Coordination polymers of Zn(II) and N,N'-bis (carboxymethyl) dithiooxamide

Summary Coordination polymers were synthesized using N,N'-Bis (carboxymethyl) dithiooxamide (NN' CMDTO) and Zinc(II) salts. The complexes were characterized by elemental analyses, IR spectral studies, TGA and viscosity measurements. In the proposed structures the ligand was supposed to be coordinated to metal through sulphur and oxygen.     

Bücherschau

Ohne Zusammenfassung VDI     

Carbon Aerogels as Electrode Material in Supercapacitors

Due to their large specific surface area and their high electrical conductivity carbon aerogels are promising materials for electrodes in electrochemical double-layer capacitors (supercapacitor). The carbon aerogels were made via pyrolysis of resorcinol formaldehyde aerogels. The latter were prepared by supercritical and subcritical drying as well. The important findings of our investigation were, that the highest capacities of 46 F/cm³ were measured for samples with a density of about 800 kg/m³ pyrolyzed at 800°C. Also it was shown that RF-gels with molar resorcinol/catalyst ratios 1000 or higher can be dried subcritically without cracking or significant shrinkage. Carbon aerogels derived from these RF-aerogels have a small mesopore surface area, however an especially large micropore area. They provide electrical capacities which are most suitable for their use in supercapacitors.     

Hot slag resistance of refractories

Conclusions It is proposed to test refractories for hot-slag resistance by which is meant the complex property typifying the wear resistance of refractories with the single-sided action of high temperature and slags and subsequent sharp cooling.A laboratory gas-oxygen furnace design was developed for testing the slag resistance with one-sided heating with the aim of forming zones in the specimens.The spalling resistance of zonal magnesite-chromite and periclase-spinel goods was determined.According to the slag resistance and operating spalling resistance the periclase-spinel refractories are better than the spalling-resistant magnesite-chromite.     

Effect of the use of mineral filler on the properties of concrete

Engineers of the concrete technology are increasingly concerned with the material passing through a sieve of the size under 0.149 mm. Materials called very fine aggregate or mineral filler may affect the performance of concrete in an either positive or a negative way. Discussions on aggregate containing very fine material are vitally important. Washing the aggregate residue has been the sole way to solve this matter to date. This is mainly based on the debatable opinion that materials of this kind are regarded as clay material. The goal of the study was to determine how the content of mineral filler might affect properties of concrete. Two types of aggregates with different amounts of cement and mineral filler were used. Basically, mineral filler replaced sand. The effect of applying different amounts of mineral filler on concrete was then determined. The addition of 7-10% of mineral filler to fine aggregate (0-2 mm) was found to considerably improve the properties of concrete.     

Über das Spreiten von Lipiden auf der Haut

On the Spreading of Lipids on the Skin The spontaneous spreading of liquid lipids on human skin is an important property for the use value of such products in cosmetic and pharmaceutical preparations. A comparative evaluation procedure based on an impression method is described, by means of which it is possible to determine the spreading rates in a reproducible manner. The standardized spreading values of a number of lipids are discussed in comparison with their chemical structure and physico-chemical data such as viscosity and surface tension. None of these data series correlates entirely with the spreading rates of all the lipids tested. However, it is possible to assess relative spreading rates within similarly structured groups of compounds.     

Polarographic behaviour of diisopropylaminoethane thiol hydrochloride

The polarographic behaviour of diisopropylaminoethanethiol HCl (RSH) has been studied in presence of 0·1 M LiCl at the dme. The effects of pH, supporting electrolyte, concentration, drop time and temperature on the characteristics of the wave have been investigated. The curves consist of two waves—a small pre-wave followed by a normal anodic wave over the entire pH range (2·60–12·60). The maximum number of moles absorbed on unit area is 3·98 × 10^?10 mole/cm², ie 2·4 × 10¹⁴ molecules/cm², which corresponds to an area 41·6 Ų per adsorbed molecule. The adsorption coefficient and molar adsorption energy are 6·34 × 10² and 26·34 kcal/mole respectively. The electrode reaction is reversible, diffusion-controlled and involves a one-electron tranfer process. The pK of the ?SH group is 10·6. Controlled-potential electrolysis, interaction with mercuric chloride and mathematical analysis reveal the depolarization of mercury with the formation of a Hg(I) complex, mercurous mercaptide RSHg, which rapidly changes to more stable mercuric complex (RS)₂Hg.     

Structure and properties of polyimide‐bonded magnets processed from prepolymers based on diacetyl derivatives of aromatic diamines and dianhydrides

We report a novel method of polyimide (PI) synthesis from prepolymers based on dianhydrides and diacetyl derivatives of aromatic diamines that facilitate the preparation of a melt processable mixture at 300 ± 10°C of the prepolymer and magnetic Nd‐Fe‐B alloy to provide PI‐bonded magnets with enhanced properties. It is shown that chemical structure of the prepolymers strongly influences viscosity behavior via crystallization of the oligoimide in the melt, leading to formation of PI with rigid‐rod like structure. This structural ordering of the prepolymers based on diacetyl derivative of diamine used in this study, if not controlled, leads to exponential increase of melt viscosity with time, making it practically impossible to prepare melt processable mixture of the magnetic particles and the PI prepolymers at elevated temperatures. The results obtained demonstrate that appropriate dianhydrides and diacetyl derivatives of diamines that do not lead to crystallization of oligoimides in prepolymer mixture can be used under controlled processing conditions to prepare melt‐processable PI‐bonded magnets containing rigid‐rod like PI structure that significantly increases thermal stability of the magnets. The temperature dependencies of the magnetic properties of the PI‐bonded magnets under conditions that they are likely to encounter during their service life were found to be remarkably similar to that of commercial thermoplastic magnets such as injection‐molded nylon magnets. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 478–485, 2006     

Effect of structure controlled deposited layers on the retention of flavour compounds in reverse osmosis

Deposited layers are often negative phenomena of membrane processes. They reduce flux and elongate the time for concentration or separation. Electron micrographs made by other investigators have shown that the deposit is compact adjacent to the membrane and spongy on top. The compact layer is as homogeneous as the active layer of the membrane; therefore, it may have the same retention behaviour as the membrane.

Our objective has been to investigate the rejection behaviour of deposit layers in reverse osmosis. Membrane fouling was caused by whey proteins and skin milk proteins with or without additional heat treatment. After the forming of the deposited layer the rejection of apple juice flavour was determined and compared with an experiment without a deposited layer. The measurements show that the rejection could be influenced depending on the treatment of the layer.