Degumming and production of soy lecithin, and the cleaning of a ceramic membrane used in the ultrafiltration and diafiltration of crude soybean oil

The optimization of the cleaning process, aiming to recover the permeate flux, and diafiltration as a means to obtain and purify soybean lecithin, were analyzed in this study as a means of delaying the decrease in permeate flux during the ultrafiltration (UF) of vegetable oils and their derivatives. It also aimed to maximize the exploration of the use of this type of technology during the processing steps. Thus the influence of the transmembrane pressure, cross flow velocity, and the opening of the permeate valve during the cleaning process (hexane circulation) of a ceramic membrane with a permeation area of 0.2 m² and a pore diameter of 0.01 mm in a pilot unit with a processing capacity of 40 L, was studied. Four different operational cleaning conditions, associating combinations of pressure (0.5–2.0 bar) and velocity (1.0–5.0 m s⁻¹), as well as the influence of opening the permeate valve, were studied. Also the production and purification of soybean lecithin was carried out by diafiltration of the retentates derived from the UF of the miscella, resulting in a product with about 90% of acetone insoluble matter. The most favorable cleaning condition was associated with a low pressure (0.5 bar) and elevated velocity (5.0 m s⁻¹), with which it was possible to recover the permeate flux in about 85 min.     

Silver Nanoparticles‐Silsesquioxane Nanomaterial Applied to the Determination of 4‐Nitrophenol as a Biomarker

A novel silsesquioxane material was synthetized and used as a stabilizing agent for silver nanoparticles. This hybrid material was characterized by FTIR, ²⁹Si CP‐MAS NMR, ¹³C DEPT 135° NMR and TGA techniques and the silver nanoparticles were characterized from DLS, UV‐Vis spectroscopy, zeta‐potential, TEM and SAXS results. The silver nanoparticles obtained were spherical in shape with a diameter of 3.74 nm. The nanomaterial was successfully applied in the modification of a glassy carbon electrode and a pronounced current response was obtained in the determination of the biomarker 4‐nitrophenol. Quantum chemical calculations, using density functional theory, were also performed in order to evaluate the redox properties of the analyte. Two different linear ranges were obtained applying optimal square wave voltammetry conditions. The reduction peak currents obtained were linear for 4‐NP concentrations in the ranges of 0.29 to 1.50 μmol L^?1 (E_d=?0.6 V and t_d=20 s) and 2.75 to 31.5 μmol L^?1, with a theoretical (signal to noise=3) limit of detection of 0.05 μmol L^?1 (t_d=20 s). The proposed method was successfully applied to the determination of 4‐NP in synthetic serum samples at different levels of 4‐NP with a recovery range of 94–101 %. Validation was performed using a comparative method through the capillary electrophoresis (CE) technique.     

Action of nitric oxide on healthy and inflamed human dental pulp tissue

Irreversible pulpitis has been associated with pain and an increase in the number of pulp inflammatory cells. Based on the action of nitric oxide (NO) elsewhere, NO may possibly participate in the sensory and autonomic innervation of the dental pulp, and may influence local inflammatory responses. The purpose of this study was to analyze normal and inflamed human dental pulp for the presence of NADPH-diaphorase (NADPH-d), as an index of NO system activity. Six non-carious second premolar pulp tissue samples were obtained from young patients who required extractions for orthodontic reasons and six inflamed samples were obtained from symptomatic carious second premolars clinically diagnosed with irreversible pulpitis. Pulp tissue was carefully removed, fixed by immersion in a cold 4% PFA buffered solution for 120min, rinsed in cold phosphate buffer, and quickly-frozen for cryostat sectioning. Pulp tissue was sectioned perpendicularly to the vertical axis of the tooth at 20mum and processed for histochemistry. Sections of each specimen were stained with hematoxylin-eosin and other sections were subjected to histochemical NADPH-d detection. Results indicated the presence of NADPH reactivity within the pulps of both normal and carious teeth. In the normal teeth NADPH-d activity was detected in a small number of vascular endothelial cells and fibroblasts. The inflammatory response of the pulp from carious premolars was detected in connective tissue by the presence of an increased number of fibroblasts, angioblasts and collagen fibers. It was possible to determine the extent of odontoblast reactivity since the odontoblast layer was usually absent in these split-peel preparations. There were no obvious signs of stained pulpal nerve fibers. Overall NADPH-d staining was significantly more intense within inflamed pulp tissues compared to normal healthy samples (Mann-Whitney test, p<0.002). These results suggest that NADPH-d may be used as a marker of inflammatory activity in pulpitis and provide the basis for further studies aiming to clarify the possible functions of NO in human dental pulp in pathophysiological situations.     

Cytogenetics of four species of Spirostreptidae (Diplopoda, Spirostreptida)

Considering an estimated number of millipedes of approximately 80,000, cytogenetic studies on these animals are rare, as only a total of 70 species have their karyotypes described. The present study reports on the chromosomal number of four Brazilian diplopods of the family Spirostreptidae: Urostreptus atrobrunneus with 2n = 24, XY; Gymnostreptus olivaceus 2n = 12, XY and Alloporus araraquarensis and A. principes, 2n = 18, XY. The C-banding pattern and NOR staining of U. atrobrunneus, G. olivaceus and A. araraquarensis are described.     

Development of low-cost planar electrodes and microfluidic channels for applications in capacitively coupled contactless conductivity detection (C4D)

Electrochemical techniques are commonly applied to micro total analysis system (μTAS) devices mainly due to its high sensitivity and miniaturization capacity. Among many electrochemical techniques, capacitively coupled contactless conductivity detection (C⁴D) stands out for not requiring direct electrode-solution contact, avoiding several problems such as electrolysis, bubble formation, and metal degradation. Furthermore, the instrumentation required for C⁴D measurements is compact, low cost, and easy to use, allowing in situ measurements to be performed even by nonspecialized personal. Contrarily, the production of metallic electrodes and microchannels adequate for C⁴D measurements commonly requires specialized facilities and workers, increasing the costs of applying these methods. We propose alternatives to batch manufacture metallic electrodes and polymeric microchannels for C⁴D analysis using more straightforward equipment and lower-cost materials. Three devices with different dielectric layer compositions and electrode sizes were tested and compared regarding their analytical performance. The constructed platforms have shown a reduction of more than 64% in cost when compared to traditional techniques and displayed good linearity (R² ≥ 0.994), reproducibility (RSD ≤ 4.07%, n = 3), and limits of detection (≤0.26 mmol/L) when measuring standard NaCl samples. Therefore, the proposed methods were successfully validated and are available for further C⁴D applications such as diagnosis of dry-eye syndrome.     

Analysis of synthetic 19-norsteroids trenbolone, tetrahydrogestrinone and gestrinone by gas chromatography-mass spectrometry

Tetrahydrogestrinone, gestrinone and trenbolone are synthetic 19-norsteroids with androgenic properties sharing a labile conjugated ketotrienyl motif. Their LC-MS analyses tend to overcome classical derivatization problems, a shortcoming to the use of GC-MS. Therefore, alternative derivatization procedures were evaluated. The procedure with methoxylamine: pyridine followed by TMSImid: MSTFA gave the best results. This is attributed to the stability of the MO-TMS derivatives hindering the formation of artifacts and tautomerism. A full method is presented including SPE, hydrolysis and liquid-liquid extraction. It was possible to confirm the analytes below 2 ng/mL in urine, being the method robust and cost effective also for screening proposes.     

Analysis of adenosine by RP-HPLC method and its application to the study of adenosine kinase kinetics

An RP-HPLC method for the analysis of adenosine (ADO) has been developed and validated. In the present study, we report an RP-HPLC-based method with modifications of mobile phase and shorter retention time that substantially improved the efficiency of ADO analysis. The HPLC separation of the ADO was achieved on a C18 column, using a mobile phase consisting of water, containing 7% v/v ACN, at a flow rate of 0.8 mL/min. The column effluent was monitored by UV detection at 260 nm. A linear response was achieved over the concentration range of 0.25-100.00 micromol/L. The analytical method inter- and intra-run accuracy and precision were better than +/- 15%. The LOQ was 0.25 micromol/L, with ADO detection in the range of 6.25 pmol per sample. The method has been applied to the study of adenosine kinase (AK) kinetics.     

Toxicological Stability of Ocimum basilicum Essential Oil and Its Major Components in the Control of Sitophilus zeamais

Essential oils (EOs) are widely recognized as efficient and safe alternatives for controlling pest insects in foods. However, there is a lack of studies evaluating the toxicological stability of botanical insecticides in stored grains in order to establish criteria of use and ensure your efficiency. The objective of this work was to evaluate the toxicological stability of basil essential oil (O. basilicum) and its linalool and estragole components for Sitophilus zeamais (Motschulsky) adults in corn grains by fumigation. The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass selective detector. Mortality of insects was assessed after 24 h exposure. After storage for six (EO) and two months (linalool and estragole) under different conditions of temperature (5, 20, and 35 °C) and light (with and without exposure to light), its toxicological stability was evaluated. Studies revealed that the essential oil of O. basilicum and its main components exhibited insecticidal potential against adults of S. zeamais. For greater toxicological stability, suitable storage conditions for them include absence of light and temperatures equal to or less than 20 °C.     

Optimization and validation of an SBSE–HPLC–FD method using laboratory‐made stir bars for fluoxetine determination in human plasma

Depression is the largest cause of disability worldwide, affecting 350 million people. Notwithstanding that clinical trials demonstrate antidepressants efficacy, the efficient response can vary individually concerning therapeutic dosage. Although important, plasma levels monitoring remains an analytical challenge whereas clean‐up and pre‐concentration represent critical steps. Therefore, this study aims to develop, optimize and validate a method for fluoxetine determination in human plasma, employing a laboratory‐made device consisting of a PDMS stir bar sorptive for extraction, coupled with high‐performance liquid chromatography–fluorescence detection (SBSE–HPLC–FD). Optimization involved sorption–desorption steps. For sorption, temperature and time were assessed by factorial and central composite design approaches, taking into account the desirability and the response surface results, with stirring speed also examined. For desorption kinetics and ultrasonic and magnetic stirring mode were evaluated. The proposed method after validation was robust, linear (25.00–1000.00 ng mL^?1, R² > 0.98) and presented good intra‐ (RSD 4.18%) and inter‐day‐assay (RSD 11.60%) precision and accuracy (recovery 109.60%), allowing reliable quantitation without interference. The method was successfully applied to real samples. SBSE–HPLC–FD could represent a feasible alternative with good cost–benefit for low‐volume samples and therapeutic drug monitoring, as well as contributing to correlation studies between plasma fluoxetine levels and clinical response, which is still little studied.