bluuebunny/crossref_metadata_2025 huggingface dataset:
Multimodal Imaging of Alzheimer Pathophysiology in the Brain′s Default Mode Network
Authors: Shin Jonghan , Kepe Vladimir , Small Gary W. , Phelps Michael E. , Barrio Jorge R.
Published: April 2011

The spatial correlations between the brain′s default mode network (DMN) and the brain regions known to develop pathophysiology in Alzheimer′s disease (AD) have recently attracted much attention. In this paper, we compare results of different functional and structural imaging modalities, including MRI and PET, and highlight different patterns of anomalies observed within the DMN. Multitracer PET imaging in subjects with and without dementia has demonstrated that [C‐11]PIB‐ and [F‐18]FDDNP‐binding patterns in patients with AD overlap within nodes of the brain′s default network including the prefrontal, lateral parietal, lateral temporal, and posterior cingulate cortices, with the exception of the medial temporal cortex (especially, the hippocampus) where significant discrepancy between increased [F‐18]FDDNP binding and negligible [C‐11]PIB‐binding was observed. [F‐18]FDDNP binding in the medial temporal cortex—a key constituent of the DMN—coincides with both the presence of amyloid and tau pathology, and also with cortical areas with maximal atrophy as demonstrated by T1‐weighted MR imaging of AD patients.
Cobalt Ferrite Nanocrystallites for Sustainable Hydrogen Production Application
Authors: Gaikwad Rajendra S. , Chae Sang-Youn , Mane Rajaram S. , Han Sung-Hwan , Joo Oh-Shim
Published: April 2011

Cobalt ferrite, CoFe2O4, nanocrystalline films were deposited using electrostatic spray method and explored in sustainable hydrogen production application. Reflection planes in X-ray diffraction pattern confirm CoFe2O4phase. The surface scanning microscopy photoimages reveal an agglomeration of closely-packed CoFe2O4nanoflakes. Concentrated solar-panel, a two-step water splitting process, measurement technique was preferred for measuring the hydrogen generation rate. For about 5 hr sustainable, 440 mL/hr, hydrogen production activity was achieved, confirming the efficient use of cobalt ferrite nanocrystallites film in hydrogen production application.
Circadian Variations in Blood Pressure, Heart Rate, and HR-BP Cross-Correlation Coefficient during Progression of Diabetes Mellitus in Rat
Authors: Anigbogu Chikodi N. , Williams Daniel T. , Brown David R. , Silcox Dennis L. , Speakman Richard O. , Brown Laura C. , Karounos Dennis G. , Randall David C.
Published: April 2011

Circadian changes in cardiovascular function during the progression of diabetes mellitus in the diabetes prone rat (BBDP) (n=8) were studied. Age-matched diabetes-resistant rats (BBDR) served as controls. BP was recorded via telemetry in contiguous 4 hr time periods over 24 hours starting with 12 midnight to 4 am as period zero (P0). Prior to onset of diabetes BP was high at P0, peaked at P2, and then fell again at P3; BP and heart rate (HR) then increased gradually at P4 and leveled off at P5, thereby exhibiting a bipodal rhythm. These patterns changed during long-term diabetes. The cross-correlation coefficient of BP and HR was not significantly different across groups at onset, but it fell significantly at 9 months of duration of diabetes (BBDP: 0.39 ± 0.06; BBDR: 0.65 ± 0.03;P<.05). These results show that changes in circadian cardiovascular rhythms in diabetes mellitus became significant at the late stage of the disease.
Prevalence of Hypertension, Obesity, Diabetes, and Metabolic Syndrome in Nepal
Authors: Sharma Sanjib Kumar , Ghimire Anup , Radhakrishnan Jeyasundar , Thapa Lekhjung , Shrestha Nikesh Raj , Paudel Navaraj , Gurung Keshar , R Maskey , Budathoki Anjali , Baral Nirmal , Brodie David
Published: April 2011

Background. This study was carried out to establish the prevalence of cardiovascular risks such as hypertension, obesity, and diabetes in Eastern Nepal. This study also establishes the prevalence of metabolic syndrome (MS) and its relationships to these cardiovascular risk factors and lifestyle.Methods. 14,425 subjects aged 20–100 (mean 41.4 ± 15.1) were screened with a physical examination and blood tests. Both the International Diabetic Federation (IDF) and National Cholesterol Education Programme’s (NCEP) definitions for MS were used and compared.Results. 34% of the participants had hypertension, and 6.3% were diabetic. 28% were overweight, and 32% were obese. 22.5% of the participants had metabolic syndrome based on IDF criteria and 20.7% according to the NCEP definition. Prevalence was higher in the less educated, people working at home, and females. There was no significant correlation between the participants’ lifestyle factors and the prevalence of MS.Conclusion. The high incidence of dyslipidemia and abdominal obesity could be the major contributors to MS in Nepal. Education also appears to be related to the prevalence of MS. This study confirms the need to initiate appropriate treatment options for a condition which is highly prevalent in Eastern Nepal.
Rapid Electrochemical Detection of Radiolysis Products in an Aqueous Solution Exposed to Alpha Particle Beams
Authors: Liedhegner J. E. , Jennings W. , Wainright J.
Published: April 2011

An electrochemical cell has been developed that allows for the rapid and exhaustive detection of oxygen and/or hydrogen peroxide produced during the radiolysis of aqueous solutions by alpha particle or proton beams. Short, 10–100 s, exposures were sufficient to yield steady-state electrochemical currents proportional to the radiolysisG-factor. The use of thin SiC windows provided a robust means of separating the vacuum environment of the ion-beam accelerator from the aqueous solution at atmospheric pressure with minimal energy loss.
Rapid Increase of the Serum PSA Level in Response to High-Intensity Focused Ultrasound Therapy may be a Potential Indicator of Biochemical Recurrence of Low- and Intermediate-Risk Prostate Cancer
Authors: Inamoto Teruo , Komura Kazumasa , Watsuji Toshikazu , Azuma Haruhito
Published: April 2011

Objectives

To determine the incidence and magnitude of the rapid increase in the serum PSA (riPSA) level after high-intensity focused ultrasound (HIFU) therapy for prostate cancer, and its correlation with clinical factors.

Methods

A total of 176 patients with localized prostate cancer underwent HIFU therapy. Serum riPSA was determined on the basis of the same criteria as those for “PSA bounce”, ie, an increase of ≥0.2 ng/ml with a spontaneous return to the prebounce level or lower. Patients were stratified according to neoadjuvant PSA level, T stage, risk group, age, Gleason score, pretreatment PSA level, post-treatment PSA nadir, and number of HIFU sessions.

Results

riPSA was seen in 53% of patients during a median follow-up period of 43 months. A PSA nadir was achieved within 3 months for 85.1% of the treatments. In all cases, onset of riPSA was seen two days after HIFU therapy, and the median magnitude was 23.69 ng/ml. A magnitude of >2 ng/ml was seen in 89.4% of cases. Univariate analysis revealed that patients with riPSA were associated with usage of hormonal therapy and the post-treatment PSA nadir level. Multivariate Cox regression analysis revealed that riPSA and the number of HIFU sessions were predictors of biochemical recurrence. A significant statistical association was found between the presence of riPSA and the risk of biochemical failure only in the low- and intermediate-risk group.

Conclusion

Patients treated with HIFU who experience post-treatment riPSA may have an increased risk of biochemical recurrence, especially in non-high-risk patients.
Food quality of anemophilous plant pollen for zooplankton
Authors: Masclaux Hélène , Bec Alexandre , Kagami Maiko , Perga Marie-Elodie , Sime-Ngando Telesphore , Desvilettes Christian , Bourdier Gilles
Published: April 2011

Pollen rain can lead to considerable allochthonous particulate organic carbon input into freshwater systems. However, the importance of allochthonous pollen deposition for zooplankton production has not so far been considered. Here, standardized growth experiments were performed to assess the quality of pollen from three species (Alnus sp., Populus sp., and Cedrus sp.) as a food source for two cladocerans (Daphnia longispina and Simocephalus vetulus). Although lipid analysis revealed high polyunsaturated fatty acid (PUFA) contents in pollen, both cladoceran species exhibited suboptimal development when directly fed on pollen (ranging from 0.2 d−1 to 0.3 d−1). The low food value of pollen was attributed to the presence of a refractory wall reducing its digestibility. In a second set of experiments, cladocerans were fed on a mixture of heterotrophic microorganisms (bacteria, chytrids, and protozoa) that had grown on pollen grains (Cedrus sp.). The introduction of microorganisms as an intermediate trophic level resulted in cladoceran growth rates that were about double those obtained on pollen alone. Hence, our findings suggest that pollen carbon could sustain zooplankton growth indirectly, and highlight the key role of microorganisms, and especially of chytrids, in transferring and upgrading pollen PUFA to higher trophic levels.
Rapid gain and loss of evolutionary resistance to the harmful dinoflagellate Cochlodinium polykrikoides in the copepod Acartia tonsa
Authors: Jiang Xiaodong , Lonsdale Darcy J. , Gobler Christopher J.
Published: April 2011

Evolutionary resistance of the copepod Acartia tonsa to the dinoflagellate Cochlodinium polykrikoides was investigated to establish whether zooplankton can rapidly adapt to harmful algal blooms (HABs). Copepod resistance was evaluated by egg production rates when feeding on C. polykrikoides relative to the nontoxic flagellate Rhodomonas lens. An experiment with six geographically separate A. tonsa populations demonstrated that the copepods collected during C. polykrikoides blooms within eastern Long Island bays were significantly more resistant to C. polykrikoides than their conspecifics in nearby nonbloom regions. An artificial selection experiment with a naïve A. tonsa population demonstrated that copepod resistance significantly increased when individuals were chronically exposed to C. polykrikoides (three times greater than the control after four generations). Following a two‐generation relaxation of selection, however, the elevated resistance in A. tonsa was completely lost. Such rapid gain and loss of resistance suggests that copepod adaptation to C. polykrikoides in the bays of eastern Long Island may mainly result from the selection of resistant genotypes by an ongoing bloom event rather than prior HABs, which could shape trophic interactions between zooplankton and harmful algae.
Variability in optical particle backscattering in contrasting bio‐optical oceanic regimes
Authors: Antoine David , Siegel David A. , Kostadinov Tihomir , Maritorena Stéphane , Nelson Norm B. , Gentili Bernard , Vellucci Vincenzo , Guillocheau Nathalie
Published: April 2011

Variability in the optical particle backscattering coefficient (bbp) is investigated in oceanic waters from two sites, namely the BOUée pour l'acquiSition d'une Série Optique à Long termE site in the northwestern Mediterranean Sea and the Plumes and Blooms stations in the Santa Barbara Channel off Southern California. Data from these two sites span two orders of magnitude in bbp and likely cover typical open ocean values. A significant relationship is found between bbp at wavelengths of 442 and 555 nm and chlorophyll concentration. However the large spread in this relationship makes chlorophyll a poor predictor of bbp. The relationship between bbp and the particulate beam attenuation coefficient at 660 nm is tighter for both sites, indicating covariability of the particle size ranges that determine both coefficients. A detailed study of the seasonal changes of the bbp vs. chlorophyll relationship reveals that this bio‐optical relationship might be best described as a succession of distinct regimes with rapid transitions from one to another. The backscattering ratio (b~bp; the ratio of bbp to total particulate scattering, bp) ranges from about 0.2% to 1.5%, which is similar to previously reported values. The relationship between b~bp and chlorophyll was not significant, while values of the backscattering ratio varied spectrally.
Shifts in limiting nutrients in an estuary caused by mixing and biological activity
Authors: Lui Hon-Kit , Chen Chen-Tung Arthur
Published: April 2011

Simple general equations are used to show that when riverine water mixes with seawater, the N : P ratio is a nonlinear function of salinity. Thus, a shift in the limiting‐nutrient status at a particular salinity along a continuum is a mathematical certainty, albeit complicated by biological consumption and remineralization. The salinity where the shift occurs is a function of biological nutrient uptake ratio. Four general modes, each with a corresponding formula, are deduced here to explain the factors that govern changes in nutrient ratios vs. salinity. These formulas help to explain why changes in the seasonal nutrient limitation status in some estuaries are in some cases triggered by variations in nutrient loading, and in other cases by mixing.
Long‐term effects of salinity and disturbance regime on active and dormant crustacean communities
Authors: Waterkeyn Aline , Vanschoenwinkel Bram , Vercampt Hanne , Grillas Patrick , Brendonck Luc
Published: April 2011

In a large‐scale and long‐term outdoor mesocosm (400‐liter) experiment, we studied the interacting effects of salinity and disturbance (hydrological) regime on the active and dormant crustacean communities of Mediterranean temporary wetlands (Camargue, southern France). Sixty‐four mesocosms, inoculated with a regional species pool (mixed dormant egg banks), were exposed to a full factorial treatment combination of four salinity levels and four disturbance regimes during three consecutive years. Both in the active and dormant community component, considerable shifts in community composition occurred because of direct and probably also second‐order effects of the treatments. All large branchiopod species had low long‐term salinity tolerances and showed species‐specific preferences for disturbance regimes according to their life cycle strategy. The highest salinity (5) was not limiting for cladocerans and ostracods, which thrived in the absence of the competitively stronger, predatory, and bioturbating large branchiopods. Copepods were negatively associated with salinity and coped better with the imposed biotic pressure. Zooplankton diversity and density peaked in intermediate‐disturbance regimes, probably because only specialized species survived the high‐disturbance regimes, whereas at low‐disturbance frequencies high densities of predatory Triops controlled zooplankton communities. Although crustacean dormant egg banks can temporarily buffer against unfavorable conditions, persisting bad conditions may lead to their exhaustion within 4 to 10 yr. Predicted aridification (leading to more intense disturbance regimes) may result in the loss of late successional species (chydorids and ostracods), whereas salinization may wipe out sensitive freshwater species such as large branchiopods.
Foundation or Fragment of Local Democracy? Empirically Assessing the Roles of Local Councillors in Belgian Governance
Authors: Verhelst Tom , Reynaert Herwig , Steyvers Kristof
Published: April 2011

It is often argued that local governance conflicts with the prescribed functioning of local councillors. We could wonder if councillors have become fragments of local democracy, rather than the foundation they are supposed to be. This article empirically assesses the classic role-set (representation, policy, control) of local councillors in Belgian governance. Besides pointing to a gap between theory and practice, it underlines a substantial discrepancy between councillors’ role attitude and subsequent behaviour. This democratic deficit seems mainly due to the informal decision-making culture in Belgian (local) politics, i.e. the dominance of the local executive and stringent party discipline.

Keywords: • local councillors • role-set • governance • democratic deficit • Belgium
Opportunities for and Barriers to Cooperation between Employers and Employment Offices in the Czech Republic: Employers’ Perspective
Authors: Klimplová Lenka
Published: April 2011

The aim of this paper is to present and analyze opportunities for and barriers to cooperation between private employers and public employment offices in the Czech Republic, from the employers’ perspective. Based on research results, opportunities for cooperation can be seen in attitudes of employment officers towards employers, individualization and differentiation of approaches, better mutual awareness etc., but also in successive changes of some legislative and institutional factors. The barriers to cooperation, on the other hand, can be seen in hardly removable structural factors, such as the structure and characteristics of jobseekers, divergence of goals and lack of mutual interdependence.

Keywords: • cooperation • public-private partnership • opportunities • barriers • employment office • employers • Czech Republic
Dayside magnetopause transients correlated with changes of the magnetosheath magnetic field orientation
Authors: Tkachenko O. , Šafránková J. , Němeček Z. , Sibeck D. G.
Published: April 2011

Abstract. The paper analyses one long-term pass (26 August 2007) of the THEMIS spacecraft across the dayside low-latitude magnetopause. THEMIS B, serving partly as a magnetosheath monitor, observed several changes of the magnetic field that were accompanied by dynamic changes of the magnetopause location and/or the structure of magnetopause layers observed by THEMIS C, D, and E, whereas THEMIS A scanned the inner magnetosphere. We discuss the plasma and the magnetic field data with motivation to identify sources of observed quasiperiodic plasma transients. Such events at the magnetopause are usually attributed to pressure pulses coming from the solar wind, foreshock fluctuations, flux transfer events or surface waves. The presented transient events differ in nature (the magnetopause surface deformation, the low-latitude boundary layer thickening, the crossing of the reconnection site), but we found that all of them are associated with changes of the magnetosheath magnetic field orientation and with enhancements or depressions of the plasma density. Since these features are not observed in the data of upstream monitors, the study emphasizes the role of magnetosheath fluctuations in the solar wind-magnetosphere coupling.
Using synoptic type analysis to understand New Zealand climate during the Mid-Holocene
Authors: Ackerley D. , Lorrey A. , Renwick J. A. , Phipps S. J. , Wagner S. , Dean S. , Singarayer J. , Valdes P. , Abe-Ouchi A. , Ohgaito R. , Jones J. M.
Published: April 2011

Abstract. Diagnosing the climate of New Zealand from low-resolution General Circulation Models (GCMs) is notoriously difficult due to the interaction of the complex topography and the Southern Hemisphere (SH) mid-latitude westerly winds. Therefore, methods of downscaling synoptic scale model data for New Zealand are useful to help understand past climate. New Zealand also has a wealth of palaeoclimate-proxy data to which the downscaled model output can be compared, and to provide a qualitative method of assessing the capability of GCMs to represent, in this case, the climate 6000 years ago in the Mid-Holocene. In this paper, a synoptic weather and climate regime classification system using Empirical Orthogonal Function (EOF) analysis of GCM and reanalysis data, was used. The climate regimes are associated with surface air temperature and precipitation anomalies over New Zealand. From the analysis in this study, we find that increased trough activity in summer and autumn led to increased precipitation, with an increased north-south pressure gradient ("zonal events") in winter and spring leading to drier conditions. Opposing effects of increased (decreased) temperature are also seen in spring (autumn) in the South Island, which are associated with the increased zonal (trough) events. Evidence from the palaeoclimate-proxy data suggests that the Mid-Holocene was characterized by increased westerly wind events in New Zealand, which agrees with the preference for trough and zonal regimes in the models.
First experimental evidence for the CO2-driven origin of Stromboli's major explosions
Authors: Aiuppa A. , Burton M. , Allard P. , Caltabiano T. , Giudice G. , Gurrieri S. , Liuzzo M. , Salerno G.
Published: April 2011

Abstract. We report on the first detection of CO2 flux precursors of the till now unforecastable larger than normal ("major") explosions that intermittently occur at Stromboli volcano (Italy). Automated survey of the crater plume emissions in the period 2006–2010, during which 12 such explosions happened, demonstrate that these events are systematically preceded by a brief phase of increasing CO2/SO2 weight ratio (up to >40) and CO2 flux (>1300 t/d) with respect to the time-averaged values of 3.7 and ~500 t/d typical for standard Stromboli's activity. These signals are best explained by the accumulation of CO2-rich gas at a discontinuity of the plumbing system (decreasing CO2 emission at the surface), followed by increasing gas leakage prior to the explosion. Our observations thus support the recent model of Allard (2010) for a CO2-rich gas trigger of recurrent major explosions at Stromboli, and demonstrate the possibility to forecast these events in advance from geochemical precursors. These observations and conclusions have clear implications for monitoring strategies at other open-vent basaltic volcanoes worldwide.
Antitumor Activity ofCitrus maxima(Burm.) Merr. Leaves in Ehrlich's Ascites Carcinoma Cell-Treated Mice
Authors: KunduSen Sriparna , Gupta Malaya , Mazumder Upal K. , Haldar Pallab K. , Saha Prerona , Bala Asis
Published: April 2011

Context. The plantCitrus maximaMerr. (Rutaceae), commonly known as shaddock or pomelo is indigenous to tropical parts of Asia. The objective of present study is to evaluate the methanol extract ofCitrus maximaleaves for its antitumor activity against Ehrlich's Ascites Carcinoma cell in Swiss albino mice.Experimental design. The antitumor activity of methanol extract ofCitrus maximaleaves (MECM) was evaluated against Ehrlich Ascites Carcinoma (EAC) cell line in Swiss albino mice. 2 × 106cells were inoculated in different groups of animals. MECM (200 and 400 mg/kg BW i.p.) was administered for nine consecutive days. On day 10th half the animals of different groups were sacrificed for determination of tumor and haematological parameters and the rest half were kept with sufficient food and water ad libitum for determination of increase in life span.Result and Discussions. Oral administration of the extract at the doses of 200 and 400 mg/kg significantly decreased tumor parameters such as tumor volume, viable tumor cell count and increased body weight, hematological parameters and life span in respect of the EAC control mice.Conclusion. Experimental design exhibits significant antitumor activity of the extract (MECM) in a dose dependant manner.
Social and environmental factors affecting fecal glucocorticoids in wild, female white‐faced capuchins (Cebus capucinus)
Authors: Carnegie Sarah D. , Fedigan Linda M. , Ziegler Toni E.
Published: April 2011

Assessing glucocorticoid levels in free‐ranging nonhuman primates provides a means to determine the social and environmental stress load for individuals. We investigated the effect of four proximate variables—reproductive state, season, male rank stability, and dominance rank—on the level of fecal glucocorticoids (cortisol metabolites) in eight adult female white‐faced capuchin monkeys in Costa Rica. Reproductive state, season, and male rank stability significantly affected fecal glucocorticoids while female dominance rank did not. Cortisol levels were significantly higher in pregnant females as compared with lactating or other reproductive states. Cortisol levels were higher among females during the dry season compared with the wet season, suggesting a metabolic adaptation to maintain homeostasis in drier, hotter conditions. Although unfamiliar males present a greater infanticidal threat than do familiar ones, we found that females experienced higher glucocorticoid levels during male rank instability events, regardless of whether the alpha male role was taken over by a familiar or an unfamiliar male. Our findings provide important benchmark and comparative data for future studies on the variables that affect glucocorticoid levels in this species and other mammals. Am. J. Primatol. 73:861–869, 2011. © 2011 Wiley‐Liss, Inc.
Dearomatization Strategies in the Synthesis of Complex Natural Products
Authors: Roche Stéphane P. , Porco John A.
Published: April 2011

Evolution in the field of the total synthesis of natural products has led to exciting developments over the last decade. Numerous chemoselective and enantioselective methodologies have emerged from total syntheses, resulting in efficient access to many important natural product targets. This Review highlights recent developments concerning dearomatization, a powerful strategy for the total synthesis of architecturally complex natural products wherein planar, aromatic scaffolds are converted to three‐dimensional molecular architectures.
The Price of a Piece of Cheese: Value from Fit Between Epistemic Needs and a Learning Versus an Outcome Focus
Authors: McNeill Ilona M. , Higgins E. Tory , De Dreu Carsten K. W. , Nijstad Bernard A.
Published: April 2011

In decision making, people can focus on decisional outcomes (outcome focus), but they can also focus on gaining knowledge about the decisional domain (learning focus). Furthermore, people differ in the strength of their epistemic needs—their preference for developing a rich and accurate understanding of the world. We invoke the regulatory fit theory to predict that higher epistemic needs better fit a learning focus than lower epistemic needs, resulting in a greater increase in valuation of the chosen option when a learning rather than an outcome focus is induced. This general hypothesis was tested and supported in three studies, each focusing on a different proxy to epistemic needs. Thus, individuals experienced greater value when they had lower expertise (Study 1), higher need for assessment (Study 2), and higher need for cognition (Study 3) when a learning rather than an outcome focus was induced. Implications for work on epistemic needs, regulatory fit theory, and decision‐making practice are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Determination of dipyridamole using TCPO–H2O2 chemiluminescence in the presence of silver nanoparticles
Authors: Wang Lijuan , Tang Yuhai
Published: April 2011

The method is based on the fact that dipyridamole can enhance the chemiluminescence (CL) emission from the redox reaction of bis (2,4,6‐tricholorophenyl) oxalate (TCPO) with H2O2 in the presence of silver nanoparticles (AgNPs). The CL reaction mechanism was discussed. The effect of concentrations of TCPO, H2O2, AgNPs and pH value on the CL reaction were investigated. Under the optimum conditions, the linear dynamic range was 1.0–1000 × 10−9 g/mL and the detection limit (3σ) was 9 × 10−10 g/mL. The relative standard deviation (RSD) was 4.8% for 1.0 × 10−9 g/mL dipyridamole (n = 7). The proposed method has been successfully applied to the determination of dipyridamole tablets and the recovery was 99–103%. Copyright © 2011 John Wiley & Sons, Ltd.
Insight into the Role of the Counteranion of an Imidazolium Salt in Organocatalysis: A Combined Experimental and Computational Study
Authors: Wei Siping , Wei Xi‐Guang , Su Xiaoyu , You Jingsong , Ren Yi
Published: April 2011

N‐Heterocyclic carbenes (NHCs) can serve as very reactive nucleophilic catalysts and exhibit strong basicity. Herein, we initiate a combined experimental and computational investigation of the NHC‐catalyzed ring‐closing reactions of 4‐(2‐formylphenoxy)but‐2‐enoate derivatives 1 to uncover the relationship between the counteranion of an azolium salt, the nucleophilicity and basicity of the carbene species, and the catalytic performance of the carbene species by taking imidazolium salts IPr⋅HX (X=counteranion, IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) as the representative precatalysts. The plausible mechanisms of IPr‐mediated ring‐closing reactions have been investigated by using DFT calculations. The hydrogen‐accepting ability, assigned as the basicity of the counteranion of IPr⋅HX and evaluated by DFT calculations, is correlated with the rate of deprotonation of C2 in IPr⋅HX, which could be monitored by the capture of the free carbene formed in situ with elemental sulfur. The deprotonation of C2 in IPr⋅HX with a more basic anion gives rise to a higher concentration of the free carbene and vice versa. At a relatively low concentration, IPr prefers to show a nucleophilic character to induce the intramolecular Stetter reaction. At a relatively high concentration, IPr primarily acts as a base to afford benzofuran derivatives. These data comprehensively disclose, for the first time, that the counteranions of azolium salts significantly influence not only the catalytic activity, but also possibly the reaction mechanism.
An Easy and Versatile Approach for the Regioselective De‐O‐benzylation of Protected Sugars Based on the I2/Et3SiH Combined System
Authors: Pastore Antonello , Valerio Silvia , Adinolfi Matteo , Iadonisi Alfonso
Published: April 2011

The use of cheap and easy to handle reagents, such as I2 and Et3SiH, at low temperature allows the regioselective removal of benzyl protecting groups from highly O‐benzylated carbohydrates. The observed regioselectivity is dependent on the nature of the precursor, the least accessible carbinol often being liberated. A mechanistic investigation reveals that in situ generated HI is the promoter of the process, whereas the regioselectivity appears to be mainly controlled by steric effects. However, the presence of an electron withdrawing acyl protecting group can switch the regioselectivity to favour deprotection of the carbinol position farthest from the ester group. The protocol is experimentally simple and provides straightforward access in useful yields to a wide range of partially protected mono‐ and disaccharide building blocks that are valuable for the synthesis of either biologically useful oligosaccharides or highly functionalised chiral compounds. Partially protected sugars thus obtained can also be coupled in situ with a glycosyl donor, as illustrated by the one‐pot synthesis of a Lewis X mimic from fully protected precursors.
Ferrocene‐Based Trimethylsilyl Chalcogenide Reagents for the Assembly of Functionalized Metal–Chalcogen Architectures
Authors: MacDonald Daniel G. , Eichhöfer Andreas , Campana Charles F. , Corrigan John F.
Published: April 2011

The ferrocene‐based trimethylsilyl chalcogenide reagents [FcC(O)OCH2CH2ESiMe3] (2, E=S, 3 E=Se, Fc=[Fe(η5‐C5H5)(η5‐C5H4)]) and [FcC(O)NHCH2CH2SSiMe3] (8b) have been synthesized. The reagents were reacted with solubilized transition‐metal acetates to yield functionalized complexes and clusters, including the spherical nanocluster [Ag14S{SCH2CH2O(O)CFc)}12(PPh3)6] (11, PPh3=triphenylphosphine). The complexes were characterized by NMR spectroscopy and X‐ray crystallography. The electrochemical behavior of the complexes was explored by cyclic voltammetry and each displayed a single quasi‐reversible redox wave with some adsorption to the electrode surface.
Heterogeneous Organocatalysis at Work: Functionalization of Hollow Periodic Mesoporous Organosilica Spheres with MacMillan Catalyst
Authors: Shi Jiao Yi , Wang Chang An , Li Zhi Jun , Wang Qiong , Zhang Yuan , Wang Wei
Published: April 2011

We report a new method for the synthesis of hollow‐structured phenylene‐bridged periodic mesoporous organosilica (PMO) spheres with a uniform particle size of 100–200 nm using α‐Fe2O3 as a hard template. Based on this method, the hollow‐structured phenylene PMO could be easily functionalized with MacMillan catalyst (H‐PhPMO‐Mac) by a co‐condensation process and a “click chemistry” post‐modification. The synthesized H‐PhPMO‐Mac catalyst has been found to exhibit high catalytic activity (98 % yield, 81 % enantiomeric excess (ee) for endo and 81 % ee for exo) in asymmetric Diels–Alder reactions with water as solvent. The catalyst could be reused for at least seven runs without a significant loss of catalytic activity. Our results have also indicated that hollow‐structured PMO spheres exhibit higher catalytic efficiency than solid (non‐hollow) PMO spheres, and that catalysts prepared by the co‐condensation process and “click chemistry” post‐modification exhibit higher catalytic efficiency than those prepared by a grafting method.
Viability of 4,5‐Dihydro‐1,2,3,4‐oxatriazoles Reinvestigated
Authors: Firdous Samia , Banert Klaus , Auer Alexander A.
Published: April 2011

The first procedures to prepare 4‐bromo‐4‐methylpentanal and 4‐azido‐4‐methylpentanal are reported. The latter compound and also the parent 4‐azidobutanal do not lead to 4,5‐dihydro‐1,2,3,4‐oxatriazoles by intramolecular 1,3‐dipolar cycloaddition, although it was claimed to be so in the literature. The NMR spectroscopic data of such heterocycles reported previously do not agree with those of similar substances and are incompatible with 13C NMR spectroscopic chemical shifts calculated by quantum chemical methods in the presented work. These calculations show furthermore that the intramolecular cycloaddition of 4‐azidobutanals to give the title compounds is strongly endothermic and thus most probably not possible.
Synthesis of (+)‐Dumetorine and Congeners by Using Flow Chemistry Technologies
Authors: Riva Elena , Rencurosi Anna , Gagliardi Stefania , Passarella Daniele , Martinelli Marisa
Published: April 2011

An efficient total synthesis of the natural alkaloid (+)‐dumetorine by using flow technology is described. The process entailed five separate steps starting from the enantiopure (S)‐2‐ (piperidin‐2‐yl)ethanol 4 with 29 % overall yield. Most of the reactions were carried out by exploiting solvent superheating and by using packed columns of immobilized reagents or scavengers to minimize handling. New protocols for performing classical reactions under continuous flow are disclosed: the ring‐closing metathesis reaction with a novel polyethylene glycol‐supported Hoveyda catalyst and the unprecedented flow deprotection/Eschweiler–Clarke methylation sequence. The new protocols developed for the synthesis of (+)‐dumetorine were applied to the synthesis of its simplified natural congeners (−)‐sedamine and (+)‐sedridine.
Evidence for a One‐Electron Mechanistic Regime in Dirhodium‐Catalyzed Intermolecular CH Amination
Authors: Kornecki Katherine P. , Berry John F.
Published: April 2011

Swift and energy efficient conversion of chemical feedstocks to pharmaceuticals and agrochemicals requires the development of new methods to add nitrogen functionality to unfunctionalized organic substrates. Dirhodium‐catalyzed insertion of nitrene species into CH bonds is a promising new method, the main drawback of which is the currently limited understanding of the catalytic mechanism. Herein, cyclic voltammetry and controlled potential electrolysis measurements have enabled us to solve many of the mechanistic mysteries of intermolecular CH amination catalyzed by [Rh2(esp)2] (esp=α,α,α′,α′‐tetramethyl‐1,3‐benzenedipropanoate). The primary result is that, in addition to a simple nitrene‐transfer mechanism that dominates the early stages of the reaction, another mechanism is available that relies on sequential proton‐coupled electron transfer steps. Whereas the nitrene‐transfer mechanism requires the use of expensive, atom‐inefficient oxidants, we show that simple one‐electron oxidants such as Ce4+ may be used to achieve catalytic CH amination via the one‐electron mechanistic regime.
Organocatalytic enantioselective Michael addition of malononitrile to nitroolefins catalyzed by bifunctional thiourea
Authors: Guo Hai‐Ming , Li Jian‐Guo , Qu Gui‐Rong , Zhang Xiao‐Mei , Yuan Wei‐Cheng
Published: April 2011

A novel enantioselective Michael addition of malononitrile to trans‐β‐nitroolefins in the presence of bifunctional amine thiourea organocatalyst is developed. The Michael reaction catalyzed by amine thioureas containing both central and axial chiral elements proceeded smoothly and provided the desired adducts with high yields (up to 96% yield) and moderate enantioselectivities (up to 83% enantiomeric excess). Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Comparison of Analytic and Sensoric Methods on Evaluation of the Performance according to Odor Reduction
Authors: Täffner Tim , Schlegelmilch Mirko , Kleeberg Kim , Schindler Sabrina , Genske Dieter , Krings Ulrich , Stegmann Rainer , Berger Ralf Günter , Niemeyer Bernd
Published: April 2011

Die Geruchsstoffe in der Prozessabluft eines kaffeeverarbeitenden Betriebes wurden mit einem Festbettadsorber im Pilotmaßstab vermindert. Zur Beurteilung der Reinigungsleistung verschiedener Adsorbentien wurden Durchbruchskurven mit Hilfe eines Flammenionisationsdetektors, elektronischer Nasen sowie der Olfaktometrie und analytischer Verfahren ermittelt. Die chemisch‐analytische Bestimmung der Geruchs‐ bzw. Schadstoffe erfolgte durch Anreicherung auf Tenax TA und auf SPME‐Fasern. Die Hauptgeruchsstoffe konnten identifiziert und das Adsorptionsverhalten der Adsorbentien charakterisiert werden. Die elektronischen Nasen wurden erstmals nach dem Prinzip eines Olfaktometers betrieben.
Potential to Optimize Scrubbers for Biogas Cleaning. Part 1 – Physical Scrubbers
Authors: Götz Manuel , Köppel Wolfgang , Reimert Rainer , Graf Frank
Published: April 2011

Die Anlagenanzahl zur Erzeugung und Aufbereitung von Biogas entsprechend den Anforderungen der DVGW‐Arbeitsblätter G 260 und G 262 nimmt zu. Die häufigsten zur Aufbereitung eingesetzten Technologien sind die Druckwechseladsorption und verschiedenartige Wäschen. Die Aufbereitungstechnologien werden bisher kaum an die standortspezifischen Parameter angepasst, sondern in ihrer Standardeinstellung betrieben. Am Beispiel der Druckwasser‐ und der Genosorb‐Wäsche werden die Einflüsse der Prozessparameter und Optimierungspotenziale aufgezeigt. Die Untersuchung erfolgte auf Basis von Messungen, unterstützt durch die Software Aspen Plus.
Enhanced Raman Scattering of Elliptical Laser beam in a Collisional Plasma
Authors: Singh A. , Walia K.
Published: April 2011

This paper presents the Enhanced Raman scattering of a elliptical laser beam in a collisional plasma. We have considered the mechanism of non‐uniform heating of carriers along the wave‐front, which is important in collisional plasma. The nonlinearity arising through non‐uniform heating leads to redistribution of carriers, which modifies the background plasma density profile in a direction transverse to pump beam axis. This modification in density effects the incident laser beam, plasma wave and back‐scattered beam. Non‐linear differential equations for the beam width parameters of pump laser beam, plasma wave and back‐scattered beam are set up and solved numerically. Numerical results predict the effect of self‐focusing of waves on the back‐scattered beam (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Erratum: Determination and Analysis of the Thermodynamic Regimes of Xenon Plasmas
Authors: Rodriguez R. , Gil J.M. , Florido R. , Rubiano J.G. , Mendoza M.A. , Martel P. , Minguez E.
Published: April 2011

This article has been published in the Early View section of www.cpp‐journal.org: 19 APR 2011 with the DOI number: 10.1002/ctpp.201000104 and is equal to the article: Determination and Analysis of the Thermodynamic Regimes of Xenon Plasmas (pages 863–876) R. Rodriguez, J.M. Gil, R. Florido, J.G. Rubiano, M.A. Mendoza, P. Martel, and E. Minguez published online: 29 SEP 2011 in Issue 9/2011 with the DOI 10.1002/ctpp.201000114 (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of statistical nature of electrical breakdown time delay in nitrogen at 6.6 mbar pressure in presence of positive ions and N(4S) atoms
Authors: Z̆ivanović E. N. , Pejović Momc̆ilo M. , Pejović Milić M. , N.T.  , Nes̆ić
Published: April 2011

On the basis of the mean value of electrical breakdown time delay $ \overline t_d $ and the standard deviation of electrical breakdown time delay σ dependence on the afterglow period τ, the mechanisms which dominantly influence to breakdown initiation in nitrogen were separated. It was shown that the positive ions formed in mutual collision of long‐lived metastable molecules have a dominant role in breakdown initiation for τ values up to 70 ms. The metastable molecules were derived from previous breakdown and discharge. In this case σ ≪ td and the total time delay td is approximately equal to formative time tf which decreases in value with the increase of overvoltage. When positive ions have a dominant role in the breakdown initiation the Gaussian distribution describes data of td ≈ tf very well. For τ > 1 s, N (4S) atoms formed in previous breakdown and discharge, have a dominant role in the breakdown initiation. Then, σ ≈$ \overline t_d $ and Laue's distribution, which is valid for statistical time delay ts, describes td data very well (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dust Self‐Organized Structures I. Role of Ion Drag and Ion Diffusion on Screened Grains
Authors: Tsytovich V. , Morfill G.
Published: April 2011

Self‐organized dust structures are investigated using a Gurevich‐Parker model for non‐linear dust screening. The non‐linear dust drag coefficients and non‐linear diffusion coefficients are calculated numerically as functions of nonlinear parameter for screening, dust density and ion flux drift velocity. Nonlinear ion dust drag inside the structures creates an electric field with potential well for ions at the structure center. The equilibrium dust structures confine both the dust grains and the plasma particles, have a finite size and have inside an enhanced dust and ion densities. The necessary conditions for existence of equilibrium dust structures are found. The equilibrium dust structures are determined by two global parameters related to the external plasma flux and to the power of ionization. The equilibrium exist only in a restricted phase space of these two parameters and depends on the the drag coefficient at the structure center. The equilibrium requirements are found using non‐linear drag coefficient calculated numerically. It is shown that this phase space area can be broad but it is systematically decreasing with an increase of the ionization rate. It is found that equilibrium exists for dust structures with large dust and ion density concentration at the center and that for these structures the ion diffusion is strongly suppressed by ion scattering on non‐linearly screened grains. The results of the theory can be used to interpret the recently observed compact dust structures in micro‐gravity experiments and can provide some recommendations for future micro‐gravity experiments in spherical chambers (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymers for Green C–C Couplings
Authors: Albéniz Ana C. , Carrera Nora
Published: April 2011

Cleaner and environmentally more friendly cross‐coupling reactions can be carried out by the use of polymers as supports. A lot of work has been devoted to attach palladium catalysts on polymers, so they can be easily separated from the reaction mixture and reused. An overview of the methods used for this purpose is given; they include the encapsulation of palladium complexes or palladium nanoparticles by polymers and the synthesis of polymeric ligands that coordinate to palladium. Polymer‐supported reagents are also important in making cross‐coupling reactions easier to work up and more sustainable. The use of polymer‐supported stannanes in the Stille reaction has a special advantage, because organotin derivatives that are used as reagents are toxic. When polymeric tin reagents are used, the separation of the byproducts from the target product is good and the tin‐containing byproducts can be recycled, thus tin waste is avoided. Examples of this application will also be discussed.
Palladium‐Catalyzed [3+2] Cycloaddition Reaction of (Diarylmethylene)cyclopropa[b]naphthalenes with Arynes: An Efficient Synthesis of 11‐(Diarylmethylene)‐11H‐benzo[b]fluorenes
Authors: Lin Ying , Wu Luling , Huang Xian
Published: April 2011

A Pd‐catalyzed [3+2] cycloaddition reaction of (diarylmethylene)cyclopropa[b]naphthalenes with arynes provided an efficient approach for the synthesis of 11‐(diarylmethylene)‐11H‐benzo[b]fluorenes with good to excellent yields under mild conditions.
Cinchona Alkaloid Catalyzed Enantioselective Chlorination of 3‐Aryloxindoles
Authors: Zhao Mei‐Xin , Zhang Zhi‐Wang , Chen Ming‐Xiao , Tang Wen‐Hao , Shi Min
Published: April 2011

O‐Benzoylquinidine is an effective organocatalyst for the asymmetric chlorination of 3‐aryloxindoles by using easily available N‐chlorosuccinimide (NCS) as chlorine source to give the corresponding 3‐aryl‐3‐chlorooxindoles in excellent yields and up to 93 % enantiomeric excess.
Four case studies in using expert opinion to inform priors
Authors: Kuhnert Petra M.
Published: April 2011

Priors gained from expert opinion can be the key to effective decision‐making. Yet, there is continuing controversy with its use because of its subjective and potentially biased nature. I examine the use of expert opinion through four environmental case studies in which one or more experts participated in an elicitation exercise to provide inference on ecological problems. In each case study, I examine how expert opinion informed the model and the potential pitfalls that could result, especially in data‐limited situations.

I discuss two opposing schools of thought: (1) experts provide a valuable source of information that can offer useful insights into a model and (2) expert priors are most times biased, leading to incorrect results and bad decisions. I show that expert opinion has a place in ecological analyses if carefully structured in a model. In situations in which data are limited or simply not available, steps can be taken to ensure its proper use and interpretation from models so decisions can be made urgently and updated when new data becomes available. Copyright © 2011 John Wiley & Sons, Ltd.
Hydrologic‐response‐driven sediment transport at a regional scale, process‐based simulation
Authors: Ran Qihua , Loague Keith , VanderKwaak Joel E.
Published: April 2011

Assessing hydrologically driven erosion at regional scales from a process‐based perspective presents a significant challenge. Most regional‐scale erosion assessments are based upon a simple steady‐state hydrology foundation. For this study, the sediment transport version of the physics‐based Integrated Hydrology Model (InHM), excited by synthetically generated rainfall, was employed to assess long‐term hydrologically driven erosion for a regional‐scale island boundary‐value problem. The spatiotemporal dynamics of runoff generation, erosion, and deposition are illustrated through saturation, water depth, velocity, and sediment concentration results. The simulations demonstrate that process‐based assessment for concept development is both feasible and tractable at regional spatial and human time scales. Copyright © 2011 John Wiley & Sons, Ltd.