73 resultados para lco


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Organic crystals possess extremely large optical nonlinearity compared to inorganic crystals. Also organic compounds have the amenability for synthesis and scope for introducing desirable characteristics by inclusions. A wide variety of organic materials having electron donor and acceptor groups, generate high order of nonlinearity. In the present work, a new nonlinear optical crystal, L-citrulline oxalate (LCO) based on the aminoacid L-citrulline was grown using slow evaporation technique. Structural characterization was carried out by single crystal XRD. It crystallizes in the noncentrosymmetric, orthorhombic structure with space group P21 P21 P21. Functional groups present in the sample were identified by Fourier transform infra red (FTIR) and FT-Raman spectral analysis. On studying the FTIR and Raman spectra of the precursors L-citrulline and oxalic acid, used for growing L-citrulline oxalate crystal, it is found that the significant peaks of the precursors are present in the spectra of the L-citrulline oxalate crystal . This observation along with the presence of NH3 + group in the spectra of L-citrulline oxalate, confirms the formation of the charge transfer complex

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El PAP (Proyecto de Aplicación Práctica) propone un plan de fortalecimiento empresarial para la Fundación Cine Sinú, en torno a la creación, el desarrollo y la promoción de proyectos artísticos, educativos y culturales en el área audiovisual, todos ellos encaminados a fortalecer procesos de transformación social en la región Caribe colombiana y las diferentes comunidades del país.

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The WAT is the temperature at the beginning of the appearance of wax crystals. At this temperature the first wax crystals are formed by the cooling systems paraffin / solvents. Paraffins are composed of a mixture of saturated hydrocarbons of high molecular weight. The removal of petroleum from wells and the production lines means a surcharge on produced oil, thus solubilize these deposits formed due to modifications of thermodynamics has been a constant challenge for companies of oil exploration. This study combines the paraffin solubilization by microemulsion systems, the determination of WAT systems paraffin / solvent and performance of surfactant in reducing the crystallization. We used the methods: rheological and the photoelectric signal, validating the latter which was developed to optimize the data obtained due to sensitivity of the equipment used. Methods developed for description of wax precipitation are often in poor agreement with the experimental data, they tend to underestimate the amount of wax at temperatures below the turbidity point. The Won method and the Ideal solution method were applied to the WAT data obtained in solvent systems, best represented by the second interaction of Won method using the solvents naphtha, hexane and LCO. It was observed that the results obtained by WAT photoelectric signal when compared with the viscosity occur in advance, demonstrating the greatest sensitivity of the method developed. The ionic surfactant reduced the viscosity of the solvent systems as it acted modifying the crystalline structure and, consequently, the pour point. The curves show that the WAT experimental data is, in general, closer to the modeling performed by the method of Won than to the one performed by the ideal solution method, because this method underestimates the curve predicting the onset of paraffin hydrocarbons crystallization temperature. This occurs because the actual temperature measured was the crystallization temperature and the method proposes the fusion temperature measurement.

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INTRODUÇÃO: Recém-nascidos (RN) prematuros apresentam elevada morbidade respiratória e necessidade de ventilação mecânica, assim, a fisioterapia respiratória é parte integrante da assistência neonatal. Objetivo: Comparar os efeitos da fisioterapia respiratória convencional (FRC) versus aumento do fluxo expiratório (AFE), na saturação de O2 (SpO2), freqüência cardíaca (FC) e na freqüência respiratória (FR) em prematuros no período pós-extubação. Método: Ensaio clínico randomizado realizado na UTI Neonatal do Hospital das Clínicas de BotucatuUNESP, comparando duas técnicas fisioterapêuticas, aplicadas em recém-nascidos prematuros, nas primeiras 48 horas pós-extubação. Para a análise estatística foram utilizados o teste t Student, Mann-Whitney, Qui-quadrado e o teste exato de Fisher, com nível de significância em 5%. Resultados: Os dois grupos de estudo: Grupo FRC (n= 20) e grupo AFE (n= 20), não diferiram quanto à idade gestacional (média de 28 semanas) e peso de nascimento (média de 1100 gramas). em ambos os grupos a síndrome do desconforto respiratório (SDR) foi o principal diagnóstico. A mediana da idade no início da fisioterapia foi de sete dias no grupo AFE e 11 dias na FRC. Ambas as técnicas produziram aumento significativo da SpO2 aos 10 e 30 minutos, sem alterações na FR. A FC aumentou significativamente após a FRC e não se alterou após o AFE. Conclusão: Os resultados sugerem que o AFE é menos estressante que a FRC e pode ser aplicado em prematuros no período pós-extubação. Nestes recém-nascidos o AFE parece ser seguro e benéfico a curto prazo.

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Caste determination in Trigona spinipes Fabricius (Hymenoptera, Apidae, Meliponini) is trophogenic. Larvae that eat about 360 mu l of food become queens, while those who consume 36 mu l develop into workers. We studied the effect of larval nutrition on the number and length of ovarioles and on ovarian development in fifth instar larvae, white eyed, pink eyed and black-eyed pupae as well as newly emerged adults. All larvae have four ovarioles per ovary, while in queen pupae this number ranged from 8 to 15. Cyst formation, the cell death and other characteristics of ovary morphogenesis were the same regardless of the quantity of food consumed. These results are discussed in relation to caste differentiation in other bees.

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An approximate expression is constructed for the energy of an anharmonic potential with centrifugal barrier. In order to obtain such an analytical expression, the quasi-exact solvability is used and then a fitting of these exact solutions is done.

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The laser Welding process was introduced into dentistry by the end of the 1980s, resulting on a great impulse to that area with the development of cheaper and smaller equipment, using simpler technique. This allowed greater use of that process on the confection of prostheses compared to the brazing process since the heat source for that process is a concentrated light beam of high power, which minimizes distortion problems on the prosthetic pieces. Ag-Pd-Au-Cu alloy used on the confection of dental implant prostheses was observed before and after subjection to the laser welding process. The microstructure was analyzed with the. use of optic microscopy and the corrosion resistance was studied by the traditional electrochemical techniques and by electrochemical impedance, under environmental conditions simulating the aggressiveness found in the mouth cavity. A structural change was detected on the weld area, which presented a refined microstructure deriving from the high-speed cooling. The base metal out of the weld area presented a fusion coarse microstructure. The electrochemical essays showed differences on the potentiodynamic polarization behavior in both weld and metal base areas, indicating superior corrosion resistance in the weld area. The impedance spectra were characterized by capacitive distorted components, presenting linear impedance in the low frequencies area. (C) 2002 Elsevier B.V. B.V. All rights reserved.

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This research presents the results of a cephalometric radiography study, in frontal norm, that was used to measure the possible linear correlations between several linear dimensions of the face, in a sample of a 140 caucasian brazilians, with an average age of 20 years, who were distributed in 2 groups as follows: Control group - formed of 35 males and 35 females, with no apparent facial deformities and with dental oclusion, not necessarily, in Angle's Class I; Unilateral cleft lip and palate group - formed of 35 males and 35 females with surgical correction of the up in the first year and of the palate until the third year of life, without orthodontic treatment. ln each teleradiography, the following parameters were measured using a computer: - Lateral orbit width or external orbit width (LOe) - Medial orbit width or internal orbit width (LOI) - Zygomatic width or facial width (LZI) - Mastold width (LMa) - Maxilar width (LMx) - Nasal width (LNa) - Condilar width (LCo) - Antigonial width (LGa) The values obtained were treated statistically using quantitative analysis (arithmetic mean, standard deviation, standard mean error, Person's variation factor and Pearson factor linear correlation). Theirs significance was established by Student's t test. The Pearson factor linear correlations determined between transverse linear cephalometric width dimensions of face in frontal norm for individuals of both groups and sex, with an average age of 20 years, were: ...

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The removal of aromatic hydrocarbons from diesel has received considerable attention after environmental regulations that require petroleum refiners to raise cetane number and to limit aromatics in diesel fuel in order to improve combustion efficiency and reduce particulate and NOx emissions. An alternative is blending with Fischer–Tropsch (FT) gas-to-liquid diesel fuel; however, this option may not be economically viable solution in case of extensive blend. Another alternative is to incorporate in the diesel pool a greater fraction of the so-called light cycle oil (LCO). Due to its high aromatics content and its low cetane number (typically between 20 and 30), the incorporation of LCO may have a negative impact on the quality of diesel. Current technologies for LCO improvement are based on hydrogenation to adjust both sulphur and cetane number but while an important fraction of the aromatics present in LCO can be saturated in a deep hydrogenation process, the cetane number may still be lower than the target values specified in diesel legislations, so further upgrading is needed. An interesting technology for improving the cetane number of diesels and maintaining meanwhile high diesel yields is achieved by combining a complete hydrogenation process with a selective ring opening (SRO) reaction of the naphthenic rings. The SRO can be defined as naphthene ring-opening to form compounds with high cetane number, but without any carbon losses. Controlling the interconversion of six- and five- membered rings via an acid-catalyzed ring-contraction step is also of great importance, since selective conversion of six-membered to five-membered naphthene rings greatly influences ring-opening rates and selectivity. High intrinsic activity may be enhanced by deposition of noble metals on acidic, high surface area supports, because it is possible to arrange close proximity of the metal and acid sites. Moreover, in large-pore supports, the diffusion resistance of liquid reactants into the pores is minimized. In addition to metal centres, the acid sites of support also plays role in aromatics hydrogenation. However, the functions of different kinds of acid sites (Brønsted vs. Lewis acidity), and their optimal concentrations and strengths, remain unclear. In the present study we investigated the upgrading of an aromatic-rich feedstock over different type of metal supported on mesoporous silica-alumina. The selective hydrogenolysis and ring opening of tetrahydronaphthalene (THN or tetralin) was carried out as representative of LCO fractions after deep hydrogenation process. In this regards the aim of this study is to evaluate both the effect of metals and that of the supports characterized by different acid distribution and strength, on conversion and selectivity. For this purpose a series of catalysts were prepared by impregnation. The catalysts were characterized and conversion tests of THN were performed in a lab-scale plant operating in the pressure range from 7.0-5.0 MPa and in the temperature range from 300 to 360°C.

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Elena Makarova traces how the concept of intercultural education in German-speaking European countries promotes the inclusion of courses in the Language and Culture of Origin (LCO) for immigrant youth in the school curriculum of host countries. Such courses are assumed to have positive effects on the development of immigrant youth in the host country. Particularly, it has been suggested that participation in LCO courses increases the self-esteem of immigrant youth, facilitates the development of their bicultural identity and improves their integration in the host society. However, there is a lack of empirical evidence on the nature of the effects of LCO course attendance on the acculturation of immigrant youth and their cultural identity. Accordingly, the aim of the study detailed in the chapter is to examine the impact of immigrant youth’s attitudes towards LCO courses and of their attendance of such courses on their acculturation and cultural identity.

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Deep Sea Drilling Project Site 563, located on the west flank of the northern Mid-Atlantic Ridge, recovered a long Miocene section from which magnetostratigraphic and isotopic stratigraphy are available. Quantitative analyses of calcareous nannofossil assemblages have been performed in the Lower and Middle Miocene sediments from Site 563. The abundance patterns of the identified species allow us to determine several bioevents for this time interval. The recognized biohorizons, related to the available magnetostratigraphy, provide new data on the biostratigraphic value of many species and on the synchroneity of the events over a wide geographic area. Relations with the oxygen isotope stratigraphy are also reported. Sphenolith distribution is examined in particular detail due to their biostratigraphic importance in the Early Miocene. In particular the recently described species Sphenolithus procerus, Sphenolithus tintinnabulum and Sphenolithus multispinatus can be useful to subdivide the Lower Miocene zones NN2 and NN3. A large variety of Reticulofenestra pseudoumbilicus has been identified within zones NN6 and NN7.

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Ocean Drilling Program Leg 167 represents the first time since 1978 that the North American Pacific margin was drilled to study ocean history. More than 7500 m of Quaternary to middle Miocene (14 Ma) sediments were recovered from 13 sites, representing the most complete stratigraphic sequence on the California margin. Diatoms are found in most samples in variable abundance and in a moderately well-preserved state throughout the sequence, and they are often dominated by robust, dissolution-resistant species. The Neogene North Pacific diatom zonation of Yanagisawa and Akiba (1998, doi:10.5575/geosoc.104.395) best divides the Miocene to Quaternary sequences, and updated ages of diatom biohorizons estimated based on the geomagnetic polarity time scale of Cande and Kent (1995, doi:10.1029/94JB03098) are slightly revised to adjust the differences between the other zonations. Most of the early middle Miocene through Pleistocene diatom datum levels that have been proven to be of stratigraphic utility in the North Pacific appear to be nearly isochronous within the level of resolution constrained by sample spacing. The assemblages are characterized by species typical of middle-to-high latitudes and regions of high surface-water productivity, predominantly by Coscinodiscus marginatus, Stephanopyxis species, Proboscia barboi, and Thalassiothrix longissima. Latest Miocene through Pliocene assemblages in the region of the California Current, however, are intermediate between those of subarctic and subtropical areas. As a result, neither the existing tropical nor the subarctic (high latitude) zonal schemes were applicable for this region. An interval of pronounced diatom dissolution detected throughout the Pliocene sequence apparently correspond to a relatively warmer paleoceanographic condition resulting in a slackening of the southward flow of the California Current.

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Quantitative distributions of calcareous nannofossils are analysed in the early-middle Pleistocene at the small Gephyrocapsa and Pseudoemiliania lacunosa zone transition in deep-sea cores from the Mediterranean Sea and North Atlantic Ocean (Ocean Drilling Program [ODP] Sites 977, 964 and 967, Deep Sea Drilling Project [DSDP] Site 607). The temporal and spatial mode of occurrence of medium-sized gephyrocapsids and reticulofenestrids has been examined to refine biostratigraphic constraints and evaluate possible relationships of stratigraphic patterns to environmental changes during a period of global climatic deterioration. The timing of bioevents has been calibrated using high-resolution sampling and correlation to the delta18O record in chronologically well-constrained sections. Newly identified events and ecostratigraphical signals enhance the stratigraphic resolution at the early-middle Pleistocene. The first occurrence (FO) of intermediate morphotypes between Pseudoemiliania and Reticulofenestra (Reticulofenestra sp.) is proposed as a reliable event within marine isotope stage (MIS) 35 or at the MIS 35/34 transition. The distribution of Reticulofenestra asanoi is characterized by rare and scattered occurrences in its lowest range, but the first common occurrence (FCO) is consistently identified at MIS 32 or 32/31; the last common occurrence (LCO) of the species is a distinctive event at MIS 23. In the studied interval, Gephyrocapsa omega dominates among medium-sized Gephyrocapsa. The FO of G. omega and contemporaneous re-entry of medium-sized gephyrocapsids at the lower-middle Pleistocene transition are diachronous between the Atlantic Ocean and Mediterranean Sea and from the western to eastern Mediterranean. In the Mediterranean, the LO of G. omega falls at MIS 15, insolation cycle 54 and is isochronous among the sites. Abundance fluctuations of G. omega show notable relations to early-middle Pleistocene climate changes; they considerably increase in abundance at the interglacial stages, suggesting warm water preferences. Gephyrocapsa omega temporarily disappears during the glacial MIS 22 and MIS 20. Above MIS 20, an impoverishment in G. omega and in the total abundance of medium-sized gephyrocapsids occurs. A decrease in abundance of G. omega is observed between the western Site 977 and the easternmost Site 967 in the Mediterranean Sea, as a possible response to high salinity and/or low nutrient content. Possible environmental influences on the distribution of R. asanoi and of Reticulofenestra sp. are discussed.

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Shipboard investigation of magnetostratigraphy and shore-based investigation of diatoms and calcareous nannofossils were used to identify datum events in sedimentary successions collected at Ocean Drilling Program (ODP) Leg 201 Site 1225. The goal was to extend the magnetic record previously studied at the same site, ODP Leg 138 Site 851, and provide a comprehensive age model for Site 1225. Two high-magnetic intensity zones at 0-70 and 200-255 meters below seafloor (mbsf) were correlated with lithologic Subunits IA and IC in Hole 1225A. Subunit IA (0-70 mbsf) contains the magnetic reversal record until the Cochiti Subchronozone (3.8 Ma) and has a sedimentation rate of 1.7 cm/k.y. This agrees with previous work done at Site 851. Subunit IC (200-255 mbsf) was not sampled at Site 851. Diatom and nannofossil biostratigraphy constrained this subunit, and we found it to contain the magnetic reversal record between Subchrons C4n.2r and C5n.2n (8.6-9.7 Ma), yielding a sedimentation rate of 2.7 cm/k.y. Biostratigraphy was used to establish the sedimentation rates within Subunits IB and ID (70-200 mbsf and 255-300 mbsf, respectively). These subunits had higher sedimentation rates (~3.4 cm/k.y.) and coincide with the late Miocene-early Pliocene biogenic bloom event (4.5-7 Ma) and the Miocene global cooling trend (10-15 Ma). High biogenic productivity associated with these subunits resulted in the pyritization of the magnetic signal. In lithologic Subunit ID, basement flow is another factor that may be altering the magnetic signal; however, the good correlation between the biostratigraphy and magnetostratigraphy indicates that the magnetic record was locked-in near the seafloor and suggests the age model is robust.