1,530 research outputs found
Cutinase activity in supercritical and organic media: water activity, solvation and acid–base effects
We performed a comparative study on the activity of Fusarium solani pisi cutinase immobilized on zeolites NaA and NaY, in n-hexane, acetonitrile, supercritical ethane (sc-ethane) and sc-CO2, at two different water activity (aW) values set by salt hydrate pairs in situ and at acid–base conditions fixed with solid-state buffers of aqueous pKa between 4.3 and 10.6. The reaction studied was the transesterification of vinyl butyrate by (R,S)-2-phenyl-1-propanol. The transesterification activity of cutinase was highest and similar in sc-ethane and in n-hexane,about one order of magnitude lower in acetonitrile and even lower in sc-CO2. Activity coefficients (γ) generated for the two substrates indicated that they were better solvated in acetonitrile and thus less available for binding at the active site than in the other three solvents.
γ data also suggested higher reaction rates in sc-ethane than in n-hexane, as observed, and provided evidence for a direct negative effect of sc-CO2 on enzyme activity. Manipulation of the acid–base conditions of the media did not afford any improvement of the initial rates of transesterification relative to the blanks (no added acid–base buffer, only salt hydrate pair), except in the case of cutinase immobilized on zeolite NaA in sc-ethane at aW = 0.7. The poor performance of the blank in this case and the great improvement observed in the presence of a basic buffer suggest a deleterious acidic effect in the medium which, an experiment without additives confirmed, was not due to the known
acidic character of the salt hydrate pair used to set aW = 0.7. In acetonitrile, increasing aW was accompanied by a decrease in initial rates of transesterification, unlike in the other solvents. There was considerable hydrolysis in acetonitrile, where initial rates of hydrolysis increased
about 20-fold from aW = 0.2 to 0.7. Hydrolysis was less pronounced in sc-ethane and in n-hexane, and only at aW = 0.7, and in sc-CO2 butyric acid was detected only at very long reaction times, in agreement with a generally low catalytic activity. Cutinase enantio-selectivity towards the alcohol substrate was low and unaffected by any manipulation of medium conditions.This work has been supported by Fundação para a Ciência e Tecnologia (FCT, Portugal) through the contracts PRAXIS/PBIO/14314/1998 and POCTI/35429/QUI/2000 and the grant PRAXIS XXI/BD/21615/99 (S. Garcia), and by FEDER.We thank Ricardo Baptista for help in the production of cutinase
The formation of planetary disks and winds: an ultraviolet view
Planetary systems are angular momentum reservoirs generated during star
formation. This accretion process produces very powerful engines able to drive
the optical jets and the molecular outflows. A fraction of the engine energy is
released into heating thus the temperature of the engine ranges from the 3000K
of the inner disk material to the 10MK in the areas where magnetic reconnection
occurs. There are important unsolved problems concerning the nature of the
engine, its evolution and the impact of the engine in the chemical evolution of
the inner disk. Of special relevance is the understanding of the shear layer
between the stellar photosphere and the disk; this layer controls a significant
fraction of the magnetic field building up and the subsequent dissipative
processes ougth to be studied in the UV.
This contribution focus on describing the connections between 1 Myr old suns
and the Sun and the requirements for new UV instrumentation to address their
evolution during this period. Two types of observations are shown to be needed:
monitoring programmes and high resolution imaging down to, at least,
milliarsecond scales.Comment: Accepted for publication in Astrophysics and Space Science 9 figure
Susceptibility testing of Candida albicans and Candida glabrata to Glycyrrhiza glabra L.
Medicinal plants and their botanical formulations have gained a pivotal attention among scientific researchers mainly due to its action as health promoters. Licorice (Glycyrrhiza glabra L.) constitutes a great example, with an increasingly evidenced antimicrobial potential. Opportunistic yeast infections constitute an alarming public health problem, highly exacerbated by the inefficacy of antifungal drugs and the increase of drug-resistant microorganisms, being Candida species one of the most common invaders. The present work aims to assess Candida glabrata and Candida albicans susceptibility to G. glabra methanol: water extract by using flow cytometry and transmission electron microscopy techniques. After 5 minutes, licorice extract (1.5 mg/mL) altered Candida membrane potential. Within an hour, it induced primary damages on Candida species cells, causing cell cytoplasm disorganization with high evidence of cell membrane invaginations, making cells turgid. Thus, based on the current findings, licorice extract seems to be a promising anti-Candida agent, without presenting any toxic potential at the effective concentrations used.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) for N. Martins grant (SFRH/BD/87658/2012) and financial support to the research centre CIMO (strategic project PEst-OE/ AGR/UI0690/2014). This work was also supported by the Programa Operacional, Fatores de competitividade – COMPETE and by national funds through FCT – Fundação para a Ciência e a Tecnologia on the scope of the projects FCT PTDC/SAU-MIC/119069/2010, RECI/EBBEBI/0179/2012 and PEst-OE/EQB/LA0023/2013. The authors thank the Project “BioHealth – Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE-07-0124-FEDER-000027, cofunded by the Programa Operacional Regional do Norte (ON.2–O Novo Norte), QREN, FEDER.info:eu-repo/semantics/publishedVersio
Pragas da soja no Brasil e seu manejo integrado.
Pragas da soja; Pragas que atacam as folhas: Anticarsia gemmatalis (Lep.: Noctuidae); Pseudoplusia includens (Lep.: Noctuidae); Coleopteros desfolhadores; Outros organismos que atacam as folhas; Pragas que atacam vagens e graos: Percevejos sugadores de sementes; Lagartas das vagens; Brocas das vagens; Pragas que atacam plantulas, hastes e peciolos: Sternechus subsignatus (Col.: Curculionidae); Elasmopalpus lignosellus (Lep.: Pyralidae); Epinotia aporema (Lep.: Tortricidae); Outros insetos que atacam plantulas, hastes e peciolos; Pragas que atacam as raizes da soja: Coros; Percevejos-castanho-da-raiz; Outros insetos que atacam as raizes; Inimigos naturais das pragas da soja; Predadores: Hemipteros; Coleopteros; Parasitoides: Parasitoides de lagartas; Parasitoides de percevejos; Entomopatogenos: Virus; Fungos; Amostragem das pragas; Controle integrado e nivel de acao; Controle integrado das pragas que atacam as folhas: Anticarsia gemmatalis; Pseudoplusia includens e outros Plusiinae;; Coleopteros desfolhadores; Outros organismos que atacam as folhas; Controle integrado das pragas que atacam as vagens e graos: Percevejos; Lagarta-das-vagens; Broca-das-vagens; Controle integrado das pragas que atacam plantulas, hastes e peciolos: Sternechus subsignatus; Epinotia aporema; Controle integrado das pragas que atacam as raizes: Coros; Percevejo-castanho-da-raiz.bitstream/item/128003/1/ID-6173.pd
Energy calibration of the NEXT-White detector with 1% resolution near Q ββ of 136Xe
Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searches. [Figure not available: see fulltext.
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Occasional Finding Of Neurological Disorders During Children Hearing Loss Evaluation Using The Abr
One of the most important applications of the Brainstem evoked response audiometry (ABR) is in the evaluation of hearing loss in children. Today the ABR is also indicated in the screening of cochleovestibular syndromes to detect retrocochlear lesions, to monitor patients in a coma (brain death), in monitoring the brainstem during skull base surgery, etc. Among the many BERA qualities, is its capacity to evaluate the neurophysiologic integrity of the auditory brainstem pathway. In doing so, sometimes while evaluating hearing function in children we are faced with ABR waves that suggest the presence of retrocochlear lesions (trace asymmetry, increased interpeak intervals), many times confirmed through image studies. These cases are seen as occasional findings of neurologic disorders during children hearing loss evaluation. In this study we report 2 cases of neurologic disorders diagnosed with the use of the ABR to evaluate hearing loss in children. © Revista Brasileira de Otorrinolaringologia. All Rights reserved.733424428Jewett, D.L., Romano, M.N., Williston, J.S., Human auditory evoked potentials: Possible brain stem components detected on the scalp (1970) Science, 167 (924), pp. 1517-1518Starr, A., Hamilton, A.E., Correlation between confirmed sites of neurological lesions and abnormalities of far-field auditory brainstem responses (1976) Electroencephalogr Clin Neurophysiol, 41 (6), pp. 595-608Levine, R.A., Gardner, J.C., Fullerton, B.C., Stufflebeam, S.M., Carlisle, E.W., Furst, M., Effects of multiple sclerosis brainstem lesions on sound lateralization and brainstem auditory evoked potentials (1993) Hear Res, 68 (1), pp. 73-88Moller, A.R., Jannetta, P.J., Auditory evoked potentials recorded intracranially from the brain stem in man (1982) Exp Neurol, 78 (1), pp. 144-157Hashimoto, I., Ishiyama, Y., Yoshimoto, T., Nemoto, S., Brain-stem auditory-evoked potentials recorded directly from human brain-stem and thalamus (1981) Brain, 104 (PART 4), pp. 841-859Anson, B., Donaldson, J., (1981) Surgical anatomy of the temporal bone, , 3rd ed. Philadelphia: W.B. Saunders;Sousa LCA, Piza MRT, Costa SS. Poster: Brainstem Evoked Auditory Potential (ABR) in Neurology and Neurosurgery: 99th Meeting of the American Academy of Otolaryngology- Head and Neck Surgery. New Orleans, USA, Setembro1995Sousa, L.C.A., Piza, M.R.T., Costa, S.S., Diagnosis of Menières Disease: Routine and Extended Tests (2002) Otolaryngol Clin North Am, , JuneMarangos, N., Maier, W., Merz, R., Laszig, R., Brainstem response in cerebellopontine angle tumors (2001) Otol Neurotol, 22 (1), pp. 95-99Haapaniemi, J., Laurikainen, E., Jahansson, R., Rinne, T., Varpula, M., Audiovestibular findings and location of na acoustic neuroma (2000) Eur Arch Otorhinolaryngol, 257 (4), pp. 237-241Costa, S.S., Sousa, L.C.A., Cruz, O.L.M., Colli, B.O., Andrade, M.J., Rollin, G.A.F.S., Schwannoma vestibular: Apresentação atípica (1995) J Bras Neurosurg, 6 (2), pp. 41-48Sousa LCA, Piza MRT, Costa SS, Ferez M, Colli BO. Electrophysiologic Monitoring (ABR) of Coma Status,: 99th Meeting of the American Academy of Otolaryngology. Head and Neck Surgery, New Orleans, USA1995Coser, P.L., Menon, A.D., Electrophysiological study of auditory pathways and the vestibular system in tumor pathology of the 8th cranial nerve and of the cerebellopontile angle (1981) Rev Laryngol Otol Rhinol (Bord), 102 (5-6), pp. 239-24
Ecological Invasion, Roughened Fronts, and a Competitor's Extreme Advance: Integrating Stochastic Spatial-Growth Models
Both community ecology and conservation biology seek further understanding of
factors governing the advance of an invasive species. We model biological
invasion as an individual-based, stochastic process on a two-dimensional
landscape. An ecologically superior invader and a resident species compete for
space preemptively. Our general model includes the basic contact process and a
variant of the Eden model as special cases. We employ the concept of a
"roughened" front to quantify effects of discreteness and stochasticity on
invasion; we emphasize the probability distribution of the front-runner's
relative position. That is, we analyze the location of the most advanced
invader as the extreme deviation about the front's mean position. We find that
a class of models with different assumptions about neighborhood interactions
exhibit universal characteristics. That is, key features of the invasion
dynamics span a class of models, independently of locally detailed demographic
rules. Our results integrate theories of invasive spatial growth and generate
novel hypotheses linking habitat or landscape size (length of the invading
front) to invasion velocity, and to the relative position of the most advanced
invader.Comment: The original publication is available at
www.springerlink.com/content/8528v8563r7u2742
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