Temperature and pH‐Dependent Swelling Behavior of Poly(N‐isopropylacrylamide) Copolymer Hydrogels and Their Use in Flow Control

Poly(N‐isopropylacrylamide) (PNIPAAm) copolymer gels with acidic and basic comonomers of various molar ratios were prepared by radical polymerization. The relationship between the swelling behavior of the gels and the copolymerization ratio was studied experimentally at different temperatures and in various pH value buffer solutions. The results of the experiments revealed that the transition temperatures of the PNIPAAm copolymer gels were changed in proportion to the monomer ratio used in copolymerization. The pH value of the buffer solution strongly affected the swelling ratio and some of the transition temperatures of the gels. The PNIPAAm copolymer gels were used in a chemo‐mechanical valve. The liquid flows directly through a gel actuator, which consists of a cylindrical actuator chamber filled with small particles of the sensitive cross‐linked polymer. The flow rate as well as the pressure drop was measured in dependence on the solvent properties. With the presented experimental arrangement it could be shown that sensitive polymers can be used for controlling the flow in dependence on temperature and pH.

pH‐Dependence of the pressure in a chemo‐mechanical valve.     

Weitergehende Reinigung von Abwässern der Chemischen Industrie mit Hilfe von Aktivkohle

Further treatment of waste water in the chemical industry by use of activated carbon . Biological treatment has proved to be no longer adequate for numerous waste water streams emitted by chemical plants. Some of the pollutants entrained by the waste water feature poor biodegradability, and certain compounds even have a detrimental effect on the microorganisms of the activate sludge. Adsorption by activated carbon is one of the potential methods for eliminating such substances. Explanations refer to the physical phenomena of the process. Adsorption may be performed prior to or after biological treatment. Commercial-scale plants use granular activated carbon and use an intermittent process (fixed bed) or a continuous process (countercurrent adsorber). Possibilities and aspects are exemplified by plants using this process. Operating results are presented. A recent development combines the biological and adsorptive treatment which is based on the continuous admission of powdered activated carbon into the activated-sludge basin. Results obtained in a demonstration plant will be discussed. Cost-effective application of this technology is, however, conditional upon reactivation of spent carbon.     

Mechanism of cathodic PtCl 6 2- reduction to platinum clusters on electrodes coated with polyvinylpyridinium films

The electrochemical reduction of PtCl ₆ ^2- /HCl to Pt⁰ is investigated on electrodes coated with anion exchange polymer films. The first step is the cathodic reduction to PtCl ₄ ^2- . Three possible routes for the reaction PtCl ₄ ^2- to Pt⁰ are discussed: (i) a second electrochemical step; (ii) PtCl ₄ ^2- disproportionation; (iii) reduction by cathodically produced H₂. It is demonstrated that route (i) is normally dominant. The Pt⁰ produced has a large surface area. Individual microparticles (clusters) can be conveniently formed. As expected from the electrochemical mechanism the Pt⁰ produced is located at the electrode-coating interface.     

Racemic lactones from butterfat: An advanced approach that includes stereodifferentiation

A new method was developed to obtain lactones from butterfat. The application of lipases and capillary gas-liquid chromatography with chiral phases for the separation of γ-lactone enantiomers resulted in elucidation of the racemic composition of γ-lactones from butterfat. The seasonal distribution of lactones in butterfat was determined.     

Composition,nutritional, and functional properties,and quality criteria of soy protein concentrates and soy protein isolates

The available commercial soy protein concentrates and soy protein isolates afford the food processor concentrated sources of protein with some interesting and varied functional properties. Each class of products is mild to bland in flavor and light in color. The concentrates contain at least 70% protein and the isolates 90%. The nutritional quality of the proteins is fair to good and can be excellent either by supplementation with 1.5% methionine or by appropriate blending with other sources of proteins. The concentrates provide the food manufacturer with products where a high protein content for unit of volume or wt is needed. The isolates are available for uses where the functional properties reside solely in the protein and the nonprotein components may interfere. The adaptability of the proteins to modification by controlled processing conditions has made it possible for the manufacturers to produce a diversity of products that should be of interest to practically all food formulators.     

γ‐ and δ‐tocopherols are more effective than α‐tocopherol on the autoxidation of a 10% rapeseed oil triacylglycerol‐in‐water emulsion with and without a radical initiator

The antioxidative effects of γ‐ and mainly δ‐tocopherol in a multiphase system were hardly considered up to now. The aim of this study was i) to assess the effects and ii) to follow the degradation of α‐, γ‐ and δ‐tocopherol in concentrations of 0.01%, 0.05%, 0.1% and 0.25% during the oxidation of a 10% purified rapeseed oil triacylglycerol‐in‐water emulsion at 40 °C in the dark for 15 wk in a system containing a low oxygen concentration. Oxidation experiments were performed weekly by assessing the formation of hydroperoxides and hexanal, and the stability of the tocopherols was determined using high‐performance liquid chromatography. Storage tests were conducted with and without the addition of 0.01% α, α′‐azoisobutyronitrile (AIBN), which is a known radical initiator. α‐Tocopherol increased the formation of hydroperoxides in both tests as well as the generation of hexanal when the radical initiator was added; furthermore it was the least stable. γ‐Tocopherol delayed the formation of hexanal and prolonged the stability of the emulsion in a dose‐dependant manner. δ‐Tocopherol was the most stable and also the most effective in delaying lipid oxidation in the emulsions. Each concentration that was tested reduced the rate of hydroperoxide and especially hexanal formation. Hexanal was only formed to a slight extent after 15 wk of oxidation in the test with AIBN and the lowest dose of 0.01% δ‐tocopherol. For all tocopherols, strong correlations were found between tocopherol stability and the extent of oxidation. Results suggest that i) mainly δ‐tocopherol, but also γ‐tocopherol even less pronounced, are very good antioxidants in order to stabilize and prolong the shelf life of oil‐in‐water emulsions, ii) the antioxidative effects were intensified with increasing amounts.     

Energy—size reduction laws for ultrasonic fragmentation

The energy requirement is a key criterion for the selection and use of a grinding process. Ultrasonic dispersion is extensively used to disperse submicron agglomerated powders in liquid suspensions. Suspensions of silica agglomerates were ground with solids concentration up to 50% by weight. The fragmentation or grinding rate is inversely proportional to suspension volume. Starting from a semiempirical expression that relates fragmentation rate to particle size, suspension volume and ultrasonic power, energy consumption laws for both eroding and non-eroding powders are developed. Experimental results supporting the energy consumption laws are given. Lower power input for ultrasonication favors efficient energy use. For eroding powders (e.g. silica, zirconia) the energy expenditure per unit powder mass (specific energy) by ultrasonic grinding is lower than that of conventional grinding techniques. In contrast, it is slightly higher than ball milling for non-eroding powders (e.g. titania).     

Zusammenhänge zwischen molekulargewicht und elutionsvolumen bei der gelchromatographie von verschiedenen polyestern

The gel chromatograms of the low-molecular linear polyesters of adipic acid and hexanediol, butanediol, dimethyl propanediol, propanediol, diethylene glycol, and ethylene glycol, as well as those of polyhexamethylenecarbonate give on plotting log M against the elution volume a number of parallel calibration curves. The chromatograms obtained from the polyesters can be interpreted by a common calibration curve, if the logarithm of the number of atom equivalents is plotted against the elution volume. The number of atom equivalents results from the number of carbon atoms in the molecules and the number of oxygen atoms in the chain, taking into account the increments for carbon = 1 and for oxygen = 0,6. This common calibration relation applies to polystyrene gels in the solvent and swelling agent tetrahydrofuran, but not to polyvinylacetate gels. The number of atom equivalents obtained for every elution volume can be converted to the molecular weight of the corresponding polyesters. This makes it possible to use the calibration curve prepared for one type of polyester for evaluating the gel chromatograms of the other aliphatic polyesters.     

Pheromones in white pine cone beetle,Conophthorus coniperda (schwarz) (Coleoptera: Scolytidae)

Female white pine cone beetles,Conophthorus coniperda, attacking second-year cones of eastern white pine,Pinus strobus L., produced a sex-specific pheromone that attracted conspecific males in laboratory bioassays and to field traps. Beetle response was enhanced by host monoterpenes. The female-produced compound was identified in volatiles collected on Porapak Q and in hindgut extracts as (+)-trans-pityol, (2R,5S)-(+)-2-(1-hydroxy-1-methylethyl)-5-methyltetrahydrofuran. Males and females produced and released the (E)-(-)-spiroacetal, (5S,7S)-(-)-7-methyl-1,6-dioxaspiro[4.5]decane, which was not an attractant for either sex, but acted as a repellent for males. Porapak Q-trapped volatiles from both sexes contained (+)-trans-pinocarveol and (-)-myrtenol. In addition, hindgut extracts of females containedtrans-verbenol, while males had pinocarvone and verbenone. Work in Georgia and Canada confirmed that the same isomers of pityol and spiroacetal are present in two distinct and widely separated populations ofC. coniperda.