Petroleomics By Electrospray Ionization Ft-icr Mass Spectrometry Coupled To Partial Least Squares With Variable Selection Methods: Prediction Of The Total Acid Number Of Crude Oils.

Negative-ion mode electrospray ionization, ESI(-), with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was coupled to a Partial Least Squares (PLS) regression and variable selection methods to estimate the total acid number (TAN) of Brazilian crude oil samples. Generally, ESI(-)-FT-ICR mass spectra present a power of resolution of ca. 500,000 and a mass accuracy less than 1 ppm, producing a data matrix containing over 5700 variables per sample. These variables correspond to heteroatom-containing species detected as deprotonated molecules, [M - H](-) ions, which are identified primarily as naphthenic acids, phenols and carbazole analog species. The TAN values for all samples ranged from 0.06 to 3.61 mg of KOH g(-1). To facilitate the spectral interpretation, three methods of variable selection were studied: variable importance in the projection (VIP), interval partial least squares (iPLS) and elimination of uninformative variables (UVE). The UVE method seems to be more appropriate for selecting important variables, reducing the dimension of the variables to 183 and producing a root mean square error of prediction of 0.32 mg of KOH g(-1). By reducing the size of the data, it was possible to relate the selected variables with their corresponding molecular formulas, thus identifying the main chemical species responsible for the TAN values.

Evaluation Of Characteristic-to-total Spectrum Ratio: Comparison Between Experimental And A Semi-empirical Model.

Primary X-ray spectra were measured in the range of 80-150kV in order to validate a computer program based on a semiempirical model. The ratio between the characteristic and total air Kerma was considered to compare computed results and experimental data. Results show that the experimental spectra have higher first HVL and mean energy than the calculated ones. The ratios between the characteristic and total air Kerma for calculated spectra are in good agreement with experimental results for all filtrations used.

The Total Synthesis Of (-)-cryptocaryol A.

A stereoselective total synthesis of (-)-cryptocaryol A () is described. Key features of the 17-step route include the use of three boron-mediated aldol reaction-reduction sequences to control all stereocenters and an Ando modification of the Horner-Wadsworth-Emmons olefination that permitted the installation of the Z double bond of the α-pyrone ring.

A síntese da amônia: alguns aspectos históricos

The ammonia synthesis from its elements plays an important role in the survival of humankind. A short historical development of discoveries of the nitrogen cycle, the nitrogen sources for agriculture and the ammonia synthesis (in laboratory and industry) are presented. Some brief aspects of nitrogen chemistry are described. Short biographies of Fritz Haber and Carl Bosch, the main persons in this epopee, are also presented.

Determinação de açúcar total em café cru por espectroscopia no infravermelho próximo e regressão por mínimos quadrados parciais

In this work a fast method for the determination of the total sugar levels in samples of raw coffee was developed using the near infrared spectroscopy technique and multivariate regression. The sugar levels were initially obtained using gravimety as the reference method. Later on, the regression models were built from the near infrared spectra of the coffee samples. The original spectra were pre-treated according to the Kubelka-Munk transformation and multiplicative signal correction. The proposed analytical method made possible the direct determination of the total sugar levels in the samples with an error lower by 8% with respect to the conventional methodology.

Síntese de complexo ferro(II)-nitrogênio: abordagem dos conceitos de reatividade e retro-doação para alunos de graduação em química

There has been a considerable interest in coordination complexes of molecular nitrogen (N2), partly due to a possible relationship between such complexes and the nitrogen activation process in nature. The present paper describes the synthesis and infrared spectroscopic characterization of an iron-nitrogen derivative with ethylenediamine-N,N,N',N'-tetraacetate (edta) as an experiment for an undergraduate course. The topics covered here include synthesis, reactivity and spectroscopy.

Síntese e estudo de ortossilicatos de zinco luminescentes com aplicação da técnica sol-gel

Usually, the concepts of the Sol-Gel technique are not applied in experimental chemistry courses. This work presents a feasible experiment for chemistry instruction, which involves the synthesis of luminescent materials - Zn2SiO4, with and without Mn2+ as a dopant - by the Sol-Gel technique. The obtained materials were analyzed by scanning electron microscopy, X-Ray diffraction, IR spectroscopy and luminescence measures by UV-vis spectroscopy. The results allow the students to confirm the luminescent properties of the zinc orthosilicate luminophores as well as the structural features expected from literature data.

Curiosidades sobre a reação aldólica utilizada como etapa chave na síntese Brasileira dos ácidos pterídicos A e B

This work describes an overview of our synthesis of pteridic acids A and B and discloses some interesting results related to the lithium enolate-mediated aldol reaction used as key step to set up the C5-C15 fragment of these natural products. This first example, as far we know, of an aldol reaction between a chiral enolate of a (Z) enone and a chiral aldehyde has driven us to a series of experiments showing the remarkable relation between enolization selectivity and reaction conditions.

Análise epidemiológica das fraturas acetabulares

This aim of this work was to carry out an epidemiological study on acetabular fractures in the city of Campinas and surrounds, in view of the few published papers on this subject. Medical files with a diagnosis of acetabular fracture between the years 2004 and 2008 that were made available by the Medical Archiving Service of Hospital das Clínicas, State University of Campinas (UNICAMP) were analyzed by six observers. Data on patients' ages, sex, side affected by the fracture, mechanism of injury, material used for synthesis, complications of the operation, associated fractures, length of hospitalization before and after the surgery, time of total internment and number of physiotherapy sessions before and after the surgery were gathered. It was observed in this population that the left side was more affected; the mechanism of injury that most often caused this type of fracture was automobile accidents; injuries to the sciatic nerve were the commonest surgical complications; and the synthesis material most used was reconstruction plates.

Efeito de baixas doses de radiação X em feridas suturadas e não suturadas - estudo experimental em ratos

The present work evaluated the effect of low doses of X-irradiation on the repairing process of sutured and nonsutured skin wounds in rats. For that, rats underwent a surgical proceedure, in which a 20 x 5-millimeter rectangular wound approximately 2-millimeter-deep was made in the dorsal region of each animal, and were divided in four groups: nonirradiated nonsutured; irradiated nonsutured ; nonirradiated sutured and irradiated sutured. The animals under irradiation were protected, during exposure, with a 2-millimeter-thick lead apron in such a way that only the incision was irradiated. Each animal was submitted to 18 seconds of exposure, undergoing a total of 7.4 rads. The evaluation of the effects of X-rays on the repairing process was carried out through microscopic observation by means of hematoxylin-eosin staining for morphological evaluation, and silver impregnation under polarized light for the observation of collagen synthesis. The results have shown that X-irradiation has caused delay in the repairing process, but it did not stop its development. The irradiated nonsutured group was considered to show the greater delay when compared with the other groups.

Tradução, adaptação cultural e validação do questionário Body image After Breast Cancer para a língua portuguesa do Brasil

Universidade Estadual de Campinas . Faculdade de Educação Física