bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deoxygenation of isocyanates via transient electrophilic terminal phosphinidene complexes: Are strained P‐heterocycles involved?
Authors: Schulten Christian , von Frantzius Gerd , Schnakenburg Gregor , Streubel Rainer 
Published: April 2011

AbstractSynthesis of 1,3,2,4σ3λ3−dioxadiphosphetane complexes 3a,b and 4a,b was achieved via thermal decomposition of 2H‐azaphosphirene complexes of chromium (1a) and tungsten (1b) in the presence of tert‐butyl isocyanate; as reactive intermediates 3‐imino‐oxaphosphirane complexes 8a,b are proposed, which decompose to give phosphinidene oxide complexes 9a,b. The intermediacy of the latter is inferred from a cross‐dimerization experiment (decomposition of a 1:1 mixture of 2H‐azaphosphirene complexes 1a,b with tert‐butyl isocyanate), which furnished the mixed metal dinuclear cis and trans complexes 5a/b and 6a/b. 31P NMR spectroscopy revealed the formation of [bis(trimethylsilyl)methyl]cyanophosphane complexes 11a,b as by‐products. Thermal reaction of complex 1b with the less bulky ethyl isocyanate furnished the novel 1,3,4σ3λ3‐diazaphospholidin‐5‐imin‐2‐one complex 7 together with complexes 3b and 4b. For the latter case, 3‐imino‐oxaphosphirane (12) and azaphosphiridin‐3‐one (13) complexes are proposed as reactive intermediates. All final products were characterized by multinuclear NMR spectroscopy, IR, MS, and single‐crystal X‐ray crystallography in the cases of complexes 3b and 4a,b. DFT calculations strongly support the transient formation and decomposition of 3‐imino‐oxaphosphirane complex 12 to form 9b and isonitrile. Azaphosphiridin‐3‐one complex 13 was characterized computationally as the methyl model. In accordance with the calculations, final products 1,3,2,4σ3λ3‐dioxadiphosphetane complexes 3a,b and 4a,b form by dimerization of transient terminal phosphinidene oxide complexes 9a,b. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:275–286, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20677
Electrochemically switchable supramolecular complex between bisporphyrin cleft and electron‐deficient aromatic guest
Authors: Ikeda Toshiaki , Watanabe Akihide , Oshita Tomoko , Haino Takeharu 
Published: April 2011

AbstractThe host–guest complexation between bisporphyrin cleft 1 and flat aromatic guest 2 was controlled by an electrochemical reaction. The first oxidation potentials of 1 showed the anodic shift upon the addition of 2. On the basis of the square scheme, the association constant of 1 with 2 was estimated to be at least 50 times larger than that of cation radical 12·+ with 2. This demonstrated that the electrochemical oxidation obviously reduced the binding ability of 1. The reversible nature of the switchable complexation between 1 and 2 was confirmed by cyclic voltammetry. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:590–593, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20702
Synthesis and reactivities of dihydrosilanes tethered with two thioether moieties
Authors: Takeda Nobuhiro , Nakamura Tetsu , Imamura Ayako , Unno Masafumi 
Published: April 2011

AbstractDihydrosilanes tethered with two thioether moieties, [2‐(RSCH2)C6H4]2SiH2(1a: R = t‐Bu; 1b: R = i‐Pr; 1c: R = Ph), were synthesized. Dihydrosilane 1b did not react with methanol, benzaldehyde, and carboxylic acids; this result may suggest very weak activation of the SiH bonds in 1b. The corresponding dibromosilanes 4 and diiodosilanes 5 were synthesized by dihalogenation of 1 using N‐bromosuccinimide and I2, respectively, whereas the dichlorosilanes 3 were synthesized by reaction of 2‐(RSCH2)C6H4 Li with SiCl4. Reaction of 1b with [PtCl2 (cod)] in the presence of Et3N gave the corresponding bissilylplatinum complex, [Pt{SiH[2‐(RSCH2)‐ C6H4]2}2], the structure of which was determined by NMR and IR spectrometry and X‐ray crystallography. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:438–445, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20706
Effects of heterole spacers on the structural, optical, and electrochemical properties of 2,5‐bis(1,5‐diphenylphosphol‐2‐yl)heteroles
Authors: Matano Yoshihiro , Saito Arihiro , Fujita Masato , Imahori Hiroshi 
Published: April 2011

Abstract2,5‐Bis(1,5‐diphenylphosphol‐2‐yl)he‐terole derivatives were prepared via Pd‐catalyzed Stille‐type cross‐coupling reactions of α‐(tributylstannyl) phosphole or α‐iodophosphole with the corresponding 2,5‐difunctionalized heteroles (pyrrole, furan, and thiophene). X‐ray crystallographic analyses of three σ4‐P derivatives have elucidated that the coplanar phosphole‐heterole‐phosphole π‐networks are constructed in both anti–anti and syn–anti conformations. In the case of the pyrrole‐linked σ4‐P derivatives, there is a weak hydrogen‐bonding interaction between NH and P=X (X = O, S) groups. The optical and electrochemical properties of the σ3‐P and σ4‐P=O derivatives were revealed experimentally by means of UV–vis absorption/emission spectroscopy and cyclic/differential pulse voltammetry. In all the heterole‐linked derivatives, the P‐oxidation lowers LUMO levels more efficiently than HOMO levels and, as a result, narrows HOMO–LUMO gaps. In each series (σ3‐P or σ4‐P=O), the lowest π–π* transition energies of the phosphole–heterole–phosphole π‐systems were found to decrease in the following order: thiophene > furan > pyrrole, and their electrochemical oxidation and reduction potentials shift to the negative side in the same order. These results basically reflect the differences in ionization potential and electron affinity of the central heterole spacers. Density functional theory calculations on the model compounds supported the experimentally observed results. The HOMO of the molecule resides on the conjugated polyene network of the π‐system, whereas the LUMO is strongly located on the phosphole subunits. The present comparative study demonstrates, for the first time, that the intriguing electronic structures and the fundamental properties of the 2,5‐bis(1,5‐diphenylphosphol‐2‐yl)heteroles can be finely tuned by simple selection of the appropriate heterole spacer. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:457–470, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20708
Reaction ofo‐(HSiR2)(BMes2)C6H4with a fluoride ion: Fluoride attack at silicon and hydride transfer from silicon to boron to form FSi⋅⋅⋅HB interaction
Authors: Kawachi Atsushi , Morisaki Hiroshi , Tani Atsushi , Zaima Masatoshi , Yamamoto Yohsuke 
Published: April 2011

AbstractReactions ofo‐(HSiR2)(BMes2)C6H4(R = Me (3a), Ph (3b)) with a fluoride ion afford [o‐(FSiR2)(HBMes2)C6H4]−(R = Me (5a), Ph (5b)), which involve the FSi⋅⋅⋅HB interaction to render the silicon atom pentacoordinate. The FSi⋅⋅⋅HB interaction in5awas confirmed by X‐ray crystallographic analysis and “atoms‐in‐molecules” (AIM) analysis. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:471–475, 2011; View this article online atwileyonlinelibrary.com. DOI 10.1002/hc.20709
A study of hippocampal structure‐function relations along the septo‐temporal axis
Authors: Jarrard Leonard E. , Luu Lisa P. , Davidson Terry L. 
Published: April 2011

AbstractThis study examined structural–functional differences along the septo‐temporal axis of hippocampus using radial‐maze tasks that involved two different memory processes [reference memory (RM) and working memory (WM)], and the use of two kinds of information (spatial vs. nonspatial cue learning). In addition, retention of the nonspatial cue task was tested nine weeks following completion of acquisition, and the rats then underwent discrimination reversal training. Ibotenic acid lesions limited to either the dorsal pole, intermediate area, or ventral pole had minimal effects on acquisition of the complex place and cue discrimination tasks. The one exception was that rats with lesions confined to the dorsal third of hippocampus made more WM errors on the spatial task (but not the cue task) early in training. Selective lesions of the three hippocampal regions had no effects on either long‐term retention or reversal of the nonspatial cue discrimination task. In contrast, rats that had all of the hippocampus removed were severely impaired in learning the spatial task, making many RM and WM errors, whereas on the nonspatial cue task, the impairment was limited to WM errors. Further analysis of the WM errors made in acquisition showed that rats with complete lesions were significantly more likely on both the spatial and nonspatial cue tasks to reenter arms that had been baited and visited on that trial compared to arms that had not been baited. A similar pattern of errors emerged for complete hippocampal lesioned rats during reversal discrimination. This pattern of errors suggests that in addition to an impairment in handling spatial information, complete removal of hippocampus also interferes with the ability to inhibit responding to cues that signal reward under some conditions but not under others. The finding that selective lesions limited to the intermediate zone of the hippocampus produce no impairment in either WM (“rapid place learning”) or RM in our radial maze tasks serve to limit the generality of the conclusion of Bast et al. (Bast et al. (2009) PLos Biol 7:730‐746) that the intermediate area is needed for behavioral performance based on rapid learning about spatial cues. © 2011 Wiley Periodicals, Inc.
Greater running speeds result in altered hippocampal phase sequence dynamics
Authors: Maurer Andrew P. , Burke Sara N. , Lipa Peter , Skaggs William E. , Barnes Carol A. 
Published: April 2011

AbstractHebb (1949) described a “phase sequence” to be the sequential activation of sets of cell assemblies. Within the hippocampus, cell assemblies have been described as groups of coactive neurons whose place fields overlap. Membership of assemblies in a phase sequence changes systematically as a rat travels through an environment, serving to accelerate the temporal order that place fields are encountered during a single theta cycle. This sweeping forward of network activity (“look ahead”), results in locations in front of the animal being transiently represented. In this experiment, a population vector‐based reconstruction method was used to capture the look ahead and reveals that the composition of the phase sequence changes with velocity, such that more cell assemblies are active within a theta cycle at higher running speeds. These results are consistent with hypotheses suggesting that hippocampal networks generate short time scale predictions of future events to optimize behavior. © 2011 Wiley Periodicals, Inc.
5‐HT1A and 5‐HT7 receptors differently modulate AMPA receptor‐mediated hippocampal synaptic transmission
Authors: Costa L. , Trovato C. , Musumeci S.A. , Catania M.V. , Ciranna L. 
Published: April 2011

AbstractWe have studied the effects of 5‐HT1A and 5‐HT7 serotonin receptor activation in hippocampal CA3‐CA1 synaptic transmission using patch clamp on mouse brain slices. Application of either 5‐HT or 8‐OH DPAT, a mixed 5‐HT1A/5‐HT7 receptor agonist, inhibited AMPA receptor‐mediated excitatory post synaptic currents (EPSCs); this effect was mimicked by the 5‐HT1A receptor agonist 8‐OH PIPAT and blocked by the 5‐HT1A antagonist NAN‐190. 8‐OH DPAT increased paired‐pulse facilitation and reduced the frequency of mEPSCs, indicating a presynaptic reduction of glutamate release probability. In another group of neurons, 8‐OH DPAT enhanced EPSC amplitude but did not alter paired‐pulse facilitation, suggesting a postsynaptic action; this effect persisted in the presence of NAN‐190 and was blocked by the 5‐HT7 receptor antagonist SB‐269970. To confirm that EPSC enhancement was mediated by 5‐HT7 receptors, we used the compound LP‐44, which is considered a selective 5‐HT7 agonist. However, LP‐44 reduced EPSC amplitude in most cells and instead increased EPSC amplitude in a subset of neurons, similarly to 8‐OH DPAT. These effects were respectively antagonized by NAN‐190 and by SB‐269970, indicating that under our experimental condition LP‐44 behaved as a mixed agonist. 8‐OH DPAT also modulated the current evoked by exogenously applied AMPA, inducing either a reduction or an increase of amplitude in distinct neurons; these effects were respectively blocked by 5‐HT1A and 5‐HT7 receptor antagonists, indicating that both receptors exert a postsynaptic action. Our results show that 5‐HT1A receptors inhibit CA3‐CA1 synaptic transmission acting both pre‐ and postsynaptically, whereas 5‐HT7 receptors enhance CA3‐CA1 synaptic transmission acting exclusively at a postsynaptic site. We suggest that a selective pharmacological targeting of either subtype may be envisaged in pathological loss of hippocampal‐dependent cognitive functions. In this respect, we underline the need for new selective agonists of 5‐HT7 receptors. © 2011 Wiley Periodicals, Inc.
Influence of vestibular input on spatial and nonspatial memory and on hippocampal NMDA receptors
Authors: Besnard S. , Machado M.L. , Vignaux G. , Boulouard M. , Coquerel A. , Bouet V. , Freret T. , Denise P. , Lelong‐Boulouard V. 
Published: April 2011

AbstractIt has recently been shown that a lack of vestibular sensory information decreases spatial memory performance and induces biochemical changes in the hippocampus in rodents. After vestibular neurectomy, patients display spatial memory deficit and hippocampal atrophy. Our objectives were to explore: (a) spatial (Y maze, radial‐arm maze), and non‐spatial (object recognition) memory performance, (b) modulation of NMDA receptors within the hippocampus using radioligand binding, and (c) hippocampal atrophy, using MRI, in a rat model of bilateral labyrinthectomy realized in two operations. Chemical vestibular lesions (VLs) were induced in 24 animals by transtympanic injections of sodium arsanilate (30 mg/0.1 ml/ear), one side being lesioned 3 weeks after the other. The control group received transtympanic saline solution (0.1 ml/ear) (n= 24). Spatial memory performance (Y maze and radial maze) decreased after VL. Conversely, non‐spatial memory performance (object recognition) was not affected by VL. No hippocampal atrophy was observed with MRI, but density of NMDA receptors were increased in the hippocampus after VL. These findings show that the lack of vestibular information induced specific deficits in spatial memory. Additionally, quantitative autoradiographic data suggest the involvement of the glutamatergic system in spatial memory processes related to vestibular information. When studying spatial memory performances in the presence of vestibular syndrome, two‐step labyrinthectomy is a suitable procedure for distinguishing between the roles of the specific components of vestibular input loss and those of impaired locomotor activity. © 2011 Wiley Periodicals, Inc.
A broad‐scale assessment of the effect of improved soil management on catchment baseflow index
Authors: Holman I. P. , Hess T. M. , Rose S. C. 
Published: April 2011

AbstractAlthough the importance of sustainable soil management is recognized, there are many threats to soils including widespread soil structural degradation. This reduces infiltration through the soil surface and/or the percolation of water through the soil profile, with important consequences for crop yields, nutrient cycling and the hydrological response of catchments. This article describes a broad‐scale modelling approach to assess the potential effect that improved agricultural soil management, through reduced soil structural degradation, may have on the baseflow index (BFI) of catchments across England and Wales. A daily soil–water balance model was used to simulate the indicative BFI of 45 696 thirty‐year model runs for different combinations of soil type, soil/field condition, land cover class and climate which encapsulate the variability across England and Wales. The indicative BFI of catchments was then calculated by upscaling the results by spatial weighting. WaSim model outputs of indicative BFI were within the 95% confidence intervals of the national‐average BFI values given for the Hydrology of Soil Type (HOST†) classes for 26 of the 28 classes. At the catchment scale, the concordance correlation coefficient between the BFI from the WaSim model outputs and those derived from HOST was 0·83. Plausible improvements in agricultural soil/field condition produced modest simulated increases of up to 10% in the indicative BFI in most catchments across England and Wales, although for much of southern and northern England the increases were less than 5%. The results suggest that improved soil management might partially mitigate the expected adverse effects of climate change on baseflow to rivers. Healthy, well‐functioning soils produce many additional benefits such as better agricultural yields and reduced pollutant movement, so improved soil management should provide win‐win opportunities for society, agricultural systems and the environment and provide resilience to some of the expected environmental impacts of climate change. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization of the infiltration rate in Las Tablas de Daimiel National Park, Central Spain
Authors: Navarro Vicente , García Beatriz , Asensio Laura 
Published: April 2011

AbstractThis article presents the characterization of the infiltration rate in the area known as ‘Las Cañas’ which is part of Las Tablas de Daimiel National Park, Central Spain. Available information was used for direct identification and while the results varied widely, it was proven that a functional dependence exists between the infiltration rate and the inundated area. After examining the structure of this dependence more closely, the most appropriate model was deemed to be a bilinear model. With these basic foundations, data from years 1997, 1998, 2003 and 2005 were used to identify the three parameters of the model. Highly satisfactory identifications were obtained. The model was then calibrated and the drying processes from 1996, 2000 and 2003 were simulated with considerable accuracy since the standard deviation was only 4 ha for a total of 400 inundated ha. The model was used to estimate the evolution that the inundated area would undergo after introducing contributions of treated sewage effluents. Even though it was assumed that the results would entail twice as many errors as the standard deviation, they did, however, allow us to provide a concise description of the behaviour of the system. Consequently, elements of judgement that highlight the advisability of the application of treated sewage effluents in Las Cañas, from a hydrological standpoint, were obtained. Copyright © 2011 John Wiley & Sons, Ltd.
Quantifying trends in indicator hydroecological variables for regime‐based groups of Canadian rivers
Authors: Monk Wendy A. , Peters Daniel L. , Allen Curry R. , Baird Donald J. 
Published: April 2011

AbstractAs a key contribution to Canada's Ecosystem Status and Trends (ESTR) national assessment, the goal of our study was to utilize available flow data as a surrogate of habitat suitability for aquatic ecological communities, and examine temporal trends in hydroecological variables over the 1970–2005 period. Daily flow data were extracted from the Reference Hydrological Basin Network, and an agglomerative hierarchical classification method was used to identify homogenous regions with similar seasonality of the flow regime. Six regime regions were identified reflecting the timing of the annual peaks and low flows in addition to the patterns in the rising and falling limbs. For each of the gauging station sites, the magnitude, duration, timing, frequency, and rate of change of annual hydrological events were quantified through 32 ecologically important hydrological variables. Long‐term patterns in the hydroecological variables were quantified using the nonparametric Mann‐Kendall trend statistic. The results revealed more trends than would be expected to occur by chance for most variables. Clear regional trend patterns were observed within individual regime groups demonstrating the often differing response to environmental variability within the different regions. Results at the national scale were highly variable, but trends towards increased variability in river flows were observed with a predominant increasing trend in the number of flow reversals over the water year and decreasing trend in the annual low‐flow indices. The identified river regime regions offer an initial framework for scientific investigation of hydroecological patterns and an opportunity to move towards a more predictive approach to environmental flows assessment in sustainable resource management and planning. Copyright © 2011 John Wiley & Sons, Ltd.
Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India
Authors: Garg Kaushal K. , Karlberg Louise , Barron Jennie , Wani Suhas P. , Rockstrom Johan 
Published: April 2011

AbstractThe paper describes a hydrological model for agricultural water intervention in a community watershed at Kothapally in India, developed through integrated management and a consortium approach. The impacts of various soil and water management interventions in the watershed are compared to no‐intervention during a 30‐year simulation period by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Kothapally receives, on average, 800 mm rainfall in the monsoon period. 72% of total rainfall is converted as evaporation and transpiration (ET), 20% is stored by groundwater aquifer, and 8% exported as outflow from the watershed boundary in current water interventions. ET, groundwater recharge and outflow under no‐intervention conditions are found to be 64, 9, and 19%, respectively. Check dams helped in storing water for groundwater recharge, which can be used for irrigation, as well minimising soil loss. In situ water management practices improved the infiltration capacity and water holding capacity of the soil, which resulted in increased water availability by 10–30% and better crop yields compared to no‐intervention. Water outflows from the developed watershed were more than halved compared to no‐intervention, indicating potentially large negative downstream impacts if these systems were to be implemented on a larger scale. On the other hand, in the watershed development program, sediment loads to the streams were less than one‐tenth. It can be concluded that the hydrological impacts of large‐scale implementation of agricultural water interventions are significant. They result in improved rain‐fed agriculture and improved productivity and livelihood of farmers in upland areas while also addressing the issues of poverty, equity, and gender in watersheds. There is a need for case‐specific studies of such hydrological impacts along with other impacts in terms of equity, gender, sustainability, and development at the mesoscale. Copyright © 2011 John Wiley & Sons, Ltd.
Trends in reference evapotranspiration in the humid region of northeast India
Authors: Jhajharia Deepak , Dinpashoh Yagob , Kahya Ercan , Singh Vijay P. , Fakheri‐Fard Ahmad 
Published: April 2011

AbstractIn the present study, the trends in the reference evapotranspiration (ETO) estimated through the Penman‐Monteith method were investigated over the humid region of northeast (NE) India by using the Mann‐Kendall (MK) test after removing the effect of significant lag‐1 serial correlation from the time series of ETO by pre‐whitening. During the last 22 years, ETO has been found to decrease significantly at annual and seasonal time scales for 6 sites in NE India and NE India as a whole. The seasonal decreases in ETO have, however, been more significant in the pre‐monsoon season, indicating the presence of an element of a seasonal cycle. The decreases in ETO are mainly attributed to the net radiation and wind speed, which are also corroborated by the observed trends in these two parameters at almost all the times scales over most of the sites in NE India. The steady decrease in wind speed and decline in net radiation not only balanced the impact of the temperature increases on ETO, but may have actually caused the decreases in ETO over the humid region of northeast India. Copyright © 2011 John Wiley & Sons, Ltd.