Habitat use at fine spatial scale: how does patch clustering criteria explain the use of meadows by red deer ?

Large mammalian herbivores are keystone species in different ecosystems. To mediate the effects of large mammalian herbivores on ecosystems, it is crucial to understand their habitat selection pattern. At finer scales, herbivore patch selection depends strongly on plant community traits and therefore its understanding is constrained by patch definition criteria. Our aim was to assess which criteria for patch definition best explained use of meadows by wild, free-ranging, red deer (Cervus elaphus) in a study area in Northeast Portugal. We used two clustering criteria types based on floristic composition and gross forage classes, respectively. For the floristic criteria, phytosociological approach was used to classify plant communities, and its objectivity evaluated with a mathematical clustering of the floristic relevés. Cover of dominant plant species was tested as a proxy for the phytosociological method. For the gross forage classes, the graminoids/forbs ratio and the percentage cover of legumes were used. For assessing deer relative use of meadows we used faecal accumulation rates. Patches clustered according to floristic classification better explained selection of patches by deer. Plant community classifications based on phytosociology, or proxies of this, used for characterizing meadow patches resulted useful to understand herbivore selection pattern at fine scales and thus potentially suitable to assist wildlife management decisions

Gel-sol transitions of chrome tanned leather waste hydrolysate

The properties of gels of collagenous hydrolysates from enzyme treatment of chrome-tanned leather waste, were monitored with the use of the DSC technique. The temperatures at which gels melt, the energies of the gel-sol transitions (determined by use of the DSC technique) and the gel strength (in degrees Bloom) correspond to those of gels of the qualitative class 9-10, as specified by the National Association of Glue Manufacturers. Due to the lower mean molecular weight of the hydrolysates (when compared with commercially available glues) and the wider molecular weight distribution, hydrolysed gels from enzyme hydrolysates (hydrolysis times less than 3 h) are used at concentrations approximately three times higher than is usual with commercially available glues of the above-mentioned quality. Glues of this qualitative class are often used in industry in concentrations of 50% and higher and thus the higher concentration of hydrolysates from chrome-tanned leather waste will not represent an obstacle when t hey are used in a similar way

Closed loop for chromium in tannery operation

Příspěvek se týká zpracování tuhých a kapalných odpadů z koželužské výroby. Hlavním kritériem byly matematické modely platné pro procesy v koželužství. Navržené modely byly využity při optimalizaci první "mokré" koželužské operace - námoku surových kůží v koželužské výrobě, která se vyznačuje velkou spotřebou užitkové vody a chemikálií. Pro stanovení cílové funkce bylo zvoleno ekonomické hledisko, tj. nákladová funkce.Even though the leather industry is environmentally important as a user of a byproduct of the meat industry, it is still perceived as a consumer of resources and a producer of pollutants. When processing one metric ton of rawhide, 200 kg of a leather-final product is obtained, and only 20% of the raw material weight is converted to leather. The biggest problem, and one that is now under scrutiny, is the disposition of chrome-tanned solid wastes. To keep the chromium from tanned wastes within control limits we have worked out a modified enzymatic dechromation technology and developed it into an industrial scale with a daily capacity of three metric tons of chrome shavings. The chromium-containing sludge, isolated by this technology, contains 10-15% magnesium oxide, and is used (here) as a precipitator for chromium in spent tanning liquor. We treated a spent liquor containing 2294 ppm of chromium with the chromium sludge, obtained from the enzymatic reaction. After the treatment, the content of chromium decreased from the original 2294 ppm to 6 ppm, which means that practically total dechromation of the waste chrome water has occurred. This chrome removal from the spent tanning liquor, using the chrome sludge from digestion of the chrome-tanned solid wastes, effectively provides a closed loop for chromium in tanning operations