Distribution by Scientific Domains

Kinds of Haloes

  • cold dark matter halo
  • dark halo
  • dark matter halo
  • dark-matter halo
  • galactic halo
  • host halo
  • matter halo
  • radio halo
  • stellar halo

  • Terms modified by Haloes

  • halo mass
  • halo star

  • Selected Abstracts

    Switching the Cubic Nonlinear Optical Properties of an Electro-, Halo-, and Photochromic Ruthenium Alkynyl Complex Across Six States,

    ANGEWANDTE CHEMIE, Issue 42 2009

    Drei Schalter in einem Molekül: Die Titelverbindung (siehe Schema) enthält addressierbare Module, die unabhängig voneinander auf Protonierung (Alkinylligand,Vinylidenligand), elektrochemische (Metallredoxzentrum: RuII,RuIII) und photochemische Reize (Dithienylperfluorcyclopenten: Ringöffnung,Ringschluss) ansprechen. Die sechs Zustände wandeln sich über sieben Pfade ineinander um, wobei sich jeweils die nichtlinearen optischen Eigenschaften in bestimmter Weise ändern. [source]

    ChemInform Abstract: Syntheses and Reactions of Halo- and Arylazo-Substituted 3-(3-(2-Naphthyl)acryloyl)tropolones: Formation of ((Naphthalen-2-yl)vinyl)-substituted Heterocycle-Fused Troponoid Compounds.

    CHEMINFORM, Issue 15 2010
    Wentao Gao
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: ,-Halo-,,,-unsaturated ,-Sultones.

    CHEMINFORM, Issue 2 2008
    Samuel Braverman
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Highly Selective Reaction of ,-Halo-,,,-unsaturated Esters with Ketones or Aldehydes Promoted by SmI2: An Efficient Alternative Access to Baylis,Hillman Adducts.

    CHEMINFORM, Issue 43 2005
    Jose M. Concellon
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    A Simple and Practical Approach to ,-Halo- and ,-Phenylthio-,,,-enones.

    CHEMINFORM, Issue 28 2005
    Nagaraju Gudimalla
    No abstract is available for this article. [source]

    New Shelf-Stable Halo- and Alkoxy-Substituted Pyridylboronic Acids and Their Suzuki Cross-Coupling Reactions to Yield Heteroarylpyridines.

    CHEMINFORM, Issue 41 2003
    Paul R. Parry
    No abstract is available for this article. [source]

    Halo- and Prototropic Transformations in Bromonitrothiolene 1,1-Dioxides.

    CHEMINFORM, Issue 17 2003
    I. E. Efremova
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Synthesis and Reactions of Halo-, Arylazo-substituted 3-(3-(1-naphthyl)acryloyl)tropolones.

    Formation of (Naphthalen-1-yl)vinyl)substituted Heterocycle-fused Troponoid Compounds
    Abstract The starting substrate 3-(3-(1-naphthyl)acryloyl)tropolone (3) was achieved by the aldol condensation reaction of 3-acetyltropolone with 1-naphthaldehyde. Compound 3 reacted with bromine to afford 7-bromo-3- (3-(1-naphthyl)acryloyl)tropolone (4), 5,7-dibromo-3-(3-(1-naphthyl)acryloyl)tropolone (5) according to the molar ratio of the reactants. Iodination of 3 gave 7-iodo-3-(3-(1-naphthyl)acryloyl)tropolone (6). Azo-coupling reactions of 3 gave the 5-arylazo-3-(3-(1-naphthyl)acryloyl)tropolones (7,8). Compounds 3, 4, 6 reacted respectively with hydroxyamine to give the corresponding 3-[2-(1-naphthyl)vinyl]-8H -cyclohepta[d]isoxazol-8-ones (9,11). The reactions of 3, 5 with phenylhydrazine and substituted phenylhydrazines gave 3-[2-(1-naphthyl)vinyl]-1-phenylcyclohepta[c]pyrazol-8(1H)-ones (12,18). [source]

    Halo stochasticity in global clustering analysis

    S. Bonoli
    ABSTRACT Galaxy clustering and cosmic magnification can be used to estimate the dark matter power spectrum if the theoretical relation between the distribution of galaxies and the distribution of dark matter is precisely known. In the present work, we study the statistics of haloes, which in the halo model determines the distribution of galaxies. Haloes are known to be biased tracer of dark matter, and at large scales it is usually assumed there is no intrinsic stochasticity between the two field (i.e. r= 1). Following the work of Seljak & Warren, we explore how correct this assumption is and, moving a step further, we try to qualify the nature of stochasticity. We use principal component analysis applied to the outputs of a cosmological N -body simulation as a function of mass to: (i) explore the behaviour of stochasticity in the correlation between haloes of different masses; and (ii) explore the behaviour of stochasticity in the correlation between haloes and dark matter. We show results obtained using a catalogue with 2.1 million haloes, from a pmfast simulation with box size of 1000 h,1 Mpc and with about four billion particles. In the relation between different populations of haloes, we find that stochasticity is not negligible even at large scales. In agreement with the conclusions of Tegmark & Bromley, who studied the correlations of different galaxy populations, we found that the shot noise subtracted stochasticity is qualitatively different from ,enhanced' shot noise and, specifically, it is dominated by a single stochastic eigenvalue. We call this the ,minimally stochastic' scenario, as opposed to shot noise-like stochasticity which is ,maximally stochastic'. In the correlation between haloes and dark matter, we find that the stochasticity is minimized, as expected, near the dark matter peak (k, 0.02 h Mpc,1 for a , cold dark matter cosmology), and, even at large scales, it is of the order of 15 per cent above the shot noise. Moreover, we find that the reconstruction of the dark matter distribution is improved when we use the principal component eigenvectors as tracers of the bias, but still the reconstruction is not perfect, due to stochasticity. [source]

    Haloes around edge-on disc galaxies in the Sloan Digital Sky Survey

    Stefano Zibetti
    ABSTRACT We present a statistical analysis of halo emission for a sample of 1047 edge-on disc galaxies imaged in five bands by the Sloan Digital Sky Survey (SDSS). Stacking the homogeneously rescaled images of the galaxies, we can measure surface brightnesses as deep as ,r, 31 mag arcsec,2. The results strongly support the almost ubiquitous presence of stellar haloes around disc galaxies, whose spatial distribution is well described by a power law ,,r,3, in a moderately flattened spheroid (c/a, 0.6). The colour estimates in g,r and r,i, although uncertain, give a clear indication for extremely red stellar populations, hinting at old ages and/or non-negligible metal enrichment. These results support the idea of haloes being assembled via early merging of satellite galaxies. [source]

    Constructing Identities in Early Iron Age Thessaly: The Case of the Halos Tumuli

    Ioannis Georganas
    This paper examines the Early Iron Age tumulus,cemetery of Halos in south,eastern Thessaly, with its unique cremation pyre,cairn combination. As there are no parallels for such combination of burial practices either in Thessaly or in any other area of the Greek world, it has usually been suggested that the tumuli were erected by people foreign to Thessaly, most probably of a northern origin. This paper presents evidence suggesting a local custom closely related to the desire to create a new identity. [source]

    Halodecarboxylation Reaction of 4-Alkylidene-,-lactams

    Paola Galletti
    Abstract The synthesis of halo- and dihalovinyl-,-lactams by a halodecarboxylation reaction has been developed. Optimized procedures gave good yields of dibromo-, iodo- and diiodovinyl derivatives. The unprecedented synthesis of dihalo compounds by a Hunsdieker reaction was investigated in detail by 1H NMR analysis, which allowed the formulation of a reaction mechanism and revealed the role of triethylamine as a deiodinating agent. The dibromo- and diiodoalkylidene-,-lactams obtained were tested in a cross-coupling reaction with dimethylzinc. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    The immunosuppressive drug leflunomide affects mating-pheromone response and sporulation by different mechanisms in Saccharomyces cerevisiae

    Hiro-aki Fujimura
    Abstract Leflunomide (LFM) is a novel anti-inflammatory and immunosuppressive drug, and inhibits the growth of cytokine-stimulated lymphoid cells in vitro. The effect of LFM on haploid and diploid cells of Saccharomyces cerevisiae was investigated to elucidate the molecular mechanism of action of the drug. Using a halo assay, LFM was shown to enhance the cell cycle arrest of haploid cells induced by mating pheromone ,-factor. LFM also inhibited sporulation of diploid cells completely. S. cerevisiae genes which were cloned to suppress the anti-proliferative effect when present in increased copy number were introduced and examined for their activity to suppress the effect of LFM. Out of them, MLF4/SSH4, was found to suppress the sporulation-inhibitory effect of LFM. However, MLF4 failed to suppress the enhancing effect of LFM on pheromone response. Thus, LFM is suggested to act on haploid and diploid cells by different mechanisms. [source]

    The mechanism of neutral amino acid decomposition in the gas phase.

    N -dimethylglycine, N -dimethylglycine ethyl ester, The elimination kinetics of N, ethyl 1-piperidineacetate
    The gas-phase elimination kinetics of the ethyl ester of two ,-amino acid type of molecules have been determined over the temperature range of 360,430°C and pressure range of 26,86 Torr. The reactions, in a static reaction system, are homogeneous and unimolecular and obey a first-order rate law. The rate coefficients are given by the following equations. For N,N-dimethylglycine ethyl ester: log k1(s,1) = (13.01 ± 3.70) , (202.3 ± 0.3)kJ mol,1 (2.303 RT),1 For ethyl 1-piperidineacetate: log k1(s,1) = (12.91 ± 0.31) , (204.4 ± 0.1)kJ mol,1 (2.303 RT),1 The decompositon of these esters leads to the formation of the corresponding ,-amino acid type of compound and ethylene. However, the amino acid intermediate, under the condition of the experiments, undergoes an extremely rapid decarboxylation process. Attempts to pyrolyze pure N,N-dimethylglycine, which is the intermediate of dimethylglycine ethyl ester pyrolysis, was possible at only two temperatures, 300 and 310°C. The products are trimethylamine and CO2. Assuming log A = 13.0 for a five-centered cyclic transition-state type of mechanism in gas-phase reactions, it gives the following expression: log k1(s,1) = (13.0) , (176.6)kJ mol,1 (2.303 RT),1. The mechanism of these ,-amino acids differs from the decarbonylation elimination of 2-substituted halo, hydroxy, alkoxy, phenoxy, and acetoxy carboxylic acids in the gas phase. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33:465,471, 2001 [source]

    Hereditary palmoplantar keratoderma (four cases in three generations)

    Virendra N. Sehgal MD
    A 39-year-old man reported with progressive thickening of the skin of the hands and feet and an inability to flex his hand. It was largely asymptomatic; however, brisk walking caused excessive sweating, pain, and widening of the fissures on the soles of the feet. He was unable to walk barefooted. According to his mother, the first episode presented with blistering at 7 days of age. Ever since, the condition has steadily worsened to acquire the current status. He was married at the age of 18 years, and had a stillborn child 18 months afterwards. Presently, he has three children, two girls aged 14 and 12 years and a son aged 10 years. Both the daughters are similarly affected. While cataloguing the details of the pattern of inheritance, the mother of the index case was also found to be affected (Fig. 1). The natural history of the disease was identical. Figure 1. Palmoplantar keratoderma: pattern of inheritance; black indicates affected individuals Examination of the palms was marked by pronounced thickening of the skin resulting in the masking of palmar creases. The thickening was well demarcated and its margins were prominent and surrounded by an erythematous halo. The color of the skin was yellow and waxy (Fig. 2a). Contractures were present on all the fingers; nevertheless, the deformity of the middle and distal interphalangeal joints of the little finger was prominent. The soles of the feet had a similar morphology. In addition, marked fissuring was obvious (Fig. 2b). His daughters had an identical affliction of the palms and soles. The texture and morphology of the nails were normal. Light microscopy performed on scrapings from the fissures, mounted on 10% potassium hydroxide, revealed mycelia (hyphae) and spores. Figure 2. Well-demarcated hyperkeratosis depicting the yellow, waxy color of the palms, with masking of creases (a). Marked fissuring on the soles was prominent (b) Hematoxylin and eosin-stained microsections from the palms and soles showed exquisite changes in the epidermis characterized by considerable uniform orthohyperkeratosis. Hypergranulosis and acanthosis were other associated changes. In addition, perinuclear vacuolization and keratohyalin granules of varying sizes and shapes were located at the periphery of the cells. A sparse mononuclear infiltrate was located at the dermo-epidermal junction. Hyphae and spores of fungi were also identified in the stratum corneum (Fig. 3). Figure 3. Orthohyperkeratosis, hypergranulosis, and acanthosis. Perinuclear vacuolization and keratohyalin granules at the periphery of the cells; a sparse mononuclear infiltrate was also present (hematoxylin and eosin, ×,40 (a), ×,400 (b)) Itraconazole, 400 mg/day in two equally divided doses, was administered with major meals for 7 days. In addition, high doses of vitamin A (100,000 IU) were given daily for 2 weeks, supplemented by 12% salicylic acid (Salicylix SF12) ointment for daytime application and an ointment containing 6% coal tar and 3% salicylic acid (Salytar) for night-time application. This treatment is useful in recalcitrant cases. [source]

    Assessment Center Procedures: Cognitive Load During the Observation Phase

    Nanja J. Kolk
    This study explores the traditional procedure of observing assessment center exercises while taking notes vs. an alternative procedure where assessors merely observe and postpone note-taking until immediately after the exercise. The first procedure is considered to be cognitively demanding due to the requirement of simultaneous note-taking and observing. Also, dual task processing (concurrent observing and note-taking) is considered to be especially demanding for assessors without rating experience. The procedures are evaluated using a 2 × 2 design (with note-taking/without note-taking × experienced/inexperienced). Some 121 experienced and inexperienced assessors rated videotaped candidates, observing either with or without taking notes. Results showed that experienced assessors yield significantly higher differential accuracy than inexperienced assessors. We did not find an effect of observation procedure on accuracy, interrater reliability or halo. Implications for future research are described. [source]

    Stable and Catalytically Highly Active ansa Compounds with Cycloalkyl Moieties as Bridging Units

    Alejandro Capapé
    Abstract The complexes Mo{,5 -C5H4[CH(CH2)3]-,1 -CH}(CO)3 (2a) and W{,5 -C5H4[CH(CH2)3]-,1 -CH}CO)3 (2b) were synthesized by reacting spiro[4.2]bicyclo[4.1]deca-6,8-diene (1) with the tri(acetonitrile)tri(carbonyl)metal complexes M(CO)3(CH3CN)3 (M=Mo, W). Thermogravimetric (TGA) measurements confirm that the complexes are stable up to 140,°C in air in the solid state. The complexes 2a and 2b are very active catalysts at room temperature for the epoxidation of cyclooctene with tert -butyl hydroperoxide (TBHP) as oxidant, reaching TOFs of up to 3650,h,1. Complex 2a achieves a quantitative product yield without formation of any by-products within 1.5,h, outperforming previously published ansa compounds and performing on par with the cyclopentadienyltri(carbonyl)(halo)- or (alkyl)molybdenum compelxes CpMo(CO)3R (R=Hal, Me, Et). [source]

    Cytochemical and ultrastructural characterization of growing colonies of human embryonic stem cells

    JOURNAL OF ANATOMY, Issue 4 2004
    Kohei Johkura
    Abstract The morphology of human embryonic stem (ES) cells changes with their colonial growth. For a better understanding of the growth of ES cell colonies in culture, we determined their cytochemical and ultrastructural characteristics focusing on images of living cells under a phase contrast microscope. During the initial growth stages, the colonies exhibited a mosaic appearance with discernible cell,cell borders. PAS staining coupled with amylase digestion demonstrated that the bright granules and dark deposits in the cytoplasm contained glycogen. Ultrastructurally they were glycogen accumulations, and clustered open spaces associated with various amounts of glycogen. Although intercellularly heterogeneous, these structures were detectable throughout colony growth. As the colonies grew, compaction towards the centre emerged and increased, accompanied by heterogeneous increases in coarse particles with or without a halo. TUNEL showed these particles to consist at least in part of apoptotic cells/bodies. Transmission electron microscopy indicated that most apoptotic cells had been phagocytosed by intact ES cells. Spontaneous differentiation was detected occasionally in the periphery of the colonies. The presence of PAS-positive fibrous structures not susceptible to amylase digestion and laminin-immunoreactivity indicated the accumulation of extracellular matrix in the peripheral differentiated areas. These findings made it possible to determine the growth stage of human ES cell colonies. [source]

    Chitinolytic activities in Bacillus thuringiensis and their synergistic effects on larvicidal activity

    M. Liu
    Aims: To investigate the distribution of chitinase in Bacillus thuringiensis strains, and the enhancing effects of the chitinase-producing B. thuringiensis strains on insecticidal toxicity of active B. thuringiensis strain against Spodoptera exigua larvae. Methods and Results: The chitinolytic activities of B.thuringiensis strains representing the 70 serotypes were investigated by the whitish opaque halo and the colorimetric method. Thirty-eight strains produced different levels of chitinase at pH 7·0, and so did 17 strains at pH 10·0. The strain T04A001 exhibited the highest production, reaching a specific activity of 355 U ml,1 in liquid medium. SDS-PAGE and Western blotting showed that the chitinase produced by some B. thuringiensis strains had a molecular weight of about 61 kDa. The bioassay results indicated that the chitinase-producing B. thuringiensis strains could enhance the insecticidal activity of B. thuringiensis strain DL5789 against S. exigua larvae, with an enhancing ratio of 2·35-fold. Conclusion: This study demonstrated that chitinase was widely produced in B. thuringiensis strains and some of the strains could enhance the toxicity of active B. thuringiensis strain. Significance and Impact of the Study: This is the first investigation devoted exclusively to analyse the distribution of chitinase in B. thuringiensis. It infers that the chitinase produced by B. thuringiensis might play a role in the activity of the biopesticide. [source]

    Examination and Measurement of Halo Via Curvilinear Regression: A New Approach to Halo1

    Adrian Thomas
    Much disagreement and confusion has surrounded the nature of the relationship between halo and performance rating accuracy. Traditionally, the relationship has been assumed to be linear (Cooper, 1981), but Fisicaro (1988) proposed that the relationship between halo and performance rating accuracy is, instead, curvilinear. Using the halo index suggested by Balzer & Sulsky (1992), the results of the present study provided empirical evidence to support Fisicaro's proposal. Future research examining the relationship between halo and accuracy should consider the use of quadratic models, instead of linear ones. For the practitioner, this result implies that low rating dimension intercorrelations (negative halo) may lead to inaccuracy in ratings in much the same way as do high rating dimension intercorrelations (positive halo). [source]

    Spatial Distribution of Bax and Bcl-2 in Osteocytes After Bone Fatigue: Complementary Roles in Bone Remodeling Regulation?,

    Olivier Verborgt
    Abstract Osteocyte apoptosis appears to play a key role in the mechanism by which osteoclastic resorption activity targets bone for removal, because osteocyte apoptosis occurs in highly specific association with microdamage and subsequent remodeling after fatigue. However, beyond terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling (TUNEL) assay, little is known about the mechanisms controlling osteocyte apoptosis in vivo. In the current studies, expression of Bax, a proapoptotic gene product, and Bcl-2, an antiapoptotic gene product, was determined in osteocytes of fatigued rat bone using immunocytochemical staining and compared with TUNEL staining patterns. Bax and Bcl-2 were evident in osteocytes by 6 h after loading. Moreover, Bax and Bcl-2 in osteocytes were expressed differently as a function of distance from microdamage sites. The peak of Bax expression and TUNEL+ staining in osteocytes was observed immediately at the microcrack locus, which is where bone resorption occurs in this system; in contrast, Bcl-2 expression, the antiapoptotic signal, reached its greatest level at some distance (1-2 mm) from microcracks. These data suggest that near sites of microinjury in bone, those osteocytes that do not undergo apoptosis are prevented from doing so by active protection mechanisms. Moreover, the zone of apoptotic osteocytes around microcracks was effectively "walled in" by a surrounding halo of surviving osteocytes actively expressing Bcl-2. Thus, the expression pattern of apoptosis-inhibiting gene products by osteocytes surrounding the apoptotic osteocyte at microdamage sites also may provide important signals in the guidance of resorption processes that occur in association with osteocyte apoptosis after fatigue. [source]

    Thyroid follicular neoplasms: Can sonography distinguish between adenomas and carcinomas?

    Hyung Suk Seo MD
    Abstract Purpose The purpose of this study was to determine whether sonography (US) can usefully differentiate thyroid follicular adenoma (FA) and follicular carcinoma (FC). Methods This retrospective study included 60 pathologically proven FAs and 66 FCs in 123 consecutive patients (17 males and 106 females) with a mean age of 47 ± 13 years, (17,73 years) who underwent thyroid surgery. We analyzed US features of each nodule, including maximum diameter, echogenicity, composition, presence of calcification, margins, and presence of halo. The frequencies of each US feature were compared by using the ,2 test or Fisher's exact test between FAs and FCs. The relative risk of malignancy was evaluated by logistic regression analysis. Results Isohypoechoic echogenicity, predominantly solid or mixed echotexture, and presence of microcalcifications or rim calcifications were associated with FC (p < 0.05). Logistic regression analysis demonstrated that predominantly solid or mixed echotexture and microcalcifications or rim calcifications were associated with significant increases in relative risk for FC (odds ratio 8.1 and odds ratio 13.5, respectively, p < 0.01). Conclusions The US features of isohypoechoic echogenicity, predominantly solid or mixed echotexture, and microcalcifications or rim calcifications are more common in FC than in FA. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2009 [source]

    Sonographic findings of mesenteric panniculitis: Correlation with CT and literature review

    Nuria Rosón MD
    Abstract Purpose. To evaluate the sonographic findings of mesenteric panniculitis (MP) and correlate them with CT findings. Methods. We retrospectively evaluated the clinical, CT, and sonographic findings in 26 cases of MP in our hospital between January 1997 and July 2003. We also reviewed the sonographic features of MP previously described in the literature. Results. The sonographic findings were well correlated to CT in 24 of 26 patients (92%). In these 24 cases, abdominal sonographic examination revealed a hyperechogenic, well-defined fatty mass (corresponding to the pseudocapsule CT sign) in the root of the mesentery, displacing the bowel loops. We found a clear interface between MP and normal intra abdominal fat. Examination with color Doppler sonography revealed the nondeviated mesenteric vessels within the mass. The persence of MP improved sonographic transmission in 9 obese patients and enabled the retroperitoneal vessels to be clearly visualized. Sonography was unable to demonstrate the preservation of the fat nearest the mesenteric vessels corresponding to the "fatty halo" sign on CT. Conclusions. Sonography is useful in the diagnostic workup for MP. The characteristic sonographic features of MP (well-defined mass, homogeneous hyperechogenicity of the mass, nondeviated vessels within the mass, and displaced bowel loops) correlate well with CT findings. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:169,176, 2006 [source]

    A novel route to the 5,6-dihydro-4-H-thieno[3,2-b]pyrrol-5-one ring system involving an intermediate substituted-thiophene synthesis

    Shuanghua Hu
    A novel route to electron-deficient thienopyrrolones is disclosed. The target heterocycles are concisely constructed by condensation of activated ,- or ,-halo-substituted acrylonitriles, or ortho -substituted halo, cyano heterocycles with mercaptopyruvate, followed by reduction and subsequent lactamization. [source]

    Kinetics and mechanism of sodium N -halo- p -toluenesulfonamides oxidation of diclofenac in alkaline medium

    AICHE JOURNAL, Issue 12 2009
    Abstract Diclofenac belongs to a class of drugs called nonsteroidal antiinflammatory drugs. The kinetics and mechanism of oxidation of diclofenac by sodium N -halo- p -toluenesulfonamides viz., chloramine-T and bromamine-T in NaOH medium have been studied at 293 K. Under comparable experimental conditions, reactions with both the oxidants follow identical kinetics with a first-order dependence on each [oxidant]o and a fractional-order dependence on each [diclofenac]o and [NaOH]. Activation parameters have been computed. N -hydroxyldiclofenac is identified as the oxidation product of diclofenac. Michaelis-Menten type of mechanism has been suggested. The rate of oxidation of diclofenac is about four-fold faster with bromamine-T when compared with chloramine-T. This may be attributed to the difference in electrophilicities of Cl+ and Br+ ions and also the van der Waal's radii of chlorine and bromine. Plausible mechanism and related rate law have been designed for the observed kinetics. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    Reactions of halo- and dihaloadamantanes with nitromethane anions by the SRN1 mechanism

    Ana N. Santiago
    Abstract The reactions of 1-bromo-, 2-bromo-, 1,3-dibromo- and 1,4-dibromoadamantane with ,CH2NO2 anions were studied in DMSO and in liquid ammonia. The photostimulated reaction of 1-haloadamantane (1-AdX, X,=,Br, I) or 2-AdBr with ,CH2NO2 anions gave good yields of the substitution product 1-AdCH2NO2 and 2-AdCH2NO2, respectively, in the presence of the enolate anions of acetone (entrainment conditions). On the other hand, 1-adamantanol was the main product of the reaction performed in DMSO without irradiation, but not in liquid ammonia. 1,3-Dibromo and 1,4-dibromoadamantane reacted with ,CH2NO2 anions under irradiation in the presence of the enolate anions of acetone. The first compound gave the disubstitution product 11, and the second the monobromo-substitution products 15 and 16, together with the disubstitution product 17. Compounds 15 and 16 were shown to be intermediates in the formation of 17. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Phase Behavior, 3-D Structure, and Rheology of Colloidal Microsphere,Nanoparticle Suspensions

    Summer K. Rhodes
    A new route for tailoring the behavior of colloidal suspensions through nanoparticle additions is reviewed. Specifically, the interparticle interactions, phase behavior, 3-D structure, and rheological properties of microsphere,nanoparticle mixtures that possess both high charge and size asymmetry are described. Negligibly charged microspheres, which flocculate when suspended alone, undergo a remarkable stabilizing transition upon the addition of highly charged nanoparticles. The formation of a dynamic nanoparticle halo around each colloid induces an effective repulsion between the microspheres that promotes their stability. With increasing nanoparticle concentration, the colloids again undergo flocculation because of the emergence of an effective microsphere attraction, whose magnitude exhibits a quadratic dependence on nanoparticle volume fraction. The broader impact of these observations on colloidal stabilization and assembly of advanced ceramics is highlighted. [source]

    Selective medium based on tyrosine metabolism for the isolation and enumeration of Brevibacillus brevis (Bacillus brevis)

    S.G. Edwards
    Aims: To develop a selective medium for the enumeration of Brevibacillus brevis Nagano spores from soil and plant material. Methods and Results: Tyrosine agar was developed as a selective medium and compared with nutrient agar for the enumeration of B. brevis Nagano spores from sterile and non-sterile plant and soil extracts. Brevibacillus brevis Nagano colonies could be easily identified only on tyrosine agar due to their clear halo and distinct colony morphology. Identification was confirmed by thin layer chromatography of the antibiotic, gramicidin S, produced by this strain. Conclusions: Tyrosine agar was shown to be a suitable selective medium for the enumeration of B. brevis Nagano. Significance and impact of the study: The medium developed, tyrosine agar, can be used to monitor the population of the biological control agent, B. brevis Nagano, and will allow detailed studies within the crop environment. [source]

    Petrology of the Yamato nakhlites

    N. Imae
    They are paired cumulate clinopyroxenites. We obtained the intercumulus melt composition of the Yamato nakhlites and here call it the Yamato intercumulus melt (YIM). The YIM crystallized to form the augite rims, the olivine rims and the mesostasis phases in the cumulates. The augite rims consist of two layers: inner and outer. The crystallization of the inner rim drove the interstitial melt into the plagioclase liquidus field. Subsequently, the residual melt crystallized pigeonites and plagioclase to form the outer rims and the mesostasis. Three types of inclusions were identified in olivine phenocrysts: rounded vitrophyric, angular vitrophyric, and monomineralic augite inclusions. The monomineralic augite inclusions are common and may have been captured by growing olivine phenocrysts. The rounded vitrophyric inclusions are rare and may represent the composition of middle-stage melts, whereas the angular vitrophyric inclusions seem to have been derived from fractionated late-stage melts. Glass inclusions occur in close association with titanomagnetite and ferroan augite halo in phenocryst core augites and the assemblages may be magmatic inclusions in augites. We compared the YIM with compositions of magmatic inclusions in olivine and augite. The composition of magmatic inclusions in augite is similar to the YIM. Phenocrystic olivines contain exsolution lamellae, augite-magnetite aggregates, and symplectites in the cores. The symplectites often occur at the boundaries between olivine and augite grains. The aggregates, symplectite and lamellae formed by exsolution from the host olivine at magmatic temperatures. We present a formational scenario for nakhlites as follows: (1) accumulation of augite, olivine, and titanomagnetite phenocrysts took place on the floor of a magma chamber; (2) olivine exsolved augite and magnetite as augite-magnetite aggregates, symplectites and lamellae; (3) the overgrowth on olivine phenocrysts formed their rims, and the inner rims crystallized on augite phenocryst cores; and finally, (4) the outer rim formed surrounding the inner rims of augite phenocrysts, and plagioclase and minor minerals crystallized to form mesostasis under a rapid cooling condition, probably in a lava flow or a sill. [source]

    Xanthomonas citri: breaking the surface

    Asha M. Brunings
    SUMMARY Taxonomy: Bacteria; Proteobacteria, Gammaproteobacteria; Xanthomonadales; Xanthomonadaceae, Xanthomonas. Microbiological properties: Gram-negative, obligately aerobic, straight rods, motile by a single polar flagellum, yellow pigment. Related species:X. campestris , X. axonopodis , X. oryzae , X. albilineans . Host range: Affects Rutaceous plants, primarily Citrus spp., Fortunella spp., and Poncirus spp., world-wide. Quarantined pathogen in many countries. Economically important hosts are cultivated orange, grapefruit, lime, lemon, pomelo and citrus rootstock. Disease symptoms: On leaves, first appearance is as oily looking, 2,10 mm, similarly sized, circular spots, usually on the abaxial surface. On leaves, stems, thorns and fruit, circular lesions become raised and blister-like, growing into white or yellow spongy pustules. These pustules then darken and thicken into a light tan to brown corky canker, which is rough to the touch. On stems, pustules may coalesce to split the epidermis along the stem length, and occasionally girdling of young stems may occur. Older lesions on leaves and fruit tend to have more elevated margins and are at times surrounded by a yellow chlorotic halo (that may disappear) and a sunken centre. Sunken craters are especially noticeable on fruit, but the lesions do not penetrate far into the rind. Defoliation and premature abscission of affected fruit occurs on heavily infected trees. Useful websites: ; [source]