Surface pre-coating of talc particles by carboxyl methyl cellulose adsorption : study of adsorption and consequences on surface properties and settling rate

This paper investigates the adsorption of different sized carboxyl methyl cellulose (CMC) onto talc particles (adsorption isotherm, adsorption reversibility), its consequences on the particles properties (electrophoretic mobility and surface wetting) and its effect on their dispersion (settling coefficient). Throughout the paper, the properties of talc particles dispersed in CMC solution are compared to CMC pre-coated talc particles: talc particles dried in a solution of CMC before their redispersion. The adsorption of CMC onto talc was quantified at around 0.4 mg of CMC per m2 of talc and was seen to be irreversible on washing the talc particles with distilled water. When characterising talc surface properties, it was found that CMC adsorption leads to an increase of the negative surface charge and to an increase of the wettability. The settling velocity of CMC pre-coated talc particles in water can be around 50 % lower than that of the initial talc particles. The pre-coating of talc particles by CMC is then assumed to increase their stabilization : particle aggregation is hindered by adsorbed CMC layer inducing electrosteric repulsion between the talc particles. The technique of talc pre-coating with CMC makes the talc dispersion easier and could open interesting perspectives in engineering processes using talc dispersions

Biopreservation of Fresh Strawberries by Carboxymethyl Cellulose Edible Coatings Enriched with a Bacteriocin of Bacillus methylotrophicus BM47

Bacteriocins are a large group of antimicrobial compoundsthat aresynthesized byrepresentatives ofthegenus Bacillusand lactic acid bacteria (LAB). Bacteriocinsare used extensively in thefood industry as biopreservatives. Incorporatedin the composition of edible coatings, bacteriocins canreduce microbial growthand decay incidencein perishable fruits, thusimproving productshelf-life and commercial appearance. The present study aims to investigatethe effect of edible coatings of0.5% carboxymethyl cellulose (CMC) enriched with a purified bacteriocin fromBacillus methylotrophicusBM47 on the shelf-life extension of fresh strawberries. During storage at 4\ub0Cand 75 % relative humidity(RH) for 16 days, measurements of massloss, decay percentage, total soluble solids(TSS), titratable acidity(TA),pH, organic acids, total phenolic and anthocyaninscontents and antioxidant activity were taken.The results demonstrated that the application of 0.5% CMC and 0.5% CMC+bacteriocin (CMC+B) edible coatings led to a significant decrease of massloss in treated strawberriescompared to the uncoated fruit. After the 8-th day of storage, significant reductions in decay percentage along with the absence of fungal growth in CMC+B-coated fruit wereobserved in comparison to the CMC-coated and control strawberries. During the second half of the storage period, CMC and CMC+B treatmentsreduced TSS levels inthe coated fruitcompared to the control, but did not affectincreasedTA and loweredpH valuesthat arenormally associated with post-harvest changes. The CMC and CMC+B coatings wereineffectiveagainst thedecrease inascorbic acid, total phenolics and anthocyanins contentduringcold storage. The application of CMC and CMC+B coatingsexhibited a significant inhibitory effect on decreasing antioxidant activity throughout the storage period and maintained the antioxidant levels inboth treatmentsclose to the initial value of 76.8 mmol TE/100 g of fm

Conformal Parameterizations of Slices of Flat Kasner Spacetimes

The Kasner metrics are among the simplest solutions of the vacuum Einstein equations, and we use them here to examine the conformal method of finding solutions of the Einstein constraint equations. After describing the conformal method's construction of constant mean curvature (CMC) slices of Kasner spacetimes, we turn our attention to non-CMC slices of the smaller family of flat Kasner spacetimes. In this restricted setting we obtain a full description of the construction of certain $U^{n-1}$ symmetric slices, even in the far-from-CMC regime. Among the conformal data sets generating these slices we find that most data sets construct a single flat Kasner spacetime, but that there are also far-from-CMC data sets that construct one-parameter families of slices. Although these non-CMC families are analogues of well-known CMC one-parameter families, they differ in important ways. Most significantly, unlike the CMC case, the condition signaling the appearance of these non-CMC families is not naturally detected from the conformal data set itself. In light of this difficulty, we propose modifications of the conformal method that involve a conformally transforming mean curvature.Comment: 34 pages, 5 figure

Moduli Spaces of Embedded Constant Mean Curvature Surfaces with Few Ends and Special Symmetry

We give necessary conditions on complete embedded \cmc surfaces with three or four ends subject to reflection symmetries. The respective submoduli spaces are two-dimensional varieties in the moduli spaces of general \cmc surfaces. We characterize fundamental domains of our \cmc surfaces by associated great circle polygons in the three-sphere.Comment: latex2e, AMS-latex, 24 page