Evaluating the effect of waste material on viscoelastic characteristics of bitumen

In this research, adding waste plastics (LDPE) and crumb rubber to bitumen causes the improvement in the viscoelastic behavior of bitumen. The sample containing 3% waste LDPE and 3% CR is the optimum one, which can be resulted from the complex modulus and the phase difference results. In continuance, elastic recovery test at 25 °C was performed on samples, and it was seen that with increase of crumb rubber content, elastic recovery increases because of elastic property of crumb rubber. In sample containing 5% waste polyethylene and 3% crumb rubber elastic recovery has been approached to the desirable amounts according to existence of enough crumb rubber. Finally, for evaluation of bitumen performance in mixture with modifiers, rotational viscosity on samples was performed.     

Use of Fourier transform infrared spectroscopy to study ageing characteristics of asphalt binders

The present study aims at studying ageing characteristics of conventional bitumen, polymer modified bitumen (PMB) and warm mix asphalt (WMA) by using FTIR. Results of obtained FTIR spectrum were quantified by calculating different indices and finally based on these indices ageing index of the binders for short- and long-term ageing were calculated. Results showed ageing increased amount of complex and high molecular weight components of the binders. PMB was found to have greater ageing resistance than conventional asphalt binders. In case of WMA, results found to be inconclusive, requiring further investigation.     

发育时间对橡胶沥青性能的影响研究

制备了不同发育时间的胶粉改性沥青样品,并通过动态剪切流变仪（DSR）和弯曲梁流变仪（BBR）等对其进行分析。用得到的高温指标（黏度、软化点、车辙因子等）和低温指标（延度、蠕变劲度）分析发育时间对胶粉改性沥青性能的影响。结果表明：胶粉改性沥青样品的高温性能和低温性能均较好;但随发育时间的增加,高温性能和低温性能有所下降,温度敏感性变大,胶粉和沥青的相容性变好,热储存稳定性变好。     

A comparative evaluation of crumb rubber and devulcanized rubber modified binders

One of the most prominent uses of ground tire rubber (GTR) is in rubber-modified asphalt industry. Besides improving performance properties of binders, GTR induces some drawbacks like weak storage stability and inferior low temperature (LT) performance. This study sought to rectify these shortcomings through using devulcanized rubber (DVR) in place of common GTR. Binder performance grading, multiple stress creep and recovery, and storage stability tests were conducted. More resistance against traffic loads at high temperatures was observed as DVR's advantages over GTR, while its weaker LT characteristics and lower storage stability can prevent it from being a viable alternative.     

Auto-microfluidic thin-film chip for genetically modified maize detection

As a thin-film chip method, reverse dot blot hybridization (RDBH) has been employed to detect hazardous substances, but an automatic RDBH instrument with low workload, high accuracy and stability is still urgently needed. This paper presents our newly-developed auto-microfluidic thin-film chip (AMTC) method for multiplex screening of genetically modified (GM) maize. With specific DNA probes for genetically modified (GM) maize being immobilized on a square nylon thin-film, it was placed into a micro-reaction cell of the AMTC device. Then biotin-labeled PCR products with target DNA fragments for template amplification were added to the micro-reaction cell using a microfluidic system. When the PCR products passed the square nylon thin-film, the target DNA fragments were captured by the complementary action of DNA, where the signal was visualized with streptavidin link-coupled alkaline phosphatase color development kit. The sensitivity of GM maize detection reached 0.1% quality percentage and its stability and consistency could satisfy the requirements for practical applications. Performance advantages of the ATMC are manifold, being embodied in aspects such as easy and straightforward operation, low costs and less workload.     

Detection of unapproved genetically modified potatoes in Korea using multiplex polymerase chain reaction

Several genetically modified (GM) potato cultivars with improved traits such as increased amylopectin levels, decreased asparagine levels, and reduced incidence of black spot have been developed. In this study, we describe a multiplex polymerase chain reaction (PCR) method specific for four GM potato events (EH92-527-1, AM04-1020, PH05-026-0048, and E12) that are unauthorized in Korea. The UDP-glucose pyrophosphorylase (UGPase) gene was used as the endogenous reference gene. The specificity of the primer sets was evaluated using GM potatoes and other GM crops. The limit of detection in the developed multiplex PCR was confirmed to be approximately 0.04% (w/w). Thirty-three commercial products containing potato ingredients were tested by the multiplex PCR assay, and GM potato event E12 was found in one of the 33 samples. This result suggested that the developed PCR method could be used to effectively identify unauthorized GM potatoes in Korea.     

An improved BEM model for the power curve prediction of stall‐regulated wind turbines

Blade element momentum (BEM) theory is the standard computational technique for the prediction of power curves of wind turbines; it is based on the two‐dimensional aerodynamic properties of aerofoil blade elements and some corrections accounting for three‐dimensional wing aerodynamics. Although most BEM models yield acceptable results for low‐wind and pitch‐controlled regimes where the local angles of attack are small, no generally accepted model exists up to date that consistently predicts the power curve in the stall regime for a variety of blade properties and operating conditions. In this article we present a modified BEM model which satisfactorily reproduces the power curves of four experimental wind turbines reported in the literature, using no free fit parameters. Since these four experimental cases comprehend a great variety of conditions (wind tunnel vs field experiments, different air densities) and blade parameters (no twist and no taper, no taper but twist, both twist and taper, different aerofoil families), it is believed that our model represents a useful working tool for the aerodynamic design of stall‐regulated wind turbines. Copyright © 2004 John Wiley & Sons, Ltd.     

改性膨润土防渗浆材的性能研究

以聚乙烯醇为改性剂制得有机化膨润土,并与水泥、粉煤灰及辅助添加剂组成防渗浆材,通过正交试验法,分析了浆材固结体的渗透性、吸附阻滞性和耐久性。结果表明,以改性膨润土代替天然膨润土获得的浆材具有更低的渗透系数、更好的吸附阻滞性及耐腐蚀性,完全满足抗渗要求。     

含色散项Zabolotskaya-Khokhlov方程的对称、约化、精确解和守恒律

利用修正的Clarkson-Kruskal (CK)直接方法得到了含色散项的Zabolotskaya-Khokhlov(简写为DZK)方程的对称、约化和一些精确解,包括双曲函数解,有理函数解,三角函数解等,同时得到了该方程的守恒律.     

双酚S型苯并恶嗪改性酚醛树脂模塑料的性能研究

以双酚S为原料,采用溶剂法合成了一种含砜基的苯并恶嗪(BOZ–S),并用不同长度的高性能维纶短切纤维(PVAF)为增强材料,通过预浸料模压成型制备出BOZ–S改性酚醛树脂(PF)模塑料。利用傅里叶变换红外光谱仪、核磁共振仪、差示扫描量热仪以及扫描电子显微镜等分别对BOZ–S的单体结构、PF/BOZ–S改性体系的固化特性、改性PF模塑料的力学性能、热性能以及冲击断口进行了分析研究。结果表明,成功合成出了预期结构的BOZ–S,且固化时存在两种放热反应;改性树脂体系的各项性能与纯PF相比均有明显提升,且纤维的长度越长,模塑料的力学性能提升越大,其中PF/BOZ–S质量比为80/20、纤维长度为36 mm时,体系的综合性能最佳,冲击强度和弯曲强度分别为88.4 k J/m~2和175.9 MPa,弯曲弹性模量达到8.8 GPa,马丁耐热温度为164.3℃。