990 resultados para PENNING TRAP
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Pós-graduação em Odontologia - FOA
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The Rose-ringed parakeet (Psittacula krameri [Scopdi]) has been reported (Roberts, 1974; Bashir, 1978; Beg, 1978; and DeGrazio, 1978) as a serious bird pest of maize, sunflower, rape seeds, and fruit crops, particularly citrus, mangoes, and guavas, in Pakistan. Estimated annual losses to maize grown for seed alone amount to about 97,000 tons, worth about Pak. Rs. 150 million or US $15 million (Roberts, 1978). Paradoxically, this handsome bright green parakeet is highly esteemed in the pet trade; and limited numbers are also marketed locally and sometimes exported to neighboring countries, particularly the Arab Gulf Emirates, as caged pets. Traditional control methods aimed at scaring or chasing birds from the crops, usually with noise-making devices, are costly; furthermore, they have largely been unsuccessful and time consuming because they require human patrolling before and after normal working hours. They provide at best only temporary relief. The aim of this study was to develop a new decoy trap based on the Modified Australian Crow Trap (MAC), which we propose to call the PAROTRAP, and to evaluate its effectiveness and potential in capturing live parakeets in the field as a possible solution to the parakeet problem, as well as promoting the economic exploitation of trapped parakeets for the pet trade. The study was undertaken during March and June 1979 as a part of the UNDP/FAO Project No. PAK/71/554, assisting Pakistan Vertebrate Pest Control Centre in developing and improving control techniques to prevent or reduce bird damage to important crops. Our earlier trials showed that parakeets could be induced to enter a conventionally designed MAC trap, and that after some time they learned how to escape from it. Therefore, a series of minor modifications were introduced and field tested.
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Workplace accidents involving machines are relevant for their magnitude and their impacts on worker health. Despite consolidated critical statements, explanation centered on errors of operators remains predominant with industry professionals, hampering preventive measures and the improvement of production-system reliability. Several initiatives were adopted by enforcement agencies in partnership with universities to stimulate production and diffusion of analysis methodologies with a systemic approach. Starting from one accident case that occurred with a worker who operated a brake-clutch type mechanical press, the article explores cognitive aspects and the existence of traps in the operation of this machine. It deals with a large-sized press that, despite being endowed with a light curtain in areas of access to the pressing zone, did not meet legal requirements. The safety devices gave rise to an illusion of safety, permitting activation of the machine when a worker was still found within the operational zone. Preventive interventions must stimulate the tailoring of systems to the characteristics of workers, minimizing the creation of traps and encouraging safety policies and practices that replace judgments of behaviors that participate in accidents by analyses of reasons that lead workers to act in that manner.
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In this work, we have applied sub-Doppler laser cooling to a K-39 magneto-optical trap in order to load a 1071 nm crossed optical dipole trap. The number of atoms loaded into the dipole trap was characterized as a function of the frequency and intensity of the cooling and repump laser beams. For the optimum conditions, the dipole trap has about 2 x 10(6) atoms at an atomic density of 2 x 10(12) cm(-3), with a temperature of about 10 mu K. This technique is a very simple procedure to load a K-39 optical dipole trap without a previous magnetic evaporative cooling step and may find application in other atomic physic systems.
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The recently described genus Philcoxia comprises three species restricted to well lit and low-nutrient soils in the Brazilian Cerrado. The morphological and habitat similarities of Philcoxia to those of some carnivorous plants, along with recent observations of nematodes over its subterranean leaves, prompted the suggestion that the genus is carnivorous. Here we report compelling evidence of carnivory in Philcoxia of the Plantaginaceae, a family in which no carnivorous members are otherwise known. We also document both a unique capturing strategy for carnivorous plants and a case of a plant that traps and digests nematodes with underground adhesive leaves. Our findings illustrate how much can still be discovered about the origin, distribution, and frequency of the carnivorous syndrome in angiosperms and, more generally, about the diversity of nutrient-acquisition mechanisms that have evolved in plants growing in severely nutrient-impoverished environments such as the Brazilian Cerrado, one of the world's 34 biodiversity hotspots.
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Trabajo Finde Título para obtener el Grado en Ciencia del Mar
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In this thesis, I present the realization of a fiber-optical interface using optically trapped cesium atoms, which is an efficient tool for coupling light and atoms. The basic principle of the presented scheme relies on the trapping of neutral cesium atoms in a two-color evanescent field surrounding a nanofiber. The strong confinement of the fiber guided light, which also protrudes outside the nanofiber, provides strong confinement of the atoms as well as efficient coupling to near-resonant light propagating through the fiber. In chapter 1, the necessary physical and mathematical background describing the propagation of light in an optical fiber is presented. The exact solution of Maxwell’s equations allows us to model fiber-guided light fields which give rise to the trapping potentials and the atom-light coupling in the close vicinity of a nanofiber. Chapter 2 gives the theoretical background of light-atom interaction. A quantum mechanical model of the light-induced shifts of the relevant atomic levels is reviewed, which allows us to quantify the perturbation of the atomic states due to the presence of the trapping light-fields. The experimental realization of the fiber-based atom trap is the focus of chapter 3. Here, I analyze the properties of the fiber-based trap in terms of the confinement of the atoms and the impact of several heating mechanisms. Furthermore, I demonstrate the transportation of the trapped atoms, as a first step towards a deterministic delivery of individual atoms. In chapter 4, I present the successful interfacing of the trapped atomic ensemble and fiber-guided light. Three different approaches are discussed, i.e., those involving the measurement of either near-resonant scattering in absorption or the emission into the guided mode of the nanofiber. In the analysis of the spectroscopic properties of the trapped ensemble we find good agreement with the prediction of theoretical model discussed in chapter 2. In addition, I introduce a non-destructive scheme for the interrogation of the atoms states, which is sensitive to phase shifts of far-detuned fiber-guided light interacting with the trapped atoms. The inherent birefringence in our system, induced by the atoms, changes the state of polarization of the probe light and can be thus detected via a Stokes vector measurement.
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The multi-target screening method described in this work allows the simultaneous detection and identification of 700 drugs and metabolites in biological fluids using a hybrid triple-quadrupole linear ion trap mass spectrometer in a single analytical run. After standardization of the method, the retention times of 700 compounds were determined and transitions for each compound were selected by a "scheduled" survey MRM scan, followed by an information-dependent acquisition using the sensitive enhanced product ion scan of a Q TRAP hybrid instrument. The identification of the compounds in the samples analyzed was accomplished by searching the tandem mass spectrometry (MS/MS) spectra against the library we developed, which contains electrospray ionization-MS/MS spectra of over 1,250 compounds. The multi-target screening method together with the library was included in a software program for routine screening and quantitation to achieve automated acquisition and library searching. With the help of this software application, the time for evaluation and interpretation of the results could be drastically reduced. This new multi-target screening method has been successfully applied for the analysis of postmortem and traffic offense samples as well as proficiency testing, and complements screening with immunoassays, gas chromatography-mass spectrometry, and liquid chromatography-diode-array detection. Other possible applications are analysis in clinical toxicology (for intoxication cases), in psychiatry (antidepressants and other psychoactive drugs), and in forensic toxicology (drugs and driving, workplace drug testing, oral fluid analysis, drug-facilitated sexual assault).
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The synthesis of cyclic polystyrene (Pst) with an alkoxyamine functionality has been accomplished by intramolecular radical coupling in the presence of a nitroso radical trap Linear alpha,omega-dibrominated polystyrene, produced by the atom transfer radical polymerization (ATRP) of styrene using a dibrominated initiator, was subjected to chain-end activation via the atom transfer radical coupling (ATRC) process under pseudodilute conditions in the presence of 2-methyl-2-nitrosopropane (MNP). This radical trap-assisted, intramolecular ATRC (RTA-ATRC) produced cyclic polymers in greater than 90% yields possessing < G > values in the 0.8-0.9 range as determined by gel permeation chromatography (GPC). Thermal-induced opening of the cycles, made possible by the incorporated alkoxyamine, resulted in a return to the original apparent molecular weight, further supporting the formation of cyclic polymers in the RTA-ATRC reaction. Liquid chromatography-mass spectrometry (LC-MS) provided direct confirmation of the cyclic architecture and the incorporation of the nitroso group into the macrocycle RTA-ATRC cyclizations carried out with faster rates of polymer addition into the redox active solution and/or in the presence of a much larger excess of MNP (up to a 250:1 ratio of MNP:C-Br chain end) still yielded cyclic polymers that contained alkoxyamine functionality.
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Monobrominated polystyrene (PStBr) chains were prepared using standard atom transfer radical polymerization (ATRP) procedures at 80 °C in THF, with monomer conversions allowed to proceed to approximately 40%. At this time, additional copper catalyst, reducing agent, and ligand were added to the unpurified reaction mixture, and the reaction was allowed to proceed at 50 °C in an atom transfer radical coupling (ATRC) phase. During this phase, polymerization continued to occur as well as coupling; expected due to the substantial amount of residual monomer remaining. This was confirmed using gel permeation chromatography (GPC), which showed increases in molecular weight not matching a simple doubling of the PStBr formed during ATRP, and an increase in monomer conversion after the second phase. When the radical trap 2-methyl-2-nitrosopropane (MNP) was added to the ATRC phase, no further monomer conversion occurred and the resulting product showed a doubling of peak molecular weight (Mp), consistent with a radical trap-assisted ATRC (RTA-ATRC) reaction.
Selective Formation of Diblock Copolymers Using Radical Trap-Assisted Atom Transfer Radical Coupling
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Polystyrene (PSt) radicals and poly(methyl acrylate) (PMA) radicals, derived from their monobrominated precursors prepared by atom transfer radical polymerization (ATRP), were formed in the presence of the radical trap 2-methyl-2-nitrosopropane (MNP), selectively forming PSt-PMA diblock copolymers with an alkoxyamine at the junction between the block segments. This radical trap-assisted, atom transfer radical coupling (RTA-ATRC) was performed in a single pot at low temperature (35 °C), while analogous traditional ATRC reactions at this temperature, which lacked the radical trap, resulted in no observed coupling and the PStBr and PMABr precursors were simply recovered. Selective formation of the diblock under RTA-ATRC conditions is consistent with the PStBr and PMABr having substantially different KATRP values, with PSt radicals initially being formed and trapped by the MNP and the PMA radicals being trapped by the in situ-formed nitroxide end-capped PSt. The midchain alkoxyamine functionality was confirmed by thermolysis of the diblock copolymer, resulting in recovery of the PSt segment and degradation of the PMA block at the relatively high temperatures (125 °C) required for thermal cleavage. A PSt-PMA diblock formed by chain extenstion ATRP using PStBr as the macroinitiator (thus lacking the alkoxyamine between the PSt-PMA segements) was inert to thermolysis. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3619–3626
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Monobrominated polystyrene (PStBr) chains were prepared using standard atom transfer radical polymerization (ATRP) procedures at 80 degrees C in THF, with monomer conversions allowed to proceed to approximately 40%. At this time, additional copper catalyst, reducing agent, and ligand were added to the unpurified reaction mixture, and the reaction was allowed to proceed at 50 degrees C in an atom transfer radical coupling (ATRC) phase. During this phase, polymerization continued to occur as well as coupling; expected due to the substantial amount of residual monomer remaining. This was confirmed using gel permeation chromatography (GPC), which showed increases in molecular weight not matching a simple doubling of the PStBr formed during ATRP, and an increase in monomer conversion after the second phase. When the radical trap 2-methyl-2-nitrosopropane (MNP) was added to the ATRC phase, no further monomer conversion occurred and the resulting product showed a doubling of peak molecular weight (M-p), consistent with a radical trap-assisted ATRC (RTA-ATRC) reaction. (C) 2013 Elsevier Ltd. All rights reserved.
Selective Formation of Diblock Copolymers Using Radical Trap-Assisted Atom Transfer Radical Coupling
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Polystyrene (PSt) radicals and poly(methyl acrylate) (PMA) radicals, derived from their monobrominated precursors prepared by atom transfer radical polymerization (ATRP), were formed in the presence of the radical trap 2-methyl-2-nitrosopropane (MNP), selectively forming PSt-PMA diblock copolymers with an alkoxyamine at the junction between the block segments. This radical trap-assisted, atom transfer radical coupling (RTA-ATRC) was performed in a single pot at low temperature (35 degrees C), while analogous traditional ATRC reactions at this temperature, which lacked the radical trap, resulted in no observed coupling and the PStBr and PMABr precursors were simply recovered. Selective formation of the diblock under RTA-ATRC conditions is consistent with the PStBr and PMABr having substantially different K-ATRP values, with PSt radicals initially being formed and trapped by the MNP and the PMA radicals being trapped by the in situ-formed nitroxide end-capped PSt. The midchain alkoxyamine functionality was confirmed by thermolysis of the diblock copolymer, resulting in recovery of the PSt segment and degradation of the PMA block at the relatively high temperatures (125 degrees C) required for thermal cleavage. A PSt-PMA diblock formed by chain extenstion ATRP using PStBr as the macroinitiator (thus lacking the alkoxyamine between the PSt-PMA segements) was inert to thermolysis. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3619-3626