Designing and fabrication of a novel gold nanocomposite structure: application in electrochemical sensing of bisphenol A

In this article, a highly sensitive electrochemical sensor is introduced for direct electro-oxidation of bisphenol A (BPA). The novel nanocomposite was prepared based on multi-walled carbon nanotube/thiol functionalised magnetic nanoparticles (Fe₃O₄-SH) as an immobilisation platform and gold nanoparticles (AuNPs) as an amplifying electrochemical signal. The chemisorbed AuNPs exhibited excellent electrochemical activity for the detection of BPA. Some analysing techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy-dispersive x-ray diffraction exposed the formation of nanocomposite. Under optimum conditions (pH 9), the sensor showed a linear range between 0.002–240 μM, with high sensitivity (0.25 μA μM^?1) along with low detection limit (6.73 × 10^?10 M). Moreover, nanocomposites could efficiently decrease the effect of interfering agents and remarkably enhance the utility of sensor at detection of BPA in some real samples.     

Electromyography Activity of Vastus Medialis Obliquus and Vastus Lateralis Muscles During Lower Limb Proprioceptive Neuromuscular Facilitation Patterns in Individuals with and without Patellofemoral Pain Syndrome

Objective: Exercise therapy to strengthen quadriceps muscle is recommended in rehabilitation program for people with patellofemoral pain syndrome (PFPS). This study aimed to investigate the electromyography (EMG) activity of vastus medialis obliquus (VMO), vastus lateralis (VL) and VMO/VL ratio during PNF in individuals with and without PFPS. Methods: 26 persons with PFPS and 26 healthy subjects participated to study. All subjects performed PNF patterns (Flexion-Adduction-External Rotation (D₁FL), Extension-Adduction-External Rotation (D₂EX), D₁FL+ load, D₂EX+ load) and straight leg raise (SLR). The normalized EMG activity of VMO, VL and VMO/VL ratio were measured and analyzed using repeated measure ANOVA. Results: There were significant main effects of group and exercises for the both VMO and VL (p<0.05). It was found that except SLR and D₂EX, in the other motions PFPS group had lower VMO activity compared to healthy group (p<0.05). For VL except SLR, in the other motions PFPS group had lower VL activity too (p<0.05). The PNF patterns activated VMO more than SLR, however it was not significant (p>0.05). Also; there weren''t any significant difference between the two groups in VMO/VL activation ratios. Also, performing the PNF patterns with load increased VMO and VL muscles activity significantly (p<0.05). It also found that in PFPS group the VMO/VL ratio values in PNF patterns were significantly more than SLR and the highest VMO/VL ratio value (0.96) was found during D₂EX. Conclusion: The PNF patterns due to provide optimal VMO/VL ratio value than SLR and proper balance between these two muscles can be recommended in rehabilitation of individuals with PFPS.     

MgO纳米晶负载镍催化剂用于甲烷蒸汽重整反应(英文)

Nanocrystalline MgO with a relatively high surface area and mesoporous structure was synthesized by a surfactant assisted precipitation method for use as the support of nickel catalysts for steam reforming of methane. The samples were characterized by X‐ray diffraction, N2 adsorption, temperature‐programmed reduction, temperature‐programmed oxidation, scanning electron microscopy, and transmission electron microscopy. The catalysts showed high catalytic activity and good stability in the steam reforming of methane. Increasing the nickel loading up to 10 wt% gave increased activity. Catalysts with higher nickel loadings showed more deposited carbon after reaction. The excellent anti‐coking performance of the catalysts was attributed to the formation of a nickel‐magnesia solid solution, basicity of the support surface, and nickel‐support interaction.     

Purification assay to prepared ultrapure carboxymethyl-chitosan

Carboxymethyl Chitosan (CMCh) is a semi-synthetic derivative of chitosan (a natural biopolymer) with increasing biomedical applications as a matrix or scaffold material for tissue engineering applications. Since, the presence of impurities can cause immunological reactions in vivo where ultimately pure materials are needed. To this end, purity of commercial-grade CMCh samples was investigated here along with their purification by a solvent/nonsolvent technique. The resulting polymer was characterized by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDX) to confirm the validity of the purification process.     

Synthesis,characterization and biological evaluation of N-substituted triazinane-2-thiones and theoretical–experimental mechanism of condensation reaction

The synthesis of triazinthions and their reactions with some nucleophilic reagents have been investigated during this scientific study. Thus, thiourea with a single component has been synthesized as a result of concomitant reactions of aldehyde and amines trials. The structure of the synthesized compounds was confirmed by ¹H, ¹³C NMR spectroscopy methods. The inhibitory effects of novel N-substituted triazinane-2-thione derivatives on acetylcholinesterase (AChE) activity were performed according to the spectrophotometric method of Ellman et al. These novel N-substituted triazinane-2-thiones derivatives were effective inhibitors of the α-glycosidase, cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and Acetylcholinesterase (AChE) enzymes with K_i values in the range of 1.01 ± 0.28 to 2.12 ± 0.37 nm for α-glycosidase, 13.44 ± 4.39 to 74.98 ± 6.25 nm for hCA I, 10.41 ± 4.8 to 72.6 ± 17.66 nm for hCA II, 36.82 ± 9.95 to 108.48 ± 1.17 nm for AChE, and 624.62 ± 100.34 to 1124.16 ± 205.14 nm for α-glycosidase, respectively.     

Trace determination of Ag(I) after reduction to Ag nanoparticles and sol–gel entrapment by alginic acid hydrogel

The main goal of this work is development of an effective analytical method for trace determination of Ag(I). The novelty of the Ag(I) preconcentration–determination method is mainly referred to the material and the enrichment–detection process (alginic acid gel phase was employed in a pH-switched sol–gel entrapment/Ag fluorescence detection). Ag(I) was reduced to Ag nanoparticles (AgNPs) and then was enriched by the alginic acid hydrogel phase. Then, the formed gel phase (containing AgNPs) was dissolved in alkali solution prior to Ag detection. The enrichment method was highly compatible with spectrofluorimetry, electrothermal atomic absorption spectrometry (ETAAS) and spectrophotometry. Optimization of the reduction-enrichment procedure was performed employing spectrofluorimetry. The linear working range (LWR) and limit of detection (LOD) for Ag(I) determination were found as 0.1–25 and 0.017 µmol L^??1, respectively. The effects of various anions, cations and organic chemicals on Ag(I) determination were spectrofluorimetrically studied. The applied enrichment-ETAAS Ag(I) determination method showed the LWR and LOD as 0.2–6.9 and 0.05 nmol L^??1, respectively. Also, an enrichment factor equal to 30.3 was obtained for the preconcentration method. The method was successfully applied to determine Ag in different water samples, jewels, antimicrobial suspensions and waste X-ray films. X-ray diffraction, transmission electron microscopy, field emission-scanning electron microscopy and EDX-mapping were also employed to characterize the entrapped AgNPs in the alginic acid gel phase. The complimentary experiments showed the alginic acid gel was also applicable for quantitative recovery of silver from the waste radiographic films.     

Improved photocatalytic degradation of reactive blue 81 using NiO-doped ZnO–ZrO2 nanoparticles

In this study, the photocatalytic degradation of Reactive Blue 81 (RB81) using synthesized NiO-doped ZnO–ZrO₂ nanoparticles under UV irradiation was investigated. Then, the products were characterized by Scanning electron microscope (SEM), X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS). The removal rate of RB81 using ZnO–ZrO₂ after 180?min of irradiation was 96.7%. Nickel oxide (NiO) was used as an additive to ZnO–ZrO₂ for improvement of RB81 degradation via photocatalysis process. Photodegradation of RB81 was achieved to 100% using ZnO–ZrO₂–NiO nanoparticles with ratio of 1:2:0.3 after 180?min of irradiation. There was a red shift in absorption bands (from 410?nm to 435?nm) observed in increasing of NiO to ZnO–ZrO₂ nanoparticle, that it might lead to a higher photocatalytic activity under visible light. Response surface methodology (RSM) was used for optimization of experimental and these results were obtained: solution pH = 3, ZnO–ZrO₂–NiO dosage = 15?mg/L, and the initial RB81 concentration = 5?mg/L. The photodegredation of RB81 followed pseudo-first order kinetic according to the Langmuir–Hinshelwood model.     

The Effect of Structure of the Clay Modifier on the Morphology and Properties of Polystyrene/Clay Nanocomposites Prepared via In Situ Suspension Polymerization

Polystyrene (PS)/organoclay nanocomposites were prepared via free radical suspension polymerization. Two kinds of organoclay were used, labeled KT and KD, modified by trimethyloctadecyl ammonium (TM) and dimethyldioctadecyl ammonium (DM) ions, respectively. Nanocomposites containing various amounts of both of the organoclay nanoparticles (1, 3, and 5 wt%) were prepared. The wide angle X-ray diffraction (WAXD) results revealed intercalation in both of the nanocomposites. The greatest improvement in thermal stability of the nanocomposites was achieved with 5 wt% of organo-MMT for both of the clays. The nanocomposite containing 3 wt% of KT organo-MMT showed the greatest improvement of storage modulus. When the organoclay content exceeded 3 wt%, the storage moduli decreased compared to the nanocomposite filled with 3 wt% of the organoclay. D-spacing calculations using Bragg's law and WAXD data showed that the KT and KD nanoparticles were intercalated within the PS matrix, but with different extents of intercalation. The styrene conversions of the as-polymerized nanocomposite samples were obtained by a gravimetric method. The results showed that conversion decreased with incorporation of organoclay in the reaction recipe. Particle size was also increased by increasing nanoclay content.