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Tritrichomonas foetus is a protist that causes bovine trichomoniasis and presents a well-developed Golgi. There are very few studies concerning the Golgi in trichomonads. In this work, monoclonal antibodies were raised against Golgi of T. foetus and used as a tool on morphologic and biochemical studies of this organelle. Among the antibodies produced, one was named mAb anti-Golgi 20.3, which recognized specifically the Golgi complex by fluorescence and electron microscopy. By immunoblotting this antibody recognized two proteins with 60 and 66 kDa that were identified as putative beta-tubulin and adenosine triphosphatase, respectively. The mAb 20.3 also recognized the Golgi complex of the Trichomonas vaginalis, a human parasite. In addition, the nucleotide coding sequences of these proteins were identified and included in the T. foetus database, and the 3D structure of the proteins was predicted. In conclusion, this study indicated: (1) adenosine triphosphatase is present in the Golgi, (2) ATPase is conserved between T. foetus and T. vaginalis, (3) there is new information concerning the nucleic acid sequences and protein structures of adenosine triphosphatase and beta-tubulin from T. foetus and (4) the mAb anti-Golgi 20.3 is a good Golgi marker and can be used in future studies.
Discussions of animal intelligence often assume, inappropriately, that intelligence is inherently good. In this case, it has turned out to be generally true. This chapter reviews absolute versus relational learning by suggesting that animals are capable of using either the absolute or relative properties of a stimulus in making discriminations. The ability of animals to develop emergent stimulus classes involving arbitrary stimuli has important implications for human language learning. The task most often used to study memory in animals is delayed matching-to-sample, in which following acquisition of matching-to-sample, a delay is inserted between the offset of the sample and the onset of the comparison stimuli. The accurate assessment of animal intelligence will require vigilance, on the one hand, to evaluate cognitive functioning against simpler accounts and, on the other hand, to determine the conditions that maximally elicit the animal's cognitive capacity.
In order to counteract disasters and emergencies, it is necessary to build cooperation and collaboration among all entities and actors. Field teams of rescuers require support from the State experiencing a disaster. The responses to the earthquake in Haiti demonstrated a lack of cooperation and collaboration and the rescuers encountered concomitant difficulties. Thus, the problems in the field are not only related to natural and technological aspects, but also social and political contexts. It is time to explore the role of the impact of State power on national and international disasters and emergencies. One modern and fruitful instrument for analysis of these complicated social and group processes is Complex Network modeling. Complex Network tools have been applied successfully to understanding and counteracting such threats as they relate to the spread of infectious diseases and/or to terrorist activities. Another significant utilization of the Complex Network approach is to develop good governance, management, and organizational processes in national and corporate landscapes.
Based on a Complex Network Scope, a novel, three-layer network model of public connections for diverse State regimes for further simulation is proposed. Quantitative assessments and practical processes should be implemented for countering global disasters using international and interdisciplinary teams. Contrary to the known hierarchical layer approach for knowledge acquisition, this new model describes an overall national Society Network by dividing the approach into the three layers: (1) Formal (State), as hierarchical governments structures; (2) Informal (presented by different long-term sustainable link groups); and (3) Informal (aquatinters with short term links (“weak ties”).
According to each of these layers, one of three types of network topologies exist: (1) hierarchical; (2) scale-free; and (3) random, respectively.
A variety of models, methods, and computer-aided systems have been used to predict and analyze disasters and emergencies, and manage a pertinent medical response effectively. The list of these instruments traditionally comprises: computerized databases, geographic information systems (GISs), graph theory, complex networks, mathematical programming, simulation, and agent-based modeling. As a rule, each type of those is applied asunder. It makes sense to put in one silo diverse instruments to get multidisciplinary solution with its synergy effect for problems of disaster and emergency medicine.
Within this study, an original, agent-based model was developed. The model combines the advantages of the principal computer-aided instruments and considers all the types of information: semantic, topographical, metric, and topological. The model is severely dynamic, fits to real actors and principally covers all the disaster situation.
In line with the model, a so called Topometric Agent-Based System (TABS) with its key visualization component has been designed. A TABS-specific simulation to investigate behavior of the attacked network of vulnerable actors has been conducted leading to critical findings. It has been shown a severe significance of order within combination of threats: man-made + natural or those of natural + man-made. A well-balanced financial distribution to protect actors of diverse status also has been found.
A TABS similar to GIS focuses on mapping. Topometric Agent-Based System mapping brings an efficient and clear language for information sharing not only within national emergency medical services but between experts from different fields and countries.
Abstract: Several different types of GaAs-AlGaAs heterostructures were grown on Si substrates by MOCVD. The defect density in as-grown samples (~108cm−2) was similar to that of GaAs layers grown directly on Si, and the crystalline quality of the material was observed to improve slightly with post-growth annealing at 900°C. We examined the diffusion of both Si and Zn dopants during this type of annealing and found only a small amount of redistribution of both species. Laser annealing of GaAs-on-Si was also examined as a method of reducing the defect density in the material - we observed substantial improvements in surface quality, but no change in sub-surface crystalline quality.
Epitaxial, lattice-matched GaAs/Ca0.45Sr0.55/F2 heterostructures were grown on Ge(100) substrates by molecular beam epitaxy. The films were analyzed by Rutherford backscattering and secondary ion mass spectroscopy to determine crystallinity and Ge outdiffusion. The Xmin (channeling over random yield) of a 1.5 μm-thick GaAs film grown on the fluoride is 0.075, indicating reasonably good epitaxy. After rapid thermal annealing, the crystallinity of higher-Xmin films improves, and Ge diffuses only 200 A into the fluoride, indicating that a thin fluoride layer is an effective barrier to Ge outdiffusion.
GaAs layers were grown directly on misoriented (2° off (100)→) Si substrates by Metalorganic Chemical Vapor Deposition. The threading dislocation density at the surface of 4 μm thick layers was typically 108cm−2, as determined by both preferential etching and transmission electron microscopy. Rapid thermal annealing (900°C, 10s) improved the crystalline quality of the GaAs near the heterointerface while allowing no detectable Si diffusion into this layer. Two deep electron traps were observed in the undoped GaAs, but were present at a low concentration (∼ 1013 cm−3 ). The (400) x-ray diffraction peak width from the GaAs was significantly reduced with increasing GaAs layer thickness, indicating improved material quality. This is supported by Si implant activation data, which shows higher net donor activity in thicker layers.
Electromagnetic shields and flux concentrators for magnetic sensors could utilize flexible and insulating composites applied using simple thin film deposition methods such as dip-coating, spin-coating, spraying, etc. As the first step towards development of composites with superior performance, efforts focused on isolating nanoparticles with large magnetizations under low fields. In this paper, we provide the results of proof-of-concept studies for two systems: metal-functionalized silicone-based materials (metal-silicone); and, Co-ferrite (Co2+1−xFe2+xFe3+2O4) nanoparticles. The metal-silicone materials studied included a polysiloxane that contained a pendant ferrocene where an optimum saturization magnetization of 5.9 emu/g (coercivity = 11 Oe) was observed. Co-ferrite nanoparticle samples prepared in this study showed unprecendented saturation magnetization (i.e., Ms > 150 emu/g) with low coercivity (Hc ∼ 10 Oe) at room temperature and offer potential application as flux concentrators.
The results of a low temperature (5K) photoluminescence study of hydrogenation of GaAs on InP grown by metal organic chemical vapor deposition are presented. An emission band at ~ 1.4 eV originating from the GaAs/InP interracial region shows a 30 fold increase in intensity relative to the GaAs band edge emission after exposure to hydrogen plasma for 30 min at 250°C. This improvement in intensity is attributed to hydrogen passivation of defects at the heterointerface caused by the large (≈4%) lattice mismatch between GaAs and InP. The passivation effect recovers on annealing the hydrogenated sample at 350°C. Excitation dependence of the ~1.4 eV band suggests that the interfacial region consists of a compositionally graded layer. Further, this band shifts to higher energy on annealing the sample in the temperature range 150-450°C with the hydrogenated sample exhibiting a larger shift than the untreated sample. It is suggested that the annealing induced peak shift arises due to intermixing of the compositionally graded interface and that the degree of intermixing is greater in the hydrogenated sample compared to the untreated sample.
Zirconia and zirconia-yttria coating films and powders obtained by the sol-gel route using a zirconium alkoxide as starting material and acid and neutral catalytic were investigated by the Perturbed Angular Correlations method (PAC), XRD, DTA and TGA. The hyperfine interaction was measured either during heat treatements or after annealing the samples at increasing temperatures up to 1200°C. All samples have presented a high fraction of crystalline phases at low temperatures. The yttria doped cubic zirconia has not shown the phase transition to the monoclinic phase. Pure zirconia powders produced in neutral hydrolysis and zirconia coatings produced in acid catalysis stabilized the tetragonal phase in a high fraction and up to high temperatures.
We apply a number of complementary characterization techniques including electron paramagnetic resonance, optical absorption, and photoluminescence spectroscopies to characterize a wide range of different ZnO phosphor powders. We generally observe a good correlation between the 510-nm green emission intensity and the density of paramagnetic isolated oxygen vacancies. In addition, both quantities are found to peak at a free-carrier concentration ne, of about 1.4 × 1018 cm-3. We also find that the green emission intensity can be strongly influenced by free-carrier depletion at the particle surface, especially for small particles and/or low doping. Our data suggest that the green PL in ZnO phosphors is due to the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band.
We compare the adsorption of 1,1'-biphenyl-4,4'-dimethanethiol (BPDMT) on gold and cobalt surfaces. The molecular orbitals, identified from combined photoemission and inverse photoemission studies, exhibit shifts in binding energies with different deposition methods and substrates. These shifts indicate that this potential molecular dielectric exhibits stronger bonding to cobalt surfaces than gold surfaces.
Semiconducting boron carbide overlayers, formed from the decomposition of orthocarborane and metacarborane have been studied by angle resolved photoemission. The incurrence of surface photovoltage and the photovoltaic process, from the photoemission experiment, reveal band offsets in the orthocarborane multilayer configurations that are invereted relative to single layer configurations. Defect induced gap states which trap charge at the heterostructure interface is used as one explanation of these results. The role of defects is also used to help illuminate why opposite semiconducting type materials are formed from the decomposition of isomer carborane molecules.
Self-healing polymers have experienced rapid technological advancement over the past seven years. They have moved from a conceptual demonstration to practical application in this time frame and have grown from a single design to a generic paradigm for modern materials development. Potential applications of self-healing polymers are quite broad, including microelectronic substrates and encapsulants, polymeric paints and coatings, structural composites, and biomedical devices. In this article, we focus on polymeric systems that heal in an autonomic fashion, that is, automatically and without human intervention. The types of systems under development and the future of this paradigm in advanced materials are discussed.
In several experiments, faster ions were produced from the backside of
solid targets irradiated by powerful laser pulses. The ion acceleration
was considered due to the negative electrostatic sheath formed on the
backside of the target (TNSA), or to the expansion wave starting at the
backside surface, or to the expansion wave and to its embedded
electrostatic rarefaction shock. In this experiment, ions have been
generated by transferring energy to a controlled amount of mass before the
target become transparent by gas dynamic expansion (controlled amount of
mass mode (CAM)). The targets used were thin transparent disks
causally isolated from the holder to trim down, during the
interaction process, unwanted effects due to the surrounding parts. Two
kinds of target corresponding to a different set of parameters were
designed (LARGE and SMALL). Both targets were conceived to survive, in the
actual contrast conditions, to the low power pulse forerunning the giant
laser pulse, bigger margin but lower performances being assigned to LARGE.
For comparison standard square foils under the same focusing conditions,
were also studied (LARGE-LIKE and SMALL-LIKE irradiation).
Two sol-gel derived zirconia powders were prepared at pH = 0.5 and pH = 5.5. They were investigated as a function of temperature using mainly perturbed angular correlation spectroscopy. The aim was to elucidate the relationship between the nanoscopic configurations around Zr4+ ions and the morphology and structure of the powders. The highly porous material resulting from the solution at higher pH could be described mainly by defective and disordered, very hydrolyzed tetragonal arrays. As temperature increased, the amount of these arrays decreased while they became increasingly asymmetric, thus suggesting their superficial localization. The easy removal of hydroxyls led to the early appearance of the monoclinic phase. The gel obtained from the precursor at pH = 0.5 was entirely described by configurations still involving organic residues. After their calcination, the powder underwent a well-defined two-step hydroxyl removal thermal process leading to the crystallization of the tetragonal and the monoclinic phases. The thermal stability of the metastable tetragonal phase in the investigated powders seems to be controlled by their different capability to absorb oxygen.
Powders and coatings of zirconia doped with 2.5 mole% yttria have been produced via the sol-gel route. The phase structure and subsequent thermal evolution in heating and cooling cycles have been investigated using mainly perturbed angular correlations spectroscopy. Thermal analyses and XRD as a function of temperature have also been performed to obtain complementary information. Upon heating, the amorphous gels crystallized into the tetragonal structure and showed the same hyperfine pattern and thermal behavior as observed in tetragonal zirconia obtained by the ceramic route: the two configurations of vacancies around zirconium ions denoted as t1 and t2 forms and their mutual t1 → t2 transformation. While the powder sample exhibited an incipient thermal instability above 1000 °C and underwent completely the t2 form to m–ZrO2 transition during subsequent, gradual cooling below 500 °C, the coating retained the tetragonal phase within the whole temperature range investigated. Hyperfine results suggest that the tetragonal phase stabilization is favored by the highly defective nature of the t1 form and consequently hardened by the availability of oxygen. The PAC derived activation energy for the fast diffusion of the oxygen vacancies inherent to the t2 form was determined as 0.54 ± 0.14 eV.
Yttria-stabilized cubic zirconia powders and coatings produced by the sol-gel method have been investigated by Perturbed Angular Correlation Spectroscopy (PAC). Results indicate that the metastable cubic phase is retained during heating and cooling cycles. The hyperfine interaction that describes this cubic phase, once crystallized, exhibits two components in a constant ratio of 4 : 1. The components represent different vacancy configurations. For the fast movement of oxygen vacancies starting at 750 °C, which is reflected by the damping of the hyperfine pattern, an activation energy of 0.96 eV was determined.