电-Fenton及类电-Fenton技术处理水中有机污染物

传统Fenton技术是一种广泛用于水体里有机污染物降解的高级氧化技术(advanced oxidation technologies, AOTs)。它利用Fenton试剂Fe²⁺与H₂O₂反应生成具有强氧化性的羟基自由基(^·OH),从而降解有机污染物。基于相似的机理,过渡金属离子(Fe²⁺、Co²⁺和Ag⁺等)也可与过硫酸盐反应生成氧化能力较强的硫酸根自由基(SO₄^·-),而被称之为类Fenton技术。传统Fenton技术存在Fe²⁺投加量多,产生的铁污泥多等缺点,因此,有学者将Fenton技术与电化学技术结合,使Fe²⁺在阴极得以持续再生,这就是广为关注的电-Fenton技术。同样地,类Fenton技术也遇到与传统Fenton技术相似的问题。借鉴电-Fenton技术的成功应用,基于硫酸根自由基的类电-Fenton技术应运而生。本文在介绍电-Fenton和类电-Fenton技术原理的基础上,概括了电-Fenton和类电-Fenton技术的主要类型及其改进方法,并就值得深入研究的问题和热点趋势进行了展望。     

一种高T_c超导薄膜边缘弱连接结

本文报道了一种高 T_c 超导薄膜边缘弱连接结的制备方法.边缘结的两层 YBa_2Cu_3O_(7-δ)(YBCO)超导薄膜的零电阻温度均大于80K,所形成的边缘结在78K 下呈现零电压超流,而当温度为70K 时,在36GHz 的微波辐照下观察到了明显的 Shapiro 台阶.文中对出现的台阶次数进行了讨论.     

Highly selective population of two excited states [2mm]in nonresonant two-photon absorption

A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse. In this paper, we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution. Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value. We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption, such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization.     

Experimental Investigation on Selective Excitation of Two-Pulse Coherent Anti-Stokes Raman Scattering

Selective excitation of coherent anti-Stokes Raman scattering from the benzene solution is achieved by adaptive pulse shaping based on genetic algorithm, and second harmonic generation frequency-resolved optical gating （SHG-FROG） technique is adopted to characterize the original and optimal laser pulses. The mechanism for two-pulse coherent mode-selective excitation of Raman scattering is experimentally investigated by modulating the pump pulse in the frequency domain, and it is indicated that two-pulse coherent mode-selective excitation of Raman scattering mainly depends on the effective frequency components of the pump pulse related to specific vibrational mode. The experimental results suggest that two-pulse CARS has good signal-to-background ratio and high sensitivity, and it has attractive potential applications in the complicated molecular system.     

清末奏折染色工艺的无损光谱分析

奏折是一类特殊的纸质文物，是反映皇家文化的物证，其造纸和染色工艺体现了当时的政治制度文化和社会发展水平。奏折的材质较为脆弱，此前对此类文物的研究大多聚焦文字内容、样式、政治意义和保护修复方面，对本体材料和工艺方面的分析则相对匮乏。采用多种原位无损技术，对一份清末重臣岑春煊的请安折的材质和染色工艺进行了系统分析。通过紫外荧光摄影和傅里叶变换红外光谱分析确认黄绫面装饰的花纹使用了丝制品勾织而成。超景深显微观察、拉曼光谱及X射线荧光光谱(XRF)等结果表明奏折是使用了矿物颜料雌黄对纸张进行染黄，所用颜料的颗粒感细腻，推测其染色工艺可能采用了刷染法。雌黄颜料相比黄檗等有机染料更为昂贵，其使用不仅赋予了奏折防蛀防水的能力，更反映了奏折在清朝政治文化中的重要性，这也是纸张染黄案例中的又一新发现。此外，还探索性地运用光纤荧光光谱对奏折上朱批的颜料进行了分析，发现红色字迹为朱砂做墨书写，与拉曼光谱和XRF的结果相符。对奏折这类纸质文物的本体材料和工艺进行探究，有助于了解清代造纸和染色的技术特点，为合理保护和修复此类文物提供科学依据。同时也探讨了光纤荧光光谱在纸质文物的颜料鉴定方面的适应性，进一步拓展了...