bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining Oxidative N‐Heterocyclic Carbene Catalysis with Click Chemistry: A Facile One‐Pot Approach to 1,2,3‐Triazole Derivatives
Authors: Ramanjaneyulu B. T. , Reddy Virsinha , Arde Panjab , Mahesh Sriram , Anand R. Vijaya
Published: April 2013

A combination of the oxidative N‐heterocyclic carbene catalysis and click chemistry has been explored for the direct, one‐pot synthesis of 1,2,3‐triazole derivatives from aromatic aldehydes. This procedure was found to be very efficient and a variety of 1,2,3‐triazole derivatives could be accessed through their corresponding propargyl esters in moderate‐to‐good yields under mild conditions.
Synthesis, Physical Properties, and Anion Recognition of Two Novel Larger Azaacenes: Benzannelated Hexazaheptacene and Benzannelated N,N′‐Dihydrohexazaheptacene
Authors: Li Gang , Wu Yuechao , Gao Junkuo , Li Junbo , Zhao Yang , Zhang Qichun
Published: April 2013

Two novel larger azaacenes with six or ten N atoms in their backbones, benzannelated 9,11,13,22,24,26‐hexazatetrabenzo[a,c,l,n]heptacene (HATBH, 1) and benzannelated 9,26‐dihydro‐9,11,13,22,24,26‐hexaza‐tetrapyrido[3,2‐a: 2′,3′‐c: 3′′,2′′‐l: 2′′′,3′′′‐n]heptacene (DHATPH, 2), have been successfully synthesized in two steps. The theoretical band gaps estimated through DFT calculations for HATBH (1) and DHATPH (2) are 1.949 eV and 2.278 eV, which are close to the experimentally obtained optical band gaps (2.14 eV and 2.39 eV). Interestingly, HATBH (1) can act as efficient anion sensor for F− and H2PO4−, while DHATPH (2) selectively responds to F− among the ten different anions used (F−, Cl−, Br−, I−, PF6−, HSO4−, NO3−, BF4−, AcO−, and H2PO4−). Our synthetic strategy could offer a promising and easy way to obtain even larger azaacenes.
Evaluation of vanillic acid as inhibitor of carbonic anhydrase isozyme III by using a modified Hummel–Dreyer method: approach for drug discovery
Authors: Alzweiri Muhammed , Al‐Hiari Yusuf
Published: April 2013

α‐3 carbonic anhydrase isozyme (CAIII) is the most abundant protein in adipocytes and considered insensitive to sulfonamide inhibitors. It was reported recently that the knock‐down of CAIII is attributed with controlling lipogenesis. Thus inhibition of this target may lead to the discovery of new therapies against obesity and insulin resistance. Vanillic acid as a small molecule with coordinating groups and has a potential to bind zinc atoms in CA binding sites. Inhibition of CAIII by vanillic acid was evaluated by Hummel–Dreyer chromatography because it provides free interaction between ligand and macromolecule and introduces solution for faulty results obtained by current colorimetric assays. HPLC system of vanillic acid produces vacancy (negative) peak representing the amount of attached vanillic acid with CAIII. It was found that vanillic acid is able to bind with CAIII through two equilibria, one at equimolar ratio and another at 2:1 (vanillic acid–CAIII) ratio. The affinity constant of equimolar binding between CAIII and vanillic acid was found to be 14,400 m−1. It was found that vanillic acid binding with CAIII is much stronger than phenol and acetazolamide (positive controls). Copyright © 2013 John Wiley & Sons, Ltd.
A fast polygon inflation algorithm to compute the area of feasible solutions for three‐component systems. I: concepts and applications
Authors: Sawall Mathias , Kubis Christoph , Selent Detlef , Börner Armin , Neymeyr Klaus
Published: April 2013

The multicomponent factorization of multivariate data often results in nonunique solutions. The so‐called rotational ambiguity paraphrases the existence of multiple solutions that can be represented by the area of feasible solutions (AFS). The AFS is a bounded set that may consist of isolated subsets. The numerical computation of the AFS is well understood for two‐component systems and is an expensive numerical process for three‐component systems. In this paper, a new fast and accurate algorithm is suggested that is based on the inflation of polygons. Starting with an initial triangle located in a topologically connected subset of the AFS, an automatic extrusion algorithm is used to form a sequence of growing polygons that approximate the AFS from the interior. The polygon inflation algorithm can be generalized to systems with more than three components. The efficiency of this algorithm is demonstrated for a model problem including noise and a multicomponent chemical reaction system. Further, the method is compared with the recent triangle‐boundary‐enclosing scheme of Golshan, Abdollahi, and Maeder (Anal. Chem. 2011, 83, 836–841). Copyright © 2013 John Wiley & Sons, Ltd.
Enantioselective Synthesis of Alcohols and Amines by Iridium‐Catalyzed Hydrogenation, Transfer Hydrogenation, and Related Processes
Authors: Bartoszewicz Agnieszka , Ahlsten Nanna , Martín‐Matute Belén
Published: April 2013

The preparation of chiral alcohols and amines by using iridium catalysis is reviewed. The methods presented include the reduction of ketones or imines by using hydrogen (hydrogenations), isopropanol, formic acid, or formate (transfer hydrogenations). Also dynamic and oxidative kinetic resolutions leading to chiral alcohols and amines are included. Selected literature reports from early contributions to December 2012 are discussed.
Synthesis of 8‐Desmethoxy Psymberin: A Putative Biosynthetic Intermediate Towards the Marine Polyketide Psymberin
Authors: Bielitza Max , Pietruszka Jörg
Published: April 2013

The synthesis of a putative biosynthetic precursor of psymberin including a formal synthesis of the natural product is described. The key step towards the densely functionalized tetrahydropyran core was an enantioselective catalytic Mukaiyama aldol reaction using a titanium(IV)–BINOL catalyst system. syn‐Selective reduction followed by ozonolysis led to a rapid assembly of the tetrahydropyran ring. This flexible approach also allows the synthesis of similar fragments of other complex molecules such as bryostatins and pederins. The syn‐selective coupling between the tetrahydropyran and the aromatic aldehyde was achieved using a boron‐mediated aldol reaction which was followed by further transformations to complete the synthesis of the precursor as well as the formal synthesis of the natural product.
Separation of CO2 and CH4 on CaX zeolite for use in Landfill gas separation
Authors: Oddy Sarah , Poupore Jessica , Tezel F. Handan
Published: April 2013

In this study, adsorption separation of main components of landfill gas, methane (CH4) and carbon dioxide (CO2) was carried out. Henry's law constants, limiting heat of adsorption values, pure and binary isotherms for CO2 and CH4 were determined for CaX zeolite adsorbent. Pure isotherm data were compared to those for NaX zeolite from previous studies. The CO2 adsorption capacity of CaX was greater than that of NaX; however, NaX's separation factor was higher. The heat of adsorption for CO2 for CaX was higher than those for NaX. © 2013 Canadian Society for Chemical Engineering
Experimental evidence of low rayleigh vibration on mixture during thermodiffusion experiment
Authors: Kianian Armin , Ahadi Amirhossein , Saghir M. Ziad
Published: April 2013

This paper demonstrates the influence of low Rayleigh vibration on thermodiffusion measurement in microgravity environment. The goal is to show how the variation of certain parameters such as frequency and amplitude of translational vibrations would impact the results obtained from the ISS experiment. Precisely, impact of change in low Rayleigh vibration on the separation of a component is studied for each experimental run.

ISS experimental data are obtained based on optical digital interferometry in a reduced gravity environment. The experiment is done in a cubic cell containing an aqueous solution exposed to a lateral temperature gradient. A mixture of water and isopropanol of different initial concentrations with positive and negative Soret coefficient is chosen as the test fluid. Collected data are analysed by image processing. Results show maximum separation of components for the case without any forced vibration. Moreover, an increase in Rayleigh number corresponds to decrease in the separation of components.
Clinical features, presentation, and tolerance of platinum‐based chemotherapy in germ cell tumor patients 50 years of age and older
Authors: Feldman Darren R. , Voss Martin H. , Jacobsen Erin P. , Jia Xiaoyu , Suarez J. Andres , Turkula Stefan , Sheinfeld Joel , Bosl George J. , Motzer Robert J. , Patil Sujata
Published: April 2013

BACKGROUND

Germ cell tumors (GCTs) primarily affect adolescent and young adult men. Detailed clinical and treatment characteristics in older men are lacking.

METHODS

Patients with GCT seen over a 20‐year period at Memorial Sloan‐Kettering Cancer Center were identified. Primary tumor site and histology were compared for patients aged ≥ 50 years at diagnosis versus younger men. For patients aged ≥ 50, individual chart review was performed and treatment delays, changes, and toxicities were recorded for those treated with first‐line chemotherapy.

RESULTS

Of 4235 diagnoses of GCT, 3999 (94.4%) were made at age < 50 versus 236 (5.6%) at age ≥ 50. Compared with patients diagnosed before age 50, older men more frequently had seminoma (62.7% versus 36.7%) and less frequently, nonseminoma (34.7% versus 63.2%) (P < .0001). Predominant histology switched from nonseminoma to seminoma around age 35. Distribution of primary sites also differed for older versus younger men (testis: 89.4% versus 92.9%; retroperitoneal: 3.8% versus 0.7%; CNS 0% versus 1.7%) except for mediastinal primary tumors, which remained constant across age groups. Fifty patients age ≥ 50 received first‐line platinum‐based chemotherapy; 30 experienced complications leading to treatment discontinuation, delay ≥ 7 days, or regimen change. Twenty‐two (44%) patients experienced neutropenic fever, 6 despite prophylactic growth factor support. Estimated 5‐year survival for chemotherapy‐treated patients was 84.9%.

CONCLUSIONS

Men aged ≥ 50 years comprise less than 10% of GCT diagnoses and have distinct clinical and histological characteristics as compared with younger patients. Although complications from chemotherapy occur frequently in older men, prognosis remains excellent when risk‐directed treatment is administered with curative intent. Cancer 2013;119:2574–2581. © 2013 American Cancer Society.
Matched‐pair and propensity score comparisons of outcomes of patients with clinical stage I non–small cell lung cancer treated with resection or stereotactic radiosurgery
Authors: Varlotto John , Fakiris Achilles , Flickinger John , Medford‐Davis Laura , Liss Adam , Shelkey Julia , Belani Chandra , DeLuca Jill , Recht Abram , Maheshwari Neelabh , Barriger Robert , Yao Nengliang , DeCamp Malcolm
Published: April 2013

BACKGROUND

Stereotactic body radiotherapy (SBRT) is an alternative to surgery for clinical stage I non–small cell lung cancer (NSCLC), but comparing its effectiveness is difficult because of differences in patient selection and staging.

METHODS

Two databases were combined which contained patients treated from 1999 to 2008 by lobectomy (LR, n = 132), sublobar resection (SLR, n = 48), and SBRT (n = 137) after negative staging. Univariate and multivariate analysis were performed for survival (OS), total recurrence control (TRC comprises local‐regional and distant control), and locoregional control (LRC) in our entire population. A matched‐pair analysis was also performed that compared surgery and SBRT results. Median follow‐up for the entire study population was 25.8 months.

RESULTS

On univariate analysis, OS was significantly worse with SBRT and also correlated with histology, the Charlson comorbidity index, tumor size, and aspirin use; TRC correlated only with histology; and no variable significantly correlated with LRC. OS was significantly poorer for SBRT in the matched‐pair analysis than for patients treated with surgery, but TRC and LRC were not significantly different between these groups. Multivariate analyses including propensity score as a covariate (controlling for all factors affecting treatment selection) found that OS correlated only with Charlson comorbidity index, and TRC correlated only with tumor grade. LRC correlated only with tumor size with or without propensity score correction.

CONCLUSIONS

This retrospective study has demonstrated similar OS, LRC, and TRC with SBRT or surgery after controlling for prognostic and patient selection factors. Randomized clinical trials are needed to better compare the effectiveness of these treatments. Cancer 2013;119:2683–2691. © 2013 American Cancer Society.
Cardiovascular and lung mesh generation based on centerlines
Authors: Marchandise E. , Geuzaine C. , Remacle J.F.
Published: April 2013

We present a fully automatic procedure for the mesh generation of tubular geometries such as blood vessels or airways. The procedure is implemented in the open‐source Gmsh software and relies on a centerline description of the input geometry. The presented method can generate different type of meshes: isotropic tetrahedral meshes, anisotropic tetrahedral meshes, and mixed hexahedral/tetrahedral meshes. Additionally, a multiple layered arterial wall can be generated with a variable thickness. All the generated meshes rely on a mesh size field and a mesh metric that is based on centerline descriptions, namely the distance to the centerlines and a local reference system based on the tangent and the normal directions to the centerlines. Different examples show that the proposed method is very efficient and robust and leads to high quality computational meshes. Copyright © 2013 John Wiley & Sons, Ltd.
In Situ Direct Measurement of Vapor Pressures and Thermodynamic Parameters of Volatile Organic Materials in the Vapor Phase: Benzoic Acid, Ferrocene, and Naphthalene
Authors: Hikal Walid M. , Weeks Brandon L.
Published: April 2013

We report the direct determination of vapor pressures and optical and thermodynamic parameters of powders of low‐volatile materials in their vapor phase using a commercial UV/Vis spectrometer. This methodology is based on the linear proportionality between the density of the saturated gas of the material and the absorbance of the gas at different temperatures. The vapor pressure values determined for benzoic acid and ferrocene are in good agreement with those reported in the literature with ∼2–7 % uncertainty. Thermodynamic parameters of benzoic acid, ferrocene, and naphthalene are determined in situ at temperatures below their melting points. The sublimation enthalpies of the investigated organic molecules are in excellent agreement with the ICTAC recommended values (less than 1 % difference). This method has been used to measure vapor pressures and thermodynamic parameters of organic volatile materials with vapor pressures of ∼0.5–355 Pa in the 50–100 °C temperature range.
Solar Power Conditioners Using Bidirectional Chopper Circuits Connected in Series
Authors: Fujita Hideaki , Mabuchi Masao , Tsubota Yasuhiro , Mizogami Takao
Published: April 2013

This paper proposes a new high‐efficiency grid‐connection inverter suitable for the interface with thin‐film solar cells, which is composed of two bidirectional buck converters and an H‐bridge PWM converter connected in series. The switching frequencies of the first bidirectional buck converters are equal to the grid frequency, while the second is operated at twice the grid frequency. The combination of these two converters synthesizes an AC rectangular voltage pulse train from the DC input power. The H‐bridge PWM converter is operated at 20 kHz with a low DC capacitor voltage to compensate for the harmonic voltage included in the rectangular voltage pulse train. As a result, the proposed grid‐connection inverter makes it possible to reduce both switching loss and common mode voltage. Experimental results obtained by a 1‐kW single‐phase inverter demonstrate a high efficiency of 98% without any common mode voltage. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(2): 51–60, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22379
Synthesis and Functionalization of Triply Fused Porphyrin Dimers
Authors: Ryan Aoife A. , Senge Mathias O.
Published: April 2013

Current applications of porphyrins in medicine and optics, such as photodynamic therapy or nonlinear absorption, increasingly require the use of far‐red absorbing dyes. Modification of the porphyrin structure to accommodate these conditions can be achieved by extending the conjugation of the porphyrin π system, which causes a bathochromic shift in the absorption spectrum. Thus, conjugated porphyrin oligomers have found widespread use. However, past synthetic strategies have mainly targeted symmetric porphyrin dimers, trimers, and oligomers which limit the practical use of such chromophores. To further extend the absorption profile, a series of symmetric and unsymmetric dimeric and oligomeric porphyrin β–β, meso–meso, β′–β′ triply fused systems were synthesized by oxidative coupling methods. This required an analysis and optimization of the various synthetic strategies. These arrays exhibit a dramatic bathochromic shift into the near‐infrared region and many display absorption at wavelengths greater than 1050 nm. Additionally, post‐fusing chemical transformations, namely, organolithium, cycloaddition, and transition‐metal‐catalyzed reactions, at the meso and β positions enable the fine‐tuning of such arrays to enhance the bathochromic shift and their potential optical applications.
Tautomerism in the Fused N‐Rich Tri­azolotriazole Heterocyclic System
Authors: Centore Roberto , Fusco Sandra , Capobianco Amedeo , Piccialli Vincenzo , Zaccaria Sabrina , Peluso Andrea
Published: April 2013

Tautomerism in the [1,2,4]triazolo[3,2‐c][1,2,4]triazole fused aromatic system has been investigated by single‐crystal X‐ray analysis, UV/Vis spectroscopy and theoretical calculations on selected new heterobicycle derivatives. The reactions of 3,4‐diamino‐1,2,4‐triazoles with acyl chlorides or acetic anhydride in pyridine at reflux led to ring closure and the fused aromatic system was obtained as the secondary amide at N2 instead of at N5 as previously reported in the literature. For the [1,2,4]triazolo[3,2‐c][1,2,4]triazole system, three different tautomers can be present. Crystal structure analysis showed the presence of only one tautomer or, depending on the packing, a mixture of two; theoretical calculations supported this finding, predicting that for all the investigated compounds one tautomer is energetically disfavoured with respect to the other two. The electronic absorption spectra of some compounds show a marked solvent dependence, which has been interpreted, with the help of theoretical calculations, in terms of acid/base equilibria, which are critically dependent upon the substituents at the heterobicycle.
Amphiphilic Cyclic Peptoids That Exhibit Antimicrobial Activity by Disrupting Staphylococcus aureus Membranes
Authors: Huang Mia L. , Benson Meredith A. , Shin Sung Bin Y. , Torres Victor J. , Kirshenbaum Kent
Published: April 2013

There is a significant unmet need for new antimicrobial agents that can address antimicrobial resistance. One promising group of antimicrobials is the antimicrobial peptides (AMPs) and their synthetic mimics. In particular, synthetic sequence‐specific oligomers of N‐substituted glycine, termed “peptoids”, have been found to show potent antimicrobial activity against bacterial pathogens in vitro and can act against the emergence of antimicrobial resistance. In this study, we evaluate the antimicrobial activity of cyclic peptoid oligomers against clinical isolates of methicillin‐resistant Staphylococcus aureus (MRSA). The presence of the macrocyclic constraints can enforce a globally amphiphilic organization of the peptoid side‐chains. Several of these new amphiphilic compounds show potent and selective antimicrobial activity. Electron microscopy experiments demonstrate that the peptoids target and damage the MRSA cytoplasmic membrane through the formation of pores. These results substantiate the potential of peptoids as antimicrobial therapeutic agents for the treatment of S. aureus infections.
Pillararenes: Versatile Synthetic Receptors for Supramolecular Chemistry
Authors: Ogoshi Tomoki , Yamagishi Tada‐aki
Published: April 2013

In 2008 we reported a new class of macrocyclic hosts that we named “pillararenes”. To date, pillar[5]arenes and pillar[6]arenes, containing five and six repeating units, respectively, have been synthesized. Pillar[5]arenes and pillar[6]arenes can accommodate 10 and 12 substituent groups, respectively. The position‐selective versatile functionalization of these substituents enables the preparation of various supramolecular assemblies. Here we discuss the synthesis and selective functionalization of pillararenes. We also discuss the use of the various pillararene derivatives as components of supramolecular assemblies such as sensors, a self‐inclusion complex, supramolecular dimers, polymers, an alternating polymer consisting of pillar[5]arene and pillar[6]arene units, systems in which pillararene shuttles along an axle, rotaxanes, polyrotaxanes, and pillar[5]arene‐based bulk‐materials, as well as colloidal assembly of pillararenes, biomedical applications, and hybridization with inorganic materials.
Three‐Component Tandem‐Intramolecular Hydroamination Reactions in One Pot Involving Indoles, 2‐Aminobenzyl Alcohols, and 2‐Alkynylbenzaldehydes: Consecutive 7‐endo‐trig and Electrophilic 6‐endo‐dig Cyclizations
Authors: Samala Srinivas , Saifuddin Mohammad , Mandadapu Anil K. , Kundu Bijoy
Published: April 2013

A one‐pot protocol for the synthesis of indole‐based annulated polyheterocycles involving consecutive 7‐endo‐trig and electrophilic 6‐endo‐dig cyclizations is described. The reaction proceeds initially through annulation of 5‐methoxyindole, 2‐amino benzyl alcohol and 2‐alkynylbenzaldehyde in a three‐component tandem manner to form benzazepino‐indole, which then undergoes a second consecutive ring closure through intramolecular hydroamination to yield isoquinolino‐benzazepino‐indoles hitherto not reported in the literature.
Schmidt hammer exposure‐age dating (SHD) of late Quaternary fluvial terraces in New Zealand
Authors: Stahl Timothy , Winkler Stefan , Quigley Mark , Bebbington Mark , Duffy Brendan , Duke Daniel
Published: April 2013

Schmidt hammer (SH) R‐values are reported for surface clasts from numerically dated Holocene and Pleistocene fluvial terraces in the South Island of New Zealand. The R‐values are combined with previously obtained weathering rind, radiocarbon, terrestrial cosmogenic nuclide and luminescence terrace ages to derive SH R‐value chronofunctions for greywacke clasts from four distinct locations. Our results show that different weathering rates affect the form of the SH R‐value versus Age curve, however a fundamental dependency between the two remains constant over timescales ranging from 102 to 105 years. Power law scaling constants suggest changes in clast weathering rates are primarily affected by climatic (precipitation and temperature) and sedimentologic variables (source terrane petrology). Age uncertainties of ~22% of the surface age suggest that Schmidt hammer exposure‐age dating (SHD) is a reliable calibrated‐age dating technique for fluvial terraces. Copyright © 2013 John Wiley & Sons, Ltd.
Association between depression and maintenance medication adherence among Medicare beneficiaries with chronic obstructive pulmonary disease
Authors: Qian Jingjing , Simoni‐Wastila Linda , Rattinger Gail B. , Zuckerman Ilene H. , Lehmann Susan , Wei Yu‐Jung J. , Stuart Bruce
Published: April 2013

Objective

Depression is a significant comorbidity in patients with chronic obstructive pulmonary disease (COPD). Although comorbid depression is associated with low use and poor adherence to medications treating other chronic conditions, evidence of the relationship between depression and COPD management is limited. This study estimated the association between depression and COPD maintenance medication (MM) adherence among patients with COPD.

Methods

This cross‐sectional study used a 5% random sample of 2006–2007 Chronic Condition Warehouse data. Medicare beneficiaries enrolled in Parts A, B, and D plans with diagnosed COPD who survived through 2006 were included (n = 74,863). COPD MM adherence was measured as medication discontinuation and proportion of days covered (PDC). Depression was identified through the International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. Multivariable models with modified generalized estimating equations were used to estimate adjusted association between depression diagnosis and medication adherence, controlling for sociodemographics, comorbidities, and disease severity.

Results

Among the sample, about one third (33.6%) had diagnosed depression. More than half (61.8%) of beneficiaries with COPD filled at least one COPD MM prescription. Depressed beneficiaries had a higher likelihood of using COPD MM than non‐depressed beneficiaries (adjusted prevalence ratios [PR] = 1.02; 95% confidence intervals [CI] = 1.01, 1.03). Among COPD MM users, depressed beneficiaries were more likely to discontinue medications (PR = 1.09; 95% CI = 1.04, 1.14) and less likely to exhibit PDC ≥ 0.80 (PR = 0.89; 95% CI = 0.86, 0.92) than non‐depressed beneficiaries.

Conclusions

Depression is prevalent in Medicare beneficiaries with COPD and independently associated with lower COPD MM adherence. Interventions to improve medication adherence for COPD patients may consider management of comorbidities such as depression. Copyright © 2013 John Wiley & Sons, Ltd.
Natural climate variability and teleconnections to precipitation over the Pacific‐North American region in CMIP3 and CMIP5 models
Authors: Polade Suraj D. , Gershunov Alexander , Cayan Daniel R. , Dettinger Michael D. , Pierce David W.
Published: April 2013

Natural climate variability will continue to be an important aspect of future regional climate even in the midst of long‐term secular changes. Consequently, the ability of climate models to simulate major natural modes of variability and their teleconnections provides important context for the interpretation and use of climate change projections. Comparisons reported here indicate that the CMIP5 generation of global climate models shows significant improvements in simulations of key Pacific climate mode and their teleconnections to North America compared to earlier CMIP3 simulations. The performance of 14 models with simulations in both the CMIP3 and CMIP5 archives are assessed using singular value decomposition analysis of simulated and observed winter Pacific sea surface temperatures (SSTs) and concurrent precipitation over the contiguous United States and northwestern Mexico. Most of the models reproduce basic features of the key natural mode and their teleconnections, albeit with notable regional deviations from observations in both SST and precipitation. Increasing horizontal resolution in the CMIP5 simulations is an important, but not a necessary, factor in the improvement from CMIP3 to CMIP5.
Rock varnish evidence for a Younger Dryas wet period in the Dead Sea basin
Authors: Liu Tanzhuo , Broecker Wallace S. , Stein Mordechai
Published: April 2013

Rock varnish from 14.6 to 13.2 ka recessional shorelines of late glacial Lake Lisan and fan delta surfaces between 280 and 365 m bmsl (meters below mean sea level) along the western margins of the Dead Sea contains replicable layering patterns, characterized by a low Mn and Ba orange/yellow surface layer and a high Mn and Ba dark basal layer. The deposition of the dark basal layers immediately after the lake recession represents a wet period coinciding with the Younger Dryas (YD) cooling (12.9–11.6 ka), manifesting the influence of midlatitude westerly winds in the eastern Mediterranean‐central Levant (EM‐CL). In contrast, varnish from the distal base of fan deltas contains only orange/yellow surface layers, diagnostic of the Holocene relatively dry climate. The absence of the dark basal layers in the varnish further indicates a YD high stand at ~365 m bmsl and a lake level rise of at least 100 m from its Bølling‐Ållerød lowstand. This rise stands in contrast to the abrupt drop of the lake level during the Heinrich (H1) cold event, illustrating the opposite response of the EM‐CL climate to changes in the North Atlantic climate. The YD wet event most likely reflects a southward shift of the Atlantic meridional overturning circulation‐modulated midlatitude westerly wind belt in the EM‐CL region.
SIMULATION OF SOIL WATER AND SALINITY DISTRIBUTION UNDER SURFACE DRIP IRRIGATION
Authors: Selim Tarek , Berndtsson Ronny , Persson Magnus
Published: April 2013

Higher crop production and better water use efficiency are usually achieved with surface drip irrigation as compared to traditional surface irrigation methods. Increasing competition for fresh water also means a greater use of brackish water in agriculture. For this reason, the effects of soil hydraulic properties, initial soil moisture content (θi), and irrigation regime on soil water and salinity distribution under surface drip irrigation (DI) with brackish irrigation water were investigated. Model simulations were performed using the HYDRUS‐2D/3D model assuming tomato crop in saline soil. Simulation scenarios were conducted including sand, loamy sand, and sandy loam soils, together with daily and alternate‐day irrigation regimes. Two θi values were considered in the simulations. Results revealed that the effect of the irrigation regime on wetting patterns differed according to the soil's hydraulic properties, while the effect of the initial soil moisture content disappeared after a few days. The irrigation regime and θi value did not display any significant effect on soil salinity distribution. Higher soil salinity occurred along the soil surface by the end of the simulation period. The higher soil salinity was more close to the emitter in sand as compared to loamy sand and sandy loam. Water balance calculations showed that as the initial soil moisture content increased, the free drainage component increased. However, the irrigation regime and initial soil moisture content did not affect the evaporation rate and root water uptake rate. Copyright © 2013 John Wiley & Sons, Ltd.
Comparative molecular characterization of aluminum hydroxy‐gels derived from chloride and sulphate salts
Authors: Leetmaa Karl , Gomez Mario A. , Becze Levente , Guo Fuqiang , Demopoulos George P.
Published: April 2013

Background

Aluminum (III) hydroxy‐gels find important applications in areas such as paint pigments, pharmaceuticals and water treatment or toxic metal sequestration. Since the method of preparation may affect their properties and performance, in this work we prepare aluminum hydroxy‐gels from either chloride or sulphate salts and subject them to comparative characterization.

Results

Aluminum (III) hydroxy‐gels were produced by partial quick neutralization of 2 mol L−1 AlCl3 or Al(SO4)1.5 salt solutions with 5 N NaOH at room temperature. The gels were found, following ageing and water washing, to consist of 60–70 wt% Al(OH)3, 5–18 wt% Cl or SO4 and ∼20 wt% water. Both gel materials upon drying were seen to be highly porous formed from aggregates of very fine particles nucleated during the fast neutralization process. The Al(SO4)1.5‐derived gel was found to differ significantly from the AlCl3‐derived gel both in terms of surface area (38 m2 g−1 vs. 18 m2 g−1) and chemical features. The aluminum chloride gel material is probably composed of chains of aluminum octahedra (Aln(OH)2.5Cl0.5n(H2O)3n) while the aluminum sulphate gel of SO4‐stabilized Keggin Al13 structure: AlO4Al12(OH)24(SO4)3.5(H2O)12.

Conclusion

The distinct molecular structure of the aluminum sulphate‐derived gel may provide an effective matrix for hazardous metal containment. © 2013 Society of Chemical Industry
The importance of current distribution and cell hydrodynamic analysis for the design of electrocoagulation reactors
Authors: Vázquez Armando , Nava José Luis , Cruz Roel , Lázaro Isabel , Rodríguez Israel
Published: April 2013

BACKGROUND

The effects of current distribution and cell hydrodynamics on the performance of an electrocoagulation (EC) reactor were studied. This analysis only considered the distributions of primary potential and current density. The hydrodynamic behavior was analyzed by means of computational fluid dynamics (CFD) using a turbulent model (k–ϵ). For this study, only the fluid movement between electrodes was taken into account.

RESULTS

The analysis of current distribution showed the effects of cell geometry and electrode configuration on both the potential and current distributions on the anodes. Insulators placed at the edges of the electrodes produced border effects on the potential values that favored a secondary reaction and diminished the formation of aluminum clots. The CFD analysis indicated that the cell geometry arrangement generates low velocity profiles between the electrodes. From the experimental evaluation, it was observed that EC performance was improved when uniform potential and current densities were achieved with low flow velocity profiles.

CONCLUSIONS

Analysis of the hydrodynamic behavior showed the impact of different hydrodynamic phenomena on both the formation of clots and the removal of the sludge formed. Likewise, it was confirmed that in optimizing energy consumption, an analysis of current distribution is a very useful tool for evaluating the arrangement of electrodes and the cell geometry.
Linking snowflake microstructure to multi‐frequency radar observations
Authors: Leinonen J. , Moisseev D. , Nousiainen T.
Published: April 2013

Spherical or spheroidal particle shape models are commonly used to calculate numerically the radar backscattering properties of aggregate snowflakes. A more complicated and computationally intensive approach is to use detailed models of snowflake structure together with numerical scattering models that can operate on arbitrary particle shapes. Recent studies have shown that there can be significant differences between the results of these approaches. In this paper, an analytical model, based on the Rayleigh‐Gans scattering theory, is formulated to explain this discrepancy in terms of the effect of discrete ice crystals that constitute the snowflake. The ice crystals cause small‐scale inhomogeneities whose effects can be understood through the density autocorrelation function of the particle mass, which the Rayleigh‐Gans theory connects to the function that gives the radar reflectivity as a function of frequency. The derived model is a weighted sum of two Gaussian functions. A term that corresponds to the average shape of the particle, similar to that given by the spheroidal shape model, dominates at low frequencies. At high frequencies, that term vanishes and is gradually replaced by the effect of the ice crystal monomers. The autocorrelation‐based description of snowflake microstructure appears to be sufficient for multi‐frequency radar studies. The link between multi‐frequency radar observations and the particle microstructure can thus be used to infer particle properties from the observations.
Constraining U.S. ammonia emissions using TES remote sensing observations and the GEOS‐Chem adjoint model
Authors: Zhu L. , Henze D. K. , Cady‐Pereira K. E. , Shephard M. W. , Luo M. , Pinder R. W. , Bash J. O. , Jeong G.‐R.
Published: April 2013

Ammonia (NH3) has significant impacts on biodiversity, eutrophication, and acidification. Widespread uncertainty in the magnitude and seasonality of NH3 emissions hinders efforts to address these issues. In this work, we constrain U.S. NH3 sources using observations from the TES satellite instrument with the GEOS‐Chem model and its adjoint. The inversion framework is first validated using simulated observations. We then assimilate TES observations for April, July, and October of 2006 through 2009. The adjoint‐based inversion allows emissions to be adjusted heterogeneously; they are found to increase in California throughout the year, increase in different regions of the West depending upon season, and exhibit smaller increases and occasional decreases in the Eastern U.S. Evaluations of the inversion using independent surface measurements show reduced model underestimates of surface NH3 and wet deposited NHx in April and October; however, the constrained simulation in July leads to overestimates of these quantities, while TES observations are still under predicted. Modeled sulfate and nitrate aerosols concentrations do not change significantly, and persistent nitrate overestimation is noted, consistent with previous studies. Overall, while satellite‐based constraints on NH3 emissions improve model simulations in several aspects, additional assessment at higher horizontal resolution of spatial sampling bias, nitric acid formation, and diurnal variability and bi‐directionality of NH3 sources may be necessary to enhance year‐round model performance across the full range of gas and aerosol evaluations.
A comparison of parameterizations of incoming longwave radiation over melting glaciers: Model robustness and seasonal variability
Authors: Juszak I. , Pellicciotti F.
Published: April 2013

Parameterizations of incoming longwave radiation are increasingly receiving attention for both low and high elevation glacierized sites. In this paper, we test 13 clear‐sky parameterizations combined with seven cloud corrections for all‐sky atmospheric emissivity at one location on Haut Glacier d'Arolla. We also analyze the four seasons separately and conduct a cross‐validation to test the parameters’ robustness. The best parameterization is the one by Dilley and O'Brien, B for clear‐sky conditions combined with Unsworth and Monteith cloud correction. This model is also the most robust when tested in cross‐validation. When validated at different sites in the southern Alps of Switzerland and north‐western Italian Alps, all parameterizations show a substantial decrease in performance, except for one site, thus suggesting that it is important to recalibrate parameterizations of incoming longwave radiation for different locations. We argue that this is due to differences in the structure of the atmosphere at the sites. We also quantify the effect that the incoming longwave radiation parameterizations have on energy‐balance melt modeling, and show that recalibration of model parameters is needed. Using parameters from other sites leads to a significant underestimation of melt and to an error that is larger than that associated with using different parameterizations. Once recalibrated, however, the parameters of most models seem to be stable over seasons and years at the location on Haut Glacier d'Arolla.
Physical processes controlling ice concentrations in synoptically forced, midlatitude cirrus
Authors: Jensen E. J. , Lawson R. P. , Bergman J. W. , Pfister L. , Bui T. P. , Schmitt C. G.
Published: April 2013

Numerical simulations and airborne measurements are used to evaluate the impact of physical processes on synoptically forced, midlatitude cirrus ice concentrations. The agreement within a factor of 2 between ice concentrations measured with independent techniques (replicators and optical imaging probes) provides confidence in the accuracy of the in situ measurements. We use a computationally efficient modeling approach that incorporates the key cirrus physical processes, such that thousands of cloud cases can be simulated and the model results can be statistically compared with observations. One‐dimensional simulations with detailed treatments of cloud microphysical processes are driven by temperatures and vertical winds extracted from meteorological analyses. Small‐scale temperature and vertical wind perturbations associated with mesoscale waves are superimposed on the analysis fields. We find that in simulations with only homogeneous freezing nucleation, ice concentration statistics are very sensitive to the specified mesoscale wave vertical wind perturbations. With the frequency distribution of vertical winds adjusted to agree with aircraft observations, we obtain good agreement between the simulated and observed ice concentration frequency distributions. Both the observations and simulations indicate that relatively high ice concentrations (≥1000 L−1) occur rarely in these clouds (less than 1% of the time). Simulations including both homogeneous and heterogeneous nucleation indicate that even with moderate concentrations of ice nuclei (20 L−1), heterogeneous nucleation is an important ice production process, particularly for relatively low ice concentrations and warm temperatures. With enhanced ice nuclei concentrations (100 L−1), heterogeneous nucleation dominates ice production in the model. We find that it is critically important to include the impact of sedimentation on the evolution of ice concentrations when comparing model results with observations. Ice crystal collection efficiencies are poorly constrained at low temperatures, and we find that aggregation can significantly reduce ice concentrations. Sensitivity tests indicate that neither the agreement between observed and simulated ice crystal statistics nor the sensitivities indicated by the simulations are significantly affected by model assumptions such as the time periods simulated, geographic domain covered, trajectory paths calculated, or ice crystal habit assumed.
The importance of time‐varying forcing for QBO modulation of the atmospheric 11 year solar cycle signal
Authors: Matthes Katja , Kodera Kunihiko , Garcia Rolando R. , Kuroda Yuhji , Marsh Daniel R. , Labitzke Karin
Published: April 2013

We present results from three multidecadal sensitivity experiments with time‐varying solar cycle and quasi‐biennial oscillation (QBO) forcings using National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM3.1). The model experiments are unique compared to earlier studies as they use time‐varying forcings for the solar cycle only and the QBO, both individually and combined. The results show that the annual mean solar response in the tropical upper stratosphere is independent of the presence of the QBO. The response in the middle to lower stratosphere differs depending on the presence of the QBO and the solar cycle but is statistically indistinguishable in the three experiments. The seasonal evolution of the solar and the combined solar‐QBO signals reveals a reasonable agreement with observations only for the experiment in which both the solar cycle and the QBO forcing are present, suggesting that both forcings are important to generate the observed response. More stratospheric warmings occur during solar maximum and QBO west conditions. This appears to be the result of a QBO modulation of the background zonal mean wind climatology, which modifies the solar signal. Depending on the background wind, the small initial early winter solar signal in the subtropical upper stratosphere/lower mesosphere is enhanced during QBO east and diminished during QBO west conditions. This consequently influences the transfer of the solar‐QBO signal during winter and results in the observed differences during late winter.
Synthesis, Crystal Structure, and Ultraviolet–Visible Spectrum of 8–Substituted–10,10–Dimethyl–10H–pyrido[1,2–a]indolium Perchlorates–Containing Thienyl Moiety
Authors: Cao Peng , Zhang Shu Qin , Jiang Lin
Published: April 2013

Two novel compounds, 8–[2–(2–thienyl)vinyl]–10,10–dimethyl–10H–pyrido[1,2–a] indolium perchlorate (3a) and 8–[2–(5–phenyl–2–thienyl)vinyl]–10,10–dimethyl–10H–pyrido[1,2–a]indolium perchlorate (3b) were synthesized and characterized by IR, 1H–NMR, elemental analyses, and X–ray diffraction. Crystal structural analysis suggested that either 3a or 3b exhibited good coplanarity and rings and vinyl in the target molecule could make up a large conjugated system. Ultraviolet–visible absorption analysis indicated both 3a and 3b possessed large maximum absorptions, and 3b underwent a significant redshift (43.0 nm) in comparison with 3a.
Applicability of Lactobacillus plantarum IMDO 788 as a starter culture to control vegetable fermentations
Authors: Wouters Dorrit , Grosu‐Tudor Silvia , Zamfir Medana , De Vuyst Luc
Published: April 2013

BACKGROUND

Fermentation of vegetables and fruits is a traditional preservation technique, e.g. in Eastern Europe. Although usually spontaneous fermentation processes are applied, the addition of lactic acid bacteria (LAB) starter cultures could accelerate processing and improve the consistency and quality of the end‐products.

RESULTS

The application of Lactobacillus plantarum IMDO 788 as a starter culture strain for cauliflower and mixed vegetable fermentations resulted in accelerated acidification as compared with the spontaneous fermentations. The strain dominated the background microbiota throughout the process, whereas the spontaneous fermentations were characterised by widely variable species diversity. During the spontaneous fermentations, almost all carbohydrates were converted into lactic acid, ethanol, mannitol and acetic acid, indicating the participation of both heterofermentative and homofermentative LAB species. During the starter culture‐added fermentations, residual carbohydrates were found and lactic acid and ethanol were the main end‐metabolites. Vegetable‐associated aromas, ethyl acetate and isoamyl acetate were produced during all fermentations. The high concentration of ethanol and the production of ethyl acetate and isoamyl acetate suggested the involvement of yeasts during all fermentations.

CONCLUSION

Lactobacillus plantarum IMDO 788 was an adequate starter culture strain for vegetable fermentations, prevailing over endogenous LAB communities. Further optimisation of the starter culture formulation is necessary to avoid yeast growth. © 2013 Society of Chemical Industry
Amino acids profile of Serbian unifloral honeys
Authors: Kečkeš Jelena , Trifković Jelena , Andrić Filip , Jovetić Milica , Tešić Živoslav , Milojković‐Opsenica Dušanka
Published: April 2013

BACKGROUND

The free amino acids profile of 192 samples of seven different floral types of Serbian honey (acacia, linden, sunflower, rape, basil, giant goldenrod, and buckwheat) from six different regions was analysed in order to distinguish honeys by their botanical origin.

RESULTS

The most abundant amino acids were proline, alanine, phenylalanine, threonine and arginine. Based on the established amino acids profiles, some important differences have been identified among studied honey samples relying on the basic descriptive statistics data, and confirmed by multivariate chemometric methods. Principal component analysis revealed that basil honey samples form a well‐defined cluster imposed with phenylalanine content. The model obtained by linear discriminant analysis might be used to distinguish basil honey from the rest of the samples, and has moderate predictive power to separate genuine acacia, linden, sunflower and rape honeys. New data for the amino acids profile of giant goldenrod and buckwheat honey samples are presented.

CONCLUSIONS

The floral origin of honey could be successfully evaluated by its amino acids profile coupled with chemometric analysis. © 2013 Society of Chemical Industry