947 resultados para Diamond cutters
Resumo:
Studies were conducted in apple, Malus domestica Borkhausen and pear, Pyrus communis L. (Rosales: Rosaceae), orchards to evaluate the attractiveness of grey halobutyl septa loaded with 1 (L2) and 10 (Mega) mg of codlemone, 8E,10E-dodecadien-1-ol, 3 mg of pear ester, ethyl (E,Z)- 2,4-decadienoate (DA2313), and 3 mg of pear ester plus 3 mg of codlemone (Combo) to adult codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). All studies were conducted in orchards treated with pheromone mating disruption. All four lures were tested on diamond-shaped sticky traps placed in 60 plots of apple and 40 plots of pears in 2003/04, and in 62 plots of apples and 30 of pears in 2004-05. Combo lures attracted significantly more moths (males + females) than all the others in both years. Comparisons among flights showed significant differences mainly for flight 1 and 2, but not always for flight 3. Mega lures provided no significant improvement compared with L2 lures during both seasons regarding the total number of moths. Combo and DA2313 lures attracted fewer females than males during the whole season. For most sample dates, more virgin than mated females were attracted to Combo lures, except during the third flight, and the overall ratio was 60:40, although the difference was not statistically significant. We conclude that the Combo lures are better indicators of codling moth activity in pheromone treated orchards, regardless of pest population level, when compared with similar lures containing codlemone or pear ester alone.
Resumo:
Rakennustyömaa on yksi vaarallisimpia ja työolosuhteiltaan haastavimpia työpaikkoja. Sisävalmistusvaiheessa ongelmaksi muodostuu töiden tuottama pöly ja melu. Työmaan epäjärjestys ja likaisuus lisäävät tapaturmariskiä. Pölytöntä rakennustyömaata ei ole olemassa ja tästä syystä pölynhallinta muodostuu merkittäväksi tekijäksi pölyn leviämisen rajoittamisessa. Työn tavoitteena oli tutkia teknisiä pölynhallintakeinoja, joilla voidaan vähentää henkilökohtaisen suojauksen tarvetta rakennustyömailla. Pölynhallintaan työmailla voidaan vaikuttaa työtapojen ja -menetelmien valinnalla, töiden vaiheistuksella, kohdepoistoilla, osastoinnilla ja alipaineistuksella. Työssä oli tarkoitus myös verrata ja tutkia erilaisten ja eri työvaiheisiin tarkoitettujen pölynhallintalaitteistojen toimintaa ja niiden toimivuutta pölynhallinnassa. Tämä tutkimus toteutettiin Savocon Oy:n Kuopioon rakennettavan Turontähden rakennustyömaalla huhti- ja toukokuussa 2008. Tutkimusten perusteella tekniset pölynhallintakeinot toimivat kohtalaisen hyvin. Hiomalaitteissa pölynhallinta on tekninen ominaisuus, mutta sen toimivuus riippuu myös siitä, osaako työntekijä hyödyntää pölynhallintaa oikealla tavalla. Toimintaan vaikuttaa se, osaavatko laitteen käyttäjät asettaa imutehon sellaiseksi, että se on riittävän suuri poistamaan pölyn, mutta ei liian suuri haitatakseen työntekoa ja saaden aikaan heikkoa työnjälkeä. Oikeat laiteasetukset opitaan kokeilemalla. Imutehon säätömahdollisuus on erilaisten pintatasoitteiden myötä erityisen tärkeä laiteominaisuus. Timanttihiomalaitteilla saavutetut pölynpoistotehokkuudet olivat kaikki yli 97 prosenttia, kun niiden tehoa verrattiin ilman pölynpoistoa tapahtuvaan timanttihiontaan. Timanttihiontaa ei suositella tehtäväksi ilman pölynpoistotekniikkaa, sillä pölyntuotto on suurta ja pölypitoisuudet nousevat nopeasti hyvin suuriksi ja työntekijöiden altistus pölylle kasvaa. Ilmanpuhdistimien tehot riittivät pienen tilan ilman puhdistamiseen, mutta suurissa tiloissa ja suurissa pitoisuuksissa teho jäi riittämättömäksi. Oikein mitoitettuina ilmanpuhdistimia voidaan suositella kohdepoistolla toimivien laitteiden lisäksi huonetilaan puhdistamaan vähäiset hiukkaspäästöt, joita laitteista tulee. Teollisuusimurien valinnassa huomio tulee kiinnittää moottorin imutehoon, moottorin jäähdytyksen järjestelyyn, pölypussin materiaaliin ja pölypussin tyhjennysmekanismiin. Näillä on suuri merkitys siivoustyön pölyttömämpään lopputulokseen. Tämän työn käyttö markkinointitarkoituksessa ilman tekijän lupaa on kielletty.
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The CORNISH project is the highest resolution radio continuum survey of the Galactic plane to date. It is the 5 GHz radio continuum part of a series of multi-wavelength surveys that focus on the northern GLIMPSE region (10° < l < 65°), observed by the Spitzer satellite in the mid-infrared. Observations with the Very Large Array in B and BnA configurations have yielded a 1.''5 resolution Stokes I map with a root mean square noise level better than 0.4 mJy beam 1. Here we describe the data-processing methods and data characteristics, and present a new, uniform catalog of compact radio emission. This includes an implementation of automatic deconvolution that provides much more reliable imaging than standard CLEANing. A rigorous investigation of the noise characteristics and reliability of source detection has been carried out. We show that the survey is optimized to detect emission on size scales up to 14'' and for unresolved sources the catalog is more than 90% complete at a flux density of 3.9 mJy. We have detected 3062 sources above a 7σ detection limit and present their ensemble properties. The catalog is highly reliable away from regions containing poorly sampled extended emission, which comprise less than 2% of the survey area. Imaging problems have been mitigated by down-weighting the shortest spacings and potential artifacts flagged via a rigorous manual inspection with reference to the Spitzer infrared data. We present images of the most common source types found: H II regions, planetary nebulae, and radio galaxies. The CORNISH data and catalog are available online at http://cornish.leeds.ac.uk.
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The anodic voltammetric behavior of 4-chlorophenol (4-CF) in aqueous solution has been studied on a Boron-doped diamond electrode using square wave voltammetry (SWV). After optimization of the experimental conditions, 4-CF was analyzed in pure and natural waters using a Britton-Robinson buffer with pH = 6.0 as the supporting electrolyte. Oxidation occurs at 0.80 V vs Ag/AgCl in a two-electron process controlled by adsorption of the species. The detection limits obtained were 6.4 µg L-1 in pure water and 21.5 µg L-1 for polluted water taken from a local creek, respectively. The combination of square wave voltammetry and diamond electrodes is an interesting and desirable alternative for analytical determinations.
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After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSAÒ-based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.
Resumo:
This review presents a brief account concerning the production, characterization and evolution of the knowledge in the area of diamond and boron-doped diamond films. The most important methods used for the growth of these films, such as chemical vapor deposition and high pressure/high temperature systems, as well as the several kinds of reactors which can be employed are reviewed. However, larger emphasis is given to the CVD method. Morphological, structural and electric properties of these films, as well as their role in the performance of voltammetric electrodes for electrochemistry and electroanalytical chemistry are also discussed.
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A boron-doped diamond electrode is used for determination of Mn(II) in atmospheric particulate matter by square wave cathodic stripping voltammetry. The analytical curve was linear for Mn(II) concentrations between 5.0 and 37.5 µg L-1, with quantification limit of 3.6 µg L-1. The precision was evaluated by the relative standard deviation, with values between 5.1% and 9.3%. The electrode is free of adsorption, minimizing memory effects. Samples collected in the workplace atmosphere of a foundry had Mn(II) concentrations between 0.4 and 4 µg m-3. No significant differences were observed between the proposed method and inductively coupled plasma optical emission spectroscopy.
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The goal of this work is to show the use of undoped nanodiamond films as a new material for electrochemical and aerospace applications. Correlation between the applications and physico-chemical features of nano and conventional CVD polycrystalline diamond films are presented. An important and innovative application of these nanodiamonds is organic electrosynthesis, including pharmaceutical and water disinfection products, as well as electroanalytical applications, for example, development of biosensors for detection of glucose, glutamate and dopamine. In aeronautics and space developments, these nanodiamonds could be used as electrodes in rechargable batteries and in tribological investigations.
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The use of square-wave voltammetry in conjunction with a cathodically pre-treated diamond electrode for the analytical determination of sodium cyclamate is described. The samples were analyzed as received in a 0.5 mol L-1 H2SO4 solution in the concentration range from 5.0 × 10-5 mol L-1 to 4.1 × 10-4 mol L-1, with a detection limit of 4.8 × 10-6 mol L-1. The RSD was smaller than 1.2 % and the proposed method was applied with success in the determination of sodium cyclamate in several dietary products.
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Gas-phase SiCl3+ ions undergo sequential solvolysis type reactions with water, methanol, ammonia, methylamine and propylene. Studies carried out in a Fourier Transform mass spectrometer reveal that these reactions are facile at 10-8 Torr and give rise to substituted chlorosilyl cations. Ab initio and DFT calculations reveal that these reactions proceed by addition of the silyl cation to the oxygen or nitrogen lone pair followed by a 1,3-H migration in the transition state. These transition states are calculated to lie below the energy of the reactants. By comparison, hydrolysis of gaseous CCl3+ is calculated to involve a substantial positive energy barrier.
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The potentiality of the use of ultrasound radiation in association with a boron-doped diamond electrode was evaluated on the voltammetric determination of the pesticide carbaryl. Improvements in the sensitivity, limit of detection and reproducibility of the measurements were observed due to both, the enhancement of mass transport and the cleaning of the electrode surface provided by ultrasound. Satisfactory recovery levels for carbaryl in pure water (96-98%) and pineapple juice (89-92%) for quiescent and sonovoltammetric methodologies were obtained. These methodologies can be alternative tools for the analyses of pesticides in fruit samples, mainly the insonated condition that improve the analytical performance and dispense intermediary cleanings of the electrode surface.
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Over 50 years, several scientists and industries have developed new alternatives for wastewater treatment and remediation. Recently, electrochemical technology has been largely developed mainly because of its versatility and environmental compatibility. Scientific contributions about role of the electrode material have allowed determining that the influence of material in the selectivity is an important parameter. However, to interpret this behavior, comprehensive physical chemistry models for organics destruction, related to electrochemical phenomena and material surfaces, were proposed in the last decades. So, this paper presents a critical and comprehensive review about the principles and recent mechanism advances in electrocatalysis for wastewater treatment.
Resumo:
The degradation of vinasses in aqueous solution from ethanol industry has been investigated by electrochemical oxidation using a boron doped diamond electrode (BDD). Samples of vinasses were electrolyzed in medium of (0.1 mol L-1) Na2SO4 solutions at controlled potentials of +2.4, +3.0 and +4.0 V (vs. Ag/AgCl) and exhibited considerable reduction of total organic carbon. The cyclic voltammetry studies indicate that the vinasses are oxidized irreversibly over the BDD at 2.0 V (vs. Ag/AgCl) in diffusion controlled process. From the experimental results it is clear that the BDD electrode can be a valuable tool to the electrochemical degradation of vinasses in practical applications
Resumo:
This paper presents the electrolyte influence on deposition and dissolution processes of Cu nanoparticles on boron doped diamond electrodes (BDD). Morphological, structural and electrochemical analysis showed BDD films with good reproducibility, quality and reversible in a specific redox system. Electrodeposition of Cu nanoparticles on DDB electrodes in three different solutions was influenced by pH and ionic strength of the electrolytic medium. Analyzing the process as function of the scan rate, it was verified a better efficiency in 0,5 mol L-1 Na2SO4 solution. Under the influence of the pH and ionic strength, Cu nanoparticles on DDB may be obtained with different morphologies and it was important for defining the desired properties.