Gas barrier and morphology characteristics of linear low-density polyethylene and two different polypropylene films

In this research, linear low-density polyethylene (PE-LLD), cast polypropylene (PPcast), and bioriented coextruded polypropylene (BOPP) were used as polymeric materials. Permeability, diffusivity, and solubility of N₂, O₂, and CO₂ through above polymers were obtained at different temperatures. The structure and thermal–mechanical features of the films were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The permeability, diffusivity, solubility, and their temperature dependency were studied by correlations with gas molecule properties. The highest permeation coefficients (>3.8 × 10⁻⁸ cm³ cm⁻¹ s⁻¹ bar⁻¹) are obtained for PPcast at 60 °C. Activation energy for permeation follows the sequence: N₂ > O₂ > CO₂ for PE-LLD and PPcast. On the other hand, the diffusion activation energy follows the order: O₂ > CO₂ > N₂ and N₂ > CO₂ > O₂ for PE-LLD and PPcast, respectively. In the case of BOPP, activation energy follows the sequence: O₂ > CO₂ > N₂; CO₂ > N₂ > O₂; and O₂ > CO₂ > N₂ for permeation, diffusion, and heat of sorption, respectively.     

Proteins of the penicillin biosynthesis pathway

Two sequential steps are common to the biosynthesis of all penicillin-derived antibiotics: the reaction of three L-amino acids to give L-delta-(alpha-aminoadipoyl)-L-cysteinyl-D-valine, and the oxidation of this tripeptide to give isopenicillin N. Recent studies on the peptide synthetase and oxidase enzymes responsible for these steps have implications for the mechanisms and structures of related enzymes involved in a range of metabolic processes.     

Metastable solutions and interactions of decomposition products in porogen derived membranes

Small incompatible molecules formed on porogen decomposition were found to be metastably dissolved in Porogen Derived Membranes, confirming previous analysis. ¹Degrees of metastable dissolution are determined by polymer and porogen characteristics, by porogen content, and by decomposition parameters (characteristics of reagent, its concentration, and decomposition temperature). These parameters determine the characteristics of decomposition products (DPs) formed, the rate of their formation, and the properties of the matrix through which they have to diffuse for phase separation. Extraction experiments indicated that, for many compositions, leaching out of DPs during contact with water is very slow. Porogen derived membranes are thus intermediate between polymeric membranes and supported liquid membranes, with the potential of combining high selectivity and reasonable stability. © John Wiley & Sons, Inc.     

Quantitative histological studies on the lateral geniculate nucleus in the cat. III. Distribution of different types of neurons in the several layers of LGN

An attempt is made on the definition of proportional distribution of the different types of neurons in the layers of LGN by means of quantitative method. On the basis of nuclear volume, nuclear and cell diameters the different types of neurons were separated according to their size and shape. The ratio of relay and interneurons proved to be 2:1 in all layers of LGN of cat. The proportional distribution of further subgroups of neurons was also defined. The bilateral connections between the relay and interneurons based on initial axon collateral of TCR neurons and on axon terminals and dendritic appendages of INs, are also calculated. The interneurons--in the LGN--have widespread contacts with both types of relay neurons, similarly the relay neurons contact the interneurons. The numerical data of morphological observations are accord with the results of physiologists.     

Analyzing fuzzy risk based on a new fuzzy ranking method between generalized fuzzy numbers

In this paper, we present a new method for analyzing fuzzy risk based on a new method for ranking generalized fuzzy numbers. First, we present a new method for ranking generalized fuzzy numbers. It considers the areas on the positive side, the areas on the negative side and the heights of the generalized fuzzy numbers to evaluate ranking scores of the generalized fuzzy numbers. The proposed method can overcome the drawbacks of some existing methods for ranking generalized fuzzy numbers. Then, we apply the proposed method for ranking generalized fuzzy numbers to develop a new method for dealing with fuzzy risk analysis problems. The proposed method provides us with a useful way to deal with fuzzy risk analysis problems based on generalized fuzzy numbers.     

Redox-potential and browning of tomato paste in aluminium tubes during storage at different temperatures

The influence of temperature and applied lacquer on aluminium (Al) tubes on physico-chemical changes of tomato paste during storage was studied. Packaging and storage conditions have a considerable influence on both the oxidative changes in the product and corrosion behaviour of the Al tubes. The greatest changes during storage were the ascorbic acid and hydroxymethylfurfural contents; the compounds known to possess certain oxido-reduction power. The consequence of oxidation-reduction reactions taking place during storage was the establishment of particular redox values: the lower the reducing power of the compounds present, the higher the rH value obtained.

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Braunwerden und Redoxpotential des Tomatenkonzentrates bei verschiedenen Lagerungstemperaturen

Zusammenfassung Es wurden der Einfluß der Temperatur und der Alu-Verpackung auf physikalisch-chemische Änderungen des Tomatenkonzentrates während der Lagerung untersucht. Dabei wurde festgestellt, daß die Verpackung und die Lagerungsbedingungen auf die oxydativen Veränderungen des Tomatenkonzentrates und der Korrosionsprozeß in der Alu-Verpackung einen großen Einfluß haben. Die größte Änderungen während der Lagerung wurde im Gehalt an Askorbinsäure und Hydroxymethylfurfural festgestellt. Die genannten Verbindungen haben gewisse Redox-Eigenschaften. Die Redox-Reaktion während der Lagerung hat Einfluß auf die Veränderung des Redox-Potentials, und zwar ist dieses um so höher, je niedriger die Reduktionskraft der anwesenden Verbindungen ist.

     

Production of rhamnolipids-producing enzymes of <Emphasis Type="Italic">Pseudomonas</Emphasis> in <Emphasis Type="Italic">E. coli</Emphasis> and structural characterization

Rhamnolipids are a class of biosurfactants that have a great potential to be used in industries. Five proteins/enzymes, namely RhlA, RhlB, RhlC, RhlG and RhlI, are critical for the production of rhamnolipids in Pseudomonas aeruginosa. Four of the 5 proteins except RhlC were successfully over-expressed in E. coli and three of them (RhlA, RhlB and RhlI) were purified and obtained in milligram quantities. The purified proteins were shown to be folded in solution. Homology models were built for RhlA, RhlB and RhlI. These results lay a basis for further structural and functional characterization of these proteins in vitro to favor the construction of super strains for rhamnolipids production.

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Oxygen Interaction with Hexagonal OsB2 at High Temperature

The stability of ReB₂‐type hexagonal OsB₂ powder at high temperature with oxygen presence has been studied by thermogravimetric analysis, differential scanning calorimetry, SEM, EDS, and high‐temperature scanning transmission electron microscopy and XRD. Results of the study revealed that OsB₂ ceramics interact readily with oxygen present in reducing atmosphere, especially at high temperature and produces boric acid, which decomposes on the surface of the powder resulting in the formation of boron vacancies in the hexagonal OsB₂ lattice as well as changes in the stoichiometry of the compound. It was also found that under low oxygen partial pressure, sintering of OsB₂ powders occurred at a relatively low temperature (900°C). Hexagonal OsB₂ ceramic is prone to oxidation and it is very sensitive to oxygen partial pressures, especially at high temperatures.     

Camera for coherent diffractive imaging and holography with a soft-x-ray free-electron laser

We describe a camera to record coherent scattering patterns with a soft-x-ray free-electron laser (FEL). The camera consists of a laterally graded multilayer mirror, which reflects the diffraction pattern onto a CCD detector. The mirror acts as a bandpass filter for both the wavelength and the angle, which isolates the desired scattering pattern from nonsample scattering or incoherent emission from the sample. The mirror also solves the particular problem of the extreme intensity of the FEL pulses, which are focused to greater than 10(14) W/cm2. The strong undiffracted pulse passes through a hole in the mirror and propagates onto a beam dump at a distance behind the instrument rather than interacting with a beam stop placed near the CCD. The camera concept is extendable for the full range of the fundamental wavelength of the free electron laser in Hamburg (FLASH) FEL (i.e., between 6 and 60 nm) and into the water window. We have fabricated and tested various multilayer mirrors for wavelengths of 32, 16, 13.5, and 4.5 nm. At the shorter wavelengths mirror roughness must be minimized to reduce scattering from the mirror. We have recorded over 30,000 diffraction patterns at the FLASH FEL with no observable mirror damage or degradation of performance.