Fe3+-SELECTIVE ENHANCED FLUORESCENCE PROBE BASED ON A RHODAMINE DERIVATIVE

A novel Fe3+-selective and turn-on fluorescent probe 1 incorporating a rhodamine fluorophore and quinoline subunit was synthesized. Probe 1 displayed high selectivity for Fe3+ in CH3CN–H2O (95:5 v/v) in the presence of other relevant metal cations. Interaction with Fe3+ in 1:1 stoichiometry could trigger a significant fluorescence enhancement due to the formation of the ring-open form. The fluorescent response images were investigated by a novel Euclidean distance method based on red, green, and blue values. A linear relationship was observed between fluorescence intensity changes and Fe3+ concentrations from 7.3 × 10−7 to 3.6 × 10−5 mol L−1.

INTERACTIONS: DESIGN, IMPLEMENTATION AND EVALUATION OF A COMPUTATIONAL TOOL FOR TEACHING INTERMOLECULAR FORCES IN HIGHER EDUCATION

Intermolecular forces are a useful concept that can explain the attraction between particulate matter as well as numerous phenomena in our lives such as viscosity, solubility, drug interactions, and dyeing of fibers. However, studies show that students have difficulty understanding this important concept, which has led us to develop a free educational software in English and Portuguese. The software can be used interactively by teachers and students, thus facilitating better understanding. Professors and students, both graduate and undergraduate, were questioned about the software quality and its intuitiveness of use, facility of navigation, and pedagogical application using a Likert scale. The results led to the conclusion that the developed computer application can be characterized as an auxiliary tool to assist teachers in their lectures and students in their learning process of intermolecular forces.

ESTUDO DA GLICOSILAÇÃO DO CICLO-HEXANOL COM DIFERENTES DERIVADOS DE D-GLICOSAMINA E PROMOTORES DE GLICOSILAÇÃO PELO MÉTODO DE KOENIGS-KNORR

We report herein a study on the glycosylation of cyclohexanol with four D-glucosamine-based peracetylated glycosyl chlorides bearing different substituents at C-2 and three glycosylation promoters, silver carbonate, silver triflate and mercury II chloride/mercury II oxide, by the Koenigs-Knorr method. Under the conditions studied, glycosylation was successful only when 3,4,6-tri-O -acetyl-2-deoxy-2-phthalimido-α-D-glucopyranosyl chloride was used as the glycosyl donor, with silver carbonate proving the best promoter. In order to investigate the influence of the nature of the halogen at C-1, we also carried out the glycosylation of cyclohexanol with 3,4,6-tri-O -acetyl-2-deoxy-2-phthalimido-α-D-glucopyranosyl bromide, a more reactive glycosyl donor. As expected, the yield with the bromide derivative was higher with the three promoters and, again, silver carbonate was the most efficient promoter. Finally, to illustrate the well-known efficient procedure for conversion of the phtalimido group at C-2 to the corresponding acetamido group, cyclohexyl 3,4,6-tri-O -acetyl-2-deoxy-2-phtalimido-β-D-glucopyranoside was converted into cyclohexyl 2-deoxy-2-acetamido-β-D-glucopyranoside in two steps, namely, hydrazinolysis of the phtalimido group followed by chemoselective acetylation of the free amino group by treatment with acetic anhydride in methanol, at 77% overall yield.

Synthetic model of a new deoxybenzoin derivative from Deguelia hatschbachii A.M.G. Azevedo

In this paper we describe the synthesis of 2´,4´-dimethoxy-8-(propyl-2-one)-deoxybenzoin, a new compound employed as a model for the comparison with the respective spectral data for 6',4-dihydroxy-3'-(3,3- dimethylallyl)-2",2"-dimethylchromene(5",6":5',4')-2'-methoxy-8-(propyl-2-one) deoxybenzoin, recently isolated from Deguelia hatschbachii A.M.G. Azevedo. Both compounds have a "propyl-2-one" group attached to C-8 of the deoxybenzoin skeleton, for which there is no precedent in the literature. The Friedel-Crafts reaction of 1,3-dimethoxybenzene with phenylacetyl chloride furnished 2´,4´-dimethoxydeoxybenzoin, that after reaction with allyl bromide gave 2´,4´-dimethoxy-8-(allyl)-deoxybenzoin . Wacker oxidation gave the desired model compound in 15% overall yield. The corresponding spectral data reinforced the structure previously determined for the natural product.

Electrochemical evidence of sulfinic acid derivative as an intermediate in the reduction of aromatic sulfonyl chloride in an aprotic medium

The electrochemical reduction of p-nitrobenzenesulfonyl chloride (NBSCl) in dimethylsulfoxide (DMSO) solution is used here as a model to investigate the role of sulfinic acid derivative in this compound's global reduction process. Cyclic voltammetric experiments reveal the production of sulfinic acid derivative, which is important in chemical reactions involving the original compound and other intermediates. This paper also discusses the probable mechanisms of the reduction.

Production of biodiesel from babassu oil using methanol-ethanol blends

Maranhão state in Brazil presents a big potential for the cultivation of several oleaginous species, such as babassu, soybean, castor oil plant, etc... These vegetable oils can be transformed into biodiesel by the transesterification reaction in an alkaline medium, using methanol or ethanol. The biodiesel production from a blend of these alcohols is a way of adding the technical and economical advantages of methanol to the environmental advantages of ethanol. The optimized alcohol blend was observed to be a methanol/ethanol volume ratio of 80 % MeOH: 20 % EtOH. The ester content was of 98.70 %, a value higher than the target of the ANP, 96.5 % (m/m), and the biodiesel mass yield was of 95.32 %. This biodiesel fulfills the specifications of moisture, specific gravity, kinematic viscosity and percentages of free alcohols (methanol plus ethanol) and free glycerin.

Several regulations in gravity table in quality of tobacco seeds

The use of gravity table can result in improved quality of seeds of several species, demonstrating the superiority of the quality attributes of seeds collected in the top positions in relation to the lower positions of the discharge zone of the gravity table. The availability of information on tobacco seeds, particularly on the action of gravity table, has not been addressed in the literature. The present study was to evaluate the influence of different regulations in the gravity table on the quality of tobacco seeds. The terminal edge of the machine of 50 cm width was divided into four parts plus the outlet for stones. The treatments were in the following fractions: original seed (obtained in the feed hopper), heavy seed (at the top), middle high, intermediate, and light seed (lower part), and the stones outlet of the gravity table. Each combination of regulation was in an independent adjustment with a total of seven adjusts. The gravity table, in the adjustments with high oscillation, was efficient in improving the physiological quality of seed lots of tobacco, by removing the fraction of light seeds discharged at the bottom of the terminal edge.

Investment recovery period in electric motor of higher efficiency in pumping for irrigation

In this study, it was adjusted a mathematical model to measure the effect of electric motor efficiency on pumping system costs for irrigation on the tariff structure of conventional electricity and green horo-seasonal , and also to calculate the recovery period of the invested capital in higher efficiency equipment. Then, it was applied to a center pivot irrigation system in two options of electric motor efficiency, 92,6% (standard line) and 94,3% (high efficiency line), and the acquisition cost of the first corresponded to 70% the of the second. The power of the electric motor was 100hp. The results showed that the model allowed us to evaluate if a high efficiency motor was economically viable compared to the standard motor in each tariff structure. The high efficiency motor was not viable in the two tariff structures. In the green horo-seasonal tariff, would only be viable if its efficiency was 4.46% higher than the standard motor. In the conventional tariff, it would only be viable if the efficiency overcame 2.71%.

Association between peripheral arterial disease and creactive protein in the japanese-brazilian population

OBJECTIVE: To evaluate the relationship between peripheral arterial disease and elevated levels of C-reactive protein in the Japanese-Brazilian population of high cardiovascular risk.METHODS: We conducted a cross-sectional study derived from a population-based study on the prevalence of diabetes and associated diseases in the Japanese-Brazilian population. One thousand, three hundred and thirty individuals aged e" 30 underwent clinical and laboratory examination, including measurement of ultrasensitive C-reactive protein. The diagnosis of peripheral arterial disease was performed by calculating the ankle-brachial index. We considered with peripheral arterial disease patients who had ankle-brachial index d" 0.9. After applying the exclusion criteria, 1,038 subjects completed the study.RESULTS: The mean age of the population was 56.8 years; 46% were male. The prevalence of peripheral arterial disease was 21%, with no difference between genders. Data analysis showed no association between peripheral arterial disease and ultrasensitive C-reactive protein. Patients with ankle-brachial index d" 0.70 showed higher values of ultrasensitive C-reactive protein and worse cardiometabolic profile. We found a positive independent association of peripheral arterial disease with hypertension and smoking.CONCLUSION: The association between low levels of ankle-brachial index and elevated levels of ultrasensitive C-reactive protein may suggest a relationship of gravity, aiding in the mapping of high-risk patients.

Contrast sensitivity to angular frequency stimuli is higher than that for sinewave gratings in the respective middle range

This study compares contrast thresholds for sinewave gratings, or spatial frequencies (1/CSF) with contrast thresholds for angular frequencies (1/aCSF) and for radial frequencies, or J0 targets (1/rCSF). Observers had to differentiate between one of these frequency stimuli and a stimulus at mean luminance within a forced-choice procedure. All measurements were made with the same equipment, methods and subjects. Our results show higher sensitivity to, or lower thresholds for, angular frequencies when compared to either sinewave gratings or J0 targets. Contrast values in arbitrary units, in the lower threshold range for angular frequencies, were about half those required to differentiate sinewave gratings from mean luminance in its most sensitive range

Measuring higher order optical aberrations of the human eye: techniques and applications

In the present paper we discuss the development of "wave-front", an instrument for determining the lower and higher optical aberrations of the human eye. We also discuss the advantages that such instrumentation and techniques might bring to the ophthalmology professional of the 21st century. By shining a small light spot on the retina of subjects and observing the light that is reflected back from within the eye, we are able to quantitatively determine the amount of lower order aberrations (astigmatism, myopia, hyperopia) and higher order aberrations (coma, spherical aberration, etc.). We have measured artificial eyes with calibrated ametropia ranging from +5 to -5 D, with and without 2 D astigmatism with axis at 45º and 90º. We used a device known as the Hartmann-Shack (HS) sensor, originally developed for measuring the optical aberrations of optical instruments and general refracting surfaces in astronomical telescopes. The HS sensor sends information to a computer software for decomposition of wave-front aberrations into a set of Zernike polynomials. These polynomials have special mathematical properties and are more suitable in this case than the traditional Seidel polynomials. We have demonstrated that this technique is more precise than conventional autorefraction, with a root mean square error (RMSE) of less than 0.1 µm for a 4-mm diameter pupil. In terms of dioptric power this represents an RMSE error of less than 0.04 D and 5º for the axis. This precision is sufficient for customized corneal ablations, among other applications.

Weight of preterm newborns during the first twelve weeks of life

A longitudinal and prospective study was carried out at two state-operated maternity hospitals in Belo Horizonte during 1996 in order to assess the weight of preterm appropriate-for-gestational-age newborns during the first twelve weeks of life. Two hundred and sixty appropriate-for-gestational-age preterm infants with birth weight <2500 g were evaluated weekly. The infants were divided into groups based on birth weight at 250-g intervals. Using weight means, somatic growth curves were constructed and adjusted to Count's model. Absolute (g/day) and relative (g kg-1 day-1) velocity curves were obtained from a derivative of this model. The growth curve was characterized by weight loss during the 1st week (4-6 days) ranging from 5.9 to 13.3% (the greater the percentage, the lower the birth weight), recovery of birth weight within 17 and 21 days, and increasingly higher rates of weight gain after the 3rd week. These rates were proportional to birth weight when expressed as g/day (the lowest and the highest birth weight neonates gained 15.9 and 30.1 g/day, respectively). However, if expressed as g kg-1 day-1, the rates were inversely proportional to birth weight (during the 3rd week, the lowest and the highest weight newborns gained 18.0 and 11.5 g kg-1 day-1, respectively). During the 12th week the rates were similar for all groups (7.5 to 10.2 g kg-1 day-1). The relative velocity accurately reflects weight gain of preterm infants who are appropriate for gestational age and, in the present study, it was inversely proportional to birth weight, with a peak during the 3rd week of life, and a homogeneous behavior during the 12th week for all weight groups.

Pentoxifylline decreases tumor necrosis factor and interleukin-1 during high tidal volume

Tumor necrosis factor-alpha (TNF-alpha) is one of the most important proinflammatory cytokines which plays a central role in host defense and in the acute inflammatory response related to tissue injury. The major source of TNF-alpha are immune cells such as neutrophils and macrophages. We tested the hypothesis that pentoxifylline, a methylxanthine derivative, down-regulates proinflammatory cytokine expression during acute lung injury in rats. Male Wistar rats weighing 250 to 450 g were anesthetized ip with 50 mg/kg sodium thiopental and randomly divided into three groups: group 1 (N = 7): tidal volume (V T) = 7 ml/kg, respiratory rate (RR) = 50 breaths/min and normal saline infusion; group 2 (N = 7): V T = 42 ml/kg, RR = 9 breaths/min and normal saline infusion; group 3 (N = 7): V T = 42 ml/kg, RR = 9 breaths/min and pentoxifylline infusion. The animals were ventilated with an inspired oxygen fraction of 1.0, a positive end-expiratory pressure of 3 cmH2O, and normal saline or pentoxifylline injected into the left femoral vein. The mRNA of TNF-alpha rapidly increased in the lung tissue within 180 min of ventilation with a higher V T with normal saline infusion. The concentrations of inflammatory mediators were decreased in plasma and bronchoalveolar lavage (BAL) in the presence of higher V T with pentoxifylline infusion (TNF-alpha: plasma, 102.2 ± 90.9 and BAL, 118.2 ± 82.1; IL-1ß: plasma, 45.2 ± 42.7 and BAL, 50.2 ± 34.9, P < 0.05). We conclude that TNF-alpha produced by neutrophil influx may function as an alert signal in host defense to induce production of other inflammatory mediators.

Contrast sensitivity to angular frequency gratings is not higher than to Cartesian gratings

When contrast sensitivity functions to Cartesian and angular gratings were compared in previous studies the peak sensitivity to angular stimuli was reported to be 0.21 log units higher. In experiments carried out to repeat this result, we used the same two-alternative forced-choice paradigm, but improved experimental control and precision by increasing contrast resolution from 8 to 12 bits, increasing the screen refresh rate from 30 Hz interlaced to 85 Hz non-interlaced, linearizing the voltage-luminance relation, modulating luminance in frequencies that minimize pixel aliasing, and improving control of the subject's exposure to the stimuli. The contrast sensitivity functions to Cartesian and angular gratings were similar in form and peak sensitivity (2.4 cycles per visual degree (c/deg) and 32 c/360º, respectively) to those reported in a previous study (3 c/deg and 32 c/360º, respectively), but peak sensitivity to angular stimuli was 0.13 log units lower than that to Cartesian stimuli. When the experiment was repeated, this time simulating the experimental control level used in the previous study, no difference between the peak sensitivity to Cartesian and angular stimuli was found. This result agrees with most current models that assume Cartesian filtering at the first visual processing stage. The discrepancy in the results is explained in part by differences in the degree of experimental control.