A cellulose monolithic stir bar for sorptive extraction of glycerol from biodiesel.

This work presents an eco-friendly approach for determining free glycerol in biodiesel samples, using a cellulose monolith stir bar in the sorptive extraction method with analysis by high-performance liquid chromatography and a refractive index detector. The cellulose monolith was produced from cellulose acetate by non-solvent-induced phase separation and subsequent alkaline deacetylation. The cellulose monolith presented a hierarchically porous structure, with 68% porosity and almost total deacetylation, with morphological and polarity characteristics that favor an efficient extraction of free glycerol from biodiesel. The sorptive extraction method using a cellulose monolith stir bar was optimized, obtaining a total extraction time of 30 min at 70 °C, using ultrapure water as the desorption solvent, and extraction of free glycerol of 93.6 ± 2.3%. The proposed method showed selectivity in free glycerol extraction, with limits of detection and quantification of 6.60 × 10-5% w/w and 2.18 × 10-4% w/w, respectively. Compared with the official reference method, the proposed one presented similar precision and accuracy, with few manipulations and any reagent/solvents. Furthermore, it is compatible with the principles of green chemistry and can be considered an eco-friendly method for determining free glycerol in biodiesel.

Improved L-Asparaginase Properties and Reusability by Immobilization onto Functionalized Carbon Xerogels.

Enzyme immobilization can offer a range of significant advantages, including reusability, and increased selectivity, stability, and activity. In this work, a central composite design (CCD) of experiments and response surface methodology (RSM) were used to study, for the first time, the L-asparaginase (ASNase) immobilization onto functionalized carbon xerogels (CXs). The best results were achieved using CXs obtained by hydrothermal oxidation with nitric acid and subsequent heat treatment in a nitrogen flow at 600 °C (CX-OX-600). Under the optimal conditions (81 min of contact time, pH 6.2 and 0.36 g/L of ASNase), an immobilization yield (IY) of 100 % and relative recovered activity (RRA) of 103 % were achieved. The kinetic parameters obtained also indicate a 1.25-fold increase in the affinity of ASNase towards the substrate after immobilization. Moreover, the immobilized enzyme retained 97 % of its initial activity after 6 consecutive reaction cycles. All these outcomes confirm the promising properties of functionalized CXs as support for ASNase, bringing new insights into the development of an efficient and stable immobilization platform for use in the pharmaceutical industry, food industry, and biosensors.

Sociodemographic and obstetric factors associated with health-related quality of life of high-risk pregnant women.

OBJECTIVE: To evaluate the association between sociodemographic and obstetric factors and the health-related quality of life of pregnant women in high-risk prenatal care. METHODS: A cross-sectional study of women in high-risk prenatal care in Ceara, Brazil. The investigated outcomes were health-related quality of life, using the Medical Outcomes Study 36-item short-form health survey; the investigated covariates were sociodemographic and obstetric data. Associative analyses were performed using the Jamovi® software version 0.9. RESULTS: Of the 276 women included in the study, women with the following characteristics presented a better quality of life in some domain of the scale: age equal to or greater than 35 years, higher income per dependent, religious, living with three or fewer persons, with their own home, in primigestation, nulliparous, with no history of previous abortion, and with up to two living children. The regression model showed an association between the total scale score, which means a higher quality of life in women with age equal to or greater than 35 years and a higher income per dependent. CONCLUSION: The study identified sociodemographic and obstetric factors that may affect the quality of life of high-risk pregnant women, providing subsidies to health providers so that they can promote better prenatal care.

Multi-component adsorption study by using bone char: modelling and removal mechanisms.

Highly efficient simultaneous removal of paracetamol and Cu2+ ions from aqueous solutions was accomplished by using bovine bone char (BC). The adsorption behaviour was determined by kinetic and equilibrium studies of both single and binary system solutions. BC is a predominantly mesoporous material with a surface area of 103 m2 g-1. The influence of the initial pH on Cu2+ removal was tested, suggesting that the optimal pH was 3.0. The removal of paracetamol from single and binary systems was 9.45 and 12.7%, respectively. On the other hand, the Cu2+ removal was 36.2% for a single system, suggesting a higher affinity for BC. Moreover, in the case of binary mixtures, the presence of paracetamol led to an enhanced affinity of Cu2+ due to a synergistic/cooperative mechanism, which led to a copper removal of 97.3%. The cooperative model was successfully adjusted to the equilibrium data of the binary systems. The modelling results indicated the formation of a first adsorption layer where paracetamol and copper are retained, and a second layer with a great affinity for copper ions after the formation of a Cu-paracetamol complex, leading to higher removal of Cu2+.

Superior operational stability of immobilized L-asparaginase over surface-modified carbon nanotubes.

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes the L-asparagine hydrolysis into L-aspartic acid and ammonia, being mainly applied in pharmaceutical and food industries. However, some disadvantages are associated with its free form, such as the ASNase short half-life, which may be overcome by enzyme immobilization. In this work, the immobilization of ASNase by adsorption over pristine and modified multi-walled carbon nanotubes (MWCNTs) was investigated, the latter corresponding to functionalized MWCNTs through a hydrothermal oxidation treatment. Different operating conditions, including pH, contact time and ASNase/MWCNT mass ratio, as well as the operational stability of the immobilized ASNase, were evaluated. For comparison purposes, data regarding the ASNase immobilization with pristine MWCNT was detailed. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95% under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5 × 10-3 g mL-1 of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), paving the way for its use in industrial processes.

Development and characterization of a novel l-asparaginase/MWCNT nanobioconjugate.

The enzyme l-asparaginase (ASNase) presents effective antineoplastic properties used for acute lymphoblastic leukemia treatment besides their potential use in the food sector to decrease the acrylamide formation. Considering their applications, the improvement of this enzyme's properties by efficient immobilization techniques is in high demand. Carbon nanotubes are promising enzyme immobilization supports, since these materials have increased surface area and effective capacity for enzyme loading. Accordingly, in this study, multi-walled carbon nanotubes (MWCNTs) were explored as novel supports for ASNase immobilization by a simple adsorption method. The effect of pH and contact time of immobilization, as well as the ASNase to nanoparticles mass ratio, were optimized according to the enzyme immobilization yield and relative recovered activity. The enzyme-MWCNTs bioconjugation was confirmed by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman and transmission electron microscopy (TEM) studies. MWCNTs have a high ASNase loading capacity, with a maximum immobilization yield of 90%. The adsorbed ASNase retains 90% of the initial enzyme activity at the optimized conditions (pH 8.0, 60 min, and 1.5 × 10-3 g mL-1 of ASNase). According to these results, ASNase immobilized onto MWCNTs can find improved applications in several areas, namely biosensors, medicine and food industry.

A comparative study for the ion exchange of Fe(III) and Zn(II) on zeolite NaY.

The uptake capacity of Fe(III) and Zn(II) ions in NaY zeolite was investigated. Experiments were carried out in a fixed bed column at 30 degrees C, pH 3.5 and 4.5 for Fe(III) and Zn(II), respectively, and an average particle size of 0.180 mm. In order to minimize the diffusional resistances the influence of flow rate on the breakthrough curves at feed concentrations of 1.56 meq/L for Fe(III) and 0.844 meq/L for Zn(II) was investigated. Flow rate of the minimal resistance in the bed according to mass transfer parameter were 2.0 mL/min for iron and 8.0 mL/min for zinc ions. Freundlich and Langmuir isotherm models have been used to represent the column equilibrium data. The iron dynamic isotherm was successfully modeled by the Langmuir equation and this mathematical model described well the experimental breakthrough curves for feed concentrations from 0.1 up to 3.5 meq/L. The zinc dynamic isotherm was successfully modeled by the Freundlich equation. This equilibrium model was applied to mathematical model. Experimental breakthrough curves could be predicted. Experiments were also carried out in a batch reactor to investigate the kinetics adsorption of the ions Fe(III) and Zn(II). Langmuir kinetic model fit well both experimental data.

Combined radioguided nonpalpable lesion localization and sentinel lymph node biopsy for early breast carcinoma.

BACKGROUND: The aim of this study was to test a new strategy for radioguided management of malignant or suspicious nonpalpable breast lesions, with a combination of radioguided occult lesion localization (ROLL), sentinel lymph node (SLN) mapping, and, if necessary, immediate local surgery and SLN biopsy with a single injection of (99m)Tc-labeled dextran for the whole procedure. METHODS: A total of 115 nonpalpable lesions were studied: 101 with high suspicion of malignancy from which frozen sections had been produced, and 14 carcinomas diagnosed by mammotomy. On the day before surgery, 0.2 mL of solution of dextran labeled with 15 MBq of (99m)Tc was injected into the center of the lesions under imaging guidance. All patients underwent lymphoscintigraphy and open-surgery biopsy guided by gamma probe, followed by radiographic verification of the specimen. If malignancy was detected, in cases of infiltrating or ductal carcinoma-in-situ with comedonecrosis or high nuclear grade, breast-conserving surgery and SLN biopsy were performed during the same operation. RESULTS: The combination of ROLL and SLN biopsy was feasible and practical. The rate of simultaneous SLN mapping by lymphoscintigraphy was 97.4% (112 of 115), and the confirmation rate for breast lesion removal by specimen radiography was 100%. It was known that 57 cases were malignant at the time of surgery. After segmental breast resection, SLN immediately underwent biopsy in 50 cases (34 infiltrating carcinomas and 16 ductal carcinoma-in-situ) with probe monitoring. Three were cytologically positive for metastasis and required full axillary dissection. CONCLUSIONS: ROLL and SLN biopsy are emerging procedures that can be used simultaneously. They permit exact breast lesion excision, immediate local breast surgery, and intraoperative SLN biopsy in a single procedure. The combination of radioguided nonpalpable lesion localization and SLN biopsy is a suitable alternative to working up subclinical imaging-detected breast carcinomas.

Tiroidite crônica na infância e adolescência / Chronic thyroiditis in the childhood and adolescence

Sao apresentadas as alteraçoes clínicas e laboratoriais em um grupo de 15 pacientes portadores de tiroidite crônica autoimune na faixa etária de 8 a 17 anos. Correlaciona-se tais alteraçoes com achados da citologia obtidos por Punçao Aspirativa com Agulha Fina (PAAF). Os pacientes foram divididos em 3 grupos de acordo com as concentraçoes de TSH e T4: grupo I (n=5) com T4 e TSH séricos dentro dos limites da normalidade, grupo II (n=4) com T4 normal e TSH elevado e grupo III (n=6) com T4 diminuído e TSH elevado. Neste último grupo 5 pacientes apresentaram também T3 sérico diminuído. Todos os pacientes apresentaram títulos positivos de anticorpos antimicrossomais (ACAM) em pelo menos uma avaliaçao. O estudo citológico revelou tiroidite crônica em todos os grupos estudados. Nao se observou correlaçao entre os níveis de TSH e títulos de ACAM. O emprego da PAAF na pesquisa etiológica de bócio em crianças e adolescentes, mostrou-se confiável, de grande acuidade e utilidade diagnóstica.