bluuebunny/crossref_metadata_2025 huggingface dataset:
Axonal tracing of the normal and regenerating visual pathway of mouse, rat, frog, and fish using manganese‐enhanced MRI (MEMRI)
Authors: Sandvig Axel , Sandvig Ioanna , Berry Martin , Olsen Øystein , Pedersen Tina Bugge , Brekken Christian , Thuen Marte
Published: July 2011

Purpose:

To assess optic nerve (ON) regeneration after injury by applying manganese‐enhanced MRI (MEMRI) in a study of comparative physiology between nonregenerating rat and mouse species and regenerating frog and fish species.

Materials and Methods:

The normal visual projections of rats, mice, frogs, and fish was visualized by intravitreal MnCl2 injection followed by MRI. Rats and mice with ON crush (ONC) were divided into nonregenerating (ONC only), and regenerating animals with peripheral nerve graft (ONC+PNG; rats) or lens injury (ONC+LI; mice) and monitored by MEMRI at 1 and 20 days post‐lesion (dpl). Frog and fish with ON transection (ONT) were monitored by MEMRI up to 6 months postlesion (mpl).

Results:

Signal intensity profiles of the Mn2+‐enhanced ON were consistent with ON regeneration in the ONC+PNG and ONC+LI rat and mice groups, respectively, compared with the nonregenerating ONC groups. Furthermore, signal intensity profiles of the Mn2+‐enhanced ON obtained between 1 mpl and 6 mpl in the fish and frog groups, respectively, were consistent with spontaneous, complete ON regeneration.

Conclusion:

Taken together, these results demonstrate that MEMRI is a viable method for serial, in vivo monitoring of normal, induced, and spontaneously regenerating optic nerve axons in different species. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Three‐dimensional flow‐independent balanced steady‐state free precession vessel wall MRI of the popliteal artery: Preliminary experience and comparison with flow‐dependent black‐blood techniques
Authors: Kawaji Keigo , Nguyen Thanh D. , Zou Zhitong , Reig Beatriu , Winchester Priscilla A. , Shih Andrew , Spincemaille Pascal , Prince Martin R. , Wang Yi
Published: July 2011

Purpose:

To examine the feasibility of flow‐independent T2‐prepared inversion recovery (T2IR) black‐blood (BB) magnetization preparation for three‐dimensional (3D) balanced steady‐state free precession (SSFP) vessel wall MRI of the popliteal artery, and to evaluate its performance relative to flow‐dependent double inversion recovery (DIR), spatial presaturation (SPSAT), and motion‐sensitizing magnetization preparation (MSPREP) BB techniques in healthy volunteers.

Materials and Methods:

Eleven subjects underwent 3D MRI at 1.5 Tesla with four techniques performed in a randomized order. Wall and lumen signal‐to‐noise ratio (SNR), wall‐to‐lumen contrast‐to‐noise ratio (CNR), vessel wall area, and lumen area were measured at proximal, middle, and distal locations of the imaged popliteal artery. Image quality scores based on wall visualization and degree of intraluminal artifacts were also obtained.

Results:

In the proximal region, DIR and SPSAT had higher wall SNR and wall‐to‐lumen CNR than both MSPREP and T2IR. In the middle and distal regions, DIR and SPSAT failed to provide effective blood suppression, whereas MSPREP and T2IR provided adequate black blood contrast with comparable wall‐to‐lumen CNR and image quality.

Conclusion:

The feasibility of 3D SSFP imaging of the popliteal vessel wall using flow‐independent T2IR was demonstrated with effective blood suppression and good vessel wall visualization. Although DIR and SPSAT are effective for thin slab imaging, MSPREP and T2IR are better suited for 3D thick slab imaging. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Windowed stochastic proton decoupling for in vivo 13C magnetic resonance spectroscopy with reduced RF power deposition
Authors: Xiang Yun , Shen Jun
Published: July 2011

Purpose:

To propose a strategy for reducing radiofrequency (RF) power deposition by stochastic proton decoupling based on Rayleigh's theorem.

Materials and Methods:

Rayleigh's theorem was used to remove frequency components of stochastic decoupling over the 3.90–6.83 ppm range. [2‐13C] or [2,5‐13C2]glucose was infused intravenously to anesthetized rats. 13C labeling of brain metabolites was detected in the carboxylic/amide spectral region at 11.7 T using either the original stochastic decoupling method developed by Ernst or the proposed windowed stochastic decoupling method.

Results:

By restricting frequency components of stochastic decoupling to 1.91–3.90 ppm and 6.83–7.60 ppm spectral regions decoupling power deposition was reduced by ≈50%. The proposed windowed stochastic decoupling scheme is experimentally demonstrated for in vivo 13C MRS of rat brain at 11.7 T.

Conclusion:

The large reduction in decoupling power deposition makes it feasible to perform stochastic proton decoupling at very high magnetic fields for human brain 13C MRS studies. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Morphological and biochemical T2 evaluation of cartilage repair tissue based on a hybrid double echo at steady state (DESS‐T2d) approach
Authors: Welsch Goetz H. , Mamisch Tallal C. , Zak Lukas , Mauerer Andreas , Apprich Sebastian , Stelzeneder David , Marlovits Stefan , Trattnig Siegfried
Published: July 2011

Purpose:

To use a new approach which provides, based on the widely used three‐dimensional double‐echo steady‐state (DESS) sequence, in addition to the morphological information, the generation of biochemical T2 maps in one hybrid sequence.

Materials and Methods:

In 50 consecutive MRIs at 3.0 Tesla (T) after matrix‐associated autologous chondrocyte transplantation (MACT) of the knee, by the use this new DESS‐T2d approach, the morphological Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) score, as well as biochemical T2d values were assessed. Furthermore, these results were correlated to standard morphological sequences as well as to standard multi‐echo spin‐echo T2 mapping.

Results:

The MOCART score correlated (Pearson:0.945; P < 0.001) significantly as assessed with standard morphological sequences (68.8 ± 13.2) and the morphological images of the DESS T2d sequence (68.7 ± 12.6). T2 and T2d relaxation times (ms) were comparable in between the control cartilage (T2: 52.5 ± 11.4; T2d: 46.6 ± 10.3) and the repair tissue (T2: 54.4 ± 11.4; T2d: 47.5 ± 13.0) (T2: P = 0.157; T2d: P = 0.589). As expected, T2d values were lower than the standard‐T2 values, however, both functional relaxation times correlated significantly (Pearson:0.429; P < 0.001).

Conclusion:

The presented hybrid approach provides the possibility to combine morphological and biochemical MRI in one fast 3D sequence, and thus, may attract for the clinical use of biochemical MRI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
First order correction for T2*‐relaxation in determining contrast agent concentration from spoiled gradient echo pulse sequence signal intensity
Authors: De Naeyer Dieter , Debergh Isabelle , De Deene Yves , Ceelen Wim P. , Segers Patrick , Verdonck Pascal
Published: July 2011

Purpose:

To investigate the accuracy of a method neglecting T2*‐relaxation, for the conversion of spoiled gradient echo pulse sequence signal intensity to contrast agent (CA) concentration, in dynamic contrast enhanced MRI studies. In addition a new closed form conversion expression is proposed that accounts for a first order approximation of T2*‐relaxation.

Materials and Methods:

The accuracy of both conversion methods is compared theoretically by means of simulations for four pulse sequences from literature. Both methods are tested in vivo against the numerical conversion method for measuring the arterial input function in mice.

Results:

Simulations show that the T2*‐neglecting method underestimates typical tissue CA concentrations (0 mM to 2 mM) up to 6%, while the errors for arterial concentrations (0 mM to 10 mM) range up to 43%. The results from our first order method are numerically indistinguishable from the simulation input values in tumor tissue, while for arterial concentrations the error is reduced up to a factor 10. In vivo, peak Gd‐DOTA concentration is underestimated up to 14% with the T2*‐neglecting method and up to 0.9% with our first order method.

Conclusion:

Our conversion method reduces the underestimation of CA concentration severely in a broad physiological concentration range and is easy to perform in any clinical setting. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Compensation of RF field and receiver coil induced inhomogeneity effects in abdominal MR images by a priori knowledge on the human adipose tissue distribution
Authors: Würslin Christian , Springer Fabian , Yang Bin , Schick Fritz
Published: July 2011

Purpose:

To reliably compensate bias field effects in abdominal areas to accurately quantify visceral adipose tissue using standard T1‐weighted sequences on MR scanners with up to 3 Tesla (T) field strength.

Materials and Methods:

Compensation is achieved in two steps: The bias field is first estimated by picking and fitting sampling points from the subcutaneous adipose tissue, using active contours and a thin plate fitting spline. Then, additional sampling points from visceral adipose tissue compartments are detected by thresholding and the bias field estimation is refined. It was compared with an established method using a simulated abdominal image and real 3T data.

Results:

At low bias field amplitudes (40–50%), the simulation study showed a good reduction of the mean coefficients of variance (CV) for both approaches (>80%). At higher amplitudes, the CV reduction was significantly higher for our approach (83.6%), compared with LEMS (54.3%). In the real data study, our approach showed reliable reduction of the inhomogeneities, while the LEMS algorithm sometimes even amplified the inhomogeneities.

Conclusion:

The proposed method enables accurate and reliable segmentation of abdominal adipose tissue using simple thresholding techniques, even in severely corrupted images slices, obtained when using high field strengths and/or phased‐array coils. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Resolving arterial phase and temporal enhancement characteristics in DCE MRM at high spatial resolution with TWIST acquisition
Authors: Herrmann Karl‐Heinz , Baltzer Pascal A. , Dietzel Matthias , Krumbein Ines , Geppert Christian , Kaiser Werner A. , Reichenbach Jürgen R.
Published: July 2011

Purpose:

To investigate the potential of a view‐sharing 3D fast gradient‐echo sequence using pseudo random trajectories (TWIST) to achieve very short acquisition times with high in‐plane resolution and good volume coverage and its application to dynamic contrast‐enhanced (DCE) breast magnetic resonance imaging (MRI).

Materials and Methods:

Two versions of a 3D fast gradient echo TWIST sequence were implemented and applied to patients: First, an ultrafast TWIST acquisition (TA = 5.7 sec) in combination with a routine DCE MRM protocol to allow the extraction of arterial input functions and to resolve the first pass of the contrast agent. Second, a dynamic full coverage TWIST DCE acquisition (TA = 10.6 sec) in a repeat examination, replacing the routine DCE MRM sequence.

Results:

The ultrafast acquisition enabled extraction of arterial input functions and the monitoring of the contrast agent's first pass through vessels and lesions. The dynamic full coverage TWIST acquisition captured the initial dynamic slope of the signal time curve of lesions accurately, in contrast to the routine protocol.

Conclusion:

TWIST acquisitions proved very robust and offer high flexibility in protocol timing. The ultrafast protocol achieved 5.7 seconds time resolution with good image quality and can be combined with any established routine protocol. The full dynamics TWIST DCE protocol offers improved time resolution of the CE dynamic time‐course and closely matches the image quality of the routine protocol. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Chemical shift sodium imaging in a mouse model of thromboembolic stroke at 9.4 T
Authors: Heiler Patrick M. , Langhauser Friederike L. , Wetterling Friedrich , Ansar Saema , Grudzenski Saskia , Konstandin Simon , Fatar Marc , Meairs Stephen , Schad Lothar R.
Published: July 2011

Purpose:

To estimate changes in the 23Na density and in the 23Na relaxation time T2* in the anatomically small murine brain after stroke.

Materials and Methods:

Three‐dimensional acquisition weighted chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm3 was used for sodium imaging and relaxation parameter mapping. In vivo measurements of the mouse brain (n = 4) were performed 24 hours after stroke, induced by microinjection of purified murine thrombin into the right middle cerebral artery. The measurement time was 14 minutes in one mouse and 65 minutes in the other three. An exponential fit estimation of the free induction decay was calculated for each voxel enabling the reconstruction of locally resolved relaxation parameter maps.

Results:

The infarcted areas showed an increase in sodium density between 160% and 250%, while the T2* relaxation time increased by 5%–72% compared to unaffected contralateral brain tissue.

Conclusion:

23Na chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm3 enabled sodium imaging of the anatomical small mouse brain and the acquired data allowed calculating relaxation parameter maps and hence a more exact evaluation of sodium signal changes after stroke. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.
Investigation of the afterglow time regime in pulsed radiofrequency glow discharge time‐of‐flight mass spectrometry
Authors: González Gago C. , Bordel N. , Pereiro R. , Sanz‐Medel A.
Published: July 2011

The pulsed power operation mode of a radiofrequency (rf) glow discharge time‐of‐flight mass spectrometer was investigated, for several ions, in terms of intensity profiles along each pulse period. Particular attention was paid to the plateau and transient afterglow regions. An rf pulse period of 4 ms and a duty cycle of 50% was selected to evaluate the influence of discharge parameters in the afterglow delay and shape of Ar+, Ar2+ and several analytes (Br, Cl, Cu) contained in polymeric layers. Pulse shapes of Ar+ and Ar2+ ions vary with pressure and power. At low pressures the highest intensity is observed in the plateau while at higher pressures (>600 Pa) the afterpeak is the dominant region. Although the influence of the applied power is less noticeable, a widening of the afterglow time regime occurs for Ar+ when increasing the power. Maximum intensity of the argon signal is measured in the afterglow at 30 W, while the area of such afterpeak increases with power. The maximum intensity of Ar2+ is obtained at the highest power employed (60 W) and the ratio maximum intensity/afterglow area remains approximately constant with power. Analytes with ionization potentials below (Cu) or just above (Br) the argon metastable energy show maxima intensities after argon ions decay, indicating they could be ionized by collisions with metastable Ar atoms. Chlorine signals are observed in the afterglow despite their ionization potential is well above the energy of argon metastable levels. Moreover, they follow a similar pattern to that observed for Ar2+, indicating that charge‐transfer process with Ar2+ could play a significant role. Copyright © 2011 John Wiley & Sons, Ltd.
Proteomic characterisation of hydrothermal redox damage
Authors: Grosvenor Anita J , Morton James D , Dyer Jolon M
Published: July 2011

BACKGROUND: Peptide and protein damage contributes to the loss of quality and value in protein‐based food and textile products as well as to the degeneration of biological tissues such as hair and skin. The effects of elevated temperature on such substrates at the molecular level are, however, relatively unknown. This paper examines the response of peptides and proteins to hydrothermal damage using mass spectrometry and reports the location of molecular markers of hydrothermal damage within wool proteins.

RESULTS: The hydrothermal exposure of model peptides containing the oxidatively sensitive residues tryptophan and tyrosine revealed the formation of a number of products such as hydroxytryptophan and dihydrophenylalanine. A variety of degradation products were also observed in intermediate filament proteins, including products arising from deamidation and from oxidation of histidine, tyrosine and tryptophan residues.

CONCLUSION: The products observed to form during hydrothermal exposure indicated the involvement of reactive oxygen species. Molecular markers were identified within a proteinaceous system to allow the evaluation of damage type or severity. These findings have important implications for the thermal processing of foods and textiles. Copyright © 2011 Society of Chemical Industry
Potential and constraints in the development of animal industries in China
Authors: Liu Shimin , Cai Yunbo , Zhu Haiyan , Tan Zhiliang
Published: July 2011

Over the past three decades, the growth in terrestrial livestock and aquatic animal production in China has been much faster than the annual increase of 1.92% in total grain production. It was estimated that farming animals, including aquatic animals, would require a total of 860 million tons of feed in 2008, comprising almost equal portions of concentrates, pastures, and crop straw. Grain production amounted to 528 million tons in 2008, about half of which were available for use in animal feed after satisfying demand for human consumption. This situation will not change in the near future. Pastures from the natural grasslands supply about 290 million tons of dry matter, and are also unlikely to increase. In contrast, only one third of the 890 million tons of crop straw was used as animal feeds. We conclude that the availability of grain and pasture is the major constraint to further expansion of animal production, as well as crop straw which is not fully utilised. China needs to strategically structure the industries of its herbivores and the other domestic species, and to develop sustainable faming systems based on its available feed sources. Copyright © 2011 Society of Chemical Industry
Thin‐layer chromatographic plates with monolithic layer of silica: Production, physical–chemical characteristics, separation capabilities
Authors: Frolova Anastasiya M. , Konovalova Olga Y. , Loginova Lidia P. , Bulgakova Alena V. , Boichenko Alexander P.
Published: July 2011

The technique for production of thin‐layer chromatographic plates with fixed monolithic layer of sorbent was developed on the basis of investigation of factors affecting sorption capacity, sorption kinetics and mechanical stability of monoliths. The optimal reaction mixture for sol–gel synthesis of monoliths consisted of tetraethoxysilane, buffer solution with pH 7.4, N,N‐dimethylformamide, ethanol, polyethyleneglycol with molecular weight 1000 and cetylpyridinium chloride in molar ratio 1.0:4.6:1.4:7.6:0.26:8×10−3. On the basis of analysis of sorption kinetics of malachite green on the monoliths it was concluded that mechanism of sorption includes chemisorption. The optimized conditions for fixing the monolithic layer on the carrier and its drying allow obtaining undisturbed monolithic layer, which was used for test mixtures separation. The increase of monolithic layer thickness in comparison with ultrathin‐layer chromatographic plates allows detecting visually at reasonable concentrations and loaded sample volumes the spots of food and synthetic dyes.
Trends in intensive management of Alaska's grizzly bears, 1980–2010
Authors: Miller Sterling D. , Schoen John W. , Faro Jim , Klein David R.
Published: July 2011

Hunting regulations for grizzly bears (Ursus arctos) in much of Alaska since 1980 increasingly were designed to reduce bear abundance in the expectation such regulations would lead to increased harvests by hunters of moose (Alces alces) and caribou (Rangifer tarandus). Regulations were liberalized during 1980–2010 primarily in the area we termed the Liberal Grizzly Bear Hunting Area (hereafter Liberal Hunt Area) which encompassed 76.2% of Alaska. By 2010, these changes resulted in longer hunting seasons (100% of Liberal Hunt Area had seasons > 100 days, 99.7% > 200 days, and 67.8% > 300 days), more liberal bag limits (99.1% of the Liberal Hunt Area with a bag limit ≥ 1/yr and 10.1% with a bag limit ≥ 2/yr), and widespread waiver of resident tag fees (waived in 95.7% of the Liberal Hunt Area). During 1995–2010, there were 124 changes that made grizzly bear hunting regulations more liberal and two making them more conservative. The 4‐year mean for grizzly bear kills by hunters increased 213% between 1976–1980 (387 grizzly bears) and 2005–2008 (823 grizzly bears). Since 2000, long‐term research studies on grizzly populations in the Liberal Hunt Area have been terminated without replacement. Management of large predators by the State of Alaska is constrained by a 1994 state statute mandating “intensive management” in areas classified as important for human consumptive use of ungulates. Current grizzly bear management in the Liberal Hunt Area is inconsistent with the recommendations of the National Research Council's 1997 report on predator management in Alaska. Current attitudes, policies and absence of science‐based management of grizzly bears in Alaska are increasingly similar to those that resulted in the near extirpation of grizzly bears south of Canada in the 19th and 20th centuries. If current trends continue, they increase risks to portions of the largest and most intact population of grizzly bears in North America. © 2011 The Wildlife Society.
Cougar survival and source‐sink structure on Greater Yellowstone's Northern Range
Authors: Ruth Toni K. , Haroldson Mark A. , Murphy Kerry M. , Buotte Polly C. , Hornocker Maurice G. , Quigley Howard B.
Published: July 2011

We studied survival and causes of mortality of radiocollared cougars (Puma concolor) on the Greater Yellowstone Northern Range (GYNR) prior to (1987–1994) and after wolf (Canis lupus) reintroduction (1998–2005) and evaluated temporal, spatial, and environmental factors that explain variation in adult, subadult, and kitten survival. Using Program MARK and multimodel inference, we modeled cougar survival based on demographic status, season, and landscape attributes. Our best models for adult and independent subadults indicated that females survived better than males and survival increased with age until cougars reached older ages. Lower elevations and increasing density of roads, particularly in areas open to cougar hunting north of Yellowstone National Park (YNP), increased mortality risks for cougars on the GYNR. Indices of ungulate biomass, cougar and wolf population size, winter severity, rainfall, and individual characteristics such as the presence of dependent young, age class, and use of Park or Wilderness were not important predictors of survival. Kitten survival increased with age, was lower during winter, increased with increasing minimum estimates of elk calf biomass, and increased with increasing density of adult male cougars. Using our best model, we mapped adult cougar survival on the GYNR landscape. Results of receiver operating characteristic (ROC) analysis indicated a good model fit for both female (area under the curve [AUC] = 0.81, 95%CI = 0.70–0.92, n = 35 locations) and male cougars (AUC = 0.84, 95%CI = 0.74–0.94, n = 49 locations) relative to hunter harvest locations in our study area. Using minimum estimates of survival necessary to sustain the study population, we developed a source‐sink surface and we identify several measures that resource management agencies can take to enhance cougar population management based on a source‐sink strategy. © 2011 The Wildlife Society.
High‐precision mass spectrometric analysis using stable isotopes in studies of children
Authors: Schierbeek Henk , van den Akker Chris H.P. , Fay Laurent B. , van Goudoever Johannes B.
Published: July 2011

The use of stable isotopes combined with mass spectrometry (MS) provides insight into metabolic processes within the body. Herein, an overview on the relevance of stable isotope methodology in pediatric research is presented. Applications for the use of stable isotopes with MS cover carbohydrate, fat, and amino acid metabolism as well as body composition, energy expenditure, and the synthesis of specific peptides and proteins, such as glutathione and albumin. The main focus of these studies is on the interactions between nutrients and the endogenous metabolism within the body and how these factors affect the health of a growing infant. Considering that the early imprinting of metabolic processes hugely impacts metabolism (and thus functional outcome) later in life, research in this area is important and is advancing rapidly. The major fluxes on a metabolic level are the synthesis and breakdown rates. They can be quantified using kinetic tracer analysis and mathematical modeling. Organic MS and isotope ratio mass spectrometry (IRMS) are the two most mature techniques for the isotopic analysis of compounds. Introduction of the samples is usually done by coupling gas chromatography (GC) to either IRMS or MS because it is the most robust technique for specific isotopic analysis of volatile compounds. In addition, liquid chromatography (LC) is now being used more often as a tool for sample introduction of both volatile and non‐volatile compounds into IRMS or MS for 13C isotopic analyses at natural abundances and for 13C‐labeled enriched compounds. The availability of samples is often limited in pediatric patients. Therefore, sample size restriction is important when developing new methods. Also, the availability of stable isotope‐labeled substrates is necessary for measurements of the kinetics and concentrations in metabolic studies, which can be a limiting factor. During the last decade, the availability of these substrates has increased. Furthermore, improvements in the accuracy, precision, and sensitivity of existing techniques (such as GC/IRMS) and the development of new techniques (such as LC/IRMS) have opened up new avenues for tackling these limitations. © 2011 Wiley Periodicals, Inc. Mass Spec Rev 31:312–330, 2012
Crack patterns in clayey soils: Experiments and modeling
Authors: Trabelsi H. , Jamei M. , Zenzri H. , Olivella S.
Published: July 2011

The paper presents an experimental and numerical study to investigate the behavior of desiccated clayey soils. The performed tests permit to evaluate the crack pattern as well as the tensile strength as a function of suction. A new model that relates the porosity evolution to the suction and to the tensile strength was developed and implemented in the finite element program CODE_BRIGHT. The proposed model captured the initiation and propagation of cracks in a thin layer of desiccated clay and predicted crack patterns in terms of the Minkowski densities (i.e. average crack length and crack intensity factor). The effect of the heterogeneity of the tested specimens, modeled by random clusters, was also quantified. Copyright © 2011 John Wiley & Sons, Ltd.
Effects of epilepsy and selected antiepileptic drugs on risk of myocardial infarction, stroke, and death in patients with or without previous stroke: a nationwide cohort study
Authors: Olesen Jonas Bjerring , Abildstrøm Steen Zabell , Erdal Jesper , Gislason Gunnar H. , Weeke Peter , Andersson Charlotte , Torp‐Pedersen Christian , Hansen Peter Riis
Published: July 2011

Purpose

Patients with epilepsy have increased morbidity and mortality. We evaluated the risk of myocardial infarction (MI), stroke, and death associated with epilepsy and examined if this risk was modified by treatment with antiepileptic drugs (AEDs).

Methods

A cohort consisting of the Danish population was followed from January 1997 to December 2006. The risk of MI, stroke, cardiovascular death, and all‐cause death associated with epilepsy was estimated by multivariable Cox proportional hazard models stratified for occurrence of previous stroke. AED use was determined at baseline, and risks associated with exposure to individual AEDs were examined in patients with epilepsy.

Results

In patients without previous stroke, AED‐treated epilepsy was associated with an increased risk of MI (hazard ratio [HR], 1.09; 95%CI, 1.00–1.19), stroke (HR, 2.22; 95%CI, 2.09–2.36), cardiovascular death (HR, 1.64; 95%CI, 1.57–1.72), and all‐cause death (HR, 1.92; 95%CI, 1.86–1.97). Compared with carbamazepine monotherapy, valproate was associated with a decreased risk of MI (HR, 0.72; 95%CI, 0.59–0.87) and stroke (HR, 0.86; 95%CI, 0.76–0.96), oxcarbazepine and phenobarbital with increased risk of cardiovascular death (HR, 1.10; 95%CI, 1.02–1.19 and HR, 1.08; 95%CI, 1.00–1.17, respectively) and all‐cause death (HR, 1.11; 95%CI, 1.05–1.18 and HR, 1.18; 95%CI, 1.12–1.25, respectively), and oxcarbazepine with increased risk of stroke (HR, 1.21; 95%CI, 1.10–1.34), in patients with epilepsy.

Conclusions

Patients with epilepsy exhibit increased risk of MI, stroke, cardiovascular death, and all‐cause death. Compared with carbamazepine monotherapy, valproate may decrease, and oxcarbazepine and phenobarbital may increase, the risk of adverse cardiovascular events in these patients. Copyright © 2011 John Wiley & Sons, Ltd.
Reactivity of carbene•phosphine dimers: proton affinity revisited
Authors: Liu Min , Chen Mu , Zhang Sisi , Yang Ill , Buckley Brian , Lee Jeehiun K.
Published: July 2011

The gas phase reactivity of N‐heterocyclic carbenes versus tricyclohexylphosphine (PCy3) is examined computationally and experimentally. New measurements indicate that dimethylimidazol‐ and 1‐ethyl‐3‐methylimidazol‐2‐ylidene are more basic than PCy3, in contrast to previous measurements made by us and by others. Proton‐bound dimers of the carbenes and PCy3 are also found to exhibit interesting reactivity involving phosphine alkylation, cyclohexene elimination, and/or ethylene elimination. This novel reactivity is further probed and discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Generation and reactivities of triplet diphenylcarbenes protected by bulky groups as para substituents
Authors: Hirai Katsuyuki , Hatanaka Keiji , Yamaguchi Tsuyoshi , Miyajima Akiko , Kitagawa Toshikazu , Tomioka Hideo
Published: July 2011

Bis(2,6‐dimethylphenyl)diazomethane (1b‐N2) having 10‐(4‐tert‐butyl‐2,6‐dimethylphenyl)‐2,7‐di(phenylethynyl)‐9‐anthrylethynyl groups at the 4,4′‐positions was synthesized. Triplet diphenylcarbene 31b was generated by photolysis of the precursor and was characterized by electron spin resonance and UV–Vis spectroscopies at low temperature, and laser flash photolysis techniques at room temperature. Irradiation of 1b‐N2 in a 2‐methyltetrahydrofuran matrix at 77 K gave electron spin resonance signals ascribable to triplet carbene 31b. UV–Vis spectra of 31b were obtained by irradiating 1b‐N2 under identical conditions. The laser flash photolysis of 1b‐N2 in a degassed benzene solution gave transient absorption bands ascribable to 31b, which decayed in a first‐order fashion with a rate constant of 0.46 s–1. The carbene was shown to be less reactive than the triplet bis(2,6‐dimethylphenyl)carbene (31a) having 9‐anthrylethynyl groups at the 4,4′‐positions, which decayed in a second‐order fashion with a rate constant (2 k/εl) of 0.69 s–1. Triplet carbene 31b was trapped by oxygen to generate ketone oxide 1b‐O with a rate constant of 1.9 × 107 M–1 s–1 and also by 1,4‐cyclohexadiene with a rate constant of 1.2 M–1 s–1. Similar studies with diphenyldiazomethanes (1c‐N2 and 1 d‐N2) having bulky substituents, 10‐(4‐tert‐butyl‐2,6‐dimethylphenyl)‐2,7‐bis[3,5‐di(phenylethynyl)phenylethynyl]‐9‐anthrylethynyl and 10‐(4‐tert‐butyl‐2,6‐dimethylphenyl)‐2,7‐bis(9‐triptycylethynyl)‐9‐anthrylethynyl groups at the 4,4′‐positions respectively indicated that the corresponding triplet carbenes 31c and 31 d were more persistent than 31b. Steady‐state irradiation of 1a‐N2, 1c‐N2, and 1 d‐N2 in degassed benzene afforded tetraarylethenes 2a, 2c, and 2d in 83, 50, and 51% yield, respectively. Copyright © 2011 John Wiley & Sons, Ltd.
Regioselective grignard metathesis reaction of 2,5‐dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and kumada coupling polymerization
Authors: Takagi Koji , Joo Hyunho , Yamashita Yusuke , Kawagita Eiki , Torii Chikako
Published: July 2011

2,5‐Dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene (DBPyTh) was synthesized by the Suzuki coupling reaction between two aromatic compounds followed by the bromination. The Grignard metathesis reaction of DBPyTh with isopropylmagnesium chloride proceeded in 85% conversion and the regioselective halogen–metal exchange at the 2‐position was confirmed. Namely, 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and 2‐bromo‐5‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene were generated in 90:10 molar ratio. Subsequently, the Kumada coupling polymerization was carried out using 1,3‐bis(diphenylphosphinopropane)nickel(II) dichloride to obtain poly(3‐(6′‐hexylpyridine‐2′‐yl)thiophene) (PolyPyTh). The polymer molecular weight could be roughly controlled by the catalyst concentration and the molecular weight distribution ranged from 1.25 to 1.80. The gas chromatograph analysis indicated that 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene was preferentially polymerized in 90% conversion and the percentage of the head‐to‐tail content (regioregularity) was calculated to be 96%. The matrix‐assisted laser desorption/ionization time‐of‐fright mass spectrum indicated that both polymer chain ends were substituted with the hydrogen atom. The absorption maxima of polymer in CHCl3 and thin film were observed at 447 and 457 nm, respectively, which were blue‐shifted compared with poly(3‐(4′‐octylphenyl)thiophene). From the CV measurement of the polymer thin film, highest occupied molecular orbital (HOMO) (−5.31 eV) and lowest unoccupied molecular orbital (LUMO) (−3.76 eV) energy levels were calculated from the oxidation and reduction onset potentials, respectively, and the electrochemical band gap energy was determined to be 1.62 eV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis and characterization of amphiphilic heterograft copolymers with PAA and PS side chains via “Grafting from” approach
Authors: Fan Xiaoshan , Wang Guowei , Zhang Zhen , Huang Junlian
Published: July 2011

The amphiphilic heterograft copolymers poly(methyl methacrylate‐co‐2‐(2‐bromoisobutyryloxy)ethyl methacrylate)‐graft‐(poly(acrylic acid)/polystyrene) (P(MMA‐co‐BIEM)‐g‐(PAA/PS)) were synthesized successfully by the combination of single electron transfer‐living radical polymerization (SET‐LRP), single electron transfer‐nitroxide radical coupling (SET‐NRC), atom transfer radical polymerization (ATRP), and nitroxide‐mediated polymerization (NMP) via the “grafting from” approach. First, the linear polymer backbones poly(methyl methacrylate‐co‐2‐(2‐bromoisobutyryloxy)ethyl methacrylate) (P(MMA‐co‐BIEM)) were prepared by ATRP of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) and subsequent esterification of the hydroxyl groups of the HEMA units with 2‐bromoisobutyryl bromide. Then the graft copolymers poly(methyl methacrylate‐co‐2‐(2‐bromoisobutyryloxy)ethyl methacrylate)‐graft‐poly(t‐butyl acrylate) (P(MMA‐co‐BIEM)‐g‐PtBA) were prepared by SET‐LRP of t‐butyl acrylate (tBA) at room temperature in the presence of 2,2,6,6‐tetramethylpiperidin‐1‐yloxyl (TEMPO), where the capping efficiency of TEMPO was so high that nearly every TEMPO trapped one polymer radicals formed by SET. Finally, the formed alkoxyamines via SET‐NRC in the main chain were used to initiate NMP of styrene and following selectively cleavage of t‐butyl esters of the PtBA side chains afforded the amphiphilic heterograft copolymers poly(methyl methacrylate‐co‐2‐(2‐bromoisobutyryloxy)ethyl methacrylate)‐graft‐(poly(t‐butyl acrylate)/polystyrene) (P(MMA‐co–BIEM)‐g‐(PtBA/PS)). The self‐assembly behaviors of the amphiphilic heterograft copolymers P(MMA‐co–BIEM)‐g‐(PAA/PS) in aqueous solution were investigated by AFM and DLS, and the results demonstrated that the morphologies of the formed micelles were dependent on the grafting density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Annealing of melt‐crystallized polyethylene and its influence on microstructure and mechanical properties: A comparative study on branched and linear polyethylenes
Authors: Song Shijie , Feng Jiachun , Wu Peiyi
Published: July 2011

Annealing treatments have been performed on two melt‐crystallized polyethylenes (PE) with different topologies, namely highly branched and linear PE, to comparatively investigate the microstructural evolution and corresponding changes of mechanical property. It shows that annealing induced different degrees of variation in the lamellar rearrangement of the two PEs. Branched PE, which incorporates comonomers on the backbones, shows a more versatile annealing effect when compared with the linear counterpart. With respect to PEs, it is for the first time a connection was made between the annealing‐induced microstructural changes and an important but less understood property known as heat distortion temperature (HDT). It shows that at lower annealing temperatures, the improvement of HDT can be well correlated to the increased crystallinity induced by lamellar rearrangement for both PEs. However, for branched PE, the contribution of crystallinity is weakened at higher annealing temperatures and the dominant factor on HDT was replaced by the relaxation of lamellar structure. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1347–1359, 2011
In situ synthesis of ZnO nanocrystal/PET hybrid nanofibers via electrospinning
Authors: Zhang Junhua , Wen Bin , Wang Feng , Ding Yanfen , Zhang Shimin , Yang Mingshu
Published: July 2011

Hybrid nanofibers of ZnO precursors/PET were fabricated by electrospinning a nonaqueous poly(ethylene terephthalate) (PET) solution containing zinc acetate dihydrate. Scanning electron microscopy images showed that the as prepared nanofibers had smooth and uniform surfaces, and the diameter was decreased with increasing zinc acetate dihydrate content and reducing PET concentration. After the treatment by a mild process of immersing the fibers in ammonia‐ethanol mixtures (pH ≈ 9–11), the surface of the nanofibers became rough during the formation of ZnO nanocrystals in the fibers. High resolution transmission electron microscopy images showed that the mean particle size became smaller with increasing diameter of the polymer fibers and decreasing content of ZnO. Fourier transform infrared spectra confirmed the ZnO formation in the hybrid nanofibers. X‐ray diffractometry patterns indicated that ZnO had the Wurtzite structure. The formation and growth of ZnO nanocrystals in the nanofiber matrices was also influenced by the various other parameters, that is, the pH value of the reaction solution, the content of zinc acetate dihydrate within the fibers, the reaction time and temperature. Photoluminescence spectra under excitation at 300 nm revealed a broad and intense ultraviolet emission. The UV‐visible diffuse reflectance spectra demonstrated the blue shift in the absorbance curve, which was ascribed to the quantum confinement effects of ZnO nanoparticles in the hybrid materials. These hybrid nanofibers can potentially be used in light emitters, chemical sensors, photo‐catalysts and solar cells. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1360–1368, 2011
Duality in strongly interacting systems: 𝒩 = 2 SUSY Yang‐Mills and the quantum Hall effect
Authors: Dolan B.P.
Published: July 2011

Classical solutions of the vacuum Maxwell's equations exhibit a SO(2) duality symmetry, which is enhanced to Sl(2,R) when dilaton and axion fields are included. Quantum effects break this symmetry but semi‐classically Sl(2,Z) symmetry, or a sub‐group thereof, survives in Dirac‐Schwinger‐Zwanziger quantisation. Even this symmetry is expected to be broken in the full theory of quantum electrodynamics, but a modular sub‐group survives as an infinite discrete symmetry of the vacua of 𝒩 = 2 supersymmetric Yang‐Mills theory. An analogous situation occurs in the quantum Hall effect, where different quantum Hall states are related by a modular symmetry which is a sub‐group of Sl(2,Z). The similarities between the quantum Hall effect and supersymmetric Yang‐Mills are reviewed and a possible link via the gauge/gravity correspondence is described. Scaling exponents in the quantum Hall effect are derived using the gauge‐gravity correspondence.
Non‐singular superstring cosmology in two dimensions
Authors: Partouche H.
Published: July 2011

We review a recently proposed approach to construct superstring cosmological evolutions, which are free of Hagedorn instabilities and initial singularities. We illustrate these ideas in hybrid models in two dimensions.
Bifenthrin longevity at the termiticidal application rate
Authors: Peterson Chris J
Published: July 2011

BACKGROUND: The longevity, mobility and insecticidal activity of bifenthrin at the termiticidal application rate for perimeter treatment were investigated in packed‐soil columns in the laboratory and greenhouse.

RESULTS: Bifenthrin was not detected in the eluates of packed‐soil cones over a period of 6 months. In larger pipe plots incorporating bifenthrin into the top 15 cm of the soil, the compound degraded in a biphasic fashion. Within the treated soil, the effect of vegetation on the amount of bifenthrin remaining in the soil depended on soil depth and time, and soil half‐lives were longer in non‐vegetated soil. Bifenthrin residues were higher in the top 7.5 cm of soil and declined over time. Movement of bifenthrin into the top untreated soil depth was observed, but much less was observed in lower depths. The soil remained toxic to termites in 3 day and 7 day forced exposure bioassays for the 30 month duration of the study.

CONCLUSIONS: Concentrations of bifenthrin will remain in the soil at levels sufficient to kill termites for more than 30 months. Published 2011 by John Wiley & Sons, Ltd.
Integrated management of Thrips tabaci (Thysanoptera: Thripidae) on onion in north‐western Italy: basic approaches for supervised control
Authors: Mautino Giulia C , Bosco Lara , Tavella Luciana
Published: July 2011

BACKGROUND: Thrips tabaci Lindeman (Thysanoptera: Thripidae) is a major pest on onion, Allium cepa L., worldwide. In 2010, research was conducted in a commercial onion field in north‐western Italy in order (i) to evaluate the efficacy of different insecticides and of the SAR activator acibenzolar‐S‐methyl, (ii) to correlate thrips infestation levels with bulb size and weight at harvest and (iii) to implement a reliable thrips sampling method. Efficacy of the three active ingredients spinosad, lambda‐cyhalothrin and acibenzolar‐S‐methyl on local thrips populations were also evaluated in laboratory bioassays.

RESULTS: During field surveys, the highest and the lowest thrips infestations were observed in plots treated with lambda‐cyhalothrin and with spinosad and acibenzolar‐S‐methyl respectively. The effectiveness of spinosad was also confirmed in laboratory bioassays. At harvest, bulb size and weight did not significantly differ between treatments. A high correlation with visual inspection made plant beating a suitable sampling method for routine practice, enabling a good estimate of thrips infestation.

CONCLUSION: Damage caused by thrips is often not severe enough to warrant the frequent pesticide applications the crops receive in north‐western Italy. The use of spinosad and acibenzolar‐S‐methyl is suggested as an alternative to conventional insecticides for the preservation of natural enemies. Copyright © 2011 Society of Chemical Industry
Susceptibility of Aphelinus certus to foliar‐applied insecticides currently or potentially registered for soybean aphid control
Authors: Frewin Andrew J , Schaafsma Arthur W , Hallett Rebecca H
Published: July 2011

BACKGROUND: Soybean aphid, a serious economic pest of soybean in North America, is currently managed by applying non‐selective foliar insecticides during outbreaks according to decision thresholds and crop maturity. Natural enemies, such as the parasitoid Aphelinus certus Yasnosh, potentially play an important role in suppressing soybean aphid. Using selective insecticides that preserve A. certus may enhance the biological control service they provide and thus prevent or reduce the severity of soybean aphid outbreaks. The toxicity of five insecticides (λ‐cyhalothrin, dimethoate, flonicamid, mineral oil, spirotetramat) and the biopesticide Beauveria bassiana to A. certus was assessed.

RESULTS: The LD50 values of λ‐cyhalothrin and dimethoate were similar; however, the hazard quotient of dimethoate was greater than that of λ‐cyhalothrin. In a screening bioassay, the descending order of toxicity for the recommended rates 48 h after application was dimethoate > λ‐cyhalothrin > flonicamid > mineral oil > Beauveria bassiana > spirotetramat.

CONCLUSIONS: Overall, λ‐cyhalothrin and dimethoate were both harmful to A. certus. The other insecticides tested were harmless to A. certus and are potential candidates for inclusion in soybean aphid management programs. Copyright © 2011 Society of Chemical Industry
Ultrafast magnetization dynamics of Gd(0001): Bulk versus surface
Authors: Sultan Muhammad , Melnikov Alexey , Bovensiepen Uwe
Published: July 2011

Ultrafast laser‐induced demagnetization of Gd(0001) has been investigated by magneto‐induced optical second harmonic generation and the magneto‐optical Kerr effect which facilitate a comparison of surface and bulk dynamics. We observe pronounced differences in the transient changes of the surface and bulk sensitive magneto‐optical signals which we attribute to transfer of optically excited, spin‐polarized carriers between surface and bulk states of the Gd(0001) film. A fluence dependent analysis of the bulk magnetization dynamics results in a weak variation of the demagnetization time constant, which starts at about 0.7 ps and increases by 10% within a fluence variation up to 1 mJ/cm2. We compare these results with fluence dependent changes in the transient energy density calculated by the two temperature model. The determined characteristic times of excess energy transfer from the electron system to the lattice, which is mediated by e–ph scattering, range from 0.2 to 0.6 ps. Such a more pronounced fluence dependent change in the characteristic time compared to the observed rather weakly varying demagnetization times suggests a more advanced description of the optically excited state than by the two‐temperature model.
Magnetic properties and superconductivity of nano‐width crystallite interfaces of bicrystals and tricrystals of Bi1−x–Sbx (x ≤ 0.2) alloys
Authors: Muntyanu F. M. , Gilewski A. , Nenkov K. , Zaleski A. J. , Chistol V.
Published: July 2011

The magnetic properties of bicrystals and tricrystals of Bi1−x–Sbx (x ≤ 0.2) alloys were studied in a temperature range of 1.8–100 K. The ferromagnetic‐like hysteresis loops are found in tricrystals and some bicrystals. We revealed that nano‐width crystallite interfaces (∼100 nm) exhibit superconducting behavior, whereas the single crystalline samples are not superconducting. The onset of superconducting transition (∼36 K) in some of these interfaces considerably exceeds the values of other semimetal nanoobjects.
Structure and reactivity of baicalein radical cation
Authors: Marković Zoran S. , Marković Svetlana , Dimitrić Marković Jasmina M. , Milenković Dejan
Published: July 2011

Neutral baicalein, corresponding radical cation, and three possible radicals obtained by proton removal from the radical cation were investigated using density functional theory. The structure and UV spectrum of baicalein were very well reproduced by the B3LYP/6‐311+G(2df,p) level of theory. The results showed that the loss of an electron from baicalein molecule induced the transfer of H4 to O5. The reasons for this rearrangement were pointed out. It was found that delocalization of spin density is most pronounced in the thermodynamically most stable C6OH radical. It was supposed that this radical plays a significant role in the antioxidant activity of baicalein within the single‐electron transfer‐proton transfer mechanism. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011