Ciliary neurotrophic factor increases the survival of magnocellular vasopressin and oxytocin neurons in rat supraoptic nucleus in organotypic cultures.

Organotypic cultures of the rat hypothalamus are very useful models for the long-term study of parvocellular vasopressin (VP) neurons in the paraventricular (PVN) and suprachiasmatic (SCN) nuclei. However, they do not preserve significant numbers of VP magnocellular neurons (VP-MCNs) in either the PVN or the supraoptic nucleus (SON). Vutskits et al. [(1998) Neuroscience 87:571-582] reported that ciliary neurotrophic factor (CNTF) was a selective survival factor for rat VP-MCNs in organotypic cultures of the rat hypothalamic paraventricular nucleus (PVN). We examined the effects of CNTF on the survival of these neurons in rat and mouse SONs. CNTF (10 ng/ml) in the culture media increased the survival of VP-MCNs by 6-fold and OT-MCNs by 3-fold. In the mouse, both OT- and VP-MCNs survive very well in organotypic cultures under standard culture conditions and the addition of CNTF had no further effect. Consistent with these results, in situ hybridization showed substantially higher levels of VP- and OT-mRNA in rat PVNs and SONs in the presence of CNTF, but produced no changes in these nuclei in the mouse. The optimum period for the survival effect of CNTF on MCNs in the rat hypothalamic cultures was in the first 7-10 days of culture and this effect is maintained for at least 5 additional days if CNTF is then removed from the medium. Therefore, using CNTF in the culture media can provide an opportunity for long-term studies of rat VP- and OT-MCNs in SONs in organotypic cultures.     

Variation in fatty acid composition of ewes' milk during continuous transition from dry winter to natural pasture diet

The profile variations of approximately 70 fatty acids (FAs) in milk of ewes consuming total mixed rations (TMR) and grazing natural pasture were determined. Milk of ewes grazing pasture in May and September in the Slovak Republic contained 3-times more conjugated linoleic acid (CLA) (P < 0.001) and trans-vaccenic acid (TVA) (P < 0.001), and 2-times more α-linolenic acid (ALA) (P < 0.001) than that of ewes fed TMR. A doubling of the CLA and TVA contents of milk of ewes fed with TMR was achieved by changing to meadow hay containing a higher ALA content. Less availability of vegetation and lower ALA pasture content in summer (P < 0.001) caused a 2-fold decrease (P < 0.001) of CLA and TVA contents when compared with data obtained in May. With grass re-growth and an increase in pasture ALA content in September, the CLA and TVA contents rose to values similar to those obtained in May (P > 0.05). No significant differences in the FA composition in milk of ewes grazing on summer pasture at higher altitude were observed.     

Inulin-based emulsion-filled gel as a fat replacer in prebiotic- and PUFA-enriched dry fermented sausages

In order to produce fermented sausages with prebiotic fibre and improved fatty acid composition, 16% of pork back fat was replaced with inulin gelled suspension (I) and inulin linseed oil gelled emulsion (IO). Physico-chemical analysis, fatty acid profiles, lipid oxidation, microbiological, textural, colour and sensory analysis were carried out. The fat content was lower in I (31.38%) and IO (35.36%) modified sausages compared to control (44.37%) (P < 0.05). IO sausages had lower SFA and MUFA and higher PUFA content with an improved n-6/n-3 ratio (2.23) (P < 0.05) and α-linolenic acid increment (5.74 g per 100 g). Reformulation led to decrease in springiness, chewiness and hardness and increase in adhesiveness of the sausages. Modified sausages had lower L* and higher a* values, while b* values of I sausages did not differ compared to control sausages. Modified sausages were acceptable regarding all sensory attributes. Lipid oxidation parameters showed higher susceptibility to oxidation and lipolysis in IO sausages.     

Scapania nemorea liverwort extracts: Investigation on volatile compounds, in vitro antimicrobial activity and control of Saccharomyces cerevisiae in fruit juice

This study was focused on chemical characterisation of liverwort Scapania nemorea extracts and their antimicrobial activity against pathogenic and food-spoiling yeasts and bacteria. The chemical composition of three different extracts of the liverwort S. nemorea was determined by solid phase microextraction gas chromatography-mass spectrometry (SPME GC–MS). The dominant compounds in extracts were sesquiterpenes β-bazzanene (11%, 17.9% and 14.6%), isobazzanene (10.2%, 15.8% and 11.7%) and aromadendrene (8.8%, 12.9% and 10.6%) in the methanol, ethanol and ethyl acetate extracts, respectively. Antimicrobial potential of S. nemorea extracts against food spoiling yeasts and bacteria was determined in vitro by microdilution method. The Minimum Inhibitory Concentration (MIC) varied from 0.5 to 3 mg/mL for bacteria, and from 0.2 to 1 mg/mL for yeasts. Moreover, the combined effects of dry methanol extract of S. nemorea and heat processing on the survival and growth of a spoilage yeast in an apple/orange-based beverage, have been assessed through a Central Composite Design. Changes in color and flavor of the beverages were considered acceptable also after one week of storage at 25 °C. The results provide evidence of antimicrobial potential of S. nemorea extracts and suggest its potential as natural antimicrobial agent for food preservation.     

High-pressure liquid chromatography fingerprinting of petroleums and petroleum products

Combined GC/HPLC fingerprinting of petroleums and process streams derived therefrom gives detailed information on their constituents. The silica gel-heptane system affords separation into classes of hydrocarbons which, together with dual u.v. and R.I. modes of detection, gives abundant information on the composition of such samples. GC on a medium-efficiency SCOT column is used as a complementary technique only. Interpretations of HPLC chromatograms for samples ranging from gasolines to bitumens are given.     

The analysis of condensation products of 2,6-xylenol and formaldehyde in the presence of cresols

Methylenebisphenols, commonly used as antioxidants for polyolefines, are prepared by condensation of suitably alkylated phenols and formaldehyde in the presence of acid catalyst. Usually by-products are produced from the impurities in starting raw materials. In this work the condensation of 2,6-dimethylphenol with formaldehyde and the influence of cresols was studied. By-products, namely bisphenols and trisphenols were separated by means of gel chromatography and analyzed by reversed phase liquid chromatography, mass spectrometry and nuclear magnetic resonance.     

Diagnose von Korrosionsfällen an einer Saturationskolonne für Synthesegas

Diagnosis of case histories from a synthesis gas saturation column The saturation column, made of steel type 1Cr18Ni9Ti (wall thickness: 8 mm), in which the gas is cooled down to 240°C by a water jet and, simultaneously saturated with water vapour, failed after only 3000 hours' operation; the failure was attributable to a damaged footing tube. An analysis of the damaged parts suggested, that the main cause of the failure was not the design of the equidistant shells, i. e. the welding connection between the tubes and the two shells, which had originally been assumed to be faulty, but in a first line the material selection which was wrong in view of possible corrosion. The tensile stresses resulting from the rigid connection of the footing pipes are but one of the factors contributing to the development of stress corrosion cracking. This opinion concerning the reason of the first failure was confirmed when another failure occurred after another 1000 hours' operation of the column: a thorough inspection revealed some spots where stress corrosion cracking bad developed.     

Experimental investigation and theoretical modeling of dehydriding process in high-pressure metal hydride hydrogen storage systems

This study explores the endothermic dehydriding (desorption) reaction that takes place in a high-pressure metal hydride (HPMH) hydrogen storage system when hydrogen gas is released to the fuel cell. The reaction is sustained by circulating warm fluid through a heat exchanger embedded in the HPMH powder. A systematic approach to modeling the dehydriding process is presented, which is validated against experimental data using two drastically different heat exchangers, one using a modular tube-fin design and the other a simpler coiled-tube design. Experiments were performed inside a 101.6-mm (4-in) diameter pressure vessel to investigate the influences of hydrogen release rate, heat exchanger fluid flow rate and fluid temperature on the dehydriding process for the HPMH Ti_1.1CrMn. It is shown the dehydriding reaction rate can be accelerated by increasing the fluid temperature and/or the rate of pressure drop. HPMH particles located in warmer locations close to heat exchanger surfaces both began and finished dehydriding earlier than particles farther away. 2-D and 3-D models were created in Fluent to assess the dehydriding performances of the modular tube-fin heat exchanger and coiled-tube heat exchanger, respectively. The models are shown to be quite accurate at predicting the spatial and temporal variations of metal hydride temperature during the dehydriding reaction.