Bright field and dark field STEM‐IN‐SEM imaging of polymer systems

The microstructural analysis of polymer systems (e.g., polymers and their composites) has largely been conducted by transmission electron microscopy (TEM). However, hard materials (e.g., metals and ceramics) are better suited for TEM imaging because such materials can withstand the high energy electron beam generated in TEM instruments. Recently, scanning TEM in scanning electron microscopy (STEM‐IN‐SEM) has emerged as a viable alternative to TEM imaging of polymer systems. STEM‐IN‐SEM uses a versatile and user‐friendly SEM instrument for examining the microstructure of polymer systems. In this study, we outline our method for STEM‐IN‐SEM imaging and apply it to the imaging of various commercial and model polymer systems. Imaging results are evaluated on the basis of measured signal intensity, which compare favorably to microstructural analysis using more costly TEM and STEM instruments. Furthermore, these comparable signal intensities are achieved through STEM‐IN‐SEM imaging with specimens that are three times thicker than those required for conventional TEM imaging. In this respect, as compared to TEM, STEM‐IN‐SEM offers faster specimen preparation times coupled with easier usability and lower maintenance costs, which are all attractive attributes for efficient quality control measures in industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40851.     

The role of vinylsulphonyl reactive dyes in prevention of wool damage

Reactive dyes of the vinylsulphone and α-bromoacrylamido types inhibit wool fibre degradation during dyeing. The effect is proportional to the amount of dye applied, which may be explained in terms of set inhibition and modification of the cell membrane complex. Reactive dyes are capable of interfering with the fibre thiol-disulphide interchange reactions, as evidenced by a study of model thiol derivatives of vinylsulphone dyes. H.p.l.c. has been widely employed to separate and assist with identification of these thiol adducts. The role of the cell membrane complex has been clarified using reactive vinylsulphone fluorescent compounds as dye models and following fibre penetration using fluorescence microscopy.     

基于细乳化/溶剂蒸发法制备复合纳米色素

采用细乳化/溶剂蒸发（MESE）的方法,制备了溶剂型染料/聚甲基丙烯酸甲酯（PMMA）复合纳米色素。系统分析了不同实验参数,包括表面活性剂浓度、聚合物浓度、染料装载量及超声时间对所制备的染料/聚合物复合色素形态的影响。结合TEM、X射线光电子能谱（XPS）及元素分析,发现借助MESE法制备染料/PMMA复合色素纳米颗粒具备核壳异质的微观结构。借助紫外-可见分光光度计测试了溶剂型染料经包覆后在水油两相的迁移过程,其随着聚合物溶解所发生的动态变化证实了染料已封装于聚合物壳内。所制备的染料/聚合物复合纳米色素表现出优异的光学稳定性能、存储稳定性能及耐水牢度。     

New insights into dye chemistry and physics

A review of the academic dye research performed by the Port Sunlight group and its coworkers over the past 15 years is presented. The work is focused on three areas: (1) substrate structure; (2) dye interactions in aqueous solution and on substrates; (3) dye degradation and products. For substrates, a detailed model of the nanoenvironment experienced by chemicals within cellulose fibre is given, showing the different environments and remarkable mobility of absorbed chemicals. Advanced nuclear magnetic resonance diffusion measurements provide the complex pathways by which compounds find their way in and out of the fibre. For dye interaction, detailed theoretical and experimental studies are reported on three model dye systems, the anionic monoazo dye Orange II, the bisazo anionic dye CI Direct Blue 1, and cationic monoazo thiazolium dyes, providing a comprehensive picture of their structure. A quantitative mechanism of dye binding to cellulose is shown. Resonance Raman provides an effective forensic tool for dye identification, even from single fibres. The products and kinetics of Orange II dye degradation by one‐electron reduction in aqueous solution is given, with the identification of an indophenol dye end‐product. In cellulosic materials the reduction mechanism is similar to solution, when the higher microviscosity is accounted for. Hydrolysis of thiazolium dyes occurs at both aromatic rings of the dye but on different timescales. Measurement and calculations of the electronic structures of one‐electron‐reduced and ‐oxidised dyes are presented. The mechanism of photooxidation by sunlight of azo dyes in cotton is delineated.     

Factors Affecting Dye Transfer in Conventional Printing with Disperse Dyes

The conventional printing of polyester materials with disperse dyes and alginate thickeners has been studied. The factors governing dye transfer were investigated using isolated films of the thickener. Alginates block dye transfer completely. Special geometrical conditions in the thickener layer are postulated and substantiated to explain the printing process (G model, d/l ratio). A major factor is direct contact between dye and substrate. The geometrical model explains only some of the facts. At high concentrations of dye, structural changes (S effect), also reported by other authors, are observed in the alginate la yer. These changes make it easier for the dye to escape from inside the layer. Fixation accelerants are especially useful for demonstrating the S effect. The S concept is corroborated by kinetic observations and by the evidence of a system of channels inside the print film. Light microscopy, transmission electron microscopy and scanning electron microscopy were used to identify the film structures and localise the dye.     

Textile applications of photochromic dyes. Part 3: factors affecting the technical performance of textiles screen‐printed with commercial photochromic dyes

The technical performance of five selected commercial photochromic dyes applied by screen‐printing on textiles was evaluated using a colour measurement methodology that has previously been established and validated. The results of wash fastness assessments were distinctly unusual. With the selected spirooxazine dyes, the degree of photocoloration increased with initial washing and decreased with subsequent washings, while the naphthopyrans behaved more normally, showing a consistent marginal decrease in photocoloration with repeated washing. An explanation is proposed consistent with scanning electron microscopy examination of the binder film degradation and with the structural differences between the dye classes. The dyes in this application showed limited photostability. The incorporation of ultraviolet absorbers was found to increase photostability only to an extent specific to particular ultraviolet absorber/dye combinations. However, the presence of the ultraviolet absorber led to a consistent reduction in the degree of photocoloration of the dyes. In contrast, the incorporation of hindered amine light stabilisers significantly enhanced the photostability of the dyes, providing an increase in resistance to photodegradation of up to fivefold.     

New Fluorescent Nanoparticles for Ultrasensitive Detection of Nucleic Acids by Optical Methods

For decades the detection of nucleic acids and their interactions at low abundances has been a challenging task that has thus far been solved by enzymatic target amplification. In this work we aimed at developing efficient tools for amplification‐free nucleic acid detection, which resulted in the synthesis of new fluorescent nanoparticles. Here, the fluorescent nanoparticles were made by simple and inexpensive radical emulsion polymerization of butyl acrylate in the presence of fluorescent dyes and additional functionalization reagents. This provided ultra‐bright macrofluorophores of 9–84 nm mean diameter, modified with additional alkyne and amino groups for bioconjugation. By using click and NHS chemistries, the new nanoparticles were attached to target‐specific DNA probes that were used in fluorimetry and fluorescence microscopy. Overall, these fluorescent nanoparticles and their oligonucleotide derivatives have higher photostability, brighter fluorescence and hence dramatically lower limits of target detection than the individual organic dyes. These properties make them useful in approaches directed towards ultrasensitive detection of nucleic acids, in particular for imaging and in vitro diagnostics of DNA.     

Novel (Phenothiazinyl)Vinyl-Pyridinium Dyes and Their Potential Applications as Cellular Staining Agents

We report here the synthesis and structural characterization of novel cationic (phenothiazinyl)vinyl-pyridinium (PVP) dyes, together with optical (absorption/emission) properties and their potential applicability as fluorescent labels. Convective heating, ultrasound irradiation and mechanochemical synthesis were considered as alternative synthetic methodologies proficient for overcoming drawbacks such as long reaction time, nonsatisfactory yields or solvent requirements in the synthesis of novel dye (E)-1-(3-chloropropyl)-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium bromide 3d and its N-alkyl-2-methylpyridinium precursor 1c. The trans geometry of the newly synthesized (E)-4-(2-(7-bromo-10-ethyl-10H-phenothiazin-3-yl)vinyl)-1-methylpyridin-1-ium iodide 3b and (E)-1-methyl-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium tetrafluoroborate 3a′ was confirmed by single crystal X-ray diffraction. A negative solvatochromism of the dyes in polar solvents was highlighted by UV-Vis spectroscopy and explanatory insights were supported by molecular modeling which suggested a better stabilization of the lowest unoccupied molecular orbitals (LUMO). The photostability of the dye 3b was investigated by irradiation at 365 nm in different solvents, while the steady-state and time-resolved fluorescence properties of dye 3b and 3a′ in solid state were evaluated under one-photon excitation at 485 nm. The in vitro cytotoxicity of the new PVP dyes on B16-F10 melanoma cells was evaluated by WST-1 assay, while their intracellular localization was assessed by epi-fluorescence conventional microscopy imaging as well as one- and two-photon excited confocal fluorescence lifetime imaging microscopy (FLIM). PVP dyes displayed low cytotoxicity, good internalization inside melanoma cells and intense fluorescence emission inside the B16-F10 murine melanoma cells, making them suitable staining agents for imaging applications.     

Electron Tomography of Catalysts

Electron microscopy can be extended from a 2D to a 3D analysis tool by electron tomography using both traditional bright-field TEM and the more recent HAADF STEM. This allows high spatial resolution 3D analysis of catalysts in terms of structural defects, particle size distributions and overall homogeneity.     

Minimization of organic chemical load in direct dyes effluent using low cost adsorbents

The work is carried out to minimize the organic chemical load (unexhausted dye contents) in direct dyes effluent using low cost adsorbents. The studies are made with different direct dyes, i.e. Direct Red 28, Direct Yellow 12, Direct Orange 26 and Direct Blue 1 with various adsorbents. Three different bio/natural materials have been selected as adsorbents. These includes, Sugarcane bagasse pith (SB), Saw dust (SD)—the plant origin products, and Brick powder (BP)—a silica based material obtained from earth's crust on thermal heating. These substances are almost discarded waste products with the possibility of use as adsorbents. Experimental work for the dye removal from the effluent by activated charcoal (AC) has also been carried out and the results are compared with other adsorbents. The amount of unexhausted organic dye present in the effluent is measured as chemical oxygen demand (COD) before and after the treatment. Adsorbent Sugarcane bagasse pith shows good performance as compared to Saw dust and Brick powder. For understanding the behaviour of adsorbents Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) has also been carried out.     

Synthesis and Characterization of Amphiphilic Gd(III) Complexes: Gd‐DTPA‐BA

Magnetic resonance imaging (MRI) is widely used to identify different diseases. MRI contrast agents, used to enhance the MRI signal, have been studied extensively for precise diagnosis. Based on the advantages of macromolecular MRI contrast agents of higher contrast imaging ability and a longer cycle time, this article modified the most common micromolecular contrast agent (Gd‐diethylene triamine pentaacetic acid [DTPA]). 2 long saturated aliphatic chains were attached to both sides of DTPA. DTPA derivatives with 12, 14, and 16 carbon lengths were synthesized and chelated to Gd³⁺. 3 amphiphilic MRI contrast agents were obtained and their structures were characterized using mass spectrometry, ¹H NMR, and Fourier transform infrared. Furthermore, the surface tension of the compounds was measured, and liposomes were prepared by mixing the synthesized amphiphilic molecules with egg lecithin and cholesterol. The assembly behavior of the liposomes was studied using transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential measurements. TEM showed that the liposomes possessed bilayer vesicle structures. The liposome size distribution determined by DLS was from 10 to 1000 nm, and as the aliphatic chain length increased, the polydispersity index (PDI) and zeta potential increased. No obvious changes in the PDI and zeta potential of the liposomes were observed after 5 days at room temperature, suggesting that they possess good stability.     

Crystalline order of silver–gold nanocatalysts with hollow-core and alloyed-shell

This paper reports the internal structure of Ag–Au bimetallic nanoparticles with hollow interiors and alloyed shells, synthesized by chemical reduction of metallic precursor and subsequent galvanic replacement reaction. By taking advantage of advanced electron microscopy methods such as high-resolution transmission electron microscopy (HRTEM), scanning TEM (STEM), weak beam dark-field (WBDF) microscopy, X-ray energy dispersive spectroscopy (EDS) and nano-beam electron diffraction (NBD), sufficient and necessary evidences confirm the sacrificial role of silver nanoparticles as templates for the epitaxial deposition of gold-rich atomic layers.     

In situ transmission electron microscopy of solid-liquid phase transition of silica encapsulated bismuth nanoparticles

The solid-liquid phase transition of silica encapsulated bismuth nanoparticles was studied by in situ transmission electron microscopy (TEM). The nanoparticles were prepared by a two-step chemical synthesis process involving thermal decomposition of organometallic precursors for nucleating bismuth and a sol-gel process for growing silica. The microstructural and chemical analyses of the nanoparticles were performed using high-resolution TEM, Z-contrast imaging, focused ion beam milling, and X-ray energy dispersive spectroscopy. Solid-liquid-solid phase transitions of the nanoparticles were directly recorded by electron diffractions and TEM images. The silica encapsulation of the nanoparticles prevented agglomeration and allowed particles to preserve their original volume upon melting, which is desirable for applications of phase change nanoparticles with consistently repeatable thermal properties.     

Comparison of madder (Rubia tinctorum L.) and weld (Reseda luteola L.) total extracts and their individual dye compounds with regard to their dyeing behaviour,colour, and stability towards light

This paper reports on the colorimetric properties of natural dyes from madder and weld plants. For both crops, a comparison is made among several individual dye compounds and the total plant extracts. Dyeing properties, colour properties and colour stability have been studied. Insight has been gained into the role of the major dye compounds present in the plant. For madder as well as for weld, the use of the total plant extract is considered to be advantageous over the use of individual dye compounds in terms of solubility, colour tone and stability towards light, and non‐coloured components present in the plant extract are considered to be responsible for increasing the solubility and the stability of the dye compounds.     

Improving the dyeability of wool by treatment with chitosan

A study of pretreatment of wool fabrics with chitosan by a pad-dry method has been carried out. The pretreatment effectively eliminates differences in dyeing behaviour between damaged and undamaged wool fibres, with an increase in the rate of dye uptake and the exhaustion of acid and reactive dyes. Penetration of the fibre by dyes has been followed using fluorescence microscopy and the role of the chitosan coating in the dyeing process clarified. Similar colour fastness properties were obtained on both untreated and chitosan-treated wool fabrics. The chitosan coating on wool fabrics has been examined by scanning electron microscopy. Evidence for the presence of chitosan was sought using a colorimetric method. It is believed that an approximately uniform and adherent chitosan sheath is formed on individual wool fibres.     

Green-Emitting Rhodamine Dyes for Vital Labeling of Cell Organelles Using STED Super-Resolution Microscopy

Fluorescence microscopy reveals the localization, spatial distribution, and temporal dynamics of the specifically labeled organelles in living cells. Labeling with exogenous conjugates prepared from fluorescent dyes and small molecules (ligands) is an attractive alternative to the use of fluorescent proteins, but proved to be challenging due to insufficient cell-permeability of the probes, unspecific staining, or low dye brightness. We evaluated four green-emitting rhodamine dyes and their conjugates intended for the specific labeling of lysosomes, mitochondria, tubulin, and actin in living cells. The imaging performance of the probes in living human fibroblasts has been studied by using confocal and stimulated emission depletion (STED) super-resolution microscopy with a commercial 595 nm STED laser. Two bright and photostable dyes (LIVE 510 and LIVE 515) provide specific and versatile staining.     

草酸青霉Penicillium oxalicum菌体吸附活性染料的性能及微观过程

研究了草酸青霉(Penicillium oxalicum)在模拟染料废水中以边生长边吸附的方式对活性翠蓝KN-G, M-GB, K-GL,活性黑K-BR、活性艳蓝M-BR、活性红紫K-3R和活性深蓝K-R 7种水溶性活性染料的脱色性能及吸附过程. 结果显示,生长菌体对7种活性染料具有良好的脱色性能,染料初始浓度为200 mg/L时,平均脱色率可达93.0%;染料初始浓度为400 mg/L时,活性翠蓝KN-G和M-GB的脱色率仍达到了99.7%和99.9%. 上清液的紫外光谱图及染料分子中铜离子浓度的检测结果表明,染料通过吸附方式从废水中去除. 通过SEM, TEM观察发现,生长菌体在吸附过程中,菌丝发生肿胀膨大,细胞壁发生结构重组,厚度增加10~15倍. 细胞壁的结构变化是生长菌体吸附染料的重要机制,为染料吸附提供位点和进入细胞内部的通道.     

Identification of Ti incorporation into β-SiAlON crystal structure through transmission electron microscopy techniques

In this paper, we report the transmission electron microscopy (TEM) observations on the incorporation of Ti transition metal element into β-SiAlON crystal structure in a bulk β-SiAlON–TiN composite material. Considering our energy dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopy results acquired by using nanometre-scale focused electron probe in scanning transmission electron microscopy (STEM) mode, the Ti-K characteristic X-ray lines and Ti-L_3,2 edges were detected in the chemical composition of the β-SiAlON grains. These results clearly reveal that Ti can enter into the β-SiAlON crystal structure. It is anticipated that this data will provide the new engineering insights on the production of transition metal element doped SiAlON-based materials for different applications.     

A novel synthesis method of hierarchical mesoporous MgO nanoflakes employing carbon nanoparticles as the hard templates for photocatalytic degradation

We describe a novel synthesis method for the preparation of bimodal mesoporous MgO nanoflakes and their application in photocatalytic activity for the degradation of methylene blue dye under UV light irradiation. For this purpose, Mg(OH)₂/carbon nanocomposite was obtained through the precipitation of magnesium hydroxide in the presence of carbon nanoparticles. X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), and transition electron microscopy (TEM) micrographs have shown that this strategy could be successfully used to prepare bimodal mesoporous MgO nanoflakes with two different pore size distributions centered at 3 and 25 nm and a high specific surface area of 216.9 m²/g. Furthermore, the product was used as an adsorbent to remove methylene blue dye from aqueous media. The results confirmed that the photocatalytic activity of the synthesized mesoporous MgO was significantly improved due to the presence of such different pore sizes and high specific surface area resulting in higher adsorption, storage, and degradation of dye molecules.