The effect of temperature on microbial growth in apple cubes packed in film and preserved by use of orange juice

Red delicious apple cubes were packed in fresh orange juice containing chemical preservatives (citric and ascorbic acid, potassium sorbate) and covered with plastic films of different gas permeabilities (polyethylene and EVA‐SARAN‐EVA) before storage at 4, 10 and 20 °C. The concentration of potassium sorbate in the product was optimized with respect to colour and microbial growth. Yeast and mould growth was modelled by Gompertz and linear equations to derive parameters such as lag phase, maximum microbial population and specific microbial growth or rates of decline. Activation energies for the specific growth rates were estimated from Arrhenius‐type equations and the time required to reach microbial counts of 10^6±0.2 CFU g^?1 was determined in all cases. At 4 °C, these values were longer than 25 days in all systems tested. The use of a low gas permeability film and an adequate potassium sorbate concentration extended storage life at higher temperatures.     

A branch-and-bound algorithm for implementing set covering model expert systems

The conventional rule-based expert system can be formulated as a 0–1, integer program, specifically, as a set covering problem. However, the implementation of an expert system in this way requires that the set covering model be solved for k-best alternate optima or near-optima. We have devised a branch-and-bound algorithm which accomplishes this. The details of the algorithm are explained in the paper. Computational results are provided.     

Coating of intravascular balloon with paclitaxel prevents constrictive remodeling of the dilated porcine femoral artery due to inhibition of intimal and media fibrosis

Here we investigated how a coating of intravascular balloon with paclitaxel (drug-coated balloon; DCB, Freeway?) impacted porcine peripheral artery vascular function and remodeling. Domestic swine (n = 54) underwent percutaneous overstretch balloon dilation of femoral and iliac arteries, controlled by angiography and optical coherence tomography (OCT). Paclitaxel tissue uptake was measured at 1 h and 1, 3, and 9 days post-dilation. At these time-points and at 32 ± 2 days, vascular function of the dilated arteries was assessed using the organ chamber model. Neointimal growth and remodeling indices were determined using OCT and histology at 32 ± 2 days. Intima and media fibrosis were quantified by picrosirius red staining. Post-inflation femoral artery tissue drug levels were 460 ± 214, 136 ± 123, 14 ± 6, and 0.1 ± 0.1 ng/mg at 1 h and 1, 3, and 9 days, respectively. Compared to plain balloon, Freeway? resulted in a significantly smaller neointimal area (P < 0.05), less tunica intima (8.0 ± 5.4 vs 14.2 ± 4.7 %) and media fibrosis (15.6 ± 7.7 vs 24.5 ± 5.4 %), and less femoral artery constrictive remodeling (remodeling index: 1.08 ± 0.08 vs 0.94 ± 0.08). The DCB was associated with significantly increased vasoconstrictor tone and endothelium-dependent vasodilation impairment shortly after post-overstretch injury. Overall, DCB dilation of peripheral arteries resulted in high drug uptake into arterial tissue. Compared with the plain balloon, the DCB was associated with decreased vessel wall fibrosis after balloon overstretch injury, and reduced degrees of constrictive remodeling and neointimal hyperplasia.     

Runaway Carbon Dioxide Conversion Leads to Enhanced Uptake in a Nanohybrid Form of Porous Magnesium Borohydride

Leveraging molecular‐level controls to enhance CO₂ capture in solid‐state materials has received tremendous attention in recent years. Here, a new class of hybrid nanomaterials constructed from intrinsically porous γ‐Mg(BH₄)₂ nanocrystals and reduced graphene oxide (MBHg) is described. These nanomaterials exhibit kinetically controlled, irreversible CO₂ uptake profiles with high uptake capacities (>19.9 mmol g^?1) at low partial pressures and temperatures between 40 and 100 °C. Systematic experiments and first‐principles calculations reveal the mechanism of reaction between CO₂ and MBHg and unveil the role of chemically activated, metastable (BH₃‐HCOO)^? centers that display more thermodynamically favorable reaction and potentially faster reaction kinetics than the parent BH₄^? centers. Overall, it is demonstrated that size reduction to the nanoscale regime and the generation of reactive, metastable intermediates improve the CO₂ uptake properties in metal borohydride nanomaterials.     

The role of BMP-2, low-level laser therapy and low x-ray doses in dental follicle stem cell migration

The knowledge of how cells respond to different treatments in terms of their migration potential could improve bone regeneration and osseointegration of dental implants. The objective of this study was to elucidate the effects of various chemoattractants, bone morphogenetic protein-2 (BMP-2), low-level laser therapy (LLLT), and cone beam computed tomography (CBCT) on the migration of dental follicle stem cells (DFSCs). The chemoattractants used in our study were the serum-free (SF) conditioned media that were harvested from osteoblast cell cultures seeded on the surface of titanium implants—Ti6Al7Nb (TiCtrl), implants infiltrated with hydroxyapatite (TiHA), with silicatitanate (TiSiO₂), and from culture of DFSCs cultivated on TiCtrl implants. We used the scratch migration assay to evaluate the influence of BMP-2, LLLT therapy, and CBCT on the migration potential of DFSCs. The migration scratch assay indicates that the BMP-2 growth factor is able to increase the DFSC migration compared to control culturing medium and regardless of laser or CBCT exposure. The results demonstrate the importance of improving the implant surface with HA, SiO₂, and DFSCs. Stimulated DFSCs will secrete growth factors which will act as chemoattractants for the stem cells of the implant host. Adding growth factors such as BMP-2 can improve the migration process of DFSCs.     

Constrained mixture design applied to the development of cassava starch-chitosan blown films

Films composed of cassava starch, chitosan and glycerol were produced by blown extrusion and employing a design for constrained surfaces and mixtures. The effects of the components of the mixture on the mechanical properties, water vapor permeability (WVP) and opacity of the films were studied. According to the models generated by the design, the concentration of starch had a positive effect in all properties. The plasticizer glycerol and its interactions with other components had a positive effect on increasing the WVP. The presence of a higher relative concentration of chitosan favored the formation of more rigid and opaque and less permeable films. In general, the concentrations of starch, chitosan and glycerol led to changes in the film properties, potentially affecting their performance. The design for constrained surfaces and mixtures proved to be a useful tool for this type of study due to the complexity of the conditions of film formation.     

Effect of chlorine on filamentous microorganisms present in activated sludge as evaluated by respirometry and INT-dehydrogenase activity

Activated sludge technology is more used than any other for biological treatment of wastewater. However, filamentous bulking is a very common problem in activated sludge plants, chlorine being the chemical agent normally used to control it. In this work the effect of chlorine on microorganisms present in activated sludge flocs was assessed by a respirometric technique (oxygen uptake rate, OUR) and by the INT-dehydrogenase activity test (DHA) measured by two techniques: spectrophotometry (DHA(a)) and image analysis (DHA(i)). Both DHA tests were optimized and correlated with the respirometric technique (OUR) using pure cultures of a filamentous microorganism (Sphaerotilus natans) under chlorine inhibition. Using these correlations the tested methods were applied to determine the action of chlorine on respiratory activity in activated sludge. The OUR and the DHA(a) quantifies the action of chlorine on the total respiratory activity (RA) of flocs (filamentous and floc-forming bacteria); in contrast, the DHA(i) test evaluates specific action of chlorine on the RA of filamentous microorganisms. In activated sludge flocs containing filamentous microorganisms, a chlorine dose of 4.75 mgCl(2) (gVSS)(-1) with a contact time of 20 min reduced about 80% of the RA of filamentous bacteria while affecting only 50-60% of the total RA of flocs. Besides, a chlorine dose of 7.9 mgCl(2) (gVSS)(-1) produced the total respiratory inactivation of filamentous microorganisms after 10 min contact, however, with this dose the total RA of activated sludge flocs was reduced only about 45-65%; controlling filamentous bulking without affecting too much floc-forming bacteria. At the tested chlorine concentrations the inhibition of filamentous microorganisms was higher than in the whole activated sludge. Although floc-forming microorganisms were demonstrated to be more susceptible to chlorine than filamentous in pure cultures, results obtained in the present work confirmed that it is the location of the filamentous microorganisms in the flocs and the presence of extracellular polymer substances which largely determines their higher susceptibility to chlorine; consequently this feature plays a critical role in bulking control.     

Fatty acid composition of Celta pig breed as influenced by sex and location of fat in the carcass

BACKGROUND: The influence of sex and location of fat in the carcass on the fatty acid profile of Celta pigs was studied. Twenty pigs (10 castrated males and 10 females) from the Carballina line were used. RESULTS: The fatty acids composition was predominated by monounsaturated fatty acids (MUFA; approximately 48% of total methyl esters), followed by saturated fatty acids (SFA; approximately 40% of total methyl esters) and, finally, polyunsaturated fatty acids (PUFA; approximately 12% of total methyl esters). The sex and location of fat in the carcass showed significant differences in PUFA and SFA content while both factors were not significantly different with respect to MUFA content. Linoleic, linolenic, eicosatrienoic and arachidonic fatty acids showed the largest difference among the three locations (intramuscular, subcutaneous ventral and subcutaneous dorsal) of the fat in the carcass. CONCLUSION: The fatty acid profile that we observed in the fat of the Celta pigs does not differ greatly from those described by other authors in other autochthonous pig breeds. Principal component analysis offered a good separation of the mean samples according to the sex and location of fat of the pigs. Copyright © 2011 Society of Chemical Industry