bluuebunny/crossref_metadata_2025 huggingface dataset:
Isotope effects in N2O photolysis from first principles
Authors: Schmidt J. A. , Johnson M. S. , Schinke R.
Published: September 2011

Abstract. For the first time, accurate first principles potential energy surfaces allow N2O cross sections and isotopic fractionation spectra to be derived that are in agreement with all available experimental data, extending our knowledge to a much broader range of conditions. Absorption spectra of rare N- and O-isotopologues (15N14N16O, 14N15N16O, 15N216O, 14N217O and 14N218O) calculated using wavepacket propagation are compared to the most abundant isotopologue (14N216O). The fractionation constants as a function of wavelength and temperature are in excellent agreement with experimental data. The study shows that excitations from the 3rd excited bending state, (0,3,0), and the first combination state, (1,1,0), are important for explaining the isotope effect at wavelengths longer than 210 nm. Only a small amount of the mass independent oxygen isotope anomaly observed in atmospheric N2O samples can be explained as arising from photolysis.
Technical Note: In-situ derivatization thermal desorption GC-TOFMS for direct analysis of particle-bound non-polar and polar organic species
Authors: Orasche J. , Schnelle-Kreis J. , Abbaszade G. , Zimmermann R.
Published: September 2011

Abstract. An in-situ derivatization thermal desorption method followed by gas chromatography and time-of-flight mass spectrometry (IDTD-GC-TOFMS) was developed for determination of polar organic compounds together with non-polar compounds in one measurement. Hydroxyl and carboxyl groups of compounds such as anhydrous sugars, alcohols and phenols, fatty acids and resin acids are targets of the derivatization procedure. Derivatization is based on silylation with N-Methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) during the step of thermal desorption. The high temperature of 300 °C during desorption is utilized for the in-situ derivatization on the collection substrate (quartz fibre filters) accelerating the reaction rate. Thereby, the analysis time is as short as without derivatization. At first the filter surface is dampened with derivatization reagent before insertion of the sample into the thermal desorption unit. To ensure ongoing derivatization during thermal desorption the carrier gas is enriched with MSTFA until the desorption procedure is finished. The precisions of all studied analytes were below 17 % within a calibration range from 22 pg (abietic acid) up to 342 ng (levoglucosan). Limits of quantification (LOQ) for polycyclic aromatic hydrocarbons (PAH) were between 1 pg (fluoranthene) and 8 pg (indeno[1,2,3-cd]pyrene), for resin acids 37–102 pg and for studied phenols 4–144 pg. LOQ for levoglucosan was 17 pg.
Direct ecosystem fluxes of volatile organic compounds from oil palms in South-East Asia
Authors: Misztal P. K. , Nemitz E. , Langford B. , Di Marco C. F. , Phillips G. J. , Hewitt C. N. , MacKenzie A. R. , Owen S. M. , Fowler D. , Heal M. R. , Cape J. N.
Published: September 2011

Abstract. This paper reports the first direct eddy covariance fluxes of reactive biogenic volatile organic compounds (BVOCs) from oil palms to the atmosphere using proton-transfer-reaction mass spectrometry (PTR-MS), measured at a plantation in Malaysian Borneo. At midday, net isoprene flux constituted the largest fraction (84 %) of all emitted BVOCs measured, at up to 30 mg m−2 h−1 over 12 days. By contrast, the sum of its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) exhibited clear deposition of 1 mg m−2 h−1, with a small average canopy resistance of 230 s m−1. Approximately 15 % of the resolved BVOC flux from oil palm trees could be attributed to floral emissions, which are thought to be the largest reported biogenic source of estragole and possibly also toluene. Although on average the midday volume mixing ratio of estragole exceeded that of toluene by almost a factor of two, the corresponding fluxes of these two compounds were nearly the same, amounting to 0.81 and 0.76 mg m−2 h−1, respectively. By fitting the canopy temperature and PAR response of the MEGAN emissions algorithm for isoprene and other emitted BVOCs a basal emission rate of isoprene of 7.8 mg m−2 h−1 was derived. We parameterise fluxes of depositing compounds using a resistance approach using direct canopy measurements of deposition. Consistent with Karl et al. (2010), we also propose that it is important to include deposition in flux models, especially for secondary oxidation products, in order to improve flux predictions.
Carbon transport by the Lena River from its headwaters to the Arctic Ocean, with emphasis on fluvial input of terrestrial particulate organic carbon vs. carbon transport by coastal erosion
Authors: Semiletov I. P. , Pipko I. I. , Shakhova N. E. , Dudarev O. V. , Pugach S. P. , Charkin A. N. , McRoy C. P. , Kosmach D. , Gustafsson Ö.
Published: September 2011

Abstract. The Lena River integrates biogeochemical signals from its vast drainage basin, and the integrated signal reaches far out over the Arctic Ocean. Transformation of riverine organic carbon (OC) into mineral carbon, and mineral carbon into the organic form in the Lena River watershed, can be considered to be quasi-steady-state processes. An increase in Lena discharge exerts opposite effects on total organic (TOC) and total inorganic (TCO2) carbon: TOC concentration increases, while TCO2 concentration decreases. Significant inter-annual variability in mean values of TCO2, TOC, and their sum (total carbon, TC) has been found. This variability is determined by changes in land hydrology which cause differences in the Lena River discharge. There is a negative correlation in the Lena River between TC in September and its mean discharge in August; a time shift of about one month is required for water to travel from Yakutsk to the Laptev Sea. Total carbon entering the sea with the Lena discharge is estimated to be almost 10 Tg C yr−1. The annual Lena River discharge of particulate organic carbon (POC) can be as high as 0.38 Tg (moderate to high estimate). If we instead accept Lisytsin's (1994) statement that 85–95 % of total particulate matter (PM) (and POC) precipitates on the marginal "filter", then only about 0.03–0.04 Tg of Lena River POC reaches the Laptev Sea. The Lena's POC export would then be two orders of magnitude less than the annual input of eroded terrestrial carbon onto the shelf of the Laptev and East Siberian seas, which is estimated to be about 4 Tg. Observations support the hypothesis of a dominant role for coastal erosion (Semiletov, 1999a, b) in East Siberian Arctic Shelf (ESAS) sedimentation and the dynamics of the carbon/carbonate system. The Lena River is characterized by relatively high concentrations of the primary greenhouse gases, dissolved carbon dioxide (CO2) and methane (CH4). During all seasons the river is supersaturated in CO2 compared to the atmosphere, by up to 1.5–2 fold in summer, and 4–5 fold in winter. This results in a significant CO2 supersaturation in the adjacent coastal sea. Localized areas of dissolved CH4 along the Lena River and in the Lena delta channels may reach 100 nM, but the CH4 concentration decreases to 5–20 nM towards the sea, which suggests that riverborne export of CH4 plays but a minor role in determining the ESAS CH4 budget in coastal waters. Instead, the seabed appears to be the source that provides most of the CH4 to the Arctic Ocean.
Biogeochemical factors affecting mercury methylation rate in two contaminated floodplain soils
Authors: Frohne T. , Rinklebe J. , Langer U. , Du Laing G. , Mothes S. , Wennrich R.
Published: September 2011

Abstract. An automated biogeochemical microcosm system allowing controlled variation of redox potential (EH) in soil suspensions was used to assess the effect of various factors on the mobility of mercury (Hg) as well as on the methylation of Hg in two contaminated floodplain soils with different Hg concentrations (approximately 5 mg kg−1 Hg and >30 mg kg−1 Hg). The experiment was conducted under stepwise variation from reducing (approximately −350 mV at pH 5) to oxidizing conditions (approximately 600 mV at pH 5). Results of phospholipid fatty acids (PLFA) analysis indicate the occurrence of sulfate reducing bacteria (SRB) such as Desulfobacter species (10me16:0, cy17:0, 10me18:0, cy19:0) or Desulfovibrio species (18:2ω6,9), which are considered to promote Hg methylation. The products of the methylation process are lipophilic, highly toxic methyl mercury species such as the monomethyl mercury ion [MeHg+], which is named as MeHg here. The ln(MeHg/Hgt) ratio is assumed to reflect the net production of monomethyl mercury normalized to total dissolved Hg (Hgt) concentration. This ratio increases with rising dissolved organic carbon (DOC) to Hgt ratio (lnDOC/lnHgt ratio) (R2 = 0.39, p < 0.0001, n = 63) whereas the relation between ln(MeHg/Hgt) ratio and lnDOC is weaker (R2 = 0.09; p < 0.05; n = 63). In conclusion, the DOC/Hgt ratio might be a more important factor for the Hg net methylation than DOC alone in the current study. Redox variations seem to affect the biogeochemical behavior of dissolved inorganic Hg species and MeHg indirectly through related changes in DOC, sulfur cycle, and microbial community structure whereas E,H and pH values, as well as concentration of dissolved Fe,3+/Fe2+ and Cl− seem to play subordinate roles in Hg mobilization and methylation under our experimental conditions.
Entropy production of soil hydrological processes and its maximisation
Authors: Porada P. , Kleidon A. , Schymanski S. J.
Published: September 2011

Abstract. Hydrological processes are irreversible and produce entropy. Hence, the framework of non-equilibrium thermodynamics is used here to describe them mathematically. This means flows of water are written as functions of gradients in the gravitational and chemical potential of water between two parts of the hydrological system. Such a framework facilitates a consistent thermodynamic representation of the hydrological processes in the model. Furthermore, it allows for the calculation of the entropy production associated with a flow of water, which is proportional to the product of gradient and flow. Thus, an entropy budget of the hydrological cycle at the land surface is quantified, illustrating the contribution of different processes to the overall entropy production. Moreover, the proposed Principle of Maximum Entropy Production (MEP) can be applied to the model. This means, unknown parameters can be determined by setting them to values which lead to a maximisation of the entropy production in the model. The model used in this study is parametrised according to MEP and evaluated by means of several observational datasets describing terrestrial fluxes of water and carbon. The model reproduces the data with good accuracy which is a promising result with regard to the application of MEP to hydrological processes at the land surface.
Association of Cogan-Reese Syndrome, Exfoliation Syndrome, and Secondary Open-Angle Glaucoma
Authors: Holló Gábor , Kóthy Péter , Konstas Anastasios G.P.
Published: September 2011

Purpose

To present a case with co-existence of Cogan-Reese syndrome and exfoliation syndrome.

Case report

A 72-year-old Caucasian woman presented for consultation due to uncontrolled intraocular pressure (IOP) of the right eye. Clinical examination revealed the presence of Cogan-Reese syndrome and exfoliation syndrome OD. This eye exhibited elevated IOP, open anterior chamber angle, advanced glaucomatous optic nerve head damage, and severe glaucomatous visual field loss. The left eye was completely normal without IOP elevation or visual field damage. To our knowledge this is the first case report demonstrating the coexistence of the Cogan-Reese syndrome, exfoliation syndrome, and secondary open-angle glaucoma. Since both syndromes frequently lead to secondary open-angle glaucoma, it is not feasible to determine with certainty which condition was the cause of secondary open-angle glaucoma in our case. It is conceivable that both conditions contributed to glaucoma development.

Conclusions

Cogan-Reese syndrome, exfoliation syndrome and secondary open-angle glaucoma may present on the same eye.
Trends in stroke hospitalizations and associated risk factors among children and young adults, 1995–2008
Authors: George Mary G. , Tong Xin , Kuklina Elena V. , Labarthe Darwin R.
Published: September 2011

Objective:

The aim of this study was to determine acute stroke hospitalization rates for children and young adults and the prevalence of stroke risk factors among children and young adults hospitalized for acute stroke.

Methods:

The study population consisted of 1995–2008 hospitalizations from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project. Subarachnoid hemorrhage, intracerebral hemorrhage, and ischemic stroke hospitalizations were identified by the primary International Classification of Diseases, 9th ed, Clinical Modification (ICD‐9‐CM) code. Seven consecutive 2‐year time intervals were selected. Three age groups were utilized: 5 to 14 years, 15 to 34 years, and 35 to 44 years. Stroke risk factors and comorbidities among those hospitalized with acute stroke were identified by secondary ICD‐9‐CM codes.

Results:

During the period of study, the prevalence of hospitalizations of acute ischemic stroke increased among all age and gender groups except females aged 5 to 14 years. Females aged 15 to 34 years and males and females aged 35 to 44 years showed a decrease in the prevalence of hospitalizations for subarachnoid hemorrhage, whereas females aged 5 to 14 years showed increases for subarachnoid hemorrhage. Hypertension, diabetes, obesity, lipid disorders, and tobacco use were among the most common coexisting conditions, and their prevalence increased from 1995 to 2008 among adolescents and young adults (aged 15–44 years) hospitalized with acute ischemic stroke.

Interpretation:

Increases in the prevalence of ischemic stroke hospitalizations and coexisting traditional stroke risk factors and health risk behaviors were identified among acute ischemic stroke hospitalizations in young adults. Our results from national surveillance data accentuate the need for public health initiatives to reduce risk factors for stroke among adolescents and young adults. ANN NEUROL 2011;
Dihydropyridine calcium channel blockers and the progression of parkinsonism
Authors: Marras Connie , Gruneir Andrea , Rochon Paula , Wang Xuesong , Anderson Geoff , Brotchie Jonathan , Bell Chaim M. , Fox Susan , Austin Peter C.
Published: September 2011

Objective:

A study was undertaken to test the association between dihydropyridine calcium channel blocker use and the time to important milestones of disease progression among patients with parkinsonism.

Methods:

Data were obtained from Ontario's health care administrative databases. Within a cohort of hypertensive individuals older than 65 years who developed parkinsonism, we examined the effect of the length of exposure to less brain‐penetrant dihydropyridines (amlodipine) and more brain‐penetrant dihydropyridines (eg, nifedipine, felodipine) on parkinsonism milestones as measured by time to requiring drug treatment for parkinsonism, nursing home admission, and death.

Results:

Among 4,733 hypertensive individuals with parkinsonism, longer treatment with any dihydropyridine was associated with a decreased risk of each of the 3 outcomes. There was no difference, however, between amlodipine (adjusted hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.42–0.50 for initiation of drug treatment; HR, 0.68; 95% CI, 0.63–0.73 for application for nursing home admission; and HR, 0.75; 95% CI, 0.70–0.80 for death) and nonamlodipine dihydropyridines (adjusted HRs [95% CIs], 0.45 [0.39–0.53], 0.74 [0.67–0.81], and 0.74 [0.64–0.85] for the 3 milestones, respectively).

Interpretation:

We found no specific beneficial effect of treatment with brain‐penetrant dihydropyridines on delaying parkinsonism progression milestones. Dihydropyridine calcium channel blockers are unlikely to have a clinically significant effect on the course of parkinsonism, particularly Parkinson disease, in the doses used to treat hypertension. ANN NEUROL 2012;
Optic radiation tractography and vision in anterior temporal lobe resection
Authors: Winston Gavin P. , Daga Pankaj , Stretton Jason , Modat Marc , Symms Mark R. , McEvoy Andrew W. , Ourselin Sebastien , Duncan John S.
Published: September 2011

Objective:

Anterior temporal lobe resection (ATLR) is an effective treatment for refractory temporal lobe epilepsy but may result in a contralateral superior visual field deficit (VFD) that precludes driving in the seizure‐free patient. Diffusion tensor imaging (DTI) tractography can delineate the optic radiation preoperatively and stratify risk. It would be advantageous to incorporate display of tracts into interventional magnetic resonance imaging (MRI) to guide surgery.

Methods:

We studied 20 patients undergoing ATLR. Structural MRI scans, DTI, and visual fields were acquired before and 3 to 12 months following surgery. Tractography of the optic radiation was performed on preoperative images and propagated onto postoperative images. The anteroposterior extent of the damage to Meyer's loop was determined, and visual loss was quantified using Goldmann perimetry.

Results:

Twelve patients (60%) suffered a VFD (10–92% of upper quadrant; median, 39%). Image registration took <3 minutes and predicted that Meyer's loop was 4.4 to 18.7mm anterior to the resection margin in these patients, but 0.0 to 17.6mm behind the resection margin in the 8 patients without VFD. The extent of damage to Meyer's loop significantly correlated with the degree of VFD and explained 65% of the variance in this measure.

Interpretation:

The optic radiation can be accurately delineated by tractography and propagated onto postoperative images. The technique is fast enough to propagate accurate preoperative tractography onto intraoperative scans acquired during neurosurgery, with the potential to reduce the risk of VFD. ANN NEUROL 2012;
Thermal stability and pyrolysis kinetics of lignin‐phenol‐formaldehyde resins
Authors: Pérez J. M. , Fernández A.
Published: September 2011

A thermal stability and kinetic study from non‐isothermal experiments of a commercial and a lignin‐novolac resin mixed with two amounts of curing agent has been done employing thermogravimetric analysis technique. Three kinetic models have been tested: a single heating rate method, such as Coats‐Redfern, employing several mechanistic functions and contrasted with Van Krevelen—it is the first time that this method has been employed in polymer degradation. Finally, the Ozawa method allowed the obtaining of the activation energy by the multiple‐heating‐rate without knowing the mechanism. Results show that commercial mixtures of resins lose less weight than lignin‐novolac resins. The calculated kinetic parameters showed that Coats‐Redfern gives similar results to Van Krevelen, which means that these methods are adequate for novolac pyrolysis, and Ozawa shows activation energies in accordance with the last mentioned models. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Recycled‐disposable‐chopstick‐fiber‐reinforced polypropylene green composites
Authors: Shih Yeng‐Fong , Chen Po‐Wei , Wu Chin‐San , Huang Chien‐Ming , Hsieh Chi‐Fa
Published: September 2011

The utilization of disposable chopsticks is very popular in Taiwan, China, and Japan and is one of the major sources of waste in these countries. In this study, recycled disposable chopstick fiber was chemically modified. Subsequently, this modified fiber and polypropylene‐graft‐maleic anhydride were added to polypropylene (PP) to form novel fiber‐reinforced green composites. A heat‐deflection temperature (HDT) test showed an increase of approximately 81% for PP with the addition of 60‐phr fibers, and the HDT of the composite could reach up to 144.8°C. In addition, the tensile strength, Young's modulus, and impact strength were 66, 160.3, and 97.1%, respectively, when the composite material was 40‐phr fibers. Furthermore, this type of reinforced PP would be more environmentally friendly than an artificial‐additive‐reinforced one. It could also effectively reduce and reuse the waste of disposable chopsticks and lower the costs of the materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of a crosslinked system on the morphology and properties of TPVs based on PA/NBR
Authors: Fagundes Enio C. M. , Jacobi Marly A. Maldaner
Published: September 2011

The mechanical properties of thermoplastic vulcanizates (TPVs), depend strongly on their morphologies, which themselves depend on the properties of the primary polymers, the composition of the TPV, and the crosslink system and crosslink process. The morphology is defined during the dynamic vulcanization. This work deals with the study of the influence of crosslink systems on TPVs based on PA/NBR (copolyamide PA6/6‐6 and nitrile rubber) in a 40/60 composition. Dicumyl peroxide, bismaleimide, phenolic resin, a sulfur‐accelerated system, and dicumyl peroxide with two coagents were used as crosslinkers. TPVs were characterized by taking into account their mechanical strength, solvent resistance, compression set, and morphology. The curing system constituted by dicumyl peroxide and sulfur/bismaleimide as coagents resulted in a more defined morphology, and therefore the TPV exhibited the best properties. For these TPVs, a morphology consisting of spherical domains of rubber distributed homogeneously on the polyamide matrix could be observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigations of the tribological properties of carbon fabric reinforced phenolic polymer composites filled with several nanoparticles
Authors: Wang Qihua , Zhang Xinrui , Pei Xianqiang , Wang Tingmei
Published: September 2011

The carbon fabric composites filled with several nanoparticles were prepared by dip‐coating and hot press molding technique. The friction and wear behavior of the resulting composites were studied systematically using a block‐on‐ring arrangement. Experimental results showed that the optimal content of nanoparticles as fillers contributed to improve the tribological properties of the carbon fabric composites. Moreover, the friction and wear properties of the fabric composites were closely dependent with the sliding conditions. The differences in the transfer film formed on the counterpart surface during the friction process also accounted for the friction and wear behavior of carbon fabric composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A convenient scheme for synthesizing reduction‐sensitive chitosan‐based amphiphilic copolymers for drug delivery
Authors: Moyuan Cao , Haixia Jin , Weijuan Ye , Peng Liu , Liqun Wang , Hongliang Jiang
Published: September 2011

A novel type of reduction‐sensitive graft copolymers, chitosan‐S‐S‐poly(ε‐caprolactone) (CS‐S‐S‐PCL, here ‐S‐S‐ means PCL was conjugated onto chitosan backbone through disulfide linkage), was synthesized through a convenient route using dithiodipropionic anhydride (DTDPA) as a disulfide donor. Reaction of hydroxy‐terminated poly(ε‐caprolactone) (PCL) with DTDPA quantitatively yielded DTDPA functionalized PCL (PCL‐S‐S‐COOH). The disulfide‐containing polyester was regioselectively conjugated onto the hydroxy groups of chitosan under mild and homogeneous conditions, utilizing dodecyl sulfate‐chitosan complexes (SCC) as an intermediate. The self‐assembly and Doxorubicin (Dox) release behavior of the copolymers were investigated. Spherical micelles could be formed through self‐assembly of CS‐S‐S‐PCL in aqueous media. The reduction‐sensitive behavior of CS‐S‐S‐PCL micelles was investigated by using Dithiothreitol (DTT) as a reductive reagent. In the presence of 10 mM DTT, the micelles gradually lost their aggregation stability and were precipitated out after four days. In addition, the Dox release was accelerated when the micelles were treated with DTT. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation of acrylic/acrylate copolymeric surfactants by emulsion polymerization used in pesticide oil‐in‐water emulsions
Authors: Shi Yongli , Zheng Ting , Shang Qing
Published: September 2011

In this work, acrylic/acrylate copolymeric surfactants, which can be used in the preparation of pesticide oil‐in‐water emulsions (EW), were synthesized by emulsion polymerization, using potassium persulfate (K2S2O8) as an initiator, dodecyl mercaptan (DDM) as a chain transfer agent at the temperature range of 82–85°C. When the weight ratio of monomers was m(butyl acrylate) : m(methyl methacrylate) : m(acrylic acid) = 4 : 4 : 1.6 and the dosage of DDM was 2% (percentage of monomer mass), the prepared acrylic/acrylate copolymeric surfactants had a number‐average molecular weight of 2.5 × 104 and exhibited good stability for pesticide EW. The carboxylic group distribution studies show that only the surface carboxylic groups make dispersed pesticide oil droplets more stable. The acrylic/acrylate copolymeric surfactants prepared by shot‐monomer had the most surface carboxylic group distribution (46.6%). To obtain greater surface carboxylic group distribution, maleic anhydride (MA) was used to modify the polymer system. Adding 2% MA (percentage of monomer mass) to the polymerization system, the surface carboxylic groups were increased 12% over unmodified acrylic/acrylate copolymeric surfactants. Compared with traditional pesticide EW, the avermectin EW prepared with acrylic/acrylate polymeric surfactant had much better stability. Meanwhile, its pesticide effect was similar to that of a control (1.8% abamectin emulsifiable solution). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Design, Synthesis, and Polymerase‐Catalyzed Incorporation of Click‐Modified Boronic Acid–TTP Analogues
Authors: Cheng Yunfeng , Dai Chaofeng , Peng Hanjing , Zheng Shilong , Jin Shan , Wang Binghe
Published: September 2011

DNA molecules are known to be important materials in sensing, aptamer selection, nanocomputing, and construction of unique architectures. The incorporation of modified nucleobases affords unique DNA properties for applications in areas that would otherwise be difficult or not possible. Earlier, we demonstrated that the boronic acid moiety can be introduced into DNA through polymerase‐catalyzed reactions. In order to study whether such incorporation by polymerase is a general phenomenon, we designed and synthesized four boronic acid‐modified thymidine triphosphate (TTP) analogues. The synthesis of certain analogues was through the use of a single dialkyne tether for both the Sonogashira coupling with thymidine and the later Cu‐mediated [3+2] cycloaddition for linking the boronic acid moiety. This approach is much more efficient than the previously described method, and paves the way for the preparation of a large number of boronic acid‐modified TTPs with a diverse set of structural features. All analogues showed very good stability under polymerase chain reaction (PCR) conditions and were recognized as a substrate by DNA polymerase, and thus incorporated into DNA.
Construction of Polymer–Protein Bioconjugates with Varying Chain Topologies: Polymer Molecular Weight and Steric Hindrance Effects
Authors: Wan Xuejuan , Zhang Guoying , Ge Zhishen , Narain Ravin , Liu Shiyong
Published: September 2011

We report on the fabrication of well‐defined polymer–protein bioconjugates with varying chain architectures, including star polymers, star block copolymers, and heteroarm star copolymers through the specific noncovalent interaction between avidin and biotinylated synthetic polymer precursors. Homopolymer and diblock precursors site‐specifically labeled with a single biotin moiety at the chain terminal, chain middle, or diblock junction point were synthesized by a combination of atom‐transfer radical polymerization (ATRP) and click reactions. By taking advantage of molecular recognition between avidin and biotin moieties, supramolecular star polymers, star block copolymers, and heteroarm star copolymers were successfully fabricated. This specific binding process was also assessed by using the diffraction optic technology (DOT) technique. We further investigated the effects of polymer molecular weights, location of biotin functionality within the polymer chain, and polymer chain conformations, that is, steric hindrance effects, on the binding numbers of biotinylated polymer chains per avidin within the polymer–protein bioconjugates, which were determined by the standard avidin/2‐(4‐hydroxyazobenzene)benzoic acid (HABA) assay. The binding numbers vary in the range of 1.9–3.3, depending on the molecular weights, locations of biotin functionality within synthetic polymer precursors, and polymer chain conformations.
A Bayesian approach to term structure modeling using heavy‐tailed distributions
Authors: Abanto‐Valle Carlos Antonio , Lachos Victor H. , Ghosh Pulak
Published: September 2011

In this paper, we introduce a robust extension of the three‐factor model of Diebold and Li (J. Econometrics, 130: 337–364, 2006) using the class of symmetric scale mixtures of normal distributions. Specific distributions examined include the multivariate normal, Student‐t, slash, and variance gamma distributions. In the presence of non‐normality in the data, these distributions provide an appealing robust alternative to the routine use of the normal distribution. Using a Bayesian paradigm, we developed an efficient MCMC algorithm for parameter estimation. Moreover, the mixing parameters obtained as a by‐product of the scale mixture representation can be used to identify outliers. Our results reveal that the Diebold–Li models based on the Student‐t and slash distributions provide significant improvement in in‐sample fit and out‐of‐sample forecast to the US yield data than the usual normal‐based model. Copyright © 2011 John Wiley & Sons, Ltd.
Setzungsnachweis für den Lastfall Erdbeben am Beispiel eines Kühlturmes am Arabischen Golf
Authors: Gödecke Jörg‐Henrik , Gödecke Heinz‐Joachim , Viedenz Ulrich
Published: September 2011

Erdbebenerschütterungen können insbesondere bei hochstehendem Grundwasser in sandigen Gründungsböden zur Bodenverflüssigung führen und erhebliche Setzungen verursachen, im ungünstigsten Fall bis zum Grundbruchversagen der gesamten Bauwerksgründung. Nachfolgend wird vom Bau einer setzungsempfindlichen flach gegründeten Kühlturmschale am Arabischen Golf mitsamt dem Setzungsnachweis für die Erdbebeneinwirkung berichtet.

Settlement analysis for the load case earthquake using the example of a cooling tower at the Arabian Peninsula. Earthquakes particularly in case of high ground water tables in sandy foundation soils could lead to liquefaction and cause severe settlements, resulting as a worst case scenario in a shear failure of the complete building foundation. In the following about the shallow foundation of a settlement sensitive shell structure of a cooling tower at the Arabian Peninsula will be reported and about the related settlement analysis for the load case earthquake.
Abschätzung der dynamischen Kenngrößen nichtbindiger Böden anhand der Korngrößenverteilungskurve
Authors: Wichtmann Torsten , Triantafyllidis Theodoros
Published: September 2011

Die gebräuchlichen empirischen Gleichungen für bodendynamische Kenngrößen wurden für gleichförmige Sande entwickelt und berücksichtigen den Einfluss der Korngrößenverteilungskurve nicht. Ihre Anwendung kann zu einer deutlichen Überschätzung des Schubmoduls ungleichförmiger Böden führen. Zur Erweiterung verschiedener empirischer Gleichungen um den Einfluss der Korngrößenverteilungskurve wurden ca. 650 Resonanzsäulenversuche an 65 speziell gemischten Korngrößenverteilungskurven eines Quarzsandes durchgeführt. Für jede Sandmischung wurden unterschiedliche Anfangslagerungsdichten, Drücke und Scherdehnungsamplituden getestet. In den Versuchen wurde u. a. eine deutliche Abnahme des Schubmoduls Gmax bei kleinen Dehnungsamplituden mit der Ungleichförmigkeitszahl Cu = d60/d10 und mit dem Feinkornanteil gemessen. Der mittlere Korndurchmesser hingegen hat kaum einen Einfluss auf die bodendynamischen Kenngrößen. Es kann gezeigt werden, dass die erweiterten empirischen Gleichungen nicht nur für lineare, sondern auch für abschnittsweise lineare, intermittierend gestufte und S‐förmige Korngrößenverteilungskurven zutreffende Prognosen liefern. Im Vergleich zu den bisher in der Praxis verwendeten Formeln sollten die erweiterten empirischen Gleichungen eine zuverlässigere Abschätzung der dynamischen Kenngrößen ermöglichen.

Estimating dynamic properties of granular soils under consideration of the grain size distribution curve. The common empirical formulas for dynamic soil parameters were developed for uniform sands and do not consider the influence of the grain size distribution curve. The application of these formulas can lead to a considerable overestimation of the shear modulus of well‐graded granular soils. 650 resonant column tests on 65 specially mixed grain size distribution curves of a quartz sand have been performed in order to extend various empirical equations by the influence of the grain size distribution curve. For each sand mixture different initial densities, pressures and shear strain amplitudes have been tested. Amongst others, a considerable decrease of the small‐strain shear modulus Gmax with increasing coefficient of uniformity Cu = d60/d10 and increasing fines content was measured. In contrast, mean grain size has nearly no influence on dynamic soil parameters. A good prediction of the extended empirical equations can be demonstrated not only for linear, but also for stepwise linear, gap‐graded and S‐shaped grain size distribution curves. In comparison to the empirical formulas applied so far, the new extended empirical equations should deliver a more reliable estimation of dynamic soil properties.
Latent variable modeling paradigms for genotype‐trait association studies
Authors: Liu Yan , Foulkes Andrea S.
Published: September 2011

Characterizing associations among multiple single‐nucleotide polymorphisms (SNPs) within and across genes, and measures of disease progression or disease status will potentially offer new insight into disease etiology and disease progression. However, this presents a significant analytic challenge due to the existence of multiple potentially informative genetic loci, as well as environmental and demographic factors, and the generally uncharacterized and complex relationships among them. Latent variable modeling approaches offer a natural framework for analysis of data arising from these population‐based genetic association investigations of complex diseases as they are well‐suited to uncover simultaneous effects of multiple markers. In this manuscript we describe application and performance of two such latent variable methods, namely structural equation models (SEMs) and mixed effects models (MEMs), and highlight their theoretical overlap. The relative advantages of each paradigm are investigated through simulation studies and, finally, an application to data arising from a study of anti‐retroviral‐associated dyslipidemia in HIV‐infected individuals is provided for illustration.
Guest‐Release Control in Enzyme‐Sensitive, Amphiphilic‐Dendrimer‐Based Nanoparticles through Photochemical Crosslinking
Authors: Raghupathi Krishna R. , Azagarsamy Malar A. , Thayumanavan S.
Published: September 2011

Stimuli sensitive, facially amphiphilic dendrimers have been synthesized and their enzyme‐responsive nature has been determined with dual fluorescence responses of both covalently conjugated and non‐covalently bound reporter units. These dual responses are correlated to ascertain the effect of enzymatic action on micellar aggregates and the consequential guest release. The release of the guest molecule is conveniently tuned by stabilizing the micellar aggregates through photochemical crosslinking of hydrophobic coumarin units. This photo‐crosslinking is also utilized as a tool to investigate the mode of enzyme–substrate interaction in the context of aggregate–monomer equilibrium.
An Efficient, Overall [4+1] Cycloadditon of 1,3‐Dienes and Nitrene Precursors
Authors: Wu Qiong , Hu Jian , Ren Xinfeng , Zhou Jianrong (Steve)
Published: September 2011

Intermolecular cycloadditions of conjugated dienes and nitrene precursors usually produce aziridines. A generally useful method was lacking to directly provide the [4+1] cycloadducts, 3‐pyrrolines. We have realized this transformation by using an uniquely active catalyst, copper(II) 1,1,1,5,5,5‐hexafluoroacetylacetonate ([Cu(hfacac)2]). The method is applicable to a wide array of dienes with good yields. When 1,4‐disubsituted dienes are used as substrates, good‐to‐excellent cis or trans selectivity can be obtained. Interestingly, the cis or trans preference depends on the nature of the substituents, rather than diene geometry. Mechanistic studies reveal that the [4+1] cycloaddition proceeds through diene aziridination and subsequent ring expansion. Among common copper catalysts, only [Cu(hfacac)2] can efficiently catalyze both steps, which explains the unique efficiency of the catalyst.
BINAP versus BINAP(O) in Asymmetric Intermolecular Mizoroki–Heck Reactions: Substantial Effects on Selectivities
Authors: Wöste Thorsten H. , Oestreich Martin
Published: September 2011

2,2′‐Bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP) was employed as chiral ligand in the enantioselective intermolecular Mizoroki–Heck reaction, whereas the use of cognate BINAP(O) (monooxidized BINAP) is unprecedented. The regio‐ and enantioselectivity of the arylation of representative cyclic alkenes changes dramatically in the presence of hemilabile BINAP(O) instead of BINAP. The arylation of 2,3‐dihydrofuran is perfectly regiodivergent (98:2 versus 0:100) and the arylation of cyclopentene is only enantioselective with BINAP(O) [60 versus 10 % enantiomeric excess (ee)]. Use of [Pd2(dba)3]⋅dba (dba=dibenzylideneacetone) instead of Pd(OAc)2 produces as high as 86 % ee in the arylation of cyclopentene.
Farewell, with gratitude
Authors: Pollock Raphael E.
Published: September 2011

Dr. Raphael Pollock welcomes a new Editor‐in‐Chief and bids Cancer farewell.
β‐Sheet‐Induced Chirogenesis in Polymerization of Oligopeptides
Authors: Wagner Nathaniel , Rubinov Boris , Ashkenasy Gonen
Published: September 2011

The origin of long homochiral biopolymers in living systems has recently been the focus of intense research. In one particular research line, scientists studied, experimentally and theoretically, chiral amplification obtained during peptide formation by polymerization of amino acid building blocks. It was suggested that processes leading to temporal or spatial separation, and thus, to the growth of homochiral polymers at the expense of their heterochiral counterparts, can explain the chirality observed in larger molecules. We introduce a simple model and stochastic simulation for the polymerization of amino acids and β‐sheet formation, showing the crucial effects of the β sheets on the distributions of peptide lengths. When chiral affinities are included, racemic β sheets of alternating homochiral strands lead to the formation of chiral peptides, the isotacticity of which increases with length, consistent with previous experimental results in aqueous solutions. The tendency to form isotactic peptides is shown for both initially racemic and initially nonracemic systems, as well as for closed and open systems. We suggest that these or similar mechanisms may explain the origin of chiroselectivity in prebiotic environments.
Evaluating the effectiveness and efficacy of unguided internet‐based self‐help intervention for the prevention of depression: a randomized controlled trial
Authors: Lintvedt Ove K. , Griffiths Kathleen M. , Sørensen Kristian , Østvik Andreas R. , Wang Catharina E. A. , Eisemann Martin , Waterloo Knut
Published: September 2011

The Internet has the potential to increase the capacity and accessibility of mental health services. This study aimed to investigate whether an unguided Internet‐based self‐help intervention delivered without human support or guidance can reduce symptoms of depression in young people at risk of depression. The study also aimed to explore the usage of such sites in a real‐life setting, to estimate the effects of the intervention for those who received a meaningful intervention dose and to evaluate user satisfaction. Young adults were recruited by means of a screening survey sent to all students at the University of Tromsø. Of those responding to the survey, 163 students (mean age 28.2 years) with elevated psychological distress were recruited to the trial and randomized to an Internet intervention condition or the waiting list control group. The Internet condition comprised a depression information website and a self‐help Web application delivering automated cognitive behavioural therapy. The participants in the waiting list condition were free to access formal or informal help as usual. Two‐thirds of the users who completed the trial initially reported an unmet need for help. The findings demonstrated that an unguided intervention was effective in reducing symptoms of depression and negative thoughts and in increasing depression literacy in young adults. Significant improvements were found at 2‐month follow up. Internet‐based interventions can be effective without tracking and thus constitute a minimal cost intervention for reaching a large number of people. User satisfaction among participants was high. Copyright © 2011 John Wiley & Sons, Ltd.

Key Practitioner Message

Internet‐based self‐help can be useful for early intervention among people experiencing elevated depressive symptoms.

The present trial demonstrated that an unguided intervention can be effective in reducing depressive symptoms.

The Internet‐based intervention has the potential of reaching a target group with an unmet need for help.

Approximately 27% of users referred to the site completed on average 55% of the intervention.
Hypomanic Personality, Stability of Self‐Esteem and Response Styles to Negative Mood
Authors: Bentall Richard P. , Myin‐Germeys Inez , Smith Angela , Knowles Rebecca , Jones Steven H. , Smith Talya , Tai Sara J.
Published: September 2011

Objectives

This paper aims to study dysfunctional self‐schematic processes, abnormal coping styles, over‐responsiveness to reward stimuli (indicative of an over‐sensitive behavioural activation system) and stability of self‐esteem in relation to subclinical hypomania.

Design

Three cross‐sectional studies were conducted on selected students on the basis of their scores on the Hypomanic Personality Scale (HPS) (study 1) and on elevated HPS and Dysfunctional Attitude Scale scores (studies 2 and 3).

Methods

In studies 1 and 2, participants completed questionnaires and kept a self‐esteem diary for 6 days. In study 3, the experience sampling method was used to assess momentary self‐esteem, emotion and use of different coping styles over a 6‐day period.

Results

Study 1 demonstrated that hypomanic traits are associated with high fluctuations in self‐esteem. In study 2, high scores on both the HPS and the Dysfunctional Attitude Scale, but not the HPS alone, were associated with bipolar spectrum symptoms. These participants showed more evidence of alcohol and substance abuse, greater self‐esteem fluctuation and dysfunctional coping styles (rumination and risk‐taking) compared with controls. Changes in self‐esteem were related to the use of these strategies.

Conclusions

Vulnerability to bipolar disorder is associated with a combination of depression‐related and reward‐related processes. Copyright © 2011 John Wiley & Sons, Ltd.
Chemical Vapor Synthesis and Characterization of Manganese Oxides
Authors: Le Hoang Anh , Chin Sungmin , Park Eunseuk , Linh Le Thuy , Bae Gwi‐Nam , Jurng Jongsoo
Published: September 2011

Manganese oxide nanoparticles are synthesized by a chemical vapor process using manganese(0) carbonyl as the precursor. The synthesis temperature of the materials is varied from 500 to 1500 °C at 200 °C intervals. These nanomaterials are characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer‐Emmett‐Teller (BET) surface area, and X‐ray photoelectron spectroscopy (XPS). XRD shows that the manganese oxide nanoparticles synthesized at 500, 700 – 1100, 1300, and 1500 °C are mainly MnO2, Mn2O3, Mn2O3/Mn3O4, and Mn3O4, respectively. The TEM and BET results also confirm that the particle size is on the nanometer scale with a large specific surface area (SSA) of 81 – 215 m2 g−1. XPS indicates the catalysts to have manganese oxidation states of (2+), (3+), or (4+) depending on the synthesis temperature.
CVD of Poly(α,α′‐dimethyl‐p‐xylylene) and Poly(α,α,α′,α′‐tetramethyl‐p‐xylylene)‐co‐poly(p‐xylylene) from Alkoxide Precursors II: Thermal Oxidative Stability
Authors: Senkevich Jay J.
Published: September 2011

The Achilles heel of the parylene polymers is their oxidative stability at room temperature with UV exposure and at elevated temperature >115 °C in air. This weakness is attributed to the aliphatic carbon‐carbon single bond in the main‐chain backbone. Fluorinating this chemistry helps the oxidation substantially, but the precursor then becomes nearly prohibitive to use due to cost of the precursor and the processing cost. Another option is to explore the methylation of this benzyl position. Poly(α,α′‐dimethyl‐p‐xylylene) and poly(α,α,α′,α′‐tetramethyl‐p‐xylylene)‐co‐poly(p‐xylylene) are deposited on the parylene platform via alkoxy precursors. Their oxidation as a function of temperature to 300 °C; and time at 150 °C is explored via variable angle spectroscopic ellipsometry (VASE) and infrared spectroscopy (IRS). Results show very little difference between the two polymers as a function of oxidation temperature, and better results compared to what was previously observed with the poly(p‐xylylene) homopolymer, however the oxidation of poly(α,α′‐dimethyl‐p‐xylylene) at 150 °C as a function of time is less positive with 16% thickness loss over 1000 h with the post‐deposition annealed sample.
Matrix Infrared Spectroscopy and a Theoretical Investigation of SUO and US2
Authors: Andrews Lester , Wang Xuefeng , Liang Binyong , Ruipérez Fernando , Infante Ivan , Raw Adam D. , Ibers James A.
Published: September 2011

US2 and SUO molecules have been prepared by laser ablation of the solid materials and reaction of the elements during condensation in solid argon, which give the same absorptions as earlier U atom reactions with sulfur vapor and sulfur dioxide. The antisymmetric stretching mode of US2 shifts from 438.7 cm–1 in solid argon to 442.3 cm–1 in solid neon, which shows that the same electronic state is trapped in both matrix environments. Density functional calculations find a bent (3B2) ground state for the US2 molecule, and CASSCF/CASPT2 calculations reveal a multiconfigurational mixture of (5fφ)1(5fδ)1‐type states, whereas the most stable state for UO2 is a linear structure of the (5fφ)(7s) type. The bent triplet ground state SUO molecule exhibits similar multireference character with the U–O stretching mode at 857.1 cm–1 in solid argon. The linear SUO molecule computed at the CASPT2 level is only 2 kcal/mol above the bent structure. A detailed analysis of the bonding in US2 and SUO is provided and compared to the better known UO2 molecule.
The Bromodiazirinyl Anion: A Weakly Bound Complex of Diazirinylidene and a Bromide Ion
Authors: Martinů Tomáš , Böhm Stanislav , Hanzlová Eva
Published: September 2011

Experimental and computational evidence suggests that the cleavage of n‐butyl and tert‐butyl 3‐bromodiazirine‐3‐carboxylates by sodium n‐butoxide in DMF, affording high yields of dibutyl carbonates, may proceed by nucleophilic acyl displacement of the bromodiazirinyl anion, a weakly bound complex of a cyclic carbene c‐CN2 (diazirinylidene) and a bromide ion. We explain the formation of substantial amounts of di‐n‐butoxymethane in the presence of n‐butanol by a sequence of O–H insertion and denitrogenation reactions of the putative c‐CN2 carbene. This ground‐state singlet species is the last undescribed member of the CN2 family of reactive intermediates. It differs from classical N‐heterocyclic carbenes by its high ionization potential and electron affinity.