High-performance fiberglass/epoxy reinforced by functionalized CNTs for vehicle applications with less fuel consumption and greenhouse gas emissions

Carbon Nanotubes (CNTs) is among the most promising nanofiller materials that could be used for enhancing the properties of fiberglass/epoxy laminates for vehicle industries with less CO₂ emission (the key player in the climate change). However, usually the commercialized CNTs are supplied in the shape of heavily entangled tubes what leads to random dispersion of CNTs in the polymer matrix and decrease in their performance, especially at industrial scale. Within this frame, the chemical functionalization process was used in the present research to avoid this problem and to modify the surface properties of CNTs at the same time, thus improving compatibility and solubility of CNTs in epoxy solutions. Afterwards, probe sonicator (pre-dispersion), ultrasonic path (main dispersion), mechanical mixer (mixed CNTs/Epoxy solutions with hardener), and vacuum infiltration (to remove air bubbles) were used to disperse functionalized CNTs with different concentrations (in the range 0.05–0.4 wt%) in the epoxy-hardener solutions. Then, vacuum-assisted resin transfer technique followed by curing process were used to prepare 4 layers-fiberglass/CNTs/epoxy panels. The mechanical and impact properties of the prepared panels were tested according to ASTM D7025 and ISO 6603-2 standards, respectively. Also, thermal behavior of the panels was investigated using thermogravimetric (TG-DTG). Finally, the environmental performance in terms of greenhouse gas emission (GHGE) was evaluated according to ISO-14040 standard, taking the resulting strength and changes in density into account. The results showed that 0.35 wt% of FCNTs were enough to improve the strength of panels by ~60%, compared to pure sample. Which means that weight structure of vehicles can decrease by 23%. Also, fuel consumption and GHGE can decrease significantly by 16% and ~26%, respectively. In addition, thermal stability and energy impact absorption at the same concentration of CNTs were improved by 5% and 31%, respectively.     

High mechanical and thermal performance of Sasobit-modified epoxy resin,prepared via vacuum shock technique

In this study, thermal and mechanical properties of novel nanocomposite, epoxy resin reinforced with octadecylamine functionalized graphene oxide (GO-ODA) and Sasobit, prepared via creative vacuum shock technique, were investigated. By introducing 1, 3 and 5 wt% Sasobit to the neat epoxy resin, the tensile strength increased remarkably by 104%, 315% and 266%, respectively due to the unique stiff and crystalline structure of Sasobit. In addition, considerable enhancement of 125% in Young's modulus, 351% in toughness, 562% in impact resistance, ~19 °C in thermal stability and ~7 °C in glass transition temperature of epoxy resin with 3 wt% Sasobit loading was demonstrated. The composite containing 3 wt% Sasobit alone, were found to have even superior properties than GO-ODA/epoxy nanocomposite, as surprisingly 3, 2.9, 2.2 and 2 times more improvement, respectively in tensile strength, toughness, impact strength and thermal stability of epoxy resin compared to reinforcement with GO-ODA were obtained.     

Simultaneous determination of clozapine, clozapine N-oxide, N-desmethylclozapine, risperidone, and 9-hydroxyrisperidone in plasma by high performance liquid chromatography with ultraviolet detection

A simple high performance liquid chromatography techniques with ultraviolet detection (HPLC–UV) method is described for the simultaneous determination of clozapine (CZP), clozapine N-oxide (CNO), N-desmethylclozapine (NCZ), risperidone (RSP) and 9-hydroxyrisperidone (9-OHRSP) in human plasma. After extraction process, the analytes were separated on a C₁₈ column (150 mm×3.9 mm i.d.) by the mobile phase (methanol–water–dimethylamine, 60:40:0.04 (v:v:v)). Relative recoveries of five analytes were quantitative. The precision and accuracy of intra- and interday assays were all below 8.2% for R.S.D. and 5.6% for RE, respectively. Based on 1 ml of plasma, the limits of detection were 2.0 ng/ml for CZP, 0.2 ng/ml for CZP N-oxide, 1.0 ng/ml for NCZ, 1.0 ng/ml for RSP, and 0.5 ng/ml for 9-OHRSP (S/N=3). The calibration curves were linear (r≥0.988). This method was applied to therapeutic drug monitoring of schizophrenia patients receiving CZP or RSP therapy.     

超高效液相色谱/静电场轨道阱高分辨质谱法同时测定塑料食品接触材料中光稳定剂和抗氧化剂的特定迁移量

建立了超高效液相色谱/静电场轨道阱高分辨质谱同时测定塑料食品接触材料中多种光稳定剂和抗氧化剂特定迁移量的方法。采用30 g/L乙酸、体积分数分别为10%、20%、50%的乙醇和油类模拟物(异辛烷)这5种食品模拟物对塑料食品接触材料进行处理,对处理液进行超高效液相色谱/静电场轨道阱高分辨质谱分析,外标法定量。该方法测定的40种目标化合物在相应的范围内均具有良好的线性关系,相关系数均大于0.998,定量限为0.01~1.00μg/L。考察了上述5种食品模拟物中光稳定剂和抗氧化剂的特定迁移量,平均加标回收率为81.46%~94.53%,相对标准偏差为3.25%~9.99%。应用该方法对市售塑料食品接触材料进行了测定,结果在部分样品中检出了不同含量的光稳定剂和抗氧化剂。该方法灵敏度高,定量限低,满足塑料食品接触材料中光稳定剂和抗氧化剂特定迁移量的检测要求。     

Preparative isolation and purification of ginsenosides Rf,Re, Rd and Rb1 from the roots of Panax ginseng with a salt/containing solvent system and flow step-gradient by high performance counter-current chromatography coupled with an evaporative light scattering detector

Ginseng is a popular herb worldwide and has had varied uses in traditional Asian medicine for thousands of years. There are several different species of the herb, but all share the same constituents. Ginsenosides, the most extensively studied chemical components of ginseng, are generally considered to be one of the most important active ingredients of the plant. In this study, we have developed fast and efficient methodology for isolation of four known ginsenosides Rf, Rd, Re and Rb1 from Ginseng by high performance counter-current chromatography (HPCCC) coupled with evaporative light scattering detection (ELSD). The crude sample for HPCCC was purified firstly from a ginseng extraction using macroporous resin. The enriched saponin fraction (480 mg) was separated by using methylene chloride–methanol–5 mM aqueous ammonium acetate–isopropanol (6:2:4:3, v/v,) as the two-phase solvent system and yielded 10.7 mg of Rf, 11.0 mg of Rd, 13.4 mg of Re and 13.9 mg of Rb1. The purity of these ginsenosides was 99.2%, 88.3%, 93.7% and 91.8%, respectively assessed by HPLC-DAD-ELSD, and their structures were characterized by electrospray ionization mass spectrometry (ESI-MS) and compared with standards. Ammonium acetate was used to shorten the separation time and eliminate emulsification together with a flow step-gradient. The salt can be removed by re-dissolving the sample using acetone.