P. B. A. Fechine

Evaluation of a low-cost adsorbent for removal of toxic metal ions from wastewater of an electroplating factory.

In this study, sugar cane residue or bagasse was used for removal of toxic metal ions from wastewater of an electroplating factory located in northeast Brazil. Prior acid treatment increased the adsorption efficacies in batch wise experiments. The microstructure of the material before and after the treatment was investigated by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Column operations showed that removals of Cu(2+), Ni(2+) and Zn(2+) from wastewater (in the absence of cyanide) were 95.5%, 96.3.0%, and 97.1%, respectively. Regeneration of the adsorbent obtained in acid indicated that the efficiencies decreased only after the fourth cycle of re-use. Acid-treated sugar cane bagasse can be considered a viable alternative to common methods to remove toxic metal ions from aqueous effluents of electroplating industries.

Adsorption of polycyclic aromatic hydrocarbons from aqueous solutions by modified periodic mesoporous organosilica

A novel procedure was developed for the synthesis of a periodic mesoporous organosilica (PMO), which was used to remove polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. Adsorption equilibrium isotherms and adsorption kinetics experiments were carried out in solutions of PAHs (2-60 mg L(-1)), using the PMO as adsorbent. Adsorption models were used to predict the mechanisms involved. The adsorption kinetics data best fitted the pseudo-first-order kinetic model for naphthalene, and to the pseudo-second-order model for fluorene, fluoranthene, pyrene, and acenaphtene. The intraparticle model was also tested and pointed to the occurrence of such processes in all cases. The isotherm models which best represented the data obtained were the Freundlich model for fluoranthene, pyrene, and fluorene, the Temkin model for naphthalene, and the Redlich-Peterson model for acenaphtene. PAHs showed similar behavior regarding kinetics after 24 h of contact between adsorbent and PAHs. FTIR, XRD, BET, and SEM techniques were used for the characterization of the adsorbent material.

Dielectric permittivity and loss of CaCu3Ti4O12 (CCTO) substrates for microwave devices and antennas

The solid state procedure was used to produce bulk ceramics of CCTO (CaCu3Ti4O12). The samples of the CCTO ceramic were studied by X-ray powder diffraction, infrared and Raman scattering spectroscopy. The infrared and Raman scattering spectroscopy confirm the formation of the CCTO phase as seen by X-ray diffraction analysis. For one experimental procedure one uses an organic binder in the process of shaping the samples. In the second procedure the samples were prepared without the presence of the organic phase. For the second situation, we had higher dielectric constant (ɛr=7370) with high loss (D=0.2) at 1 KHz. For the first procedure one has the lower dielectric constant (ɛr=1530) and lower loss (D=0.11) at 1 KHz. Simple rectangular antenna prototypes were also designed on substrate samples (C1, C2, P1 and P2). For the antennas (with P2, C1 and C2 as substrates), the bandwidth (BW) is 90 MHz (around 3%). The antenna with P1 substrate presented a surprisingly high BW of 270 MHz that corresponds to a 10% bandwidth. In the microwave range one observes that higher values of the ɛr in the range of 3 GHz antennas is also presented by the P1 sample (ɛr=41.6), and the lowest one was presented by P2 (ɛr=33.7). Sample P1 also presents the highest value for the loss (Q−1) which is around 0.1 compared to the other samples which is around 0.03. Therefore, these measurements confirm the potential use for small high dielectric planar antennas. These materials are also attractive for capacitor applications and certainly for microelectronics, and microwave devices (e.g., cell mobile phones), where the miniaturization of the devices is crucial.

ANTIFUNGAL ACTIVITY OF SILVER NANOPARTICLES OBTAINED BY GREEN SYNTHESIS

Silver nanoparticles (AgNPs) are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS) as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD) in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment.

Yttrium Iron Garnet: Properties and Applications Review

Due to a fast progress in the development of communication systems, the dielectric and magnetic ceramics (ferrites) have become attractive to be used in devices. Although the ferrites of the spinel type were the first material to be used in the microwave range, garnets have smaller dielectric losses and, therefore, are chosen for many applications. High demands for modern electric applications in magnetic materials results in new techniques and products being permanently studied and researched, with a consequent appearance of new solutions for a wide applications series. This work presents the study of the ferrimagnetic composite, constituted by Y3Fe5O12 (YIG) and Gd3Fe5O12 (GdIG) phases, through solid state synthetic route and submitted to high-energy mechanical milling. Additionally, experiments were made in order to evaluate the electric and magnetic behavior of the composites at radio frequency and microwave range and then later suggest an adequate technological application. The composites were efficient as ferrite resonator antennas (FRAs) and microstrip antennas (thick films deposited on metalized surface alumina substrate by screen-printing technique), in the microwave frequency range. The experiments with FRAs showed satisfactory results due to the control of the antennas radiation characteristics and their tuning by the use of an external magnetic field. The composite resonators studied in this work can be important to the development of a third generation (3G) wideband antennas to cell phones and other wireless products.

Fast ultrasound assisted synthesis of chitosan-based magnetite nanocomposites as a modified electrode sensor.

Chitosan-based magnetite nanocomposites were synthesized using a versatile ultrasound assisted in situ method involving one quick step. This synthetic route approach results in the formation of spheroidal nanoparticles (Fe3O4) with average diameter between 10 and 24nm, which were found to be superparamagnetic with saturation magnetization (Ms) ranges from 32-57emug(-1), depending on the concentration. The incorporation of Fe3O4 into chitosan matrix was also confirmed by FTIR and TG techniques. This hybrid nanocomposite has the potential application as electrochemical sensors, since the electrochemical signal was excepitionally stable. In addition, the in situ strategy proposed in this work allowed us to synthesize the nanocomposite system in a short time, around 2min of time-consuming, showing great potential to replace convencional methods. Herein, the procedure will permit a further diversity of applications into nanocomposite materials engineering.

Nanostructured transdermal hormone replacement therapy for relieving menopausal symptoms: a confocal Raman spectroscopy study

OBJECTIVE: To determine the safety and efficacy of a transdermal nanostructured formulation of progesterone (10%) combined with estriol (0.1%) + estradiol (0.25%) for relieving postmenopausal symptoms. METHODS: A total of 66 postmenopausal Brazilian women with climacteric symptoms of natural menopause received transdermal nanostructured formulations of progesterone and estrogens in the forearm daily for 60 months to mimic the normal ovarian secretory pattern. Confocal Raman spectroscopy of hormones in skin layers was performed. Clinical parameters, serum concentrations of estradiol and follicle-stimulating hormone, blood pressure, BI-RADS classification from bilateral mammography, and symptomatic relief were compared between baseline and 60 months post-treatment. Clinicaltrials.gov: NCT02033512. RESULTS: An improvement in climacteric symptoms was reported in 92.5% of women evaluated before and after 60 months of treatment. The serum concentrations of estradiol and follicle-stimulating hormone changed significantly (p<0.05) after treatment; the values of serum follicle-stimulating hormone decreased after 60 months from 82.04±4.9 to 57.12±4.1 IU/mL. A bilateral mammography assessment of the breasts revealed normal results in all women. No adverse health-related events were attributed to this hormone replacement therapy protocol. CONCLUSION: The nanostructured formulation is safe and effective in re-establishing optimal serum levels of estradiol and follicle-stimulating hormone and relieving the symptoms of menopause. This transdermal hormone replacement therapy may alleviate climacteric symptoms in postmenopausal women.

Magnetic Nanosystem for Cancer Therapy Using Oncocalyxone A, an Antitomour Secondary Metabolite Isolated from a Brazilian Plant

This paper describes the investigation and development of a novel magnetic drug delivery nanosystem (labeled as MO-20) for cancer therapy. The drug employed was oncocalyxone A (onco A), which was isolated from Auxemma oncocalyx, an endemic Brazilian plant. It has a series of pharmacological properties: antioxidant, cytotoxic, analgesic, anti-inflammatory, antitumor and antiplatelet. Onco A was associated with magnetite nanoparticles in order to obtain magnetic properties. The components of MO-20 were characterized by XRD, FTIR, TGA, TEM and Magnetization curves. The MO-20 presented a size of about 30 nm and globular morphology. In addition, drug releasing experiments were performed, where it was observed the presence of the anomalous transport. The results found in this work showed the potential of onco A for future applications of the MO-20 as a new magnetic drug release nanosystem for cancer treatment.

Dielectric investigation of the Sr3WO6 double perovskite at RF/microwave frequencies

This work reports the dielectric properties of Sr3WO6 (SWO) double perovskite at radio frequencies as a function of the temperature and a study in microwaves range to evaluate the material as a novel dielectric resonator. Thermo-activated charge transfer process for SWO ceramic was observed and two resistor–capacitor associations were fitted for the Nyquist diagram. SWO presented negative values of temperature coefficient of capacitance (TCC) and the activation energies of dielectric relaxation processes were measured by conductivity (1.35 eV), imaginary modulus (1.38 eV) and imaginary impedance (1.36 eV). For the microwave range, SWO shows high dielectric permittivity (13.57) and dielectric loss (0.0281). The dielectric resonator antenna (DRA) fabricated from SWO ceramic presented an operation frequency in 4.1 GHz and return loss below −40 dB. It was possible to evaluate the performance of the antenna from numerical simulation. From these results, the SWO based DRA shows good properties to be used as a novel microwave dielectric resonator.

Determination of Insecticide Residues in Vegetal Fruits

Pesticides compounds represent an important class of pollutants for food, soil and surface water resources. Thus, a simplified method using gas chromatography was used for determining five insecticide residues in fruit samples produced in Ceara State (Brazil). The insecticides were simultaneously extracted from the fruit samples with a mixture of water-methanol (1 : 1% v/v) from lipid-containing crops and then reextracted with ethyl acetate. Cleanup by silica gel column chromatography was not necessary. The extracts were analyzed by GC-ECD. Analytical parameters, such as limit of detection (LOD), limit of quantification (LOQ), linearity, precision, and recovery were considered for the orange fruit. A sufficient recovery of 52.1, 57.0, 49.5, and 108.5% for parathion methyl, malathion, chlorpyrifos, and 2,4-dichlorophenol was found. The compounds 2,4-dichlorophenol, malathion, parathion methyl, and chlorpyrifos were found in all the fruit samples analyzed.