亨氏“苏丹红事件”的危机公关

"苏丹红一号"飓风席卷亨氏在英国查出某些调味料含有致癌物"苏丹红一号"工业添加剂后,亨氏美味源(广州)食品有限公司接连被查出6种含有"苏丹红一号"的问题产品。刚刚平静了不久的"食品安全"海面,又掀起了巨浪。2004年,"食品安全"、"惊涛骇浪",巨能钙含双氧水、特富龙致癌、味事达含有毒物质、阜阳劣质奶粉、龙口毒粉丝、毒面     

有机非线性光学晶体POM的研制

本文探索了POM的合成条件和单晶生长条件,测定了单晶的透光曲线和光损伤阈值.计算了POM单晶Ⅰ类和Ⅱ类位相匹配曲面轨迹,给出了实验验证结果.     

LBO Ⅰ类临界相位匹配倍频671 nm激光器

采用 1W国产半导体激光二极管抽运Nd∶YVO4 ,Ⅰ类临界相位匹配LBO晶体腔内倍频 ,获得了 74mW的6 71nm红激光输出的实验结果。分析和实验表明 ,LBOⅠ类临界相位匹配是获得高效率倍频红光输出的实用方法。     

主客体掺杂的偶氮类聚合物

摘　要: 采用旋转甩膜法制备了主客体掺杂型的偶氮类聚合物薄膜, 构成薄膜的光学活性生色团包括分散红1、分散橙 25、分散黄7、分散红54, 基体为聚甲基丙烯酸甲酯( PM MA) 或聚碳酸酯( PC) 。利用扫描电镜( SEM) 、X 射线衍射 ( XRD) 、差示扫描量热计( DSC) 、红外光谱法( IR) 、紫外-可见吸收谱仪和显微硬度仪等对样品的表面、染料的结晶性、玻 璃化转变温度、掺杂聚合物的结构、薄膜的吸收谱以及硬度进行了分析。并系统研究了工艺条件对偶氮类聚合物薄膜的 全光极化特性的影响。实验表明, 分散染料浓度越大光极化产生的二阶非线性效应越强, 这与单位面积内聚合物薄膜中含有较高浓度的分散红有关。通过普通热处理的聚合物薄膜样品, 在避光保存的条件下, 产生的全光极化效果最明显。总 之, 偶氮类聚合物薄膜全光极化下的二次谐波强度与其制备过程中的参数有密切的关系。     

主客体掺杂的偶氮类聚合物薄膜的制备和全光极化特性

采用旋转甩膜法制备了主客体掺杂型的偶氮类聚合物薄膜．构成薄膜的光学活性生色团包括分散红1、分散橙25、分散黄7、分散红54,基体为聚甲基丙烯酸甲酯(PMMA)或聚碳酸酯(PC)。利用扫描电镜(SEM)、X射线衍射(XRD)、差示扫描量热计(DSC)、红外光谱法(IR)、紫外-可见吸收谱仪和显微硬度仪等对样品的表面、染料的结晶性、玻璃化转变温度、掺杂聚合物的结构、薄膜的吸收谱以及硬度进行了分析。并系统研究了工艺条件对偶氮类聚合物薄膜的全光极化特性的影响。实验表明,分散染料浓度越大光极化产生的二阶非线性效应越强,这与单位面积内聚合物薄膜中含有较高浓度的分散红有关。通过普通热处理的聚合物薄膜样品,在避光保存的条件下,产生的全光极化效果最明显。总之,偶氮类聚合物薄膜全光极化下的二次谐波强度与其制备过程中的参数有密切的关系。     

天青Ⅰ敏化的红敏光致聚合物全息存储特性

为寻找一种新型的红敏光致聚合物,用干法处理制备了一种天青Ⅰ敏化的光致聚合物材料,并研究了它的全息存储特性.用He-Ne激光器632.8 nm波长的光对材料进行曝光,通过实验装置测量和相应的公式计算,得到材料的透过率、衍射效率、感光灵敏度以及折射率调制度,发现该材料最大衍射效率达到了66%,材料的最佳厚度为140μm,最大透过率接近80%,最大感光灵敏度为1.5×10-3cm2/mJ,最大折射率调制度为9.7×10-4,将模拟图像存入样品,得到的透射图像与衍射再现图像保真度较高,所有这些结果表明该光致聚合物适合用于高密度全息存储.     

压电传感实时监测氯霉素分子印迹聚合物的原位合成

氯霉素是一种广谱抗菌药物,但食物中的氯霉素残留物质对人类的健康构成了巨大威胁。该问题已引起国际组织和世界上许多国家和地区的高度重视。通过压电传感器检测残余的氯霉素,具有无需适用放射性材料和预处理时间短的优势。因此,合成人工模拟单克抗体——氯霉素分子印记聚合物非常有意义。实验在10μL的压电传感器的金电极上,原位合成氯霉素印迹聚合物。实验结果表明,聚合反应过程是二级反应。     

求生手册食品版

如今,我们几乎时时都会面临各种触目惊心的问题食品,苏丹红鸭蛋、孔雀绿鱼虾、三聚氰胺奶粉、地沟油、染色花椒、瘦肉精、假牛肉频繁曝出,还有最近的老鼠羊肉,我们被这些形形色色的毒食品包围了,一个个食品安全危机正时核刻威胁着我们的切身利益,赶紧准备几款食品App开辟一条求生之路吧……01问题食品早曝光面对近乎完全沦陷的问题食品,除了束手无策地妥协外我们还能做点什么?现在不用烦恼了,为你的手机配备一款问题食品曝光App,咱们便可及时识别被曝光的问题食品,将它们统统拒之门外!     

高稳定性的偶氮聚合物薄膜光致取向与弛豫的研究

合成了一种新型的偶氮聚合物,它是由吡啶基团和4-腈基-4′-羟基偶氮苯聚合而成.搭建了偶氮聚合物薄膜光致双折射探测光路系统,并测量了吡啶基团和4-腈基-4′-羟基偶氮苯的摩尔比分别为O,0.25,0.5,0.75,1的偶氮聚合物薄膜的光致取向和弛豫曲线,并做了反复写入和擦除实验以及老化实验.实验结果表明:这种偶氮吡啶聚合物光致取向十分稳定,两种单体的摩尔比越高,偶氮聚合物双折射值越大.值得关注的是摩尔比低于50％时,偶氮聚合物薄膜弛豫表现为曲线缓慢下降最后趋向平衡.而当摩尔比高于50％时,偶氮聚合物关闭泵浦光后曲线缓慢上升最后趋向平衡,这个实验结果说明了摩尔比超过50％的偶氮聚合物其保存写入信息的能力增强了,因而也更稳定了.     

基于差分喇曼光谱快速鉴别食品塑料包装袋

为了快速鉴别案件现场残留的食品塑料包装袋样本,采用差分喇曼光谱法结合系统聚类分析方法,对46个不同来源、不同系列的食品塑料包装袋样本进行了分析检验.结果表明,依据差分喇曼光谱图中特征峰的不同,可以有效区分不同来源的食品塑料包装袋样本;同时结合系统聚类分析法,可将46个样本分为17类.该方法不破坏检材、重现性好,实验结果...     

Impact of molecular weight of polymers and shear rate effects for nanoimprint lithography

Linear polystyrene of different weight averaged molecular weight (M_w = 58 kg/mol and 353 kg/mol) and a narrow molecular weight distribution was imprinted to point out differences in the flow behaviour caused by the polymer’s molecular weight in a typical hot embossing/thermal nanoimprint process. Residual layer thickness and uniformity as well as defects were taken as a measure to qualify the imprint process. Since polymer viscosity is addressed as the main material parameter, a full thermo-mechanical characterisation of the two polymers via parallel plate dynamic viscosimetry was performed prior to imprint. The main process parameter responsible for viscosity, the temperature, was varied from about 30 to 150 K above the glass transition. In addition the amount of polymer supplied for the process was varied, i.e. the initial spin-coated polymer layer thickness. Situations representing ‘underfilling’, ‘filling’ and ‘overfilling’ of the stamp cavities in specific regions were investigated. Squeezed flow simulations were performed taking into account the increase of pattern size and the filling of cavities during the ongoing imprint, which have substantial impact on the residual layers obtained. The results show that shear thinning is an issue in a high pressure hot embossing system. It governs the initial phase of the imprint featuring a rapid decrease of the polymer height. From theoretical considerations, a model could be derived for the imprint procedure under shear thinning in a constant pressure system which was able to interpret the observed phenomena. Despite the macroscopic nature of the thermo-mechanical analysis, the standard viscosimetric data for the polymers appeared to be sufficient to understand the experimental results.     

Fingerprint stamp for evaluation of polymer flow time constants in thermal nanoimprint

In order to develop an easy to handle, low-cost procedure to derive imprint-relevant characteristic polymer data from simple imprint experiments, a fingerprint stamp was designed and tested. It contains line and dot structures of different, well-graded sizes in the micron range, where the gaps in between are chosen as to assure independent intrusion of the single patterns into the polymer layer. By imprint of this stamp into a well-characterised polymer, PS 350k, a feasibility test was performed. A pattern size dependent change of the imprint characteristics was observed during the imprint under high-shear into thin layers. This is taken as a hint that polymer characterisation from such experiments is indeed possible. Such data can be adopted to optimise an imprint process for mixed pattern sizes ranging from the micron down to the nanometre scale.     

A Zipper‐Like On/Off‐Switchable Molecularly Imprinted Polymer

A zipper‐like on/off‐switchable molecularly imprinted polymer is reported. This unique imprinted polymer was composed of template‐imprinted polymeric networks that incorporate zipper‐like interactions between poly(acrylamide) (PAAm) and poly(2‐acrylamide‐2‐methyl propanesulfonic acid) (PAMPS). This polymer showed marginal recognition ability towards the imprint species under low temperature conditions, due to the interpolymer interaction between PAAm and PAMPS, which inhibited access to the imprinted networks. In contrast, at relatively high temperatures (such as 40 °C), the polymer demonstrated significant molecular recognition ability towards the imprint species resulting from the dissociation of the interpolymer complexes of PAAm and PAMPS, which enabled access to the imprint networks. Unlike previously reported PNIPAm‐based imprinted polymers, which demonstrate alterable molecular recognition simply because of the thermosensitive hydrophilicity/hydrophobicity of PNIPAm, this polymer employed a zipper‐like supramolecular architecture between PAAm and PAMPS, thereby enabling switchable molecular recognition.     

铟酞菁/氧化石墨烯高分子材料的制备及非线性光限幅性能研究

通过共价键合将二氨基二枯丁苯氧基氯代铟酞菁（Pc）与羧基化氧化石墨烯（GO-COOH）键合在一起，得到二氨基二枯丁苯氧基氯代铟酞菁-氧化石墨烯键合产物（Pc-GO-COOH），并以键合产物为原料反应得到引发剂。以甲基丙烯酸甲酯（MMA）为聚合反应单体，通过原子转移自由基聚合（ATRP）反应得到四种不同分子量的聚合物样品。采用凝胶渗透色谱（GPC）对聚合物分子量分布测试，结果表明，所制备的聚合物的分子量分布范围较窄，聚合反应具有良好的可控性。采用Z-扫描方法对聚合物样品溶液进行的三阶非线性测试结果表明，所制备的聚合物具有优良的三阶非线性光学性质，且当聚合物的分子量分别为9 063和12 196时，三阶非线性极化率值分别为8.1×10-11、2.1×10-11 esu。同时对聚合物样品的光限幅性能测试结果表明，两种样品的有效激发态与基态吸收截面比分别为2.69和2.20，具有较好的光限幅能力，具有较大的应用前景。     

低温纳米压印技术制备微纳图案的研究

纳米压印需要将聚合物加热到它的玻璃化温度以上,然后用印章压印使其复制印章图案.采用低玻璃化温度的SU-82000.1和Hybrane胶体转移图案,能够在低温、甚至室温下实现微纳图案的转移.采用的印章制备方法是聚焦离子束(FIB)直接在衬底上制备图案,从而避免了传统工艺中效率较慢的电子束加工和取消了反应离子刻蚀步骤;并且采用FIB方法可同时在衬底上制备微米、纳米尺度的图案.实验结果表明用FIB方法可以得到比较均匀致密的微纳米图案印章,经过低温纳米压印后可成功地实现微纳图案的复制.     

纳米压印光刻胶

光刻胶是纳米压印的关键材料,其性能将影响压印图形复制精度、图形缺陷率和图形向底材转移时刻蚀选择性。提出了成膜性能、硬度黏度、固化速度、界面性质和抗刻蚀能力等压印光刻胶的性能指标。并根据工艺特点和材料成分对光刻胶分类,介绍了热压印光刻胶、紫外压印光刻胶、步进压印式光刻胶和滚动压印式光刻胶的特点以及碳氧类纯有机材料、有机氟材料、有机硅材料做压印光刻胶的优缺点。列举了热压印、紫外压印、步进压印工艺中具有代表性的光刻胶实例,详细分析了其配方中各组分的比例和作用。介绍了可降解光刻胶的原理。展望了压印光刻胶的发展趋势。     

Structure size dependent recovery of thin polystyrene layers in thermal imprint lithography

Thermal imprints into polymer layers, which are thin compared to the structure height of the stamp provide the advantage that minimum residual layers can be achieved. On the other hand, due to the specific properties of thermoplastic polymers, recovery, i.e. a release of stored imprint energy, may occur after separation of sample and stamp. The intensity of this recovery strongly depends on the imprint temperature. Unfortunately a reduction of recovery by means of increased imprint temperature often generates other problems like unwanted physical self-assembly of the polymer.Another parameter that affects the development of recovery is the structure size of the imprinted patterns. This contribution is about the structure size dependency of the intensity of polymer recovery. By means of lift-off imprints of different structure sizes and types are tested after the imprint at two different temperatures.     

Strongly Dipolar Polythiourea and Polyurea Dielectrics with High Electrical Breakdown,Low Loss,and High Electrical Energy Density

Dielectric materials with high electric energy density and low loss are of great importance for applications in modern electronics and electrical systems. Strongly dipolar materials have the potential to reach relatively higher dielectric constants than the widely used non-polar or weakly dipolar polymers, as well as a much lower loss than that of nonlinear high K polymer dielectrics or polymer–ceramic composites. To realize the high energy density while maintaining the low dielectric loss, aromatic polythioureas and polyureas with high dipole moments, high dipole densities, tunable molecular structures and dielectric properties were investigated. High energy density (>24 J/cm³), high breakdown strength (>800 MV/m), and high charge–discharge efficiency (>90%) can be achieved in the new polymers. The molecular structure and film surface morphology were also studied; it is of great importance to optimize the fabrication process to make high-quality thin films.     

mr-NIL 6000LT – Epoxy-based curing resist for combined thermal and UV nanoimprint lithography below 50 °C

The aim of the work presented here was to develop curing polymers for nanoimprint lithography (NIL) enabling short cycle time, low imprint temperature, and an isothermal imprint process. The result is mr-NIL 6000LT: A photochemically curing polymer system for isothermal imprinting by combined thermal and UV nanoimprint lithography. It allows a lower imprint temperature than materials presented previously [C. Schuster, M. Kubenz, F. Reuther, M. Fink, G. Grützner, mr-NIL 6000 – New epoxy-based curing resist for efficient processing in combined thermal and UV nanoimprint lithography, in: Proceedings of SPIE 6517 2007, 65172B.; D.W. Johnson, H. Miller, M. Kubenz, F. Reuther, G. Grützner, Nanoimprinting with SU-8 Epoxy Resists, in: Proceedings of SPIE 6517 2007, 65172A.].The material system chosen is based on a blend of epoxy resins and a photo acid generator. Such epoxy resists cure during the imprint step in combined thermal and UV nanoimprint lithography. Initiated by UV exposure the cationic polymerisation occurs at elevated temperature forming a polymer pattern with significantly increased thermal stability compared to the uncured system.Apart from the material development leading to mr-NIL 6000LT the correlations between the parameters imprint temperature, exposure time and post exposure hold time are investigated in this work. With the applied resin combination a T_g of ?15 °C is obtained. This enables the formation of solid films at room temperature after spin-coating and prebake and nevertheless imprint temperatures in the range of 45–50 °C, which is a distinct decrease compared to the 100–110 °C needed for the previously introduced mr-NIL 6000 [C. Schuster, M. Kubenz, F. Reuther, M. Fink, G. Grützner, mr-NIL 6000 – New epoxy-based curing resist for efficient processing in combined thermal and UV nanoimprint lithography, in: Proceedings of SPIE 6517 2007, 65172B.] or the 65–70 °C necessary for defect-free imprinting of the epoxy-based polymer described in [D.W. Johnson, H. Miller, M. Kubenz, F. Reuther, G. Grützner, Nanoimprinting with SU-8 Epoxy Resists, in: Proceedings of SPIE 6517 2007, 65172A.]. mr-NIL 6000LT exhibits good dimensional stability at 120 °C after curing during the imprint process. This is sufficient for an isothermal imprint process as well as subsequent processes, e.g. metallization or etching.     

Flow property measurements for nanoimprint simulation

Number of recent works report that viscoelastic properties of ultra-thin polymer film (below 100 nm) could drastically change from bulk values, deeply impacting nanoimprint process simulation. A good knowledge of thin resist film viscosity is thus needed, either for UV imprint, or thermal imprint. Nanoimprint lithography has been used to characterize sub 100 nm resist film flow properties above glass transition temperature. Specifically designed stamps have been manufactured to control silicon etched lines motion into the melt polymer. Adapted fluid modelling is proposed to calculate dynamic viscosity of thin polymer film for different temperatures from experimental data. Good agreements between ours results and literature were found.