ZnO纳米管有序阵列与Cu2O纳米晶核壳结构的光电化学性能及全固态纳米结构太阳电池研究简

采用电化学方法在铟锡氧化物(ITO)导电玻璃基底上制备了高度有序的ZnO纳米管阵列,然后在ZnO纳米管阵列上电化学沉积Cu2O纳米晶颗粒,获得了一维有序Cu2O/ZnO核壳式纳米阵列结构,通过控制Cu2O纳米晶的沉积电量得到不同厚度的Cu2O壳层,并对该核壳式纳米阵列的形貌和结构进行了分析. 以Cu2O/ZnO一维核壳式纳米阵列结构为光电极组装全固态纳米结构太阳电池,研究了Cu2O壳层厚度对光电极光吸收性能、光电性能以及组装电池光伏性能的影响,优化了电池中对电极材料的喷金厚度. 结果表明,以Cu2O沉积电量为1.5 C的Cu2O/ZnO为光活性层,以4 mA电流下真空镀金20~25 min的铜基底为对电极组装的简易太阳电池最高可获得0.013%的光电转换效率.     

多频超声反应槽连续强化酸化油酯交换制备生物柴油研究

以平均酸值高达33.07 mgKOH/g不可食用的廉价酸化油为原料,利用自行设计的多频超声溢流槽连续强化酯交换反应生物柴油生产装置,先后经预酯化、酯交换两步反应,高效、低耗的制备生物柴油。主要考察了室温下物料流量(停留时间)、超声功率、超声频率及组合、KOH用量、醇油物质的量比对酯交换反应的影响及单位产品能耗。结果表明,多频组合超声辐射比单频更有利于生物柴油的制备;预酯化后的油料在流量为25 L/h(物料停留时间为54 min),催化剂(KOH)用量为1.2%(质量分数),醇油物质的量比为6∶1和各反应槽功率为200 W的条件下,甲酯产率达96.83%。50 L废弃酸化油能制得符合国标GB19147—2009的生物柴油48L,整个生物柴油制备过程总耗时和总耗电量仅为8.667 h、5.42 kWh。     

Rapid quantitative analysis of individual anthocyanin content based on high‐performance liquid chromatography with diode array detection with the pH differential method

A new quantitative technique for the simultaneous quantification of the individual anthocyanins based on the pH differential method and high‐performance liquid chromatography with diode array detection is proposed in this paper. The six individual anthocyanins (cyanidin 3‐glucoside, cyanidin 3‐rutinoside, petunidin 3‐glucoside, petunidin 3‐rutinoside, and malvidin 3‐rutinoside) from mulberry (Morus rubra) and Liriope platyphylla were used for demonstration and validation. The elution of anthocyanins was performed using a C₁₈ column with stepwise gradient elution and individual anthocyanins were identified by high‐performance liquid chromatography with tandem mass spectrometry. Based on the pH differential method, the high‐performance liquid chromatography peak areas of maximum and reference absorption wavelengths of anthocyanin extracts were conducted to quantify individual anthocyanins. The calibration curves for these anthocyanins were linear within the range of 10–5500 mg/L. The correlation coefficients (r²) all exceeded 0.9972, and the limits of detection were in the range of 1–4 mg/L at a signal‐to‐noise ratio ≥5 for these anthocyanins. The proposed quantitative analysis was reproducible with good accuracy of all individual anthocyanins ranging from 96.3 to 104.2% and relative recoveries were in the range 98.4–103.2%. The proposed technique is performed without anthocyanin standards and is a simple, rapid, accurate, and economical method to determine individual anthocyanin contents.     

铂修饰的{001}面暴露的二氧化钛纳米片阵列的制备和光催化性能

采用有机溶剂热法在FTO衬底上制备{001}面暴露的单晶锐钛矿相TiO2纳米片阵列,通过FESEM和XRD研究样品的形貌和晶体结构. 与水热法制备的纳米片阵列相比,有机溶剂热法制备的样品取向性更好. 采用光沉积方法在纳米片阵列上沉积Pt,所得到的Pt纳米颗粒粒径更为均匀,并且更容易沉积在{001}面上. 所负载的Pt 纳米颗粒增强了TiO2纳米片的光吸收性能,同时大大减弱了光致发光强度. 在光催化性能测试中,具有最优负载量的样品催化性能提高了一倍. 与传统的Pt负载相比,{001}面的最优负载量显得相当小,这可能源于高活性{001}面的原子结构.     

Effect of hybrid fillers on the mechanical behavior of polypropylene based hybrid composites

The present study investigates the effect of hybrid fillers such as graphene nanoplatelets (GnPs) and Titanium di-oxide (TiO₂) in polypropylene (PP) composites on the mechanical properties. The compatibilizing agent of Maleic anhydride grafted polypropylene (MAPP) are used in the polypropylene based composites to increase the interfacial adhesion between matrix and fillers. The experiments are designed according to L₁₆ orthogonal array (OA) based design of experiments (DOE). The parameters selected for this study are GnPs, TiO₂ and MAPP with four different levels are used.By using Orthogonal array and Taguchi based experimental design, the performance characteristics of tensile modulus, tensile strength, elongation at break and toughness can be analyzed with more objective through a small set of experiments.Taguchi based analysis are used to find out the optimal parameters to maximize the tensile properties for the GnPs and TiO₂ reinforced PP hybrid composites. Further, analysis of variance (ANOVA) is investigated to identify the most significant parameters which influence the mechanical properties.From the analysis it was found that the optimal parameters of 3 ?wt% GnPs, 2 ?wt% TiO₂ and 6 ?wt% MAPP for maximum tensile modulus and tensile strength. The most significant parameter for tensile modulus and tensile strength is GnPs followed by TiO₂ and MAPP according to ANOVA analysis.     

Supramolecular optical sensor arrays for on-site analytical devices

Supramolecular optical chemosensors are useful tools in analytical chemistry for the visualization of molecular recognition information. One advantage is that they can be utilized for array systems to detect multiple analytes. However, chemosensor arrays have been evaluated mainly in the solution phase, which limits a wide range of practical applications. Thus, appropriate solid support materials such as polymer gels and papers are required to broaden the scope of the application of chemosensors as on-site analytical tools. In this review, we summarize the actual approaches for the fabrication of solid-state chemosensor arrays combined with powerful data processing techniques and portable digital recorders for real-world applications.     

Ultrasound as a Promising Tool for the Green Extraction of Specialized Metabolites from Some Culinary Spices

Spices are a popular food of plant origin, rich in various phytochemicals and recognized for their numerous properties. The aim of the study was to evaluate the antioxidant and antimicrobial activity, as well as the content of specialized metabolites, of aqueous extracts of three spice species––garlic (Allium sativum L.), ginger (Zingiber officinalle L.) and turmeric (Curcuma longa L.)––prepared by green extraction methods. Ultrasound treatment increased the chromaticity parameter b value of turmeric and ginger extracts, thus indicating a higher yellow color predominantly due to curcuminoids characteristic of these species. Ultrasound-assisted extraction significantly increased the content of total soluble solids, phenolic compounds, total carotenoids and vitamin C. The temperature of the system was also an important factor, with the highest (70 °C) conditions in ultrasound-assisted extraction having a positive effect on thermolabile compounds (vitamin C, phenolics, total carotenoids). For example, turmeric extract treated with ultrasound at 70 °C had up to a 67% higher vitamin C content and a 69.4% higher total carotenoid content compared to samples treated conventionally at the same temperature, while ginger extracts had up to 40% higher total phenols. All different concentrations of spice extracts were not sufficient for complete inhibition of pathogenic bacterial strains of Salmonella, L. monocytogenes and S. aureus; however, only garlic extracts had an effect on slowing down the growth and number of L. monocytogenes colonies. Spice extracts obtained by ultrasonic treatment contained a significantly higher level of bioactive compounds and antioxidant capacity, suggesting that the extracts obtained have significant nutritional potential and thus a significant possibility for phytotherapeutic uses.     

用于气象观测的阵列式温度传感器流体动力学分析与实验研究

传统百叶箱和防辐射罩内部的温度传感器受到太阳辐射会导致其温度高于大气真实温度, 升温量可达0.8 K甚至更高. 为提高大气温度观测精度, 本文设计了一种阵列式温度传感器. 利用计算流体动力学方法分析计算该传感器在不同环境条件下的辐射升温量, 采用遗传算法对计算结果进行拟合, 获得辐射升温量修正方程. 为验证阵列式温度传感器的实际性能, 研制了强制通风温度测量平台. 将阵列式温度传感器、配有传统防辐射罩的温度传感器和强制通风温度测量平台置于相同环境下, 进行大气温度观测比对实验. 配有传统防辐射罩的温度传感器辐射升温量平均值为0.409 K; 与前者相比, 阵列式温度传感器的辐射升温量仅为0.027 K. 这种阵列式温度传感器可将辐射升温引起的误差降低约93%. 辐射升温量实验测量值与修正方程修正值之间的平均偏移量为0.0174 K, 均方根误差为0.0215 K, 该结果验证了计算流体动力学方法与遗传算法的准确性. 如果配合计算流体动力学方法与遗传算法, 温度测量精度有进一步提高的潜力.     

A realization of digital wireless transmission for MRI signals based on 802.11b

In this paper, a digital wireless transmission system based on 802.11b standard for magnetic resonance imaging (MRI) application is designed and built for the first time to eliminate the interference aroused by coil array cables. The analysis shows that the wireless receiver has a very high sensitivity to detect MRI signals. The modulation technique of differential quadrature phase shift keyed (DQPSK) can be applied to MRI data transmission with rate of 2 Mbps and bandwidth of 2 MHz. The bench test verifies that this wireless link has a dynamic range over 86 dB supporting up to 3 T MRI system data transmission. The 2D spin echo imaging of phantom is performed and the SNR of the image obtained by the wireless transmission can be comparable with that got by the coaxial cables.