Biomass composition of a Candida pseudotropicalis new strain grown on crude sweet whey

A yeast strain isolated from whey and named Candida LY 496 was grown continuously on crude sweet whey. The obtained biomass had a crude protein content of 47%. The amino acid composition was determined by high performance liquid chromatography (h.p.l.c). All essential amino acids were present and among them lysine was predominant (11.8%). The total nucleic acids of the biomass was 6.4%. Lipids represented 5% and the fatty acids 2% of the dry matter; 75% of the fatty acids were unsaturated, and linoleic acid constituted only 1% of the total fatty acids. Niacin and vitamin B₂ were the most abundant vitamins of the B group. Therefore Candida LY 496 biomass could be incorporated in animal food intakes.     

Investigation of polymer blends of polyamide-6 and poly(methyl methacrylate) synthesized by RAFT polymerization

Morphological and thermal properties of immiscible and incompatible polymer blends of commercial polyamide-6 (PA-6) and poly(methyl methacrylate) (PMMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization have been studied in the presence of a compatibilizer consisting of either a random copolymer of styrene-maleic anhydride (SMA) or a diblock copolymer poly(methyl methacrylate) and polystyrene (PMMA-PS) also synthesized via RAFT polymerization. Blends of PA-6/PMMA were obtained by extrusion mixing. During melt compounding in the extruder, the functional groups of the polymer components were reacted in the presence of a compatibilizer, which changed considerably the morphology of the blend. After compatibilization, particles of PMMA in the PA-6 were smaller and better dispersed. The morphology and thermal properties of the blends were characterized using scanning electron microscopy (SEM) and differential scanning calorimetry (DCS).     

Role of Na2CO3 on an AISI 330 austenitic stainless steels oxidation at 900°C

This study shows the influence of sodium carbonate coatings on the austenitic AISI 330 (Fe–35Ni–19Cr–1.3Si) oxidized during 48 hr at 900°C. The N₂‐5 vol% H₂ gaseous environment was used to simulate industrial heat treatment conditions. Silica scale formation is promoted by low oxygen‐containing gaseous environments and the high alloy silicon content. On this alloy, an amorphous silica scale is formed after the blank material oxidation. It indicates that silicon is free to diffuse in the alloy and forms a silica scale at the internal interface. On Na₂CO₃‐coated specimens, no silica scale is formed. Then, sodium combines with silicon to form amorphous glass particles. A comparison has been performed with results obtained on a AISI 330Cb niobium containing alloy in the same oxidizing conditions. It is then concluded that sodium carbonate coatings could only favor silica formation on niobium containing alloy due to a reaction between sodium and niobium.     

A deposition efficiency model for fiber–filler flocculation by microparticle retention system

A deposition efficiency model was developed in order to predict the effect of the dosage of retention aids (polymer and bentonite) on filler retention and validated with a pilot machine trial. The deposition efficiency is a function of the surface coverage of adsorbed and transferred polymer on solids (fiber and filler) and the surface coverage of microparticles on the polymer-adsorbed layer. The model includes the effect of bimodal particles (i.e., fiber and filler) and the polymer transfer from fiber to filler. In addition, the interaction between bare surfaces was included in the model and different bond strength of each interaction was considered. It was shown that an increase in the deposition efficiency leads to an increase in the filler retention. The dosage of CPAM is more predominant variable affecting deposition efficiency and thus filler retention than that of bentonite.     

Production of Human Milk Fat Substitutes by Interesterification of Tripalmitin with Ethyl Oleate Catalyzed by Candida parapsilosis Lipase/Acyltransferase

In human milk fat, the saturated fatty acids, namely palmitic acid, are located at the sn-2 position of triacylglycerols (TAG) while unsaturated fatty acids (e.g. oleic acid) are esterified at position sn-1,3. Thus, sn-1,3-dioleoyl-2-palmitoylglycerol (OPO) is the target TAG to be used as human milk fat substitutes (HMFS) in infant formulas. In this study, the noncommercial recombinant lipase/acyltransferase from Candida parapsilosis (CpLIP2) was immobilized in Accurel MP1000, and used as a biocatalyst for the interesterification of tripalmitin with ethyl oleate in a solvent-free medium, to obtain structured lipids used as HMFS. Different molar ratios (MR) of ethyl oleate to tripalmitin (2:1–8:1) were used. After 4 h reaction at 60°C, about 30 mol% of oleic acid incorporation was already observed for all tested MR. An apparent equilibrium was reached after 8–24 h, with 32–51 mol% final incorporation, increasing with the MR. The incorporation of oleic acid into TAG was compared with the maximum predicted values when a random or a sn-1,3-regioselective biocatalyst was used. The obtained values are consistent with the maximum incorporation expected for a sn-1,3-regioselective enzyme. In fact, the amount of oleic acid at position sn-2 was approximately 15% for all the MR tested, which is explained by the acyl migration phenomenon. CpLIP2 exhibited higher activity than most commercial immobilized lipases (e.g. faster reaction in solvent-free media, low enzyme load, and low MR needed), and showed a recognized sn-1,3 regioselective behavior.     

Influence of Stabilization Temperature on the Entrapment of Adriamycin in Albumin Microspheres

Adriamycin associated bovine serum albumin (BSA) microspheres have been prepared by the method involving emulsion and suspension technology. Stabilization of the carrier matrix was achieved by heat treatment at 105, 120, 135 and 150°C.

Following zero to four washings, each of these four batches of microspheres have been evaluated for the amount of associated adriamycin using HPLC. At high stabilization temperatures, migration of adriamycin to the microsphere surface is reduced leading to increased drug entrapment. Results demonstrate that the proportion of entrapped to total drug increases with increase in stabilization temperature of the carrier.     

Histological aspects in bone regeneration of an association with porous hydroxyapatite and bone marrow cells

The osteogenic potential of an association of two kinds of hydroxyapatite (HA) porous ceramics with autologous bone marrow cells cultured with or without dexamethasone (10^-8M) addition in the culture medium and non-cultured rabbit marrow stromal stem cells (MSCs) was tested after 4 weeks of implantation in the dorsal muscles of spine in rabbit. A significantly higher number of rabbits with implants containing bone tissue inside pores were obtained with 10⁷ cells ml^-1 cultured treated with Dex. In the HA porous ceramic using naphtalen as porogen agent, the bone recolonization remains only at the periphery of implants and in the second row of pores, while in the HA porous ceramic using polymethacrylate (PMMA) microbeads as porogen agent, the bone recolonization is observed in the depth of implants. In the PMMA HA group, the Kru¨skal–Wallis variance analysis between the rabbits is significantly different with the percentage of number of occupied pores and occupied pores with bone tissue is different (p < 0.05).