Microsampling and Determination of Metals in Iron Gall Ink

Abstract

Iron gall ink contains transition metals such as Fe, Cu, and Mn which are known to catalyze chemical reactions in support materials such as paper and parchment, which eventually leads to their deterioration over time. Identification of metals in ink can be an important step prior to the conservation treatment of a written document. In this work, syringe needles (16G–23G) were used to sample micro-cores (～0.7 mm in diameter) of ink and paper prior to analysis. Metals were extracted from the micro-core with HNO₃, prior to analysis using graphite furnace atomic absorption spectroscopy (GFAAS).     

Identifying a dot-matrix hologram by checking the intersecting angles of its gratings

Three features about the intersecting state of two gratings are used to identify dot-matrix holograms created by two-beam writers in this paper. The first feature is the intersection angle of the fringes of two gratings. The second feature is the ratio of the pitches of two lowest-order moiré-patterns formed by overlapping two gratings. The third feature is the length ratio of the two diagonal lines of a parallelogram constructed by two neighboring fringes of a first grating and two neighboring fringes of a second grating. All the three features are equivalent, i.e. they are all relative to the intersection angle of two gratings. Because the grating orientations of grating dots cannot be accurately reproduced for the orientation uncertainties of the components used by a two-beam writer, the intersection angles of the gratings of grating dots cannot be easily counterfeited. Therefore, the proposed methods are practical and feasible for the anti-counterfeiting applications of dot-matrix holograms.     

蓝色圆珠笔油墨紫外光照射变化的研究

在紫外光照射下，通过对蓝色圆珠笔字迹色痕ＦＴ－ＩＲ显微光谱的研究。发现溶剂挥发迅速。其次是环氧树脂的聚合、交联；三苯甲烷染料的分解比较缓慢；而醇酸树脂相对稳定。该研究为字迹色痕的进一步分辨提供了新方法，同时为字迹色痕的“年龄”推断奠定了基础。选用相关峰的相对峰高比来描述这一变化，并进行曲线拟合，消除了因笔力不同而引起的油墨流出量不同造成的误差，这在实际工作中是很有意义的。     

毛细管电泳法基于Fe(Ⅱ)与Fe(Ⅲ)的比值识别签字笔字迹的相对书写时间

可疑文件中墨水笔迹的相对时间鉴定对法庭科学、刑事案件的侦破和历史文献的整理都具有重要意义。该文建立了一种识别墨迹相对年代的毛细管电泳（CE）新方法。采用络合剂邻菲罗啉（1,10-phen）和反式-1,2-环己二胺四乙酸（CDTA）分别与Fe（Ⅱ）和Fe（Ⅲ）络合,然后用CE测定Fe（Ⅱ）和Fe（Ⅲ）的峰面积,通过比较从可疑笔迹中提取的Fe（Ⅱ）和Fe（Ⅲ）的峰面积比与从整个文档中提取出的Fe（Ⅱ）和Fe（Ⅲ）的峰面积比,判断整篇文字是否同时书写。实验首先对两种络合剂与两种价态铁离子的特异性络合进行了研究,结果表明1,10-phen与Fe（Ⅱ）、CDTA与Fe（Ⅲ）具有特异性络合。初步研究还表明：由于商用墨水pH值较低,墨水中的Fe（Ⅱ）在墨水瓶中比较稳定,因此Fe（Ⅱ）在墨水瓶中的氧化可以忽略不计;但当墨水书写在纸张上时,墨水中的硫酸会逐渐被纸张的纤维素所消耗,从而导致Fe（Ⅱ）在纸张中被逐渐氧化;在老化过程中Fe（Ⅱ）和Fe（Ⅲ）的峰面积比发生了变化,书写的时间越长,Fe（Ⅱ）和Fe（Ⅲ）的峰面积比就越小。该技术的成功应用依赖于找到一种合适的提取笔迹墨水的方法和CE分离测定Fe（Ⅱ）和Fe（Ⅲ）的方法。样品前处理程序如下：剪取1 cm长的墨水迹线,剪碎后放入2 mL的EP管中,加入0.5 mL 5 mmol/L的1,10-phen萃取1 min,再加入0.5 mL 20 mmol/L的CDTA振荡10 min,10000 r/min离心15 min,取上清液进行CE分离检测。CE条件如下：熔融石英毛细管（40.2 cm（有效长度30 cm）×75 μm i.d.）,100 mmol/L硼酸-硼砂缓冲溶液（pH 9.2）,压力上样（1.379 kPa,上样时间5 s）,分离电压20 kV,检测波长254 nm,温度控制在25℃。最后,对两种不同的墨水进行了测定,以评价所建方法的适用性,结果表明所建方法对于鉴别可疑文件中真伪笔迹的相对年代具有重要的指导意义。     

The Synthesis of 1-Ethyl-1＇-（4-vinylbenzyl）-4, 4＇-bipyridinium Chloride and Iodide and its Electrochromic Property

Abstract： A new compound 1-ethyl-1＇-（4-vinylbenzyl）-4, 4＇-bipyridinium chloride and iodide has been synthesized. The cyclic voltammogram and impedance spectra indicated that a layer of viologen＇s electrochromic （EC） film could be deposited on conductive ITO glass working electrode With polyelectrolyte as ionic conduction layer, solid EC devices based on this compound have been assembled and their thickness was about 2.35 mm. When different voltages were added, they showed blue or violet red color. After optimization, its response time was less than 50 ms, the number of redox circulation was over 107 and the color of coloration states could be kept for 3 days. This kind of EC device can meet the demand of electronic ink.     

A promising approach to conductive patterns with high efficiency for flexible electronics

A promising approach for conductive patterns with high efficiency for flexible electronics was developed by direct-writing, silver(I) solution (silver nitrate, acetate silver, etc.) with no solid particles as a conductive ink, conductive pen as a writing implement, and polyimide (PI) film as a substrate. The physical properties of the conductive ink were investigated by a dynamic contact angle system, ubbelohde viscometer and surface tension instrument. Conductive properties of silver ink film were investigated by 4-point probe, scanning electron microscope (SEM) and surface profilometer. It is demonstrated how the design of solvent composition in conductive ink affects surface morphology, and conductivity of silver ink films. It can be obtained that conductive patterns drawn on PI substrate not only have good mechanical/electrical fatigue properties, but also have low resistivity. Especially, when the sintering condition is 200 °C for 60 min, the resistivity can be down to 6.6 μΩ cm, 4.25 times the silver bulk resistivity.     

掺Gd3+的LiYF4∶Yb3+/Ho3+微米晶体制备以及在防伪中的应用研究

研究一种具有良好上转换发光性能的稀土掺杂发光材料,对于防伪技术领域具有非常重要的意义。为了改善LiYF₄∶Yb3+/Ho3+微米晶体的上转换发光性能,采用水热合成法成功制备了一系列Gd3+掺杂的LiYF₄∶Yb3+/Ho3+微米晶体,并采用X射线衍射(XRD)和扫描电子显微镜(SEM)对样品的相纯度和晶体形貌尺寸进行表征;在980 nm激光激发下,通过荧光光谱测试对LiGd_xY_1-xF₄∶Yb3+/Ho3+微米晶体的上转换发光性能进行分析。首先,研究了LiGd_xY_1-xF₄∶Yb3+/Ho3+微米晶体的晶体结构、尺寸、形貌和上转换发光性能的影响。结果显示,LiGd_xY_1-xF₄∶Yb3+/Ho3+微米晶体样品的XRD衍射峰与四方相的LiYF₄标准卡（PDF#17-0874）特征峰的位置完全对应且没有其他杂峰,SEM实验结果显示晶体形貌为八面体形状,表明成功合成了纯四方相的LiGd_xY_1-xF₄∶Yb3+/Ho3+微米晶体;荧光光谱测试结果显示,样品的上转换发光强度随着Gd3+掺杂比例的升高呈现出先增强后减弱的趋势,并且在Gd3+掺杂浓度为30 mol%时达到最强。其次,进一步研究了Gd3+掺杂浓度30 mol%样品的上转换发光性能与激发功率之间的关系,激发功率为0.5~1.5 W。LiGd_0.3Y_0.49F₄∶Yb3+/Ho3+微米晶体的红色和绿色上转换发光强度之比(R/G)随着激发功率的增加只发生大约12%的变化,样品的上转换发光并没有因为激发功率的增加而发生明显的变色,仍然可以发出稳定明亮的绿色光。这一现象表明,Gd3+的掺入很好地改善了样品的上转换发光性能,这种稳定高效的发光性能保证了其良好的防伪性能。最后,将Gd3+掺杂浓度为30 mol%的LiYF₄∶Yb3+/Ho3+微米晶体粉末与丝网金属油墨按照一定比例混合制成丝网防伪油墨,通过丝网印刷技术在玻璃基底上印制了“西安”字样的防伪标识图案,经过干燥处理后在980 nm激光的激发下,发出明亮且稳定的绿色可见光,制成的防伪标识图案具有发光强度高、易于识别、不易脱落的特点,可被广泛应用于防伪领域。     

Preparation and Characterization of Poly(Methyl Methacrylate) Coated TiO2 Nanoparticles

Titanium dioxide (TiO₂) nanoparticles were modified with poly(methyl methacrylate) (PMMA) to improve the dispersion stability of the nanoparticles in a dielectric medium and to reduce the density mismatch between TiO₂ and a dielectric medium for a microcapsule‐type electrophoretic display application. Nanoparticles were coated with PMMA by in situ dispersion polymerization. The PMMA‐coated TiO₂ nanoparticles were characterized by fourier transform‐infrared spectrometrey (FT‐IR), electrophoretic light scattering (ELS), and scanning electron microscopy (SEM). Density of PMMA‐coated TiO₂ nanoparticles was found to be dependent on the thickness of the PMMA coating on the nanoparticles. An increase of thermal stability of the PMMA layer and the contents of PMMA on the surface of the nanoparticles were measured via thermogravimetric analysis (TGA).     

Environmentally friendly electroless plating for Ag/TiO2-coated core–shell magnetic particles using ultrasonic treatment

In this work, high-reflectance brilliant white color magnetic microspheres comprising a Fe/TiO₂/Ag core–shell structure with a continuous, uniform compact silver layer were successfully fabricated by TiO₂-assisted electroless plating in a simple and eco-friendly method. The coating procedure for TiO₂ and Ag involved a sol–gel reaction and electroless plating with ultrasound treatment. The electroless plating step was carried out in an eco-friendly manner in a single process without environmentally toxic additives. The TiO₂ layer was used as a modification layer between the Fe microspheres and the silver layer to improve adhesion. A continuous and compact silver layer could be formed with a high degree of morphological control by introducing ultrasonication and adjusting the ammonium hydroxide concentration.     

3D printing of conjugated polymers

Three‐dimensional (3D) printing brings exciting prospects to the realm of conjugated polymers (CPs) and organic electronics through vastly enhanced design flexibility, structural complexity, and environmental sustainability. However, the use of 3D printing for CPs is still in its infancy and remains full of challenges. In this review, we highlight recent studies that demonstrate proof‐of‐concept strategies to mitigate some of these problems. Two general additive manufacturing approaches are featured: direct ink writing and vat photopolymerization. We conclude with an outlook for this thriving field of research and draw attention to the new possibilities that 3D printing can bring to CPs. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1592–1605