coherent phonons generation and optical detectionof exciton condensatePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2004Yu. E. Lozovik This issue's Editor's Choice [1] discusses interwell excitons in coupled quantum wells as a candidate for observation of different phases in an exciton system, including the very interesting phenomenon of Bose condensation. The cover picture shows schematically how the generation of coherent phonons and the angular distribution of the exciton photoluminescence (PL) from the quantum well system can be controlled by the external electric and magnetic fields. The first author, Yurii E. Lozovik, is head of the Laboratory of Spectroscopy of Nanostructures at the Institute of Spectroscopy and also Professor of Physics at the Moscow Physical and Technical Institute. His main interests are electron and electron,hole systems in nanostructures, cluster physics, quantum electrodynamics in a cavity, matter in strong magnetic fields, nanotechnology, ultrafast and near field optics, and computer simulations. [source] Introgressive hybridization in southern African baboons shapes patterns of mtDNA variationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010C. Keller Abstract Species, as main evolutionary units have long been considered to be morphological entities with limited hybridization potential. The occurrence of taxa which maintain morphological distinctness despite extensive hybridization is an interesting phenomenon. To understand the evolution of these taxa, descriptions of contemporary morphological and genetic variation are essential, also to reconstruct sound phylogenies. Baboons, with their wide geographic range, variant morphotypes, and extensive hybridization offer an intriguing model for those studies. We focus on the complex situation in southern Africa that, in contrast to east Africa, has been neglected in terms of baboon hybridization history. We aim to clarify the distribution and identify possible overlapping zones between different, previously described mitochondrial (mt) DNA clades of baboons that do not match with the ranges of traditionally recognized species. On the basis of the widespread sampling and mitochondrial cytochrome b gene sequencing, we constructed a phylogenetic tree that separates representatives of the two southern African baboon species, yellow and chacma baboons, into six clades: southern, northern and eastern chacmas, Kinda baboons and southern and Luangwa yellow baboons. The ranges of the chacma clades come into close contact or overlap in two regions in the Republic of South Africa and Namibia. Our phylogenetic reconstruction reveals mitochondrial paraphyly for chacma and yellow baboons, which is probably caused by introgressive hybridization and subsequent nuclear swamping, whereby males of the chacma morphotype population from the south invaded the yellow morphotype population in the north bringing their morphotype into a population that maintained its yellow baboon mtDNA. Am J Phys Anthropol 2010. © 2009 Wiley-Liss, Inc. [source] Front and Back Covers, Volume 25, Number 1.ANTHROPOLOGY TODAY, Issue 1 2009February 200 Front cover caption, volume 25 issue 1 A boy shows off on his horse at the annual festival of racing, games and music in Barsko'on, Kyrgyzstan in October 2007. The festival includes endurance races of up to 36 kilometres over steep, rocky mountain paths and streams, a far cry from the bowling-green surfaces of Churchill Downs and Newmarket. Abdildechan, an expert in horse games in Kyzyl Suu, explained that horse games and competitions such as these derive from the importance of horses to the nomadic and warrior traditions of the Kyrgyz people. Horses enable people to move away from danger, he explained, and are also essential for work and food. Cars are becoming increasingly common in Kyrgyzstan, but many people believe that they will never completely replace horses in this mountainous region. ,Young people may have cars', says shepherd Jakshylyck Orgochor, ,but where there is a Kyrgyz person there is always a horse: a horse is a man's wings'. In this issue, Rebecca Cassidy scrutinizes claims about the distinctiveness of the Kyrgyz horse and considers the political consequences of evaluating domesticated animals on the basis of contested categories including ,breed' and ,type'. Back Cover: HUMAN-ANIMAL RELATIONS Ros Coard, lecturer in archaeology and specialist in archaeozoology and forensic taphonomy in the Department of Archaeology and Anthropology at the University of Wales Lampeter, examines forensic evidence taken from the scene of a suspected big cat kill in West Wales, UK. The skulls in the foreground belong to an array of known big cat species, and Coard compared tooth pit data from these skulls with those found in sheep and horses killed in unusual circumstances. These data have been used to provide evidence for the existence of at least one large predatory felid in West Wales. However, even without this scientific corroboration, many people around the UK report sightings of non-endemic ,alien' big cats (ABCs) on a regular basis, attributing to them an almost mythical status, and this makes them an interesting phenomenon to be considered from an anthropological perspective. Coard has been working collaboratively with Samantha Hurn, an anthropologist who has been documenting narratives relating to big cat sightings in West Wales. In this issue of ANTHROPOLOGY TODAY, Hurn outlines the data collected so far. She argues that ABCs do, indeed, exist in West Wales, and discusses how and why her informants from the local Welsh farming community regard these predators in positive terms. Many see ABCs as both important keystone species performing the valuable function of keeping other problematic predators (notably foxes) in check, and highly politicized animals who symbolize their own marginalized position within contemporary UK society. As Lévi-Strauss put it long ago, animal-human relations are, indeed, good to think with. [source] Enhanced Fluorescence of Remote Functionalized Diaminodicyanoquinodimethanes in the Solid State and Fluorescence Switching in a Doped Polymer by Solvent VaporsCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2004S. Jayanty Abstract Remote functionalized zwitterionic diaminodicyanoquinodimethanes are found to exhibit a dramatic enhancement of light emission in the solid state and when doped in polymer films, as compared to the solution state. Crystal structure analysis of prototypical molecules reveals the role of the remote functionality in the solid state molecular organization. Semiempirical quantum chemical computations provide a viable model to explain the interesting phenomenon of fluorescence enhancement as arising from the inhibition of geometry relaxation of the vertical excited state to a nonemitting state. The reversible switching of a doped polymer film fluorescence triggered by solvent vapors is demonstrated. [source] | ||||||||||