The extraction of a glucomannan polysaccharide from konjac corms (elephant yam,Amorphophallus rivierii)

Abstract : A process for the micropropagation of Amorphophallus rivierii (elephant yam or konjac) and for the extraction and purification of the glucomannan polysaccharide from fresh konjac plant corms has been developed. This process involves extraction with 2-propanol, which has the additional benefit of extracting carotenoids as a potentially valuable side-product. Starch granules with an unusually high and homogeneous gelatinisation temperature range are normally present in the corms, particularly immature ones, and this greatly reduces the strength of gels formed using the glucomannan. Therefore, the extraction process also involves the selective hydrolysis of the starch, by α- and β-amylases that have been specially selected for an absence of contaminating β-mannanase or β-glucanase activity that would depolymerise the glucomannan and render it nonfunctional. Bacillus lichenformis α-amylase was preferred. Using this process pure glucomannan could be extracted which, when mixed with K -carrageenan, forms a gel almost twice as strong as locust bean gum-K -carrageenan gels of the same concentration.     

Reaction Sequence and Microstructrual Development of CeO2-Doped Reaction-Bonded Mullite

A promising technique for the fabrication of mullite ceramics and mullite-matrix composites with low dimensional changes ("near-net-shape processing") is reaction bonding using Si metal and α-Al₂O₃ as starting materials, because sintering-induced shrinkage is compensated by Si-oxidation-induced volume expansion. A mullite reaction bonding (RBM) route which proceeds at much lower temperatures (lessthan equal to1350°C) than in conventional RBM systems (greaterthan equal to1500°C) is based on Ce doping which provides accelerated Si oxidation and mullite formation due to the formation of transient, low-viscosity Ce-Al-Si-O liquids. The present study shows that the required Ce-Al-Si-O liquids form in a reducing environment with Ce occurring as Ce³⁺. In an oxidizing environment, Ce is present as Ce⁴⁺, giving rise to precipitation of crystalline CeO₂. Ce³⁺ left and right arrow Ce⁴⁺ redox reactions in the temperature range under consideration appear to be controlled by the presence of nonoxidized Si in the samples. According to the present investigation the amount of CeO₂ added to the starting powders must be tailored carefully: Exaggerated CeO₂ content produces large amounts of low-viscosity Ce-Al-Si-O liquids which may have the disadvantage of excessive sealing of the open porosity. This slows the oxygen diffusion velocity into the specimen considerably, with the consequence that nonoxidized Si and a residual Ce-Al-Si-O glass coexist in the ceramics after processing. A solution to this problem is to simultaneously enhance mullite crystal growth through seeding which works against excessive liquid-phase-induced shrinkage of the samples. This in turn enables complete oxidation and recrystallization of all liquid phases.     

Effects of Milling Liquid on the Reaction-Bonded Aluminum Oxide Process

The reaction-bonded aluminum oxide process begins with aluminum, Al₂O₃, and usually ZrO₂ powders that have been attrition-milled in an organic liquid. The attrition-milled powder is then compacted and heat-treated in air to produce polycrystalline, Al₂O₃-based ceramics. Safety considerations have made it desirable for the milling liquid to be changed from acetone to a less-flammable solvent. In this paper, mineral spirits, ethanol, and mineral spirits that contains 2 wt% stearic acid are presented as viable alternatives to acetone. The effects of changing the milling liquid on the reaction process and the properties of the final fired ceramic are investigated.     

The Adhesion‐Enhanced Contact Electrification and Efficiency of Triboelectric Nanogenerators

In the present work, the contact electrification of polymers that differ in adhesion strength is studied. Electrical current is measured along with adhesion in macroscale contacting‐separation experiments. Additionally, local adhesion and roughness are studied with atomic force microscopy to get deeper insight into relations between surface properties and electrification. Measurements reveal that higher surface charge is formed on more adhesive surfaces, thus confirming covalent bond cleavage as a mechanism for contact electrification of polymers. Investigated materials possess enhanced contact electrification making them attractive candidates for the conversion of mechanical energy to electrical in triboelectric nanogenerator devices.     

Lipoxygenase Products in the Urine Correlate with Renal Function and Body Temperature but not with Acute Transplant Rejection

Acute transplant rejection is the leading cause of graft loss in the first months after kidney transplantation. Lipoxygenase products mediate pro- and anti-inflammatory actions and thus we aimed to correlate the histological reports of renal transplant biopsies with urinary lipoxygenase products concentrations to evaluate their role as a diagnostic marker. This study included a total of 34 kidney transplant recipients: 17 with an acute transplant rejection and 17 controls. LTE4, LTB4, 12-HETE and 15-HETE concentrations were measured by enzyme immunoassay. Urinary lipoxygenase product concentrations were not significantly changed during an acute allograft rejection. Nevertheless, LTB4 concentrations correlated significantly with the body temperature (P ≤ 0.05) 3 months after transplantation, and 12- and 15-HETE concentrations correlated significantly with renal function (P ≤ 0.05) 2 weeks after transplantation. In conclusion, our data show a correlation for LTB4 with the body temperature 3 months after transplantation and urinary 12- and 15-HETE concentrations correlate positively with elevated serum creatinine concentrations but do not predict acute allograft rejection.     

Über den Vitamingehalt einiger griechischer Früchte

European Food Research and Technology - Griechische Calmata-Kranzfeigen wurden auf ihren Vitamingehalt geprüft. Sie enthielten in 1 g 2,4 internationale Einheiten Vitamin A, etwa 0,48...