986 resultados para 4-LEVEL SYSTEMS
Resumo:
The B3LYP/6-31G (d) density functional theory (DFT) method was used to study molecular geometry, electronic structure, infrared spectrum (IR) and thermodynamic properties. Heat of formation (HOF) and calculated density were estimated to evaluate detonation properties using Kamlet-Jacobs equations. Thermal stability of 3,6,7,8-tetranitro-3,6,7,8-tetraaza-tricyclo [3.1.1.1(2,4)]octane (TTTO) was investigated by calculating bond dissociation energy (BDE) at the unrestricted B3LYP/6-31G(d) level. Results showed the N-NO2 bond is a trigger bond during the thermolysis initiation process. The crystal structure obtained by molecular mechanics (MM) methods belongs to P2(1)/C space group, with cell parameters a = 8.239 Å, b = 8.079 Å, c = 16.860 Å, Z = 4 and r = 1.922 g cm-3. Both detonation velocity of 9.79 km s-1 and detonation pressure of 44.22 GPa performed similarly to CL-20. According to the quantitative standards of energetics and stability, TTTO essentially satisfies this requirement as a high energy density compound (HEDC).
Resumo:
(E)-2-{[(2-Aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butyl-phenol ( 3: ), a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, ¹H-NMR, 13C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL) charge transfer.
Resumo:
The equilibrium geometries of α,α-ditert-butyl-4H-cyclopenta[2,1-b,3;4-b']dithiophene (DBDT) and α,α-ditert-butyl-4H-cyclopenta[2,1-b,3;4-b']dithiophene S-oxide (DBDTO) were studied at the DFT level of theory with a standard 6-311G* basis set. The molecular structures of the DBDT series were more planar than the corresponding DBDTO series, as revealed by dihedral angles. The UV-visible absorption calculated at TD-DFT/6-311G* showed two absorption peaks for all the molecules except C=S and C=O bridged molecules. In DBDTOs, C=S and C=O bridged molecules showed three and four absorption peaks, respectively. The DBDTOs had lower band gaps and longer wavelengths compared to the corresponding DBDTs.
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Biodegradable nanoparticles (NPs) have received considerable attention because of their possible use in the development of strategies for the topical delivery of oils and therapeutic drugs, particularly when drug penetration in dermis is desired. Zein is a prolamine and is a promising material for the design of drug delivery systems. In this study, NPs were prepared with zein and were used to encapsulate and release terpinen-4-ol, which is a therapeutic agent for the treatment of melanoma. The results show that the zein NPs are promising nanostructured systems for the prolonged delivery of T4OL with potential applications in anti-melanoma therapy.
Resumo:
In this work, we report the Biginelli-type reaction between various aldehydes, acetophenones and urea systems in the presence of sulfonic acid functionalized silica (SBA-Pr-SO3H) under solvent-free conditions, which led to 4,6-diarylpyrimidin-2(1H)-ones derivatives. SBA-Pr-SO3H with a pore size of 6 nm was found to be an efficient heterogeneous solid acid catalyst for this reaction which led to high product yields, was environmentally benign with short reaction times and easy handling.
Resumo:
AbstractMany well-established methods for determining the antioxidant capacities in several samples have been described in literature. However, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) are the main two methods that utilize radicals as spectrophotometric probes for analysis. Nevertheless, these methods have certain limitations because of their slower kinetics, solvent polarity effects, the hydrophilicity and lipophilicity of the compounds, chemical costs, etc. In this study, a spectrophotometric method for determining the antioxidant capacity in beverages was developed based on an exploration of the cation radical derived from DEPD. This method was based on the oxidation of aromatic amines with Fe(III) ions at pH 4.0, which leads to their corresponding purple cation radicals (DEPD•+) with λmax values at 500 and 540 nm. The addition of an antioxidant after the formation of the radical leads to a reduction in color intensity that is proportional to the antioxidant concentration in the medium. Results obtained using this method were compared with the Folin-Ciocalteau, ABTS and DPPH methods in terms of applications in wines, teas, and infusions samples. Linear correlation analysis at a 95% confidence level was employed to compare the results, which were in good agreement with a correlation coefficient of r > 0.9000. Thus, the developed method was simple, accurate, and consistent with other assays for the determination of the total amount of phenolic compounds and antioxidant capacity.
Resumo:
The structural and electronic properties of 1-(5-Hydroxymethyl - 4 -[ 5 - (5-oxo-5-piperidin- 1 -yl-penta- 1,3 -dienyl)-benzo [1,3] dioxol- 2 -yl]-tetrahydro -furan-2 -yl)-5-methy l-1Hpyrimidine-2,4dione (AHE) molecule have been investigated theoretically by performing density functional theory (DFT), and semi empirical molecular orbital calculations. The geometry of the molecule is optimized at the level of Austin Model 1 (AM1), and the electronic properties and relative energies of the molecules have been calculated by density functional theory in the ground state. The resultant dipole moment of the AHE molecule is about 2.6 and 2.3 Debyes by AM1 and DFT methods respectively, This property of AHE makes it an active molecule with its environment, that is AHE molecule may interacts with its environment strongly in solution.
Resumo:
Marine traffic is expected to increase rapidly in the future, both in the Baltic Sea and in the Gulf of Finland. As the number of vessels in the area increases, so does the risk of serious marine accidents. To help prevent such accidents in the future, the International Maritime Organization (IMO) has put forth the International Safety Management Code (the ISM Code), which aims to improve the safety of the vessels. The second work package of the Development of maritime safety culture (METKU) project investigates the effects of the ISM Code and potential areas of improvement in maritime safety. The first phase in the work package used a literature review to determine how maritime safety culture could be improved. Continuous improvement, management commitment and personnel empowerment and motivation were found to be essential. In the second phase, shipping companies and administrators were interviewed. It was discovered that especially incident reporting based on continuous improvement was felt to be lacking. This third phase aims to take a closer look at incident reporting and suggest improvements based on the findings. Both the IMO and national legislation encourage shipping companies in incident reporting, and on the national level a shared incident reporting system (ForeSea) is being pushed forward. The objective of this research project was to find out the IMO’s attitude towards incident reporting, to establish a theoretical framework of reference in incident reporting, and to observe how reporting is actually being employed on the seas. Existing incident reporting systems were also researched. The study was carried out using a literature review and the results previously gathered in interviews. The results of phase two were elaborated further for themes relating to incident reporting. According to the findings of this research, the theoretical background of incident reporting dates back to the early 20th century. Although some theories are widely accepted, some have also received criticism. The lack of a concise, shared terminology poses major difficulties in maritime incident reporting and in determining its efficiency. A central finding is the fact that existing incident reporting focuses mostly on information flow away from the ship, whereas the backward information flow is much less planned and monitored. In incident reporting, both nationally and internationally, stakeholders are plenty. The information produced by these parties is scattered, however, and thus not very usable. Based on this research, the centralizing of this information should be made a priority. Traditionally, the success of incident reporting has been determined statistically, from the number of reported incidents. Yet existing reporting systems have not been designed with such statistical analysis in mind, so different methodologies might yield a more comprehensive view. The previous findings of seafarers and management (including shipping companies and administration) having differing views on safety work and safety management were backed up by the results of this study. Seafarers find seamanship and storytelling important, while management wants a more systematic and broad approach on safety matters. The research project was carried out by the Centre for Maritime Studies of the University of Turku, in the Kotka unit (Maritime Logistics Research), with coordination by the Kotka Maritime Research Centre. The major financiers of the project were the European Union and the city of Kotka. The financing authority was the Regional Council of Päijät-Häme. Partners in the project were the shipping companies Finnlines Oyj, Kristina Cruises Oy, Meriaura Oy and VG-Shipping Oy, and the ports of Helsinki, Kotka and Hamina. The partners provided both funding for the project and information for the research.
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Biology is turning into an information science. The science of systems biology seeks to understand the genetic networks that govern organism development and functions. In this study the chicken was used as a model organism in the study of B cell regulatory factors. These studies open new avenues for plasma cell research by connecting the down regulation of the B cell gene expression program directly to the initiation of plasma cell differentiation. The unique advantages of the DT40 avian B cell model system, specifically its high homologous recombination rate, were utilized to study gene regulation in Pax5 knock out cell lines and to gain new insights into the B cell to plasma cell transitions that underlie the secretion of antibodies as part of the adaptive immune response. The Pax5 transcription factor is central to the commitment, development and maintenance of the B cell phenotype. Mice lacking the Pax5 gene have an arrest in development at the pro-B lymphocyte stage while DT40 cells have been derived from cells at a more mature stage of development. The DT40 Pax5-/- cells exhibited gene expression similarities with primary chicken plasma cells. The expression of the plasma cell transcription factors Blimp-1 and XBP-1 were significantly upregulated while the expression of the germinal centre factor BCL6 was diminished in Pax5-/- cells, and this alteration was normalized by Pax5 re-introduction. The Pax5-deficient cells further manifested substantially elevated secretion of IgM into the supernatant, another characteristic of plasma cells. These results for the first time indicated that the downregulation of the Pax5 gene in B cells promotes plasma cell differentiation. Cross-species meta-analysis of chicken and mouse Pax5 gene knockout studies uncovers genes and pathways whose regulatory relationship to Pax5 has remained unchanged for over 300 million years. Restriction of the hematopoietic stem cell fate to produce T, B and NK cell lineages is dependent on the Ikaros and its molecular partners, the closely related Helios and Aiolos. Ikaros family members are zinc finger proteins which act as transcriptional repressors while helping to activate lymphoid genes. Helios in mice is expressed from the hematopoietic stem cell level onwards, although later in development its expression seems to predominate in the T cell lineage. This study establishes the emergence and sequence of the chicken Ikaros family members. Helios expression in the bursa of Fabricius, germinal centres and B cell lines suggested a role for Helios in the avian B-cell lineage, too. Phylogenetic studies of the Ikaros family connect the expansion of the Ikaros family, and thus possibly the emergence of the adaptive immune system, with the second round of genome duplications originally proposed by Ohno. Paralogs that have arisen as a result of genome-wide duplications are sometimes termed ohnologs – Ikaros family proteins appear to fit that definition. This study highlighted the opportunities afforded by the genome sequencing efforts and somatic cell reverse genetics approaches using the DT40 cell line. The DT40 cell line and the avian model system promise to remain a fruitful model for mechanistic insight in the post-genomic era as well.
Resumo:
The objective of the work has been to study why systems thinking should be used in combination with TQM, what are the main benefits of the integration and how it could best be done. The work analyzes the development of systems thinking and TQM with time and the main differences between them. The work defines prerequisites for adopting a systems approach and the organizational factors which embody the development of an efficient learning organization. The work proposes a model based on combination of an interactive management model and redesign to be used for application of systems approach with TQM in practice. The results of the work indicate that there are clear differences between systems thinking and TQM which justify their combination. Systems approach provides an additional complementary perspective to quality management. TQM is focused on optimizing operations at the operational level while interactive management and redesign of organization are focused on optimization operations at the conceptual level providing a holistic system for value generation. The empirical study demonstrates the applicability of the proposed model in one case study company but its application is tenable and possible also beyond this particular company. System dynamic modeling and other systems based techniques like cognitive mapping are useful methods for increasing understanding and learning about the behavior of systems. The empirical study emphasizes the importance of using a proper early warning system.
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In this Thesis I discuss the exact dynamics of simple non-Markovian systems. I focus on fundamental questions at the core of non-Markovian theory and investigate the dynamics of quantum correlations under non-Markovian decoherence. In the first context I present the connection between two different non-Markovian approaches, and compare two distinct definitions of non-Markovianity. The general aim is to characterize in exemplary cases which part of the environment is responsible for the feedback of information typical of non- Markovian dynamics. I also show how such a feedback of information is not always described by certain types of master equations commonly used to tackle non-Markovian dynamics. In the second context I characterize the dynamics of two qubits in a common non-Markovian reservoir, and introduce a new dynamical effect in a wellknown model, i.e., two qubits under depolarizing channels. In the first model the exact solution of the dynamics is found, and the entanglement behavior is extensively studied. The non-Markovianity of the reservoir and reservoirmediated-interaction between the qubits cause non-trivial dynamical features. The dynamical interplay between different types of correlations is also investigated. In the second model the study of quantum and classical correlations demonstrates the existence of a new effect: the sudden transition between classical and quantum decoherence. This phenomenon involves the complete preservation of the initial quantum correlations for long intervals of time of the order of the relaxation time of the system.
Resumo:
Based on a polygenic system of a diploid species, without epistasis, and a population in Hardy-Weinberg equilibrium, without inbreeding and under linkage equilibrium, it can be shown that: (1) the narrow sense heritability at half-sib family level is equal to the square of the correlation coefficient between family mean and the additive genetic value of its common parent; (2) the narrow sense heritability at full-sib family level is equal to the square of the correlation coefficient between family mean and the mean of the additive genetic values of its parents; (3) the narrow sense heritability at Sn family level is exactly equal to the square of the correlation coefficient between family mean and the additive genetic value of its parent only in absence of dominance or when allele frequencies are equal; and (4) the broad sense heritability at full-sib or Sn family level can be used to analyze selection efficiency, since the progeny genotypic mean is, in general, a good indicator of parents, or Sn-1 plant superiority with respect to the frequency of favorable genes.
Resumo:
Nutritional status of eight 1.0 and 4.7 years old clones of Eucalyptus grandis, cultivated in a medium textured Ustults - US - and a Quartzipsamments - PS - soils, in Lençóis Paulista, São Paulo, were evaluated by the Diagnosis and Recommendation Integrated System (DRIS) and Critical Level (CL) methods. Based on multivariate discriminant analysis, the DRIS indices described the nutritional status of trees better in relation to tree age and soil type than in relation to nutrient composition. Spearman's correlation coefficients showed statistically significant relationships between volumetric tree growth and nutrients when applying DRIS indices or foliar nutrient concentrations. However, the DRIS indices indicated a lower number of trees with nutritional deficiencies, in relation to the CL method. According to the CL method, P, S, and Ca were deficient in the majority of the soils and tree age categories. By the DRIS method, Ca was the only deficient nutrient in PS soils, and appeared to be particularly limited in one-year-old trees. In conclusion, the DRIS method was more efficient than the CL method in evaluating the nutritional status of eucalyptus trees.
Resumo:
Systems biology is a new, emerging and rapidly developing, multidisciplinary research field that aims to study biochemical and biological systems from a holistic perspective, with the goal of providing a comprehensive, system- level understanding of cellular behaviour. In this way, it addresses one of the greatest challenges faced by contemporary biology, which is to compre- hend the function of complex biological systems. Systems biology combines various methods that originate from scientific disciplines such as molecu- lar biology, chemistry, engineering sciences, mathematics, computer science and systems theory. Systems biology, unlike “traditional” biology, focuses on high-level concepts such as: network, component, robustness, efficiency, control, regulation, hierarchical design, synchronization, concurrency, and many others. The very terminology of systems biology is “foreign” to “tra- ditional” biology, marks its drastic shift in the research paradigm and it indicates close linkage of systems biology to computer science. One of the basic tools utilized in systems biology is the mathematical modelling of life processes tightly linked to experimental practice. The stud- ies contained in this thesis revolve around a number of challenges commonly encountered in the computational modelling in systems biology. The re- search comprises of the development and application of a broad range of methods originating in the fields of computer science and mathematics for construction and analysis of computational models in systems biology. In particular, the performed research is setup in the context of two biolog- ical phenomena chosen as modelling case studies: 1) the eukaryotic heat shock response and 2) the in vitro self-assembly of intermediate filaments, one of the main constituents of the cytoskeleton. The range of presented approaches spans from heuristic, through numerical and statistical to ana- lytical methods applied in the effort to formally describe and analyse the two biological processes. We notice however, that although applied to cer- tain case studies, the presented methods are not limited to them and can be utilized in the analysis of other biological mechanisms as well as com- plex systems in general. The full range of developed and applied modelling techniques as well as model analysis methodologies constitutes a rich mod- elling framework. Moreover, the presentation of the developed methods, their application to the two case studies and the discussions concerning their potentials and limitations point to the difficulties and challenges one encounters in computational modelling of biological systems. The problems of model identifiability, model comparison, model refinement, model inte- gration and extension, choice of the proper modelling framework and level of abstraction, or the choice of the proper scope of the model run through this thesis.