Concentration of phenolic compounds in aqueous mate (Ilex paraguariensis A. St. Hil) extract through nanofiltration

In order to establish the parameters to obtain aqueous mate extract with the highest content of total phenolic compounds (TPC), the response surface methodology (RSM) was used. The extract obtained at 100 °C, within 3 min and with pH of 6.0 was submitted to nanofiltration to concentrate the phenolic compounds of mate (Ilex paraguariensis A. St. Hill). The total phenolic content values in the permeate and in the concentrate collected in different volumetric reduction factors (VRF) were different from those detected in the feed extract. The concentration of phenolic compounds increased when VRF was increased, reaching the highest retention index (R) of 0.99 when VRF was 4.0. The permeate and the concentrate obtained in VRF 4.0 were verified through HPLC. 4,5-dicaffeoylquinic acid and gallic acid showed retention index of 1.00 and 0.95, respectively, while 3,4-dihydroxybenzoic acid and chlorogenic acid reached 0.99 and 0.98, respectively.     

Electrochemical synthesis of thin CdS films

Thin cadmium sulfide (CdS) films have been electrochemically synthesized on metal substrates and the related photosensitive surface barrier structures have been obtained. The proposed method can be used in the technology of thin-film photoelectric converters with large areas.     

Association of Moebius syndrome and hypopituitarism due to a midline anomaly. A case report

A 14 year old patient had both Moebius anomalad with arthrogryposis and growth hormone deficiency due to a midline defect. This combination suggests an abnormality in the organization of the neural crest and homologous neural tube segment.     

Enzymatic peroxycarboxylic acid formation in a hollow-fibre membrane reactor: kinetics and mass transfer

Peroxycarboxylic acids were produced enzymatically in a hollow-fibre membrane reactor, using R. javanicus and C. antarctica lipase as the biocatalysts. The peroxycarboxylic acids are commercially used to synthesize epoxides from unsaturated olefins. Here, oleic acid was converted to 9,10-epoxy stearic acid. A mass-transfer model, similar to heterogeneous catalysis was applied to the enzymatic reaction in a membrane reactor. The model enables the evaluation of the most important factors limiting the conversion rate in the reactor and the effect of the membrane material on mass transfer. It was found that the conversion is diffusion limited at a high concentration of the organic substrate. To illustrate the versatility of the model, it was applied to two situations performed under completely different circumstances.     

Behaviour of coal mineral matter in sintering and slagging of ash during the gasification process

The mineral matter in typical feed coals used in South African gasification processes and the ash derived from gasifying such coals have been investigated using a variety of mineralogical, chemical and electron microscope techniques. The mineral matter in the feed coals consists mainly of kaolinite, with minor proportions of quartz, illite, dolomite, calcite and pyrite plus traces of rutile and phosphate minerals. The calcite and dolomite occur in veins within the vitrinite macerals, and are concentrated in the floats fraction after density separation. Some Ca and Ti also appear to be present as inorganic elements associated with the organic matter.Electron microscope studies show that the gasification ash is typically made up of partly altered fragments of non-coal rock, bonded together by a slag-like material containing anorthite and mullite crystals and iron oxide particles, with interstitial vesicular glass of calcic to iron-rich composition. Ash formation and characteristics thus appear to be controlled by reactions at the particle scale, allowing the different types of particles within the feed coal to interact with each other in a manner controlled mainly by the modes of mineral occurrence. Integration of such techniques provides an improved basis for evaluating ash-forming processes, based on quantitative phase identification, bulk and particle chemistry, and the geometric forms in which the different phases occur.     

Effect of Silicon on the Desulfurization of Al-Killed Steels: Part II. Experimental Results and Plant Trials

Recent observations suggest that increased silicon levels improve ladle desulfurization of aluminum-killed steel. A kinetic model was developed and presented in part I of this paper, demonstrating that increased silicon levels in steel suppress the consumption of aluminum by parasitic reactions like silica reduction and FeO/MnO reduction, thus making more aluminum available at the interface for desulfurization. The results are increases in the rate and the extent of desulfurization. Predictions were compared with laboratory induction furnace melts using 1 kg of steel and 0.1 kg slag. The experimental results demonstrate the beneficial effect of silicon on the desulfurization reaction and that alumina can be reduced out of the slag and aluminum picked up by the steel, if the silicon content in the steel is high enough. The experimental results are in close agreement with the model predictions. Plant trials also show that with increased silicon content, both the rate and extent of desulfurization increase; incorporating silicon early into the ladle desulfurization process leads to considerable savings in aluminum consumption.     

A specific effect of alkali-metal iodides and thiocyanates on the viscosity of solutions of poly(methacrylic acid) in methanol

The solution properties of poly(methacrylic acid) (PMA) in methanol are specifically affected by thiocyanates and iodides of alkali metals. The relative decrease in the reduced specific viscosity of PMA in dilute methanolic solutions due to KSCN depends only on the ratio of concentrations of polymer and salt, and is independent of temperature and polymer molecular weight. With copolymers of methacrylic acid and 2-hydroxyethyl methacrylate, the effect is weaker.     

A Temperature Control System for Small Biological Preparations, Displaying Relatively Fast Heating and Cooling Capability

An apparatus is described with which it is possible to warm and cool the main duct of rabbit submaxillary gland in 10cc Ringer solution between 0°C and 50°C. The apparatus can be used for any small biological preparations such as muscles, nerves, etc. The heating and cooling is performed by a peltier element together with its control unit. Temperature is measured with a Cu-Const. thermocouple-with the reference placed in melting ice. The absolute accuracy of the temperature is ±0.5°C but reproducibility is within 0.10C. Speed of warming up for a large temperature change (AT) is 0.8°C/s. Cooling is-stower, i.e., 0.4°C/s. For AT 5°C the speed of warming up is about 0.60°C/s and the cooling rate in this case varies between 0.5°C/s and 0.16°C/s depending upon starting temperature. Full details are given about the construction of the control unit and the perfusion chamber in which the main duct is mounted. Some modifications are discussed with which it is also possible to use the system for flat biological preparations. The use of the apparatus as a programmable temperature system or as a temperature function generator is also discussed.     

Kinetics and equilibria of the hydration of propene over a strong acid ion exchange resin as catalyst

The kinetics and equilibria of the direct hydration of propene over a strong acid ion exchange resin (C8P ex AKZO) were studied. The experiments were c