Application of selective solid-phase extraction using a new core-shell-shell magnetic ion-imprinted polymer for the analysis of ultra-trace mercury in serum of gallstone patients

ABSTRACT

A new ultrasonically assisted spectrophotometric method was developed using stabilized ion polymer on a modified nano-absorbent as a core- shell-shell absorbent (Fe₃O₄@SiO₂@TiO₂–IIP). It has the advantages of further stabilizing the polymer and consequently and much higher efficiency than its conventional adsorbents. The prepared sorbent was characterized and Its parameters were investigated by a Box–Behnken design. The linear dynamic range and limit of detection were 0.20–28.00 µg L^?1 and 0.05 µg L^?1 respectively. In selectivity study, it was founded that imprinting causes increased affinity of the prepared IIP toward Hg²⁺ ion. The proposed IIP is considered to be promising and selective sorbent for solid-phase extraction and preconcentration of Hg²⁺ ion in sera of different types of gallstone patients.     

Characterization of Al18B4O33 ceramic synthesized by the sol-gel,precipitation, and combustion methods

In this study, Al₁₈B₄O₃₃ aluminum borate is synthesized by the sol-gel, precipitation, and combustion methods, which use similar starting materials. Simultaneous thermal analyzer and Fourier transform infrared spectroscopy are employed to determine the thermal behavior and the chemical bonding structures. In addition, the crystal structure and microstructure are identified by X-ray diffraction and scanning electron microscope. The results reveal that Al₁₈B₄O₃₃ nanorods are produced by sol-gel method and citric acid controls the morphology of powders. Additionally, Al₁₈B₄O₃₃ phase is obtained by decomposing Al₄B₂O₉ unstable phase at 1000°C by sol-gel method. However, Al₁₈B₄O₃₃ phase is immediately obtained from calcination of an amorphous phase at 1000°C by precipitation and combustion methods.     

Analysis of Nonlinearities in Superconducting Microstrip Straight Bends; FDTD Method in Comparison with Nonlinear Circuit Modeling

This paper presents the prediction of nonlinearities in the superconducting microstrip straight bends in microwave frequencies based on two different methods; FDTD simulation as a numerical approach, and nonlinear circuit modeling as an analytical method. In the FDTD method, the superconducting microstrip structures are simulated with London’s equations. In the simulation, the penetration depth and normal conducting coefficient are considered as functions of current density of superconductor. To simulate the thin strip of superconductor, a non-uniform mesh has been used. For the nonlinear circuit modeling, we use distributed RLGC parameters for superconducting microstrip transmission lines. These parameters are considered as functions of the current distribution. This yields an equivalent nonlinear circuit model for bends. The final equivalent nonlinear circuit is analyzed using the harmonic balance (HB) method. Different straight bend structures have been considered and the two methods’ results are compared.     

Improving the tracking and erosion resistance of silicone rubber using Fe2O3 and platinum catalyst

In typical HTV silicone rubber for composite insulators subjected to a 4.5 kV inclined plane (IP) test, alumina trihydrate loading exceeds 40 wt%, which limits the rubber content and weakens the antiaging properties. This study compares two methods for enhancing tracking and erosion resistance while reducing ATH content to meet IP test requirements. Increasing Fe₂O₃ content from 1.5 wt% to 3 wt% promotes the formation of mullite. The formed ceramic layer isolates heat and oxygen and hence facilitates the specimen to pass the IP tests with less content of ATH. By contrast, Pt/NS system cannot suppress the tracking efficiently by forming the Si O C ceramics at high ATH loading. The decomposition of ATH will generate water vapor and lead to holes in the surface. Both moisture and oxygen absorbed have a detrimental effect on the suppression mechanism of the Pt/NS system. Consequently, it is recommended that the content of Fe₂O₃ can be increased slightly to lower the ATH content in the traditional HTV SiR formula used for the composite insulator. Besides, when the content of ATH is relatively high, the use of the Pt/NS system is not recommended.     

Highly resistant icephobic coatings on aluminum alloys

Aluminum alloys are widely used for outdoor structures such as ground wires and phase conductors of overhead power lines, as well as aircrafts wings and fuselage. To protect these surfaces against excessive ice accumulation, icephobic coatings must be highly reliable and durable. New coatings with icephobic characteristics and excellent mechanical properties have been developed. The method consisted in depositing an extremely adherent poly(tetrafluoroethylene) (PTFE) coating on an Al₂O₃ underlayer produced by anodizing in a phosphoric acid electrolyte followed by an oxide etching step to enhance surface roughness. PTFE impregnation was carried out at low temperature (320 °C) and coating adhesion was assessed using tape and bend tests. Some of these coatings showed superhydrophobic properties; ice adhesion was around four times lower than bare aluminum. As well, they remained effective after ten ice-shedding events using an aggressive centrifugal technique. Moreover, no sign of PTFE degradation after 14 ice removals was noted and the coatings remained extremely adherent and very hydrophobic. This technique therefore shows very good potential and could be applied to new high-voltage overhead aluminum cables as protection against excessive ice or snow accumulation.     

Impact of fruit processing methods on DNA extraction from transgenic frozen banana products

Isolation of high yield and quality of genomic DNA is paramount for ensuring confidence in molecular analyzing food. This study evaluated five different DNA extraction procedures based on laboratory protocols and commercial kits for their efficiency and also assessed the impact of processing procedures on the DNA degradation in various frozen banana products such as frozen-sliced banana, frozen banana puree, frozen plantain banana, and freeze-dried banana powder. The purity and concentration of DNA obtained from the samples were evaluated by spectrophotometric and gel electrophoresis analysis. Of the various extraction procedures, we applied modified protocols that allow for effective extraction of DNA from banana. This protocol derived from traditional cetyltrimethylammonium bromide method with modifications that allowed removing unwanted polyphenols and polysaccharides. The results confirm that a profound impact on DNA degradation was seen during the processing of banana products, DNA could still be reliably quantified by real-time PCR. Furthermore, frying resulted in further degradations and drying resulted in the most severe changes. It was noted that in different frozen banana products, nopaline synthase fragment is most stable followed by cauliflower mosaic virus 35S and NPTII gene.     

Screening of the Antioxidant and Enzyme Inhibition Potentials of Portuguese <Emphasis Type="Italic">Pimpinella anisum</Emphasis> L. Seeds by GC-MS

The results of GC-MS analysis are used to characterise the bioactive compounds in the infusion. The obtained results of the current research clearly revealed that the phenols, flavonoids and monomeric anthocyanins are abundant and a high-antioxidant activity of Pimpinella anisum L. infusions was detected. As expected, the studied plant’s infusion showed a stronger activity against free radicals than the enzymes that are attributed to generation of various chronic diseases. Among the characterised compounds, the fatty acids were detected with the highest quantity with 47.68% followed by triterpenoids and sterols, with 15.56 and 7.29%, respectively. Fatty acids (linoleic, oleic and palmitic acids), triterpenoids (lupeol, β-Amyrin and betulinic acids (BAs)) as well as sterols (β-sitosterol and stigmasterol) were detected as the main bioactive compounds in the studied infusion. In the current research, these compounds were detected to have substantial impacts on revealing of the potential health benefits of P. anisum L. seeds.     

Cloud point preconcentration and flame atomic absorption spectrometry: application to the determination of manganese in milk and water samples

Cloud point extraction has been used for preconcentration of trace amount of manganese. The analyte was complexed with 1-(2-pyridylazo)-2-naphtol (PAN) and Triton X-114 was added as surfactant. After phase separation, based on the cloud point of the mixture, and dilution of the surfactant-rich phase with methanol, the enriched analyte was determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, enhancement factor of 49.1 was obtained. The detection limit was 0.39 ng ml⁻¹ for manganese. The proposed method was applied to the determination of manganese in milk and water samples.     

Analysis of antibiotic resistance patterns and detection of mecA gene in Staphylococcus aureus isolated from packaged hamburger

Presence of Staphylococcus aureus, antibiotic resistance pattern and PCR detection of mecA gene in isolated strains were investigated in total of 256 packaged hamburgers in Iran-Tehran. For this purpose we used standard disk-diffusion method and sensitive and specific PCR technique, respectively. Results showed that 25% of samples were positive for S. aureus. Resistance to meticillin, erythromycin, penicillin G, cefazolin, ciprofloxasin, vacomycin and amoxiclave was determined 89%, 20.3%, 18.7%, 15.6%, 14%, 26.6% and 12.5%, respectively. According to the obtained results from PCR analysis of methicillin-resistant S. aureus (MRSA), mecA gene was present in 100% of the resistant isolates, 0% of intermediate-resistance isolates and 25% of susceptible isolates. The results obtained from PCR detection of mecA gene showed high correlation with standard disk diffusion test.