bluuebunny/crossref_metadata_2025 huggingface dataset:
QuickSCAT observations of extreme wind events over the Mediterranean and Black Seas during 2000–2008
Authors: Chronis Themis , Papadopoulos V. , Nikolopoulos E. I.
Published: September 2010

A total of 9 years (2000–2008) of QuickSCAT hi‐resolution (12.5 × 12.5 km) surface wind observations are employed to identify seasonal means and extreme (gale‐force) events over the Mediterranean and Black Seas. The Gulf of Lyon and the Aegean Sea are the regions with the highest sustained wind magnitudes throughout the year. Conversely, the lowest winds are found over the Tyrrhenian, the northern Adriatic and the eastern Black Seas. During winter, the Gulf of Lyon and the Aegean portray mean wind magnitudes ranging from 7 to 11 m/s. During summer, the Aegean Sea portrays the highest wind magnitudes over the entire study area. The lowest wind magnitudes during summer are encountered over the Tyrrhenian, northern Adriatic, eastern Black and eastern Mediterranean Seas (3–6 m/s). From the entire (2000–2008) observations, each QuickSCAT observation exceeding 20 m/s is considered an extreme event. For all the registered extreme events during 2000–2008, we calculate (1) 2‐D maps of seasonal frequency occurrence and (2) the histograms of wind directions for ten sub‐regions encompassed in the study area (Gulf of Lyon, Balearic Sea, Ligurian Sea, Tyrrhenian Sea, North African coast, Adriatic Sea, Ionian Sea, Aegean Sea, Eastern Mediterranean and Black Seas). Results pertaining to the frequency occurrence show coincidence between high (low) seasonal mean and extreme event frequency occurrence for the areas such as the Gulf of Lyon and the Aegean Sea (Tyrrhenian/southeastern Black Seas). In addition, it is shown that for several cases (Gulf of Lyon, Aegean Sea) the dominant wind direction of extreme events substantially differentiates from the seasonal mean wind directions. Finally we investigate the linearity of extreme event occurrence in terms of mean wind speed climatology over the sub‐regions encompassing the study area. Copyright © 2010 Royal Meteorological Society
Enhancing the utility of daily GCM rainfall for crop yield prediction
Authors: Ines Amor V. M. , Hansen James W. , Robertson Andrew W.
Published: September 2010

Global climate models (GCMs) are promising for crop yield predictions because of their ability to simulate seasonal climate in advance of the growing season. However, their utility is limited by unrealistic time structure of daily rainfall and biases in rainfall frequency and intensity distributions. Crop growth is very sensitive to daily variations of rainfall; thus any mismatch in daily rainfall statistics could impact crop yield simulations. Here, we present an improved methodology to correct GCM rainfall biases and time structure mismatches for maize yield prediction in Katumani, Kenya. This includes GCM bias correction (BC), to correct over‐ or under‐predictions of rainfall frequency and intensity, and nesting corrected GCM information with a stochastic weather generator, to generate daily rainfall realizations conditioned on a given monthly target. Bias‐corrected daily GCM rainfall and generated rainfall realizations were used to evaluate crop response. Results showed that corrections of GCM rainfall frequency and intensity could improve crop yield prediction but yields remain under‐predicted. This is strongly attributed to the time structure mismatch in daily GCM rainfall leading to excessively long dry spells. To address this, we tested several ways of improving daily structure of GCM rainfall. First, we tested calibrating thresholds in BC but were found not very effective for improving dry spell lengths. Second, we tested BC‐stochastic disaggregation (BC‐DisAg) and appeared to simulate more realistic dry spell lengths using bias‐corrected GCM rainfall information (e.g., frequency, totals) as monthly targets. Using rainfall frequency alone to condition the weather generator removed biases in dry spell lengths, improved predicted yields, but under‐predicted yield variability. Combining rainfall frequency and totals, however, not only produced more realistic yield variability but also corrected under‐prediction of yields. We envisaged that the presented method would enhance the utility of daily GCM rainfall in crop yield prediction. Copyright © 2010 Royal Meteorological Society
Determination of polycyclic aromatic hydrocarbons in water by a novel mesoporous‐coated stainless steel wire microextraction combined with HPLC
Authors: Wang Xue‐Mei , Du Xin‐Zhen , Rao Hong‐Hong , Lu Xiao‐Quan
Published: September 2010

A novel mesoporous‐coated stainless steel wire microextraction coupled with the HPLC procedure for quantification of four polycyclic aromatic hydrocarbons in water has been developed, based on the sorption of target analytes on a selectively adsorptive fiber and subsequent desorption of analytes directly into HPLC. Phenyl‐functionalized mesoporous materials (Ph‐SBA‐15) were synthesized and coated on the surfaces of a stainless steel wire. Due to the high porosity and large surface area of the Ph‐SBA‐15, high extraction efficiency is expected. The influence of various parameters on polycyclic aromatic hydrocarbons extraction efficiency were thoroughly studied and optimized (such as the extraction temperature, the extraction time, the desorption time, the stirring rate and the ionic strength of samples). The results showed that each compound for the analysis of real water samples was tested under optimal conditions with the linearity ranging from 1.02×10−3 to 200 μg/ L and the detection limits were found from 0.32 to 2.44 ng/ L, respectively. The RSD of the new method was smaller than 4.10%.
A guide to guidelines for the treatment of PTSD and related conditions
Authors: Forbes David , Creamer Mark , Bisson Jonathan I. , Cohen Judith A. , Crow Bruce E. , Foa Edna B. , Friedman Mathew J. , Keane Terence M. , Kudler Harold S. , Ursano Robert J.
Published: September 2010

In recent years, several practice guidelines have appeared to inform clinical work in the assessment and treatment of posttraumatic stress disorder. Although there is a high level of consensus across these documents, there are also areas of apparent difference that may lead to confusion among those to whom the guidelines are targeted—providers, consumers, and purchasers of mental health services for people affected by trauma. The authors have been responsible for developing guidelines across three continents (North America, Europe, and Australia). The aim of this article is to examine the various guidelines and to compare and contrast their methodologies and recommendations to aid clinicians in making decisions about their use.
The increasing workload in head and neck surgery: An epidemiologic analysis
Authors: Bhattacharyya Neil
Published: September 2010

Objectives/Hypothesis:

Determine if there might be an increase in the workload for head and neck surgery based on an aging population.

Study Design:

Cross‐sectional analysis of a national database.

Methods:

The frequency of head and neck surgical procedures (HNSPs) performed in 2006 in the inpatient and outpatient settings in the United States were assessed using the National Hospital Discharge Summary and the National Survey of Ambulatory Surgery, respectively. From US Census Bureau statistics, age‐specific HNSP rates were determined and projected to the 2020 population based on census bureau predicted changes in population demographics. The surgical workload burden was assessed in 2006 and projected to 2020 based on the predicted changes in procedure rates and resource‐based relative value scale.

Results:

An estimated 366,050 HNSPs (142,397 inpatient vs. 223,653 outpatient) were performed in 2006 requiring a total of 2.49 million physician work relative value units (RVUs). With the expected changes in population demographics in 2020, an estimated 422,183 HNSPs will be performed (163,781 inpatient vs. 258,402 outpatient) requiring 2.88 million work RVUs in head and neck surgery. Both the HNSP rate and projected RVUs increase approximate 15.3%.

Conclusions:

Based on national health statistics and US census data we can anticipate a substantial increase in the workload for head and neck surgeons. Efforts should be directed at assessing manpower requirements in head and neck surgery based on the impact of an aging US population. Laryngoscope, 2011
Ultradrawing properties of ultrahigh‐ molecular‐weight polyethylene/carbon nanotube fibers prepared at various formation temperatures
Authors: Yeh Jen‐Taut , Lai Yu‐Ching , Liu Hai , Shu Yao‐Chi , Huang Chi‐Yuan , Huang Kuo‐Shien , Chen Kan‐Nan
Published: September 2010

The influence of formation temperature on the ultradrawing properties of ultrahigh‐molecular‐weight polyethylene/carbon nanotube (UHMWPE/CNT) fiber specimens is investigated. Gel solutions of UHMWPE/CNT with various CNT contents were gel‐spun at the optimum concentration and temperature but were cooled at varying formation temperatures in order to improve the ultradrawing and tensile properties of the UHMWPE/CNT composite fibers. The achievable draw ratio (Dra) values of UHMWPE/CNT as‐prepared fibers reach a maximum when they are prepared with the optimum CNT content and formation temperature. The Dra value of UHMWPE/CNT as‐prepared fibers produced using the optimum CNT content and formation temperature is about 33% higher than that of UHMWPE as‐prepared fibers produced using the optimum concentration and formation temperature. The percentage crystallinity (Wc) and melting temperature (Tm) of UHMWPE/CNT as‐prepared fiber specimens increase significantly as the formation temperature increases. In contrast, Wc increases but Tm decreases significantly as the CNT content increases. Dynamic mechanical analysis of UHMWPE and UHMWPE/CNT fiber specimens exhibits particularly high α‐transition and low β‐transition, wherein the peak temperatures of α‐transition and β‐transition increase dramatically as the formation temperature increases and/or CNT content decreases. In order to understand these interesting drawing, thermal and dynamic mechanical properties of the UHMWPE and UHMWPE/CNT as‐prepared fiber specimens, birefringence, morphological and tensile studies of as‐prepared and drawn fibers were carried out. Possible mechanisms accounting for these interesting properties are proposed. Copyright © 2010 Society of Chemical Industry
PMP® Certification as a Core Competency: Necessary but Not Sufficient
Authors: Starkweather Jo Ann , Stevenson Deborah H.
Published: September 2010

This research seeks to investigate the relationship between project management certification and established project management core competencies in the IT industry. This study was conducted in two phases, the objective being to first identify those characteristics most common to the successful hire of project managers, from the perspective of IT recruiters. Once identified, the study sought to determine preference for these characteristics from the point of view of corporate IT executives. Two hypotheses were tested in an effort to determine the valuation of Project Management Professional (PMP®) certification as a core competency and as an indicator of project success. Both hypotheses were rejected, as results indicated that PMP® certification was the least valued of 15 core competencies and that there was no difference in project success rates between PMP®-certified project managers and uncertified project managers. In addition, recruiters’ and IT executives’ suggestions for improvement in the delivery of the project management body of knowledge are discussed.
Single-Loop Project Controls: Reigning Paradigms or Straitjackets?
Authors: Abdel-Hamid Tarek K.
Published: September 2010

This article reports on the results from an ongoing research program to study the role mental models play in project decision making. Project management belongs to the class of multiloop nonlinear feedback systems, but most managers do not see it that way. Our experimental results suggest that managers adopt simplistic single-loop views of causality, ignore multiple feedback interactions, and are insensitive to nonlinearities. Specifically, the article examines single-loop models of project planning and control, discusses their limitations, and proposes tools to address them.
Medicine‐taking behaviour in schizophrenia – part 1
Authors: Feetam Celia L , Roberts Hannah
Published: September 2010

In this, the first of two articles, Celia Feetam and Hannah Roberts focus on factors contributing to poor medicine‐taking behaviour in schizophrenia and the consequences of this. The second article will consider treatment variables that may influence such behaviour and the interventions that have been proposed to improve medicine‐taking behaviour in those diagnosed with schizophrenia. These articles follow on from two articles published in Progress in 2009 on Medicine‐taking behaviour in depression.1,2. Copyright © 2010 Wiley Interface Ltd
Physical examinations of mental health service users
Authors: Vanezis Andrew Peter , Manns Dudley
Published: September 2010

The Royal College of Psychiatrists recommends that every psychiatric inpatient should have a thorough physical examination within 24 hours of admission. Here, the authors present their cross‐sectional audit to assess the timing and quality of physical examinations within an inner London inpatient mental health unit. Copyright © 2010 Wiley Interface Ltd
Agomelatine: more than just another antidepressant
Authors: Titmarsh Steve , Hale Anthony
Published: September 2010

Professor Anthony Hale, Consultant Psychiatrist and Professor of Psychiatry at the University of Kent, reviewed some recent trial data for agomelatine at a Servier Laboratories‐sponsored satellite meeting at the Latest Advances in Psychiatry Symposium IX held in London in March 2010. Professor Hale explained how his views about the drug and its place in therapy have changed as a result of the new data. Steve Titmarsh reports. Copyright © 2010 Wiley Interface Ltd
Synthesis and properties of di‐ and trinitrobenzyl substituted pyridine derivates
Authors: Frej Adrian , Goeschen Catrin , Näther Christian , Lüning Ulrich , Herges Rainer
Published: September 2010

A new method to obtain di‐ and trinitrobenzyl substituted pyridines is presented in this paper. By systematic variation of reaction parameters, the reaction conditions were optimized. The novel synthesis circumvents the commonly used nitration of benzyl pyridines, and thus avoids the nitration of the heterocycle which is a common side reaction. Furthermore, the starting materials for the synthesis of a variety of photochromic nitrobenzyl pyridines are easily accessible. The half‐lives of the phototautomers of several new di‐ and trinitrobenzyl‐substituted pyridines were determined. Copyright © 2010 John Wiley & Sons, Ltd.
Deformation induced evolution of mobility in PMMA
Authors: Lee Eun‐Woong , Medvedev Grigori A. , Caruthers James M.
Published: September 2010

The stress relaxation response in the glassy state just below Tg was measured for poly(methylmethacrylate) following application of constant strain rate uniaxial tensile deformation at various locations on the stress–strain curve, including the yield and post‐yield region. The macroscopic mobility was determined from analysis of the relaxation response. Up to a factor of 3 decrease in relaxation time was observed with the fastest relaxation occurring in the post‐yield softening region. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
How silanization of silica particles affects the adsorption of PDMS chains on its surface
Authors: Akoum Rami Al , Vaulot Cyril , Schwartz Dominique , Hirn Marie‐Paule , Haidar Bassel
Published: September 2010

A series of six fumed silica types, with different surface areas in the 50–400 m2/g range, were modified by grafting with trimethylchlorosilane. The grafting reaction was controlled by elemental analyses, surface hydroxyl titration, and combustion techniques. The silica surface energy was determined as a function of silanization degree by inverse gas chromatography (IGC). Adsorption of a series of poly(dimethylsiloxane) elastomers with molecular weights ranging between 4 and 420 kg/mol on silica was followed using flow microcalorimeter (FMC). IGC results show that free adsorption energies of two series of alkanes and siloxanes as well as the dispersive component of the surface energy were found to decrease monotonously with surface silanization and so does the polymer molar heat of adsorption. FMC results indicate, however, that the conformation of the macromolecules on silica depends on the silica surface area but remains unaffected by the surface treatments. A given polymer chain was found to remain adsorbed on the surface preserving its same conformation until its molar heat of adsorption falls bellow a critical value. These findings offer a better monitoring of surface–polymer interactions as it defined a comprehensive relationship between the degree of modifications of the filler surface and polymer adsorption conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Structure determination of a protein assembly by amino acid selective cross‐saturation
Authors: Kanamori Eiji , Igarashi Shunsuke , Osawa Masanori , Fukunishi Yoshifumi , Shimada Ichio , Nakamura Haruki
Published: September 2010

Amino acid selective cross‐saturation (ASCS) method not only provides information about the interface of a protein assembly by the spin relaxation experiment, but also identifies the amino acid residues in the acceptor protein, which are located close to the selectively labeled amino acid residues in the donor protein. Here, a new method was developed to build a precise structural model of a protein assembly, which satisfies the experimental ASCS values, using simulated annealing computation. This method was applied to the ubiquitin–yeast ubiquitin hydrolase 1 (Ub‐YUH1) complex to build a precise complex structure compatible with that determined by X‐ray crystallography. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Reverse biased electroluminescence spectroscopy of crystalline silicon solar cells with high spatial resolution
Authors: Schneemann Matthias , Helbig Anke , Kirchartz Thomas , Carius Reinhard , Rau Uwe
Published: September 2010

Electroluminescence spectra of different types of crystalline silicon solar cells obtained under reverse bias are analysed on a macroscopic as well as on a microscopic scale. The calibrated spectra of all samples exhibit a dominant peak at the band‐gap energy Eg ≈ 1.1 eV. Although the fraction of visible light may vary over one order of magnitude, the shapes of the calibrated spectra are qualitatively similar. Single emission sites have been investigated with respect to the externally applied voltage V and their onset voltage VO by a microscope attached to a spectrometer. While the fraction of visible light within the spectra of individual sites increases with higher absolute onset voltage VO of the respective site, the actual applied voltage V has no influence on the shape of the spectra. Furthermore, we find that the emission intensity of all investigated single sites increases linearly with the applied voltage V. A nonlinear increase of local emission intensities as reported in the literature results from consecutive appearance of distinct breakdown sites in close distance to each other. Such series of breakdown events are not resolved without using microscopic measurements and therefore mistaken as the illumination intensity of a single site.
Optical spectroscopy of bilayer graphene
Authors: Geng Baisong , Horng Jason , Zhang Yuanbo , Tang Tsung‐Ta , Park Cheol‐Hwan , Girit Caglar , Hao Zhao , Martin Michael , Zettl Alex , Crommie Michael , Louie Steven , Wang Feng
Published: September 2010

Infrared spectroscopy reveals unusual tunable electronic structure and optical behaviour in electrically gated bilayer graphene. In a dual‐gate bilayer graphene device, we were able to control the carrier doping and a semiconductor bandgap independently by using different combinations of the top and bottom gate voltages. The field‐induced bandgap can be probed directly through the emerging interband transitions in infrared absorption spectra. A tunable bandgap up to 250 meV has been observed in our dual‐gate bilayer graphene devices. This unique tunable bandgap can lead to many new physical phenomena. One example is an unusual phonon–exciton Fano resonance when the electronic bandgap is tuned to match the phonon vibration energy. Here (continuous) electron–hole transitions and (discrete) phonon vibrations form a coupled system described by the Fano resonance, and the infrared absorption spectra exhibit characteristic quantum interference between the phonon and exciton transitions. Remarkably, this coupled phonon–exciton Fano resonance can be continuously tuned through electrical gating in bilayer graphene, and its behaviour is described quantitatively by theory.
Revealing new electronic behaviours in the Raman spectra of chirality‐enriched carbon nanotube ensembles
Authors: Duque Juan G. , Chen Hang , Swan Anna K. , Hároz Erik H. , Kono Junichiro , Tu Xiaomin , Zheng Ming , Doorn Stephen K.
Published: September 2010

We present Raman spectroscopy of single‐walled carbon nanotubes (SWNTs) that are enriched in metallic species by density gradient ultracentrifugation (DGU) and enriched in single semiconducting chiralities through DNA‐based separations. Radial breathing mode (RBM) spectra demonstrate that DGU samples are highly enriched in armchair chiralities. The enrichment allows acquisition of pure G‐band spectra of the armchair SWNTs and reveals that the LO mode is absent in these structures. Raman excitation profiles for the G‐band in nearly pure (10,2) samples reveals a strong asymmetry in the intensities of the resonance coupling to incident and scattered photons. The experimental data may be fit using a four‐level molecular model for Raman scattering and the strong asymmetry can be understood as a consequence of the presence of non‐Condon effects. The result requires a reassessment of the assumption that the incident and scattered resonances are equivalent. The consequences of such non‐Condon effects on other SWNT electronic and optical processes will be an important topic for future study.
Effects of Hypericum perforatum extract on diabetes‐induced learning and memory impairment in rats
Authors: Hasanein Parisa , Shahidi Siamak
Published: September 2010

Cognitive impairment occurs in diabetes mellitus. Hypericum perforatum has been used in folk medicine to improve mental performance. Here it is hypothesized that chronic treatment with an extract of Hypericum perforatum (6, 12 and 25 mg/kg, p.o.) would have effects on passive avoidance learning (PAL) and memory in control and streptozotocin‐induced diabetic rats. Treatments were begun at the onset of hyperglycaemia. PAL was assessed 30 days later. A retention test was done 24 h after training. At the end, the animals were weighed and blood samples were drawn for plasma glucose measurement. Diabetes caused impairment in acquisition and retrieval processes of PAL and memory. Hypericum treatment (12 and 25 mg/kg) improved learning and memory in control rats and reversed learning and memory deficits in diabetic rats. A dose of 6 mg/kg did not affect cognitive function. Hypericum administration did not alter the body weight and plasma glucose levels. Antioxidant properties and cholinergic facilitatory effects of Hypericum may be involved in its nootropic effects. These results show that Hypericum perforatum prevented the deleterious effects of diabetes on PAL and memory. As Hypericum would be free of major side effects compared with other nootropic medications, it may provide a new potential alternative for demented diabetic patients. Copyright © 2010 John Wiley & Sons, Ltd.
Rhodium(I)‐centered cyclotriveratrylene
Authors: Coolen H. K. A. C. , Reek J. N. H. , Ernsting J. M. , van Leeuwen P. W. N. M. , Nolte R. J. M.
Published: September 2010

The rigid bowl‐shaped molecule cyclotriveratrylene (CTV,1) was provided with short and long spacer arms terminating in triphenyl phosphite functions. These CTV ligands were used to immobilize a rhodium(I)‐carbonyl‐hydride complex. The ligand with short spacers gave a rigid, strained complex with a trigonal‐coordination sphere around the rhodium. The ligand with long flexible spacers allowed the formation of a large cavity after the complexation to the rhodium center. This cavity, however, is filled up by the spacer arms, as was indicated by NMR studies. Variable‐temperature NMR experiments suggested that the H‐Rh‐CO dipole in the rhodium‐ CTV complex can adopt two orientations: one with the hydride group pointing away from the CTV cavity (low‐temperature conformation) and one in which this orientation is inverted (high‐temperature conformation).
The influence of substituents on the geometry of the cyclopropane ring VIII. The molecular and crystal structures of azocyclopropane N,N′‐dioxide and 1,1′‐dimethylazocyclopropane N,N′‐dioxide
Authors: de Boer J. S. A. M. , Schenk H.
Published: September 2010

Crystals of azocyclopropane N,N′‐dioxide, (C3H5NO)2, (1) are monoclinic, space group C2/c, a = 8.708(2), b = 8.321(1), c = 9.836(2) Å, β = 95.437(3)° (243K). Z = 4. The final R for 479 independent observed reflections is 0.035. The molecules are centrosymmetric and have the bisecting (s‐cis) conformation for the NO group.

Crystals of 1,1′‐dimethylazocyclopropane N,N′‐dioxide, (C4H7NO)2, (2) are monoclinic, space group P21/n, a = 10.727(5), b = 7.181(3), c = 5.969(2) Å, β = 90.52 (2)° (223K), Z = 2. The final R for 773 independent observed reflections is 0.046. The molecules are also centrosymmetric but steric interference by the methyl group at C1 prevents them from assuming the bisecting conformation. The effect of the N(O)N(R) group on the geometry of the cyclopropane ring is small to negligeable.
Complex formation of Ca2+ ions with 1‐O‐n‐octyl‐β‐D‐mannofuranoside
Authors: Kooreman Peter A. , Engberts Jan B. F. N.
Published: September 2010

This paper describes the first example of complex formation of an alkylglycoside with calcium ions. Qualitative evidence for complex formation is obtained by titration microcalorimetry.
Effect of the nitrogen heteroatom on the photophysics and photochemistry of trans‐1‐styrylnaphthalene and trans‐9‐styrylphenanthrene in different solvents
Authors: Bartocci Giampiero , Mazzucato Ugo , Spalletti Anna
Published: September 2010

The effect of the nitrogen heteroatom on the excited state properties of trans‐1‐styryl‐naphthalene (1‐StN) and trans‐9‐styrylphenanthrene (9‐StPh) has been investigated by fluorimetric and photochemical techniques. The relaxation processes of two aza analogues of each of these diarylethylenes, bearing the nitrogen atom in the mono‐ and polycyclic aryl group, respectively, were studied in different solvents and over a large temperature range. The aza derivatives have smaller radiative and large reactive decay yields compared with the parent hydrocarbons. The polar solvent reduces the torsional energy barrier and favours the trans → cis photoisomerization while intramolecular hydrogen bonding may slow down the rate of the reactive deactivation.
The influence of the chiral environment in the photosynthesis of enantiomerically enriched hexahelicene. A sudden change in the chirality of hexahelicene by a change in the temperature of a chiral crystalline medium
Authors: Prinsen W. J. C. , Laarhoven W. H.
Published: September 2010

The enrichment of one of the enantiomers (P or M) of hexahelicene (3) synthesized by the photochemical cyclodehydrogenation of 2‐styryl‐benzo[c]phenanthrene (1) in chiral media has been (re)investigated. Four different chiral solvents, two cholesteric liquid crystals, two chiral crystals, all at several temperatures, and two chiral polymers were used as media. To avoid erroneous values from circular‐dichroism (CD) measurements due to contributions of chiral side‐products, the enantiomeric excess (ee) was determined by HPLC analysis.

In general the observed ee is small (< 7%). In chiral solvents the ee increases with decreasing temperatures. In the liquid crystals the macroscopic helix of the cholesteric phase has a small but distinct effect on the ee, probably due to the preferred fitting of one enantiomer of Z‐1 to the helix of the ‘solvent’. In chiral crystals the ee is relatively larger. A peculiar effect is observed when 1 is irradiated in ethyl (S)‐(+)‐O‐(4‐phenylbenzoyl)lactate. Below −19°C the M enantiomer and above −14°C the P enantiomer of 3 is the preferred photoproduct. In the polymer triacetylcellulose, M‐hexahelicene is formed in 4.5% excess; in β‐cyclodextrine only a very small amount of 3 is formed, due to the preferred photo‐isomerization into E‐1.
Synthesis and photochemistry of 2‐styrylpyrroles. Intermolecular photoaddition of pyrroles to a double bond
Authors: Šindler‐Kulyk Marija , Tomšić Slavica , Marinić ŽEljko , Metelko Biserka
Published: September 2010

Irradiation of the 2‐styrylpyrroles 3 and 5 resulted in intermolecular addition of the pyrrole derivative to the double bond of a second molecule in a regiospecific way to give the dimeric products 6 and 7 as the main products. The N‐methyl‐substituted derivative 4 did not show the same reaction, but reacts as the corresponding furan derivative.
Factors influencing the reaction‐mode selectivity and regiochemistry of intermolecular photocycloaddition reactions of ethenes to polysubstituted benzenes
Authors: Al‐Qaradawi S. , Gilbert A. , Jones D. T.
Published: September 2010

The photoreactions of the methylbenzonitriles; 2,3‐, 2,4‐, 2,6‐, 3,4‐, and 3,5‐ benzonitriles; and 2′‐ and 4′‐ methoxyacetophenones with cyclopentene and ethyl vinyl ether have been investigated. Meta photocycloaddition is the major process for the benzonitriles with cyclopentene, and regiochemical features reflect the influence of polar factors along the reaction pathway. The enol ether yields ortho cycloadducts exclusively from all the benzenoid derivatives. The thermal ring opening of the primary photoadduct and the photolability of the cycloocta‐1,3,5‐triene isomer depend markedly on the position of the substituents.
[2 + 2] Photoaddition of 2‐aminopropenenitriles to diarylethanediones. A product study
Authors: Döpp Dietrich , Fischer Michael‐Alexander
Published: September 2010

A selection of symmetrical (1a‐f) and unsymmetrical (4a,b) diarylethanediones, starting from their 3(n, π*) states, undergoes smooth head‐to‐head [2 + 2] photoaddition of various 2‐aminopropenenitriles 2A‐F to form oxetanes 3, 5 and 6 in moderate to good yields. Only one diastereomer out of two a‐priori possible regioisomers is formed in each case. The connectivity and the preferred geometry of the products is rationalized in terms of the geometry of the most easily accessible and most stabilized (including captodative stabilization) 1,4‐biradical intermediate. Whereas 2‐naphthyl‐substituted diones 1f and 4b form oxetanes, 1,1′‐naphthil and 1‐(1‐naphthyl)‐2‐phenylethanedione are ineffective.
Photoinduced energy‐ and electron‐transfer processes in dinuclear ruthenium(II) and/or osmium(II) complexes connected by a linear rigid bis‐chelating bridge
Authors: de Cola Luisa , Balzani Vincenzo , Barigelletti Francesco , Flamigni Lucia , Belser Peter , Bernhard Stefan
Published: September 2010

A rigid and linear bridging ligand containing two 4,5‐diazafluorene chelating units separated by an adamantane spacer (diazf‐a‐diazf) has been synthesized and its dinuclear complexes [(bpy)2Ru(diazf‐a‐diazf)Ru(bpy)2]4+ (RuII · FAF · RuII), [(bpy)2Os(diazf‐a‐diazf)Os(bpy)2]4+ (OsII · FAF · OsII), and [(bpy)2Ru(diazf‐a‐diazf)Os(bpy)2]4+ (RuII · FAF · OsII) have been prepared as PF−6 salts. In these novel compounds, each Ru‐based and Os‐based unit displays its own absorption spectrum and electrochemical properties, regardless of the presence of a second metal‐based unit. The luminescence properties have also been investigated and it has been shown that electronic energy transfer takes place in the mixed‐metal RuII · FAF · OsII species at 77K from the Ru‐based to the Os‐based unit with rate constant 2.6 · 108 s−1. At room temperature the intrinsic decay of the Ru‐based unit is too fast (3.3 · 109 s−1) to allow the occurrence of energy transfer. Partial oxidation of the binuclear compounds RuII · FAF · OsII and OsII · FAF · OsII by CeIV in acetonitrile‐water solutions leads to the mixed‐valence RuII · FAF · OsIII and OsII · FAF · OsIII species where the oxidized metal‐based unit quenches, by electron transfer, the luminescent excited state of the unit that is not oxidized. At room temperature, the rate constants for the excited state * RuII · FAF · OsIII · RuIII · FAF · OsII and * OsII FAF · OsIII · OsIII · FAF · OsII processes are 8.3 · 108 s−1 and 3.9 · 108 s−1, respectively, and the rate constant for the back‐electron‐transfer process RuIII · FAF · OsII · RuII · FAF · OsIII is 2.9 · 107 s−1.
Volume changes associated with intramolecular electron transfer during MLCT state formation. Time‐resolved optoacoustic studies of ruthenium cyano complexes
Authors: Jiwan Jean‐Louis Habib , Wegewijs Bas , Indelli Maria T. , Scandola Franco , Braslavsky Silvia E.
Published: September 2010

Volume changes associated with the intramolecular photooxidation of RuIIin bipyridine cyano complexes in aqueous solutions were determined by temperature‐dependent laser‐induced optoacoustics. The values obtained are attributed mainly to photoinduced changes in the specific interactions between the complexes and the water molecules of the first solvation shell. In particular, the values determined for the formation of the MLCT state in the homologous series Ru(bpy)(CN)2−4, Ru(bpy)(CN)3(CNCH3)−; and Ru(bpy)(CN)2(CNCH3)2, which are expansions for the two first compounds(i.e., ΔVR= 15, 10, andca.0 ml/mol, respectively), correlate directly with the number of cyanide ligands available for donor‐acceptor interactions with water. A parallel correlation with the number of cyanide ligands is found for the solvent effect on the MLCT energy of the complexes, as measured from the slope of plots of emission energyusthe solvent acceptor number. This correlation supports the concept of solvent (water in this case) reorganization around the MLCT state being responsible for the volume changes observed.
Medium effects on the photophysical properties of porphyrazine‐metal(II) complexes in micellar solutions
Authors: Dürr Heinz , Hayo Rudolf , David Elke , Willner Itamar , Zahavy Eran
Published: September 2010

The solubility of different phthalocyanine and porphyrazine metal(II) complexes 1–6 is described in cationic, neutral and anionic surfactants under various conditions. Optimal conditions were evaluated and photophysical properties of the dyes were measured. Various possibilities which have a direct effect on the aggregation phenomena were tested and dimerization constants and extinction coefficients are derived for the optimal monomer conditions. Each study was carried out in cationic, neutral and anionic micelles. With light‐scattering experiments micellar shapes were measured and compared with theoretical models. Triplet‐absorption spectra of the porphyrazine 2–4 were recorded and showed similar maxima to phthalocyanine 1. In steady‐state experiments photoinduced electron transfer reactions of 1, 2, 5 and 6 were investigated for several electron acceptors and hydrogen was evolved from 1, 3, 5 and 6 in a four‐component sacrificial system in order to check the photocatalytic properties of hydrophobic porphyrazines dissolved in surfactants.
Synthesis of a novel tetrapyrrolic macrolactam and its activity towards Uro'gen III synthase
Authors: Pichon Clotilde , Scott A. Ian
Published: September 2010

A novel macrocyclic tetrapyrrolelactam 8, analog of a putative intermediate, has been synthesized. Its very low inhibitory effect on Uro'gen III synthase renders it unlikely to be a low‐energy transition‐state analog.
Screening of arylboronic acids to search for a strong inhibitor for γ‐glutamyl transpeptidase (γ‐GTP)
Authors: Suenaga Hikaru , Nakashima Kazuaki , Mikami Masafumi , Yamamoto Hiromasa , James Tony D. , Sandanayake K. R. A. Samankumara , Shinkai Seiji
Published: September 2010

In a study of the development of a strong inhibitor for γ‐glutamyl transpeptidase (γ‐GTP), the inhibitory effect of 21 arylboronic acids was determined in the γ‐GTP‐mediated hydrolysis of N‐(L‐γ‐glutamyl)‐4‐nitroanilide. It was shown that most boronic acids can moderately inhibit the enzyme activity and, in particular, the inhibitory effects of (3‐formylphenyl)boronic acid and (3‐carboxyphenyl)boronic acid (9% and 12%, respectively) are comparable to that reported for the binary L‐serine‐plus‐borate inhibition system (7%). Furthermore, it was shown that the addition of physiologically nontoxic saccharides is very effective in regenerating the enzyme activity. This effect is attributed to the competitive binding of saccharides with the boronic acid inhibitor to pull it out into the water phase. Thus, this paper offers a novel methodology for inhibition and control of γ‐GTP activity.
Studies with plant‐cell cultures of the Chinese herbal plant, Tripterygium wilfordii. Isolation and characterization of diterpenes
Authors: Kutney James P. , Han Kang
Published: September 2010

A detailed analysis of the established cell‐culture line (coded as TRP4a) of the important Chinese herbal plant, Tripterygium wilfordii, in terms of diterpene production, is presented. In this study, 28 diterpenes have been isolated and characterized. Of these, 26 were isolated for the first time from the TRP4a cell line, 8 were novel compounds. From an analysis of the diterpenes obtained, a biosynthetic pathway of the pharmacologically interesting triepoxide, tripdiolide 29, is proposed.
Metallation and functionalization of 1‐allenylpyrrole
Authors: Tarasova O.A. , Taherirastgar F. , Verkruijsse H.D. , Mal'kina A.G. , Brandsma L. , Trofimov B.A.
Published: September 2010

1‐Allenylpyrrole is lithiated at the α‐carbon atom of the allenyl group by n‐butyllithium in mixtures of diethyl‐ether/hexane or tetrahydrofuran/hexane. Whereas functionalization with trimethylchlorosilane, butyl iodide and dimethyl disulfide gives only allenic derivatives, addition of carbonyl compounds generally leads to mixtures of allenic and acetylenic derivatives. Upon heating its solutions in ether or tetrahydrofuran, Li‐allenylpyrrole is slowly transformed into the lithium derivative of 1‐(propyn‐2‐yl)pyrrole.
Reductive O‐ and N‐alkylations. Alternative catalytic methods to nucleophilic substitution
Authors: Fache Fabienne , Bethmont Valérie , Jacquot Laurent , Lemaire Marc
Published: September 2010

Different amides have been selectively mono‐N‐alkylated using catalytic heterogeneous palladium and carbonyl compounds as alkylating agents. The same salt free method has been applied to the synthesis of ethers from alcohols. Reaction parameters have been studied in detail and a mechanism is proposed.
“Green” MMA; an environmentally benign and economically attractive process for the production of methyl methacrylate
Authors: Keijsper J. , Arnoldy P. , Doyle M.J. , Drent E.
Published: September 2010

Over the last seven years Shell has developed a novel, economically attractive, and environmentally benign process for the production of methyl methacrylate (MMA). The process is based on the highly efficient Palladium‐catalysed methoxycarbonylation of propyne (methyl‐acetylene or MA) under mild, non‐corrosive reaction conditions (temperature ca. 50°C, CO pressure ca. 10 bar) according to the equation:

MeOH + CO + HC ≡ C − Me(MA) → H2C = C(Me) − C(O)OMe(MMA)

The activity (> 20000 mol‐MMA/mol‐Pd.h) and selectivity (> 99%mol) of the homogeneous Pd catalyst are very high making a once‐through process with minimal waste possible.

The MA feedstock for the process, together with propadiene (PD), is separated from a steam‐cracker C3 stream by extractive distillation with DMF. Subsequently, PD is removed from this MA + PD/DMF mixture and isomerized over a heterogeneous K2O/Al2O3 catalyst to yield additional MA.

Crude MMA obtained from the methoxycarbonylation of MA can easily be purified by a ‘topping and tailing’ procedure to yield MMA of very high purity (> 99.99 w%).

This article describes some of the R&D work carried out at the ‘Koninklijke/Shell‐Laboratorium, Amsterdam’ which has enabled the design of a plant, based on this novel technology.
The use of dialkyl carbonates for safe and highly selective alkylations of methylene‐active compounds. A process without waste production
Authors: Bomben Andrea , Selva Maurizio , Tundo Pietro
Published: September 2010

The non‐toxic compound dimethyl carbonate (DMC) can be used as a methylating and a methoxycarbonylating agent in place of methyl chloride and phosgene, respectively. We report here that DMC and other dialkyl carbonates (DAlkCs: dimethyl, diethyl and dibenzyl carbonates) allow very selective alkylations of a variety of CH2‐acidic compounds. Both arylacetonitriles and alkyl arylacetates react with DAlkCs to yield the mono‐C‐alkylated derivatives (α‐alkyl‐α‐arylacetonitriles and alkyl α‐alkyl‐α‐arylacetates) with a selectivity of up to 99%, at complete conversion. Likewise, the mono‐C‐methylation by DMC proceeds selectively also on (aryloxy)acetonitriles and methyl (aryloxy)acetates. The reactions are carried out at temperature of 180‐220°C in the presence of weak bases (usually K2CO3); under such conditions, DAlkCs efficiently replace the common and very toxic alkylating agents (dialkyl sulfates and alkyl halides). In addition to the high selectivity obtained and the intrinsic safety of the dialkyl carbonates, the reported reactions give rise to neither organic nor inorganic waste products.
Palladium arenethiolates with intramolecularly coordinating nitrogen lewis bases
Authors: Janssen Maurits D. , Grove David M. , van Koten Gerard , Spek Anthony L.
Published: September 2010

The reaction of [PdCl2(MeCN)2] with one or two equivalents of Me3SiSC6H4NMe2‐2 in toluene affords the mono(arenethiolate) complex [PdCl(SC6H4NMe2‐2)] (1) or the bis(arenethiolate) complex [Pd(SC6H4NMe2‐2)2] (2), respectively, in high yields. [PdCl(SC6H4NMe2‐2)] (1) exists as a tetramer in the solid state (X‐ray) while [Pd(SC6H4NMe2‐2)2] (2) is a monomer both in the solid state and in solution (cryoscopy, NMR). The X‐ray structure determination of tetrameric 1 shows arenethiolate ligands bridging between PdCl units to form a unique eight‐membered U‐shaped Pd4S4 ring. Crystals of 1 are tetragonal, space group magnified image, with a = b = 12.0495(10) Å, c = 16.672(1) Å, V= 2420.6(3) Å3, Z = 2, and final R = 0.029, wR = 0.034 and S = 1.42 for 1174 reflections with I > 2.5 σ(I) and 111 variables. The X‐ray structure determination of 2 shows it to be monomeric in the solid state. The palladium has a square‐planar geometry that results from coordination by two S,N‐chelating arenethiolate ligands with a trans S and trans N arrangement of the donor atoms. Crystals of 2 are triclinic, space group magnified image, with a = 8.9923(5) Å, b = 9.2472(5) Å, c = 11.5933(6) Å, V = 825.93(9) Å3, Z = 2, and final R = 0.025, wR = 0.047 and S = 0.53 for 3603 reflections with I > 2.5 σ(I) and 226 variables.
Sulfonation oftrans‐10b,10c‐dimethyl‐10b,10c‐dihydropyrene and its 2,7‐di‐tert‐butyl derivative with sulfur trioxide
Authors: Cerfontain Hans , Koeberg‐Telder Ankie , Mitchell Reginald H. , Khalifa Nasr , Tashiro Masashi
Published: September 2010

The sulfodeprotonation oftrans‐10b,10c‐dimethyl‐10b,10c‐dihydropyrene (1) with sulfur trioxide has been studied in dioxane as solvent, as well as in dichloromethane, using 4.0–5.0 equivalents of dioxane relative to the amount of SO3as reactivity moderator. Reaction of1with 0.6 mol‐equiv. of SO3in dioxane at 22°C yields initially only the 2‐ and 4‐sulfonic acid in a 84/16 ratio. Using 3.0‐6.0 mol‐equiv. of SO3in dichloromethane with the temperature increasing from −78 up to 22°C the initially very rapid formation of the 1‐, 2‐ and 4‐sulfonic acid (formed in a ratio of 11/82/7) is followed by a much slower conversion into a mixture of 1,7‐, 2,4‐, 2,5‐ and 2,7‐disulfonic acid. These four acids are subsequently converted even more slowly into a mixture of the 1,4,7‐, 2,4,7‐ and 2,5,9‐trisulfonic acids to yield in part the 1,4,7,9‐, 2,4,7,9‐ and 2,4,7,10‐tetrasulfonic acids.trans‐2,7‐Di‐tert‐butyl‐10b, 10c‐dimethyl‐10b, 10c‐dihydropyrene (2) with 0.8–2.0 equiv. of SO3in dioxane as solvent gives the 4‐sulfonic acid which is slowly converted into a 16/84 mixture of the 4,9‐ and 4,10‐disulfonic acids.

The observed distributions of sulfonic acid isomers are discussed in terms of the directing effects of the “ideal” ‐ almost planar ‐ [14] annulene and the sulfo and/ortert‐butyl substituent(s) already present.
A new mechanistic model for hydride transfer related to the redox couple NADH/NAD+. Criticism on the quantum‐chemical MO approach
Authors: Buck H.M.
Published: September 2010

A mechanistic study of hydride transfer based on (simplified) NADH/NAD+ model systems is given. The new model originates from a classical mechanism generally indicated as being an intramolecular nucleophilic displacement reaction. There is some controversy with the results of quantum‐chemical calculations.
The CuA site of cytochrome c oxidase
Authors: Dennison Christopher , Canters Gerard W.
Published: September 2010

The recent exciting developments concerning the structure and function of the CuA site in cytochrome c oxidase (COX) and nitrous oxide reductase are reviewed. The XRD structures of a mitochondrial and a bacterial COX have been reported in 1995. In COX, the CuA centre is located in subunit II and is involved in electron transfer from a cytochrome c donor to the oxygen binding centre of the protein. The structural studies on the enzyme have revealed the coordination geometries of the many metal centres of COX, including the CuA site. A combination of spectroscopic and mutagenesis studies on the CuA centre led to the correct prediction of the structure of this unique copper centre. The construction of a CuA site in type 1 blue copper proteins is briefly discussed.
Aggregates of calix[4]arenes based on the 2,6‐diaminotriazine · imide system
Authors: Vreekamp Remko H. , Verboom Willem , Reinhoudt David N.
Published: September 2010

The synthesis of several calix[4]arenes functionalized with uracil or diaminotriazine moieties is described. The association between these complementary calix[4]arenes is strongly influenced by processes related to the position and directionality of the hydrogen‐bonding moieties. In the case of bis(uracil)calix[4]arene (4), self‐association is observed (K = 3.4 · 103 M−1 in CDCl3) whereas, in the case of bis(diamidotriazine)calix[4]arene (16), it was concluded from 1H‐NMR studies that intermolecular association is hampered by the formation of intramolecular hydrogen bonds. Due to the divergent orientation of the hydrogen‐bonding groups of bis(diaminotriazine)calix[4]arene (15b), it forms hydrogen‐bonded strands through interaction with 5‐ethyl‐5‐phenylbarbituric acid (17), resulting in the formation of a gel in chloroform.