2019 ◽  
Vol 55 (1) ◽  
pp. 134-141
Author(s):  
I. I. Vashlaev ◽  
A. G. Mikhailov ◽  
M. Yu. Kharitonova ◽  
M. L. Sviridova

Author(s):  
T. J. Beveridge

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.


2019 ◽  
Vol 7 ◽  
pp. 196-206
Author(s):  
E.V. Chernousenko ◽  
◽  
I.N. Vishnyakova ◽  
Yu.S. Kameneva ◽  
Yu.N. Neradovskiy ◽  
...  

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Robert Christie

Abstract This paper presents an overview of the general chemical principles underlying the structures, synthesis and technical performance of azo pigments, the dominant chemical class of industrial organic pigments in the yellow, orange, and red shade areas, both numerically and in terms of tonnage manufactured. A description of the most significant historical features in this group of pigments is provided, starting from the discovery of the chemistry on which azo colorants are based by Griess in the mid-nineteenth century, through the commercial introduction of the most important classical azo pigments in the early twentieth century, including products known as the Hansa Yellows, β-naphthol reds, including metal salt pigments, and the diarylide yellows and oranges, to the development in the 1950s and 1960s of two classes of azo pigments that exhibit high performance, disazo condensation pigments and benzimidazolone-based azo pigments. A feature that complicates the description of the chemical structures of azo pigments is that they exist in the solid state as the ketohydrazone rather than the hydroxyazo form, in which they have been traditionally been illustrated. Numerous structural studies conducted over the years on an extensive range of azo pigments have demonstrated this feature. In this text, they are referred to throughout as azo (hydrazone) pigments. Since a common synthetic procedure is used in the manufacture of virtually all azo (hydrazone) pigments, this is discussed in some detail, including practical aspects. The procedure brings together two organic components as the fundamental starting materials, a diazo component and a coupling component. An important reason for the dominance of azo (hydrazone) pigments is that they are highly cost-effective. The syntheses generally involve low cost, commodity organic starting materials and are carried out in water as the reaction solvent, which offers obvious economic and environmental advantages. The versatility of the approach means that an immense number of products may be prepared, so that they have been adapted structurally to meet the requirements of many applications. On an industrial scale, the processes are straightforward, making use of simple, multi-purpose chemical plant. Azo pigments may be produced in virtually quantitative yields and the processes are carried out at or below ambient temperatures, thus presenting low energy requirements. Finally, provided that careful control of the reaction conditions is maintained, azo pigments may be prepared directly by an aqueous precipitation process that can optimise physical form, with control of particle size distribution, crystalline structure, and surface character. The applications of azo pigments are outlined, with more detail reserved for subsequent papers on individual products.


RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17431-17436
Author(s):  
Ting Yu ◽  
Zheng-hua Qian ◽  
Lin Li ◽  
Xiao-ling Wu ◽  
Hui He ◽  
...  

Three new thorium-based MOFs based on 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (H4TCPB) were obtained under a similar reaction system (metal salt, ligand, solvent, and acid are the same).


1999 ◽  
Vol 23 (12) ◽  
pp. 702-703
Author(s):  
Zehra Altuntaş Bayιr ◽  
Esin Hamuryudan ◽  
Özer Bekaroğlu

New metallophthalocyanines (M = Cu, Zn, Ni or Co) substituted in peripheral positions with four 11-membered triaza macrocycles are prepared from 1,4,7-tris( p-tolylsulfonyl)-1,4,7-triazaheptane and 1,2-dibromo-4,5-bis(bromomethyl)benzene or the corresponding anhydrous metal salt [CuCN, Zn(02CMe)2, NiCl2 or CoCI2].


2011 ◽  
Vol 700 ◽  
pp. 145-149 ◽  
Author(s):  
Tadafumi Adschiri ◽  
S. Takami ◽  
K. Minami ◽  
T. Yamagata ◽  
K. Miyata ◽  
...  

Various composite materials have been developed, but in many cases problems arise due to the combined materials such as fabrication becoming difficult because of the significant increase in viscosity, and transparency of the polymer is sacrificed. These issues can be overcome by controlling the nanointerface; however, this is considered as a difficult task since nanoparticles (NPs) easily aggregate in polymer matrices because of their high surface energy. Organic functionalization of inorganic NPs is required to increase affinity between NPs and polymers. For fabricating multi-functional materials, we proposed a new method to synthesize organic modified NPs by using supercritical water. Because organic molecules and metal salt aqueous solutions are miscible in supercritical water and water molecules serve as acid/base catalysts for the reactions, hybrid organic/inorganic NPs can be synthesized under the supercritical condition. The hybrid NPs show high affinity for the organic solvent and the polymer matrix, which leads to the fabrication of these super hybrid NPs. How to release the heat from the devices is the bottle neck of developing the future power devices, and thus nanohybrid materials of polymer and ceramics are required to achieve both high thermal conductivity and easy thin film flexible fabrication, namely trade-off functions. Surface modification of the BN particles via supercritical hydrothermal synthesis improves the affinity between BN and the polymers. This increases the BN loading ratio in the polymers, thus resulting in high thermal conductivity. Transparent dispersion of high refractive index NPs, such as TiO2 and ZrO2, in the polymers is required to fabricate optical materials. By adjusting the affinity between NPs and the polymers, we could fabricate super hybrid nanomaterials, which have flexiblility and high refractive index and transparency.


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