Algoritmo genético em química

Genetic algorithm is an optimization technique based on Darwin evolution theory. In last years its application in chemistry is increasing significantly due the special characteristics for optimization of complex systems. The basic principles and some further modifications implemented to improve its performance are presented, as well as a historical development. A numerical example of a function optimization is also shown to demonstrate how the algorithm works in an optimization process. Finally several chemistry applications realized until now is commented to serve as parameter to future applications in this field.

Constantes de acidez de ácidos dipróticos a partir de titulações potenciométricas: ilustração dos princípios do cálculo através da construção de um algoritmo muito simples

This work describes the creation of an very simple calculation algorithm, based in basic chemical and mathematic principles, for the calculation of weak diprotic acid dissociation constants as, for example, amino acids, from potentiometric titrations. For an easier understanding of the algorithm the logical reasoning of this calculus is schematized in a diagram of blocks. In the second part of the work the algorithm is applied to an Excel calculation sheet to determine the dissociation constants of Nicotinic Acid and Glycine, from the respective potentiometric titration curves. The values obtained using this algorithm are compared with those estimated by Hyperquad2008 (program generally used for this type of calculus) and also with the values of a stability constants database.

Spectrophotometric method for determination of atazanavir sulfate in capsule dosage form

Two sensitive and simple spectrophotmetric methods were developed for determination of Atazanavir Sulfate in capsule dosage form. The first method was based on the oxidative coupling of ATV with 3-Methyl Benzothiazolin-2-one hydrazone (MBTH). The resulting green product had Λmax of 627.3 nm and was stable for 2 h. The second method was based on the reaction between diazotized drug with N-(1-napthyl)ethylenediamine dihydrochloride (NEDA) in neutral medium to yield yellowish orange product which had Λmax of 517.1 nm. The product was stable for 4 h. Both methods were highly reproducible and had been applied to pharmaceutical preparations.

Desenvolvimento de um algoritmo para identificação e correção de spikes em espectroscopia Raman de imagem

Raman imaging spectroscopy is a highly useful analytical tool that provides spatial and spectral information on a sample. However, CCD detectors used in dispersive instruments present the drawback of being sensitive to cosmic rays, giving rise to spikes in Raman spectra. Spikes influence variance structures and must be removed prior to the use of multivariate techniques. A new algorithm for correction of spikes in Raman imaging was developed using an approach based on comparison of nearest neighbor pixels. The algorithm showed characteristics including simplicity, rapidity, selectivity and high quality in spike removal from hyperspectral images.

Use of modified silica gel for concentrating Pb (II) and Cd (II) occurring in form of complex anions

The performance of silica gel, modified by the impregnation with a high molecular weight quaternary amine (triethyl octadecyl ammonium iodide), used for the concentration of heavy metals occurring in water is studied. The material under study captures Cd, Pb, which are capable of forming stable complexes with I- ions.The results obtained about the metal capture, under dynamic conditions, are described and metal ions are removed by desorption with EDTA and quantified by AAS.

Metaheurística algoritmo genético para solução de problemas de planejamento florestal com restrições de integridade

Os objetivos deste trabalho foram desenvolver e testar um algoritmo genético (AG) para a solução de problemas de gerenciamento florestal com restrições de integridade. O AG foi testado em quatro problemas, contendo entre 93 e 423 variáveis de decisão, sujeitos às restrições de singularidade, produção mínima e produção máxima, periodicamente. Todos os problemas tiveram como objetivo a maximização do valor presente líquido. O AG foi codificado em ambiente delphi 5.0 e os testes foram realizados em um microcomputador AMD K6II 500 MHZ, com memória RAM de 64 MB e disco rígido de 15GB. O desempenho do AG foi avaliado de acordo com as medidas de eficácia e eficiência. Os valores ou categorias dos parâmetros do AG foram testados e comparados quanto aos seus efeitos na eficácia do algoritmo. A seleção da melhor configuração de parâmetros foi feita com o teste L&O, a 1% de probabilidade, e as análises foram realizadas através de estatísticas descritivas. A melhor configuração de parâmetros propiciou ao AG eficácia média de 94,28%, valor mínimo de 90,01%, valor máximo de 98,48%, com coeficiente de variação de 2,08% do ótimo matemático, obtido pelo algoritmo exato branch and bound. Para o problema de maior porte, a eficiência do AG foi cinco vezes superior à eficiência do algoritmo exato branch and bound. O AG apresentou-se como uma abordagem bastante atrativa para solução de importantes problemas de gerenciamento florestal.

Estimativa dos componentes do balanço de energia e da evapotranspiração em plantios de eucalipto utilizando o algoritmo sebal e imagem landsat 5 - TM

Variáveis climáticas são essenciais para a compreensão das condições ambientais que influenciam o crescimento e o desenvolvimento vegetal. Nos últimos anos, as pesquisas que utilizam dados climáticos e técnicas de sensoriamento remoto em análises espaço-temporais da demanda por água e energia das plantas têm-se intensificado. O SEBAL (Surface Energy Balance Algorithms for Land) é um dos algoritmos mais destacados em estudos que envolvem estimativas dos fluxos de energia em grandes áreas, e pode ser aplicado com poucas medições de campo. Este trabalho, realizado no Município de Santa Bárbara, Minas Gerais, objetivou estimar os componentes do balanço de energia e, por conseguinte, a evapotranspiração em plantios de eucalipto com aplicação do algoritmo SEBAL e de imagem do sensor TM do satélite Landsat 5. As estimativas foram realizadas para cena do dia 20/06/2003. Considerando apenas as áreas referentes aos plantios de eucalipto (sete anos de idade), foram obtidos valores médios de saldo de radiação (Rn), fluxo de calor no solo (G), fluxo de calor sensível (H), fluxo de calor latente (LE) de 420,12 W m-2, 81,80 W m-2, 149,93 W m-2, 188,39 W m-2, respectivamente. Para a evapotranspiração real horária (ETr h), o valor médio obtido foi de 0,28 mm h-1. As estimativas mostraram-se condizentes com dados da literatura, no entanto pesquisas com maior controle experimental devem ser realizadas.

Variabilidade local e regional da evapotranspiração estimada pelo algoritmo SEBAL

Em face da importância em conhecer a evapotranspiração (ET) para uso racional da água na irrigação no contexto atual de escassez desse recurso, algoritmos de estimativa da ET a nível regional foram desenvolvidos utilizando-se de ferramentas de sensoriamento remoto. Este estudo objetivou aplicar o algoritmo SEBAL (Surface Energy Balance Algorithms for Land) em três imagens do satélite Landsat 5, do segundo semestre de 2006. As imagens correspondem a áreas irrigadas, floresta nativa densa e a Caatinga do Estado do Ceará (Baixo Acaraú, Chapada do Apodi e Chapada do Araripe). Este algoritmo calcula a evapotranspiração horária a partir do fluxo de calor latente, estimado como resíduo do balanço de energia na superfície. Os valores de ET obtidos nas três regiões foram superiores a 0,60 mm h-1 nas áreas irrigadas ou de vegetação nativa densa. As áreas de vegetação nativa menos densa apresentaram taxa da ET horária de 0,35 a 0,60 mm h-1, e valores quase nulos em áreas degradadas. A análise das médias de evapotranspiração horária pelo teste de Tukey a 5% de probabilidade permitiu evidenciar uma variabilidade significativa local, bem como regional no Estado do Ceará.

Associação entre o escore do International Consultation on Incontinence Questionaire: Urinary Incontinence/Short Form e a Avaliação Urodinâmica em mulheres com incontinência urinária

OBJETIVO: Avaliar a correlação entre o International Consultation on Incontinence Questionnaire - Urinary Incontinence/Short Form (ICIQ-UI/SF) e a Avaliação Urodinâmica (AU) em mulheres com incontinência urinária (IU). MÉTODOS: Foram analisados retrospectivamente dados clínicos, AU e escore do ICIQ-UI/SF de 358 mulheres com IU atendidas em clínica privada. O teste de correlação entre ICIQ-UI/SF e os parâmetros urodinâmicos foi o teste de Spearman. Foi utilizada a curva ROC, com os valores de sensibilidade e especificidade dos escores do ICIQ-UI/SF apresentados pelas pacientes, para identificar o valor do questionário que determinasse a presença da alteração urodinâmica estudada. Para o cálculo do valor p foi utilizado o teste do c² ou exato de Fisher. O nível de significância foi de 5% e o software utilizado para análise foi o SAS versão 9.2. RESULTADOS: As pacientes com IU aos Esforços segundo a AU - IUE urodinâmica - representaram 67,3% do total; aquelas com IUE na AU e Hiperatividade Detrusora (HD) - IUM urodinâmica - 16,2%, e as pacientes com HD isolada - HD - 7,3% do total. As pacientes com AU normal representaram 9,2% do total da amostra. Houve associação significativa entre escore ³14 no ICIQ-UI/SF e as pacientes com IUE urodinâmica e IUM urodinâmica. Pacientes com Pressão de Perda ao Esforço (PPE) £90 cmH2O apresentaram escore ao ICIQ-UI/SF³15. O teste de Spearman mostrou correlação inversa fraca entre o escore e a PPE, porém não mostrou correlação entre esse escore e a Capacidade Cistométrica Máxima (CCM) ou com o volume vesical no primeiro desejo miccional. CONCLUSÃO: Houve associação entre o escore do ICIQ-UI/SF e IUE urodinâmica (isolada ou associada à HD); porém não houve associação com a HD isolada. Quanto menor o valor da PPE, maior o escore total do ICIQ-UI/SF. O ICIQ-UI/SF não foi capaz de discriminar o tipo de IU na população estudada.

Prokaryotic expression of a truncated form of bovine herpesvirus 1 glycoprotein E (gE) and its use in an ELISA for gE antibodies

This article describes the expression of a truncated form of bovine herpesvirus 1 (BoHV-1) glycoprotein E (gE) for use as immunodiagnostic reagent. A 651 nucleotide fragment corresponding to the amino-terminal third (217 amino acids) of BoHV-1 gE - that shares a high identity with the homologous BoHV-5 counterpart - was cloned as a 6×His-tag fusion protein in an Escherichia coli expression vector. A soluble protein of approximately 25 kDa purified from lysates of transformed E. coli was recognized in Western blot (WB) by anti-6xHis-tag and anti-BoHV-1 gE monoclonal antibodies. In addition, the recombinant protein was specifically recognized in WB by antibodies present in the sera of cattle seropositive to BoHV-1 and BoHV-5. An indirect ELISA using the expressed protein as coating antigen performed comparably to a commercial anti-gE ELISA and was able to differentiate serologically calves vaccinated with a gE-deleted BoHV-5 strain from calves infected with BoHV-1. Thus, the truncated gE may be useful for serological tests designed to differentiate BoHV-1/BoHV-5 infected animals from those vaccinated with gE-negative marker vaccines.

Variation between three Eremanthus (Asteraceae) species in their ability to form a seed bank

Knowledge on seed bank function is fundamental for understanding the species regeneration patterns. This investigation was carried out to compare the ability of Eremanthus elaeagnus (Mart. ex DC.) Schultz-Bip, E. glomerulatus Less., and E. incanus (Less.) Less. to form a soil seed bank. Seeds (aquenes) of each of these three species were collected, stored in the laboratory and subsequently buried in the same area where they were collected, inside nylon bags. The bags were collected monthly or bimonthly for germination tests under continuous light and also in darkness at 20 °C (E. elaeagnus e E. glomerulatus) and at 25 °C (E. incanus). After 12 months, a further series of tests compared the germination of achenes that had been buried in soil and compared with those stored in the laboratory at 15, 20, 25, 30, 35, and 40 °C. After three months of burial, the seeds of E. elaeagnus and E. glomerulatus failed to germinate, whereas the seeds of E. incanus, even after burial for 18 months, retained germination percentage of between 1% and 30%. After one year stored in laboratory, the seeds of E. glomerulatus were no longer viable and seeds of E. elaeagnus e E. incanus had a germination percentage below that of newly collected seeds. The results showed that E. elaeagnus and E. glomerulatus do not form seed banks while E. incanus may form a small and persistent soil seed bank.

Serum cytokine profile in the subclinical form of visceral leishmaniasis

The factors determining the development or not of visceral leishmaniasis (VL) have not been completely identified, but a Leishmania-specific cellular immune response seems to play a fundamental role in the final control of infection. Few studies are available regarding the production of cytokines in the subclinical form of VL, with only the production of IFN-g and TNF-a known. The aim of the present study was to identify immunological markers for the oligosymptomatic or subclinical form of VL. A prospective cohort study was conducted on 784 children aged 0 to 5 years from an endemic area in the State of Maranhão, Brazil, between January 1998 and December 2001. During 30 consecutive months of follow-up, 33 children developed the oligosymptomatic form of the disease and 12 the acute form. During the clinical manifestations, serum cytokine levels were determined in 27 oligosymptomatic children and in nine patients with the acute form using a quantitative sandwich enzyme immunoassay. In the subclinical form of VL, variable levels of IL-2 were detected in 52.3% of the children, IL-12 in 85.2%, IFN-g in 48.1%, IL-10 in 88.9%, and TNF-a in 100.0%, with the last two cytokines showing significantly lower levels than in the acute form. IL-4 was not detected in oligosymptomatic individuals. Multiple discriminant analysis used to determine the profile or combination of cytokines predominating in the subclinical form revealed both a Leishmania resistance (Th1) and susceptibility (Th2) profile. The detection of both Th1 and Th2 cytokine profiles explains the self-limited evolution accompanied by the discrete alterations observed for the subclinical form of VL.

Cultural adaptation and validation of the "Kidney Disease and Quality of Life - Short Form (KDQOL-SF™ 1.3)" in Brazil

The objective of the present study was to translate the Kidney Disease Quality of Life - Short Form (KDQOL-SF™1.3) questionnaire into Portuguese to adapt it culturally and validate it for the Brazilian population. The KDQOL-SF was translated into Portuguese and back-translated twice into English. Patient difficulties in understanding the questionnaire were evaluated by a panel of experts and solved. Measurement properties such as reliability and validity were determined by applying the questionnaire to 94 end-stage renal disease patients on chronic dialysis. The Nottingham Health Profile Questionnaire, the Karnofsky Performance Scale and the Kidney Disease Questionnaire were administered to test validity. Some activities included in the original instrument were considered to be incompatible with the activities usually performed by the Brazilian population and were replaced. The mean scores for the 19 components of the KDQOL-SF questionnaire in Portuguese ranged from 22 to 91. The components "Social support" and "Dialysis staff encouragement" had the highest scores (86.7 and 90.8, respectively). The test-retest reliability and the inter-observer reliability of the instrument were evaluated by the intraclass correlation coefficient. The coefficients for both reliability tests were statistically significant for all scales of the KDQOL-SF (P < 0.001), ranging from 0.492 to 0.936 for test-retest reliability and from 0.337 to 0.994 for inter-observer reliability. The Cronbach's alpha coefficient was higher than 0.80 for most of components. The Portuguese version of the KDQOL-SF questionnaire proved to be valid and reliable for the evaluation of quality of life of Brazilian patients with end-stage renal disease on chronic dialysis.

An immunohistochemical, clinical and electroneuromyographic correlative study of the neural markers in the neuritic form of leprosy

The nerve biopsies of 11 patients with pure neuritic leprosy were submitted to routine diagnostic procedures and immunoperoxidase staining with antibodies against axonal (neurofilament, nerve growth factor receptor (NGFr), and protein gene product (PGP) 9.5) and Schwann cell (myelin basic protein, S-100 protein, and NGFr) markers. Two pairs of non-adjacent histological cross-sections of the peripheral nerve were removed for quantification. All the fascicles of the nerve were examined with a 10X-ocular and 40X-objective lens. The immunohistochemistry results were compared to the results of semithin section analysis and clinical and electroneuromyographic data. Neurofilament staining was reduced in 100% of the neuritic biopsies. NGFr positivity was also reduced in 81.8%, PGP staining in 100% of the affected nerves, S100 positivity in 90.9%, and myelin basic protein immunoreactivity in 90.9%. Hypoesthesia was associated with decreased NGFr (81.8%) and PGP staining (90.9%). Reduced potential amplitudes (electroneuromyographic data) were found to be associated with reduced PGP 9.5 (63.6%) and nerve fiber neurofilament staining (45.4%) by immunohistochemistry and with loss of myelinated fibers (100%) by semithin section analysis. On the other hand, the small fibers (immunoreactive dots) seen amid inflammatory cells continued to be present even after 40% of the larger myelinated fibers had disappeared. The present study shows an in-depth view of the destructive effects of leprosy upon the expression of neural markers and the integrity of nerve fiber. The association of these structural changes with the clinical and electroneuromyographic manifestations of leprosy peripheral neuropathy was also discussed.

Expression and characterization of an N-truncated form of the NifA protein of Azospirillum brasilense

Azospirillum brasilense is a nitrogen-fixing bacterium associated with important agricultural crops such as rice, wheat and maize. The expression of genes responsible for nitrogen fixation (nif genes) in this bacterium is dependent on the transcriptional activator NifA. This protein contains three structural domains: the N-terminal domain is responsible for the negative control by fixed nitrogen; the central domain interacts with the RNA polymerase σ54 co-factor and the C-terminal domain is involved in DNA binding. The central and C-terminal domains are linked by the interdomain linker (IDL). A conserved four-cysteine motif encompassing the end of the central domain and the IDL is probably involved in the oxygen-sensitivity of NifA. In the present study, we have expressed, purified and characterized an N-truncated form of A. brasilense NifA. The protein expression was carried out in Escherichia coli and the N-truncated NifA protein was purified by chromatography using an affinity metal-chelating resin followed by a heparin-bound resin. Protein homogeneity was determined by densitometric analysis. The N-truncated protein activated in vivo nifH::lacZ transcription regardless of fixed nitrogen concentration (absence or presence of 20 mM NH4Cl) but only under low oxygen levels. On the other hand, the aerobically purified N-truncated NifA protein bound to the nifB promoter, as demonstrated by an electrophoretic mobility shift assay, implying that DNA-binding activity is not strictly controlled by oxygen levels. Our data show that, while the N-truncated NifA is inactive in vivo under aerobic conditions, it still retains DNA-binding activity, suggesting that the oxidized form of NifA bound to DNA is not competent to activate transcription.