Assessment of the Influence of the Selected Range of Visible Light Radiation on the Durability of the Gel with Ascorbic Acid and Its Derivative

(1) Background: Depending on the type of hydrophilic polymer used, different types of hydrogels may be chemically stable or may degrade and eventually disintegrate, or dissolve upon exposure to sunlight. Many over-the-counter medications are now stored with a limited control of temperature, humidity and lighting. Therefore, in this study, the photostability of a gel made of cross-linked polyacrylic acid (PA), methylcellulose (MC) and aristoflex (AV) was assessed, and the interaction between the polymers used and ascorbic acid and its ethylated derivative was investigated. (2) Methods: The samples were continuously irradiated at constant temperature for six hours. The stability of the substance incorporated into the gels was assessed using a UV-Vis spectrophotometer. FTIR-ATR infrared spectroscopy was used to measure changes during the exposure. (3) Results: Ascorbic acid completely decomposed between the first and second hours of illumination in all samples. The exception is the preparation based on polyacrylic acid with glycerol, in which the decomposition of ascorbic acid slowed down significantly. After six hours of irradiation, the ethylated ascorbic acid derivative decomposed in about 5% for the polyacrylic acid-based gels and aristoflex, and in the methylcellulose gel it decomposed to about 2%. In the case of ascorbic acid, the most stable formulation was a gel based on polyacrylic acid and polyacrylic acid with glycerol, and in the case of the ethyl derivative, a gel based on methylcellulose. (4) Conclusions: The experiment showed significant differences in the decomposition rate of both compounds, resulting from their photostability and the polymer used in the hydrogel.     

Set up of a Screen-Printing Procedure for the Production of a β Alumina-Based Gas Sensor*

A gas sensor based on a -alumina thick film was recently developed on a laboratory scale. This sensor can be successfully used for selective detection of CO and NO_x, resulting from an appropriate choice of the working temperature of the sensing element. This paper deals with the approach of the industrial transfer of the sensor prototype, mainly concerning the scale-up of the screen-printing procedure from a hand-operated apparatus to an industrial production machine. Many parameters were already investigated during the laboratory development, namely the ink composition in terms of organic/inorganic component ratio, the type and amount of the liquid dispersant and rheological agent, the composition and softening temperature of the binder, the -alumina/binder weight ratio. During the industrial transfer, some other parameters must be considered, such as the particle size distribution of the ceramic components of the ink, the influence of the mesh number of the screen fabric on the surface texture of the -alumina film, the viscosity performances of the ink as a function of the applied shear rate and ageing. A common commercial metallic paste was also used as reference for optimizing the characteristics of the -alumina based ink.     

Portable erythema meter and its application to use in human skin

In this study a compact, hand-held, solid state erythema meter using light emitting diodes is described. This device has been constructed and used to compare with visual assessments of ultraviolet radiation in human subjects. A statistically significant correlation was obtained between erythema index and visual assessment in 24 ultraviolet irradiated subjects. Furthermore, the effects of three aftersun treatments have also been assessed objectively using the meter and subjectively using visual assessments. The ultraviolet-irradiated areas were less red following treatment than the irradiated and untreated areas. The results obtained by the meter were similar to and statistically significant with those obtained by visual assessment.
It is concluded that widespread use of an erythema meter such as that described would greatly improve all cutaneous erythema assessments.     

离子准分子研究的进展

到目前为止,已观察到许多碱金属卤化物离子准分子(AX)+、稀有气体碱金属离子准分子(RgA)+、稀有气体卤化物离子准分子(RgX)+、同核和异核稀有气体离子准分子的荧光谱以及Cs2+F-离子准分子的光学增益现象和Ar的离子准分子激光振荡现象.从光谱学和动力学的角度描述这些离子准分子研究的进展,并指出快速、高强度、大体积和均匀泵浦是实现离子准分子布居反转的关键所在.     

一种用于液晶分子取向排列的紫外光聚合物PV4研究

研究了紫外光聚合物材料ＰＶ４的化学性质;采用偏光显微照相技术,研究厂这种材料膜对液晶ＬＣ－６７１０Ａ的取向能力;用原子力显微镜（ＡＦＭ）,研究了光聚合前后聚合物取向膜微观形貌的变化;测最了这种材料引起的液晶预倾角、单面光控取向层扭曲向列液晶显示器件（ＴＮ－ＬＣＤ）的电光特性和时间响应特性;分析了液晶分子取向排列的机理。     

Flexible thin-film transistors using multistep UV nanoimprint lithography

A multistep imprinting process is presented for the fabrication of a bottom-contact, bottom-gate thin-film transistor (TFT) on poly(ethylene naphthalate) (PEN) foil by patterning all layers of the metal–insulator–metal stack by UV nanoimprint lithography (UV NIL). The flexible TFTs were fabricated on a planarization layer, patterned in a novel way by UV NIL, on a foil reversibly glued to a Si carrier. This planarization step enhances the dimensional stability and flatness of the foil and thus results in a thinner and more homogeneous residual layer. The fabricated TFTs have been electrically characterized as demonstrators of the here developed fully UV NIL-based patterning process on PEN foil, and compared to TFTs made on Si with the same process. TFTs with channel lengths from 5 μm down to 250 nm have been fabricated on Si and PEN foil, showing channel length-dependent charge carrier mobilities, μ, in the range of 0.06–0.92 cm² V⁻¹ s⁻¹ on Si and of 0.16–0.56 cm² V⁻¹ s⁻¹ on PEN foil.     

Highly Efficient Deep‐Blue Electrophosphorescent Pt(II) Compounds with Non‐Distorted Flat Geometry: Tetradentate versus Macrocyclic Chelate Ligands

A new class of deep blue electrophosphorescent Pt(II) emitters have been designed and synthesized. This new class of deep blue Pt(II) emitters employ tetradentate and macrocyclic chelate chromophores to constrain the Pt(II) molecules in a non‐distorted flat geometry in both the ground state and the excited state. The new deep blue emitters do not produce excimer emission, with emission quantum efficiency as high as 95% in 10% doped PMMA (poly(methyl methacrylate) films, and excellent UV stability, compared to the corresponding bidentate Pt(II) emitters. The macrocyclic tetradentate chelate Pt(II) compounds are the first examples of fully sterically constrained deep blue Pt(II) emitters that do not display structural distortion and have a higher thermal stability and a higher emission quantum efficiency than the corresponding non‐macrocyclic tetradentate Pt(II) analogues. A computational study supports that the macrocylic Pt(II) compounds are structurally more stable than the tetradentate Pt(II) molecules. Bright and efficient deep blue electrophosphorescent devices using a macrocyclic Pt(II) emitter have been successfully fabricated with a maximum brightness of 10 680 cd m^?2, maximum external quantum efficiency of 15.4% (at 490 cd m^?2), and Commission Internationale de L'Eclairage (1931) coordinates (x + y ) of less than or near 0.30, respectively.     

丁二酸改性电子墨水用球形SiO2颗粒的FTIR及XPS分析

采用丁二酸对球状亚微米级SiO2颗粒进行表面改性,以提高SiO2颗粒于四氯乙烯溶剂中的电泳性能,制备适于电子墨水用的白色电泳颗粒。利用傅立叶红外光谱(FTIR)、X射线光电子谱(XPS)和Zeta电位粒度仪,研究了丁二酸改性SiO2颗粒的表面键合情况及其在四氯乙烯溶剂中的Zeta电位变化情况。研究发现,丁二酸仅有一端的羧基与SiO2颗粒表面的羟基发生酯化反应,而且当丁二酸的用量为3g(50mL乙腈中)时,接枝于SiO2颗粒表面的丁二酸的量达到最大值,此时C1s(O—CO)/Si(原子比)有最大值为5.77×10-2。Zeta电位测试结果表明,丁二酸改性后的SiO2颗粒在四氯乙烯中的Zeta电位比改性前的SiO2颗粒提高了约5.5倍。     

硅/玻璃紫外固化中间层键合

利用玻璃的透光特性和紫外固化的成熟技术,研究了一种使用紫外固化胶作为中间层的玻璃/硅室温键合工艺.通过选择一定波段的紫外固化胶,旋涂紫外胶后使用365nm光刻机作为紫外光源控制紫外固化,从而实现了硅/玻璃的中间层键合.分析测试结果表明,紫外固化辅助的中间层键合可以成功应用于硅/玻璃键合,中间层厚5～6μm,键合强度达到26MPa.该工艺只需室温条件,简单高效,成本低廉,无需额外的压力或电场,对于硅/玻璃低温键合封装具有潜在的应用价值.     

Ultraprecise 3D Printed Graphene Aerogel Microlattices on Tape for Micro Sensors and E-Skin

3D printed graphene aerogels hold promise for flexible sensing fields due to their flexibility, low density, conductivity, and piezo-resistivity. However, low printing accuracy/fidelity and stochastic porous networks have hindered both sensing performance and device miniaturization. Here, printable graphene oxide (GO) inks are formulated through modulating oxygen functional groups, which allows printing of self-standing 3D graphene oxide aerogel microlattice (GOAL) with an ultra-high printing resolution of 70 µm. The reduced GOAL (RGOAL) is then stuck onto the adhesive tape as a facile and large-scale strategy to adapt their functionalities into target applications. Benefiting from the printing resolution of 70 µm, RGOAL tape shows better performance and data readability when used as micro sensors and robot e-skin. By adjusting the molecular structure of GO, the research realizes regulation of rheological properties of GO hydrogel and the 3D printing of lightweight and ultra-precision RGOAL, improves the sensing accuracy of graphene aerogel electronic devices and realizes the device miniaturization, expanding the application of graphene aerogel devices to a broader field such as micro robots, which is beyond the reach of previous reports.