A new amperometric biosensor for fructose determination based on epoxy-graphite-TTF-TCNQ-FDH-biocomposite

In this work a novel amperometric biosensor for fructose determination in solutions was developed. The device was constructed by the incorporation of a tetrathiofulvalene-tetracyanoquinodimethane organic conducting salt and fructose dehydrogenase enzyme, include in a polymeric matrix of epoxy resin and graphite powder. Because of the electrocatalytic function of the salt, the direct transfer of the electron between the reduced prosthetic group (PQQH₂) of the enzyme and the transducing material, was verified at a low working potential (150 mV vs. Ag/AgCl), where the interfering reactions were minimized. The response time at 90% of the steady state value was less than 20 s. The current response was directly proportional to the D-fructose concentration from 0.01 to 0.3 mmol/l with a detection limit of 0.005 mmol/l (signal/noise of 3) and a sensitivity of 1.9985 μA/mmol. The biosensor sensitivity diminishes when its surface is not polished between successive determinations, and remains constant (rsd=1.85, n=10) when the surface is polished between determinations. The effects of temperature and pH on the biosensor response were studied and analyzed; also the properties of the enzyme (Km _ap, I _max, Q₁₀) were determinate in this work. The biosensor was used to determine fructose in high fructose syrups and there were not significant differences between these results and those obtained by HPLC (p≤0.05). During 4 months, in intermittent determinations the biosensor kept 100% of its original sensitivity and after 18 months stored at 4°C, it only lost 32% of its sensitivity. The simplicity, low working potential, high stability and good performance of this biosensor shows a great potential for its use in the fructose determination.     

σ-单键连接的TTF吡啶衍生物对Pb~(2+)的识别

设计合成了一类σ-单键连接的TTF吡啶化合物T4Py和TB,并研究了化合物T4Py对离子的识别作用.结果发现Pb2+离子能够引起T4Py的溶液颜色1、HNMR以及电化学CV的显著变化.     

基于TTF技术的UG刻字工具开发

在模具设计中,常需在零件上刻编号、铭牌等信息,以便标识和装配,手工处理繁琐费时.通过对TTF字符轮廓描述模型进行分析研究,并利用轮廓并运算处理算法,对字符原始轮廓信息进行加工,获取三维造型所需的封闭并无自相交的曲线.在UG三维设计软件平台上,利用UG/Open API开发出刻字工具,以解决零件刻字的效率问题.该工具支持用户自定义属性、自动生成字符槽特征,对镶块、顶针等有规则的零件具有批量刻字功能.     

支持变形的维哈柯文网页嵌入技术

维哈柯文网页嵌入技术以维哈柯文OpenType字库为基础,通过特定的SDK工具将其转换为Web通用的网页嵌入字体格式,结合维哈柯文输入法,完美的解决了维哈柯文在网络时代的快速、准确、优美的传播。使用本技术,客户端无需在额外安装本地维哈柯文字库,解决了维哈柯文在网络时代进行在线收集、管理、检索、录入、编辑、保存等问题。     

Integrating TTF and UTAUT2 theories to investigate the adoption of augmented reality technology in education: Perspective from a developing country

Augmented reality (AR) has gained increased recognition in varying fields, in particular educational contexts. In the wake of the Covid-19 pandemic, home-based learning becomes a reality and is already in place across the globe, and learning via augmented reality technology will help learners comprehend learning content in a more creative frame of mind than ever before. Very little research has examined the adoption behavior of augmented reality in developing country perspectives. Therefore, there is a pressing necessity to understand the dynamics of augmented reality adoption for the benefit of motivating and inspiring students to adopt this highly innovative and impactful type of technology in the learning process. Against this background, the authors proposed and tested a model based on integrating Task-Technology Fit (TTF) and UTUAT2 theories. The results reveal the positive effect of task technology fit, performance expectancy, effort expectancy, social influence, facilitating condition, and hedonic motivation on behavioral intention (BI) in the adoption process of augmented reality in educational settings, where price value is found to exert little influence on behavioral intention. This model explains 49% of the variance in intentional behavior to adopt AR technology in the educational context. The conclusions of this study will add to the literature more informative knowledge leading to increased awareness of the dynamics and behaviors of AR adoption in a developing country perspective. We present and discuss the theoretical contributions and practical implications of our findings.     

A framework to practical predictive maintenance modeling for multi-state systems

A simple practical framework for predictive maintenance (PdM)-based scheduling of multi-state systems (MSS) is developed. The maintenance schedules are derived from a system-perspective using the failure times of the overall system as estimated from its performance degradation trends.

The system analyzed in this work is a flow transmission water pipe system. The various factors influencing PdM-based scheduling are identified and their impact on the system reliability and performance are quantitatively studied. The estimated times to replacement of the MSS may also be derived from the developed model.

The results of the model simulation demonstrate the significant impact of maintenance quality and the criteria for the call for maintenance (user demand) on the system reliability and mean performance characteristics. A slight improvement in maintenance quality is found to postpone the system replacement time by manifold. The consistency in the quality of maintenance work with minimal variance is also identified as a very important factor that enhances the system's future operational and downtime event predictability.

The studies also reveal that in order to reduce the frequency of maintenance actions, it is necessary to lower the minimum user demand from the system if possible, ensuring at the same time that the system still performs its intended function effectively.

The model proposed can be utilized to implement a PdM program in the industry with a few modifications to suit the individual industrial systems’ needs.     

Age replacement policy in the case of no data: the effect of Weibull parameter estimation

Age replacement is a common maintenance policy when wear-out failures occur, and it is characterised by periodic replacement of components. Data on time to failure (TTF), often modelled with the Weibull function, are necessary for estimating optimal replacement intervals to minimise the total maintenance costs. In many cases, such as new components, new machines or new installations, no TTF data are available, so the Weibull parameters and optimal replacement interval cannot be estimated. To overcome this problem, these parameters can be assessed from the experience of the maintenance engineers and technicians. The aim of this study is investigating the relationship between the error in parameter estimation and additional maintenance costs related to this error. Analysis of variance (ANOVA) and multifactorial analysis are carried out for investigating the influence of these estimations on the final costs. Economic decision maps are introduced for supporting maintenance engineering in defining the maintenance policy with minimal additional cost in the case of no data being available. The analysis shows that, when no data are available, the application of the age replacement policy can result in a global saving of more than 50% compared with corrective maintenance.     

Synthesis and properties of tetrathiafulvalene-fluorescein dyads

Two donor-acceptor molecular systems consisted of tetrathiafulvalene (TTF) and fluorescein were designed and synthesized. The target compounds and their key intermediates were characterized by 1H NMR, mass spectrography, and infrared spectroscopy, respectively. The UV-vis spectra implied intramolecular interaction in their ground state. Fluorescence spectra and fluorescence lifetimes indicated the photoinduced charge transfer (PET) interaction between the TTF and fluorescein units in their excited states.     

不同类型分解炉分煤燃烧脱硝的改造和调试

中材水泥有限责任公司生产线主要的分解炉炉型有TTF型、TDF型、RSP型，他们对其均进行了分煤燃烧的脱硝改造，文章对其主要改造内容和效果进行了分析总结。